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1

Design, fabrication and performance analysis of a planetary roll mill for fine grinding  

Directory of Open Access Journals (Sweden)

Full Text Available Reducing milling cost in mineral processing is a problem that has defiled all serious attempts while milling still takes up to 60% of comminution cost. The planetary roll mill is a new innovation for faster and finer grinding. It is designed and fabricated with grinding rolls rotating in a number of arms inside a grinding sphere. A test run of the complete machine with crushed granite and sandstone shows that the machine grinds to fine consistency within a short period of time. A comparison of the products of the machine with that of a standard Denver Laboratory Ball Mill shows that the machine is about 30% more efficient than the ball mill in terms of duration of grinding to a particular size consistency. One advantage of the planetary roll mill is that is can be used as a ball mill if the need arises. It is therefore recommended that this mill be developed for both research and industrial uses.

Ajaka E. O.

2011-04-01

2

Rheology of coal-water slurries prepared by the HP roll mill grinding of coal. Quarterly technical progress report No. 10, December 1, 1994--February 28, 1995  

Energy Technology Data Exchange (ETDEWEB)

The research during this quarter was, directed towards: (1) systematic study of preparation of coal fines by high-pressure roll mill grinding and by high-pressure roll mill/ball mill hybrid grinding, (2) investigation of the rheological behavior of slurries prepared with fines produced by these techniques, and (3) study of the effect of coal cleaning on both short term and long term slurry rheology. Results are discussed.

Fuerstenau, D.W.

1995-03-01

3

Stress and accidental defect detection on rolling mill rolls  

International Nuclear Information System (INIS)

During the rolling mill process, rolls are submitted to high pressures that can lead to local decohesion or metallurgical changes. Both these cracks or softened areas must be detected as soon as they appear because of the risk of spalling, marks on the product, and mill wreck. These defects can be detected using the eddy current method, and particularly sensors specially developed for micro-defects detection. These sensors must be adapted to the environment of a roll grinding machine on which they must be installed. Users' schedule of conditions also require them to be attached to a wide range of eddy current generator and automatic computerized interpretation. Mill requirements for new high tech roll grades and quality lead to continuous development and improvement of the tools that will provide immediate 'go - no go' information. This paper is an update of these developments. (author)

4

Continuous grinding mill simulation using Austin's model  

Directory of Open Access Journals (Sweden)

Full Text Available Comminution is a frequently-required step in mineral processing and is responsible for almost 90% of all energy consumption in a mineral processing plant. Tumbling mill design has been studied since the middle of the XIX century. There are many comminution models in the literature, with preponderance, however, of Austin’s model (2002 for mineral impact breakage. In this paper, Austin’s model was applied to tubular tumbling mills. Once Austin's model was proposed for batch processing of narrowly-distributed fraction sizes, an artifice has allowed it to be used in continuous grinding mill processes with widely-distributed fraction sizes. Interesting results were obtained with errors less than 0.005 for mills with sharp residence time distributions.

Andr\\u00E9 Carlos Silva

2012-01-01

5

Evaluation of Recycle Grinding Performance in Flour Milling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A typical flour milling process is a very linear operation that is almost entirely void of recycled streams where separate fractions from each operation go ahead as new streams to the next operation. In some cases, there are opportunities for combining some streams, for recycling particles that have been insufficiently broken to go back to the same roller mill. This study introduces this recycle concept in flour milling process at second break system. The recycle grinding assessment was made ...

Siti Mazlina Mustapa Kamal; Colin Webb

2007-01-01

6

Development of an energy-saving grinding process applying the high-pressure grinding roll. Final report. Entwicklung eines energiesparenden Mahlverfahrens unter Verwendung der Gutbett-Walzenmuehle nach Prof. Schoenert. Abschlussbericht  

Energy Technology Data Exchange (ETDEWEB)

The intention of the project was to develop an energy-saving grinding process applying the high-pressure grinding roll suggested by Schoenert (D.P. Nr. 2708053) for industrial use, preferably for grinding Portland cement clinker and other brittle bulk materials. As an essential part of the project an industrial pilot plant was to be erected in a German cement factory, consisting of a high-pressure grinding roll as well as of a tube mill, a separator and all required peripheral equipment. With this plant economically interesting power savings and throughput increases were proven for several mode of operation, considering also the improvement of existing conventional plants. Especially the closed-circuit operation of the grinding roll permits power savings of more than 30%. (orig.) With 18 refs., 16 tabs., 16 figs.

Knobloch, O.

1988-07-01

7

Control for Cold Rolling Mills  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This report contains the details in a final research thesis work done rolling mill technology. The work is carried out at Heat Transfer located at Finspång. The main objective of this work is to evaluate thickness and flatness data from the profile to give an optimal start value for the pressure and force applied on the machine and the speed as well, so that the profiles produced, have the right thickness and best possible flatness. Thickness, start value for power, the degree of bending the...

Morad, Antoni; Travancic, Faruk

2005-01-01

8

High-pressure roll mill comminution of heterogeneous multicomponent feeds  

Energy Technology Data Exchange (ETDEWEB)

Highly complex comminution phenomena can occur in the grinding of multi-component feeds such as ores, coal or mill feeds. High-pressure roll mill comminution of heterogeneous multicomponent feeds was simulated with artificial limestone-quartzite mixtures using a piston-die press. The influence of heterogeneous interactions between components of the mixture on grinding path, energy utilization and energy split have been examined. Primary fractures are governed by differential fracture strength and attrition resistance of the components at heterogeneous contacts; subsequent secondary and tertiary fracture events are governed by coarse-fine interactions in the particle-bed. The weaker component is preferentially ground out of the feed size fraction and concentrates in the fines. Energy split among the components in the mixture is a function of their relative fracture strengths. It doubles for limestone and decreases by a factor of 5 for quartzite over the entire range of the mixing ratio.

Gutsche, O.

1995-12-31

9

Research on roll wear of 2050mm hot strip finishing train (CVC Mill) of Baosteel  

International Nuclear Information System (INIS)

In this paper, the general characteristics and affecting factors of work and backup rolls wear of finishing train were analyzed. Taking the CVC finishing mills of 2050mm hot strip mill of Baosteel as an example, the roll wear magnitude and contour were calculated in theory, and measured by the present grinding machine in experiment. The calculated results agree well with the measured data in distribution, and also in general characteristics. Based on the calculated and measured results, an on-line prediction model by which the roll wear distribution characteristics of a CVC mill can be revealed more accurately was proposed. (author)

10

Evaluation of Recycle Grinding Performance in Flour Milling  

Directory of Open Access Journals (Sweden)

Full Text Available A typical flour milling process is a very linear operation that is almost entirely void of recycled streams where separate fractions from each operation go ahead as new streams to the next operation. In some cases, there are opportunities for combining some streams, for recycling particles that have been insufficiently broken to go back to the same roller mill. This study introduces this recycle concept in flour milling process at second break system. The recycle grinding assessment was made using a Satake STR-100 test roller mill. The recycle process was started after the second break system and the number of recycle grinding was up to 7 regrinds. The particle size distribution and ash analysis were produced to describe the behaviour of the recycle grinding performance. The material release was sifted on a range of sieves and the ash content was analysed using a laboratory furnace. The performance for each recycle stage was investigated. It was determined that it is possible for some coarse particles that contain only bran to keep being recycled in the recycle circuit. A purging operation was recommended to be included in the recycle system, to separate the unwanted particles.

Siti Mazlina Mustapa Kamal

2007-01-01

11

Research on work roll thermal crown in cold rolling mill  

Science.gov (United States)

The factors which have influence on the work roll thermal crown in cold strip rolling are discussed. The heat transferring in three directions (radial axis and circumference) were considered for calculating the work roll thermal deformation. Therefore, it is a three dimensions unstable system for the work roll temperature calculation. The plastic deformation work and friction heat are calculated by the divided element and digital integration method. The simplified calculation model is built for the heat transferring along work roll. There are four zones for work roll heat transferring: roll gap zone air cooling zone emulsion zone rolls contact zone. The heat transferring between the zones is decided by the temperature difference. The inter temperature field and thermal deformation of work roll can be calculated by two-dimension finite difference method. The work roll temperature and thermal crown of actual application cold rolling mill are analyzed by the model. By the comparison between calculated values and measured values, the work roll thermal calculation model can meet the accuracy requirement of on-line control.

Song, Lei; Shen, Mingang; Chen, Xuebo; Wang, Junsheng

2013-05-01

12

Fine grinding of brittle minerals and materials by jet mill  

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Full Text Available Various variables affecting grinding, such as air pressure, minerals or materials hardness, feed size were investigated.The limitations of grinding of gypsum, barite, ilmenite, quartz and ferrosilicon were also elucidated by means of particlefineness size distribution and morphology of ground products. It was found that:1 The density of particles, which are in the grinding zone affects the product fineness, i.e. higher feed rate resultsin a larger product size. The appropriate feed rate is suggested to be 0.2~0.5 g/s. Moreover, the density and hardness ofminerals or materials tend to have an effect on the product fineness. Heavy minerals, such as barite or ilmenite, exhibit afiner product size than lighter minerals, like quartz. However, for quartz, the higher hardness also results in a larger d50.2 Air pressure is the most vital variable which affects the grinding by a jet mill. The d50 seems to relate to theapplied air pressure as a power law equation expressed as following:d50 = aP b ; as P 0The a-value and b-value have been found to correlate to the feed size. The higher the air pressure applied the finerthe product size attained. Moreover, air pressure has a greater effect on hard minerals than on softer ones.3 Feed size seems to have a small effect on ground the product fineness of soft materials, such as gypsum andbarite, but a significant effect on that of hard materials, such as ferrosilicon and quartz, in particularly by milling at low airpressures of 2~3 kg/cm2.4 For the breakage behavior and morphology of ground materials, it was also found that the minerals having cleavages,such as gypsum and barite, tend to be broken along their cleavage planes. Thus, the particle size distribution of theseproducts becomes narrower. While quartz, ilmenite, and ferrosilicon have shattering and chipping breakage mechanisms,grinding results in angular shapes of the ground products and a wider size distribution. Blocks or platelets and agglomerationsmay occur during grinding of soft minerals, like gypsum, especially at lower and higher air pressures, respectively.

Lek Sikong

2008-05-01

13

Heavy metals adsorption on rolling mill scale  

International Nuclear Information System (INIS)

A great quantity of industries are responsible for contaminating the environment with the heavy metals which are containing in their wastewaters. The recovery of these metals is both from an environmental and economical points of view of the upmost interest. A study is made of the use of mill scale-originating in the hot rolling of steel-as an adsorbent for the removal of heavy metals from liquid effluents. The adsorption of Zn''2+, Cd''2+ y Pb''2+ on the rolling mill scale was investigated by determination of adsorption isotherms. The effect of time, equilibrium temperature and concentration of metal solution on mill scale adsorption efficiency was evaluated. The adsorption process was analysed using the theories of Langmuir and Freundlich. Desorption process of metals from loaded mill scales was also studied using several doser bent at different experimental conditions. It has been proved that the mill scale is an effective adsorbent for the cations studies in aqueous solutions within the range of the working concentrations. (Author) 32 refs

14

Fine grinding of brittle minerals and materials by jet mill  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Various variables affecting grinding, such as air pressure, minerals or materials hardness, feed size were investigated.The limitations of grinding of gypsum, barite, ilmenite, quartz and ferrosilicon were also elucidated by means of particlefineness size distribution and morphology of ground products. It was found that:1) The density of particles, which are in the grinding zone affects the product fineness, i.e. higher feed rate resultsin a larger product size. The appropriate feed rate is s...

Lek Sikong; Kalayanee Kooptanond; Noparit Morasut; Thammasak Pongprasert

2008-01-01

15

Radiotracer Investigation of Clinker Grinding Mills for Cement Production at Ghacem  

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Full Text Available Radiotracer Residence Time Distribution (RTD method was used to investigate the process of clinker grinding in Ghana Cement Plant (GHACEM at Tema with the objective of determining hold-up and grinding efficiencies of two ball mills operating in close circuit regime. The experiment was conducted using 40Ci Au-198 radiotracer in liquid state and highly sensitive NaI detectors for radiation measurement. The experimental RTD data revealed that the Mean Residence Times (MRT of the material in the milling and separator sections of both mills were the same. It was also observed from the estimated mill efficiencies that mill 4 operated with optimal performance while the efficiency of mill 3 was far below the expected value.

Ishmael Iddisah Mumuni

2011-01-01

16

Analysis of roll stack deflection in a hot strip mill  

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Full Text Available Predictive models are required to provide the bending set point for bending for the flatness control devices at rolling stands of finishing mill of Hot Strip Mill (HSM. A simple model for roll stack deflection at the finishing mill has been illustrated where a modified Misaka’s equation has been used to obtain mean flow-stress. Investigation has been performed to understand the effect of width of roll on roll stack deflection. The bending on the deflection has been found to have a positive effect to reduce the amount of the stack deflection. The results from the sensitivity analysis of the roll width on roll deflection are also described.

Sudipta Sikdar

2007-09-01

17

Analysis of roll stack deflection in a hot strip mill  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Predictive models are required to provide the bending set point for bending for the flatness control devices at rolling stands of finishing mill of Hot Strip Mill (HSM). A simple model for roll stack deflection at the finishing mill has been illustrated where a modified Misaka’s equation has been us [...] ed to obtain mean flow-stress. Investigation has been performed to understand the effect of width of roll on roll stack deflection. The bending on the deflection has been found to have a positive effect to reduce the amount of the stack deflection. The results from the sensitivity analysis of the roll width on roll deflection are also described.

Sudipta, Sikdar; Shylu, John; Ashwin, Pandit; Raju, Dasu.

18

Analysis of roll stack deflection in a hot strip mill  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Predictive models are required to provide the bending set point for bending for the flatness control devices at rolling stands of finishing mill of Hot Strip Mill (HSM). A simple model for roll stack deflection at the finishing mill has been illustrated where a modified Misaka’s equation has been us [...] ed to obtain mean flow-stress. Investigation has been performed to understand the effect of width of roll on roll stack deflection. The bending on the deflection has been found to have a positive effect to reduce the amount of the stack deflection. The results from the sensitivity analysis of the roll width on roll deflection are also described.

Sudipta, Sikdar; Shylu, John; Ashwin, Pandit; Raju, Dasu.

2007-09-01

19

Structural causes of defects in a cast iron mill roll  

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Full Text Available This paper describes an analysis of a defective microstructure of a mill roll. For this purpose, a piece of a broken roll was collected. That roll was made of mottled cast iron. Its microstructure consisted of modular graphite, transformed ledeburite and a matrix composed of bainite and martensite. Metallographic investigations were performed nearby the fracture in the roll. Observations were conducted on polished sections, first not etched, and then etched, which allowed us to trace carefully the propagation of the fracture. There was found a strict correlation between the microstructure of the roll and the progress occurring in the crack. It was ascertained that the basic reason for the damage to the roll was banded precipitations of ledeburitic cementite. In addition, cementite formed a continuous network. Another microstructure defects of that roll are also precipitations of secondary carbides on the boundaries of former grain of austenite as well as the occurrence of upper bainite in its matrix. The results obtained hereunder allow broadening the data base relative to the genesis of damages to mill rolls, which in future will permit one to design a proper microstructure of cast iron mill rolls. Proper microstructure of cast iron mill roll should be shaped at the stage of designing the chemical composition, conditions of crystallization or heat treatment if any.

J. Krawczyk

2008-07-01

20

Technological design for rolling uranium rod by Y-type rolling mill with three rollers  

International Nuclear Information System (INIS)

The fundamental characteristics of Y-type rolling mill with three rollers and the methods for designing and calculating the grooves are described. The feasibility of producing metallic uranium rod is substantiated by the experiment in continuous rolling. The advantage of this process in rolling metallic uranium rod is analysed

 
 
 
 
21

[Occupational skin diseases in rolling-mill workers in aluminum mills].  

Science.gov (United States)

Some data on frequency and nature of occupational dermatological diseases and stigmata, as well as the results of epicutaneous allergy tests done with occupational allergens with 234 rollers in the rolling mills of the aluminum mill in Razine, near Sibenik are presented. We have recorded occupational dermatose in 44 rollers (18.8%). In the hot rolling mill, sixty rollers have undergone the test and there was 16 recorded cases of occupational dermatose (26.6%). In the cold rolling mill, 174 rollers have undergone the test, and the occupational dematose was recorded in 28 rollers (16.1%). Positive epicutaneous allergic reaction on occupational allergens was found in 5 (2.1%) rollers. Occupational stigmata are somewhat more frequent in the hot rolling mill and their ratio is from 48-100%, whereas in the cold rolling mill they are somewhat less frequent ranging between 40.3 and 97.0% of rollers. PMID:2528044

Bali?, J; Klarica, J

1989-01-01

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Investigation of unbalanced mass of a work roll in a cold rolling mill  

Energy Technology Data Exchange (ETDEWEB)

An abrasion due to continuous friction between a work roll and strip causes the mass of the work roll to be unbalanced in the rolling process. We developed a mathematical model for the rolling mill considering the unbalanced mass and verified the model experimentally. The work roll was approximated as a rigid rotor with eccentricity, and the effect of the unbalanced mass on chatter vibration was investigated. The joint forces computed by quasistatic analysis were applied to the work roll in the rolling mill. Transient responses were obtained, and frequency analysis was performed by solving equations of motion using a direct integration method. Horizontal vibrations were more strongly affected by eccentricity than vertical vibrations. In the horizontal direction, a small eccentricity of 1% of the work roll radius considerably increased the amplitude of the chatter frequency.

Kim, Youngdeuk; Park, Hyunchul [Pohang Univ. of Science and Technology Pohang (Korea, Republic of); Kim, Chang Wan [Konkuk Univ., Seoul (Korea, Republic of)

2012-04-15

23

Investigation of unbalanced mass of a work roll in a cold rolling mill  

International Nuclear Information System (INIS)

An abrasion due to continuous friction between a work roll and strip causes the mass of the work roll to be unbalanced in the rolling process. We developed a mathematical model for the rolling mill considering the unbalanced mass and verified the model experimentally. The work roll was approximated as a rigid rotor with eccentricity, and the effect of the unbalanced mass on chatter vibration was investigated. The joint forces computed by quasistatic analysis were applied to the work roll in the rolling mill. Transient responses were obtained, and frequency analysis was performed by solving equations of motion using a direct integration method. Horizontal vibrations were more strongly affected by eccentricity than vertical vibrations. In the horizontal direction, a small eccentricity of 1% of the work roll radius considerably increased the amplitude of the chatter frequency

24

Development of a rational roll pass design for a rolling mill using performance criteria  

Science.gov (United States)

A new technique is developed to analyze the roll pass design of a section rolling mill. Metal forming nonuniformity and efficiency coefficients, which determine the degree of working of a metal microstructure in rolling of section bars, are used as performance criteria. The system of roll passes intended for the production of a round bar 28 mm in diameter is used as an example to analyze possible deformation schemes and the advantages and disadvantages of each scheme.

Vinogradov, A. I.; Timofeeva, M. A.; Korol', S. O.; Traino, A. I.

2013-01-01

25

Corrosion of Cast Iron Mill Plates in Wet Grinding  

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Full Text Available Corrosion studies were carried out on two different maize grinding plates. Maize was soaked in water for three days and the water decanted and used as electrolyte. Mass loss and pH measurements were carried out every 3 days for 15-day period. Results show that, for each plate, mass loss and pH increased with exposure time. Corrosion rates determined from mass loss data was found to be strongly dependent on pH. The observed behaviour may be explained in terms of the chemical composition and/or microstructures of the plates. Results are briefly discussed in terms of the contribution of corrosion to wear.

Anthony ANDREWS

2010-12-01

26

ALSTOM Schusselmuhle fur die feinvermahlung von anhydrit ALSTOM bowl mill for anhydrite fine grinding  

CERN Document Server

After the ALSTOM bowl mill had proved a success during numerous laboratory tests using different industrial minerals, for the first time a mill, type SM 20/12 was commissioned for ATLAS s.c. at Lodz /Poland for anhydrite grinding. Based on corresponding laboratory tests with anhydrite, it was possible to adapt the equipment to the requirements of the material with modified properties. Due to the project preparation together with the customer, the mill could be installed and commissioned according to schedule by a joint team of engineers for erection and commissioning.

Angleys, M

2003-01-01

27

Rolling of molybdenum and niobium tubes on cold-rolling mill with high stiff stand  

International Nuclear Information System (INIS)

To develop the technique of tube production the process of rolling is studied and comparative evaluation of the structure formed is carried out. It is shown that billets of rods deformed by screw rolling have the improved plastic properties and are deformed on cold-rolling mill (CRM) with a high degree of reduction without defect formation. High stiff stand of the CRM permits to produce high-quality molybdenum tubes

28

Performance characteristics of mill rolls from graphite chromium cast iron  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The main requirements for the development of a new grade for the later finishing section of the mill are : good oxidation and thermal behaviour, high wear resistance, good resistance to rolling incidents. The approach of Marichal Ketin to improve the rolling performances in the last finishing stands is presented. The Hi-Cr cast iron possesses excellent wear resistance due to the presence of hard chromium carbides, but its thermal conductivity and sticking properties are fairly low. A graphite...

Lecomte-beckers, Jacqueline; Terziev, L.; Breyer, J. P.

2000-01-01

29

Aplicação de prensas de rolos em minério de ferro High pressure grinding rolls for iron ore  

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Full Text Available O Projeto Minas-Rio, de propriedade da Anglo Ferrous Brazil, prevê a utilização de prensa de rolos para cominuição do undersize do peneiramento (-25,4 mm. Esta é uma aplicação que se torna cada dia mais comum, porém relativamente nova em minério de ferro. Foram realizados estudos no Centro de Pesquisa da Krupp/Polysius na Alemanha, com o objetivo de validar a aplicação de prensa de rolos para minério de ferro, de determinar os principais parâmetros usados no dimensionamento e de avaliar o impacto do aumento da umidade da alimentação na capacidade específica e na distribuição granulométrica do produto. Os excelentes resultados obtidos, nos ensaios em escala-piloto, somados aos ganhos financeiros da aquisição e operação, à maior estabilidade do processo diante variações de w i (work index e à distribuição granulométrica da alimentação, contribuíram para aprovar, de forma irrestrita, a aplicação de prensa de rolos para cominuição de minério de ferro no Projeto Minas-Rio.The Minas-Rio Project that is being implemented by Anglo Ferrous Brazil, foresees the use of HPGR (High Pressure Grinding Rolls to grind the undersize from screening at (-25.4 mm. This application is recent for iron ore comminuting. The study described herein, took place at the Krupp/Polysius Research Center, in Germany, aiming to validate the HPGR application for iron ore, as well as to determine the main parameters used in equipment sizing. The study also aimed to assesses the impact of moisture variation on ore feed in respect to specific grinding capacity and product size distribution. The great results obtained from the sample tests that demonstrated more process stability for the work index (w i and granulometric feed distribution variations, together with the possible financial gains from the HPGR implementation, contributed to the unrestricted approval of the HPGR application for iron ore comminuting in the Minas-Rio Project.

Farley Santos Ribeiro

2010-06-01

30

Aplicação de prensas de rolos em minério de ferro / High pressure grinding rolls for iron ore  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O Projeto Minas-Rio, de propriedade da Anglo Ferrous Brazil, prevê a utilização de prensa de rolos para cominuição do undersize do peneiramento (-25,4 mm). Esta é uma aplicação que se torna cada dia mais comum, porém relativamente nova em minério de ferro. Foram realizados estudos no Centro de Pesqu [...] isa da Krupp/Polysius na Alemanha, com o objetivo de validar a aplicação de prensa de rolos para minério de ferro, de determinar os principais parâmetros usados no dimensionamento e de avaliar o impacto do aumento da umidade da alimentação na capacidade específica e na distribuição granulométrica do produto. Os excelentes resultados obtidos, nos ensaios em escala-piloto, somados aos ganhos financeiros da aquisição e operação, à maior estabilidade do processo diante variações de w i (work index) e à distribuição granulométrica da alimentação, contribuíram para aprovar, de forma irrestrita, a aplicação de prensa de rolos para cominuição de minério de ferro no Projeto Minas-Rio. Abstract in english The Minas-Rio Project that is being implemented by Anglo Ferrous Brazil, foresees the use of HPGR (High Pressure Grinding Rolls) to grind the undersize from screening at (-25.4 mm). This application is recent for iron ore comminuting. The study described herein, took place at the Krupp/Polysius Rese [...] arch Center, in Germany, aiming to validate the HPGR application for iron ore, as well as to determine the main parameters used in equipment sizing. The study also aimed to assesses the impact of moisture variation on ore feed in respect to specific grinding capacity and product size distribution. The great results obtained from the sample tests that demonstrated more process stability for the work index (w i) and granulometric feed distribution variations, together with the possible financial gains from the HPGR implementation, contributed to the unrestricted approval of the HPGR application for iron ore comminuting in the Minas-Rio Project.

Farley Santos, Ribeiro; José Francisco Cabello, Russo; Thiago, Costa.

2010-06-01

31

Aplicação de prensas de rolos em minério de ferro / High pressure grinding rolls for iron ore  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O Projeto Minas-Rio, de propriedade da Anglo Ferrous Brazil, prevê a utilização de prensa de rolos para cominuição do undersize do peneiramento (-25,4 mm). Esta é uma aplicação que se torna cada dia mais comum, porém relativamente nova em minério de ferro. Foram realizados estudos no Centro de Pesqu [...] isa da Krupp/Polysius na Alemanha, com o objetivo de validar a aplicação de prensa de rolos para minério de ferro, de determinar os principais parâmetros usados no dimensionamento e de avaliar o impacto do aumento da umidade da alimentação na capacidade específica e na distribuição granulométrica do produto. Os excelentes resultados obtidos, nos ensaios em escala-piloto, somados aos ganhos financeiros da aquisição e operação, à maior estabilidade do processo diante variações de w i (work index) e à distribuição granulométrica da alimentação, contribuíram para aprovar, de forma irrestrita, a aplicação de prensa de rolos para cominuição de minério de ferro no Projeto Minas-Rio. Abstract in english The Minas-Rio Project that is being implemented by Anglo Ferrous Brazil, foresees the use of HPGR (High Pressure Grinding Rolls) to grind the undersize from screening at (-25.4 mm). This application is recent for iron ore comminuting. The study described herein, took place at the Krupp/Polysius Rese [...] arch Center, in Germany, aiming to validate the HPGR application for iron ore, as well as to determine the main parameters used in equipment sizing. The study also aimed to assesses the impact of moisture variation on ore feed in respect to specific grinding capacity and product size distribution. The great results obtained from the sample tests that demonstrated more process stability for the work index (w i) and granulometric feed distribution variations, together with the possible financial gains from the HPGR implementation, contributed to the unrestricted approval of the HPGR application for iron ore comminuting in the Minas-Rio Project.

Farley Santos, Ribeiro; José Francisco Cabello, Russo; Thiago, Costa.

32

Grinding energy and physical properties of chopped and hammer-milled barley, wheat, oat, and canola straws  

Energy Technology Data Exchange (ETDEWEB)

In the present study, specific energy for grinding and physical properties of wheat, canola, oat and barley straw grinds were investigated. The initial moisture content of the straw was about 0.13–0.15 (fraction total mass basis). Particle size reduction experiments were conducted in two stages: (1) a chopper without a screen, and (2) a hammer mill using three screen sizes (19.05, 25.4, and 31.75 mm). The lowest grinding energy (1.96 and 2.91 kWh t-1) was recorded for canola straw using a chopper and hammer mill with 19.05-mm screen size, whereas the highest (3.15 and 8.05 kWh t-1) was recorded for barley and oat straws. The physical properties (geometric mean particle diameter, bulk, tapped and particle density, and porosity) of the chopped and hammer-milled wheat, barley, canola, and oat straw grinds measured were in the range of 0.98–4.22 mm, 36–80 kg m-3, 49–119 kg m-3, 600–1220 kg m-3, and 0.9–0.96, respectively. The average mean particle diameter was highest for the chopped wheat straw (4.22-mm) and lowest for the canola grind (0.98-mm). The canola grinds produced using the hammer mill (19.05-mm screen size) had the highest bulk and tapped density of about 80 and 119 kg m-3; whereas, the wheat and oat grinds had the lowest of about 58 and 88–90 kg m-3. The results indicate that the bulk and tapped densities are inversely proportional to the particle size of the grinds. The flow properties of the grinds calculated are better for chopped straws compared to hammer milled using smaller screen size (19.05 mm).

J.S. Tumuluru; L.G. Tabil; Y. Song; K.L. Iroba; V. Meda

2014-01-01

33

Digital technology for radiometric thickness gages in rolling mills  

International Nuclear Information System (INIS)

In this paper a nuclear (Am-241, Sr-90) computer-controlled thicknessgerge is described, utilizing the digital technologies additionally for transmission and filtration of signals of the receiver for automatic computation of the calibration curves, automatic standardization over the gauge range and on-line digital diagnosis. This device works without contact and can be used in cold and hot rolling mills. (orig.)

34

Microbiological treatment of recirculating wastewater from cleaning rolls in a rolling mill.  

Science.gov (United States)

In industry, the use of biological methods for cleaning wastewater is increasing. The number of airborne Gram-negative bacteria was high in relation to the use of high pressure water in a rolling mill using recirculated water for cleaning rolls. Analyzing the total amount and species of microorganisms indicates whether they are emitted from a polluted source or consist of the normal airborne flora. PMID:8116637

Lundholm, M; Grönqvist, B

1994-01-01

35

A contact-type tensionmeter for hot rolling mills  

Science.gov (United States)

To improve the hot rolled strip quality and operational stability, a novel tensionmeter based on lever principle is developed which inspects latent waves and provides real references for flatness control in hot rolling process. The contact-type tensionmeter including two segmented rolls can get the transverse tension distribution along the strip width. Tension profile is deduced by different ratio of four force values from the embedded force sensors in tensionmeter system. The compact mechanical structure ensures the tensionmeter's robust stability in hot rolling process, standard hardware and software for data acquisition make the system easy to operate and maintain. The trails have proven tensionmeter successful in improving both strip flatness and mill performance.

Zhao, Xiaoyan; Zhang, Zhaohui; Sun, Yikang; Wang, Jun; Que, Cheng

2008-12-01

36

Development and investigation of a two-line tube rolling on the KhPT-55 cold tube rolling mill  

International Nuclear Information System (INIS)

A change for the two-thread rolling accomplished at the Pervoural'skij new-tube work in 1969 is an effective way of increasing the productivity of the functioning mills of cold tube rolling. A brief description and technological characteristics of the modified KHPT-55 rolling-mill are given. The mill started to roll two steel tubes simultaneously for the first time. The results of an experimental study of the two-thread and one-thread rolling-mills including the determination of the power-strength parameters are presented. The structural shortcomings of the initial model eliminated in the process of operation are described. Despite the decrease in the feed and the number of double passes per minute and some increase in idling, the rolling-mill productivity increased 1.5 times

37

Optimization of a Heavy Continuous Rolling Mill System Via Simulation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The objective of this study was to develop an integrated simulation model, which generates a set of optimizing alternatives for a heavy continuous rolling mill system in a full-scale steelmaking factory. The simulation approach enabled us to evaluate the performance of the existing system and pinpointed existing bottlenecks in workstations and production flow. Consequently, it generated a set of optimum production alternatives. Data related to process and operation times, repairs, maintenance...

Ali Azadeh; Farid Ghaderi

2006-01-01

38

Grinding efficiency of a newly developed continuous annular-stirred bead mill. Part 1; Shisakushita renzoku anyura gata shisshiki baitai kakuhan miru no funsai seino. 1  

Energy Technology Data Exchange (ETDEWEB)

Commonly, in ink, coating or the fields of chemical, medical, food, electric industries, as a dispersing purpose of grinding the solid particles and making the agglutinating particles into one-time particles, various stirred bead mills are widely used. In this paper, for the purpose of developing a grinding machine of which the grinding of feed through a mill was uniform and its product is fine and has a narrow particle size distribution, a continuous annular-stirred bead mill, which a cylindrical rotor with regularly arranged geometric protuberances on surface was installed in a cylinder with water jacket, was produced for trial and the grinding efficiency of this mill was investigated. Then, the shape of the protuberances on the surface and the grinding effect were investigated. Its results were shown that a rotor with protuberance, the side of which is vertical to the rotational direction of a rotor, has the highest grinding efficiency. 13 refs., 11 figs.

Kamiwano, M.; Kaminoyama, M.; Arai, K. [Yokohama National Univ. (Japan). Faculty of Engineering; Inoue, Y.; Hase, K. [Inoue Mfg. Inc., Kanagawa (Japan)

1993-09-20

39

Optimize cold sector material flow of a steel rolling mill  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The steel production is a highly capital and energy intensive industry that due to recent raw materials’ price increase and lowered demand, it has been squeezed and forced to look more deeply on how to add value to the customer at lower operative costs. The project was carried out on site at the ArcelorMittal’s millin Esch-Belval, Luxembourg which comprises an integrated melt shop, continuous casting plant and the rolling mill with the objectives of proposing optimization rules for the co...

Baudet, Alvaro

2010-01-01

40

Modelling and control of a hot rolling mill  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: English Abstract in english In this paper, a real application of optimal control of a hot rolling mill is presented. It is used the state space model formulation in the minimization of the strip thickness variations. It is presented the simulation results of the control model, which is compared with industrial real data from p [...] rocess controled by traditional techniques. The results of the simulations lead to a less output thickness variations compared with the real industrial data.

F. G., Rossomando; J., Denti Filho.

 
 
 
 
41

PENELITIAN OPTIMASI TEMPERATUR YANG MEMPENGARUHI KEKERASAN PADA PEMBUATAN GRINDING BALL DENGAN CARA HOT ROLLING  

Directory of Open Access Journals (Sweden)

Full Text Available Hardness is one of the mechanical properties needed in a grinding ball. The hardness of grinding ball produced up to now is gained by trial and error to those parameters which are presumed influencing the hardness. Research is done to get parameter influence the hardness of grinding ball and optimum level. Three parameters presumed influencing the hardness are temperature of raw material (Tm, the initial temperature of quenching (Tq, and the final temperature of quenching (Tt. Design of experiment is used to analysis which parameter influence the hardness. A 23 factorial design is chosen, each parameter has two level. According to experiment and data analysis, the influencing parameter are Tq, Tt and interaction between Tq and Tt. The optimum value of Tq and Tt are 905 ± 10°C and 133 ± 3°C, value of Tm is 1110 ± 10°C. Abstract in Bahasa Indonesia : Kekerasan merupakan salah satu sifat yang dibutuhkan oleh grinding ball. Untuk mendapatkan sifat tersebut hingga saat ini masih dilakukan dengan cara trial and error sehingga sangatlah tidak efektif. Maka dari itu dilakukan suatu penelitian untuk mengetahui parameter-parameter yang mempengaruhi kekerasan grinding ball dan level yang optimal. Ada tiga parameter yang diduga mempengaruhi kekerasan grinding ball, yaitu temperatur raw material (Tm, temperatur awal proses quenching (Tq dan temperatur akhir proses quenching (Tt. Untuk menganalisa parameter-parameter yang berpengaruh digunakan desain eksperimen. Desain eksperimen yang digunakan adalah rancangan faktorial 23, masing-masing terdiri atas 2 level. Dari percobaan dan analisa data, tampak bahwa parameter yang berpengaruh adalah Tq, Tt serta interaksi antara Tq dan Tt. Nilai Tq dan Tt yang optimum adalah 905 ± 10°C dan 133 ± 3°C, sedang nilai Tm yang dianjurkan 1110 ± 10°C. Kata kunci: Desain eksperimen, grinding ball, temperatur quenching

Amelia Amelia

2000-01-01

42

Slip Line Field Solution for Second Pass in Lubricated 4-High Reversing Cold Rolling Sheet Mill  

Directory of Open Access Journals (Sweden)

Full Text Available The development of a possible slip line field (slf for theoretical calculations of the deforming pressure (load in a second pass of a lubricated cold rolling sheet mill and validation using values from an aluminium sheet rolling mill was done in this work. This will be relevant in the manufacturing industries providing an easy method for determining necessary applied rolling load. Experimental rolling was carried out to observe the shear lines in the deformation field. Construction of possible slip line field model was developed adhering strictly to assumptions of rigid plastic model. Calculation of the deforming force/load was achieved using Hencky’s equation. Results showed that the load calculations for constructed slip line field using aluminium sheet rolling as an example tallied with values obtained from Tower Aluminium rolling mill. Slip line fields constructed for the second pass described adequately the rolling pressure in the cold rolling process, giving a valid solution of the exact load estimates on comparison with the industrial load values. Roll pressure along the arc of contact rose fairly linearly from the entrance to a maximum at the exit point. This work showed that slf for the first pass in a cold rolling mill cannot be used for subsequent passes; it requires construction of slfs for each pass in the cold rolling process.

Oluleke O. Oluwole

2011-12-01

43

Sequential supervisory control, modelling and simulation of a multipass experimental rolling mill  

International Nuclear Information System (INIS)

This paper presents a Grafcet Model to control a laboratory-scale rolling mill and describes the design of a hybrid modelling and simulation strategy, its implementation in the G2 Real-time Expert System, and its application to the rolling mill. The rolling mill with its process variables and datalogging system is described. Grafcet is briefly overviewed, together with the implementation of the model on the rolling mill. The hybrid model base for the mill is designed from a combination of Object-Orientation, Rule-based Programming, GRAFCET, Equations, and procedures. The strategy, implemented in the real-time expert system, G2, involves the concurrent execution of three simulators: a continuous simulator, a GRAFCET simulator, and a heuristic simulator. (author)

44

Crush Grinding  

International Nuclear Information System (INIS)

Crush Grinding is a special process used at the Kansas City Plant to finish stem sections of reservoir products. In this process, a precise profile of the desired product is formed on a tungsten carbide roll. This roll slowly transfers a mirror image of the profile onto the grinding surface of a wheel. The transfer rate of the profile is between 0.001 and 0.010 inches per minute. Crush grinding is desirable since it provides consistent surface finishes and thin walls at a high production rate. In addition, it generates very sharp fillet radii. However, crush grinding is a complex process since many variables affect the final product. Therefore, the process requires more attention and knowledge beyond basic metal removal practices. While the Kansas City Plant began using these machines in 1995, a formal study regarding crush grinding has not been conducted there. In addition, very little literature is available in the grinding industry regarding this process. As a result, new engineers at the Kansas City Plant must learn the process through trial and error. The purpose of this document is to address this literature deficit while specifically promoting a better understanding of the stem crush grinding process at the Kansas City Plant.

45

A small economical rolling mill for producing foils used as nuclear targets  

International Nuclear Information System (INIS)

A small, economical rolling mill has found extensive use in the Physics Division Target Development Laboratory for producing foils used in atomic and nuclear physics experiments. This apparatus is quite versatile for its size and enables a large fraction of our target foil requirements to be realized in-house. A description of the rolling mill and some examples of targets produced will be given

46

Production of stainless steel tubes at 140 tube-rolling mill  

International Nuclear Information System (INIS)

At the tube-rolling aggregate of the 140 tube-rolling mill the process has been investigated of tube rolling in size of 146x12-16 mm from the 08Kh18N10T steel for cold conversion. Both, the hot-rolled and the cold-rolled tubes have stood the intercrystallite corrosion test and fully conform to the necessary requirements. At the TRA-140 the production of tubes in size of 146x12-16 mm from the stainless steel has been mastered

47

INVESTIGATION OF THE MAINTENANCE ORGANISATION FOR HOT ROLLING MILLS  

Directory of Open Access Journals (Sweden)

Full Text Available

ENGLISH ABSTRACT: Production systems have undergone dramatic changes in recent years. Many companies have implemented new technologies such as flexible manufacturing systems. There is therefore a shift in focus to maintenance and the effective management thereof. Maintenance is a dynamic activity and is comprised of a large number of interacting variables. An effective maintenance organisation is required to control these variables .
This paper discusses the building of a maintenance organisation and the aspects that should be considered during the design. The way in which five companies that operate hot rolling mills apptoached the problem of building an effective maintenance organisation was investigated.

AFRIKAANSE OPSOMMING: y eryaardigingstelsels het drastiese veranderinge ondergaan die afgelope aantal jaar. Verskeie Il1~atskappyemaak nou gebruik van nuwe tegnologiee, soas byvoorbeeld aanpasbare vervaardigingstelsels. Daar is gevolglik 'n verskuiwing in fokus na instandhouding en die effektiewe bestuur daarvan. lnstandhouding is 'n dinamiese aktiwiteit en behels 'n groot aantal ' gekoppelde veranderlikes. 'n Effektiewe instandhoudingsorganisasie word benodig om hierdie v'eranderlikes te beheer.
Hierdie artikel bespreek die daarstelling van die instandhoudingsorganisasie en die parameters V~toorweeg moet word tydens die ontwerp. Die wyse waarop vyf maatskappye wat }V~rIl1walse bedryf die ontwikkeling van 'neffektiewe organisasie vir instandhouding benader hc(is ondersoek .

P.K. Pretorius

2012-01-01

48

Development of alignment-guidance device for grooved roll mill using parallel projection imaging technique  

Science.gov (United States)

The accuracy in the arrangement of grooved rolls for the finishing rolling mill is of large importance for the good roundness of the bar steel product supplied to the precision machinery components such as the bearing of the high speed motor. Combining telecentric optics, silhouette image processing techniques, and statistical data processing allowed the development of the quantitative alignment guidance technique of the grooved rolls. The developed system demonstrated a high measuring accuracy and was seen to have practical use.

Kodama, Toshifumi; Iwata, Teruhisa; Yamagami, Daisaku; Takagi, Keiji

2013-04-01

49

Grinding Wear Behaviour of Stepped Austempered Ductile Iron as Media Material During Comminution of Iron Ore in Ball Mills  

International Nuclear Information System (INIS)

An attempt has been made to evaluate the suitability of austempered ductile iron (ADI) as media material for grinding iron ore in a ball mill. Spheroidal graphite (S.G) iron balls are austenitised at 900 deg. C for 60 minutes and given stepped austempering treatment at 280 deg. C for 30 minutes and 60 minutes followed by 380 deg. C for 60 minutes in each case. These materials are characterised by measuring hardness, analysing X-ray diffraction (X-RD), studying microstructure using optical and scanning electron microscope (SEM). Grinding wear behaviour of these materials was assessed for wear loss in wet condition at different pH value of the mineral slurry and found that the wear rate of grinding media material decreases with increase in pH of the slurry. The wear resistance of ADI balls were compared with forged En31 steel balls and found that the stepped austempered ductile iron is superior to forged En31 steel balls.

50

Study on the improved accuracy of strip profile using numerical formula model in continuous cold rolling with 6-high mill  

International Nuclear Information System (INIS)

The quality requirements for thickness accuracy in cold rolling continue to become more stringent. In cold rolling mill, it is very important that the rolling force calculation considers rolling conditions. The rolled strip thickness was predicted using calculated rolling force. However, the prediction of strip thickness in cold rolling is very difficult; in particular, for 6-high mill with shifted intermediate roll (IMR), the accuracy of thickness is not good. In this study, to improve the accuracy of rolled strip thickness, the roll gap flattening can be given based on Hertz contact theory, with contact between rolls and the smooth cylindrical rolls for the rolling elastic deformation. Also, the distribution of the roll gap flattening may be calculated using the contact force of unit transverse length. The strip profile at the continuous cold rolling is calculated by using the numerical analysis model considering the initial strip profile before cold rolling. Hence, we propose that the numerical model can predict the rolled strip profile more quickly and accurately and be applicable to the field. The results of the proposed numerical model were verified by FE-simulation and cold rolling experiments of 6-high mill with five stands

51

Reliable roll force prediction in cold mill using multiple neural networks.  

Science.gov (United States)

The cold rolling mill process in steel works uses stands of rolls to flatten a strip to a desired thickness. The accurate prediction of roll force is essential for product quality. Currently, a suboptimal mathematical model is used. We trained two multilayer perceptrons, one to directly predict the roll force and the other to compute a corrective coefficient to be multiplied to the prediction made by the mathematical model. Both networks were shown to improve the accuracy by 30-50%. Combining the two networks and the mathematical model results in systems with an improved reliability. PMID:18255691

Cho, S; Cho, Y; Yoon, S

1997-01-01

52

An application of digital filter to roll eccentricity control on strip rolling mill  

International Nuclear Information System (INIS)

Roll eccentricity on strip thickness gauge has been a vital issue among rolling engineers. We present the results of basic consideration of roll eccentricity and its effects on strip thickness gauge. We analyzed some solutions comparatively and show a new application of digital filtering technology. Digital filter that estimates directly the eccentricity waveform along with back up roll rotation has only little effect on thickness gauge. Any type of roll force automatic gauge control works without any inconsistency. The proposed roll eccentricity control is simple and can be installed in any real time programmable logic controllers. (author)

53

Rolling process simulation of a pair-crossed hot strip mill  

Energy Technology Data Exchange (ETDEWEB)

Process simulation can help optimize the operating parameters aiming to improve the quality of rolled products. In this paper, software in Visual Basic language is developed to simulate the hot rolling process of a pair-crossed mill. The strip temperature is calculated by considering air cooling, water cooling, heat generation and conduction.The production parameters including rolling speeds, resistance to deformation, rolling forces, drive torques and powers are evaluated by mathematical models and their parameter identification support tools. The deformation of roll stack is calculated by influential function method. The roll temperature and expansion are calculated by finite differential method, and the roll wear is described by empirical formula. Based on these calculations as well as the effect of heredity is taken into account, the strip crown and flatness then can be obtained. The results show that the simulation software has friendly user interface, high accuracy and practicability. It can be served as a basis for the mill design and optimization of process parameters to acquire high quality of hot rolled strip. (author)

Chen Shaojie; Xu Jianzhong; Liu Xianghua; Wang Guodong [Northeastern Univ., State Key Lab of Rolling and Automation, Shenyang City (China)

2000-07-01

54

In-line material characterization measurements in high speed rod rolling mills  

International Nuclear Information System (INIS)

The ability to provide reliable and timely feedback on the performance of the thermomechanical process in a rolling mill is becoming more important as rolling speeds continue to increase. With rolling speeds now exceeding 120 m/s and production rates exceeding 100 t/h on single strand mills, rapid measurement of the finished product is required to evaluate the process before much unacceptable product is rolled. Conventional means of sample taking, specimen preparation and testing are not only labor-intensive, but also result in relatively slow feedback to the process operators. This paper describes the application of surface volume imaging technology to on-line measurement of pertinent material properties of steel rod. The system examines the microstructural features of the product, such as grain size, crystallographic texture and phase distribution, and correlates those features with mechanical properties such as tensile strength. Furthermore, surface characteristics of the oxide layer can be evaluated and quantified. (author)

55

Extended Kalman Filter Based Neural Networks Controller For Hot Strip Rolling mill  

International Nuclear Information System (INIS)

The present paper deals with the application of an Extended Kalman filter based adaptive Neural-Network control scheme to improve the performance of a hot strip rolling mill. The suggested Neural Network model was implemented using Bayesian Evidence based training algorithm. The control input was estimated iteratively by an on-line extended Kalman filter updating scheme basing on the inversion of the learned neural networks model. The performance of the controller is evaluated using an accurate model estimated from real rolling mill input/output data, and the usefulness of the suggested method is proved

56

Extended Kalman Filter Based Neural Networks Controller For Hot Strip Rolling mill  

Science.gov (United States)

The present paper deals with the application of an Extended Kalman filter based adaptive Neural-Network control scheme to improve the performance of a hot strip rolling mill. The suggested Neural Network model was implemented using Bayesian Evidence based training algorithm. The control input was estimated iteratively by an on-line extended Kalman filter updating scheme basing on the inversion of the learned neural networks model. The performance of the controller is evaluated using an accurate model estimated from real rolling mill input/output data, and the usefulness of the suggested method is proved.

Moussaoui, A. K.; Abbassi, H. A.; Bouazza, S.

2008-06-01

57

Tribological Testing of Anti-Adhesive coatings for Cold Rolling Mill Rolls--Application to TiN-Coated Rolls  

International Nuclear Information System (INIS)

Roll life is a major issue in cold strip rolling. Roll wear may result either in too low roll roughness, bringing friction below the minimum requested for strip entrainment; or it may degrade strip surface quality. On the contrary, adhesive wear and transfer (''roll coating'', ''pick up'') may form a thick metallic deposits on the roll which increases friction excessively and degrades strip surface again [1]. The roll surface, with the help of a materials-adapted lubricant, must therefore possess anti-wear and anti-adhesive properties. Thus, High Speed Steeel (HSS) rolls show superior properties compared with standard Cr-steel rolls due to their high carbide surface coverage. Another way to improve wear and adhesion properties of surfaces is to apply hard metallic (hard-Cr) or ceramic coatings. Chromium is renowned for its excellent anti-wear and anti-adhesive properties and may serve as a reference. Here, as a first step towards alternative, optimised coatings, a PVD TiN coating has been deposited on tool steels, as previous attempts have proved TiN to be rather successful in cold rolling experiments [2,3]. Different tribological tests are reported here, giving insight in both anti-adhesive properties and fatigue life improvement.

58

Methods for increasing the service durability of cold rolling mill rolls  

Science.gov (United States)

Various conditions of heat treatment of low-alloy pearlitic steels, medium-alloy martensitic and pearlitic-martensitic steels, and high-alloy ledeburitic roll steels are studied. Practical recommendations for increasing the quality of roll tools are developed. They consist of the application of cyclic heat treatment, including cyclic subzero treatment. The increase in the service durability of rolls after the implementation of these recommendations under industrial conditions is analyzed.

Yusupov, V. S.; Doronin, I. V.; Antipov, V. I.; Rusakov, A. D.; Alekseev, P. A.; Lukina, Yu. A.

2011-11-01

59

Coupled dynamic modeling of rolls model and metal model for four high mill based on strip crown control  

Science.gov (United States)

The crown is a key quality index of strip and plate, the rolling mill system is a complex nonlinear system, the strip qualities are directly affected by the dynamic characteristics of the rolling mil. At present, the studies about the dynamic modeling of the rolling mill system mainly focus on the dynamic simulation for the strip thickness control system, the dynamic characteristics of the strip along the width direction and that of the rolls along axial direction are not considered. In order to study the dynamic changes of strip crown in the rolling process, the dynamic simulation model based on strip crown control is established. The work roll and backup roll are considered as elastic continuous bodies and the work roll and backup roll are joined by a Winkler elastic layer. The rolls are considered as double freely supported beams. The change rate of roll gap is taken into consideration in the metal deformation, based on the principle of dynamic conservation of material flow, the two dimensional dynamic model of metal is established. The model of metal deformation provides exciting force for the rolls dynamic model, and the rolls dynamic model and metal deformation model couple together. Then, based on the two models, the dynamic model of rolling mill system based on strip crown control is established. The Newmark-? method is used to solve the problem, and the dynamic changes of these parameters are obtained as follows: (1) The bending of work roll and backup roll changes with time; (2) The strip crown changes with time; (3) The distribution of rolling force changes with time. Take some cold tandem rolling mill as subject investigated, simulation results and the comparisons with experimental results show that the dynamic model built is rational and correct. The proposed research provides effective theory for optimization of device and technological parameters and development of new technology, plays an important role to improve the strip control precision and strip shape quality.

Sun, Jianliang; Peng, Yan; Liu, Hongmin

2013-01-01

60

Calculation and experimental technique of determination of rolling procedure for cold-rolling tube mills  

International Nuclear Information System (INIS)

Calculation and experimental technique of determination of tube cold rolling procedure has been developed. Rolling procedure based on the usage of regression equation epsilon=1.24 psi, where psi is the relative reduction of area, delta-permissible reduction during rolling, has been tested on 08Kh18N10T steel. The effect of tube geometry, tool calibration parameters, lubrication conditions etc. on metal deformability in taking into account experimentally. The use of the technique proposed has allowed to shorten the time of mastering of the production of tubes from different steels

 
 
 
 
61

Soft Starting Arrangements Availables for Hot Rolling Mills for Energy Conservation  

Science.gov (United States)

The conventional rolling mills in India are producing a major part of structural steel requirement of the country. The energy conservation in these rolling mills can be achieved mainly by reducing the size of the prime mover i.e. main electric motor. The power consumption per ton can be considerably decreased through proper selection of electric motor since it has been an observation by many surveyors[1] that the selection of electric motor of the rolling mill has been almost five to ten times on the higher side which can be easily verified from the power consumption and motor working data.Flywheel is a mechanical storage device. Largest size of flywheels are frequently recommended for smooth running of rolling mills. The main difficulty encountered in selecting large capacity flywheel or flywheel gear box system is the starting of the mill with smaller capacity electric motor. The starting characteristic of electric motor is not suitable for starting such rolling mill with very high inertia flywheel. In such condition it becomes very essential to introduce the soft starting arrangement for the electric motor so that considerably small size motor can start the flywheel effectively.Soft starters are used for the smooth start-up control of three-phase induction motors. The soft starter is functionally located between the Flywheel and the electric motor. In selecting the correct soft starter to suit the application the peculiarities of the soft start should be considered. In the prevailing conditions we use the motor of high horse power due to the fact that the flywheel requires high torque to be driven initially. For the same reason the efficiency of the flywheel is very low initially. Once the flywheel stores sufficient power which is required at the start up, the flywheel then requires less power than given initially. If we somehow are able to increase the efficiency of the flywheel using a flexible electrical, mechanical, hydraulic or flexible drives with different combinations (Electrical, Mechanical, Hydraulic) then the motor of less horse power can thus be installed to run the flywheel.This paper gives an idea of available type of the soft starting arrangement for a rolling mill so that horse power of motor can be reduced without affecting the working of the mill. Hence optimum selection of the soft starting arrangement is to be done so that initial and billing cost will be less.

Bisen, A. M.; Bapat, P. M.; Gagnuly, S. K.

2012-07-01

62

Design of Rolling State Observers for Application to Control of Thickness and Tension in Rolling Mills  

Directory of Open Access Journals (Sweden)

Full Text Available This study focuses on the necessity of designing state observers to be used in controller synthesis for rolling processes. This is motivated by the fact that using several kinds of sensors for measuring all of process variables is technically and economically avoided. On the other hand, using exact measurement in feedback control systems could considerably improve the quality of products. In other word, there is a trade-off between high quality and the implementation limitations, managed here by developing rolling state observers. The proposed observers estimate the states not measured directly by the installed sensors. This technique is applicable to both hot rolling and cold rolling processes. Simulation results demonstrate the performance of the proposed estimation algorithm.

Hamid R. Koofigar

2011-09-01

63

Regulation of the Heating Furnace in Tube Rolling Mill  

Directory of Open Access Journals (Sweden)

Full Text Available The rolling of tube requires homogeneous heating along the tube. In steel work the difference along tube was sometimes 80 °C. The reasons for bad homogeneousness of heating were analyzed by a simulation model of heating furnace. Then the proposal was made for a new control system and also the proposal for reconstruction of furnace. In this contribution also a description of some ways for improvement of heating was made. The main contribution is the proposal of an adaptive system

Kostúr, K.

2006-01-01

64

Optimal Design of Flatness Control of Six High Single-Stand Cold Rolling Mill  

Directory of Open Access Journals (Sweden)

Full Text Available The key control model for cold rolling, i.e., the so-called flatness control systems for six high cold rolling mill is investigated deeply and a kind of optimal design is obtained. The overall flatness control system consists of the sub-system of flatness signal processing and the sub-system of flatness optimum control. Indeed, several compensation models are included in the sub-system of flatness signal processing for releasing detecting errors, and optimal control outputs, such as skewing roll and bending roll, are calculated easily by the underlying flatness optimum control systems. All the above functional models are simulated by using the Matlab simulation software, and the effectiveness and optimum of the proposed approaches are illustrated.

Xiangpeng XIE

2014-03-01

65

Evaluation of the fatigue damage of rolls for strip mills below the surface by x-ray diffraction method  

International Nuclear Information System (INIS)

Technique of the X-ray diffraction line profile analysis has been applied to the study of fatigue damage below the surface of the work and the backup rolls of cold strip mill and the backup rolls of hot strip mill. Half value breadth has been taken as a measure of fatiguing. Fatigued zone below the surface of rolls is well correlated with the half contact length of roll, L; 0.03 L in the work roll of cold strip mill and 0.1 L in the other rolls. Changes in the half value breadth with increase in cycles of roll contact differ in accordance with the surface hardness of the rolls: continued cycling results in decrease of the half value breadth at surface in hard rolls (H sub(s) >= 60) and increase in soft rolls (H sub(s) <= 50). The technique of X-ray study of fatigue can be extended to prediction and prevention of accidental failure of rolls due to fatigue fracture such as spalling. Furthermore the amount of surface dressing at regular maintenance of rolls can be saved significantly on the basis of accurate evaluation of the depth of fatigue damaged zone. (author)

66

Determination of scrap in rolling mills using radionuclides  

International Nuclear Information System (INIS)

Metal flow in an ingot can be studied during forming by a radiometric method. A Fe and 60Co radioactive sample is placed into an opening in the ingot and the sample position in the metal being formed is determined using a scintillation detector. The labelling of decisive points on the ingot heel with radionuclides and their identification in the semifinished product after rolling are advantageous for determining the effect of the ingot weight on the amount of technological scrap with respect to the action of the decisive geometric factors of metal deformation. THe absolute amount of scrap increases parabollically with the ingot cross section. (M.S.)

67

A test process for predicting wear in high-pressure grinding rolls. Testmethode zur Bestimmung des Verschleisses an Gutbett-Walzenmuehlen  

Energy Technology Data Exchange (ETDEWEB)

High-pressure grinding rolls have found increasing application in the past years, at first in the cement industry. Wear became a important topic when this new technology was applied to other materials, which mostly are more abrasive than cement clinker. The need for quantitative prediction led to development of a wear test, which utilizes a miniaturized 'Polycom' as main equipment. Results and evaluations of the first series of investigations prove the wear test suitable for prediction of wear rates as well as for qualification of new resistant alloys. (orig.).

Knobloch, O.

1990-02-01

68

Strip/Foil Rolling Mill Stochastic Excitation Model and Its Stability  

Directory of Open Access Journals (Sweden)

Full Text Available Based on the stochastic rolling force data from aluminum hot strip tandem mill, the ARMA time series model and the stochastic excitation power spectral density (PSD model are established, and the stochastic rolling forces excitation model is established by utilizing Levenberg-Marquardt combined with generalized global planning algorithm. A two dimensional stochastic nonlinear dynamical model of rolls is presented considering the stochastic factor of the rolling force. The Hamilton function is also described as one dimension diffusion process by using stochastic average method, the singular boundary theory was taken for analyzing the global stochastic stability of the system, and the system’s stochastic stability was researched by solving the Fokker-Planck-Kolmogorov (FPK equation. The results show that the stochastic excitation model obtained has significance for analyzing and researching stochastic dynamics characteristics to the system, and also generalized energy H in the range of 0.02 to 0.4, the system’s response has the minimum transition probability density, and the system state is not easy to change, therefore the system generalized energy H should be to limit in this range in the design and operation of the rolling mill.

Baoyu Xu

2012-06-01

69

Heavy metals adsorption on rolling mill scale; Adsorcion de metales pesados sobre cascarill de laminacion  

Energy Technology Data Exchange (ETDEWEB)

A great quantity of industries are responsible for contaminating the environment with the heavy metals which are containing in their wastewaters. The recovery of these metals is both from an environmental and economical points of view of the upmost interest. A study is made of the use of mill scale-originating in the hot rolling of steel-as an adsorbent for the removal of heavy metals from liquid effluents. The adsorption of Zn''2+, Cd''2+ y Pb''2+ on the rolling mill scale was investigated by determination of adsorption isotherms. The effect of time, equilibrium temperature and concentration of metal solution on mill scale adsorption efficiency was evaluated. The adsorption process was analysed using the theories of Langmuir and Freundlich. Desorption process of metals from loaded mill scales was also studied using several doser bent at different experimental conditions. It has been proved that the mill scale is an effective adsorbent for the cations studies in aqueous solutions within the range of the working concentrations. (Author) 32 refs.

Lopez, F. A.; Martin, M. I.; Perez, C.; Lopez-Delgado, A.; Alguacil, E. J.

2003-07-01

70

Preparation Model Based Control System For Hot Steel Strip Rolling Mill Stands  

Science.gov (United States)

As part of a research project on El-hadjar Hot Steel Rolling Mill Plant Annaba Algeria a new Model based control system is suggested to improve the performance of the hot strip rolling mill process. In this paper off-line model based controllers and a process simulator are described. The process models are based on the laws of physics. these models can predict the future behavior and the stability of the controlled process very reliably. The control scheme consists of a control algorithm. This Model based Control system is evaluated on a simulation model that represents accurately the dynamic of the process. Finally the usefulness to the Steel Industry of the suggested method is highlighted.

Bouazza, S. E.; Abbassi, H. A.; Moussaoui, A. K.

2008-06-01

71

Kinetic study of the removal of Cu(II) from aqueous solutions by rolling mill scale  

International Nuclear Information System (INIS)

The removal of Cu(II) from aqueous solutions by rolling mil scale occurs through a process of oxidation-reduction or cementation of Cu''2+ ions in aqueous solution onto metallic iron (Fe''0) contained in the mill scale. The kinetics of cementation of copper onto iron was evaluated over different temperatures, initial copper concentrations and solid/liquid relations. Process of copper removal by rolling mill scale obeys a first-order kinetic law. The rate constant value (k) varies with temperature and initial cation concentration in solution at low temperatures. At high temperatures the value of k remains practically constant. the solid/liquid relation value affects the rate constant value too. (Author) 19 refs

72

Balance mathematical model for the heat regime of cold rolling of electrical steel strips in a reversing mill  

Science.gov (United States)

A mathematical model is developed to describe the heat regime of a reversing cold-rolling mill that takes into account the substantial differences between the heat processes occurring in reversing and continuous mills. Model and heat balance equations are used to calculate the strip temperature in passes and the temperature and the heat profile of rolls as functions of the rolling regime parameters and the heat-transfer coefficients that characterize the heat exchange between a strip, rolls, and lubricant-cooling agents and depend on the cooling system parameters of a mill. The model can be used to find a heat regime favorable for achieving the required final magnetic properties of electrical steel. The efficiency of the factors affecting the heat regime in rolling is studied.

Garber, E. A.; Aleshin, A. E.; Degtev, S. S.; Traino, A. I.

2013-11-01

73

[Effect of working conditions on myocardial contractility in tube-rolling mill workers].  

Science.gov (United States)

Tetrapolar rheography, M-echocardiography and visual searching ++Doppler echocardiography were used to study the state of the myocardium in 228 practically healthy male workers engaged in different working conditions at a tube-rolling mill. Revealed were increased myocardium and myocardium contraction disorders resulting from physical over-load in combination with heating microclimate and noise. The contributors proposed approaches to the preclinical diagnosis of such changes, which could be applied to the elaboration of preventive measures. PMID:1831780

Miller, M B

1991-01-01

74

A nucleonic thickness control system for a thin sheet rolling mills machine  

International Nuclear Information System (INIS)

A nuclear transmission thickness gauge and control system was developed. It was used to improve the thickness control of the thin sheet metal production in the cold rolling mills. The deviation from the nominal thickness of the sheet metal was reduced through automatic correction in continuous production process. The five main parts of the nuclear thickness gauge are : radiation source. radiation detection system, analog to digital converter, micro controller and interfaces. A thickness gauge with Am-241 of 3.7 x 109 Bq as radiation source together with a 1 x 1 inch NaI(T 1) as radiation detector was installed on an old version cold rolling mills producing brass sheets of various thickness from 0.1 to 0.5 mm with a feeding speed of 25 m/min. It was found that with nuclear thickness gauge the brass sheet thickness could be controlled with a deviation of ±0.01 mm in comparison with ±0.02 mm resulting from the previous conventional thickness control. Thus, the performance of the old version cold rolling mills can be improved through the development of an automatic nuclear electronic thickness gauging

75

Wireless Remote Monitoring System for the Agc Svibration Fault of Rolling Mill  

Directory of Open Access Journals (Sweden)

Full Text Available The rolling mill screw down AGC system sets several subsystems of machinery, electronics, hydraulics, controls in one. Under the action of responding extreme frequency or external disturbances, the non design objective coupling between the subsystems may be excited, and causing the most serious vibration, seriously impact product quality or even cause great destruction. Aiming at the defects in fault diagnosis and control system of the traditional rolling mill, the wireless remote monitoring system for the rolling mill AGC system vibration fault is designed in this paper. Using the advanced sensor technology, PLC and configuration software, GPRS network technology, the parallel distributed data acquisition and data processing for the key servo element and the hydraulic parameters which can characterize the fault characteristics of the system can be done. The monitoring software system platform on line of the hydraulic AGC system based on Kingview is set up for centralized real-time monitoring. According to the collected multidisciplinary parameter the fault identification and location is done by using the fault diagnosis expert system based on Web, thus to make the preliminary evaluation for the operation and fault of hydraulic AGC system and provide advanced prediction and exclude strategy.

Yan Gao

2013-01-01

76

Effect of powder milling on mechanical properties of hot-pressed and hot-rolled Cu–Cr–Nb alloy  

International Nuclear Information System (INIS)

Highlights: •Milled powder enhances sintering and mechanical properties after hot pressing. •Hot-rolling of hot-pressed samples made from milled powder enhances ductility. •Pore size and number of pores decreases after hot-rolling. -- Abstract: The present study is on the effect of mechanical milling of gas-atomized powders on mechanical properties of the hot-pressed and subsequently hot-rolled Cu–8 at% Cr–4 at% Nb alloy with a microstructure consisting of pure copper matrix hardened by intermetallic Cr2Nb precipitates. The mechanically milled powders result in lower sintering temperature during hot pressing compared to the atomized powders. The hot-pressed samples made from the milled powder exhibit significantly higher hardness and tensile strength, but lower ductility and electrical conductivity compared to that made from the un-milled gas-atomized powders. The hot rolling results in marginal increase in strength, but significant increase in ductility compared to the hot-pressed alloy for both the milled and atomized powders and it is attributed to the decrease in size of the pores and amount of porosities after hot rolling

77

Effect of powder milling on mechanical properties of hot-pressed and hot-rolled Cu–Cr–Nb alloy  

Energy Technology Data Exchange (ETDEWEB)

Highlights: •Milled powder enhances sintering and mechanical properties after hot pressing. •Hot-rolling of hot-pressed samples made from milled powder enhances ductility. •Pore size and number of pores decreases after hot-rolling. -- Abstract: The present study is on the effect of mechanical milling of gas-atomized powders on mechanical properties of the hot-pressed and subsequently hot-rolled Cu–8 at% Cr–4 at% Nb alloy with a microstructure consisting of pure copper matrix hardened by intermetallic Cr{sub 2}Nb precipitates. The mechanically milled powders result in lower sintering temperature during hot pressing compared to the atomized powders. The hot-pressed samples made from the milled powder exhibit significantly higher hardness and tensile strength, but lower ductility and electrical conductivity compared to that made from the un-milled gas-atomized powders. The hot rolling results in marginal increase in strength, but significant increase in ductility compared to the hot-pressed alloy for both the milled and atomized powders and it is attributed to the decrease in size of the pores and amount of porosities after hot rolling.

Shukla, A.K.; Narayana Murty, S.V.S.; Suresh Kumar, R. [Materials and Metallurgy Group, Vikram Sarabhai Space Centre, Trivandrum 695 022 (India); Mondal, K., E-mail: kallol@iitk.ac.in [Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

2013-12-15

78

Simulation of the thermal conditions of rolls in a wide-strip hot-rolling mill to determine their effective cooling conditions  

Science.gov (United States)

An advanced procedure is developed for the thermal calculation of the rolls in a wide-strip hot-rolling mill (WSHRM). It combines the following two adaptive models: the thermal balance in the active surface layer in a roll per revolution and the thermal balance in the main zones of work and backup rolls with axisymmetric temperature fields with allowance for the heat exchange between a strip, rolls, the coolant, and the environment. In contrast to the well-known models, this advanced procedure calculates the bulk mean temperature and the thermal profile in a roll more accurately, since the temperature drop across the surface layer in this procedure is calculated allowing for the intensities of the contact and convective heat exchange between rolls. Data on the coefficient of heat transfer from rolls to the coolant supplied at an excess pressure of 1.0-1.5 MPa are presented for the first time. This procedure is used in a 2000 WSHRM and improves the transverse profile of hot-rolled strips due to a stabilized thermal profile in rolls.

Garber, E. A.; Khlopotin, M. V.; Traino, A. I.; Popov, E. S.; Savinykh, A. F.

2009-06-01

79

Bearing restoration by grinding  

Science.gov (United States)

A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

1976-01-01

80

Simulation of the longitudinal thickness deviation of the steel strips hot rolled in the continuous group of a broad-strip mill  

Science.gov (United States)

A model for the formation of longitudinal thickness deviation in hot-rolled strips as a function of the rolling parameters and an algorithm for optimizing the rolling conditions for the criterion of the minimum longitudinal thickness deviation are developed and implemented in the form of computer programs. This optimization is performed by the redistribution of percent reductions over the stands of the finishing group in a broad-strip hot-rolling mill. As a result of the application and industrial tests of the developed computer programs on a 2000 rolling mill, the longitudinal thickness deviation of hot-rolled strips is decreased by a factor of 1.87.

Garber, E. A.; Pospelov, I. D.; Traino, A. I.; Savinykh, A. F.; Nikolaev, N. Yu.; Mishnev, P. A.

2012-09-01

 
 
 
 
81

The technology of production of high-strength, cold resistant weldable steel on wide-strip rolling mill  

International Nuclear Information System (INIS)

Regularities of influence of technological rolling parameters on wide-strip rolling mill on structure and mechanical characteristics of low-carbon steel of St3sp type were established. Possibility of sufficient growth of strength and cold resistance of strips, produced by hot working, as compared to traditional technology is shown. This is achieved by grain refinement and formation of subgrain structure in ferrite

82

Physical modelling of plastic deformation conditions for the rolling proces of AZ31 bars in a three high skew rolling mill  

Directory of Open Access Journals (Sweden)

Full Text Available The article presents results of the research concerning the physical modeling of plastic working of AZ31 magnesium alloy using two research methods. These studies were conducted using a metallurgical process simulator and torsional plastometer. The research was done for temperature range 200 ÷ 400 °C and strain rate from 0,1 to 20,0 s-1, depending on the testing method. The results allow to determine the coefficients in yield equation needed for the numerical research. Moreover the most advantageous temperature - velocity conditions to realize the process of bars rolling in three high skew rolling mill can be determined.

A. Gryc

2014-10-01

83

Finite elements method (FEM simulation based prediction of deformation and temperature at rolling of tubes on a pilgrim mill  

Directory of Open Access Journals (Sweden)

Full Text Available 3D - FEM simulation was used as an efficient tool for description of stress-deformation thermal field at rolling of tubes on a pilgrim mill. The monitored objectives comprised also behaviour of working tools at this rolling. This paper assumes rolling of already pierced thick-walled blank, which passes through the pilgrim stand at simultaneous reduction of thickness of inside and outside diameters at the expense of elongation of initial length. Main attention is focused on the mentioned parameters with respect to various conditions of rolling, such as different heat transfer, different friction or different distance of insertion of the rolled product into the gauge. The input data used at simulation were derived from real conditions of tubemaking.

R. Kocich

2009-10-01

84

Finger milling-cutter CNC generating hypoid pinion tooth surfaces based on modified-roll method and machining simulation  

Science.gov (United States)

The two coordinate systems of cradle-type hypoid generator and free-form CNC machine tool by application disc milling-cutter to generate hypoid pinion tooth surfaces based on the modified-roll method were set up, respectively, and transformation principle and method for machine-tool settings between the two coordinate systems was studied. It was presented that finger milling-cutter was mounted on imagined disc milling-cutter and its motion was controlled directly by CNC shafts to replace disc milling-cutter blades effective cutting motion. Finger milling-cutter generation accomplished by ordered circular interpolation was determined, and interpolation center, starting and ending were worked out. Finally, a hypoid pinion was virtually machined by using CNC machining simulation software VERICUT.

Li, Genggeng; Deng, Xiaozhong; Wei, Bingyang; Lei, Baozhen

2011-05-01

85

Neural compensation and modelling of a hot strip rolling mill using radial basis function  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: English Abstract in english In this paper a Neural Compensation Strategy for a hot rolling mill process is proposed. The target of this work is to built a RBF-NN compensation approximation for the classical force feed forward and speed controller. A strategy based on neural networks is proposed here, because they are capable o [...] f modelling many nonlinear systems and their neural control via RBF-NN approximation. Simulations demonstrate that the proposed solution deals with disturbances and modeling errors in a better way than classic solutions do. The analysis of the RBF-NN approximation error on the control errors is included, and control system performance is verified through simulations.

F.G., Rossomando; J., Denti F; A., Vigliocco.

86

Transport, mixing and stretching in a chaotic Stokes flow: The two-roll mill  

International Nuclear Information System (INIS)

We present the outline and preliminary results of an analytical and numerical study of transport, mixing, and stretching in a chaotic Stokes' flow in a two-roll mill apparatus. We use the theory of dynamical systems to describe the rich behavior and structure exhibited by these flows. The main features are the homoclinic tangle which functions as the backbone of the chaotic mixing region, the Smale horseshoe, and the island chains. We then use our detailed knowledge of these structures to develop a theory of transport and stretching of fluid in the chaotic regime. In particular, we show how a specific set of tools for adiabatic chaos- the adiabatic Melnikov function lobe area and flux computations and the adiabatic switching method is ideally suited to develop this theory of transport, mixing and stretching in time-dependent two-dimensional Stokes' flows. 19 refs., 8 figs

87

Steel balls forming by cross rolling with upsetting  

Directory of Open Access Journals (Sweden)

Full Text Available The paper describes a process of forming four balls with a diameter of 22 mm by means of cross rolling with upsetting. The paper also presents the tool used to form semi-finished balls. Owing to the application of the finite element method (FEM, the course of the rolling process as well as temperature and strain distributions in the obtained balls could be presented. The rolling tests conducted in laboratory conditions at the Lublin University of Technology have proved that the balls produced with the developed rolling method meet the demands for grinding media used in ball mills.

Z. Pater

2013-01-01

88

Optimising the specific energy consumption of a high compression roller mill for fine grinding of limestone. Zur Optimierung des spezifischen Energiebedarfs einer Gutbett-Walzenmuehle bei der Feinstmahlung von Kalkstein  

Energy Technology Data Exchange (ETDEWEB)

To determine the optimum specific grinding force for fine grinding of limestone, tests were conducted aimed at a particle fineness of 6 [mu]m. Here an optimum can be found at around 4.2 N/mm. A further reduction of total energy consumption is possible by subjecting the material being ground several times to mechanical action prior to air classifying, i.e. to repeat the grinding and disagglomeration step several times. By this means, the material which was not able to be comminuted after passing through the grinding process just once, but has already been subjected to mechanical action and consequently reveals microfractures and other ''defects'', is again subjected to a further mechanical action where its size can easily be reduced due to the reduced stability. In addition, the material not, or hardly, subjected to mechanical action owing to the wall effect, the proportion of which is relatively high for high compression roller mills with a relatively low length/diameter ratio of grinding rollers, can again be subjected to grinding. Tests conducted in this respect revealed that passing the material around four times though the grinding stage prior to air classifying can be considered to be favourable. (orig.)

Wehle, T. (Luleaa Univ. of Technology, Div. of Mineral Processing (Sweden)); Forssberg, E. (Luleaa Univ. of Technology, Div. of Mineral Processing (Sweden))

1994-04-01

89

Set of automatic nondestructive testing means for the quality control of pipes in production line of '140' rolling mill  

International Nuclear Information System (INIS)

Devices and installations are described forming a system of subsidiary mechanical equipment and means of automatization for testing hot-rolled ferromagnetic steel pipes in the finishing line of ''140'' pipe-rolling mill. The main features of the system are as follows: it is equipped with automatic control devices which supply objective information on the quality of the pipes; the non-destructive test equipment is automatic, thus rapid and reliable; auxiliary joints and devices are unificated, so that the separate stages of control can be quickly re-organized. A computer collects and stores information on tested pipes of the rolled lot and can supply it type-written. Computer-treated results of tests during a certain period, if analysed with regard for smelting and rolling technology, may be used as technological advice on improvement of production and may probably provide for savings on steel deformation processes

90

Study on Online Analysis of Transfer Function of Variable-Speed Rolling Mill Motor with Shaft Torsional Vibration Systems  

Science.gov (United States)

The torsional vibration between metal rolling rolls and a rolling mill motor, may occur in recent days, as a result of higher speed response adjustment for variable speed rolling mill motor drive system. Issues in this paper are focused on excess acceleration value, in tangential direction of the mill motor rotor, which is caused by the motor shaft torsional resonance at the white noise signal superposition to the speed reference signal of the motor drive system for the online transfer function analysis. As a result of the acceleration analysis, the acceleration values in “G” (Relative acceleration value on the basis of Gravity) can be plotted on “Bode-Diagram”, which is namely frequency response for the speed signal amplitude transmission ratio. In addition, relation between the white noise amplitude reduction and the transfer function analysis accuracy deterioration is also examined, in this paper. As the amplitude of the white noise decreases, the analysis error increases because of the reduction in the resolution when the amplitude of the white noise signal is small.

Tamaoki, Toshifumi; Takanezawa, Makoto; Kimoto, Masanori; Morita, Noboru; Hoshino, Takeo; Hashizume, Kenji

91

Evaluation of residual uranium contamination in the dirt floor of an abandoned metal rolling mill.  

Science.gov (United States)

A single, large, bulk sample of uranium-contaminated material from the dirt floor of an abandoned metal rolling mill was separated into different types and sizes of aliquots to simulate samples that would be collected during site remediation. The facility rolled approximately 11,000 tons of hot-forged ingots of uranium metal approximately 60 y ago, and it has not been used since that time. Thirty small mass (? 0.7 g) and 15 large mass (? 70 g) samples were prepared from the heterogeneously contaminated bulk material to determine how measurements of the uranium contamination vary with sample size. Aliquots of bulk material were also resuspended in an exposure chamber to produce six samples of respirable particles that were obtained using a cascade impactor. Samples of removable surface contamination were collected by wiping 100 cm of the interior surfaces of the exposure chamber with 47-mm-diameter fiber filters. Uranium contamination in each of the samples was measured directly using high-resolution gamma ray spectrometry. As expected, results for isotopic uranium (i.e., U and U) measured with the large-mass and small-mass samples are significantly different (p 0.05) from results for the large- or small-mass samples. Large-mass samples are more reliable for characterizing heterogeneously distributed radiological contamination than small-mass samples since they exhibit the least variation compared to the mean. Thus, samples should be sufficiently large in mass to insure that the results are truly representative of the heterogeneously distributed uranium contamination present at the facility. Monitoring exposure of workers and the public as a result of uranium contamination resuspended during site remediation should be evaluated using samples of sufficient size and type to accommodate the heterogeneous distribution of uranium in the bulk material. PMID:23274821

Glassford, Eric; Spitz, Henry; Lobaugh, Megan; Spitler, Grant; Succop, Paul; Rice, Carol

2013-02-01

92

The Physical Flow of Materials and the Associated Costs in the Production Process of a Rolling Mill  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Efficiency of resources use is, in a large extent, determined by the organization of production flow and the way of their control. The optimization of materials flow in the production process requires the identification of physical flows of goods and it cost. In the article the physical flow process of materials stream in the production process in one of Polish rolling mill and also its logistics analysis and cost analysis are presented.

Holisz-burzyn?ska, J.; Staniewska, E.; Budzik, R.

2007-01-01

93

The Physical Flow of Materials and the Associated Costs in the Production Process of a Rolling Mill  

Directory of Open Access Journals (Sweden)

Full Text Available Efficiency of resources use is, in a large extent, determined by the organization of production flow and the way of their control. The optimization of materials flow in the production process requires the identification of physical flows of goods and it cost. In the article the physical flow process of materials stream in the production process in one of Polish rolling mill and also its logistics analysis and cost analysis are presented.

Holisz-Burzy?ska, J.

2007-01-01

94

Occupational noise exposure and sensorineural hearing loss among workers of a steel rolling mill.  

Science.gov (United States)

Hearing loss is one of the most common chronic health conditions and has important implications for the patient's quality of life. However, hearing loss is substantially underestimated and under treated. The purpose of this study was to determine the prevalence of sensorineural hearing loss among the workers in a steel rolling mill in Nigeria. Each of the 150 randomly selected subjects had a structured questionnaire administered to them, followed by a full otological examination. Of these, 116 had tympanometry and pure-tone audiometry. Also a noise mapping of their respective work units was done. The workers were exposed to noise levels varying from 49 to 93 dBA. About 28.2% of the 103 who had their audiogram analysed had mild to moderate sensorineural hearing loss in their better ear and 56.8% of them had mild to moderate sensorineural hearing loss in their worse ear. The pure-tone average and the average hearing thresholds at 4 kHz for the groups significantly increased with an increasing noise exposure level. The prevalence of sensorineural hearing loss among the study population is high; and noise exposure is at least contributory. Pre-employment and regular audiometry while on the job is highly recommended. PMID:16680467

Ologe, Foluwasayo E; Akande, Tanimola M; Olajide, Toye G

2006-07-01

95

Synchronous control for the hydraulic width system of edger rolling mill  

Science.gov (United States)

Edger rolling mill is a load system in which the upper and the lower cylinder actuate a side vertical roller at the same time. Due to the linkage of the load, the output and control of two channels influence each other. Synchronic-control issue is discussed aim to the system with serious coupling. Neural network inverse as decoupling controller is proposed to account for the complicated process dynamics characterized by nonlinear, time-varying, uncertain and load couple properties. Firstly, the reversibility of the system is analyzed and the ANN inverse dynamic is constructed based on a feed forward and neural network structure with enlarged back propagation algorithm. Secondly, the system is changed into two pseudo-linear sub-system through connecting the controlled system and inverse dynamic model in series. Aim to two pseudo-linear sub-system pole assignments method is proposed to enhance the whole system performance. A series simulation was conducted and results showed the proposed controller does better than traditional PID not only on decoupling but also on the transient response, as well as robustness under vary conditions.

Ning, Shurong; Fan, Zhuoyu

2008-10-01

96

Genetic based sensorless hybrid intelligent controller for strip loop formation control between inter-stands in hot steel rolling mills.  

Science.gov (United States)

Safe operating environment is essential for all complex industrial processes. The safety issues in steel rolling mill when the hot strip passes through consecutive mill stands have been considered in this paper. Formation of sag in strip is a common problem in the rolling process. The excessive sag can lead to scrap runs and damage to machinery. Conventional controllers for mill actuation system are based on a rolling model. The factors like rise in temperature, aging, wear and tear are not taken into account while designing a conventional controller. Therefore, the conventional controller cannot yield a requisite controlled output. In this paper, a new Genetic-neuro-fuzzy hybrid controller without tension sensor has been proposed to optimize the quantum of excessive sag and reduce it. The performance of the proposed controller has been compared with the performance of fuzzy logic controller, Neuro-fuzzy controller and conventional controller with the help of data collected from the plant. The simulation results depict that the proposed controller has superior performance than the other controllers. PMID:18093589

Thangavel, S; Palanisamy, V; Duraiswamy, K

2008-04-01

97

Online Prediction Under Model Uncertainty via Dynamic Model Averaging: Application to a Cold Rolling Mill.  

Science.gov (United States)

We consider the problem of online prediction when it is uncertain what the best prediction model to use is. We develop a method called Dynamic Model Averaging (DMA) in which a state space model for the parameters of each model is combined with a Markov chain model for the correct model. This allows the "correct" model to vary over time. The state space and Markov chain models are both specified in terms of forgetting, leading to a highly parsimonious representation. As a special case, when the model and parameters do not change, DMA is a recursive implementation of standard Bayesian model averaging, which we call recursive model averaging. The method is applied to the problem of predicting the output strip thickness for a cold rolling mill, where the output is measured with a time delay. We found that when only a small number of physically motivated models were considered and one was clearly best, the method quickly converged to the best model, and the cost of model uncertainty was small; indeed DMA performed slightly better than the best physical model. When model uncertainty and the number of models considered were large, our method ensured that the penalty for model uncertainty was small. At the beginning of the process, when control is most difficult, we found that DMA over a large model space led to better predictions than the single best performing physically motivated model. We also applied the method to several simulated examples, and found that it recovered both constant and time-varying regression parameters and model specifications quite well. PMID:20607102

Raftery, Adrian E; Kárný, Miroslav; Ettler, Pavel

2010-02-01

98

STUDIES ON CONTINUOUS GRINDING PROCESS FOR DRIED WATER CHESTNUT KERNEL  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Grinding is a unit operation to break big solid material into smaller pieces. As far as process of grinding is concerned, power consumption, specific energy consumption and particle size distribution and mill capacity are main considerations from engineering point of view. The experiments were conducted to study the effect of speed of mill, sieve size, feed rate and time of grinding on power consumption and average particle diameter of water chestnut in continuous grinding process. Power cons...

Garg, S. K.; Lohani, U. C.; Pandey, J. P.

2010-01-01

99

MOLIENDA DE CLINKER DE CEMENTO: EVALUACIÓN DE LA INFLUENCIA DE LA VELOCIDAD DE GIRO DEL MOLINO, EL TIEMPO DE RESIDENCIA Y LA CARGA DE LOS MEDIOS DE MOLIENDA / CEMENT CLINKER GRINDING: EVALUATION OF MILL SPIN SPEED, RESIDENCE TIME AND GRINDING MEDIA LOAD  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish se evaluó la molienda de clinker en molino de bolas, variando: velocidad del molino (24 y 72 RPM), tiempo de residencia (3 y 5 horas) y carga de cuerpos moledores (30 y 40 %), mediante un modelo factorial, el objetivo fue evaluar la incidencia de estos sobre el porcentaje másico pasante 45 micras y [...] el área superficial, factores determinantes en la calidad del cemento comercial. Se determinaron propiedades fisicoquímicas, de composición, naturaleza mineralógica y distribución granulométrica del material empleando Fluorescencia de Rayos X, Análisis de Área Superficial y Análisis Granulométrico por Tamizado. Se encontró que la cantidad de masa pasante de 45 micras crece al aumentar la velocidad del molino y en menor proporción al incrementar el tiempo, y que el cambio de carga de cuerpos moledores resulta insignificante. El área superficial aumenta al incrementarse velocidad, tiempo y carga; no obstante estos últimos en proporción menor que con la velocidad. Abstract in english In this study, the milling of clinker was evaluated by varying the mill speed (24 and 72 RPM), residence time (3 and 5 hours) and grinding media load (30 and 40 %) in a ball mill. The experiment was designed as a three level factorial statistical model. The main objective was to assess the effect of [...] these parameters on cumulative passing percentage (CPP) and surface area, both of which affect the quality of commercial cement. Physico-chemical properties, composition, mineralogy and granulometric distribution were determined using X Ray Fluorescence, Surface Area Analysis and Sieving Granulometric Analysis. Results showed that that CPP through a 325 mesh increases considerably with mill spin speed, that the rate of CPP increase decreases with residence time and that grinding media load changes were not significant. The surface area increased mainly as a function of increases in mill spin speed, while residence time and grinding media load had lesser impacts.

ADRIANA, OSORIO; GLORIA, RESTREPO; JUAN, MARÍN.

100

Catalytic surface modification of roll-milled poly({epsilon}-caprolactone) biaxially stretched to ultra-thin dimension  

Energy Technology Data Exchange (ETDEWEB)

A novel roll-milling polymer processing technique along with biaxial stretching was used to fabricate 10 {mu}m thick poly({epsilon}-caprolactone) films. A less invasive collagen surface modification was used, involving a reaction between corona-preactivated membranes and ferrous-containing acrylic acid solution at the low temperature of 42 {sup o}C. Successful modified films were characterized by Toluidine Blue O assay and X-ray photoelectron spectroscopy. Human umbilical vein endothelial cells also showed both higher proliferation rate and differentiated cobblestone morphology on these collagen-immobilized substrates.

Foo, H.L. [Graduate Programme in Bioengineering, National University of Singapore (Singapore); Bionic Materials Technology Group, Biomaterials Center, National Institute for Materials Science (Japan); Taniguchi, A. [Bionic Materials Technology Group, Biomaterials Center, National Institute for Materials Science (Japan); Yu, H. [Graduate Programme in Bioengineering, National University of Singapore (Singapore); Department of Physiology, National University of Singapore (Singapore); Okano, T. [Bionic Materials Technology Group, Biomaterials Center, National Institute for Materials Science (Japan); Institute of Biomedical Engineering, Tokyo Women' s Medical University (Japan); Teoh, S.H. [Graduate Programme in Bioengineering, National University of Singapore (Singapore) and Department of Mechanical Engineering, National University of Singapore (Singapore)]. E-mail: mpetsh@nus.edu.sg

2007-03-15

 
 
 
 
101

Planejamento e controle da produção de cilindros para laminação: um estudo de caso quantitativo / Production management of rolling mill rolls: a quantitative study case  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho apresenta um modelo de otimização-simulação aplicado em um estudo de caso real no setor de cilindros para laminação de uma siderúrgica, buscando melhorar o gerenciamento da área/equipamento gargalo da linha de produção. A simulação atuou em conjunto com um modelo de otimização da progr [...] amação linear inteira (PLI) para melhorar o atendimento de prazo junto aos clientes em uma produção não seriada. Como resultado deste procedimento combinado da PLI e simulação, o processo produtivo foi otimizado e as filas de espera e o lead-time foram reduzidos, melhorando o atendimento aos clientes. Abstract in english This article presents a simulation-optimization model application for a real case study in the rolling mill roll sector of a steel plant. The purpose of this study was to get a better area/equipment bottleneck management in the production line. The simulation was used together with an ILP (Integer L [...] inear Programming) optimization model, in order to improve customer service in a made-to-order production. As a result of this ILP and Simulation combined approach, the productive process was optimized and both queues and lead-time were reduced, improving customer service.

Laerte José, Fernandes; Luis Alberto Osés, Rodriguez; Anderson Ribeiro, Correia; Fernando Augusto Silva, Marins.

2013-03-01

102

Creep feed grinding: Advanced profile grinding technology  

Science.gov (United States)

Two variants of profile grinding, reciprocate grinding and creep feed grinding, are described and compared in terms of metal removal capacity, grinding force, wheel wear, heat generation, and surface finish. Methods of continuous dressing are also discussed. Finally, the design and production advantages of continuous path controlled (feed controlled) dressing and grinding techniques are examined.

Petersen, U.

103

Maintenance strategy for tilting table of rolling mill based on reliability considerations  

International Nuclear Information System (INIS)

Reliability centred maintenance (RCM) is a new strategic framework for ensuring that any asset continues to perform, as its users want it to perform. RCM is a process used to determine the maintenance requirement of any physical asset in its operating context. RCM process entails asking seven questions about each of the selected assets. It makes use of two documents namely, RCM information worksheet and RCM decision worksheet. RCM decision diagram integrates all the decision processes into a single strategic framework. RCM concept developed by US commercial airlines industry has been successfully implemented by Military, Navy, Nuclear power plants, electric power generation and distribution undertakings and several other sectors. These projects have been carried out in the United Kingdom, The Republic of Ireland, the United States, Hong Kong, Australia, Spain and Singapore. The fact that people has enthusiastically received RCM at all levels and has enabled users to achieve some remarkable successes in all of these countries, suggests that it can be universally employed. Literature review indicates that RCM approach is not conventionally applied in process industries in India. Presently, predictive maintenance (PDM) approach along with conventional preventive maintenance is used in continuous/process industries. This approach if implemented in totality will increase the production cost to a large degree and make the production uneconomical. Similarly breakdown maintenance (BDM) approach cannot be applied in such industries as each breakdown involves huge costs. RCM approach is a compromise between PDM and BDM approach for optimising the cost and ensuring the availability of machine. The RCM approach has been applied to the tilting table system of rolling mill for the research work reported in this paper. In the present study, preventive maintenance tasks suggested for power transmission subsystem, guiding and transportation subsystem and hydraulic subsystem in tilting tables are 14 scheduled on-condition tasks, 10 scheduled on-restoration tasks, seven scheduled discard task. Whereas for 14 failure modes no scheduled maintenance has been proposed. Existing maintenance schedule for tilting tables indicates the maintenance action as and when required. Hence RCM based schedule specifies that additional preventive maintenance tasks need to be executed as compared to none initially. Cost incurred for this can be offset from the savings accrued from reduction in loss of production due to repetitive breakdowns. The methodology of RCM adopted in western industries cannot be applied as it is to Indian industries because of labour oriented nature, partially computerised information systems, non-availability of the information about cost of loss of production due to breakdown and age-reliability pattern of equipment, insufficient maintenance database. These problems can be overcome by development of sound MMIS, formulation of RCM review group and imparting suitable training to acquire the relevant skills in RCM. Thus RCM methodology can be applied to Indian industry for reduction of breakdowns as well as optimisation of preventive maintenance cost. This can further boost up the prospects of Indian industry to offer the products at globally competitive prices

104

Maintenance strategy for tilting table of rolling mill based on reliability considerations  

Energy Technology Data Exchange (ETDEWEB)

Reliability centred maintenance (RCM) is a new strategic framework for ensuring that any asset continues to perform, as its users want it to perform. RCM is a process used to determine the maintenance requirement of any physical asset in its operating context. RCM process entails asking seven questions about each of the selected assets. It makes use of two documents namely, RCM information worksheet and RCM decision worksheet. RCM decision diagram integrates all the decision processes into a single strategic framework. RCM concept developed by US commercial airlines industry has been successfully implemented by Military, Navy, Nuclear power plants, electric power generation and distribution undertakings and several other sectors. These projects have been carried out in the United Kingdom, The Republic of Ireland, the United States, Hong Kong, Australia, Spain and Singapore. The fact that people has enthusiastically received RCM at all levels and has enabled users to achieve some remarkable successes in all of these countries, suggests that it can be universally employed. Literature review indicates that RCM approach is not conventionally applied in process industries in India. Presently, predictive maintenance (PDM) approach along with conventional preventive maintenance is used in continuous/process industries. This approach if implemented in totality will increase the production cost to a large degree and make the production uneconomical. Similarly breakdown maintenance (BDM) approach cannot be applied in such industries as each breakdown involves huge costs. RCM approach is a compromise between PDM and BDM approach for optimising the cost and ensuring the availability of machine. The RCM approach has been applied to the tilting table system of rolling mill for the research work reported in this paper. In the present study, preventive maintenance tasks suggested for power transmission subsystem, guiding and transportation subsystem and hydraulic subsystem in tilting tables are 14 scheduled on-condition tasks, 10 scheduled on-restoration tasks, seven scheduled discard task. Whereas for 14 failure modes no scheduled maintenance has been proposed. Existing maintenance schedule for tilting tables indicates the maintenance action as and when required. Hence RCM based schedule specifies that additional preventive maintenance tasks need to be executed as compared to none initially. Cost incurred for this can be offset from the savings accrued from reduction in loss of production due to repetitive breakdowns. The methodology of RCM adopted in western industries cannot be applied as it is to Indian industries because of labour oriented nature, partially computerised information systems, non-availability of the information about cost of loss of production due to breakdown and age-reliability pattern of equipment, insufficient maintenance database. These problems can be overcome by development of sound MMIS, formulation of RCM review group and imparting suitable training to acquire the relevant skills in RCM. Thus RCM methodology can be applied to Indian industry for reduction of breakdowns as well as optimisation of preventive maintenance cost. This can further boost up the prospects of Indian industry to offer the products at globally competitive prices.

Deshpande, V.S.; Modak, J.P

2003-04-01

105

"Grinding" cavities in polyurethane foam  

Science.gov (United States)

Grinding tool installed on conventional milling machine cuts precise cavities in foam blocks. Method is well suited for prototype or midsize production runs and can be adapted to computer control for mass production. Method saves time and materials compared to bonding or hot wire techniques.

Brower, J. R.; Davey, R. E.; Dixon, W. F.; Robb, P. H.; Zebus, P. P.

1980-01-01

106

Grain refinement of magnesium alloy sheets by ARB using high-speed rolling mill  

Science.gov (United States)

Applications of ARB to magnesium alloys were limited due to low deformability. The authors recently found that the rollability of the alloys is significantly improved in highspeed rolling. It is supposed that the severe plastic deformation of magnesium alloy sheets is feasible if rolling in ARB processes is conducted at high speed. In this study, AZ31B and ZK60A sheets are processed by ARB up to five cycles at 423K with a speed of 1000m/min. Vickers hardness increases with increasing number of ARB cycles, while the tensile strength shows the maximum after the second cycle. The grain size is reduced significantly at the first cycle and decreases gradually from the second cycle. The mean grain sizes after five cycles are 1.6?m for AZ31B and 1.8?m for ZK60A. It is concluded that ARB using high-speed rolling is effective for grain refinement of magnesium alloys.

Utsunomiya, Hiroshi; Izumi, Ken-ichi; Sakai, Tetsuo; Mukai, Toshiji

2009-05-01

107

Grain refinement of magnesium alloy sheets by ARB using high-speed rolling mill  

International Nuclear Information System (INIS)

Applications of ARB to magnesium alloys were limited due to low deformability. The authors recently found that the rollability of the alloys is significantly improved in highspeed rolling. It is supposed that the severe plastic deformation of magnesium alloy sheets is feasible if rolling in ARB processes is conducted at high speed. In this study, AZ31B and ZK60A sheets are processed by ARB up to five cycles at 423K with a speed of 1000m/min. Vickers hardness increases with increasing number of ARB cycles, while the tensile strength shows the maximum after the second cycle. The grain size is reduced significantly at the first cycle and decreases gradually from the second cycle. The mean grain sizes after five cycles are 1.6?m for AZ31B and 1.8?m for ZK60A. It is concluded that ARB using high-speed rolling is effective for grain refinement of magnesium alloys.

108

Nanostructured MgH2 obtained by cold rolling combined with short-time high-energy ball milling  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english MgH2 was processed by short time high-energy ball milling (BM) and cold rolling (CR). A new alternative processing route (CR + BM) using the combination of CR followed by short time BM step was also applied. The effects on the final morphology, crystalline structure and H-sorption properties were ev [...] aluated. The CR + BM processing (compared to BM and CR process) resulted in an inhomogeneous particle size distribution and the biggest crystallite size of MgH2, showing that there is a clear dependence between the size/shape of the particles which compose the starting material and the efficiency of crystallite size reduction during the BM process. On the other hand, we observed that a short BM step improved the kinetic properties of the cold rolled material. It shows that the particle size reduction of MgH2 obtained by CR combined with the increase in specific surface area attained by short BM step could be key factors to allow the use of the CR + BM route.

Ricardo, Floriano; Daniel Rodrigo, Leiva; Stefano, Deledda; Bjørn Christian, Hauback; Walter José, Botta.

2013-02-01

109

Nanostructured MgH2 obtained by cold rolling combined with short-time high-energy ball milling  

Directory of Open Access Journals (Sweden)

Full Text Available MgH2 was processed by short time high-energy ball milling (BM and cold rolling (CR. A new alternative processing route (CR + BM using the combination of CR followed by short time BM step was also applied. The effects on the final morphology, crystalline structure and H-sorption properties were evaluated. The CR + BM processing (compared to BM and CR process resulted in an inhomogeneous particle size distribution and the biggest crystallite size of MgH2, showing that there is a clear dependence between the size/shape of the particles which compose the starting material and the efficiency of crystallite size reduction during the BM process. On the other hand, we observed that a short BM step improved the kinetic properties of the cold rolled material. It shows that the particle size reduction of MgH2 obtained by CR combined with the increase in specific surface area attained by short BM step could be key factors to allow the use of the CR + BM route.

Ricardo Floriano

2013-02-01

110

Nanostructured MgH2 obtained by cold rolling combined with short-time high-energy ball milling  

Directory of Open Access Journals (Sweden)

Full Text Available MgH2 was processed by short time high-energy ball milling (BM and cold rolling (CR. A new alternative processing route (CR + BM using the combination of CR followed by short time BM step was also applied. The effects on the final morphology, crystalline structure and H-sorption properties were evaluated. The CR + BM processing (compared to BM and CR process resulted in an inhomogeneous particle size distribution and the biggest crystallite size of MgH2, showing that there is a clear dependence between the size/shape of the particles which compose the starting material and the efficiency of crystallite size reduction during the BM process. On the other hand, we observed that a short BM step improved the kinetic properties of the cold rolled material. It shows that the particle size reduction of MgH2 obtained by CR combined with the increase in specific surface area attained by short BM step could be key factors to allow the use of the CR + BM route.

Ricardo Floriano

2012-01-01

111

Finite element analysis of edge fracture of electrical steel strip in reversible cold rolling mill  

Energy Technology Data Exchange (ETDEWEB)

An electrical steel strip is commonly used as a core material in all types of electric transformers and motors. It is produced by a cold rolling process. In this paper, a damage mechanics based approach that predicts the edge fracture of an electrical steel strip during cold rolling is presented. We adopted the normal tensile stress criterion and the fracture energy method as a damage initiation criterion and a damage evolution scheme, respectively. We employed finite element analysis (FEA) to simulate crack initiation and propagation at the initial notch located at the edges of the strip. The material constants required in FEA were experimentally obtained by tensile tests using a standard and a notched sheet type specimen. The results reveal that the edge crack was initiated at the entrance of the roll bite and that it rapidly evolved at the exit. The evolution length of the edge crack increased as the length of the initial notch as well as front tension reel force of the strip increased.

Byon, Sang Min [Dong A Univ., Busan (Korea, Republic of)

2012-12-15

112

Strip thickness estimation in rolling mills from electrical variables in AC drives  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: English Abstract in english The large-scale utilization of steel in the modern society highlights the importance of the lamination process, and poses new demands for advanced technologies in the electromechanical equipments as well as for the control systems. Several process parameters, such as strip thickness, friction, tensi [...] on, temperature, and rolling speed have a strong influence in the quality of the final product, and strategic importance in the control system. This paper introduces a method to obtain the torque and rolling mechanical power estimates in real time, without utilization of lamination process models. In contrast to existing techniques, in this work these estimates are derived from stator electrical variables, readily available in AC drives. This work also discusses the utilization of the torque and rolling mechanical power estimates to determine input and output strip thickness, by means of a neural network. Simulation results are presented and compared to real industrial data to demonstrate the validity of the proposed technique.

N.S., Marcellos; J.F., Denti; G.C.D., Sousa.

113

Finite element analysis of edge fracture of electrical steel strip in reversible cold rolling mill  

International Nuclear Information System (INIS)

An electrical steel strip is commonly used as a core material in all types of electric transformers and motors. It is produced by a cold rolling process. In this paper, a damage mechanics based approach that predicts the edge fracture of an electrical steel strip during cold rolling is presented. We adopted the normal tensile stress criterion and the fracture energy method as a damage initiation criterion and a damage evolution scheme, respectively. We employed finite element analysis (FEA) to simulate crack initiation and propagation at the initial notch located at the edges of the strip. The material constants required in FEA were experimentally obtained by tensile tests using a standard and a notched sheet type specimen. The results reveal that the edge crack was initiated at the entrance of the roll bite and that it rapidly evolved at the exit. The evolution length of the edge crack increased as the length of the initial notch as well as front tension reel force of the strip increased

114

Grain refinement of magnesium alloy sheets by ARB using high-speed rolling mill  

Energy Technology Data Exchange (ETDEWEB)

Applications of ARB to magnesium alloys were limited due to low deformability. The authors recently found that the rollability of the alloys is significantly improved in highspeed rolling. It is supposed that the severe plastic deformation of magnesium alloy sheets is feasible if rolling in ARB processes is conducted at high speed. In this study, AZ31B and ZK60A sheets are processed by ARB up to five cycles at 423K with a speed of 1000m/min. Vickers hardness increases with increasing number of ARB cycles, while the tensile strength shows the maximum after the second cycle. The grain size is reduced significantly at the first cycle and decreases gradually from the second cycle. The mean grain sizes after five cycles are 1.6{mu}m for AZ31B and 1.8{mu}m for ZK60A. It is concluded that ARB using high-speed rolling is effective for grain refinement of magnesium alloys.

Utsunomiya, Hiroshi; Izumi, Ken-ichi; Sakai, Tetsuo [Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Mukai, Toshiji [Structural Metals Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)], E-mail: uts@mat.eng.osaka-u.ac.jp

2009-05-01

115

Energy Use of Fine Grinding in Mineral Processing  

Science.gov (United States)

Fine grinding, to P80 sizes as low as 7 ?m, is becoming increasingly important as mines treat ores with smaller liberation sizes. This grinding is typically done using stirred mills such as the Isamill or Stirred Media Detritor. While fine grinding consumes less energy than primary grinding, it can still account for a substantial part of a mill's energy budget. Overall energy use and media use are strongly related to stress intensity, as well as to media size and quality. Optimization of grinding media size and quality, as well as of other operational factors, can reduce energy use by a factor of two or more. The stirred mills used to perform fine grinding have additional process benefits, such as polishing the mineral surface, which can enhance recovery.

de Bakker, Jan

2013-12-01

116

Surface finishing and levelling of thermomechanically hardened rolled steel  

International Nuclear Information System (INIS)

The finishing of high-strength merchant shapes from alloy steel was tried out under industrial conditions with the equipment of metallurgical plants. After thermomechanical hardening in the production line of the rolling mill, 30KhGSN2A and 40Kh1NVA steel rounds 32 and 31 mm in diameter were straightened on a two-roller straightening machine designed by the All-Union Scientific Research Institute for Metallurgical Machinery (VNII Metmash). This made possible subsequent turning and grinding of the rods. The conditions of straightening, turning and grinding have been worked so as to obtain thermomechanically strengthened and ground rolled products approximating the gauged and ground metal in shape geometry and surface finish. It is shown that the labour-consuming operation of turning can be eliminated by reducing the machining pass of the rolled product, and this lowers the labour required for the finishing operations by 75%. After grinding with 40- and 25-grain abrasive wheels, high strength rolled shapes were obtained with a diameter of 30-0.20 mm and a surface finish of class 6-5 satisfying the technical specifications. (author)

117

Design of two bearings with sealing system for the top roll shaft of sugar cane mill  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish Las chumaceras de bronce utilizadas actualmente en los molinos de caña de azúcar presentan elevado desgaste debido, entre otros factores, a la materia extraña que ingresa en ella cuando el eje superior se eleva (flota) por efecto del colchón de caña que pasa entre las mazas y al sobrecalentamiento c [...] ausado por fallas en los sistemas de lubricación y refrigeración. Con el objetivo de solucionar estos problemas dos diseños de chumaceras fueron realizados: uno con refrigeración en la caja y otro con refrigeración en la teja, ambos usando un sistema de sellado. Análisis por Elementos Finitos del comportamiento mecánico y térmico de los diseños garantiza un buen desempeño en operación. Abstract in english The bronze bearings currently used in sugar cane mills undergo an excessive wear due to both, the extraneous matter entering in the bearing gap when the shaft lift by effect of cane passing through the mill and heating caused by failures in both the lubrication and the refrigeration systems. In orde [...] r to solve this problems two bearing were designed: one cooled in the box and other cooled in the roofing tile, both using a sealing system. Finite Elements Analysis of the designs showed that they will have a good mechanical and thermal performance.

Walter, Mora Perdomo; John Sandro, Rivas Murillo; John Jairo, Coronado Marín.

118

Assessment of air pollution and its effects on the health status of the workers in beam rolling mills factory (Iran National Steel Industrial Group) from Ahvaz-Iran  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Air pollutants of iron- and steel-making operations have historically been an environmental and health hazard. These pollutants include gaseous substances such as sulfur oxide, nitrogen dioxide, and carbon monoxide. The Iran National Steel Industrial Group beam rolling mills factory has two production lines viz. line 630 and line 650, with different beam production capabilities and is capable of producing different types of beams. Materials and Methods: A retrospe...

2009-01-01

119

Using Variable Perturbation Method to Study the Stability of Torsional Self-Excited Vibration in Main Drive System of Rolling Mill  

Directory of Open Access Journals (Sweden)

Full Text Available The self-excited vibration of blooming mill is a kind of torsional vibration, which occurs only when the rolling machine slips under appropriate conditions. Once in place, this may cause the larger peak pressure of each component in the main drive system; reduce the service life of the components, cause components? damage directly. A large number of studies have shown that, at present there are not effective methods for diagnosis, monitoring of slipping and take proper measures in time to stop slipping so as to avoid the occurrence of malignant accidents. In this paper, author set out from another angle, take the main drive system of rolling mill as an example, to study stability of self-excited vibration. The conditions of the stable vibration are gained. By combining with the actual working conditions of blooming mill, author has put forward some effective measures to meet the stable conditions in order to make the blooming mill work in the stable state. Practice research has proved that the effective measures can contribute to reduce structural damage directly caused by the torsional vibration when “slipping” phenomenon occurred and to extend the service life of the components.

Fenglan Wang

2013-06-01

120

Cylindrical plunge grinding of difficult to grind materials  

International Nuclear Information System (INIS)

Cylindrical plunge grinding processes of titanium alloy and nickel-base superalloys with various kinds of conventional grinding wheels, which are known as difficult to grind materials, are experimentally investigated, analyzing size generation process, grinding force, surface roughness, wheel wear, grinding ratio and so on. For grinding titanium alloy Ti-6Al-4V, GC grinding wheel yields most superior grinding results which leads to lower grinding force, smaller residual stock, less wheel wear and higher grinding ratio up to about 3 with GC 80 L 9 V wheel. Then, for grinding nickelbase superalloys Waspaloy and Rene 41, WA 150 L 9 V wheel yields better grinding results in surface roughness, wheel wear, grinding ratio without chatter vibration though grinding force is higher, and the grinding ratio about 3 is obtained. Furthermore, higher plunge speed and speed ratio result in higher grinding efficiency though grinding force, surface roughness, wheel wear increase for grinding titanium alloy and nickel-base superalloys. (author)

 
 
 
 
121

Pitt Mill Demonstration  

Energy Technology Data Exchange (ETDEWEB)

Results of a technical and economic evaluation of application of the Pitt Mill to fine coal grinding are presented. The Pitt Mill is a vertically oriented, batch operated, intermediate energy density (0. 025 kW/lb media), stirred ball mill. The mill grinds coal from coarse sizes (typically 3/16 inch or 4 mesh topsize) to the 10 micron to 20 micron mean particle diameter size range in a single step using a shallow grinding bed containing inexpensive, readily available, course grinding media. Size reduction is efficient because of rapid product circulation through the grinding bed caused by action of a novel circulation screw mounted on the agitator shaft. When a dispersant is employed, the grinding can be carried out to 50% to 60% solids concentration. Use of coarse grinding media offers the possibility of enhanced mineral liberation because size reduction is achieved more by impact shattering than by attrition. The batch method offers the possibility of very close control over product particle size distribution without overproduction of fines. A two- phase program was carried out. In the first phase, Grinding Studies, tests were run to determine a suitable configuration of the Pitt Mill. Machine design parameters which were studied included screw configuration, media type, agitator RPM, time, media size, and slurry chamber aspect ratio. During the last part of this phase of the program, tests were carried out to compare the results of grinding Pocahontas seam, Pittsburgh {number sign}8, and East Kentucky Mingo County coals by the Pitt Mill and by a two-stage grinding process employing a Netzsch John mill to feed a high energy density (0.05 kW/Lb media) disc mill. 22 refs., 25 tabs.

Oder, R.R.; Borzone, L.A.

1990-05-01

122

Effect of the microstructure on tribological phenomena occurring on the surface of a mill roll made of SA5T cast iron (GJSL-HV600 - GJSL-330NiMoCr12-8-3  

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with the role of the microstructure in the tribological wear processes occurring in a cast iron mill roll. For this purpose, a piece of a broken roll, made in Italy, was collected. Its microstructure consisted of modular graphite, transformed ledeburite and a matrix composed of bainite and martensite. Metallographic investigations were performed on the roll working surface in conjunction with metallographic tests effected within its surface layer. There was established the relation between the microstructure of the roll and the process of its tribological wear. The following was ascertained: micro-shrinkages or graphite precipitations nearby the working area cause cracks between those places and the working area; in the surface layer, cracks occur usually in the zone of ledeburitic cementite. At places of considerable precipitations of ledeburitic cementite, the tribological wear intensity of the roll is lower. A banded layout of precipitations of ledeburitic cementite facilitates a selective spalling of some parts of the roll material. The results of this study allow broadening the data base related to the effect of the microstructure on tribological wear of mill rolls, which in future will permit one to design their proper microstructure of cast iron mill rolls.

J. Krawczyk

2008-07-01

123

AISI/DOE Advanced Process Control Program Vol. 3 of 6: MICROSTRUCTURAL ENGINEERING IN HOT-STRIP MILLS Part 2 of 2: Constitutive Behavior Modeling of Steels Under Hot-Rolling Conditions  

Energy Technology Data Exchange (ETDEWEB)

This report describes the development of models for predicting (1) constitutive behaviors and (2) mechanical properties of hot-rolled steels as functions of chemical composition, microstructural features, and processing variables. The study includes the following eight steels: A36, DQSK, HSLA-V, HSLA-Nb, HSLA-50/Ti-Nb, and two interstitial-free (IF) grades. These developed models have been integrated into the Hot-Strip Mill Model (HSMM), which simulates the hot strip rolling mills and predicts the mechanical properties of hot-rolled products. The HSMM model has been developed by the University of British Columbia-Canada as a part of project on the microstructural engineering in hot-strip mills.

Yi-Wen Cheng; Patrick Purtscher

1999-07-30

124

Estudo de variabilidade e otimização do circuito de moagem SAG da Usina do Sossego / Optimization of the Sossego SAG mill grinding circuit  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A Mina do Sossego, localizada na região sudeste do Estado do Pará, foi a primeira usina da Vale a operar um moinho SAG para processar minério de cobre e ouro. Nos primeiros três anos de operação, foram estudadas alternativas para aumento de produção, principalmente focadas em aspectos operacionais d [...] a moagem SAG. Em seguida, foram realizados estudos visando a identificar o desempenho do circuito em função dos diferentes tipos de minérios alimentados. Uma caracterização completa do minério foi realizada em conjunto com a calibração de modelos matemáticos baseados em amostragens conduzidas no circuito industrial. O simulador foi então usado para prever níveis de produção associados a cada tipo de minério, assim como determinar configurações otimizadas para o circuito. Esse artigo descreve em detalhes os principais aspectos da otimização do circuito, assim como o método para prever a produção em função das características do minério e do circuito. Abstract in english Sossego was the first Vale SAG mill operation to process copper-gold ore. It is located in the State of Para, southeastern Amazon region of Brazil. In the first three years of continuous operation, Vale investigated different alternatives for improving the circuit’s performance by investigating oper [...] ating conditions, mainly focusing on the SAG mill. It was decided to further assess the performance of the comminution circuit as a function of ore characteristics. A comprehensive ore characterization program was then conducted, together with the calibration of mathematical models on the basis of surveys carried out at the industrial circuit. The simulator was then used to predict the throughput associated to each ore type, as well as to establish the optimized circuit configuration and tailored operating conditions. This paper describes in detail the main aspects of optimizing the industrial circuit performance, as well as the successful method for predicting the production as a function of ore characteristics and circuit configuration.

Maurício, Bergerman; Homero, Delboni; Marco, Nankran.

125

Estudo de variabilidade e otimização do circuito de moagem SAG da Usina do Sossego Optimization of the Sossego SAG mill grinding circuit  

Directory of Open Access Journals (Sweden)

Full Text Available A Mina do Sossego, localizada na região sudeste do Estado do Pará, foi a primeira usina da Vale a operar um moinho SAG para processar minério de cobre e ouro. Nos primeiros três anos de operação, foram estudadas alternativas para aumento de produção, principalmente focadas em aspectos operacionais da moagem SAG. Em seguida, foram realizados estudos visando a identificar o desempenho do circuito em função dos diferentes tipos de minérios alimentados. Uma caracterização completa do minério foi realizada em conjunto com a calibração de modelos matemáticos baseados em amostragens conduzidas no circuito industrial. O simulador foi então usado para prever níveis de produção associados a cada tipo de minério, assim como determinar configurações otimizadas para o circuito. Esse artigo descreve em detalhes os principais aspectos da otimização do circuito, assim como o método para prever a produção em função das características do minério e do circuito.Sossego was the first Vale SAG mill operation to process copper-gold ore. It is located in the State of Para, southeastern Amazon region of Brazil. In the first three years of continuous operation, Vale investigated different alternatives for improving the circuit’s performance by investigating operating conditions, mainly focusing on the SAG mill. It was decided to further assess the performance of the comminution circuit as a function of ore characteristics. A comprehensive ore characterization program was then conducted, together with the calibration of mathematical models on the basis of surveys carried out at the industrial circuit. The simulator was then used to predict the throughput associated to each ore type, as well as to establish the optimized circuit configuration and tailored operating conditions. This paper describes in detail the main aspects of optimizing the industrial circuit performance, as well as the successful method for predicting the production as a function of ore characteristics and circuit configuration.

Maurício Bergerman

2009-03-01

126

STUDIES ON CONTINUOUS GRINDING PROCESS FOR DRIED WATER CHESTNUT KERNEL  

Directory of Open Access Journals (Sweden)

Full Text Available Grinding is a unit operation to break big solid material into smaller pieces. As far as process of grinding is concerned, power consumption, specific energy consumption and particle size distribution and mill capacity are main considerations from engineering point of view. The experiments were conducted to study the effect of speed of mill, sieve size, feed rate and time of grinding on power consumption and average particle diameter of water chestnut in continuous grinding process. Power consumption was measured for a constant feed rate of 1 and 2 kg/h at different speed of the mill varied from 800 to 1200 rpm for the sieve openings of 0.5 mm, 1.0 mm and 2.0 mm. For all the sieve sizes and feed rates, it was observed that as the speed of the mill increases, there is an increase in power consumption and found significantly low for higher sieve size and lower feed rate. The size distribution of the water chestnut kernel for different speeds and sieve sizes at constant feed rate were obtained by sieve analysis. The milling speed has no significant effect on particle size distribution of ground product and mass fraction was minimum at lower feed rate and higher sieve size. Harris model was found best suitable to describe the size distribution in continuous grinding process. Fineness modulus decreases with increase of milling speed for experimental sieve size and feed rate.

S.K. GARG

2010-06-01

127

Ultrafine grinding using a fluidized bed opposed jet mill: effects of feed load and rotational speed of classifier wheel on particle shape.  

Science.gov (United States)

Circularity, aspect ratio, modelx, and pellips were employed to study the effects of process parameters, namely varying feed loads and rotational speeds of the classifier wheel, of the fluidized bed opposed jet mill on the shape of the micronized particles produced. The Shapiro-Wilk statistical test showed that 80.0% of the shape distributions of the four descriptors were not normal. Therefore, the Kruskal-Wallis test, which is a nonparametric statistical test, was employed to analyze the data. Micronized particles were more spherical and less elongated, as indicated respectively by higher median circularity and lower median modelx values when compared to unmilled lactose. These descriptors were able to indicate that the particles had been micronized. When feed loads of 250 and 350 g were used, increasing the rotational speed of the classifier wheel was found to bring about a decrease in span values of all the shape descriptors, indicating that the micronized particles were more uniform in shape. Micronized particles produced had lower median aspect ratio values than the unmilled lactose, whereas a higher feed load of 450 g resulted in the production of micronized particles that were less uniform in shape and more elliptical in nature, as reflected by the lower median pellips values. A higher feed load of 450 g caused a high level of impingement of particles on to the rotating classifier wheel, causing decreased classifier wheel efficiency, and this resulted in a less well-controlled micronization process. Thus, aspect ratio and pellips were sensitive to the changes in performance of the classifier wheel. The four shape descriptors were proposed to be used collectively as indicators for the monitoring of the micronization process. PMID:12378963

Chan, L W; Lee, C C; Heng, P W S

2002-09-01

128

Improving energy efficiency of reheating furnace of sheet ingot plant and rolling mill Calibers of Gecamines / Lubumbashi by the recovery of waste heat of smoke  

International Nuclear Information System (INIS)

The economic management of energy is an important topic in industrial processes to the extent that it ensures the competitiveness of any firm and ensures its survival. Within this framework we plan to improve the energy efficiency of the powerful furnace for reheating lingots Rolling Mills and Cable Factory (of which the fuel is diesel) where we propose to install a head recovery exchanger between the hot fumes out of the oven (60 C) and combustion air taken initially at room temperature (250C). Without recovery the oven consumes on the average 101 liters of diesel per hour for its operation and yields a thermal efficiency of 68,6%. Whereas with recovery, it can reach a thermal efficiency of 86% on one of recoverers that we have proposed, and save up to 15,8 liters of diesel on its hourly consumption

129

Effects of grinding on certain crystalline structures  

International Nuclear Information System (INIS)

The effects of grinding on certain crystalline substances (ZnO, ZnS, Sb), have been studied using X-ray diffraction and electron microscopy. The treatments were carried out using a vibrating mill which involves a higher energy than more conventional equipment such as ball-mills. Various methods have been proposed for determining the width of the intrinsic profile (?). In the case of zinc oxide it has been shown possible to differentiate the respective contributions of the fragmentation effects and of lattice deformation effects to the overall effects of the grinding. For the two types of zinc sulfide (blend and Wurtzite) it has been shown that the blend-wurtzite) transition point is very much decreased, and that the rate of transformation of wurtzite into the stable form (blend) at room temperature is considerably increased by the grinding. In the case of antimony, the method of fragmentation shows the existence of an anisotropy which appears to be connected with easily cleavable planes. These observations show that in the case of grinding carried out with sufficient energy, the accumulation of this energy in the matter through the creation of lattice defects can accelerate the reaction rate or bring about physical transformations. (author)

130

Reduction of wheat middlings using a conventional and eight-roller milling systems  

Directory of Open Access Journals (Sweden)

Full Text Available Possibilities for the rationalization of the wheat flour milling process using the eightroller mill on the 1M and 2M passages of the reduction system have been investigated. At the same roll gaps and under the same sieving conditions, the lower flour yield has been obtained using an eight-roller mill compared to the conventional milling system (5-8 % followed by a higher energy requirements for grinding. By decreasing the roll gap setting and increasing the upper size limit of flour in the process with the eight-roller mill it is possible to increase flour yield and therefore decrease milling energy consumption per unit mass of flour produced without deterioration of flour quality as determined by ash content. With appropriate adjustments of the processing parameters in the eight-roller milling system it is possible to achieve similar milling results to those in the conventional system, while the overall investment, energy and maintenance costs are significantly lower.

Vukmirovi? ?uro M.

2009-01-01

131

Thermal characteristics of grinding fluids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

High Efficiency Deep Grinding (HEDG) combines high depths of cut, high grinding wheel speeds with high work piece feed rates to deliver a very high stock removal process that can produce components free of surface damage. High contact temperatures are a characteristic of the process and this produces a mass of hot grinding sparks being ejected from the grinding zone. Neat oil cutting fluids are typically used in HEDG due to their excellent lubricity, but the high grinding wh...

Massam, Mark

2008-01-01

132

Effects of concentration of dispersions on particle sizing during production of fine particles in wet grinding process  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Stirred media milling is a prospective technology for producing colloidal dispersions by means of wet grinding process. In the past, many researchers have studied the effects of different operating parameters such as size, shape, nature and quantity of grinding medium, the speed of agitator in grinding chamber, the feed rate of dispersions, etc. in stirred media mills. However, it is still less known how particle sizing which generates valuable information of particle size of the product to i...

Inam, Muhammad Asif; Ouattara, Soualo; Frances, Christine

2011-01-01

133

Application research of ferrous matrix composites in roller ring used in high-speed wire/bar rolling mill  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} A composite structure roller rings was fabricated by centrifugal casting. {yields} The roller rings consisted of outer WCP/Fe-C composites layer and inner Fe-C alloy matrix. {yields} Hardness attained to HRA80-85 in the composites layer, and HRA73-76 in inner Fe-C alloy matrix where the toughness was over 8 J/cm{sup 2}. {yields} The wear resistance of the roller rings excelled that of high-speed steel, and approached to that of the WC hard alloy roll. {yields} The production cost of the WCP/Fe-C composites roller ring decreased by 50%. - Abstract: Tungsten carbide particle (WC{sub P}) reinforced ferrous matrix composites roller rings were fabricated by centrifugal casting. The microstructures, properties and application effect of the composites roller rings were investigated by SEM, TEM and various property testers. The experimental results show that the WC{sub P} were uniformly distributed in outer reinforced-layer (working-layer) of 20-50 mm in thickness and their volume fraction reached 60-80 vol.%; there was a good interface bonding between WC{sub P} and Fe-C alloy without any reaction products; hardness attained to HRA80-85 in working-layer, and HRA73-76 in inner ferrous matrix where the toughness was over 8 J/cm{sup 2}; the wear resistance of the composites roller rings excels that of high-speed steel; service life of the composites parts approached to that of the WC hard alloy roll when the same WC{sub P}-volume-fraction in working-layer were obtained for both of them, but the production cost of the WC{sub P}/Fe-C composites roller ring decreased by 50%.

Song Yanpei, E-mail: sypei@mail.haust.edu.cn [School of Material Science and Engineering, Henan University of Science and Technology, No 48 Xiyuan Road, Luoyang 471003 (China); Li Xiuqing; Bi Shuangxu [School of Material Science and Engineering, Henan University of Science and Technology, No 48 Xiyuan Road, Luoyang 471003 (China)

2010-09-15

134

Application research of ferrous matrix composites in roller ring used in high-speed wire/bar rolling mill  

International Nuclear Information System (INIS)

Research highlights: ? A composite structure roller rings was fabricated by centrifugal casting. ? The roller rings consisted of outer WCP/Fe-C composites layer and inner Fe-C alloy matrix. ? Hardness attained to HRA80-85 in the composites layer, and HRA73-76 in inner Fe-C alloy matrix where the toughness was over 8 J/cm2. ? The wear resistance of the roller rings excelled that of high-speed steel, and approached to that of the WC hard alloy roll. ? The production cost of the WCP/Fe-C composites roller ring decreased by 50%. - Abstract: Tungsten carbide particle (WCP) reinforced ferrous matrix composites roller rings were fabricated by centrifugal casting. The microstructures, properties and application effect of the composites roller rings were investigated by SEM, TEM and various property testers. The experimental results show that the WCP were uniformly distributed in outer reinforced-layer (working-layer) of 20-50 mm in thickness and their volume fraction reached 60-80 vol.%; there was a good interface bonding between WCP and Fe-C alloy without any reaction products; hardness attained to HRA80-85 in working-layer, and HRA73-76 in inner ferrous matrix where the toughness was over 8 J/cm2; the wear resistance of the composites roller rings excels that of high-speed steel; service life of the composites parts approached to that of the WC hard alloy roll when the same WCP-volume-fraction in working-layer were obtained for both of them, but the production cost of the WCP/Fe-C composites roller ring decreased by 50%.

135

Rolling of rods of tungsten alloyed with lanthanum  

International Nuclear Information System (INIS)

Particularities of rolling process for rods of tungsten doped alloys and the design of test-commercial rolling mill of the MK-210 type are considered. The new process using rolling mills with four-roll passes permits to manufacture products with the uniformly developed structure and high surface quality. The yield of suitable products using a wire with 1.5-2.0 mm diameter produced of rolled billets is 15% higher than that of the mill one

136

Applications of High-Efficiency Abrasive Process with CBN Grinding Wheel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

High-efficiency abrasive process with CBN grinding wheel is one of the important techniques of advanced manufacture. Combined with raw and finishing machining, it can attain high material removal rate like turning, milling and planning. The difficult-to-grinding materials can also be ground by means of this method with high performance. In the present paper, development status and latest progresses on high-efficiency abrasive machining technologies with CBN grinding wheel relate to high speed...

Yan Zhou; Changhe Li; Yali Hou

2010-01-01

137

Assessment of air pollution and its effects on the health status of the workers in beam rolling mills factory (Iran National Steel Industrial Group from Ahvaz-Iran  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Air pollutants of iron- and steel-making operations have historically been an environmental and health hazard. These pollutants include gaseous substances such as sulfur oxide, nitrogen dioxide, and carbon monoxide. The Iran National Steel Industrial Group beam rolling mills factory has two production lines viz. line 630 and line 650, with different beam production capabilities and is capable of producing different types of beams. Materials and Methods: A retrospective cross-sectional study on 400 workers in different exposure levels to environmental pollution was performed during 2005 to determine the mean value of respirable particulate matter (RPM concentrations and its effects on the health status of workers. To elicit information regarding the health status of the worker, the National Institute for Occupational Safety and Health standard questionnaire was used. Fisher?s exact test was performed to assess the relative risk (RR of exposure to air pollution on cardiovascular diseases, chest tightness, cough, difficulty in retention, i.e. loss of memory, tension, occupational fatigue, and occupational stress in exposed workers. Results: There was significant difference in RPM pollution level between two product lines. The RR of exposure to air pollution on cardiovascular diseases, chest tightness, cough, difficulty in retention, i.e. loss of memory, tension, occupational fatigue, and occupational stress in exposed workers were 2.78, 2.44, 2.15, 1.92, 1.57, 3.90, and 2.09, respectively.

Rafiei Masoud

2009-01-01

138

Adsorption of single-strand alkylammonium salts on bentonite, surface properties of the modified clay and polymer nanocomposites formation by a two-roll mill  

International Nuclear Information System (INIS)

The adsorption of tallow alkylammonium salts onto bentonite from the Lopburi province in Thailand, and the effect of surface wettability on the formation of polymer-clay nanocomposites are reported. We looked specifically at octadecyltrimethyl ammonium chloride (S18), a popular member of the tallow alkylammonium salt family. The adsorption of S18 onto the bentonite interlayer can be divided into three distinct stages depending upon the initial concentration of S18. These stages are (a) monolayer formation, (b) intermediate state of double layer formation and (c) double layer formation. A decrease in surface energy driven by drops in the values of the polar and dispersive components was observed as the amount of surfactant surface coverage increased. Using thermal gravimetric analysis (TGA), the critical surface energy (CSE) of organoclay was found to decrease as the amount of absorbed S18 increased. S18 organoclay with different degrees of surface coverage was used in a two-roll mill to prepare high-density polyetheylene (HDPE)-clay nanocomposites. The oxidized polyethylene wax (OWax) was used as a dispersing agent to promote the delamination of the organoclay platelets. The results from X-ray diffraction (XRD) and transmission electron microscope (TEM) indicated a difference in the dispersing capability of the organoclay.

139

Study on anaerobic treatment of hazardous steel-mill waste rolling oil (SmWRO) for multi-benefit disposal route.  

Science.gov (United States)

Steel-mill waste rolling oil (SmWRO) is considered as hazardous substance with high treatment and disposal fees. Anaerobic process could not only transform the hazardous substance into activated sludge, but also generate valuable biogas. This study aimed at studying the biochemical methane potential of SmWRO under inoculum to substrate VS ratios (ISRs) of 0.25, 0.5, 1, 1.5, 2 and 3 using septic tank sludge as inoculum in mesophilic and thermophilic conditions, with blank tests for control. Specific biogas yield (mL/g VS(added)), net biogas yield (mL/g VS(removed)) and VS removal were analyzed. The ANOVA results indicated great influence of ISR and temperature on studied parameters. ISR of 1.5 at 55°C and ISR of 1.5 and 2 at 35°C were suggested with the highest specific biogas yield (262-265 and 303mL/g VS(added)). Kinetic analysis showed that Gompertz model fit the experimental data best with the least RMSE and largest R(2). PMID:24212130

Ma, Huanhuan; Li, Zifu; Yin, Fubin; Kao, William; Yin, Yi; Bai, Xiaofeng

2014-01-01

140

Centerless grinding of TiAl using conventional grinding wheels  

Energy Technology Data Exchange (ETDEWEB)

Ordered gamma titanium aluminide (TiAl) based alloys are now under consideration for automotive valves because of their light weight and high strength at temperatures up to 850 C. Finishing comprises as much as 70% of the cost of an automotive valve, therefore the grindability of TiAl valves will influence their commercial viability. This study compared the grindability of the TiAl alloy Ti-47Al-2Nb-1.75Cr (at%) to standard valve steels, nickel base superalloys, and conventional titanium alloys using the centerless grinding process. Three grinding conditions simulating stem grinding were selected. The power requirements, grinding time, and grinding wheel consumption were used to estimate the cost to grind TiAl on conventional centerless grinding equipment using vitrified bonded silicon carbide wheels. The metallurgical effects of rough and finish stem grinding cycles on the surface were determined. The grindability factor of TiAl, a measure of grinding cost, was slightly inferior to conventional valve steels, but much better than conventional titanium alloys. The high work hardening rate of the TiAl resulted in much better surface finish at high metal removal rates than that achieved in steels. No grinding cracks were observed, even under the rough grinding conditions. Microhardness profiles indicated significant work hardening of the surface under all three grinding conditions.

Jones, P.E.; Smits, D.; Eylon, D. [Univ. of Dayton, OH (United States); Smits, C. [Cincinnati Milacron Corp., OH (United States)

1995-12-31

 
 
 
 
141

Diretrizes para a construção de um moinho de bolas para a moagem de sólidos em laboratórios / Guidelines for the construction of a ball mill for grinding solids in the laboratory  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english In this paper, we show the construction of a low-cost, high-quality ball mill for obtaining finely divided powders, with the goal of presenting guidelines for achieving the best results for the milling process. This equipment allows for the adjustment of the size of the mill in order to process diff [...] erent quantities of material. The construction of mechanical and electrical components that provide increased efficiency, the choice of milling medium, and frequent problems experienced with homemade ball mills are discussed.

Lucas F. de, Paula; Alberth C., Alves; Heden C. S., Alves; Edimar A., Ribeiro; Ana G. B., Madurro; João M., Madurro.

142

A New Method of Manufacturing Small-Diameter Bars and Tubes from Hardly Deformable Steels in Skew Rolling  

Directory of Open Access Journals (Sweden)

Full Text Available The paper discusses the process of hot rolling on skew rolling mills and compares it with other methods of manufacturing rods (shape milling and tubes (pilger rolling. The method and results of calculation of the optimal price of a three-roll skew rolling mill taking into account the benefits for the purchaser and the manufacturer are given.

Ga?kin, A. M.

2007-01-01

143

Photoacoustic study of nanocrystalline silicon produced by mechanical grinding  

International Nuclear Information System (INIS)

Mechanical grinding (MG) was used to produce nanocrystalline silicon and its thermal and transport properties were investigated by photoacoustic absorption spectroscopy (PAS). The experimental results suggest that in as-milled nanocrystalline silicon for 10 h the heat transfer through the crystalline and interfacial components is similar, and after annealed at 470 oC the heat transfer is controlled by crystalline component.

144

Photoacoustic study of nanocrystalline silicon produced by mechanical grinding  

Energy Technology Data Exchange (ETDEWEB)

Mechanical grinding (MG) was used to produce nanocrystalline silicon and its thermal and transport properties were investigated by photoacoustic absorption spectroscopy (PAS). The experimental results suggest that in as-milled nanocrystalline silicon for 10 h the heat transfer through the crystalline and interfacial components is similar, and after annealed at 470 {sup o}C the heat transfer is controlled by crystalline component.

Poffo, C.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.b [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Souza, S.M.; Triches, D.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Grandi, T.A. [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Biasi, R.S. de [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

2011-04-01

145

Finite element analysis of deflection of rolls and its correction by providing camber on rolls  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rolling process is a key step in the production of flat steel products. Because of automation commonly implemented in flat product rolling mills, the products should meet the requirements of tight tolerances. one of the major defects observed in the rolling process is flatness and lack of attainment of the desired surface profile due to deflection of the rolls. The spatial shape and dimensions of the roll gap are influenced by the elastic deformation of all parts of the rolling stand equipmen...

Vijay Gautam

2013-01-01

146

Development of database and searching system for tool grinding  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: For achieving the goal of saving time on the tool grinding and design, an efficient method of developing the data management and searching system for the standard cutting tools is proposed in this study.Design/methodology/approach: At first the tool grinding software with open architecture was employed to design and plan grinding processes for seven types of tools. According to the characteristics of tools (e.g. types, diameter, radius and so on, 4802 tool data were established in the relational database. Then, the SQL syntax was utilized to write the searching algorithms, and the human machine interfaces of the searching system for the tool database were developed by C++ Builder.Findings: For grinding a square end mill with two-flute, a half of time on the tool design and the change of production line for grinding other types of tools can be saved by means of our system. More specifically, the efficiency in terms of the approach and retract time was improved up to 40%, and an improvement of approximately 10.6% in the overall machining time can be achieved.Research limitations/implications: In fact, the used tool database in this study only includes some specific tools such as the square end mill. The step drill, taper tools, and special tools can also be taken into account in the database for future research.Practical implications: The most commercial tool grinding software is the modular-based design and use tool shapes to construct the CAM interface. Some limitations on the tool design are undesirable for customers. On the contrary, employing not only the grinding processes to construct the grinding path of tools but the searching system combined with the grinding software, it gives more flexible for one to design new tools.Originality/value: A novel tool database and searching system is presented for tool grinding. Using this system can save time and provide more convenience on designing tools and grinding. In other words, the company productivity can be improved.

J.Y. Chen

2008-02-01

147

The influence of grinding oil viscosity on grinding heat and burn damage in creep-feed grinding{copyright}  

Energy Technology Data Exchange (ETDEWEB)

Grinding oils are widely used in precision grinding, such as tool grinding, thread grinding and gear grinding, during which processes grinding burn is the most prevalent damage affecting the integrity of ground surface. This paper discusses the influence of oil viscosity on grinding heat and burn damage in creep-feed-grinding. Experimental results indicated that, under lighter grinding conditions, the effects of oil viscosity was not observed, but under heavy grinding conditions grinding burn occurred when using low viscosity oil. When the viscosity of the oil was increased, grinding heat and burn damage tended to be reduced. As the viscosity was increased to a certain level, grinding burn reduction, by further increasing the viscosity, became less while other problems such as much higher oil pump noise and reduced oil flow occurred. It is clear that a viscosity limit exists for given grinding conditions. 5 refs., 4 figs., 3 tabs.

Zhen-Change Liu [Shandong Univ. of Technology, Jinan (China); Abe, Satoshi; Noda, Masahiro [Yushiro Chemical Industry Co. Ltd., Kanagawa (Japan)

1995-08-01

148

Microparticles prepared by grinding of polymeric films.  

Science.gov (United States)

Microparticles were prepared by a film grinding method, whereby thin drug-containing ethylcellulose films were cryogenically ground into microparticles. The particle size and shape of the microparticles could be controlled by the thickness of the films and by the milling time. The encapsulation efficiency as well as the in vitro drug release depended on the physical state of the drug in the ethylcellulose matrix (dispersed vs dissolved). Increased drug loadings and decreased particle size and film thickness increased the drug release. Microparticles prepared from cast films were more dense and had a slower drug release compared to microparticles prepared from sprayed films or from films prepared from an aqueous colloidal ethylcellulose dispersion, Aquacoat ECD. Lamination of the drug-containing film with a drug-free polymer layer on both sides resulted in a reduced drug release. Hydrophilic plasticizers acted as pore-formers and accelerated drug release, while lipophilic plasticizers reduced the drug release. The solubility of the drug in the organic polymer solution was one of the main parameters to achieve high encapsulation efficiencies and extended drug release, while dispersed drug was released much faster. The drug release from microparticles prepared by film grinding was faster than from microparticles prepared by the solvent evaporation method. The faster release was attributed to the fractured surface of the ground particles. Grinding of microparticles, which were prepared by the solvent evaporation, also resulted in a faster release. PMID:12909549

Elkharraz, K; Dashevsky, A; Bodmeier, R

2003-01-01

149

Applications of High-Efficiency Abrasive Process with CBN Grinding Wheel  

Directory of Open Access Journals (Sweden)

Full Text Available High-efficiency abrasive process with CBN grinding wheel is one of the important techniques of advanced manufacture. Combined with raw and finishing machining, it can attain high material removal rate like turning, milling and planning. The difficult-to-grinding materials can also be ground by means of this method with high performance. In the present paper, development status and latest progresses on high-efficiency abrasive machining technologies with CBN grinding wheel relate to high speed and super-high speed grinding, quick point-grinding, high efficiency deep-cut grinding, creep feed deep grinding, heavy-duty snagging and abrasive belt grinding were summarized. The efficiency and parameters range of these abrasive machining processes were compared. The key technologies of high efficiency abrasive machining, including grinding wheel, spindle and bearing, grinder, coolant supplying, installation and orientation of wheel and workpiece and safety defended, as well as intelligent monitor and NC grinding were investigated. It is concluded that high efficiency abrasive machining is a promising technology in the future.

Yan Zhou

2010-04-01

150

Surface Fine Grinding via a Regenerative Grinding Methodology  

Science.gov (United States)

This paper presents a regenerative surface fine grinding methodology to remove grinding defects of traditional operations and to improve the quality of surface flatness. All possible surface defects produced by traditional and creep-feed grinding operations are carefully reviewed and circumvented. These defects include non -uniform traces, pitting spots, scratches, burnouts, and quenching breakage. To alleviate these traditional grinding defects, the paper presents a new approach by designing and constructing a regenerative surface fine grinding system that includes a mechanism that carries the submerged workpart in an oil-contained open box. The fine grinding tool held by the spindle-chuck unit of the CNC machine is moved in relative to the workpart surfaces by a combined trajectory of a cycloid path, a linear feed and a lateral travel. Some numerical simulations for selecting appropriate grinding trajectories are presented and simulated. The trajectory is selected based upon the resulting quality of contact uniformity and homogeneity as expressed in terms of contact frequency to each point on the workpart surface. The simulation model is then used to characterize appropriate working range of each grinding parameter. Different grinding paths are thus generated and superposed. A working machine is designed and built based upon the simulation results. Several experiments are carried out on the constructed grinding system with the grinding tool mounted to the spindle-chuck unit of the CNC machine. The surface quality of the ground workpart is measured. Tests on different system parameters demonstrate the importance of choosing the correct grinding wheel and grit size and an illustration of the proper selection of process and system parameters are presented. The experimental results are compared with those of analytical solutions. Good agreement between them is observed. In ninety minutes fine-grinding operations using the proposed method, the workpart surfaces generally possess no damage and surface roughness is reduced to the range of 0.02~0.04?m in Ra. To verify the effectiveness of the proposed method, the results of fine grinding operations using various process parameters are measured and recorded. The effects of various combinations of process parameters including trajectory density, uniformity and grinding efficiency on the effect of surface flatness enhancement are carefully examined and concluded.

Lai, Hsin-Yi; Chen, Chao'-Kuang

2006-10-01

151

GRINDING OF MEDICAL IMPLANTS IN COBALT-CHROMIUM ALLOY  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The manufacturing of medical implants such as knees or ankles prostheses require surface roughness that milling operations cannot achieve. Thus, polishing operations are mandatory but these operations are mainly carried out manually by skilled workers. As this process is expensive in terms of price and downtime of the parts, automatic finishing on machine tools is an alternate solution to improve quality and productivity. Thus, the aim of this paper is to study the performance of a grinding (...

Tournier, Christophe; Christophe, Iabassene; Anthony, Guiot; Quinsat, Yann

2012-01-01

152

Powder homogenization using a hammer mill.  

Science.gov (United States)

Hammer mill applicability in the comixing milling operation is discussed with reference to a 1:1000 microfine salicylic acid-sucrose binary system. The hammer mill would not serve as a mixing machine under most circumstances because of the low holdup capacity. Grinding of pure materials was preferable to mixture grinding since active ingredients could be lost during the milling operation. Remixing was always necessary following comminution of the mixture in the hammer mill. Grinding followed by remixing considerably enhanced mixture homogeneity. A large size range was produced by comminution, which resulted in the segregation of ordered units such that the final mixture could be described as a randomized ordered mixture. PMID:458572

Yeung, C C; Hersey, J A

1979-06-01

153

Vibration-Assisted Grinding with a Newly Developed Rotary Mechanism using Induction Motor  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the analysis of mechanisms of removal in vibration-assisted grinding process. It is known that generally for machining, application of vibration helps to increase material removal rate, reduces tool wear rate and increases depth of machining. As the failure of a component originates from the surface, effect of assisted grinding is carried out on a milling machine. The machine is equipped with a grinding wheel on which small frequency vibrations are applied. The resultant path of the tool is analytically evaluated. Longitudinal vibrations are developed by using a rotary mechanism. It was demonstrated that there are several favorable effects of vibrations in grinding process including: reduced tool forces, better surface finish and improved tool life. It is observed that the application of vibrations improve the process characteristics in grinding, to a large extent.

Noel Williamson*1

2014-04-01

154

Study on Spindle System Static and Dynamic Characteristic in Grinding Head Based on Finite Element Analysis  

Directory of Open Access Journals (Sweden)

Full Text Available With the spindle system of M8400A type roll grinding machine as the object of the research. On the basis of the establishment of the three-dimensional solid model of the roll grinder grinding head spindle system, carry out finite element static analysis, with the spindle structural stress and strain diagram, study its static characteristics, carry out modal analysis in the properly simplified spindle system with the finite element method, analyze the calculated natural frequency value, study dynamic characteristics of the spindle system, lay the foundation for the realization of the dynamic design of product.

Jin-Ling Cao

2013-01-01

155

Large-scale Evaluation of Nickel Aluminide Rolls in a Heat-Treat Furnace at Bethelehem Steel's (Now ISG) Burns Harbor Plate Mill  

Energy Technology Data Exchange (ETDEWEB)

At Bethlehem Steel Burns Harbor Plate Division (now ISG Burns Harbor Plate Inc.)'s annealing furnace, new nickel aluminide intermetallic alloy rolls provide greater high-temperature strength and wear resistance compared to the conventional H series cast austenitic alloys currently used in the industry. Oak Ridge National Laboratory and Bethlehem (ISG) partnered under a U.S. Department of Energy, Office of Industrial Technology's Emerging Technology Deployment Program to demonstrate and evaluate the nickel aluminide intermetallic alloy rolls as part of an updated energy efficient large commercial annealing furnace system. Many challenges were involved in this project, including developing welding procedures for joining nickel aluminide intermetallic alloys with H-series austenitic alloys, developing commercial cast roll manufacturing specifications, working with several commercial suppliers to produce a quantity of high quality, reproducible nickel aluminide rolls for a large steel industrial annealing furnace, installing and demonstrating the capability of the rolls in this furnace, performing processing trials to evaluate the benefits of new equipment and processes, and documenting the findings. Updated furnace equipment including twenty-five new automated furnace control dampers have been installed replacing older design, less effective units. These dampers, along with upgraded flame-safety control equipment and new AC motors and roll-speed control equipment, are providing improved furnace control and additional energy efficiency. Energy data shows up to a 34% energy reduction from baseline after the installation of upgraded furnace damper controls along with up to a 34% reduction in greenhouse gases, potential for an additional 3 to 6% energy reduction per campaign of light-up and shutdown, and a 46% energy reduction from baseline for limited trials of a combination of improved damper control and straight-through plate processing. The straight-through processing is now possible because of the nickel aluminide rolls which also provided plate product surface quality improvement that will allow the additional processing of surface critical material. Benefits also include associated large reductions in maintenance, reduction in spare rolls and associated component costs, and potential for greater through-put and productivity. Estimated project fuel cost reductions alone for processing 100,000 tons/yr through this furnace are almost $0.5 million/yr with the new dampers, and more than $600,000/yr with straight-through processing and new damper control, assuming natural gas prices of $6.00/MMBtu. The nickel aluminide rolls are competitively priced with conventional H series alloy rolls.

Mengel, J.

2003-12-16

156

Pilot-industrial technology of sintered tungsten bar section rolling  

International Nuclear Information System (INIS)

Results of development and industrial introduction of new technology for rolling of bar sections from sintered tungsten on specialized rolling mill MK-380 with four-high passes of the Chelyabinsk Polytechnical Institute design are given. The rolling mill design is described and recommendations are given as to the working roll materials. The new technology is characterized by a higher output and quality of produced sections in comparison with existing methods of processing

157

Rolling Stonesi kinokontsert kannab toorest rokiväge / Maris Meiessaar  

Index Scriptorium Estoniae

Martin Scorsese muusikalisest dokumentaalfilmist "Shine a Light - Valgus peale" (USA-Suurbritannia, 2008), mille keskmes on 2006. a. New Yorgi Beaconi teatris toimunud briti ansambli Rolling Stones kontsert

Meiessaar, Maris

2009-01-01

158

Design of the Soymilk Mill based on TRIZ Theory  

Directory of Open Access Journals (Sweden)

Full Text Available The soymilk mill is an important food machine, but its volume is too large to be suitable for house using. This study first analyzes some problems in the soymilk mill miniaturization. For these problems, the thinking tools, evolutionary tools and contradiction solving tool of TRIZ theory are used to resolve the conflict in the integration of grinding and boiling and in the keep grinding effect, to tackle the optimization problem in the grinding stria structure and mill plate speed, then the Dwarfs method and substance-field analysis model is used in solving the interference and the conditions water supply problems which are encountered in the design of the global structure and a micro soymilk mill is designed. Finally, the mechanical analysis model about soy granules, soymilk particles in the grinding zone and the computational model of motor starting torque are obtained; they provide the reference data for application of soymilk mill.

Jiang Fan

2013-05-01

159

Aspects in grinding of ceramics  

International Nuclear Information System (INIS)

Aspects in the grinding of ceramics have been investigated. Si3N4, ZrO2, SiC, and Al2O3 were ground with resin-bonded diamond wheels of grit numbers ranging from 80 to 800. Microstructural observations of ground surfaces show that grinding occurs predominantly by flow mode in Si3N4 and ZrO2, and by fracture and grain pullout in SiC and Al2O3. The measurement of grinding force shows that grinding resistances in Si3N4 and ZrO2 are significantly larger than those in SiC and Al2O3. As the grit number of the grinding wheel increases, maximum surface roughness significantly decreases in Si3N4, ZrO2, and SiC, but it apparently does not change in Al2O3. This unexpected result in Al2O3 is discussed in terms of the observed grinding mode and microstructure

160

Work during screw rolling  

Science.gov (United States)

A new technique is proposed to determine the specific volume work of deformation during screw rolling. Methods for determining the work of deformation in various sections of the deformation zone in a piercing mill are considered. The dependence of the work of deformation on the reduction in the deformation zone is obtained. A new approach is proposed to calculate the fracture sensitivity and the working of the structure of continuously cast round billets. The effect of the reduction ratio on the work of deformation in similar piercing mills located at OAO Pervoural'sk Nonvotrubnyi Plant and the Yuzhnotrubnyi Plant is estimated.

Golubchik, R. M.; Merkulov, D. V.; Klempert, E. D.; Medvedev, E. K.; Shelest, A. E.

2011-05-01

 
 
 
 
161

Compliant meso-scale grinding of silicon  

Science.gov (United States)

In this research, the need to create complex three-dimensional free-form shapes in silicon wafers for MEMS applications has been identified. Meso-scale grinding was chosen to perform the three-dimensional machining of silicon, among several other machining methods. Traditionally, ultra-rigid ultra-precision machines are used to machine silicon wafers in order to achieve ductile material removal mode to minimize grinding induced surface and subsurface defects. In this research, however, a compliant grinding methodology has been proposed to realize ductile regime material removal and to reduce grinding induced subsurface defects. A compliant meso-scale grinding apparatus, equipped with computer-controlled 3-axis movement, backlash-free flexure feeding and force monitoring, was developed to perform compliant silicon grinding experiments. Contour grinding, traverse grinding and plunge grinding experiments were carried out on the compliant grinding apparatus. These grinding experiments demonstrate that compliant grinding is capable of achieving good form accuracy and mirror surface finish. Further studies on grinding ductility, grinding induced subsurface defects indicate that compliant grinding can increase silicon ductility by 240.7%, reduce subsurface defects by 55.7% when compared with rigid grinding experiments. Based on off-line force analysis both in time domain and frequency domain, a first-cut detection algorithm was developed to detect wheel/workpiece contact in real-time. The algorithm is capable of adjusting to different motor vibrations and environmental noise levels by self-learning. The first-cut detection algorithm was tested successfully in real-time. To further improve form accuracy obtained on the compliant grinding apparatus, a normal grinding force model and a depth of cut model were developed to account for the large compliance in the grinding system. Numerical simulation was performed to predict actual depths of cut and the results were within 6% of the measured/actual depths.

Jiang, Bo

162

Adaptation of an Asperity Ploughing Model to Measured Roll Topographies  

Science.gov (United States)

A previously published asperity ploughing model has been adapted in order to approximate the measured as-ground roll surface topography. The model is then integrated with classical cold rolling plastic deformation equations including coupling to the lubricant film evolution through the roll bite. The friction distribution through the roll bite is thus a function of the specific details of the roll surface topography as well as the process parameters. predictions of roll force, torque and forward slip as well as sliding distance and volume of metal swept out by the asperities are then made and compared to experimental measurements for an aluminum alloy rolled on a laboratory rolling mill.

Lalli, L. A.; Malkani, H. G.; Sheu, S.

2004-06-01

163

Empirical estimation of grinding specific forces and energy based on a modified werner grinding model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Advanced grinding processes include relatively new grinding processes such as Creep Feed, HEDG and VIPER grinding. These processes are more productive than conventional grinding ones as a result of favourable process kinematics. Proper understanding of grinding forces can be useful in designing grinding machine tools and fixtures. Additionally information on specific energy helps in selecting process parameters for achieving optimum output. In the present paper, analysis of the effects of pro...

Mishra, Vijay Kumar; Salonitis, Konstantinos

2013-01-01

164

Spray rolling aluminum alloy strip  

Energy Technology Data Exchange (ETDEWEB)

Spray rolling combines spray forming with twin-roll casting to process metal flat products. It consists of atomizing molten metal with a high velocity inert gas, cooling the resultant droplets in flight and directing the spray between mill rolls. In-flight convection heat transfer from atomized droplets teams with conductive cooling at the rolls to rapidly remove the alloy's latent heat. Hot deformation of the semi-solid material in the rolls results in fully consolidated, rapidly solidified product. While similar in some ways to twin-roll casting, spray rolling has the advantage of being able to process alloys with broad freezing ranges at high production rates. This paper describes the process and summarizes microstructure and tensile properties of spray-rolled 2124 and 7050 aluminum alloy strips. A Lagrangian/Eulerian poly-dispersed spray flight and deposition model is described that provides some insight into the development of the spray rolling process. This spray model follows droplets during flight toward the rolls, through impact and spreading, and includes oxide film formation and breakup when relevant.

McHugh, Kevin M.; Delplanque, J.-P.; Johnson, S.B.; Lavernia, E.J.; Zhou, Y.; Lin, Y

2004-10-10

165

TRISO-coated spent fuel processing using a Grind-Leach head-end  

International Nuclear Information System (INIS)

Processing of TRISO-coated HTGR fuels with the grind-leach process requires that the fuel be finely pulverized for efficient and effective acid dissolution of the fuel components. Mechanical size reduction of the fuel is being investigated with jet mill technology as the final milling step. Laboratory experiments were performed with surrogates of crushed fuel compacts that indicate that milling to very small particle sizes is feasible. The size distribution of the milled product is sensitive to the solids feed rate, and the distribution may be bimodal which could support an effective solid-solid separation. (author)

166

Recent trends for rolling equipment  

Energy Technology Data Exchange (ETDEWEB)

Facility investments in the steel industry have increased considerably in the last two to three years. This is especially true for equipment related to the so-called high added-value steels'' such as rolling mills for automotive strip, surface treatment lines, continuous annealing lines, continuous pickling lines, et al. New technologies developed for these equipment have done much to accelerate trends toward higher quality, higher efficiency, increased automation, and increased yield. These new technologies include; application of mills to materials for the electronic industry, to annealing and galvanizing process lines for automotive sheets; fully continuous cold rolling mills; old mills rebuilt to state-of-the-art specifications; new process line technology, including a way to obtain a consistent coating thickness on hot-dip galvanizing lines, special bearings for rolls submerged in zinc pots, and a new scale removal device; moreover, AC variable-speed devices; advanced controllers; automation of peripherals; and automation of sample preparation and testing. These important new trends in rolling mill equipment technology are outlined with the definite name of equipment. 3 refs., 2 figs., 3 tabs.

Fujino, N.; Sugiyama, T.; Shimizu, I. (Hitachi, Ltd., Tokyo (Japan))

1990-08-01

167

Quality Improvement in the Production Process of Grinding Balls.  

Directory of Open Access Journals (Sweden)

Full Text Available The paper outlines how experiments were carried out to determine the optimum chromium/carbon (Cr/C ratio that brings the required hardness of 65HRC and to establish a quenching technique for the grinding balls. Matlab was also used to develop a mathematical model for the ball wear rate and its cost effectiveness basing on surface theory and volume theory. From the experimental results, the Cr/C ratio in the chemical composition 18:2 gave the required hardness. Also water quenched grinding balls gave the required hardness. The mathematical model was validated for both volume and surface theories using correlations of coefficients. The correlations of coefficients for both volume and surface theorems were 0.9994 and 0.9985 respectively and are all close to unity, which shows that both theories provide good descriptions of the way in which the masses of the balls decrease as a function of the amount of material milled.

Andrew Muzinda

2013-09-01

168

Effect of TiC and TaC powder grinding on their structure  

International Nuclear Information System (INIS)

TiCsub(0.96) and TaCsub(0.98) carbides were subjects of investigation. Powders were grinded in a ball vibrating mill in ethanol under normal conditions during 3 h. Average size of particles was determined from anti Lsub(L) frequency and anti Lsub(V) volume distributions. It was shown that to characterise powder polydispersion, the distribution of particle size in anti Lsub(V) volume, and not in frequency, should be used; mean value of anti Lsub(V) reflects more completely the change of particle size of TiC and TaC during grinding. The deformation process during grinding depends on the aggregation degree of powder particles. Fine-structural properties of fine and coarse fractions of grinded material differ significantly

169

Bruxism (Teeth Grinding or Clenching) (For Parents)  

Science.gov (United States)

... Bruxism Last? Childhood bruxism is usually outgrown by adolescence. Most kids stop grinding when they lose their ... a few kids do continue to grind into adolescence. And if the bruxism is caused by stress, ...

170

Efficient Fuel Pretreatment: Simultaneous Torrefaction and Grinding of Biomass  

DEFF Research Database (Denmark)

Combining torrefaction and grinding of biomass in one reactor may be an attractive fuel pretreatment process. A combined laboratory torrefaction and ball mill reactor has been constructed for studies of the influence of temperature and residence time on the product yields and particle size reductions of Danish wheat straw, spruce chips, and pine chips. On the basis of initial experiments, which evaluated the influence of reactor mass loading, gas flow, and grinding ball size and material, a standard experimental procedure was developed. The particle size reduction capability of the torrefaction process has been evaluated by the relative change in d50, and this method was compared to the Hardgrove grindability index (HGI), showing reasonably similar results. Significant differences in torrefaction behavior have been observed for straw and spruce chips torrefied at 270–330 °C. Torrefaction of straw for 90 min yielded a higher mass loss (27–60 wt %) and relative size reduction (59–95%) compared with spruce (massloss of 10–56 wt % and size reduction of 20–60%). The two types of biomass investigated differ with respect to hemicellulose type, lignocellulosic composition, particle morphology, and ash composition, where straw has a higher alkali content. This and other studies indicate that the large difference in the alkali contents of the biomasses is the main cause for the observed difference in torrefaction characteristics. Experiments with separate particle heating and grinding showed a swift grinding of the torrefied biomass. This implies that the rate-limiting step in the laboratory reactor is the heat transfer and not the grinding process. Large pine particles (8–16 mm) showed a slightly higher mass loss than 4–8 and <4 mm particles. This could be the consequence of exothermic reactions in the particle core, which locally increase the temperature and conversion.

Saleh, Suriyati Binti; Hansen, Brian Brun

2013-01-01

171

Thermal aspects of grinding for surface integrity  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thermal aspects of grinding are analyzed in detail since it is argued that temperature controls the effect of grinding on workpiece surface integrity. Transient and steady state heat partition in sliding contact is discussed in detail. This leads to a complete thermal model for heat partition and temperatures in surface grinding. Numerical predictions of the model are shown to agree with experimental results available in the literature. Effects of grinding conditions including real contact ar...

Ju, Yongqing

1997-01-01

172

Automatic programming of grinding robot  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new programming method is developed for grinding robots. Instead of using the conventional jog-and-teach method, the workpiecc geometry is automatically scanned by a contour tracking system. During tracking of the workpiece contour, the robot position is continuously logged. Finally a robot program is automatically generated.

Trygve Thomessen; Elle, Ole J.; Jon Lund Larsen; Torgrim Andersen; Pedersen, Jahn E.; Lien, Terje K.

1993-01-01

173

Automatic programming of grinding robot  

Directory of Open Access Journals (Sweden)

Full Text Available A new programming method is developed for grinding robots. Instead of using the conventional jog-and-teach method, the workpiecc geometry is automatically scanned by a contour tracking system. During tracking of the workpiece contour, the robot position is continuously logged. Finally a robot program is automatically generated.

Trygve Thomessen

1993-04-01

174

Ceramic-bonded abrasive grinding tools  

Science.gov (United States)

Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

Holcombe, Jr., Cressie E. (Farragut, TN); Gorin, Andrew H. (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN)

1994-01-01

175

Ceramic-bonded abrasive grinding tools  

Science.gov (United States)

Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

Holcombe, C.E. Jr.; Gorin, A.H.; Seals, R.D.

1994-11-22

176

Fused silica fine grinding with low roughness  

Science.gov (United States)

Lithography-optics is one of the most complex optical systems. The fine grinding process is the most important step before polishing. Roughness and sub-surface damage (SSD) are essential outputs of fine grinding. We demonstrate the method that use fix abrasive cup tool with CNC grinding machine to complete the fine grinding process, even instead of lapping process. And experiment sample roughness can reach 23.40nm rms and Ra 18.554nm. The SSD estimate is about 2 ?m which is also smaller than commercial lapping process. The fine grinding output can satisfy the lithography optic fabrication demands and efficiently reduce the polishing time.

Dai, Lei; Gu, Yongqiang; Wu, Di

2014-08-01

177

Statistical Approach Optimizing Slant Feed Grinding  

Science.gov (United States)

Micro-grinding is one of the methods to create submillimeter-structures, and it has been applied to many processes such as finishing of internal surface of fuel injector valves and dental technique. Micro-grinding has recently been required to improve ground surface roughness. Slant feed grinding is a machining method to improve finished surfaces, but the mechanism of improving ground surface roughness of slant feed grinding has not been completely clarified yet. This paper proposed a theoretical method for calculating ground surface roughness of slant feed grinding by using a statistical approach. This method can clarify the mechanism, and it can also optimize conditions of slant feed grinding. A self-developed micro-grinding device was then employed to confirm the calculation method experimentally, and the experimental results agreed with the theoretical calculation.

Shimada, Keita; Liew, Pay Jun; Zhou, Tianfeng; Yan, Jiwang; Kuriyagawa, Tsunemoto

178

Prediction of work-roll temperature distribution in continuous hot strip rolling process  

International Nuclear Information System (INIS)

Prediction of temperature distribution within the work-rolls during the hot slab rolling process is of great importance to mill designers. This is because, not only the temperature distribution in rolling material and the dimensional accuracy are depended on work-roll temperature but also the roll life is a function of its temperature distribution. In this paper using the heat transfer equations for moving media and a two dimensional finite element method, the work-roll temperature distribution during continuous hot strip rolling process is predicted. To achieve an accurate temperature field the effects of various factors including the rolling speed, interface heat transfer coefficient, and the amount of slab thickness reduction at each deformation pass are taken into account. Comparison between the predicted and experimental published results depicts the validity of the mathematical model. (author)

179

Simulation analysis of grinding wheel motion trajectory on SiC ceramics aspheric surface grinding  

Science.gov (United States)

In grinding process of SiC ceramics aspheric surface, the motion trajectory of grinding wheel has great influence on the surface forming. The paper provides mathematical models of grinding wheel movements; analytical simulation was done to describe the trajectories of the grinding wheel in manufacturing an aspherical workpiece. The effect of grinding parameters (including the rotation speed of the workpiece, the feed rate of grinding wheel etc.) on the aspheric surface coverage rate was conducted and discussed in detail. An experimental study was done according to the simulation results and an aspheric surface with form error less than 10?m was gained.

Zhang, Feihu; Liu, Lifei; Li, Chunhui

2014-08-01

180

Enhanced dissolution and bioavailability of raloxifene hydrochloride by co-grinding with different superdisintegrants.  

Science.gov (United States)

The present study investigated the effect of co-grinding raloxifene HCL (RHCL) with different superdisintegrants, namely crospovidone (CP), croscarmellose sodium (CCS) and sodium starch glycolate (SSG), using a ball mill, in order to determine the potential effect on dissolution rate and bioavailability of raloxifene hydrochloride (RHCL). The dissolution studies of the co-ground compositions and the corresponding physical mixtures were carried out in U.S. Pharmacopeia (USP) Type II apparatus. The solid state interactions of the co-ground and the physical mixtures were evaluated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The pharmacokinetics of co-ground mixture (1 : 5 RHCL : CP) and milled RHCL was evaluated following oral administration (25 mg/kg) in healthy female Sprague-Dawley rats. DSC studies showed that the crystalline nature of RHCL was reduced after co-grinding with superdisintegrants, while co-grinding with CP resulted in significant particle-size reduction of the mixture. Significant enhancement in dissolution rate was observed with co-ground mixture of RHCL with CP (1 : 5). The extent of the mean plasma exposures of RHCL was 7-fold higher in animals treated with co-ground mixture of RHCL, CP (1 : 5) compared to animals treated with milled RHCL. Co-grinding of RHCL with CP, reduced drug crystallinity, increased the rate and extent of dissolution, and improved bioavailability. PMID:20190431

Jagadish, Balasubramaniam; Yelchuri, Rajesh; K, Bindu; Tangi, Hemalatha; Maroju, Swetha; Rao, Vinay Umesh

2010-03-01

 
 
 
 
181

Spray Rolling Aluminum Strip for Transportation Applications  

Energy Technology Data Exchange (ETDEWEB)

Spray rolling is a novel strip casting technology in which molten aluminum alloy is atomized and deposited into the roll gap of mill rolls to produce aluminum strip. A combined experimental/modeling approach has been followed in developing this technology with active participation from industry. The feasibility of this technology has been demonstrated at the laboratory scale and it is currently being scaled-up. This paper provides an overview of the process and compares the microstructure and properties of spray-rolled 2124 aluminum alloy with commercial ingot-processed material

Kevin M. McHugh; Y. Lin; Y. Zhou; E. J. Lavernia; J.-P. Delplanque; S. B. Johnson

2005-02-01

182

Radiometric study of creep in ingot rolling  

International Nuclear Information System (INIS)

The radiometric study of creep during ingot rolling performed in the rolling mill of the Vitkovice Iron and Steel Works and the first results are described. Selected sites in 3 to 8 ton ingots were labelled with 2 to 3.7x105 Bq of 60Co and after rolling into blocks, the transposition of the labelled sites of the ingots was investigated. The results indicate creep during rolling, local extension in certain sites under study and help to determine the inevitable bottom crop incurred in the forming. Finally, the requirements put on the radiometric apparatus for the next stages of technological research are presented. (author)

183

The method of assessment of the grinding wheel cutting ability in the plunge grinding  

Science.gov (United States)

This article presents the method of comparative assessment of the grinding wheel cutting ability in the plunge grinding kinematics. A new method has been developed to facilitate multicriterial assessment of the working conditions of the abrasive grains and the bond bridges, as well as the wear mechanisms of the GWAS, which occur during the grinding process, with simultaneous limitation of the workshop tests range. The work hereby describes the methodology of assessment of the grinding wheel cutting ability in a short grinding test that lasts for 3 seconds, for example, with a specially shaped grinding wheel, in plunge grinding. The grinding wheel macrogeometry modification applied in the developed method consists in forming a cone or a few zones of various diameters on its surface in the dressing cut. It presents an exemplary application of two variants of the method in the internal cylindrical plunge grinding, in 100Cr6 steel. Grinding wheels with microcrystalline corundum grains and ceramic bond underwent assessment. Analysis of the registered machining results showed greater efficacy of the method of cutting using a grinding wheel with zones of various diameters. The method allows for comparative tests upon different grinding wheels, with various grinding parameters and different machined materials.

Nadolny, Krzysztof

2012-09-01

184

Tallinnas on kõne all spordi muutuv roll kõrghariduses / Raivo Russmann, Malle Jürves  

Index Scriptorium Estoniae

Tallinna Tehnikakõrgkooli korraldusel toimub 8.-12. novembrini Tallinnas 9. üle-euroopalise kõrgkoolide spordikeskuste assotsiatsiooni ENAS konverents, mille teemaks on spordi muutuv roll kõrghariduses

Russmann, Raivo

2006-01-01

185

Nano-structured powders of magnesium hydride prepared by a controlled reactive grinding process  

International Nuclear Information System (INIS)

This work deals with the synthesis of magnesium hydride MgH2 by a reactive grinding of metallic magnesium under hydrogen atmosphere. A vibrating grinding mill has been used in which only one ball makes a regular vertical movement. In these conditions, the final state only depends of a limited number of parameters. After grinding, the powders microstructure has been studied by X-ray diffraction, scanning and transmission electron microscopies, electronic microprobe and their performances have been determined by thermal gravimetric analysis. In the optimal conditions, have been obtained nano-structured powders of magnesium hydride presenting storage capacities per unit of mass of 7%, value which is very near the theoretical capacity. (O.M.)

186

Influence of the charge properties on the milling tools wear during intensive milling in liquid environment  

Directory of Open Access Journals (Sweden)

Full Text Available Grinding belongs to the basic technological operations in the treatment and processing of minerals. The method of the intensive grinding in a liquid environment has become attractive for the preparation of technologically advanced materials of the high fineness. Its choice was motivated by the intensification of dispersion and by the protection of ground powder against oxidation. The result of energy and material interactions among the grinding media and grinding environment is the wear of the grinding media and contamination of the ground material. The hardness of the particles has an important influence on the rate of wear. Particles with hardness lower than that of the surface of milling tools cause much less wear than harder particles. The wear rate becomes much more sensitive to the ratio of the abrasive hardness Ha to the surface hardness Hs when Ha/Hs <¡­1.The paper deals with the influence of four minerals with various microhardness (corundum, quartz, silicon and magnesite on the steel milling tools wear during intensive milling.. Experiments were performed in a vibration mill in methanol under same conditions. The grinding time was changed in a geometric sequence from 0,125 to 4 hours. The newly created surface area providesa basic information on grinding. The specific surface area was determined by the standard Brunauer-Emmett-Teller (BET method using the appratus Gemini 2360 (Sylab, Austria. The concentration of iron was determined by AAS (SpectrAA-30, Varian, Australia. It was confirmed that the rate of ball wear depends on the hardness of feed materials. It was found that the relation between the contamination of the ground powders by wear and the specific surface area increment is linear and the slope depends on the microhardness of the ground material.

Števulová Nadežda

2002-06-01

187

Mill’s Perfectionism  

Directory of Open Access Journals (Sweden)

Full Text Available J. S. Mill lays great emphasis on the importance of the notion of theindividual as a progressive being. The idea that we need to conceive the self as an object of cultivation and perfection runs through Mill’s writings on various topics, and has played a certain role in recent interpretations. In this paper I propose a specific interpretation of Mill’s understanding of the self, along the lines of what Stanley Cavell identifies as a “perfectionist” concern for the self. Various texts by Mill, ranging from the Logic to On Liberty, show an understanding of the self in which both the theoretical and the practical domain are presented as being internally connected to the transformation of the self. Mill elaborates a criticism of a notion of truth articulated by doctrines having a life independent of the self, as well as a notion of choice which is not the expression of one’s inner self. This internal relation of truth and choice to the self generates a special dialectic within the self, which Mill explores in On Liberty’s second and third chapters by means of several contrasts, such as passive vs. active knowledge, living vs. dead beliefs, or being oneself vs. liking and choosing in crowds.

PIERGIORGIO DONATELLI

2006-12-01

188

The decrease of energy consumption in the cement grinding process. Zmniejszenie zuzycia energii w procesie mielenia cementow portlandzkich  

Energy Technology Data Exchange (ETDEWEB)

The intensification of the grinding process is described by the use of surface-active substances in the cement mills. As surface-active substances ethylene glycol, propylene glycol and poly glycols have been used. It has been proved that the addition of 0,02-0,025% of the above substances results in the increase of cement mill rate by about 20%. (author). 15 refs., 3 figs., 2 tabs.

Klecan, R. (Instytut Materialow Ogniotrwalych, Gliwice (Poland))

1994-03-01

189

Manufacturing processes 2 grinding, honing, lapping  

CERN Document Server

Presents a view of the most common machining and non-machining manufacturing processes. This volume describes the characteristics of abrasive tools, their design and manufacturing, followed by the fundamentals of grinding fluids. It also discusses grinding of different materials (steel, cast iron, hard and brittle materials, nickel and titanium).

Klocke, Fritz

2009-01-01

190

Theoretical considerations of machining with grinding wheels  

Directory of Open Access Journals (Sweden)

Full Text Available Grinding is one of the most versatile methods of removing material from machine parts by the cutting action of the countless hard and sharp abrasive particles of a revolving grinding wheel. It works by forcing the abrasive grains into the surface of the workpiece so that each grain cuts away a small bit of material in the form of chips. Abrasive grinding wheel is an expendable wheel that carries an abrasive compound on its periphery. They are made of small, sharp and very hard natural or synthetic abrasive minerals, bonded together in a matrix to form a wheel. The paper presents a review of some of the characteristics as well as theoretical considerations of operations of abrasive grinding wheel. The relationships among the various grinding parameters; the radial force f, the force on individual grit of grinding wheel F, velocity of grinding wheelg Vg, velocity of work piecew Vw, the wheel diameterg Dg, and the diameter of the work piece Dw were established for given grinding operations.

Andrew Oyakhobo Odior

2013-03-01

191

Precision diamond grinding of ceramics and glass  

Energy Technology Data Exchange (ETDEWEB)

A new research initiative will be undertaken to investigate the effect of machine parameters and material properties on precision diamond grinding of ceramics and glass. The critical grinding depth to initiate the plastic flow-to-brittle fracture regime will be directly measured using plunge-grind tests. This information will be correlated with machine parameters such as wheel bonding and diamond grain size. Multiaxis grinding tests will then be made to provide data more closely coupled with production technology. One important aspect of the material property studies involves measuring fracture toughness at the very short crack sizes commensurate with grinding damage. Short crack toughness value`s can be much less than the long-crack toughness values measured in conventional fracture tests.

Smith, S.; Paul, H.; Scattergood, R.O.

1988-12-01

192

Diamond-Bronze Coatings for Grinding Applications  

Science.gov (United States)

Grinding applications for the machining of stone and concrete require composite tools where large diamonds are perfectly embedded into a metallic matrix. With the detonation flame spraying process, it is possible to manufacture these super abrasive composites. Excellent embedment of the voluminous super abrasive particles into the matrix coating material can be realized to produce high quality composite layers for grinding applications of stone and concrete. In this paper, different diamond gradings as well as different volume contents of diamond in matrix are compared. Especially, the influence of particle size on its implantation efficiency is investigated and the influence of process and substrate temperature is analyzed. The thermal sprayed grinding tools are evaluated with respect to their microstructure as well as their grinding abilities. Compared to sintered diamond-bronze samples, the results of an adaptively designed grinding test for the machining of concrete are presented and analyzed.

Tillmann, W.; Vogli, E.; Nebel, J.

2008-12-01

193

Improved coal grinding and fuel flow control in thermal power plants  

DEFF Research Database (Denmark)

A novel controller for coal circulation and pulverized coal flow in a coal mill is proposed. The design is based on optimal control theory for bilinear systems with additional integral action. The states are estimated from the grinding power consumption and the amount of coal accumulated in the mill by employing a special variant of a Luenberger observer. The controller uses the rotating classifier to improve the dynamical performance of the overall system. The proposed controller is compared with a PID-type controller with available pulverized coal flow measurements under nominal conditions as well as when parameter uncertainties and noise are present. The proposed controller lowers the grinding power consumption while in most cases exhibiting superior performance in comparison with the PID controller.

Niemczyk, Piotr; Bendtsen, Jan Dimon

2011-01-01

194

Grinding induced martensite on the surface of rails  

DEFF Research Database (Denmark)

Rolling contact fatigue (RCF) is causing crack initiation and crack propagation in rails. Some types of RCF cracks are found to be associated with a white etching layer (WEL). A metallurgical investigation was carried out on a worn rail and the amounts of WEL at different positions on the rail were determined. Two different rail types R260 and R350HT that both had been ground by a grinding train were investigated. The rail sections, studied using optical and scanning electron microscopy, showed that the surface of both types of rails is covered with WELs. The hardness of the WEL is increased compared to the base material and the microstructural investigations reveal that a martensitic structure is present at the surface.

Rasmussen, C.J.; Zhang, Xiaodan

2014-01-01

195

Crystalline silica dust and respirable particulate matter during indoor concrete grinding - wet grinding and ventilated grinding compared with uncontrolled conventional grinding.  

Science.gov (United States)

The effectiveness of wet grinding (wet dust reduction method) and ventilated grinding (local exhaust ventilation method, LEV) in reducing the levels of respirable crystalline silica dust (quartz) and respirable suspended particulate matter (RSP) were compared with that of uncontrolled (no dust reduction method) conventional grinding. A field laboratory was set up to simulate concrete surface grinding using hand-held angle grinders in an enclosed workplace. A total of 34 personal samples (16 pairs side-by-side and 2 singles) and 5 background air samples were collected during 18 concrete grinding sessions ranging from 15-93 min. General ventilation had no statistically significant effect on operator's exposure to dust. Overall, the arithmetic mean concentrations of respirable crystalline silica dust and RSP in personal air samples during: (i) five sessions of uncontrolled conventional grinding were respectively 61.7 and 611 mg/m(3) (ii) seven sessions of wet grinding were 0.896 and 11.9 mg/m(3) and (iii) six sessions of LEV grinding were 0.155 and 1.99 mg/m(3). Uncontrolled conventional grinding generated relatively high levels of respirable silica dust and proportionally high levels of RSP. Wet grinding was effective in reducing the geometric mean concentrations of respirable silica dust 98.2% and RSP 97.6%. LEV grinding was even more effective and reduced the geometric mean concentrations of respirable silica dust 99.7% and RSP 99.6%. Nevertheless, the average level of respirable silica dust (i) during wet grinding was 0.959 mg/m(3) (38 times the American Conference of Governmental Industrial Hygienists [ACGIH] threshold limit value [TLV] of 0.025 mg/m(3)) and (ii) during LEV grinding was 0.155 mg/m(3) (6 times the ACGIH TLV). Further studies are needed to examine the effectiveness of a greater variety of models, types, and sizes of grinders on different types of cement in different positions and also to test the simulated field lab experimentation in the field. PMID:17763068

Akbar-Khanzadeh, Farhang; Milz, Sheryl; Ames, April; Susi, Pamela P; Bisesi, Michael; Khuder, Sadik A; Akbar-Khanzadeh, Mahboubeh

2007-10-01

196

Effect of different feed grinding fineness on the performances and digestive efficiency of growing rabbits  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, two experiments were carried out. In the first experiment, we studied the effect of commercial feeds, differing in the grinding level of their constituents (group C was fed a diet milled with the process used for commercial feeds, group F and group G received the same diet ground more finely or coarsely, respectively), on the growth performances of rabbits and on some characteristics of the caecum and its content. The second experiment, an in vivo digestibility experiment, was ...

Lambertini, Lamberto; Cavani, Claudio; Zucchi, Paola; Vignola, Giorgio

2000-01-01

197

Thermal aspects of grinding for surface integrity  

Science.gov (United States)

Thermal aspects of grinding are analyzed in detail since it is argued that temperature controls the effect of grinding on workpiece surface integrity. Transient and steady state heat partition in sliding contact is discussed in detail. This leads to a complete thermal model for heat partition and temperatures in surface grinding. Numerical predictions of the model are shown to agree with experimental results available in the literature. Effects of grinding conditions including real contact area ratio, thermal properties, feeds and speeds, and type of cut (down or up grinding) on heat partition and workpiece temperature are studied systematically. It is shown that the presence of the fluid inside the grinding zone can reduce the heat flux into the workpiece and workpiece temperature significantly. It is also found that some ratios of workpiece velocity to wheel velocity result in high temperatures and therefore should be avoided. This result provides a basis for the difference between conventional and creep-feed grinding regions. After obtaining temperature, an efficient and robust FFT approach is developed to obtain the thermal stress field induced by moving heat sources. Study of the 'hot spot' problem shows that the effect of hot spots on surface displacement and stress is small suggesting that grinding thermal stress is induced by the global temperature while local temperature controls metallurgical phase transformations. It is also shown that thermal stress is dominant on the global scale while the global scale mechanical stress is insignificant. Thus, the superior thermal properties of CBN compared to Alsb2Osb3 leads to low temperature and less deleterious residual stresses. Finally, spectral analysis is performed to evaluate contact behavior of the finished surface. This analysis shows that a good grinding process improves not only the magnitude of the surface roughness but the frequency content as well.

Ju, Yongqing

198

Welding of stainless steels preceeding rolling  

International Nuclear Information System (INIS)

The E.O. Paton Electrowelding Institute has done experimental work on single-sided consumable heated electrode welding of austenitic, ferritic and martensitic steels with thicknesses up to 6.0 mm for joining roll ends in rolling mill production. The properties of the welds were studied. In laboratory conditions the rollability of the seams was investigated and the effect of thermal treatment on rollability evaluated. The use of welding wire which gives seams of austenitic structure is desirable. Recommended regimes are discussed. It is shown that the possibility exists, in principle, of applying crushed-edge seam contact welding to the joining of stainless steel rolls. (author)

199

Evaluation of Grinding Wheel Surface by Means of Grinding Sound Discrimination  

Science.gov (United States)

In this study, a new technique of in-process evaluation of a grinding wheel surface is proposed. Some specific wheel surfaces are prepared as references by the appropriate truing and/or dressing procedure, and grinding sounds generated by these wheels are discriminated by analyzing the dynamic frequency spectrum by a neural network technique. In the case of a conventional vitrified-bonded alumina wheel, the grinding sound can be identified in the optimum network configuration. Therefore, this system can instantaneously recognize differences in the wheel surface with a good degree of accuracy insofar as the wheel conditions are relatively widely changed. In addition, the network can perceive wheel wear because the grain tips are flattened as grinding proceeds and the grinding sound becomes similar to that of a wheel generated with lower dressing feed. The resinoid-bonded cubic boron nitride (CBN) wheel is also discriminable when a grinding sound in a higher frequency range is analyzed.

Hosokawa, Akira; Mashimo, Kazufumi; Yamada, Keiji; Ueda, Takashi

200

A study of ball milling of powdered nuclear oxides  

International Nuclear Information System (INIS)

The nuclear fuel named MOX, Mixed Oxide Fuels, composed of about 3% to 10% of plutonium oxide in uranium allows to recycle plutonium in Pressurized Water Reactors Fuel performances and recycling are strongly connected with the homogeneity of the (U, Pu)O2 solid solution. Because of the low U and Pu cations interdiffusion during sintering, the quality of the mixing of the uranium and plutonium oxides powders obtained by dry ball milling conditions the homogeneity of the MOX fuel. This study contributes to a better understanding of this key step of the fuel fabrication process. The first part of this work deals with the objectives of the study, that is the maximum PuO2 and UO2 particles sizes that are acceptable after the milling operation as far as they will be resorbed by sintering. The second part investigates the micronizing of powders. The grinding mechanisms involved in the ball mill and their effect on the fragmentation of each single powder are analyzed. The third part concludes with the examination of the grinding/mixing of UO2 + CeO2 powders (cerium oxide powder simulates plutonium oxide) with the adjustment of a characterization technique on green pellets of the co-milled mix. This technique allows to evaluate the efficiency of the grinding/mixing by quantifying CeO2 particles size and their distribution in the mix as a function of grinding time, media size and rotational speed on the ball mill. Even with the most severe grinding conditions (increase of rotational speed or decrease of media size), a number of UO2 particles of size larger than the critical size acceptable after the grinding operation still persists. In contrast, from 2 h of grinding, the corresponding fraction associated with CeO2 particles does not exist. Therefore the penalizing parameter for the homogenization is not the PuO2 (CeO2) particles size, but rather that of UO2 aggregates. (author)

 
 
 
 
201

Automatic grinding apparatus to control uniform specimen thicknesses  

Science.gov (United States)

This invention is directed to a new and improved grinding apparatus comprising (1) a movable grinding surface, (2) a specimen holder, (3) a displacing device for moving the holder and/or grinding surface toward one another, and (4) at least three devices for limiting displacement of the holder to the grinding surface.

Bryner, Joseph S. (Pittsburgh, PA)

1982-01-01

202

Manufacturing of molybdenum tubes by pressing and skew rolling  

International Nuclear Information System (INIS)

A study was made on the quality of tube billets and molybdenum cast tubes, manufactured by pressing and the following skew rolling. The structure of the device for increasing the stability of exit side of screw rolling vacuum mill is suggested

203

Determination of cold rolling parameters providing required ductility of tubes  

International Nuclear Information System (INIS)

The effect of cold rolling parameters on change in plasticity of tubes of austenitic steels of the Kh18N10T type is shown. Main parameters affecting the decrease of plasticity are reduction in diameter and free reduction. Permissible values of these qualities providing tube fabrication on cold rolling mill witth the required value of relative elongation

204

Analysis of the cutting fluid influence on the deep grinding process with a CBN grinding wheel  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The application of cutting fluid in a deep grinding process is becoming more and more important, mainly where the cutting fluids are used as an "external" agent to the grinding conditions. The role of the fluid in grinding operations is in refrigeration of the workpiece, removal of the shavings, lub [...] rication of the grinding zone, and refrigeration and cleaning of the wheel. The efficiency of a cutting fluid will depend mainly of the type of fluid that will be used. In this work, the influences of the type of cutting fluid used in a deep grinding process of the steel VC131 using CBN grinding wheel are analyzed. Three different types of cutting fluids were used: a vegetable emulsion, a synthetic solution and a integral oil. The variables analyzed during and after the grinding process were the grinding force, the superficial roughness, the acoustic emission (EA), the temperature of the piece and the G ratio (relationship between the volume of material removed from the piece and the volume worn off the grinding wheel). The integral oil showed the best performance relative to the following output variables: EA, cutting force and G ratio. The vegetal emulsion was the fluid that best dissipated heat from the cutting region.

Ronaldo Yoshinobu, Fusse; Thiago Valle, França; Rodrigo Eduardo, Catai; Leonardo Roberto da, Silva; Paulo Roberto de, Aguiar; Eduardo Carlos, Bianchi.

205

On Surface Grind Hardening Induced Residual Stresses  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Grind hardening process utilizes the heat generated in the grinding area for the surface heat treatment of the workpiece. The workpiece surface is heated above the austenitizing temperature by using large values of depth of cut and low workpiece feed speeds. The workpiece undergoes martensitic phase transformation increasing its hardness in the surface layer. Usually compressive residual stresses are induced in the surface layer. In the present paper, modeling and prediction of the residual s...

Salonitis, Konstantinos

2014-01-01

206

Cylindricity control in precision centerless grinding  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A computer simulation method for investigating the form generation mechanism in the centerless grinding process is described. In this work, instantaneous change of the apparent depth of cut during grinding was modeled using absolute coordinate systems. The result of the simulation was not affected by the coordinate system (the location of the reference circle center and the radius of the reference circle). Also, analytical models of the interference phenomena at the contact points were develo...

Kim, Kang

1992-01-01

207

Quality assessment of rolled strip produced by compact versus conventional rolling  

International Nuclear Information System (INIS)

In continuous casting and rolling, the major factors that influence the quality are frequently interrelated and dependent on each other, with complex confluent relationships. When one of these factors changes, e.g. the temperature, not only is the rolling force affected, but the torque and surface properties, as kinematic boundary conditions, changes as well. The same is valid for the geometric quality parameters, consisting of thickness, profile, flatness, width and wedge, as well as for surface roughness. In order to be able to predict and improve the expected quality of the rolled sheet, detailed analysis of all these factors is necessary. The steel quality-producing of the new compact strip production technique as compared to as an integrated mill is studied by using modern data mining tools, primarily the Self-Organizing Map (SOM) approach. The data are gathered at several steel mills. In this paper data from two mills is analyzed using a bench marking approach. (author)

208

Mechanical of beryllium deformation and hardening at cold rolling  

International Nuclear Information System (INIS)

Beryllium rolling has been made on DUO-80 mills and quarto 15-35 with reductions of 0.2-1.0% for the run. A mechanism of beryllium deformation at cold rolling is determined by dislocations interaction with additive inclusions. The fracture of inclusion with microcracks formations is possible during deformation. At cold rolling of beryllium it is necessary to control the value of tensile stress in the metal to prevent the propagation of microcracks formed during inclusons cutting

209

Vibration characteristics analysis of a 20-high Sendzimir mill with localized defect on the working roller  

International Nuclear Information System (INIS)

The working roller associating with local defect of the twenty-high roll mill not only significantly affects the mill performance, but also reduces surface quality of the strip steel. In this paper, the roll mill model with local defect on the working roller is established. The dynamic rolling process is simulated using the Finite Element Analysis. Effects of the local defect on the vibration characteristics of the roll mill and the surface quality of the strip steel are presented. The calculated results are validated using experimental data.

210

Modelling of dynamic contact length in rail grinding process  

Science.gov (United States)

Rails endure frequent dynamic loads from the passing trains for supporting trains and guiding wheels. The accumulated stress concentrations will cause the plastic deformation of rail towards generating corrugations, contact fatigue cracks and also other defects, resulting in more dangerous status even the derailment risks. So the rail grinding technology has been invented with rotating grinding stones pressed on the rail with defects removal. Such rail grinding works are directed by experiences rather than scientifically guidance, lacking of flexible and scientific operating methods. With grinding control unit holding the grinding stones, the rail grinding process has the characteristics not only the surface grinding but also the running railway vehicles. First of all, it's important to analyze the contact length between the grinding stone and the rail, because the contact length is a critical parameter to measure the grinding capabilities of stones. Moreover, it's needed to build up models of railway vehicle unit bonded with the grinding stone to represent the rail grinding car. Therefore the theoretical model for contact length is developed based on the geometrical analysis. And the calculating models are improved considering the grinding car's dynamic behaviors during the grinding process. Eventually, results are obtained based on the models by taking both the operation parameters and the structure parameters into the calculation, which are suitable for revealing the process of rail grinding by combining the grinding mechanism and the railway vehicle systems.

Zhi, Shaodan; Li, Jianyong; Zarembski, A. M.

2014-09-01

211

Using of fluidized-bed jet mill to a super fine comminution of steel composite  

Directory of Open Access Journals (Sweden)

Full Text Available In many industries the demand for very fine material increases. In the metallurgical industry, for example, there is increasing use of the production of high density metal elements with the use of metallurgical powder composites. The use of powder composites requires prior their grinding. Unfortunately, the very fine grinding is not an easy process. The using for this purpose fluidized-bed jet mill was proposed in the paper. The attempts of grinding of metallurgical powder were carried out in the fluidized-bed jet mill. After the experiment analyses of particle size distribution of grinding products were performed. The results are presented in graphs. Analyses of the obtained results concluded that the grinding of very fine metallurgical composite is possible and produces positive results.

D. Urbaniak

2015-01-01

212

Delamination of hexagonal boron nitride in a stirred media mill  

International Nuclear Information System (INIS)

A scalable process for delamination of hexagonal boron nitride in an aqueous solution of the non-ionic surfactant TWEEN85 using a stirred media mill is presented. The size of the ZrO2 beads used as grinding media governs the dimensions of the ground boron nitride particles as atomic force microscopic investigations (AFM) reveal: the mean flakes thickness decreases from 3.5 to 1.5 nm and the ratio between mean flake area and mean flake thickness increases from 2,200 to 5,800 nm if the grinding media size is reduced from 0.8 to 0.1 mm. This result shows that a high number of stress events in combination with low stress energy (small grinding media) facilitate delamination of the layered material whereas at high stress energies in combination with a low number of stress events (large grinding media) breakage of the layers dominates over delamination. The results of particle height analyses by AFM show that few-layer structures have been formed by stirred media milling. This result is in agreement with the layer thickness dependence of the delamination energy for hexagonal boron nitride. The concentration of nanoparticles remaining dispersed after centrifugation of the ground suspension increases with grinding time and with decreasing grinding media size. After 5 h of grinding using 0.1 mm ZrO2 grinding media the yield of nanoparticle formation is about 5 wt%. The nanoparticles exhibit the typical Raman peak for hexagonal boron nitride at 1,366 cm?1 showing that the in-plane order in the milled platelets is remained.

213

Delamination of hexagonal boron nitride in a stirred media mill  

Energy Technology Data Exchange (ETDEWEB)

A scalable process for delamination of hexagonal boron nitride in an aqueous solution of the non-ionic surfactant TWEEN85 using a stirred media mill is presented. The size of the ZrO{sub 2} beads used as grinding media governs the dimensions of the ground boron nitride particles as atomic force microscopic investigations (AFM) reveal: the mean flakes thickness decreases from 3.5 to 1.5 nm and the ratio between mean flake area and mean flake thickness increases from 2,200 to 5,800 nm if the grinding media size is reduced from 0.8 to 0.1 mm. This result shows that a high number of stress events in combination with low stress energy (small grinding media) facilitate delamination of the layered material whereas at high stress energies in combination with a low number of stress events (large grinding media) breakage of the layers dominates over delamination. The results of particle height analyses by AFM show that few-layer structures have been formed by stirred media milling. This result is in agreement with the layer thickness dependence of the delamination energy for hexagonal boron nitride. The concentration of nanoparticles remaining dispersed after centrifugation of the ground suspension increases with grinding time and with decreasing grinding media size. After 5 h of grinding using 0.1 mm ZrO{sub 2} grinding media the yield of nanoparticle formation is about 5 wt%. The nanoparticles exhibit the typical Raman peak for hexagonal boron nitride at 1,366 cm{sup -1} showing that the in-plane order in the milled platelets is remained.

Damm, C., E-mail: cornelia.damm@fau.de; Koerner, J.; Peukert, W., E-mail: Wolfgang.Peukert@lfg.fau.de [University Erlangen-Nuremberg, Institute of Particle Technology (Germany)

2013-04-15

214

Research on the processing speed of cam grinding  

Science.gov (United States)

Cam Grinding is a special kind of non-circular machining. The processing speed of cam grinding has a major influence on cam machining precision. In this paper, decomposed the X-axis feed speed and C-axis velocity by the tangential speed and normal speed in accordance with the curvature circle at the point of cam profile grinding. Proposed the cam grinding processing speed model and linear velocity calculation formula, the processing experiment on the CNC camshaft grinding machine results show that the cam grinding speed model is correct. Constant angular speed grinding and constant linear speed grinding are analyzed respectively, which provides a theoretical basis for cam grinding processing speed optimization.

Peng, Baoying; Han, Qiushi

2011-05-01

215

Grinding technologies of small optical element molds  

Science.gov (United States)

The high-precision grinding technology is making contribution in every field, which is especially remarkable in the optics-related field. Lenses for digital camera and projector, which are mass-produced, for instance, are molded by the injection molding machine and glass molding-press machine. Concerning materials of high-precision molds, nickel alloy is mainly used in plastic-molding. And brittle material such as tungsten carbide and ceramic is used in glass-molding because the molding temperature is generally high. High-precision machining of nickel alloy is possible with a single-crystal diamond tool. Brittle material is ground by means of a diamond wheel, etc. Glass is being widely used for the lenses and other optical elements due to its favorable characteristics and life. As a result, needs for advancement of the high-precision grinding technology are being heightened. In grinding of small, fine and complex profiles, consideration for wheel truing and wear is a key point. Also, as many optical mold products are convex, mold profile is mainly concave. Especially, grinding of a small-aperture mold with small radius of curvature is difficult. In other words, a wheel whose diameter is larger than the radius of curvature of a mold to be ground cannot be used, and use of a small-diameter wheel is required inevitably. Influence of wheel wear and wheel diameter input errors at creation of grinding program becomes large. To eliminate such errors, a cycle of grinding, measurement and compensation grinding is normally repeated in mold machining until the target accuracy is obtained. Recently, needs for molding optical elements of small body of non-revolution such as prism and cylinder lens are on the increase, in addition to the body of revolution including lens. As one example, we introduce the compensation grinding and its results when grinding molds for an extremely small-aperture lens used for optical communication and a cylindrical lens array used for semi-conductor laser correction.

Katsuki, Masahide; Urushibata, Kazunori

2003-05-01

216

Transverse cylindrical grinding of a eutectic alloy  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english We report herein on a comparison of the performance of two different grinding wheels (conventional and CBN) in the transverse cylindrical grinding of a eutectic alloy. Three cutting conditions were tested: rough, semi-finishing and finishing. The parameters of evaluation were the cutting force, roug [...] hness and wheel wear. The optimal cutting force and roughness values were obtained when grinding with the conventional wheel, due to the superior dressing operation performed under every cutting condition tested. Although the CBN wheel presented the best G ratio values, they were lower than expected owing to the inappropriate dressing operation applied. Excessive wheel corner wear was detected in both wheels, caused by the grinding kinematics (transverse grinding) employed. In terms of cutting force and roughness, the conventional wheel proved to be the better choice under the conditions tested. However, in terms of the G ratio, a cost analysis is crucial to determine whether the differences between the wheels justify the use of the CBN wheel, in which case the dressing operation requires improvement.

E. C., Bianchi; V. L., Vargas; T. C., Magagnin; R. D., Monici; O., Vicari Filho; P. R. de, Aguiar; E. Jannone da, Silva.

217

Transverse cylindrical grinding of a eutectic alloy  

Directory of Open Access Journals (Sweden)

Full Text Available We report herein on a comparison of the performance of two different grinding wheels (conventional and CBN in the transverse cylindrical grinding of a eutectic alloy. Three cutting conditions were tested: rough, semi-finishing and finishing. The parameters of evaluation were the cutting force, roughness and wheel wear. The optimal cutting force and roughness values were obtained when grinding with the conventional wheel, due to the superior dressing operation performed under every cutting condition tested. Although the CBN wheel presented the best G ratio values, they were lower than expected owing to the inappropriate dressing operation applied. Excessive wheel corner wear was detected in both wheels, caused by the grinding kinematics (transverse grinding employed. In terms of cutting force and roughness, the conventional wheel proved to be the better choice under the conditions tested. However, in terms of the G ratio, a cost analysis is crucial to determine whether the differences between the wheels justify the use of the CBN wheel, in which case the dressing operation requires improvement.

Bianchi E. C.

2003-01-01

218

Modeling of the process of coal grinding  

Directory of Open Access Journals (Sweden)

Full Text Available The use of coal in the steel industry, similarly as in the whole national economy, is often preceded by its pre-treatment. Coal is mined in the form of big solids, but, being in such a form, it can’t be combusted, sintered, or gasified. Therefore, it needs to be appropriately grinding. In the paper results of the numerical prediction of the grain size distribution of the grinding coals are presented. The numerical computations were performed and then they were compared with grain size analysis results.

T. Wylecia?

2013-04-01

219

The thermal and metallurgical state of steel strip during hot rolling: Part II. Factors influencing rolling loads  

Science.gov (United States)

Traditional models for computing roll forces during hot rolling generally ignore the steep thermal gradients set up in the through-thickness direction due to roll chilling and deformation heat. In this paper, Alexander’s model has been modified to account for the effect of thermal gradients on roll forces. Flow stress data have been obtained by conducting tests on a cam plastometer and a Gleeble 1500 for a 0.05 pct carbon, a 0.34 pct carbon, and a 0.07 pct carbon with 0.024 pct niobium steel for temperatures and strain rates attained in each of the stands on Stelco’s Lake Erie Works (LEW) hot-strip mill. The hyperbolic sine equation has been shown to fit the data and is capable of predicting flow stress over a range of temperatures and strain rates. Simulations of the industrial operation have been conducted on the pilot mill at CANMET, and it has been shown by comparing predicted and measured roll forces that the friction coefficient is reduced from 0.3 to ˜R 0.35 to 0.25 in the presence of a lubricant. It has also been shown that incorporating the steep thermal gradients in the roll-bite zone increases predicted roll forces by 6 to ˜R 10 pct over the values computed based on centerline temperatures. The model has been validated also by comparing predictions with roll forces measured on the industrial mill.

Devadas, C.; Baragar, D.; Ruddle, G.; Samarasekera, I. V.; Hawbolt, E. B.

1991-02-01

220

Physical fabrication of colloidal ZnO nanoparticles combining wet-grinding and laser fragmentation  

Science.gov (United States)

Combination of wet-grinding and laser fragmentation is a promising approach to advance both methods: Laser fragmentation will be more efficient when combined with mechanical treatment and wet-grinding may take advance of the abrasion-free laser process to achieve fabrication of smaller particles. By mechanical pre-treatment of zinc oxide microparticles in a stirred-media mill, the starting material is activated by generation of crystallographic defects, which strongly enhance the efficiency of subsequent laser fragmentation. Picosecond-laser irradiation of mechanically treated and untreated microparticles suspended in water yielded in colloidal zinc oxide nanoparticles. Furthermore, nanoparticle productivity and properties can be controlled by variation of anionic surfactant concentration.

Wagener, Philipp; Lau, Marcus; Breitung-Faes, Sandra; Kwade, Arno; Barcikowski, Stephan

2012-09-01

 
 
 
 
221

Creep-feed grinding: A modern variant of the plane surface grinding process  

Science.gov (United States)

Creep feed and conventional grinding are compared. Specifications for an automated combined plane surface - creep feed grinder are presented. It must be possible to preprogram two different grinding cycles with an intervening dressing cycles. The automatic grinder must be equipped with a rigid feed system for the two-stage process, which can provide a steplessly controlled, stick-slip - free workpiece speed over the range 0.01 to 30 m/min. Spindle drive and spindle bearings are to be adapted to the increased demands placed on the machine system by the plungecut grinding technique. An efficient coolant system must be available to provide high pressures and throughput quantities.

Koenig, W.; Laeur-Schmaltz, H.

1982-07-01

222

Evaluation of roll compaction as a preparation method for hydroxypropyl cellulose-based matrix tablets  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Roll compaction was applied for the preparation of hydroxypropyl cellulose (HPC)-based sustained-release matrix tablets. Matrix tablets made via roll compaction exhibited higher dosage uniformity and faster drug release than direct-compacted tablets. HPC viscosity grade, roll pressure, and milling speed affected tablet properties significantly. Roll compaction seems to be an adequate granulation method for the preparation of HPC-based matrix tablets due to the simplicity of the process, less ...

Jeon, Imjak; Gilli, Tiziana; Betz, Gabriele

2011-01-01

223

Effect of deep cryogenic treatment on the microstructure and wear performance of Cr-Mn-Cu white cast iron grinding media  

Science.gov (United States)

The phase transformation and grinding wear behavior of Cr-Mn-Cu white cast irons subjected to destabilization treatment followed by air cooling or deep cryogenic treatment were studied as a part of the development program of substitute alloys for existing costly wear resistant alloys. The microstructural evolution during heat treatment and the consequent improvement in grinding wear performance were evaluated with optical and scanning electron microscopy, X-ray diffraction analysis, bulk hardness, impact toughness and corrosion rate measurements, laboratory ball mill grinding wear test etc. The deep cryogenic treatment has a significant effect in minimizing the retained austenite content and converts it to martensite embedded with fine M7C3 alloy carbides. The cumulative wear losses in cryotreated alloys are lesser than those with conventionally destabilized alloys followed by air cooling both in wet and dry grinding conditions. The cryotreated Cr-Mn-Cu irons exhibit comparable wear performance to high chromium irons.

Vidyarthi, M. K.; Ghose, A. K.; Chakrabarty, I.

2013-12-01

224

Energy requirement for fine grinding of torrefied wood  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study is to investigate the influence of torrefaction on wood grinding energy. Wood chips were torrefied at different temperatures and durations. The energy required to obtain fine powder was measured. Particle size analyses were carried out on each powder sample. It is showed that torrefaction decreases both grinding energy and particle size distribution. A criterion to compare grindability of natural and torrefied wood is proposed. It takes into account both grinding energy and particle size distribution. It accounts the energy required for grinding particles to sizes inferior to 200 {mu}m, for given grinding conditions. Torrefaction is characterised by the anhydrous weight loss (AWL) of wood. For AWL inferior to around 8%, grinding energy decreases fast. Over 8%, grinding energy decreases at a slow rate. Particle size distribution decreases linearly as the AWL increases. Both for spruce and beech, the grinding criterion is decreased of 93% when the AWL is around 28%. (author)

Repellin, Vincent; Govin, Alexandre; Guyonnet, Rene [Department of Powder and Multi-Components Materials (PMMC), SPIN Research Center, Ecole des Mines de Saint Etienne (EMSE), 158 Cours Fauriel, F-42023 Saint-Etienne (France); Rolland, Matthieu [Process Developments and Engineering Division, Chemical Engineering Department, Institut Francais du Petrole (IFP-Lyon), F-69390 Vernaison (France)

2010-07-15

225

KINEMATICS OF MATERIAL REMOVAL AND FORMING OF SURFACE AT GRINDING  

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Full Text Available The mathematical model of kinematics of material removal and a forming of surfaces isdeveloped at grinding. Conditions of increase of productivity of processing are defined and newkinematic schemes of high-performance grinding are offered

Feodor NOVIKOV

2013-05-01

226

Underground milling of uranium ores  

International Nuclear Information System (INIS)

Full text: This paper presents and analyzes the new concept of underground milling of high-grade uranium ore. Compared to conventional milling on surface, the underground milling scheme appears to offer significant cost savings and a lower environmental impact. The paper describes the underground milling scheme, presents process flowsheets and plant layouts, and provides an assessment of potential benefits from underground milling. In response to the current supply/demand situation for uranium, there has been, for the past few years, a 'uranium rush' in many parts of the world, including the resource-rich Athabasca basin situated in northern Saskatchewan. In a recent count, there were over forty uranium companies looking for uranium in this region. Positive results from any of these exploration activities could, depending on their location, potentially provide a source of additional feedstock for any of the existing milling centres in northern Saskatchewan and/or result in the establishment of additional new milling capacity. Underground milling would be considered in the latter instance. The above flowsheet shows the basics of the proposed underground milling scheme, which assumes the existence of a high-grade underground uranium mine, similar to the current McArthur River mine or the planned Cigar Lake mine. Grinding, leaching, solid/liquid separation and tailings deposition are all carried out underground. Leach liquor is pumped to surface for impurity removal, precipitation and drying. The impurities, removed as chemical precipitates, are moved back underground for disposal. Expected environmental benefits are significant and include reduction of surface visual impact, leach residues remain underground, and no tailings management facility on surface. Indeed the process residue is arguably more isolated from the environment than was the ore before mining. Contaminant transport from the stored tailings to surface waters is extremely slow. Application of membrane technology to water treatment for the underground milling scheme is expected to provide an aqueous effluent with minimal loading to the environment. In addition to these substantial environmental benefits, underground milling is expected to give a capital cost saving on the order of 35% and an operating cost saving on the order of 30% relative to conventional mining and milling. (author)

227

Critical review of Nanofluid Minimum Quantity Lubrication for Grinding application  

Directory of Open Access Journals (Sweden)

Full Text Available In recent years, the environment has become one of the most important subject. Emulsion-based cooling fluids are used in grinding for a variety of reasons such as improving surface finish, wheel life, flushing away chips, reducing workpiece thermal deformation. Due to large fluid delivery an extensive amount of mist is generated during grinding process. The workers who breathe in this hazardous mist is having health hazard. There are two alternative for large cutting fluids. One is dry grinding and another is near dry grinding also known as minimum quantity lubrication. MQL grinding refers to the delivery of minute quantity of fluid via an aerosol to the grinding zone. The typical flow rate of grinding fluid for MQL fluid consumption is generally 20-100 ml/hour. Although numerous advantages were found for MQL grinding compared with the conventional technique and dry grinding. The cooling and lubrication performance of the grinding fluid is the key technical area for the success application of MQL grinding process. Nanofluid has emerged as a promising solution to this problem. Nanofluid is a new class of fluids engineered by dispersing nanometer-size solid particles into base fluids such as water, lubrication oils. The excellent properties of the nanofluid makes very attractive in cooling and lubricating application in manufacturing. . This study provides a review of research in this field with focus on use of nanofluids in grinding applications.

Mr. Prashant J. Patil,

2014-08-01

228

Understanding Rolle's Theorem  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports on an experiment studying twelfth grade students’ understanding of Rolle’s Theorem. In particular, we study the influence of different concept images that students employ when solving reasoning tasks related to Rolle’s Theorem. We argue that students’ “container schema” and “motion schema” allow for rich concept images.

REVATHY PARAMESWARAN

2009-01-01

229

The Inlet Engine Valves Grinding Using Different Types of Cutting Fluids and Grinding Wheels  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In this paper an experimental research is presented in which different types of cutting fluids (a cutting oil and three different types of soluble oils) and grinding wheels (alumina and vitrified CBN) were tested in the inlet engine valves grinding. As evaluation parameters the workpiece residual st [...] ress and the grinding wheel wear were analyzed. The cutting fluid and the grinding wheel types adopted resulted in changes in all the parameters, due to the different lubricant abilities among the fluids and due to the differences in the mechanical and thermal properties among the abrasives tested. For grinding this steel, the CBN wheel is the best choice, mainly due to compressive residual stress results obtained for all cutting fluids tested. The cutting oil is the most adequate cutting fluid to be used, due to its higher lubricity and ability in keeping the wheel sharp for longer periods of time, reducing the overall grinding energy and the thermal damage.

Eraldo Jannone da, Silva; Eduardo Carlos, Bianchi; João Fernando Gomes de, Oliveira; Paulo Roberto de, Aguiar.

230

High pressure grinding moving ahead in copper, iron, and gold processing  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english High pressure grinding roll (HPGR) technology is used in an increasingly diverse range of applications, predominantly iron ore , gold and diamonds. KHD Humboldt Wedag HPGRs are applied world-wide, and consistently prove to be well designed and reliable operating units, with their performance meeting [...] the pre-set standards. This publication summarizes some of the features and experiences for recent applications in treatment of copper ore, coarse iron ore, and gold ore. Summary data of roll surface wear life and operating data are given, together with operational observations. In addition, effects of feed segregation and truncated feed are discussed, as well as the implications of a product recycle flow sheet.

F.P., van der Meer; W., Maphosa.

2012-07-01

231

High pressure grinding moving ahead in copper, iron, and gold processing  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english High pressure grinding roll (HPGR) technology is used in an increasingly diverse range of applications, predominantly iron ore , gold and diamonds. KHD Humboldt Wedag HPGRs are applied world-wide, and consistently prove to be well designed and reliable operating units, with their performance meeting [...] the pre-set standards. This publication summarizes some of the features and experiences for recent applications in treatment of copper ore, coarse iron ore, and gold ore. Summary data of roll surface wear life and operating data are given, together with operational observations. In addition, effects of feed segregation and truncated feed are discussed, as well as the implications of a product recycle flow sheet.

F.P., van der Meer; W., Maphosa.

232

Mathematical Aspect for Worm Grinding Using a Toroidal Tool  

Directory of Open Access Journals (Sweden)

Full Text Available This paper is an attempt to improve the accuracy of the worm gearings with concave profile of the worm thread by using a new generating surface of grinding wheel to eliminate the lacks of the popular worm gearings and extensioning the field of investigation. The present study propose grind concave profile worms by means of toroidal tool - grinding wheel which section in the axial plane is an arc of parabola. The generating equation of the grinding wheel surface and the arrangement of this wheel with respect to the worm during grinding of its thread was determined.

Tareq A. Abu Shreehah

2004-01-01

233

A new transducer for roll gap measurements of the roll pressure distribution and the friction condition in cold flat rolling  

DEFF Research Database (Denmark)

Background/purpose The only way to establish the true rolling pressure and the true friction condition in cold rolling is to conduct measurements in the roll bite. A new transducer design is therefore proposed, this to overcome problems in previous measurements in the past 70 years. Method The new idea is to increase the contact surface of the transducer, to be larger than the arc of contact. This is in the opposite way, compared to the smaller and smaller contact pin design that has been prevailing. Results The measurements where conducted during cold dry rolling of both copper strips and stainless steel strips in a pilot mill. The recordings were selected from a steady state with no disturbance from the material flow. The transducer was able to simultaneously measure both the normal pressure and the friction stress. An estimation of the coefficient of friction was accordingly performed. Conclusions The new transducer works very well, it was seen to be robust and able to avoid signal disturbance. The pressure and friction stress distribution results was as expected by the authors and a good reproducibility, together with a proven agreement between recorded signals and signals simulated. Keywords Friction stress, normal pressure distribution, roll bite measurements, cold flat rolling of metals

Wanheim, Tarras; Henningsen, Poul

2005-01-01

234

OPTIMISE - Deliverable D4.1, Deliver preliminary samples made by two axis rolling to UNIVERSITY OF TWENTE, month 6  

DEFF Research Database (Denmark)

This report describes the preliminary samples that were delivered to University of Twente (UT). It was decided not to deliver samples made by two axis rolling but instead deliverer samples which were reduce by square drawing and flat rolled in a standard rolling mill. The reason for that will be explained before the results from the actual deliverables will be described.

Eriksen, Morten

2002-01-01

235

Investigation on Surface Roughness in Cylindrical Grinding  

Science.gov (United States)

Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse-cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C- programming.

Rudrapati, Ramesh; Bandyopadhyay, Asish; Pal, Pradip Kumar

2011-01-01

236

Grinding Characteristics of Reaction Bonded Silicon Carbide  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Surface topography, surface residual stress and bending strength of RBSiC ground using diamond wheel were studied. Grinding RBSiC is removed mainly by brittle fracture and lightly by ductile cutting. With the increase of down feed, surface roughness Ra increases. Burnishing with no down feed can improve the Ra in some way. With increasing down feed, the compressive residual stress decreases because of an inadequately cooling effect. Compare with the specimens grounded using 0.9 ?m/s, those...

Yao Wang, Zhang Yu-min

2012-01-01

237

Modeling recrystallization kinetics during strip rolling  

Energy Technology Data Exchange (ETDEWEB)

In order to simulate the microstructural evolution during hot strip rolling, double-hit compression tests have been carried out on plain carbon steels. Using the softening data obtained by these tests, mathematical models were developed to predict the overall kinetics of static recrystallization under roughing and finishing mill conditions. These models include the effects of deformation temperature, applied strain, strain rate and initial austenite grain size. Predictions based on these models are in reasonable agreement with the present experimental results.

Sun, W.P.; Hawbolt, E.B.; Meadowcroft, T.R. [Univ. of British Columbia, Vancouver (Canada). The Centre for Metallurgical Process Engineering

1995-01-01

238

Development of concrete floor grinding machine  

International Nuclear Information System (INIS)

In order to provide a flat concrete floor, we have developed a new concrete grinding machine, which is equipped with a rotating diamond wheel, mounted on XYZ translator controlled by PLC digital program controller. By measuring the surface level for several points on work area, and set the target level by external reference, then start machine grinding according to programmed data. It typically takes a few hours to complete one working area of 1 m x 1 m square for 5 mm grind. Current machine is capable to finish levelling within 50 ?m for 1 m span, and surface roughness rms 20 ?m for 1 m, and 10 ?m for 0.1 m. Once we have a flat floor, we may locate hardware component directly on it, without using base plate and level adjustment screws, thus the connection between the component and the concrete floor becomes tight, which provides a very large equivalent mass on the component (a part of the ground becomes linked virtual mass to the component), which drastically reduces the mechanical vibration. This type of technique will be also applicable to industrial use, such as, setting a fine mechanical machining tool or process equipments which require quiet environment. (author)

239

Silica exposure in hand grinding steel castings.  

Science.gov (United States)

Exposure to silica dust was studied in the grinding of castings in a steel foundry that used conventional personal sampling methods and new real-time sampling techniques developed for the identification of high-exposure tasks and tools. Approximately one-third of the personal samples exceeded the National Institute for Occupational Safety and Health recommended exposure limit for crystalline silica, a fraction similar to that identified in other studies of casting cleaning. Of five tools used to clean the castings, the tools with the largest wheels, a 6-in. grinder and a 4-in. cutoff wheel, were shown to be the major sources of dust exposure. Existing dust control consisted of the use of downdraft grinding benches. The size of the casting precluded working at a distance close enough to the grates of the downdraft benches for efficient capture of the grinding dust. In addition, measurements of air recirculated from the downdraft benches indicated that less than one-half of the respirable particles were removed from the contaminated airstream. Previous studies have shown that silica exposures in the cleaning of castings can be reduced or eliminated through the use of mold coatings, which minimize sand burn-in on the casting surface; by application of high-velocity, low-volume exhaust hoods; and by the use of a nonsilica molding aggregate such as olivine. This study concluded that all these methods would be appropriate control options. PMID:1317091

O'Brien, D; Froehlich, P A; Gressel, M G; Hall, R M; Clark, N J; Bost, P; Fischbach, T

1992-01-01

240

Dressing of diamond grinding wheels by abrasive water jet for freeform optical surface grinding  

Science.gov (United States)

During the ultra-precision grinding of a large aperture mirror made of RB-SiC, the grinding wheel becomes dull rapidly, which will lead to an increase of grinding force and a decrease of grinding ratio. In this paper, diamond grinding sticks were dressed with micro SiC abrasive water jet and water jet. Through single factorial experiments, the influence of jet pressure on the dressing performance was investigated. To analyze and evaluate the effect of dressing quantitatively, the 3D roughness and the wheel topography were measured and compared with laser scanning confocal microscope before and after dressing. The experimental results show that the abrasive grains are well protruded from binder and the distribution of the abrasive grains becomes uniform after dressing by abrasive water jet when the dressing parameters are properly selected. The dressing performance of abrasive water jet is much better than water jet. For dressing ultra-fine grit size wheels, the abrasive size of the jet should be smaller than the wheel grit size to achieve a better result. The jet pressure is an obvious influence factor of the surface topography.

Wang, Wei; Yao, Peng; Li, Chengwu; Huang, Chuanzhen; Wang, Jun; Zhu, Hongtao; Liu, Zengwen

2014-08-01

 
 
 
 
241

GEOMETRICAL CHARACTERIZATION OF MICRO END MILLING TOOLS  

DEFF Research Database (Denmark)

The milling process is one of the most common metal removal operation used in industry. This machining process is well known since the beginning of last century and has experienced, along the years, many improvements of the basic technology, as concerns tools, machine tools, coolants/lubricants, milling strategies and controls. Moreover the accuracy of tool geometry directly affects the performance of the milling process influencing the dimensional tolerances of the machined part, the surface topography, the chip formation, the cutting forces and the tool-life. The dimensions of certain geometrical details, as for instance the cutting edge radius, are determined by characteristics of the manufacturing process, tool material, coating etc. While for conventional size end mills the basic tool manufacturing process is well established, the reduction of the size of the tools required for the manufacturing of miniature parts by micro milling puts further challenges on to the manufacturing process. The whole geometry of the tools cannot be directly downscaled with the tool diameter. Besides the physical limit in the reduction of the cutting edge radius constituted by the grain size of sintered carbides the error motion during the grinding wheels do not allow using identical paths for tools having differences in diameter of more than one order of magnitude. Thus grinding paths for micro and mills are simplified in comparison to those for larger tools of similar shape. [1] The aim of the present report is to develop procedures for the geometrical characterization of micro end milling tools in order to define a method suitable for the quality assurance in the micro cutting field.

Bariani, Paolo

2004-01-01

242

Production of talc nano sheets via fine grinding and sonication processes  

International Nuclear Information System (INIS)

Fine grinding of high purity talc in jet mill at low grinding pressure was carried out by varying the feed rate and classifier rotational speed. These ground particles were sonicated in laboratory ultrasonic bath by varying the soniction period at five levels. The ground and sonicated particles were characterized in terms of particle size and particle size distribution. Mechanochemical and sonochemical effect of talc was determine via X-ray diffraction. Particle shape and surface texture of the ground and sonicated product was determined via scanning electron microscope and transmission electron microscope. The ground particle size exhibited particle size below 10 ?m with narrow size distribution. The reduction of peak intensity in (002) plane indicated the layered structure has been distorted. The sonicated talc shows that the thickness of the talc particles after the sonication process is 20 nm but the lateral particle size still remains in micron range. The reduction of the XRD peak intensity for (002) plane and thickness of sonicated talc as shown in SEM and TEM micrographs proves that fine grinding and sonication process produces talc nano sheets. (author)

243

Investigation into power parameters during rapid rolling of high-alloyed and difficult-deformed alloys with technological lubricants  

International Nuclear Information System (INIS)

The effect of the rolling speed (from 4.5 to 15.7 m/s) and rolling lubricants on the force prameters involved in the rolling of high-alloy and high-resistance alloys has been studied under laboratory conditions on a 300 high-speed mill. The experimental rolling of high-alloy and high-resistance alloys has shown the possibility of rolling such alloys at high speed without adverse affecting their physicomechanical properties, with a view to increasing the mill production and for a fuller utilization of their narrow rolling temperature range. Therewith, the use of rolling lubricants reduces the metal pressure on the rolls by 15 to 20%

244

Mechanical grinding of UMo alloy interaction of the UMo-Al system  

International Nuclear Information System (INIS)

Since the beginning of the research nuclear reactors in the CCHEN, already 32 years ago, the fuels for both reactors have been imported. Nevertheless, since 1997 these fuel elements have been manufactured for CCHEN in their Fuel Elements Production Plant, PEC, located in the Center of Nuclear Studies in Lo Aguirre. This it is a licensed installation and standard low certificate ISO that covers the internal demand and it has a capacity for development about fissile material, design of fuel elements and materials for irradiation in experimental nuclear reactors. Nowadays developments are oriented to obtain higher uranium density that those obtained with uranium silicides (U3Si2), like the U-Mo alloys fuels. The utilization of particulate material is usually thing for this type of fuels and in the case of the U-Mo alloys, is presented like a solid solution ? (cubic), meta stable. This phase is ductile and therefore complicates the obtaining of dust by traditional methods of comminuting. This work delivers a synthesis of the present state of the U-Mo fuels development in the CCHEN, besides detailing U-Mo/Al interaction tests results and of production of powder by not conventional comminuting mechanical techniques, as the cryogenic grinding in atritor mill, grinding of high energy in SPEX mill and grinding in Ti, HSS or WC knives mill. The tests of grinding were carried out since 20 minutes to 20 hours, depending on the technique utilized. The efficiency of each methodology is reported, with values varying since 3.6% until 100% for the particle size under 150 ?. As for the fines fraction (? 45 ?) this varied since 29% until 70.8% depending on the methodology applied. Results of analysis are discussed of DRX, particle size distribution, morphology and SEM. Regarding the chemical interaction, it's confirmed the presence of binary and ternary compounds in the U-Mo-Al system as product of thermally activated processes. In general can be concluded that the U-Mo fuels development program of the CCHEN advances according to the program and virtually in parallel with the vanguard nuclear centers. As conclusion the chemical interaction is a factor that should be controlled in order to avoid the excessive increase of volume in fuel plates, while the main fracture mechanism registered in the comminuting of the alloy U-Mo, in its different conditions, was the abrasion of the material, that exhibits a ductile behavior, and therefore the deformation it dominates and fragmentation affected the efficiency of the reduction (HC)

245

Off-line calculation of pass schedule for hot rolling stainless steel strip and establishment of model parameters for on-line set up calculation  

International Nuclear Information System (INIS)

In this paper, the method to calculate the roughing and finishing rolling forces is described. The way to establish the model parameters for on-line process set up calculation during developing hot rolling stainless steel strip in 2050mm hot rolling mill of Baosteel, is also introduced. Rolling test shows that the rolling forces calculated by on-line process set up model agree well with measured data. (author)

246

Study Friction Distribution during the Cold Rolling of Material by Matroll Software  

International Nuclear Information System (INIS)

Rolling process is one of the most important ways of metal forming. Since the results of this process are almost finished product, therefore controlling the parameters affecting this process is very important in order to have cold rolling products with high quality. Among the parameters knowing the coefficient of friction within the roll gap is known as the most significant one. That is because other rolling parameters such as rolling force, pressure in the roll gap, forward slip, surface quality of sheet, and the life of work rolls are directly influenced by friction. On the other hand, in rolling calculation due to lake of a true amount for coefficient of friction a supposed value is considered for it. In this study, a new software (Matroll), is introduced which can determine the coefficient of friction (COF) and plot the friction hills for an industrial mill. Besides, based on rolling equations, it offers about 30 rolling parameters as outputs. Having the rolling characteristics as inputs, the software is able to calculate the coefficient of friction. Many rolling passes were performed on real industrial aluminum mill. The coefficient of friction was obtained for all passes. The results are in good agreement with the findings of the other researchers

247

Microstructure Characterization of Mechanically Activated Talc in Jet Mill Using XRD Line Broadening Technique  

Science.gov (United States)

Fine grinding process of talc was carried out in jet mill by varying the operational parameter such as feed rate, classifier frequency and grinding pressure. The size reduction and mechanochemical effect of talc take place simultaneously as jet mill is an energy intensive grinding mill. The minimum particle size obtained was 4.28 ?m with span value of 1.30. The crystallinity values of ground product ranging from 71% to 91%. The crystallite size of the ground silica is ranging from 147.69 nm to 353.72 nm whilst the lattice strain was ranging from 0.08 to 0.20. After sonication process in ulrea sonic bath, the ground talc were in nano sheet where its thickness was around 20 nm.

Palaniandy, S.; Azizli, K. A. M.

2010-03-01

248

CALCULATION OF SURFACE ROUGHNESS PARAMETERS FOR EXTERNAL CYLINDRICAL GRINDING  

Directory of Open Access Journals (Sweden)

Full Text Available The method of calculating the surface roughness parameters for an external cylindrical grinding is considered. The offered calculation relations are taken account of production mode parameters, the grain size of the grinding wheel and the change of state of the tool working surface during machining. This allows to assess the impact of multipass grinding process and to predict the kinetics of changes in surface roughness.

Vladimir BOGUTSKY

2013-05-01

249

REVIEW OF DRESSING AND TRUING OPERATIONS FOR GRINDING WHEELS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Grinding is an operation applied in almost every type of manufacturing process. It aims to produce high surface finish and to maintain close tolerances in the manufactured product. To make the grinding operation more productive and efficient, dressing and truing operations are performed on the grinding wheels. Various techniques are available and are used for the same. Since many permutations and combinations exists among the factors like economics, efficiency, accuracy, complexity, etc. of t...

UJJAWAL MAYANK SRIVASTAVA

2013-01-01

250

a Traffic-Dependent Acoustical Grinding Criterion  

Science.gov (United States)

On most lines of the Dutch railway network, where a substantial amount of block-braked trains have rough wheels, the average wheel roughness dominates over the rail roughness. Therefore, reducing wheel roughness is top priority in the Netherlands. However, for the situations where rail roughness exceeds wheel roughness, this roughness can be lowered at acceptable cost. The high rail roughness is often due to rail corrugation which can be removed by grinding. A method has been developed to assess periodically the rail roughness on each railway line of the network, to compare it with the average wheel roughness for that line and to determine whether a noise reduction can be achieved by grinding the rail. Roughness measurements can be carried out with an instrumented coach. The two axle-boxes of a measurement wheelset are equipped with accelerometers. Together with the train speed and the right frequency filter, the accelerometer signal is used to produce a wavelength spectrum of the rail roughness. To determine the average wheel roughness on a given line, the so-called Acoustical Timetable can be used. This database comprises train types, train intensities and train speeds for each track section in the Netherlands. An average wheel roughness spectrum is known for each type of braking system. The number of trains of each type passing by on a certain track section determine the average roughness. Analysis of the data shows on which track sections the rail roughness exceeds the wheel roughness by a specified level difference. If this track section lies in a residential area, the decision can be made to grind this piece of track to reduce the noise production locally. Using this methodology, the noise production can be kept to a minimum, determined by the local average wheel roughness.

DINGS, P.; VERHEIJEN, E.; KOOTWIJK-DAMMAN, C.

2000-03-01

251

Minimizing the edge buckling of the cold roll-forming process  

Science.gov (United States)

In this work, the cold roll-forming process was numerically simulated by MSC SuperForm 2002 software based on finite element method. The strips were modelled with U-profile and a pre-punched hole located at the web zone was introduced. Two different configurations of the roll-forming mills were simulated, named as the Conventional and Curved. The conventional roll-forming mill was obtained by using the same diameters of the bottom rolls. The downhill roll-forming mill was achieved by increasing the diameters of the bottom rolls. This study investigated the occurrence of edge buckling in the hole lateral edge of the pre-punched sheet during the forming process. It could be concluded that, during the cold roll-forming process, reducing or even eliminating the compression stress in the web zone by the downhill roll-forming mill is possible to minimize occurrence of the edge buckling in the hole lateral edge of the pre-punched sheet during the forming process.

Cavaguti, M.; Ferreira, J. V.

2010-06-01

252

Minimizing the edge buckling of the cold roll-forming process  

International Nuclear Information System (INIS)

In this work, the cold roll-forming process was numerically simulated by MSC SuperForm 2002 software based on finite element method. The strips were modelled with U-profile and a pre-punched hole located at the web zone was introduced. Two different configurations of the roll-forming mills were simulated, named as the Conventional and Curved. The conventional roll-forming mill was obtained by using the same diameters of the bottom rolls. The downhill roll-forming mill was achieved by increasing the diameters of the bottom rolls. This study investigated the occurrence of edge buckling in the hole lateral edge of the pre-punched sheet during the forming process. It could be concluded that, during the cold roll-forming process, reducing or even eliminating the compression stress in the web zone by the downhill roll-forming mill is possible to minimize occurrence of the edge buckling in the hole lateral edge of the pre-punched sheet during the forming process.

253

Rolling friction and bistability of rolling motion  

CERN Document Server

The rolling motion of a rigid cylinder on an inclined flat viscous surface is investigated and the nonlinear resistance force against rolling, $F_R(v)$, is derived. For small velocities $F_R(v)$ increases with velocity due to increasing deformation rate of the surface material. For larger velocity it decreases with velocity due to decreasing contact area between the rolling cylinder and the deformed surface. The cylinder is, moreover, subjected to a viscous drag force and stochastic fluctuations due to a surrounding medium (air). For this system, in a wide range of parameters we observe bistability of the rolling motion. Depending on the material parameters, increasing the noise level may lead to increasing or decreasing average velocity.

Pöschel, T; Brilliantov, N; Zaikin, A; Poeschel, Thorsten; Schwager, Thomas; Brilliantov, Nikolai; Zaikin, Alexei

2005-01-01

254

Model Predictive Control for an Industrial SAG Mill  

DEFF Research Database (Denmark)

We discuss Model Predictive Control (MPC) based on ARX models and a simple lower order disturbance model. The advantage of this MPC formulation is that it has few tuning parameters and is based on an ARX prediction model that can readily be identied using standard technologies from system identication. When applied to MIMO systems we call this controller a MIMO-ARX based MPC. We use an industrial Semi-Autogenous Grinding (SAG) mill to illustrate the performance of this controller. SAG mills are the primary units in a grinding chain and also the most power consuming units. Therefore, improved control of SAG mills has the potential to signicantly improve eciency and reduce the specic energy consumption for mineral processes. Grinding circuits involving SAG mills are multivariate processes. Commissioning of a control system based on a classical single-loop controllers with logic is time consuming, while MPC has the potential to both improve the control performance and the commissioning time and expertise required. The simulation results demonstrate that the MPC based on a MIMO-ARX model is able to provide nice control performance measured by its ability to track an output reference and reject unknown disturbances. Furthermore, the method used to design the controller represents a systematic method that can be automatized for wide-spread deployment in industrial environments.

JØrgensen, John Bagterp

2012-01-01

255

Combustion performance characteristics of fine grind fuels  

Energy Technology Data Exchange (ETDEWEB)

The objectives of this project include: (1) the development of an engineering data base which will provide detailed information on the properties of Beneficiated Coal-Based Fuels (BCFs) influencing combustion, ash deposition, ash erosion, particulate collection, and emissions; and (2) the application of this technical data base to predict the performance and economic impacts of firing the BCFs in various commercial boiler designs. To date, twelve beneficiated coal-based fuels have been acquired through PETC and tested at ABB Power Plant Laboratories Fireside Performance Test Facility (FPTF). The results from these fuels indicate that firing the BCFs improved furnace heat transfer and fly ash erosion compared to their respective feed coals. This paper presents the results from a series of combustion test runs recently conducted in the FPTF to address the effect of fuel fineness on performance. A conventionally cleaned at the mine Pittsburgh No. 8 (Emerald mine, Green County, Pennsylvania, Cyprus Coal Company) was acquired and prepared at three grinds (standard, fine and ultra-fine grinds) to evaluate the effect of fuel fineness on combustion performance. The three fuels were tested at firing rates ranging from 3.0 {times} 10{sup 6} Btu/h to 4.0 {times} 10{sup 6} Btu/h, at standard (no staging) and two staged firing conditions.

Chow, O.K.; Levasseur, A.A.

1996-12-31

256

Microsurface finishing of borosilicate glass with magnetic fluid grinding  

Science.gov (United States)

A new microsurface finishing method of local area using magnetic fluid, abrasive grains and magnet is proposed. The profile of grinding surface of borosilicate glass is observed as a function of grinding time and magnetic fluid strength. Magnetic fluid and magnetic field can provide efficient and uniform finishing in a local area.

Umehara, N.; Mizuguchi, S.; Kato, K.; Nakamara, S.

1993-04-01

257

Effects of grinding on certain crystalline structures; Influence de broyage sur quelques structures cristallines  

Energy Technology Data Exchange (ETDEWEB)

The effects of grinding on certain crystalline substances (ZnO, ZnS, Sb), have been studied using X-ray diffraction and electron microscopy. The treatments were carried out using a vibrating mill which involves a higher energy than more conventional equipment such as ball-mills. Various methods have been proposed for determining the width of the intrinsic profile ({beta}). In the case of zinc oxide it has been shown possible to differentiate the respective contributions of the fragmentation effects and of lattice deformation effects to the overall effects of the grinding. For the two types of zinc sulfide (blend and Wurtzite) it has been shown that the blend-wurtzite) transition point is very much decreased, and that the rate of transformation of wurtzite into the stable form (blend) at room temperature is considerably increased by the grinding. In the case of antimony, the method of fragmentation shows the existence of an anisotropy which appears to be connected with easily cleavable planes. These observations show that in the case of grinding carried out with sufficient energy, the accumulation of this energy in the matter through the creation of lattice defects can accelerate the reaction rate or bring about physical transformations. (author) [French] Les effets du broyage sur certains corps cristallises (ZnO, ZnS, Sb) ont ete etudies a l'aide de la diffraction de rayons X et de la microscopie electronique. Les broyages ont ete effectues au moyen d'un vibro-broyeur qui met en jeu une energie superieure par rapport aux appareils plus conventionnels tels que les broyeurs a boulets. Diverses methodes concernant la determination de la largeur du profil intrinseque ({beta}) ont ete proposees. Dans le cas de l'oxyde de zinc on a montre la possibilite de differencier les contributions de l'effet de fragmentation et celui de perturbation du reseau, a l'effet total du broyage. Avec les deux varietes de sulfure de zinc (blende et Wurtzite) on a montre que le point de transformation de la blende en Wurtzite) etait fortement abaisse et que la transformation de la Wurtzite vers la forme stable (blende) a la temperature ambiante etait considerablement acceleree par le broyage. Dans le cas de l'antimoine le mode de fragmentation fait apparaitre une anisotropie qui doit etre reliee a l'existence des plans de clivage facile. Ces observations montrent que dans le cas d'un broyage effectue avec une energie suffisante, l'accumulation de cette energie dans la matiere par creation de defauts de reseau peut accelerer la vitesse de reaction ou provoquer des transformations physiques. (auteur)

Tekiz, Y. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-06-15

258

Evaluation of grinding methods for pellets preparation aiming at the analysis of plant materials by laser induced breakdown spectrometry.  

Science.gov (United States)

It has been demonstrated that laser induced breakdown spectrometry (LIBS) can be used as an alternative method for the determination of macro (P, K, Ca, Mg) and micronutrients (B, Fe, Cu, Mn, Zn) in pellets of plant materials. However, information is required regarding the sample preparation for plant analysis by LIBS. In this work, methods involving cryogenic grinding and planetary ball milling were evaluated for leaves comminution before pellets preparation. The particle sizes were associated to chemical sample properties such as fiber and cellulose contents, as well as to pellets porosity and density. The pellets were ablated at 30 different sites by applying 25 laser pulses per site (Nd:YAG@1064 nm, 5 ns, 10 Hz, 25J cm(-2)). The plasma emission collected by lenses was directed through an optical fiber towards a high resolution echelle spectrometer equipped with an ICCD. Delay time and integration time gate were fixed at 2.0 and 4.5 ?s, respectively. Experiments carried out with pellets of sugarcane, orange tree and soy leaves showed a significant effect of the plant species for choosing the most appropriate grinding conditions. By using ball milling with agate materials, 20 min grinding for orange tree and soy, and 60 min for sugarcane leaves led to particle size distributions generally lower than 75 ?m. Cryogenic grinding yielded similar particle size distributions after 10 min for orange tree, 20 min for soy and 30 min for sugarcane leaves. There was up to 50% emission signal enhancement on LIBS measurements for most elements by improving particle size distribution and consequently the pellet porosity. PMID:21872013

Gomes, Marcos da Silva; Santos, Dário; Nunes, Lidiane Cristina; de Carvalho, Gabriel Gustinelli Arantes; Leme, Flávio de Oliveira; Krug, Francisco José

2011-09-30

259

Investigations of spherical grinding parameters on circularity error, finished diameter, and grinding forces for porous polyurethane foam  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to examine the effect of grinding variables on the circularity error, finished diameter, andgrinding forces of porous polyurethane foam (PPUF. A cube of PPUF having the size of 21 mm was transformed into a roundshape using a vertical wheel grinding with the circular groove pad developed. The grinding speed (Vs of the wheel wasvaried between 1.41 and 5.18 m/s. The cross head speed of the circular groove pad (f was controlled at 1, 3, 5 mm/min. Theabrasive grit size (A of 20 and 53 ?m made of silicon carbide were applied. Two replications of experiment were randomlyperformed. Diameter and circularity error of the ground specimen were determined by vision measuring machine. The tangentialand normal forces of grinding were obtained using a dynamometer. The experimental data were statistically analyzed. The study found that (1 the grinding speed could remarkably affect the circularity error, finished diameter, and grinding forces,(2 the grinding speed ranged between 2.83 and 3.77 m/s could contribute to sphere shape specimens, and (3 the grinding speed of 3.30 m/s, cross head speed of 1 mm/min, and abrasive grit size of 20 ?m provided the least circularity error.

Isarawit Chaopanich

2010-07-01

260

Chirality Change by Grinding Crystals in Solution  

International Nuclear Information System (INIS)

One of the greatest unsolved problems in chemistry is the origin of homochirality in the biosphere, that is, the fact that l-amino acids and d-sugars dominate in biology, while laboratory experiments with stereoselective reactions only produce racemic mixtures. Several models have been proposed to address the question of how enantiomerically pure solutions or crystalline phases could have emerged from a presumably racemic prebiotic world. Here we show that two populations of amino acid crystals of 'left' and 'right' hand cannot coexist in solution: one of the chiral populations disappears in an irreversible autocatalytic process that nurtures the other one. Final and complete chiral purity seems to be an inexorable fate in our systems, under grinding, in the course of the common process of growth-dissolution. This unexpected chiral symmetry breaking has become firmly established but the underlying mechanism is being debated and we have no definitive answer.

 
 
 
 
261

Grinding Characteristics of Reaction Bonded Silicon Carbide  

Directory of Open Access Journals (Sweden)

Full Text Available Surface topography, surface residual stress and bending strength of RBSiC ground using diamond wheel were studied. Grinding RBSiC is removed mainly by brittle fracture and lightly by ductile cutting. With the increase of down feed, surface roughness Ra increases. Burnishing with no down feed can improve the Ra in some way. With increasing down feed, the compressive residual stress decreases because of an inadequately cooling effect. Compare with the specimens grounded using 0.9 ?m/s, those using down feed of 1.35 ?m/s have worse surface quality. Considering both the processing efficiency and the surface quality, the optimum parameters are as follow: 0.9?m/s down feed, 2.1 r/min work table rotational speed and 1 min burnishing.

YAO Wang, ZHANG Yu-Min, HAN Jie-Cai, ZHOU Yu-Feng

2012-07-01

262

The Grinding Wheel Performance in the Transverse Cylindrical Grinding of an Eutetic Alloy  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a research in which the performance of two different grinding wheels (a conventional and a CBN wheel was evaluated in a transverse cylindrical grinding of a eutectic alloy. Three cutting conditions were tested: rough, semi-finishing and finishing. As evaluating parameters, the cutting force, the roughness and the wheel wear were measured. As a result, the best values of the cutting force and the roughness were obtained when grinding with the conventional wheel, due to the best dressing operation performed, for all the cutting conditions. The CBN presented the best G ratio values. Although, the G ratio values observed for the CBN wheel were lower than the expected one due to the non-effective dressing operation applied. In the conditions tested, in terms of cutting force and roughness, the conventional wheel is the best choice. In terms of G ratio, a cost analysis is crucial to determine if the differences observed among the wheels can justify the use of the CBN wheel. In a positive case, the dressing operation must be improved.

Eduardo Carlos Bianchi

2002-10-01

263

The Grinding Wheel Performance in the Transverse Cylindrical Grinding of an Eutetic Alloy  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english This paper presents a research in which the performance of two different grinding wheels (a conventional and a CBN wheel) was evaluated in a transverse cylindrical grinding of a eutectic alloy. Three cutting conditions were tested: rough, semi-finishing and finishing. As evaluating parameters, the c [...] utting force, the roughness and the wheel wear were measured. As a result, the best values of the cutting force and the roughness were obtained when grinding with the conventional wheel, due to the best dressing operation performed, for all the cutting conditions. The CBN presented the best G ratio values. Although, the G ratio values observed for the CBN wheel were lower than the expected one due to the non-effective dressing operation applied. In the conditions tested, in terms of cutting force and roughness, the conventional wheel is the best choice. In terms of G ratio, a cost analysis is crucial to determine if the differences observed among the wheels can justify the use of the CBN wheel. In a positive case, the dressing operation must be improved.

Eduardo Carlos, Bianchi; Eraldo Jannone da, Silva; Vinicio Lucas, Vargas; Thiago Cardoso, Magagnin; Rodrigo Daun, Monici; Osmar, Vicari Filho; Paulo Roberto de, Aguiar.

264

Development of a modified grind-leach process for processing Triso-coated reactor fuel  

International Nuclear Information System (INIS)

An advanced or modified grind-leach process has been under development as a head-end treatment to separate the fuel components from spent tri-structural-isotropic (TRISO)-coated fuel and to prepare the fuel for separations in a standard aqueous processing plant. Conceptually, the process involves removing the fuel compacts from the graphite fuel element, grinding the compacts to expose the fuel kernel, optionally separating the lighter carbon particles from the heaver fuel particles and leaching or dissolving the fuel components from the remaining carbon and silicon carbide fines. The nitric acid leaching step may be directly interfaced with conventional aqueous solvent extraction processes. The finely divided carbon waste may be reformed into a compact and durable waste form. Laboratory studies of the key process steps have been performed using surrogates because irradiated fuels were not available. The fuel compacts may be removed from the graphite block to eliminate nearly all the block-graphite and thus the primary source of organic by-products in the leaching step. Tests have been recently completed to study the milling process. Using commercially available laboratory-scale jet mills, tests with surrogate fuel particles, including TRISO-coated zirconia and hafnia, showed that the friable coatings could be stripped from the relatively tough kernels. The coating fragments were very small, whereas the kernel fragments were larger. Similar results were obtained with unirradiated coated urania kernels. Because the coating layers were milled to very small particle sizes, it was anticipated that acids would have good access to the fuel components. This mitigates losses of fuel materials embedded in the coatings. With the coatings breached or removed, the kernels would tend to dissolve completely. These tests strongly indicate that jet milling produces a product conducive to acid leaching. Proof-of-principle tests using simulated crushed TRISO-coated fuel have indicated little, if any, production of soluble organic species in the leaching process. Nitric acid leaching of milled surrogate TRISO-coated fuel followed by filtering produced a clear yellow solution. This solution was used in shake-out tests with uranium extraction solvent (tri-n-butyl phosphate in n-dodecane diluent). No physical process problems such as foaming, formation of emulsions, or failure to achieve clean phase separation were observed. Negligible effects on the solvent extraction process were evidenced by measured distribution ratios close to expected values. These initial studies indicate that the modified crush-leach process is suitable for processing of TRISO-coated fuels. Further studies using irradiated fuels are recommended. Processes to fabricate a carbon waste form should also be tested. (authors)

265

Multi-field coupled numerical simulation of hot reversible rolling process of GCr15 steel rod  

Science.gov (United States)

In this paper, based on rolling technology of hot reversible rolling mill, a multi-filed coupled finite element (FE) model of hot reversible rolling process of large dimension cross-section GCr15 steel rod is established. Thermal, mechanical and microstructural phenomena during the rolling process are coupled in the model. By employing grain growth experiment, double and single hit hot compression experiments, the austenite grain size growth mathematical model and recrystallization behavior mathematical models are determined. And a designed subprogram is coupled in the FE model. Actual hot reversible rolling process of GCr15 steel is simulated using the model and the distribution and evolution of different filed-variables, such as temperature, effective strain and austenite grain size are obtained. To verify the model predictions, hot rolling experiments are carried out and the temperature and microstructure of the rolling metal are compared with the predicted results. The comparison between the two sets of data shows a good agreement.

Gu, Sendong; Zhang, Liwen; Ruan, Jinhua; Mei, Hongyu; Zhen, Yu; Shi, Xinhua

2013-05-01

266

Fabrication experience and evaluation of high energy ball mill for glove boxes  

International Nuclear Information System (INIS)

A compact high energy ball mill was developed for quick and efficient milling of ceramic oxide powders inside glove boxes. This paper presents the salient features of this equipment developed and indigenously procured. Manual handling of jars and radioactive powders could be considerably reduced by use of this equipment compared with conventional jar milled at present deployed for this purpose. Large quantities of ThO2 powder have been milled in this equipment and sintered to high densities. A study of the efficiency of the machine in milling of powders has been conducted. The powder characteristics such as particle size, distribution and surface area of the powders milled in this equipment are also presented in this paper. The variation in these characteristics with time, speed and ratio of charge to grinding media has been studied and compared with those of conventional ball mill. (author)

267

Development of Roller Ends Forced-Contact Model and Cambering Technology for UCM Temper Mill (II——Development of cambering technology for UCM temper mill  

Directory of Open Access Journals (Sweden)

Full Text Available Roller ends forced-contact and overmuch roll consumption are the widespread problems in temper rolling process of thin strip for two-stand UCM temper mill. Fully thinking the equipment and technology characteristics of UCM temper mill, we took the newly-built 1220 UCM temper mill of Baosteel as the research object in this paper. A model of roller ends forced-contact and a calculation model of flatness for UCM temper mill are established after a great deal of site tracing and theoretical researches. On this basis, an optimal mathematical model of roll shape which is suited for UCM temper mill is developed. Working roll curve is the combination of cosine curve and high order curve. The cosine subentry is used to control edge wave, the high order curve subentry is used to control roller ends forced-contact. Furthermore, the chamfering curve of middle roller end is optimized. Those are the innovations. Through the above-mentioned technology, pressure distribution between rollers caused by the shift of middle roll becomes more homogeneous, pressure peak disappeared, working life of roll is improved effectively as well. Relevant technologies have been used to the practice of 1220 UCM temper mill of Baosteel and have achieved good use effects, which is of further extending application value.

Zhenhua Bai

2011-07-01

268

Peat milling  

...dominant technique for large-scale peat extraction across Europe. Peat milling is unsustainable, destroying the...a harrow to assist the drying process. When the peat is dry enough, it is...supply plants grown in 'reduced peat' or peat free media....

269

Ultraprecision, high stiffness CNC grinding machines for ductile mode grinding of brittle materials  

Science.gov (United States)

Under certain controlled conditions it is now possible to machine brittle materials such as glasses and ceramics using single or multi-point diamond tools (grinding), so that material is removed by plastic flow, leaving crack-free surfaces. This process is called 'shear' or 'ductile' mode grinding. It represents a major breakthrough in modern manufacturing engineering since it promises to enable: - complex optical components, both transmission and reflecting to be generated by advanced CNC machines with very little (or even zero) subsequent polishing. - complex shaped components such as turbine blades, nozzle guide vanes, etc. to be finish machined after near net shape forming, to high precision in advanced ceramics such as silicon nitride, without inducing micro-cracking and thus lowering ultimate rupture strength and fatigue life. Ductile mode "damage free" grinding occurs when the volume of materials stressed by each grit of the grinding wheel is small enough to yield rather than exhibit brittle fracture, i.e. cracking. In practice, this means maintaining the undeformed chip thickness to below the ductile-brittle transition value; this varies from material to material but is generally in the order of 0.1 pm or 100 nm, (hence the term "nanogrinding" is sometimes used) . Thus the critical factors for operating successfully in the ductile regime are machine system accuracy and dynamic stiffness between each grit and the workpiece. In detail this means: (i) High precision 'truing' of the diamond grits, together with dressing of the wheel bond to ensure adequate ' openness'; (ii) Design and build of the grinding wheel spindle with very high dynamic stiffness; error motions, radial and axial, must be considerably less than 100 nfl. (iii) Design and build of the workpiece carriage motion system with very high dynamic stiffness; error motions, linear or rotary, must be well within 100 nm. (iv) Smooth, rumble-free, high-stiffness servo-drives controlling the motions which form the chip. In general, and as a rule of thumb, a machine "loop-stiffness" (between tool and workpiece) not less than 300 N,4im (static) is necessary.

McKeown, Patrick A.; Carlisle, Keith; Shore, Paul; Read, R. F.

1990-10-01

270

Modeling and Optimization of Face Milling Operation Based on Response Surface Methodology and Genetic Algorithm  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Materials are manufactured from casting, forging and extrusion processes have higher typical dimension tolerences due to its producing ability. So machining processes were introduced for close tolerence asssembly and improve the product working efficiencies. In response, now a day’s lot of machining processes are available such as turning, milling, drilling and grinding to overcome these problems. Milling operation is playing vital role on making the components with high accuracy and highe...

Kannan. S; Baskar. N

2013-01-01

271

Hybrid Hot Strip Rolling Force Prediction using a Bayesian Trained Artificial Neural Network and Analytical Models  

Directory of Open Access Journals (Sweden)

Full Text Available The authors discuss the combination of an Artificial Neural Network (ANN with analytical models to improve the performance of the prediction model of finishing rolling force in hot strip rolling mill process. The suggested model was implemented using Bayesian Evidence based training algorithm. It was found that the Bayesian Evidence based approach provided a superior and smoother fit to the real rolling mill data. Completely independent set of real rolling data were used to evaluate the capacity of the fitted ANN model to predict the unseen regions of data. As a result, test rolls obtained by the suggested hybrid model have shown high prediction quality comparatively to the usual empirical prediction models.

Abdelkrim Moussaoui

2006-01-01

272

Parametric Roll Instability of Ships  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Parametric roll may be defined as the spontaneous rolling motion of the ship moving in head or following seas that comes about as a result of the dynamic instability of motion. The development of the parametric roll occurs under the conditions that the encounter angular frequency is approximately twice the roll angular frequency, the wavelength is equal to the ship length and the roll damping is insufficient to dissipate the parametric roll energy. In this Thesis t...

Sheikh, Irfan Ahmad

2008-01-01

273

Adaptive Automatic Gauge Control of a Cold Strip Rolling Process  

Directory of Open Access Journals (Sweden)

Full Text Available The paper tackles with thickness control structure of the cold rolled strips. This structure is based on the rolls position control of a reversible quarto rolling mill. The main feature of the system proposed in the paper consists in the compensation of the errors introduced by the deficient dynamics of the hydraulic servo-system used for the rolls positioning, by means of a dynamic compensator that approximates the inverse system of the servo-system. Because the servo-system is considered variant over time, an on-line identification of the servo-system and parameter adapting of the compensator are achieved. The results obtained by numerical simulation are presented together with the data taken from real process. These results illustrate the efficiency of the proposed solutions.

ROMAN, N.

2010-02-01

274

Thermomechanical Behavior of Work Rolls During Warm Strip Rolling  

Science.gov (United States)

A mathematical model was developed to assess thermomechanical behavior of work rolls during warm rolling processes. A combined finite element analysis-slab method was first developed to determine thermal and mechanical responses of the strip being rolled under steady-state conditions, and then, the calculated roll pressure and temperature field were utilized as the governing boundary conditions for the thermomechanical problem of the work roll. Finally, the thermomechanical stresses within the work rolls were predicted by a thermoelastic finite element approach. The results of the model indicate that, in warm strip rolling, thermal and mechanical stresses developed in the work rolls are comparable, and thus, both thermal and mechanical aspects of the problem should be considered in such a problem. Besides, the model was shown to be capable of determining the effects of various rolling parameters on the thermomechanical behavior of the work rolls during warm rolling process.

Khalili, L.; Serajzadeh, S.; Koohbor, B.

2012-12-01

275

McCarter superfinish grinding for silicon -- an update.  

Energy Technology Data Exchange (ETDEWEB)

A grinding technique, referred to as the McCarter Superfinish, for grinding large size optical components is discussed and certain surface characterization information about flatness and the relative magnitude of the subsurface damage in silicon substrates is reported. The flatness measurements were obtained with a Zygo surface analyzer, and the substrate damage measurements were made by x-ray diffraction and acid etching. Results indicate excellent control of flatness and fine surface finish. X-ray measurements show that the diamond wheels with small particle sizes used in the final phases of the grinding operation renders surfaces with relatively small subsurface damage.

Anthony, F.; Khounsary, A.; McCarter, D.; Krasnicki, F.; Tangedahl, M.

2000-11-03

276

Numerical analysis of small recessed silicon carbide grinding wheels  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Silicon carbide grinding wheels are tools used in manufacturing industry to form precision componentsand continue to be used to increase production rates due to their ability to remove high volumes of material athigh speeds. There is a demand to increase the speed of rotation of the grinding wheel in order to achieve highremoval rates. The increase in speed creates a situation where the grinding machine and the operator are subjectedto a possible catastrophic failure of the wheel due to the stresses generated in the coarse brittle structure of thevitrified grinding wheel. The study focused on building and analyzing computer models of grinding wheels withrecessed features spinning at different rotational speeds. By employing a computational approach, it was possibleto determine the maximum principal stresses in the wheel together with the location of the stresses. The geometryof vitrified wheels considered included a plain-sided rotating wheel and a recessed rotating wheel.Design/methodology/approach: The paper shows how stresses and factors of safety are calculated in order topredict the bursting speeds of small recessed SiC grinding wheels. The main methods used include finite elementanalysis and mechanical testing of abrasive materials. The approach of the paper is to integrate the use of numericalanalysis techniques and experimental techniques to predict the safe operating conditions of SiC abrasive products.Findings: Calculations were conducted to determine maximum stress in parallel-sided and recessed cup wheels.Relevant factors of safety and bursting speed were also calculated and compared with experimental data. Thepaper proves the usefulness and applicability of a method developed for taking account of stress concentrationsat the recess of small cup-shaped silicon carbide grinding wheels.Research limitations/implications: The paper is limited to analyzing small recessed SiC grinding wheels.Further work should focus on large recessed wheels and wheels made with different abrasive grains and bondingmaterials. The type of porosity distribution should also be investigated.Practical implications: The paper shows how numerical methods are used to design safe operating conditionsfor brittle grinding wheels. The methods used show that numerical techniques are suitable for calculating themeasures of safety that are an important consideration when designing high speed rotating grinding wheels thatcan be devastating if allowed to fail in service.Originality/value: The originality in the paper is revealed owing to the fact that fracture mechanics principlesare applied to the prediction of failure of rotating grinding wheels. The paper is of practical importance tomechanical designers who are responsible for the safe design of grinding wheels.

M.J. Jackson

2010-11-01

277

Production of scallop shell nanoparticles by mechanical grinding as a formaldehyde adsorbent  

International Nuclear Information System (INIS)

Scallop shells, which are a waste product in the seafood industry, are disposed more than 200,000 ton per year in Hokkaido, Japan. We report effective uses and simple application for discarded shells as a formaldehyde adsorbent. The adsorption performance of scallop shells to remove formaldehyde vapor is investigated. Planetary ball milling under dry conditions and subsequent water addition realize shells with a crystallite size (35–90 nm) and equivalent size of the specific surface area (41–191 nm) in the nanometer range. The comminution properties of the scallop shells, especially the grinding limit, are estimated via a semi-theoretical consideration for the grinding limit. Additionally, the adsorbed amount of gaseous formaldehyde using a self-designed adsorption line is estimated. The nanosized scallop shells exhibit an excellent adsorption performance rather than the feed shell, and the adsorbed amount is positively correlated with the specific surface area of the shell. Hence, scallop shells have potential to adsorb volatile organic compounds.

278

Properties of nano-structured pure Al produced by mechanical grinding and spark plasma sintering  

International Nuclear Information System (INIS)

Air-atomised pure aluminium powder was mechanically grinded (MG) using a vibrational ball mill, and mechanically grinded powder was sintered by spark plasma sintering (SPS). Solid-state reactions of MG powder after various heat treatments were studied by X-ray diffraction (XRD). The mechanical properties of the SPS materials were evaluated by hardness and compression testing. Characterisations of the solid-state reactions between the MG powder and process control agent (PCA) after heating at temperatures from 573 to 873 K for 24 h suggested the following products. No solid-state reaction was observed after heating up to 573 K for 24 h. Formation of ?-Al2O3 occurred in the 4 h MG powder after heating at 773 K for 24 h, whereas the mixture of ?-Al2O3 and Al4C3 was observed in the 8 h MG powder after heating at 773 K for 24 h. The full density of the SPS material was obtained with the condition of applied pressure at 49 MPa at 873 K for 1 h. The Vickers hardness of the SPS material produced from no MG process and 64 h MG powders exhibited HV39 and HV159, respectively, and the SPS material based on no MG process and 8 h MG powders showed room temperature compressive proof stresses of 173 and 440 MPa, respectively

279

The effects of the fine grinding on the physicochemical properties and thermal behavior of bentonite clay  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, the results obtained by the mechanical treatment of bentonite clay Zavidinci, Serbia in a laboratory vibration mill with rings for different periods of time are presented. The successive structural changes of the minerals were studied by X-ray diffraction analysis, DTA analysis, IR spectroscopy and particle size distribution. The reactivity changes were controlled by CEC. The starting material and the material mechanically treated for 30 min were sintered at several temperature and for different time periods examined by X-ray diffraction. Mechanical treatment by fine grinding of bentonite clay produces structural changes of the powdered material and influences its behavior in further processing steps in particular after thermal treatment.

STANKA ERIC-ANTONI

2002-11-01

280

Absence of evidence of decomposition of Fe2B during mechanical grinding  

International Nuclear Information System (INIS)

The appearance of bcc Fe after grinding Fe2B for a long time has been formerly interpreted as being due to the decomposition of the thermodynamically stable intermetallic compound when the crystallite size is reduced to a few nanometers. The results of our control experiments performed by tungsten-carbide milling tools show that the appearance of bcc Fe has no relation to the grain size but should be connected to contamination when tools made of steel are used to pulverize this material. Moessbauer spectroscopy was applied to search for the appearance of bcc Fe while changes in the grain size were checked by x-ray diffraction and transmission electron microscopy. copyright 1998 The American Physical Society

 
 
 
 
281

Validation of the Hot Strip Mill Model  

Energy Technology Data Exchange (ETDEWEB)

The Hot Strip Mill Model (HSMM) is an off-line, PC based software originally developed by the University of British Columbia (UBC) and the National Institute of Standards and Technology (NIST) under the AISI/DOE Advanced Process Control Program. The HSMM was developed to predict the temperatures, deformations, microstructure evolution and mechanical properties of steel strip or plate rolled in a hot mill. INTEG process group inc. undertook the current task of enhancing and validating the technology. With the support of 5 North American steel producers, INTEG process group tested and validated the model using actual operating data from the steel plants and enhanced the model to improve prediction results.

Richard Shulkosky; David Rosberg; Jerrud Chapman

2005-03-30

282

Roll force prediction of high strength steel using foil rolling theory in cold skin pass rolling  

Energy Technology Data Exchange (ETDEWEB)

Skin pass rolling is a very important process for applying a certain elongation to a strip in the cold rolling and annealing processes, which play an important role in preventing the stretching of the yield point when the material is processed. The exact prediction of the rolling force is essential for obtaining a given elongation with the steel grade and strip size. Unlike hot rolling and cold rolling, skin pass rolling is used to apply an elongation of within 2% to the strip. Under a small reduction, it is difficult to predict the rolling force because the elastic deformation behavior of the rolls is complicated and a model for predicting the rolling force has not yet been established. Nevertheless, the exact prediction of the rolling force in skin pass rolling has gained increasing importance in recent times with the rapid development of high strength steels for use in automobiles. In this study, the possibility of predicting the rolling force in skin pass rolling for producing various steel grades was examined using foil rolling theory, which is known to have similar elastic deformation behavior of rolls in the roll bite. It was found that a noncircular arc model is more accurate than a circular model in predicting the roll force of high strength steel below TS 980 MPa in skin pass rolling.

Song, Gil Ho; Jung, Jae Chook [Rolling and Measurement Research Group of Posco Technical Research Laboratory, Pohang (Korea, Republic of)

2013-02-15

283

7.SP Rolling Dice  

Science.gov (United States)

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Roll two dice 10 times. After each roll, note whether any sixes were observed and record your results in the table below. RollAny Sixes?(Y/N) 1 2 3 4 5...

284

Surface topography of parallel grinding process for nonaxisymmetric aspheric lens  

International Nuclear Information System (INIS)

Workpiece surface profile, texture and roughness can be predicted by modeling the topography of wheel surface and modeling kinematics of grinding process, which compose an important part of precision grinding process theory. Parallel grinding technology is an important method for nonaxisymmetric aspheric lens machining, but there is few report on relevant simulation. In this paper, a simulation method based on parallel grinding for precision machining of aspheric lens is proposed. The method combines modeling the random surface of wheel and modeling the single grain track based on arc wheel contact points. Then, a mathematical algorithm for surface topography is proposed and applied in conditions of different machining parameters. The consistence between the results of simulation and test proves that the algorithm is correct and efficient. (authors)

285

A critical study of high efficiency deep grinding  

CERN Document Server

The recent years, the aerospace industry in particular has embraced and actively pursued the development of stronger high performance materials, namely nickel based superalloys and hardwearing steels. This has resulted in a need for a more efficient method of machining, and this need was answered with the advent of High Efficiency Deep Grinding (HEDG). This relatively new process using Cubic Boron Nitride (CBN) electroplated grinding wheels has been investigated through experimental and theoretical means applied to two widely used materials, M50 bearing steel and IN718 nickel based superalloy. It has been shown that this grinding method using a stiff grinding centre such as the Edgetek 5-axis machine is a viable process. Using a number of experimental designs, produced results which were analysed using a variety of methods including visual assessment, sub-surface microscopy and surface analysis using a Scanning Electron Microscope (SEM), residual stress measurement using X-Ray Diffraction (XRD) techniques, Ba...

Johnstone, I

2002-01-01

286

Understanding of Ultrasonic Assisted Machining with Diamond Grinding Tool  

Directory of Open Access Journals (Sweden)

Full Text Available In this work, machining test was carried out in various machining conditions using ultrasonic vibration capable CNC machine. For work material, alumina ceramic (Al2O3 was used while for tool material diamond electroplated grinding wheel was used. To evaluate ultrasonic vibration effect, grinding test was performed with and without ultrasonic vibration in same machining condition. In ultrasonic mode, ultrasonic vibration of 20 kHz was generated by HSK 63 ultrasonic actuator. On the other hand, grinding forces were measured by KISTLER dynamometer. And an optimal sampling rate for grinding force measurement was obtained by a signal processing and frequency analysis. The surface roughness of the ceramic was also measured by using stylus type surface roughness instrument and atomic force microscope (AFM. Besides, the scanning electron microscope (SEM was used for observation of surface integrality.

Kyung-Hee Park

2013-12-01

287

Sludge minimization achieved through grinding and reaeration  

International Nuclear Information System (INIS)

A parallel, bench-scale study was undertaken to study the effect of grinding/blending biological solids followed by subsequent aeration for 24-hours on overall sludge production. This was compared to a completely-mixed system from which solids were wasted directly back to the aeration basin. In essence, both treatment trains employed total recycle of the waste biological solids, except that the solids from Train 2 were ground and aerated prior to re-introduction. The bench-scale reactors were continuously operated from November through December 2000 and from January through April 2001. Temperature of the wastewater during the first and second runs was maintained at 14o C and 25o C, respectively. Each parallel train was fed synthetic wastewater at a flow rate of approximately 2.25 gallons per day resulting in a hydraulic detention time of approximately 13 hours. Samples of the influent, effluent, and mixed liquor were collected weekly and the following analyses were performed: COD, pH, temperature, total solids, suspended solids, volatile suspended solids, dissolved solids, and oxygen uptake rate (OUR). Results of the study indicate that the system in which the solids were ground and re-aerated produced less sludge than the conventional system. Substrate removal rates were the same for both systems. Statistical analyses using the analysis of variance indicated the results were significant at the 95 % confidence level. (author)dence level. (author)

288

CISM Course on Rolling Contact Phenomena  

CERN Document Server

Preface.- Rolling Contact Phenomena - Linear Elasticity.- Finite Element Methods for Rolling Contact.- Plastic Deformation in Rolling Contact.- Non-Steady State Rolling Contact and Corrugations.- Modelling of Tyre Force and Moment Generation.- Rolling Noise.- Lubrication

Kalker, Joost

2000-01-01

289

In-Orbit Construction with a Helical Seam Pipe Mill  

Science.gov (United States)

The challenges of building large structures in space, and in particular a torus habitat, require novel processes. One potential method is to manufacture helical seam (also called spiral) pipe in orbit using a pipe mill. These machines turn rolls of steel or alloy into fully formed, welded and inspected pipe, pressure vessels and silos of various diameters. Pipe mills are highly automated and efficient in a factory environment and are increasingly being used for in-situ repair. By constructing in-orbit (on-orbit assembly) the launch vehicle can supply full payloads of compact, robust rolls of material; and the installation design is less restricted by fairing constraints and modular limitations. The use of a pipe mill is discussed as a possible construction method, for comparison an example design envelope is shown and further pipe mill products are considered.

Gilhooley, N.

290

Innovative grinding wheel design for cost-effective machining of advanced ceramics  

Energy Technology Data Exchange (ETDEWEB)

This Final Report covers the Phase II Innovative Grinding Wheel (IGW) program in which Norton Company successfully developed a novel grinding wheel for cost-effective cylindrical grinding of advanced ceramics. In 1995, Norton Company successfully completed the 16-month Phase I technical effort to define requirements, design, develop, and evaluate a next-generation grinding wheel for cost-effective cylindrical grinding of advanced ceramics using small prototype wheels. The Phase II program was initiated to scale-up the new superabrasive wheel specification to larger diameters, 305-mm to 406-mm, required for most production grinding of cylindrical ceramic parts, and to perform in-house and independent validation grinding tests.

Licht, R.H.; Kuo, P.; Liu, S.; Murphy, D.; Picone, J.W.; Ramanath, S.

2000-05-01

291

Environmental Impact of Electricity Consumption in Crushing and Grinding Processes of Traditional and Urban Gold Mining by Using Life Cycle Assessment (LCA  

Directory of Open Access Journals (Sweden)

Full Text Available Mining is not only an essential component of social and economic development since prehistoric time, but it also gives a large impact on our civilization. Gold is a noble metal that is highly valued. The extraction of minerals from earth is known as traditional mining. Gold also can be extracted from electronic waste or e-waste, and this new concept is called urban mining. There are many stages in traditional and urban mining process. However, in this study, the focus was on crushing and grinding processes to produce 1 kg of gold. Crushing and grinding are processes in the milling stage. This research evaluates and compares the environmental impacts of crushing and grinding processes, based on electricity consumption. About 50 to 65% of total electricity in milling was used for crushing and grinding processes. Life Cycle Assessment (LCA methodology was used as a tool to evaluate the environmental burdens of electricity usage in converting ore and electronic waste to gold bars. The Life Cycle Impact Assessment (LCIA of this process was interpreted by using Eco-indicator 99 assessment methods in SimaPro software. The impact categories included in this study were carcinogens, respiratory organics, respiratory inorganics, radiation, climate change, ozone layer, ecotoxicity, acidification or eutrophication, land use and minerals. The results showed that crushing and grinding from traditional mining gave the largest impact to the environment with single score of 399 Pt compared to the urban mining with only 1.81 Pt score. The highest impact in both types of mining is to human health.

Nur Rafidah Yahaya

2012-01-01

292

Quadropol RD. The world's first vertical roller mill with driven rollers; Quadropol RD. Weltweit erste Vertikalrollenmuehle mit angetriebenen Rollen  

Energy Technology Data Exchange (ETDEWEB)

The cement industry increasingly requires energy-efficient grinding systems for the production of ultra-fine cements. The vertical mill with driven rollers meets this requirement thanks to the innovative design of its drive system. Although no CO{sub 2} emissions are released in the mill itself, the mill contributes to reducing specific CO{sub 2} emissions in the production of ultra-fine composite cements. (orig.)

Schmitz, Thomas [ThyssenKrupp Resource Technologies GmbH, Neubeckum (Germany). Enginering Cement Production; Berger, Markus [ThyssenKrupp Resource Technologies GmbH, Neubeckum (Germany). R and D Automation; Fornefeld, Heiko [ThyssenKrupp Resource Technologies GmbH, Neubeckum (Germany). Engineering Design Roller Mills; Kimmeyer, Ludger [ThyssenKrupp Resource Technologies GmbH, Neubeckum (Germany). R and D Communication Technology

2013-11-01

293

Influence of different grinding processes on residual stress  

International Nuclear Information System (INIS)

This investigation was made in order to find out a distribution of residual stress on the surfaces ground under various grinding conditions obtained by changing an actual depth of cut, number of grinding and a grinding process under a constant state of a chip cross sectional area. The surfaces of the specimens were ground by only up cut, only down cut and both up and down cut, respectively. The experimental data were analyzed by using both the Doelle-Hauk method and the integral method which takes into account of the stress gradient. As a result, the residual stress on the surface of one pass grinding showed higher tensile stress when a larger actual depth of cut took place. And the residual stress of down cut grinding was higher than that of up cut. By repeating another re-grinding on the same surface, the residual stress translated into a compressive stress and then converged into a certain level. On the contrary, the stress gradient changed to positive side in such case. (author)

294

Grinding aspheric and freeform micro-optical molds  

Science.gov (United States)

Fueled by the need for better performing optics, glass optics are now replacing plastic optics in many industrial and consumer electronic devices. One of these devices is the mobile phone camera. The optical sub-assembly in a mobile phone includes several micro lenses that are spherical and/or aspherical in shape and require form tolerances in the submicron range. These micro glass lenses are mass produced by a replication process known as glass press molding. The process entails the compression of a glass gob between two precise optical quality molds at an elevated temperature, usually near the transition temperature of the glass material. The elevated forces and temperatures required in the glass molding process limits the materials of the molds to very tough materials such as tungsten carbide or silicon carbide. These materials can withstand large pressing forces at high temperatures without any significant deformation. These materials offer great mechanical properties for glass press molding but they are also a challenge to machine to submicron accuracy. The work in this paper discusses a deterministic micro grinding manufacturing process referred to as wheel normal grinding, which is utilized to produce these optical quality molds. Wheel normal grinding is more accurate and more deterministic than most other grinding techniques and can produce molds to the form and finish tolerances required for optical molding. This method relies on the ability to recognize and compensate for grinding wheel wear and machine repeatable errors. Results will be presented to illustrate the accuracy of this micro grinding technique.

Tohme, Yazid E.

2007-02-01

295

Grooved roll for a high speed twin roll caster  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Purpose of this paper is investigation of the effect of roll-surface on the strip-surface. Improvement ofsmall cracks on the strip-surface was tried and effect of groove at the roll surface on the strip surface was shown.Design/methodology/approach: Method used in the present study was high speed twin roll caster withgrooved roll. Two kinds of grooves were used: one was parallel groove and the other was cross groove machinedby knurling and bite attached to a lathe.Findings: Findings of this research are that grooved roll was effective to eliminate the small cracks on the stripsurface. The contact condition between the roll and the melt became uniform by the small groove on the rollsurface. Contact area became small, and heat transfer between the melt and roll became small, too. As the result,chill structure did not become columnar, and crack did not occur. Groove pattern on the strip surface could beerased by the cold rolling.Research limitations/implications: Research limitation is that groove life could not be investigated.Practical implications: Practical implications are as below. The roll load was small and strip was not hot-rolledin a high speed twin roll caster. The grooved roll made strip-surface sound. Grooved 600mm width roll was tested,and usefulness of the grooved roll was shown.Originality/value: In the present study effect of the grooved roll on a high speed twin roll caster was investigated.

T. Haga

2008-04-01

296

Rolling Shutter Stereo  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A huge fraction of cameras used nowadays is based on CMOS sensors with a rolling shutter that exposes the image line by line. For dynamic scenes/cameras this introduces undesired effects like stretch, shear and wobble. It has been shown earlier that rotational shake induced rolling shutter effects in hand-held cell phone capture can be compensated based on an estimate of the camera rotation. In contrast, we analyse the case of significant camera motion, e.g. where a by...

Saurer, O.; Ko?ser, Kevin; Bouguet, J. -y; Pollefeys, M.

2013-01-01

297

IMPROVING ENERGY EFFICIENCY VIA OPTIMIZED CHARGE MOTION AND SLURRY FLOW IN PLANT SCALE SAG MILLS  

Energy Technology Data Exchange (ETDEWEB)

The U.S. mining industry operates approximately 80 semi-autogenesis grinding mills (SAG) throughout the United States. Depending on the mill size the SAG mills draws between 2 MW and 17 MW. The product from the SAG mill is further reduced in size using pebble crushers and ball mills. Hence, typical gold or copper ore requires between 2.0 and 7.5 kWh per ton of energy to reduce the particle size. Considering a typical mining operation processes 10,000 to 100,000 tons per day the energy expenditure in grinding is 50 percent of the cost of production of the metal. A research team from the University of Utah is working to make inroads into saving energy in these SAG mills. In 2003, Industries of the Future Program of the Department of Energy tasked the University of Utah team to build a partnership between the University and the mining industry for the specific purpose of reducing energy consumption in SAG mills. A partnership was formed with Cortez Gold Mines, Kennecott Utah Copper Corporation, Process Engineering Resources Inc. and others. In the current project, Cortez Gold Mines played a key role in facilitating the 26-ft SAG mill at Cortez as a test mill for this study. According to plant personnel, there were a number of unscheduled shut downs to repair broken liners and the mill throughput fluctuated depending on ore type. The University team had two softwares, Millsoft and FlowMod to tackle the problem. Millsoft is capable of simulating the motion of charge in the mill. FlowMod calculates the slurry flow through the grate and pulp lifters. Based on this data the two models were fine-tuned to fit the Cortez SAG will. In the summer of 2004 a new design of shell lifters were presented to Cortez and in September 2004 these lifters were installed in the SAG mill. By December 2004 Cortez Mines realized that the SAG mill is drawing approximately 236-kW less power than before while maintaining the same level of production. In the first month there was extreme cycling and operators had to learn more. Now the power consumption is 0.3-1.3 kWh/ton lower than before. The actual SAG mill power draw is 230-370 kW lower. Mill runs 1 rpm lesser in speed on the average. The re-circulation to the cone crusher is reduced by 1-10%, which means more efficient grinding of critical size material is taking place in the mill. All of the savings have resulted in reduction of operating cost be about $0.023-$0.048/ ton.

Raj K. Rajamani; Sanjeeva Latchireddi; Sravan K. Prathy; Trilokyanath Patra

2005-12-01

298

The Ball Mill Driving Device Fault and the Main Bearing Lubrication Analysis  

Directory of Open Access Journals (Sweden)

Full Text Available This article from the analysis of the power consumption of the ball mill and the work characteristic of the motor, analyzes the fault reason of ball mill transmission equipment. The paper mainly deals with a side-transmission ball mill. The main fault is about the breakdown in the elastic rubber coupling of the transmission system. It is found from the analysis of the real cases and data that the actual power consumption is increased and it is caused by the overload. The main parameters which influence the ball mill power consumption are load of the mill, feed material mass, ball mill rotational speed and friction. The main part of power consumption for ball mill is used to elevating grinding body and material, a portion is used to overcome the friction force between the main bearing. Under the conditions in which the load of the mill and feed material mass are kept the same, the parameters which influence the ball mill power consumption are rotational speed and friction status. When the ball mill voltage decreased, according to the motor characteristics, its rotation speed will decrease, which will disrupt the hydrodynamic lubrication state of the hollow shaft and spherical surface, so that the power consumption of the ball mill increase. The larger power leads to the transmission fault. This paper also put forward to make sure kept the ball mill main bearing lubrication status.

Tong Junfeng

2013-04-01

299

Vibration analysis of rail grinding using a twin-wheel grinder  

Science.gov (United States)

Grinding is the final process of machining a rail. Conventionally, the rail's surfaces are ground by a single-wheel grinder. The vibrations caused by the grinding process can greatly influence the final surface roughness and dimensional accuracy of the rail. This research investigates performance achieved by using two grinding wheels simultaneously and symmetrically on two opposite surfaces of a rail. In practical terms, the feed force from the two grinding wheels cannot be aligned perfectly, and the imbalance and/or imperfect roundness of the grinding wheels will certainly result in vibrations during the grinding process. This study applies an impedance method to determine rail vibration and the grinding instability, such as chatter caused by feed force misalignment and grinding wheel imbalance. When compared to conventional single-wheel grinding, the results indicate twin-wheel grinding reduces rail vibration, leading to low incidence of grinding chatter and better grinding performance. However, feed force misalignment between the two grinding wheels can lead to increased chatter, and both resonance and chatter may occur at lower grinding speeds as feed force misalignment increases. Results also show that feed force misalignment has a greater effect on rail vibration and chatter than imbalance asynchronization between the two grinding wheels.

Cheng, C. C.; Kuo, C. P.; Wang, F. C.; Cheng, W. N.

2011-03-01

300

Recent developments in modeling of hot rolling processes: Part I - Fundamentals  

Science.gov (United States)

The numerical simulation of industrial rolling processes has gained substantial relevance over the past decades. A large variety of models have been put forward to simulate single and multiple rolling passes taking various interactions between the process, the microstructure evolution and the rolling mill into account. On the one hand, these include sophisticated approaches which couple models on all scales from the product's microstructure level up to the elastic behavior of the roll stand. On the other hand, simplified but fast models are used for on-line process control and automatic pass schedule optimization. This publication gives a short overview of the fundamental equations used in modeling of hot rolling of metals. Part II of this paper will present selected applications of hot rolling simulations.

Hirt, Gerhard; Bambach, Markus; Seuren, Simon; Henke, Thomas; Lohmar, Johannes

2013-05-01

 
 
 
 
301

Influence of clinker grinding-aids on the intrinsic characteristics of cements and on the behaviour of mortars  

Directory of Open Access Journals (Sweden)

Full Text Available In the production of portland cement, grinding aids are used to improve the grinding stage and reduce the energy required to achieve the required fineness. These additives remain in the final product and they might influence the characteristics and properties of the cement, and thus, mortar and concrete. This paper presents an evaluation of two grinding-aid additives used in the production of portland cement ground in a ball mill at a laboratory stage, with suitable proportions of portland cement clinker and gypsum. A control cement mix was also produced without using any admixture and the results are shown on a comparative basis. Conclusions indicate that grinding-aids additives have some influence on the characteristics of portland cement produced, increasing their specific surface and modifying microstructure and its packing ability. Mortars and concretes made with cements ground with the addition of gringing-aids exhibit higher strength at any age and a reduced water demand. Special attention should be taken to consider any interaction with water-reducing admixture in concretes and mortars.

En la fabricación de cemento portland es una práctica creciente la utilización de aditivos para optimizar el proceso de molienda; éstos quedan incorporados en el producto final y pueden influir sobre las características y propiedades del cemento, morteros y hormigones. En este trabajo se presenta la evaluación de dos aditivos comerciales en la molienda conjunta de clínker de cemento portland y yeso comercial, tratados en un molino a bolas a escala de laboratorio, en forma comparativa con un cemento sin aditivo producido en forma equivalente. Las conclusiones indican que los aditivos de molienda tienen influencia en las características del cemento resultante, incrementando su superficie y modificando su microestructura y estado de agregación; los morteros mejoran sus prestaciones mecánicas a todas las edades y se reduce la demanda de agua, aunque debe prestarse cuidado a las posibles interacciones con aditivos reductores de agua de hormigones.

Fernández Luco, L.

2003-12-01

302

The effect of processing parameters on energy consumption of ball mill refiner for chocolate  

Directory of Open Access Journals (Sweden)

Full Text Available A laboratory ball mill consisting of vertical cylinder, equipped with a rotating shaft with arms, and filled with steel balls as a grinding medium has been used in the experiments. The aim of the study was to examine the effect of agitator shaft speed and amount of grinding media (steel balls on power requirements and energy consumption of a ball mill. With constant mass of the steel balls (20 kg, 30 kg and 40 kg, the agitator shaft speed was increased from 10% to 100% of the maximum speed which corresponds to a speed of 50 rpm. The power consumption (W was recorded upon which milling energy consumption (J/kg has been calculated. The results were statistically analyzed using ANOVA. The increase of the agitator shaft speed, in steps of 10% to the maximum speed of 50 rpm, led to a statistically significant increase in milling energy consumption. At low agitator shaft speed (10%, increase in the mass of the steel balls had no influence on the power requirements. Power requirements for the grinding runs using 30 kg and 40 kg are similar and higher compared to power requirement in trial with 20 kg, as agitator shaft speed increases from 20% to 70%. At high agitator shaft speeds (?80%, increase in steel balls mass led to the significant increase in power requirements of the ball mill.

Fišteš Aleksandar Z.

2013-01-01

303

Spray Rolling Aluminum Strip  

Energy Technology Data Exchange (ETDEWEB)

Spray forming is a competitive low-cost alternative to ingot metallurgy for manufacturing ferrous and non-ferrous alloy shapes. It produces materials with a reduced number of processing steps, while maintaining materials properties, with the possibility of near-net-shape manufacturing. However, there are several hurdles to large-scale commercial adoption of spray forming: 1) ensuring strip is consistently flat, 2) eliminating porosity, particularly at the deposit/substrate interface, and 3) improving material yield. Through this program, a new strip/sheet casting process, termed spray rolling, has been developed, which is an innovative manufacturing technique to produce aluminum net-shape products. Spray rolling combines the benefits of twin-roll casting and conventional spray forming, showing a promising potential to overcome the above hurdles associated with spray forming. Spray rolling requires less energy and generates less scrap than conventional processes and, consequently, enables the development of materials with lower environmental impacts in both processing and final products. Spray Rolling was developed as a collaborative project between the University of California-Davis, the Colorado School of Mines, the Idaho National Engineering and Environmental Laboratory, and an industry team. The following objectives of this project were achieved: (1) Demonstration of the feasibility of the spray rolling process at the bench-scale level and evaluation of the materials properties of spray rolled aluminum strip alloys; and (2) Demonstration of 2X scalability of the process and documentation of technical hurdles to further scale up and initiate technology transfer to industry for eventual commercialization of the process.

Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.

2006-05-10

304

A new transducer for local load measurements of friction and roll pressure in cold flat rolling  

DEFF Research Database (Denmark)

The only way to establish the true rolling pressure and the true friction condition in cold rolling is to conduct measurements in the roll bite. A new transducer design is therefore proposed, in order to overcome problems in previous measurements in the past 70 years. The new idea is to increase the contact surface of the transducer, to be larger than the arc of contact. This is in contrast to the smaller and smaller contact pin design that has been prevailing. The measurements were conducted during cold dry rolling of both copper strips and stainless steel strips in a pilot mill. The recordings were selected from a steady state with no disturbance from the material flow. The transducer was able to simultaneously measure both the normal pressure and the friction stress. An estimation of the coefficient of friction was accordingly performed. The new transducer works very well, it was seen to be robust and able to avoid signal disturbance. The pressure and friction stress distribution results was as expected bythe authors and showed good reproducibility, together with a proven agreement between recorded and simulated signals.

Wanheim, Tarras; Henningsen, Poul

2006-01-01

305

Rolling element fatigue testing of gear materials  

Science.gov (United States)

Rolling element fatigue lives of nine alloys were evaluated in Rolling Contact (RC) rigs. Test conditions included a Hertzian stress at 4,826 MPa (700 ksi), a rolling speed of 6.23 m/sec (245 in/sec.). Tests were run with a Type I oil (MIL-L-7808G) at room temperature. B-10 lives (10% failure rate) of alloys were compared versus reference alloys, VIM-VAR AISI M-50 and VAR AISI 9310. Six case carburizing alloys (AISI 9310, CBS600, CBS1000M, EX00014, Vasco X-2 and EX00053) and three through-hardening alloys (AISI M-50, VascoMax 350 and Vasco Matrix 2 evaluated, showed RCF performance inferior or equivalent to that of AISI 9310 and AISI M-50. It was also found that the effects of vacuum melting processes, different tempering temperatures, freezing cycle during heat treating, shot peening, gold plating and chrome plating employed in the present investigation did not significantly affect RCF life.

Nahm, A. H.

1978-01-01

306

Sensitivity of stress corrosion cracking of stainless steel to surface machining and grinding procedure  

International Nuclear Information System (INIS)

Highlights: ? Pits were more likely to be associated with surface defects induced by machining but tendency was not overwhelming. ? Stress corrosion cracks developed from pits, with cracks emerging both at the surface and within the pit. ? Stress corrosion cracking was attributed to a combination of high tensile residual stress and nanocrystalline layer. ? Stress corrosion cracking was also observed where net stress was compressive; a novel peeling stress effect is proposed. - Abstract: An investigation has been undertaken to establish the effect of surface preparation method on the susceptibility of a 304 stainless steel to stress corrosion cracking under simulated atmospheric corrosion conditions. MgCl2 was deposited onto four-point bend specimens, which were then placed in a chamber with a relative humidity of 45% and temperature of 60 deg. C. These test conditions were designed to reflect external exposure of stainless steel components in industrial plant, including nuclear reactor components, situated in a coastal region, but with the severity of the exposure conditions enhanced to allow discrimination of the effect of surface preparation in a short timescale (up to 1500 h). Four surface preparation methods were evaluated: transverse grinding, longitudinal grinding, transverse dressing using an abrasive flap wheel, and transverse milling. For each case, surface topography, surface defect mapping, near-surface microhardness mapping, residual stricrohardness mapping, residual stress and electron back-scattered diffraction measurements were undertaken. Stress corrosion cracks were observed for the ground and milled specimens but not for the dressed specimens, with cracks apparently originating at corrosion pits. The density of cracks increased in the order: transverse ground, milled and longitudinal ground, with the cracks notably much smaller in length for the transverse ground condition. The propensity for cracking could be linked to the high residual stress and apparent nanocrystalline microstructure at the surface. There was a greater propensity for pitting to initiate at local defect sites on the surface (laps, deeper grooves). However, the tendency was not overwhelming, suggesting that other factors such as more general roughness or the distribution of MnS inclusions had an influence, perhaps reflecting the severity of the environment.

307

Ultraprecision grinding of optical materials for high-power lasers  

Science.gov (United States)

Grinding is considered to be a rough machining process in the field of optics; a polishing process must follow the grinding process for getting optical-quality surfaces. An ultraprecision surface grinder with hydrostatic oil bearings and a glass-ceramic spindle of extremely low thermal expansion was developed to get smooth optical surfaces without any polishing process. Various optical materials such as NbF1, BK7, LHG08 fused silica, KTP, KDP and CLBO were ground into optical surfaces after empirically determining the conditions required to attain ductile-mode grinding. An extremely smooth surface less than 0.1 nm rms was obtained on BK7 glass by the ultraprecision grinding process. The laser-induced damage threshold was measured on variously finished LHG-8 laser glass at (lambda) equals 1.053 micrometers and 1-ns pulse width. The damage threshold was measured at 22.2 J/cm2 on a ground surface with the polarization parallel to the grinding direction. This number is higher than that obtained by optical polish. The damage threshold of 293 J/cm2 was also obtained on a ground LHG-8 glass surface at (lambda) equals 1.053 micrometers and 30-ns pulse width.

Namba, Yoshiharu; Yoshida, Kunio; Yoshida, Hidetsugu; Nakai, Sadao

1998-04-01

308

Development of morphology in laser dressed grinding wheels  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The paper describes the development of faceted morphology in laser dressed grinding wheels.Design/methodology/approach: The approach used in the paper is based on locally melting a vitrified grinding wheel and measuring features such as grain size, cooling rate and melt depth as a function of laser fluence and relating these measures to the morphology shown in the microstructures presented in the paper.Findings: The findings of this course of research lead the authors to believe that a specific morphology is dependent upon cooling rate and laser fluence.Research limitations/implications: The findings show that further research is required to fully understand how certain morphologies form as a function of cooling rate and laser fluence. It should be noted that morphologies observed in laser processed grinding wheels include cellular and fully dendritic morphologies in addition to faceted vertices.Practical implications: The results imply that laser dressed grinding wheels can be used for machining different materials at different grinding speeds. The paper also shows that much development is needed to identify laser processing conditions that are appropriate for different workpiece materials.Originality/value: The paper shows that different morphologies can be used to machine workpiece materials under different conditions. The originality in the paper is focused on the formation on minute cutting points using increasing laser fluences.

M.J. Jackson

2007-05-01

309

Ship Roll Damping Control  

DEFF Research Database (Denmark)

The technical feasibility of roll motion control devices has been amply demonstrated for over 100 years. Performance, however, can still fall short of expectations because of difficulties associated with control system designs, which have proven to be far from trivial due to fundamental performance limitations and large variations of the spectral characteristics of wave-induced roll motion. This tutorial paper presents an account of the development of various ship roll motion control systems together with the challenges associated with their design. It discusses the assessment of performance and the applicability of different mathematical models, and it surveys the control methods that have been implemented and validated with full scale experiments. The paper also presents an outlook on what are believed to be potential areas of research within this topic.

Blanke, Mogens

2012-01-01

310

Fast-roll inflation  

CERN Document Server

A novel class of exact solutions of inflationary dynamics with a specific form of a scalar potential is given based on a "fast-roll" ansatz, where the even-order slow-roll parameters approach to a nonnegligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime. Due to the rapid evolution of the background dynamics, the would-be decaying mode of the linear curvature perturbation may behave as a growing mode depending on the value of the model parameter, while the other mode remains constant. For the parameters giving a slightly red-tilted primordial power spectrum, the unwanted anomalous growth of the curvature perturbation is inevitable, which is similar to the case of the so-called ultra-slow-roll inflation.

Motohashi, Hayato; Yokoyama, Jun'ichi

2014-01-01

311

Mechanochemical effects in planetary ball milling of quartz particles  

Energy Technology Data Exchange (ETDEWEB)

The mechanochemical phenomena that occurred in the fine grinding process of quartz particles using a planetary ball mill were investigated. The fundamental physical properties of ground products were estimated by measuring the particle size distribution, specific surface area, and particle density. The physico-chemical change of particle's such as amorphorization and phase conversion were also analyzed by XRD, IR spectrometry and DTA. It was confirmed that fine ground quartz was a mechanochemical product. >From the measurements, the density was about 2.24 g/cm{sup 3}, which was similar to that of vitreous silica(2.20 g/cm{sup 3}). This fact suggests that the sample was amorphorized during grinding. The amorphorization structure of the sample accords with the analysis of the X-ray test, and a result of the DTA, its endothermic peak intensity was decreased during a conversion step at 573 deg.C. Therefore, it was shown that the volumetric amount of the crystalline quartz rapidly decreased in relation to the amorphorized formation. The result of IR spectrometry shows that the Si-O bonding of quartz is broken by mechanical energy and silanol group were formed. The grinding process using the planetary ball mill was classified into three stages: size reduction, aggregation, and mechanochemically agglomeration. (author). 11 refs., 1 tab., 8 figs.

Shin, Hee-Young [Korea Institute of Geology Mining and Materials, Taejeon(Korea); Park, Jai-Koo [Hanyang University, Seoul(Korea)

2000-10-31

312

Effects of wet ball milling on lead stabilization and particle size variation in municipal solid waste incinerator fly ash  

International Nuclear Information System (INIS)

Water-extracted municipal solid waste incinerator (MSWI) fly ash was treated by a process of wet ball milling, using desalinated water as the milling solution. We investigated the influence of the milling process on the partitioning and leaching characteristics of lead (Pb) and the particle size distribution. The results show that 93.11% of the Pb was partitioned into the milled ash, 2.60% to the milling balls, and 0.17% to the inner surface of the milling jar, while amounts lower than the detection limit remained in the milled solution. As tested by the toxicity characteristic leaching procedure (TCLP), the leaching of Pb was inhibited after short-term grinding (from 5.2 to 1.2 mg/L after 1 h of milling), and further reduced by about 96% after 96 h of ball milling. The mobility of the heavy metal was analyzed after a sequential extraction procedure. The results also show that Pb tended to become more stable after milling. The size distribution of particles was analyzed by a laser particle diameter analyzer and their morphology during grinding was observed using scanning electron microscopy. The median size of the fly ash decreased significantly from 36 to 5 ?m after 0.5 h of milling, but then only slightly, from 5 to 2 ?m, with further milling from 0.5 to 96 h, due to the concurrent actions of fragmentation and/or agglomeration. The reason for the stabilization of Pb by ball milling was probably that Pb was sealed in the milled fly ash during the fragmentation and agglomeration of particles.

313

Plastic-deformation zone length and the allowable speed for ingotless rolling  

Science.gov (United States)

To realize a casting-rolling process in two-high units (mills), it is reasonable to maintain a process speed at which the level of the liquid phase does not fall below the level of the plane passing through the roll axes. Dependences are obtained to estimate possible oscillations in the plastic-deformation zone length with allowance for possible deviations of the ingot-rim thickness and to determine the allowable exit strip velocity that provides the required strain.

Brovman, M. Ya.; Nikolaev, V. A.; Polukhin, V. P.

2007-02-01

314

Multi-scale modelling of hot rolled dual-phase steels for process design  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis investigates and models the austenite to ferrite transformation in the hot rolling of two different dual phase steels. The investigation has been carried out in a deformation dilatometer as well as a 4-stand pilot rolling mill. Three different modelling approaches were employed to give different aspects of information and for different applications. Macroscopic kinetics model base on JMAK rate form gives simple overall kinetics information and indicates the appropriate process win...

Suwanpinij, Piyada

2012-01-01

315

Offensive Rolling in Sambo  

Directory of Open Access Journals (Sweden)

Full Text Available In recent years the Soviet born martial art of sambo has become increasingly well known in martial art circles. This is largely due to the success of sambo fighters in various mixed martial art venues. Offered here is a brief description of sambo’s development as well as a delineation of one of sambo’s hallmark strategies: offensive rolling. Examples of proper forward rolling and three related offensive techniques are presented. This paper provides a brief introduction to sambo’s history and one of its key tactical philosophies.

Stephen Koepfer

2012-07-01

316

Ship Roll Motion Control  

DEFF Research Database (Denmark)

The technical feasibility of roll motion control devices has been amply demonstrated for over 100 years. Performance, however, can still fall short of expectations because of deciencies in control system designs, which have proven to be far from trivial due to fundamental performance limitations. This tutorial paper presents an account of the development of various ship roll motion control systems and the challenges associated with their design. The paper discusses how to assess performance, the applicability of dierent models, and control methods that have been applied in the past.

Blanke, Mogens Technical University of Denmark,

2010-01-01

317

Determination of the relative position between grinding wheel and a cylindrical workpiece on a 7 axis grinding machine by acoustic emission  

Directory of Open Access Journals (Sweden)

Full Text Available The contact between grinding wheel and workpiece in the grinding process is recognized by acoustic emission (AE. Two acoustic emission monitoring systems (MS were integrated into a 3 axis CNC grinding machine. A laptop allows the signal acquisition and visualization. The acquired AE RMS signals from the contact between tool and workpiece are analyzed permitting to establish the most suitable AE monitoring system to recognize the contact in a particular grinding machine. In a second experimental setup the selected MS was installed on a 7 axis tool grinding machine at an industrial partner. At this partner, the relative position between grinding wheel and workpiece was previously determined manually. This procedure has a direct influence on the results depending on the technical skills of the operator. The automation of this activity supported by acoustic emission has led to satisfactory results regarding the relative position between grinding wheel and workpiece and contributed to the setup time reduction.

Walter Lindolfo Weingaertner

2012-03-01

318

Methodology for automatic selection of passes in surface grinding  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The main purpose of this work is the development of computational tools in order to assist the on-line automatic detection of burn in the surface grinding process. Most of the parameters currently employed in the burning recognition (DPO, FKS, DPKS, DIFP, among others) do not incorporate routines fo [...] r automatic selection of the grinding passes, therefore, requiring the user’s interference for the choice of the active region. Several methods were employed in the passes extraction; however, those with the best results are presented in this article. Tests carried out in a surface-grinding machine have shown the success of the algorithms developed for pass extraction.

Fábio R. L., Dotto; Paulo Roberto de, Aguiar; Rogério, Thomazella; Eduardo Carlos, Bianchi.

2007-03-01

319

Can seeds help mice with the daily grind?  

Science.gov (United States)

Some laboratory mice gnaw food pellets without ingesting much of the gnawed material, resulting in the production of waste material called 'orts'. The fact that this food grinding behavior is not seen in all individuals of a particular strain suggests that it might be abnormal, and thus indicate a welfare concern. Furthermore, the increased rate of feed consumption and cage soiling is undesirable from a husbandry perspective. To try to determine possible motivations for the behavior, and identify potential treatments, outbred Crl:CD1(Icr) mice exhibiting food grinding were selected for one of three treatments placed in the feeder: no enrichment, a chewing device, or sunflower seeds. Both enrichment groups showed a significant decrease (P grinding, and that a nutritional motivation may also be involved. PMID:23760566

Pritchett-Corning, K R; Keefe, R; Garner, J P; Gaskill, B N

2013-10-01

320

In-process grinding monitoring through acoustic emission  

Directory of Open Access Journals (Sweden)

Full Text Available This work aims to investigate the efficiency of digital signal processing tools of acoustic emission signals in order to detect thermal damages in grinding processes. To accomplish such a goal, an experimental work was carried out for 15 runs in a surface grinding machine operating with an aluminum oxide grinding wheel and ABNT 1045 Steel as work material. The acoustic emission signals were acquired from a fixed sensor placed on the workpiece holder. A high sampling rate data acquisition system working at 2.5 MHz was used to collect the raw acoustic emission instead of the root mean square value usually employed. Many statistical analyses have shown to be effective to detect burn, such as the root mean square (RMS, correlation of the AE, constant false alarm rate (CFAR, ratio of power (ROP and mean-value deviance (MVD. However, the CFAR, ROP, Kurtosis and correlation of the AE have been presented more sensitive than the RMS.

Paulo R. Aguiar

2006-03-01

 
 
 
 
321

Quantitative control and optimization of grinding and polishing processes  

International Nuclear Information System (INIS)

The possibilities for the control and optimization of preparation processes and for the quantitative description of the quality of polished specimens are discussed using sintered aluminium oxide bodies as an example. A microscopic photometer and a TV image analyser were used in addition to the reflected light and scanning electron microscopes to control the grinding, lapping, and polishing processes. The photometer gave a very sensitive record of the nature of the surface from the grinding and lapping processes as well as from the first polishing step, whereas the fraction of regions that had not been levelled (pores and popouts) during polishing could be determined with an image analyser. Photographic documentation of the various stages of grinding, lapping, and polishing proved to be useful in selecting the most suitable method of preparation from the series of photographs. (orig.)

322

REVIEW OF DRESSING AND TRUING OPERATIONS FOR GRINDING WHEELS  

Directory of Open Access Journals (Sweden)

Full Text Available Grinding is an operation applied in almost every type of manufacturing process. It aims to produce high surface finish and to maintain close tolerances in the manufactured product. To make the grinding operation more productive and efficient, dressing and truing operations are performed on the grinding wheels. Various techniques are available and are used for the same. Since many permutations and combinations exists among the factors like economics, efficiency, accuracy, complexity, etc. of the dressing process, so continuous efforts are made to develop or adopt a technique that gives the best result while fulfilling the maximum number of factors. This can be accomplished by comparing the present techniques on the same ground. With this aim, the unconventional techniques with in-process configuration were developed that have several advantages over theirconventional counterparts.

UJJAWAL MAYANK SRIVASTAVA

2013-01-01

323

Flow Stress Evaluation in Hot Rolling of Steel  

Science.gov (United States)

In this paper, an inverse analysis technique is used to obtain the flow curve of materials in a hot rolling finishing mill. This technique is based on minimization of the differences between the experimental and computed values. The flow curves and the friction coefficients at roll/work-piece interface are derived from two different models. Model I is based on simple slab method of analysis. Model II is based on a modified slab method in which the effect of shear stress in calculating the rolling force and torque is taken into account. It is shown that the developed inverse analysis technique is reliable and can simultaneously determine a more accurate flow stress for the material as well as a better estimation for the interface friction factors.

Aghasafari, P.; Salimi, M.; Daraei, A.

2014-08-01

324

Slitting criterion for various rolling speeds in MSR rolling process  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The main idea of MSR technology is the capability of producing two, three, four and even five rods simultaneously from a single strip in a hot rolling process. Correctly separation of the joined strips is the one of the mainly problem in MSR process. Changing the rolling speed may causes easier of the strand division. In this paper results of the computer simulation of the double slitting rolling process were presented.Design/methodology/approach: For numerical modelling of the multi rolling process a computer program Forge 2005, based by the finished element method was used. As a slitting criterion normalised Cockroft – Latham criterion was used.Findings: For the analysis performed in this study, it was found that increasing of the rolling speed causes of increasing the normalized Cockroft – Latham criterion. For the small values of rolling velocity the strip separation was easier.Research limitations/implications: Multi Slit Rolling process is applied in ribbed rods rolling. Adjusting of the rolling speed in multi slit rolling process could improve of the slitting band to the separated strips.Originality/value: Incorrect construction or bad gap matching could cause lack of separation propelled slitting rolls. The separation of the band is effected by means of separating rollers, which shape must be properly designed to suit to the slitting pass. Changing of the rolling speed could improve of the separation to the single strips.

A. Stefanik

2008-03-01

325

21 CFR 173.320 - Chemicals for controlling microorganisms in cane-sugar and beet-sugar mills.  

Science.gov (United States)

...They are applied to the sugar mill grinding, crusher, and/or diffuser...2-dibromo-3-nitrilopropionamide are not authorized for use in animal feed Not more than 10.0 and not less...salts are not authorized for use in animal feed. (6) Single additive for...

2010-04-01

326

21 CFR 173.320 - Chemicals for controlling microorganisms in cane-sugar and beet-sugar mills.  

Science.gov (United States)

...b) They are applied to the sugar mill grinding, crusher, and/or diffuser systems...2-dibromo-3-nitrilopropionamide are not authorized for use in animal feed Not more than 10.0 and not less than...salts are not authorized for use in animal feed. (6) Single additive for...

2010-04-01

327

Possibilities of Pelletizing and Briquetting of Dusts from Castings Grinding  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Foundry dust can be divided into three groups: metallic dust with Fe content over 70%, mixed dust with Fe or SiO2 content between 10 –70% and sand wastes with minimum content of SiO2 about 70%. Dust from castings grinding with high Fe content (87.9%) is still landfillin Slovakia. The aim of experiments with dust from grinding has been to find the cheapest way of dust agglomeration with minimumamount of binder because of melting in the electric induction furnace. The dust was pelletized and ...

Pribulova?, A.; Baricova?, D.; Futas?, P.; Gengel?, P.

2010-01-01

328

Performance analysis of magnesium phosphate cement mortar containing grinding dust  

Directory of Open Access Journals (Sweden)

Full Text Available Magnesium phosphate cement materials are formed by reacting magnesium oxide with water-soluble phosphates such as monoammonium dihydrogen phosphate (ADP, which solidifies at ambient temperature through the formation of hydrated phases in the material. Cylindrical specimens of magnesium phosphate cement were molded and varying amounts (0 to 30% weight of grinding dust were added to the ceramic matrices. The influence of the addition of grinding dust on the characteristics of the mortars in terms of microstructure (SEM, mechanical strength and capillary water absorption was verified. The results obtained proved very satisfactory for the use of this waste as an additive in magnesium phosphate mortars.

Daniel Véras Ribeiro

2009-03-01

329

Analysis of cement superplasticizers and grinding aids a literature survey  

Energy Technology Data Exchange (ETDEWEB)

This literature survey reviews the methods for analysis of cement plasticizers and organic grounding aids in cement solutions in preparation of grouts/concrete and methods for determination of plasticizers and grinding aids in groundwater conditions. The survey focuses on three different types of superplasticizers: sulphonated naphthalene condensates, sulphonated melamine condensates and polycarboxylates. There are various organic grinding aids, such as alkanolamines, glycols or phenolic compounds, used in the cement industry. This review is concerned with the following compounds: triethylenetetramine, tetraethylenepentamine, diethanolamine, triethanolamine, triisopropanolamine, ethyleneglycol, diethyleneglycol, aminoethylethanolamine, hydroxyethyl diethylenetriamine and phenol. (orig.)

Ervanne, H.; Hakanen, M. [Helsinki Univ. (Finland). Lab. of Radiochemistry

2007-04-15

330

Prototypical Implementation of a Remanufacturing Oriented Grinding Machine  

DEFF Research Database (Denmark)

Considering the current scenario of limited resources and increased environmental regulations, frameworks to support the development of more sustainable production equipment are sought. Remanufacturing can bring benefits in terms of extending product lifetime by allowing multiple usage phases. Due to the diversity of mechanical, electrical and electronic components with different degree of replacement criteria of grinding machines, remanufacturing emerges as a relevant approach. The aim is to present a prototypical implementation of a remanufacturing oriented grinding machine, based on a storyboard which describes the main activities carried out during the machine lifecycle, including a comparative LCA of end of life scenarios.

da Silva, Eraldo Jannone; Ometto, Aldo Roberto

2013-01-01

331

High-speed, low-damage grinding of advanced ceramics Phase 1. Final report  

Energy Technology Data Exchange (ETDEWEB)

In manufacture of structural ceramic components, grinding costs can comprise up to 80% of the entire manufacturing cost. Most of these costs arise from the conventional multi-step grinding process with numerous grinding wheels and additional capital equipment, perishable dressing tools, and labor. In an attempt to reduce structural ceramic grinding costs, a feasibility investigation was undertaken to develop a single step, roughing-finishing process suitable for producing high-quality silicon nitride ceramic parts at high material removal rates at lower cost than traditional, multi-stage grinding. This feasibility study employed combined use of laboratory grinding tests, mathematical grinding models, and characterization of resultant material surface condition. More specifically, this Phase 1 final report provides a technical overview of High-Speed, Low-Damage (HSLD) ceramic grinding and the conditions necessary to achieve the small grain depths of cut necessary for low damage grinding while operating at relatively high material removal rates. Particular issues addressed include determining effects of wheel speed and material removal rate on resulting mode of material removal (ductile or brittle fracture), limiting grinding forces, calculation of approximate grinding zone temperatures developed during HSLD grinding, and developing the experimental systems necessary for determining HSLD grinding energy partition relationships. In addition, practical considerations for production utilization of the HSLD process are also discussed.

Kovach, J.A. [Eaton Corp., Willoughby Hills, OH (United States). Mfg. Technologies Center; Malkin, S. [Univ. of Massachusetts (United States)

1995-03-01

332

Effect of milling variables on powder character and sintering behaviour of 434L ferritic stainless steel-Al2O3 composites  

International Nuclear Information System (INIS)

Ball milling of ferritic stainless steel-4 vol% Al2O3 powder was carried out for the duration up to 222 ks. Attritor milling of ferritic stainless steel-6 vol% Al2O3 were also carried out for the duration up to 32.4 ks. The characterization of the milled powders were performed. The sintering of ball milled powders was carried out at 1623 K for 10.8 ks in hydrogen. The premix of as received stainless steel powder and the attritor milled powder was also sintered at 1623 K for 3.6 ks in hydrogen. The results showed that an optimum ball milling period in between 58 and 173 ks was required to achieve better sintered properties. The attritor milling was more effective in grinding the powders as compared to ball milling, and the sinterability was also higher for such powders. (author)

333

Analytical inverse solution for coupled thermoelastic problem for the evaluation of contact stress during steel strip rolling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Knowledge of the contact stress between roll and strip is a critical factor in modern, high-speed rolling mills. Previously two inverse analytical methods have been developed to determine the elastic contact stress on the one hand and the heat flux or the temperature in the whole roll (and especially at the surface) on the other hand, by measuring the stress tensor inside the roll body with fibre optics and by measuring the temperature with a thermocouple fully embedded at only one point insi...

Weisz-patrault, Daniel; Ehrlacher, Alain; Legrand, Nicolas

2013-01-01

334

Development of Roller Ends Forced-Contact Model and Cambering Technology for UCM Temper Mill (I——Development of Roller Ends Forced-Contact Model and the Computational Model of Flatness for UCM temper mill  

Directory of Open Access Journals (Sweden)

Full Text Available Roller ends forced-contact and overmuch roll consumption are the widespread problems in temper rolling process of thin strip for two-stand UCM temper mill. Fully thinking the equipment and technology characteristics of UCM temper mill, we took the newly-built 1220 UCM temper mill of Baosteel as the research object in this paper. A model of roller ends forced-contact and a calculation model of flatness for UCM temper mill are established after a great deal of site tracing and theoretical researches. On this basis, an optimal mathematical model of roll shape which is suited for UCM temper mill is developed. Working roll curve is the combination of cosine curve and high order curve. The cosine subentry is used to control edge wave, the high order curve subentry is used to control roller ends forced-contact. Furthermore, the chamfering curve of middle roller end is optimized. Those are the innovations. Through the above-mentioned technology, pressure distribution between rollers caused by the shift of middle roll becomes more homogeneous, pressure peak disappeared, working life of roll is improved effectively as well. Relevant technologies have been used to the practice of 1220 UCM temper mill of Baosteel and have achieved good use effects, which is of further extending application value [1].

Zhenhua Bai

2011-07-01

335

Paragraph 24 Crushing, Grinding or other Size Reduction of Waste Bricks, Tiles or Concrete  

...Crushing, Grinding or other Size Reduction of Waste Bricks, Tiles or...crushing, grinding, or other size reduction of waste bricks, tiles and...be stored prior to size reduction at any one time....

336

Graphic presentation of information of acoustic monitoring of stream grinding process  

Directory of Open Access Journals (Sweden)

Full Text Available The theoretical and experimental mechanisms of thin grinding the loose materials are analyzed. The relation of the density function of acoustic signal amplitudes of grinding process to the degree of loading the jets by material is established.

N.S. Pryadko

2012-04-01

337

Structure and properties of rolled strips of microalloyed steel type 10KhSND  

International Nuclear Information System (INIS)

The paper presents an investigation of the structure and properties of 16 and 22 mm thick sheets of microalloyed steel of 10KhSND type (10Kh5SND type with a decreased content of nickel) which were rolled on a plate mill and were subjected to normalization or martempering. It is shown that the rolled stock of S390K steel, which was microalloyed with titanium, aluminium and nitrogen, after normalization features high mechanical properties and cold resistance in line with the requirements of state standard GOST 27772. Vanadium microalloying of S390K steel improves the weldability of the rolled products. 4 figs., 3 tabs

338

Investigation into the causes of cracking of 2024 aluminium alloy during rolling operation  

International Nuclear Information System (INIS)

Aluminium alloy 2024 bars cracked during cold rolling to produce strips conforming to T-3 temper designation. The specimens had reduced to 10 mm X 10 mm size by hot rolling rectangular ingots of size 25 mm X 25 mm in 3 passes using the rolling mill. Microscopic studies of the cracked specimens revealed the presence of inclusions on the grain boundaries and in the fracture valleys. Energy dispersive X-ray analysis (EDAX) indicated that inclusions were rich in iron. Fractrogapy of fracture specimens were carried out using both optical scanning electron microscopy which indicated brittle fracture due to the presence of iron inclusions. (author)

339

Micro-Plasto-Hydrodynamic Lubrication a Fundamental Mechanism in Cold Rolling  

DEFF Research Database (Denmark)

This paper presents recent investigations in Micro-Plasto-Hydrodynamic (MPH) lubrication. Industrial evidences of the existence of MPH lubrication mechanism for cold rolling processes are presented. A new lubrication model developed for strip drawing processes is then applied to predict the MPH lubrication initiation and MPH lubrication extension along the tool-piece solid contacts initially in boundary lubrication regime. Finally, it is shown how this new MPH lubrication model can be implemented in a cold rolling model to maximize mills capabilities, determine optimum rolling oils properties and predict roughness transfer.

Bech, Jakob Ilsted

2014-01-01

340

Formation of the structure and properties of the titanium alloys of the transient class after warm rolling  

International Nuclear Information System (INIS)

The effect of warm rolling on strengthening the VT22 and VT22I titanium alloys is studied. Warm rolling was carried out within the temperature range of 650-700 deg C with hold time both before and after the beginning of the ??? transformations. It is established, that warm rolling together with the ?-phase decay makes it possible to increase sufficiently the plasticity along with obtaining high strength. It is connected with diffusion, grinding and more uniform distribution of particles after the second phase by deformation. It is noted, that conduct of rolling after isothermal hold time during one or several runs differently effects the regularities of the process of structural and phase transformations in titanium alloys

 
 
 
 
341

Modeling, simulation and identification for control of tandem cold metal rolling  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes a modeling procedure for tandem cold metal rolling, including the linearization step and system identification for control. The tandem cold rolling process is described by a mathematical model based on algebraic equations developed for control purposes and empirical relations. A state-space model is derived and detailed analyses in open loop are presented, concerning the sensitivity with regard to the variations in process parameters and results for the application of a new subspace identification method are compared with classical methodologies. Therefore, this work intents to be a contribution for developments in new control strategies for tandem cold rolling process that offer the potential to reduce the design efforts, the commissioning time and maintenance in rolling mills. The preliminary results obtained with this model have shown reasonable agreement with operational data presented at literature for industrial cold rolling process.

Péricles Guedes Alves

2012-12-01

342

Microstructure and properties of hot roll bonding layer of dissimilar metals. 2. Bonding interface microstructure of Zr/stainless steel by hot roll bonding and its controlling  

International Nuclear Information System (INIS)

The hot roll bonding of zirconium and stainless steel inserted with tantalium was investigated using the newly developed rolling mill. The effect of hot rolling temperatures of zirconium/stainless steel joints on bonding interface structure was evaluated. Intermetallic compound layer containing cracks was observed at the bonding interface between stainless steel and tantalium when the rolling temperature was above 1373K. The hardness of the bonding layer of zirconium and tantalium bonded above 1273K was higher than tantalium or zirconium base metal in spite of absence of intermetallic compound. The growth of reaction layer at the stainless steel and tantalium interface and at the tantalium and zirconium interface was conforming a parabolic low when that was isothermally heated after hot roll bonding, and the growth rate was almost same as that of static diffusion bonding without using hot roll bonding process. It is estimated that the strain caused by hot roll bonding gives no effect on the growth of reaction layer. It was confirmed that the dissimilar joint of zirconium and stainless steel with insert of tantalium having the sound bonding interface were obtained at the suitable bonding temperature of 1173K by the usage of the newly developed hot roll bonding process. (author)

343

Research of the residual stress in grinding surface of glass-ceramics  

Science.gov (United States)

We simulated the process of grinding glass-ceramics with the finite element simulation method. During the simulation, we considered the impact of changes in various process parameters on the grinding and analysis the simulation results of the residual stress at last. The target of this research is to provide some basic reference for the choice of the glass-ceramics grinding process parameters.

Zhou, Peng; Guo, Peiji

2014-08-01

344

Creep feed (single path) and conventional (multi-path) grinding - surface structure and comparison  

Science.gov (United States)

The third to fifth order shape variations (roughness) were compared for creep feed and conventional grinding. Case hardening and high speed steel tests are quoted. The continuous, uninterrupted grooves with smooth sides produced by creep feed grinding contrast with the interrupted grooves characterized by ridges and marked plastic deformation in the case of conventional surface grinding.

Schleich, H.

1982-07-01

345

Microstructure Evolution During Spray Rolling and Heat Treatment of 2124 Al  

Energy Technology Data Exchange (ETDEWEB)

Spray rolling is a strip casting technology that combines elements of spray forming and twin-roll casting. It consists of atomizing molten metal with a high velocity inert gas, quenching the resultant droplets in flight, and directing the spray between mill rolls. In-flight convection heat transfer from atomized droplets and conduction heat transfer at the rolls rapidly move an alloy’s latent heat. Hot deformation of the semi-solid material in the rolls results in fully consolidated, rapidly-solidified product. While similar in many ways to twin-roll casting, spray rolling is able to process a broader range of alloys and operates at a higher production rate. A laboratory-scale strip caster has been constructed at INL and used to evaluate the interplay of processing parameters and strip quality while producing strips up to 200 mm wide and 1.6 – 6.4 mm thick. Plans are underway to scale to 600 mm width and demonstrate steady-state operation. As-spray-rolled strip is characterized by a flat, uniformly thick profile with minimal porosity or segregation. This paper examines how processing parameters influence the microstructure transformations that take place during spray rolling and post-deposition heat treatment of 2124 Al.

K.M. McHugh; Y. Lin; Y. Zhou; S.B. Johnson; J.P. Delplanque; E.J. Lavernia

2006-09-01

346

Hot rolling of intermetallics FeAl phase based alloys  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The one of major problem restricting universal employment of intermetallic phase base alloy istheir low plasticity which leads to hampering their development as construction materials. The following workconcentrates on possibilities to form through rolling process the alloys with various aluminium content.Design/methodology/approach: After casting and annealing, alloy specimens were subjected to axialsymmetriccompression at temperatures ranging from 900 to 1200°C at 10 s-1 strain rates. In order to analyse theprocesses which take place during deformation, the specimens after deformation were intensely cooled with water.Structural examination was carried out using light microscopy. The process was conducted on the K -350 quartorolling mill used for hot rolling of flat products. The process was conducted in some stages in at temperaturesranging from 1200-900°C:Findings: The research carried out enabled the understanding of the phenomena taking place during hot rolling ofthe investigated alloy. An alloy with 38%at. aluminium concentration can be plastically formed at a temperature of upto 900°C, which has been also confirmed in plastometric studies conducted in the form of hot compression tests.Research limitations/implications:Practical implications: The obtained sheets can be used as constructional elements working in complex stressfields, at a high temperature and corrosive environmentsOriginality/value: The tests have shown that it is possible to form the investigated alloys through rolling processingonly where shields are applied. Rolling of the alloys without shields led to the occurrence of a grid of cracks.

G. Niewielski

2008-02-01

347

Walk and roll robot  

Science.gov (United States)

A mobile robotic unit features a main body, a plurality of legs for supporting the main body on and moving the main body in forward and reverse directions about a base surface, and a drive assembly. According to an exemplary embodiment each leg includes a respective pivotal hip joint, a pivotal knee joint, and a wheeled foot adapted to roll along the base surface. Also according to an exemplary embodiments the drive assembly includes a motor operatively associated with the hip and knee joints and the wheeled foot for independently driving pivotal movement of the hip joint and the knee joint and rolling motion of the wheeled foot. The hip joint may include a ball-and-socket-type joint interconnecting top portion of the leg to the main body, such that the hip joint is adapted to pivot said leg in a direction transverse to a forward-and-reverse direction.

Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

2011-01-01

348

Modernitetens Rolle Under Holocaust  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Projektet søger, ved hjælp af Zygmunt Baumans modernitetsteori, at afklare hvilken rolle moderniteten spillede i tilblivelsen af Holocaust. Propagandaen var en markant del af det nazistiske bureaukratiske styre, men da Bauman ikke udførligt diskuterer dette, er det et emne, vi ønsker at belyse nærmere. Dette gøres ved at analysere de to nazistiske propagandafilm, Der Ewige Jude og Jud Süss. Moderniteten indeholder faktorer, som kan være behjælpelige til en forståelse af,...

Jespersen, Simon M.

2012-01-01

349

Internal defects in rolls  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The report describes an investigation concerning two types of internal defects, axis-centered defects and near-surface defects, in rolls. Thesis for bachelor’s degree in mechanical engineering (22.5p), at the institution for engineering, physics and mathematics, Karlstad University. Ordered by Scana Steel Björneborg AB. Scana Steel Björneborg AB is one of Europe’s leading producers of heavy free-form forgings and has its own steel plant, forge, heating treatment facility and machine par...

Skoglund, Thomas

2008-01-01

350

Rolling shutter distortion correction  

Science.gov (United States)

As opposed to the global shutter, which starts and stops the light integration of each pixel at the same time by incorporating a sample-and-hold switch with analog storage in each pixel, the electronic rolling shutter found in most low-end CMOS image sensors today collects the image data row by row, analogous to an open slit that scans over the image sequentially. Each row integrates the light when the slit passes over it. Therefore, the scanlines of the image are not exposed at the same time. This sensor architecture creates an objectionable geometric distortion, known as the rolling shutter effect, for moving objects. In this paper, we address this problem by using digital image processing techniques. A mathematical model of the rolling shutter is developed. The relative image motion between the moving objects and the camera is determined by block-based motion estimation. A Bezier curve fitting is applied to smooth the resulting motion data , which are then used for the alignment of scanlines. The basic ideas behind the algorithm presented here can be generalized to deal with other complicated cases.

Liang, Chia-Kai; Peng, Yu-Chun; Chen, Homer

2005-07-01

351

Studying possibilities to improve the functional properties of metallurgical rolls  

Directory of Open Access Journals (Sweden)

Full Text Available Thc paper prcscnts rcsults nT invcst igations and at~thors' opinion on improving functional propcrtics of mciall urgicnl rolls cast fromGZOOCrMoNi 4-9-3 cast wccl. onc nf most oftcn ilscd lor rolls in scction mills. Thcsc mills Icn~urcq uickcr than flat rolls wear or 1001'spass. whar rcquircs morc Crcqocnt rcpcncr;lt ion. 'Thc machining rcquircs n rclat ivcly low hardness, which is cnsurcd hy ~ h pcc arliiic matrixof casr steel strldid. 7 % ~au thors silggcst 10 achicvc thc optimisntion o f tribologicnl propcnics through adji~stmcno~r ~ h cch cinicalcompsizion odand modificat ioll of rhc hcat trcatmcnt. In thc study prcscntcd only t hc carbon comcnt was sliyhtly incrcascd (havingciirhiclc-forming clcmcnts in Y icw rcst~ltingi n thc incrcnse in lcdcburitic carbides. Il owcvcr, !his most nhvious way or improving thcahrasivc wcar rcsisrnncc incrcascs rhc ~brcaot f rolls cracking and ~hcrcforcrc quircs verification using ttlc iracii~rc~ ncchanicsm cthod.Szaziaical analysis of random1 y sclcctcd fcw dozens of rolls havc shown Tor this gradc or cast stccl a trcnd to rcducc thc carbon contcnzby ~ h ~cn :~nurihcturcmr. ilintilining ir at thc lowcr rangc of limirs spccificd by thc standard and not to incrcasc i t . Thc analysis or thc wcnrmcchmism or suriaccs or worn out mlls madc of G2OOCrMoNi 4-3-3 cast stecl allows making suggestions on thc possihilit ics of hcatrrcarmcnt changes, what aEso has hccn prcscnrcd in ~ h pc a p .

Z. Stradomski

2008-03-01

352

Development and investigation of industrial technique for hot rolling of small cross section rods of unyielding heat resisting alloys  

International Nuclear Information System (INIS)

A hot-rolling technology has been developed for rolling rods about 14 to 16 mm in diameter made of EI826, EI929VD, EI867VD heat-resistant nickel alloys, the rods being used for manufacturing the fastening parts and for die-forging blades. The blanks preheated up to a temperature of 1160 to 1190 deg C are rolled on ''300/450'' rolling mill in two processes according to two roll pass designs; namely, oval-round for rolling the rods 16 mm in diameter, and square-oval-round for the rods 14 mm in diameter. It is the installation of the technology of manufacturing rods of decreased diameters from the above heat-resistant alloys that yields a considerable economical effect, owing to the saving of up to 40% of an expensive metal and to the reducing of the amount of work as required for manufacturing the machine parts

353

Performing in-feed type centerless grinding process on a surface grinder  

Science.gov (United States)

In our previous study, a new centerless grinding method using surface grinder was proposed. In this method, centerless grinding operations are performed by installing a compact centerless grinding unit, consisting mainly of an ultrasonic elliptic-vibration shoe, a blade and their respective holders, on the worktable of a surface grinder. During grinding, the cylindrical workpiece is held on the ultrasonic shoe and the blade, and its rotational motion is controlled by the elliptic motion of the shoe end-face. An actual unit had been produced and its performance in tangential-feed type centerless grinding using a surface grinder had been confirmed in the previous workd. In this paper, the performance of the grinding unit in in-feed centerless grinding operation was confirmed, and the effects of the main process parameter, i.e., eccentric angle, on the workpiece roundness was investigated experimentally. The obtained results showed that: (1) the centerless grinding unit performed well in in-feed type centerless grinding; (2) the eccentric angle affects roundness significantly, and its optimal angle is 6°; (3) the workpiece roundness can be further improved by varying the eccentric angle during grinding, and the final roundness reached 0.65 ?m after grinding as the eccentric angle varied from 9° to 6° and to 3°.

Xu, W.; Wu, Y.; Sato, T.; Lin, W.

2011-01-01

354

Performing in-feed type centerless grinding process on a surface grinder  

International Nuclear Information System (INIS)

In our previous study, a new centerless grinding method using surface grinder was proposed. In this method, centerless grinding operations are performed by installing a compact centerless grinding unit, consisting mainly of an ultrasonic elliptic-vibration shoe, a blade and their respective holders, on the worktable of a surface grinder. During grinding, the cylindrical workpiece is held on the ultrasonic shoe and the blade, and its rotational motion is controlled by the elliptic motion of the shoe end-face. An actual unit had been produced and its performance in tangential-feed type centerless grinding using a surface grinder had been confirmed in the previous workd. In this paper, the performance of the grinding unit in in-feed centerless grinding operation was confirmed, and the effects of the main process parameter, i.e., eccentric angle, on the workpiece roundness was investigated experimentally. The obtained results showed that: (1) the centerless grinding unit performed well in in-feed type centerless grinding; (2) the eccentric angle affects roundness significantly, and its optimal angle is 6 deg.; (3) the workpiece roundness can be further improved by varying the eccentric angle during grinding, and the final roundness reached 0.65 ?m after grinding as the eccentric angle varied from 9 deg. to 6 deg. and to 3 deg.

355

The use of Bayesian Networks in Detecting the States of Ventilation Mills in Power Plants  

Directory of Open Access Journals (Sweden)

Full Text Available The main objective of this paper is to present a new method of predictive maintenance which can detect the states of coal grinding mills in thermal power plants using Bayesian networks. Several possible structures of Bayesian networks are proposed for solving this problem and one of them is implemented and tested on an actual system. This method uses acoustic signals and statistical signal pre-processing tools to compute the inputs of the Bayesian network. After that the network is trained and tested using signals measured in the vicinity of the mill in the period of 2 months. The goal of this algorithm is to increase the efficiency of the coal grinding process and reduce the maintenance cost by eliminating the unnecessary maintenance checks of the system.

Sanja Vujnovi?

2014-06-01

356

Measuring the enrichment of fly-ash in cement grinding on the basis of its natural radioactivity  

International Nuclear Information System (INIS)

A method is described for measuring the fly-ash content in different products of cement grinding. This method is based on measuring the natural radioactivity concentrations of the cement components. As fly-ash - originating from coal-fired thermal power stations - contains the radioactive elements of coal in concentrated form, the radioactivity concentration of the fly-ash is higher than that of other cement additives. On the basis of the activity concentrations of cement components, the fly-ash concentrations in different areas of an operating cement ball mill were determined. It was found that the enrichment of fly-ash in the fine fraction-parallel with its impoverishment in the coarse fraction-was not as great as has been supposed because of its smaller particles. (author)

357

Performance analysis of magnesium phosphate cement mortar containing grinding dust  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Magnesium phosphate cement materials are formed by reacting magnesium oxide with water-soluble phosphates such as monoammonium dihydrogen phosphate (ADP), which solidifies at ambient temperature through the formation of hydrated phases in the material. Cylindrical specimens of magnesium phosphate ce [...] ment were molded and varying amounts (0 to 30% weight) of grinding dust were added to the ceramic matrices. The influence of the addition of grinding dust on the characteristics of the mortars in terms of microstructure (SEM), mechanical strength and capillary water absorption was verified. The results obtained proved very satisfactory for the use of this waste as an additive in magnesium phosphate mortars.

Daniel Véras, Ribeiro; Márcio Raymundo, Morelli.

358

Grinding Machine Noise Spectra in Kaduna Metropolis, Nigeria  

Directory of Open Access Journals (Sweden)

Full Text Available When we are exposed to intense noise levels some or all of the hair cells in the organ of corti may be damaged temporarily or permanently. Exposure to excessive noise for a short period of time may produce a loss of heavy sensitivity. Continuous noise exposure over a long period of time (years is more damaging than interrupted exposure to noise, which permits the ear to have a rest and possible recovery period. The presence of low frequency noise in the noise generated by grinding machines in Kaduna metropolis can have adverse effect on concentration and memory.Thus, this study was carried out to assess the grinding machine noice spectra in Kaduna Metropolis using sound level meter (Digital, Testo 816 and Digital Hand Data Logger (DB-525.

Ali Haruna

2011-04-01

359

Developments in Electrical Discharge Grinding process: A review  

Directory of Open Access Journals (Sweden)

Full Text Available Electrical discharge grinding (EDG is a hybrid process involving energy of sparking as well as mechanical grinding. The machining of thin and fragile material is very difficult for manufacturing industries and rapid demand of requirement could not be achieved. Electrical discharge machining is more acceptable machine tool for machining hard and brittle electrically conductive materials but its productivity is very low. In past decade, researchers have focused on EDG for machining these materials because there is no mechanical forces exerted on work piece during machining and it gives better performances than EDM due to the rotating speed of wheel. Therefore, the objective of this paper is to review the array of research works carried out on EDG process. It also focuses on recent developments for practical applications.

Dr. Govindan P*1,

2014-04-01

360

Progress toward a performance based specification for diamond grinding wheels  

Energy Technology Data Exchange (ETDEWEB)

This work sought to improve the communication between users and makers of fine diamond grinding wheels. A promising avenue for this is to formulate a voluntary product standard that comprises performance indicators that bridge the gap between specific user requirements and the details of wheel formulations. We propose a set of performance specifiers of figures-of-merit, that might be assessed by straightforward and traceable testing methods, but do not compromise proprietary information of the wheel user of wheel maker. One such performance indicator might be wheel hardness. In addition we consider technologies that might be required to realize the benefits of optimized grinding wheels. A non-contact wheel-to- workpiece proximity sensor may provide a means of monitoring wheel wear and thus wheel position, for wheels that exhibit high wear rates in exchange for improved surface finish.

Taylor, J.S.; Piscotty, M.S.; Blaedel, K.L.

1996-11-12

 
 
 
 
361

Performance analysis of magnesium phosphate cement mortar containing grinding dust  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Magnesium phosphate cement materials are formed by reacting magnesium oxide with water-soluble phosphates such as monoammonium dihydrogen phosphate (ADP), which solidifies at ambient temperature through the formation of hydrated phases in the material. Cylindrical specimens of magnesium phosphate ce [...] ment were molded and varying amounts (0 to 30% weight) of grinding dust were added to the ceramic matrices. The influence of the addition of grinding dust on the characteristics of the mortars in terms of microstructure (SEM), mechanical strength and capillary water absorption was verified. The results obtained proved very satisfactory for the use of this waste as an additive in magnesium phosphate mortars.

Daniel Véras, Ribeiro; Márcio Raymundo, Morelli.

2009-03-01

362

Tuning Swiss roll metamaterials  

International Nuclear Information System (INIS)

The 'Swiss roll' metamaterial is well suited to operation in the radiofrequency range because it has a low resonant frequency, a strong magnetic response and is electrically very small. However, the elements have to be individually produced, leading to significant variation in the resonant frequency. It is therefore necessary to tune the elements to a target frequency. Three methods for achieving this are described: attaching capacitatively coupled sleeves or discrete capacitors for static tuning, and using a varactor diode to provide electrically controllable tuning. In the last case, the switching time is found to be <1 ms, making dynamic tuning a real possibility.

363

Tuning Swiss roll metamaterials  

Energy Technology Data Exchange (ETDEWEB)

The 'Swiss roll' metamaterial is well suited to operation in the radiofrequency range because it has a low resonant frequency, a strong magnetic response and is electrically very small. However, the elements have to be individually produced, leading to significant variation in the resonant frequency. It is therefore necessary to tune the elements to a target frequency. Three methods for achieving this are described: attaching capacitatively coupled sleeves or discrete capacitors for static tuning, and using a varactor diode to provide electrically controllable tuning. In the last case, the switching time is found to be <1 ms, making dynamic tuning a real possibility.

Wiltshire, M C K, E-mail: michael.wiltshire@imperial.ac.u [Imaging Sciences Department, Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, Ducane Road, London W12 0NN (United Kingdom)

2009-10-21

364

Quantum rolling tachyon  

International Nuclear Information System (INIS)

We consider the quantum treatment of the rolling tachyon background describing the decay of D-branes in the limit of weak string coupling. We focus on the propagation of an open string in the fluctuating background and show how the boundary string action is modified by quantum effects. A bilocal term in the boundary action is generated which, however, does not spoil the vanishing of the ? function at one loop. The propagation of an open string for large times is found to be very strongly suppressed

365

Physical characterization of coffee after roasting and grinding  

Directory of Open Access Journals (Sweden)

Full Text Available Flowability is an important characteristic of handling process for efficiency and reliability purpose of post-harvest operations, which are governed by the physical properties of the product. Physical properties determination is an important factor for formulation of machinery projects and sizing of post-harvest operations, which may impact considerably on the products quality, influencing directly the operation cost and company profit. Thus, the objective of this work was to evaluate and determinate some physical properties (repose angle, unit and bulk density, porosity and color coordinates, particle size, moisture content, water activity, angle of internal friction and effective angle of internal friction of coffee, such as to evaluate the influence of different roast and grinding degrees over these properties. Crude grain coffee (Coffea canephora and Coffea arabica, dehulled and dried were used. These were roasted at two levels: medium light and medium-dark brown, which Agtron numbers are, respectively, SCAA#65 and SCAA#45. After roasting process, grains were grinded at three particle sizes (thin, medium and thick. Both particle size and roast degree significantly affected physical properties of coffee. Coffee samples roasted at medium dark level obtained lower values of moisture content, water activity, repose angle, bulk and real density. Coffee samples grinded at level thin presented an increase of angle of internal friction and effective angle of internal friction, repose angle, bulk and real density, porosity and decrease of water activity values.

Gabriel Henrique Horta de Oliveira

2014-09-01

366

Possibilities of Pelletizing and Briquetting of Dusts from Castings Grinding  

Directory of Open Access Journals (Sweden)

Full Text Available Foundry dust can be divided into three groups: metallic dust with Fe content over 70%, mixed dust with Fe or SiO2 content between 10 –70% and sand wastes with minimum content of SiO2 about 70%. Dust from castings grinding with high Fe content (87.9% is still landfillin Slovakia. The aim of experiments with dust from grinding has been to find the cheapest way of dust agglomeration with minimumamount of binder because of melting in the electric induction furnace. The dust was pelletized and briquetted and as binders bentonite, water glass and cement were used. Briquettes made from dust from grinding with addition of water glass got compression strength after three months on the air about 82 kPa. Briquettes with addition of water glass were melted together with cast iron in electric induction furnace. Yield of metal from briquettes was around 80% and slag quantity around 4% (without briquettes the slag quantity was 1.4%.

A. Pribulová

2010-04-01

367

In-process grinding monitoring through acoustic emission  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english This work aims to investigate the efficiency of digital signal processing tools of acoustic emission signals in order to detect thermal damages in grinding processes. To accomplish such a goal, an experimental work was carried out for 15 runs in a surface grinding machine operating with an aluminum [...] oxide grinding wheel and ABNT 1045 Steel as work material. The acoustic emission signals were acquired from a fixed sensor placed on the workpiece holder. A high sampling rate data acquisition system working at 2.5 MHz was used to collect the raw acoustic emission instead of the root mean square value usually employed. Many statistical analyses have shown to be effective to detect burn, such as the root mean square (RMS), correlation of the AE, constant false alarm rate (CFAR), ratio of power (ROP) and mean-value deviance (MVD). However, the CFAR, ROP, Kurtosis and correlation of the AE have been presented more sensitive than the RMS.

Paulo R., Aguiar; Paulo J. A., Serni; Fábio R. L., Dotto; Eduardo C., Bianchi.

2006-03-01

368

Twin roll casting of magnesium alloys with high aluminum contents  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The purpose of the work is to establish a manufacturing process and technology to facilitate theeconomical manufacture of high-quality magnesium sheet alloys with high aluminum contents, such as AZ61and AZ91. The aim of the work is to establish a twin roll casting technology to facilitate the manufacture ofAZ61 and AZ91 magnesium sheet alloys economically whilst maintaining high quality.Design/methodology/approach: A horizontal type twin roll caster was used to manufacture thin magnesium alloysheets of AZ61 and AZ91. Pair of copper alloy roll and pure copper roll was used for the horizontal type twin roll caster.A closed type tundish was set to the roll caster to keep stable contact of molten magnesium with upper and lower rolls.Findings: The experiment results clarified that AZ61 and AZ91 sheets can be manufactured by twin roll castingprocess. The product sheet thickness in the present experiment is 2.0 to 4.5 mm for AZ91, 2.5 to 5.0mm forAZ61. Mill stiffness and a method of predicting the cast sheet’s thickness were investigated to determine theappropriate manufacturing conditions. The microstructure of AZ61 cast strips was equiaxed structure and thecrystal sizes are different depending on cross section observed. The dendric and equiaxed microstructure wereseen in the microstructure of AZ91 cross section. The intermetllic Mg17Al12 was seen in the grain boundary inAZ91 when roll speed was very slow. The grain size of the manufactured wrought magnesium alloys sheet wasless than 10 micrometers. The obtained magnesium alloy sheet exhibited an equivalent limiting drawing ratio ina warm-drawing test. The limiting drawing ratio of AZ61 was 2.6 and 2.4 for AZ91.Research limitations/implications: The suitable roll speed was from 9m/min to 15m/min in manufacturingAZ91 and AZ61 strip using copper alloy rolls. When in use of pure copper roll, strips were cast between 6m/minand 20m/min for manufacturing AZ61 and AZ91. The superheats in the experiment were 15ºC and 30ºC. Thecast strips should be hot rolled at 300ºC.Originality/value: value In this experiment, it is clarified that AZ61, AZ91 sheets can be manufactured by twinroll casting. These cast sheet can be hot rolled and the manufacturing process by twin roll casting enable tomanufacure thin magnesium sheet alloys with high aluminum contents. It has been found that the manufacturedcast AZ61 and AZ91 have good formability by a warm deep drawing test.

H. Watari

2006-08-01

369

Ground versus steam-rolled barley grain for lactating cows: a clarification into conventional beliefs.  

Science.gov (United States)

Our objective was to compare the effects of grinding versus steam-rolling of barley grain at 30 or 35% of diet dry matter on feed intake, chewing behavior, rumen fermentation, and milk production in high-producing lactating cows. Eight multiparous Holstein cows (85 +/- 9 d in milk) were used in a replicated 4 x 4 Latin square design experiment with four 21-d periods. Each period included 14 d of adaptation and 7 d of sampling. Treatments included grinding (GB) or steam-rolling (SB) of barley grains at either 35 or 30% of dietary dry matter. Diets were prepared as a total mixed ration and delivered twice daily at 0730 and 1600 h. Neither processing method nor dietary barley grain inclusion rate affected dry matter intake, daily eating, ruminating and chewing times, rumen pH and major volatile fatty acid molar percentages, or milk percentages and yields of fat and protein. Energy-corrected milk yield increased for SB compared with GB at 35% but not at 30% barley grain. Feed efficiency was increased by SB, but was unaffected by dietary barley grain level. Results suggest that at 30% dietary barley grain, GB resulted in similar lactation performance as SB and that SB did not affect productivity when dietary barley grain increased from 30 to 35%. Regardless of barley grain level, grinding effectively maintained dry matter intake and rumen pH at 4 h postfeeding, whereas steam-rolling increased feed efficiency. Increasing barley grain from 30 to 35% of diet dry matter did not improve feed intake and milk production. PMID:19528607

Soltani, A; Ghorbani, G R; Alikhani, M; Samie, A; Nikkhah, A

2009-07-01

370

Development of recycling technique of mill reject products using triboelectrostatic separation  

Energy Technology Data Exchange (ETDEWEB)

This study was to develop the triboelectrostatic separation technique to recycle the coal from about 20% of mill reject products remained by grinding process in the coal thermoelectric power plant. In this study, we get a test results that can product the cleaned coal of 15% ash content and 66.23% recovery from mill reject of 47% ash content. And then, from the result of the releases analysis, we proved the excellence of treatment method, after showing the treatment processing which is able to get 80% of recovery of coal from 20% of ash content demanded in the power plant. (author). 8 refs., 2 tabs., 11 figs.

Jeon, Ho-Seok; Shin, Shun-Myung [Korea Institute of Geoscience and Mineral Resources, Taejeon(Korea); Han, Oh-Hyung [Chosun University, Kwangju(Korea); Yoon, Roe-Hoan [Virginia Polytechnic Institute and State University, Blacksburg, VA(United States)

2002-04-30

371

Technological characteristics of creep-feed grinding. Raised cutting forces and reduced work piece temperatures, part 2  

Science.gov (United States)

Temperature measurement during creep feed and oscillating bed grinding and lubrication during deep cut grinding are discussed. A method of determining heat effects on workpiece surface layers during deep cut grinding is outlined. Results indicate that low surface temperatures occur in creep feed and oscillating bed grinding, but very high temperatures are recorded for the intervening regime. The exit velocity of lubricant from the feed nozzle must equal the grinding wheel circumferential velocity to avoid clogging.

Werner, P.; Minke, E.

1982-07-01

372

The influence of the shape of grooves on the behavior of internal material discontinuities in continuous S355J2G3 steel strands during rolling  

Directory of Open Access Journals (Sweden)

Full Text Available The article discusses problems related to the influence of rolling processes on the process of closing of internal discontinuities in continuous castings during rolling in shape grooves. Numerical modelling of the process of rolling 160 × 160 mm continuous S355J2G3 steel strands was carried out using the Forge 2008R software program. The experimental studies were conducted in a D150 laboratory rolling mill. Holes simulating material discontinuities were examined. In numerical and experimental studies, in steel samples after rolling in the third rolling stand, the defects were closing in 100 % on average. It was stated that the speed of closing of material discontinuities in feedstock is strongly influenced by the shape of the rolling groove.

H. Dyja

2014-10-01

373

Investigations upon the indefinite rolls quality assurance in multiple regression analysis  

International Nuclear Information System (INIS)

The rolling rolls quality has been enhanced mainly due to the improvements of the chemical compositions of rolls materials. The realization of an optimal chemical composition can constitute a technical efficient mode to assure the exploitation properties, the material from which the rolling mills rolls are manufactured having a higher importance in this sense. This paper continues to present the scientifically results of our experimental research in the area of the rolling rolls. The basic research contains concrete elements of immediate practical utilities in the metallurgical enterprises, for the quality improvements of rolls, having in last as the aim the durability growth and the safety in exploitation. This paper presents an analysis of the chemical composition, the influences upon the mechanical properties of the indefinite cast iron rolls. We present some mathematical correlations and graphical interpretations between the hardness (on the working surface and on necks) and the chemical composition. Using the double and triple correlations which is really helpful in the foundry practice, as it allows us to determine variation boundaries for the chemical composition, in view the obtaining the optimal values of the hardness. We suggest a mathematical interpretation of the influence of the chemical composition over the hardness of these indefinite rolling rolls. In this sense we use the multiple regression analysis which can be an important statistical tool for the investigation of relationships between variables. The enunciation of some mathematically modeling results can be described through a number of multi-component equations determined for the spaces with 3 and 4 dimensions. Also, the regression surfaces, curves of levels and volumes of variations can be represented and interpreted by technologists considering these as correlation diagrams between the analyzed variables. In this sense, these researches results can be used in the engineers collectives of the foundries and the rolling mills sectors, for quality assurances of rolls as far back as phase of production, as well as in exploitation of these, what lead to, inevitably, to the quality assurance of produced laminates. (Author) 16 refs.

374

Rolling friction of adhesive microspheres  

Science.gov (United States)

The rolling friction of adhesive microspheres is an important quantity as it determines the strength and stability of larger aggregates. Current models predict rolling forces that are 1 to 2 orders of magnitude smaller than observed experimentally. Starting from the well-known Johnson-Kendall-Roberts (JKR) contact description, we derive an analytical theory for the rolling friction based on the concept of adhesion hysteresis, e.g. a difference in apparent surface energies for opening/closing cracks. We show how adhesion hysteresis causes the pressure distribution within the contact to become asymmetrical, leading to an opposing torque. Analytical expressions are derived relating the size of the hysteresis, the rolling torque, and the rolling displacement, ?. We confirm the existence of a critical rolling displacement for the onset of rolling, the size of which is set by the amount of adhesion hysteresis and the size of the contact area. We demonstrate how the developed theory is able to explain the large rolling forces and particle-size dependence observed experimentally. Good agreement with experimental results is achieved for adhesion hysteresis values of (??/?) ? 3 for polystyrene, and (??/?) ? 0.5 for silicates, at crack propagation rates of 0.1 µm s-1 and 1-10 µm s-1, respectively.

Krijt, S.; Dominik, C.; Tielens, A. G. G. M.

2014-04-01

375

Changes of texture and mechanical properties in sheet thickness for rolled low-alloy chromium  

International Nuclear Information System (INIS)

Distribution of texture and mechanical properties by sheet thickness of low-alloy of Cr-V-Y-B system rolled in the 700-1100 deg C temperature range with total 75-80% reduction has been investigated. Methods of pole figures, electron microscopy measurements of microhardness and bend test have been applied. Subsurface hardened layer with increased temperature of cold brittleness and a layer with anomalous crystallographical texture have been disclosed. Reduction of rolling temperature is shown to increase width of the embrittled layer. Formation of subsurface layers is associated with existence of the zone of difficult deformation in the point of contact with rolls of the rolling mill. Strong effect on hardening is produced by boron redistribution with growth of segregation near crystal defects

376

Measurement system of the transverse temperature profile of hot rolled strip  

International Nuclear Information System (INIS)

Output and cost efficiency in the production of hot-rolled strip depend to a large content on the uniformity of geometric and mechanical properties over the length and width of the rolled end product. To ensure the homogeneous temperatures required for this during the rolling process a system to measure and evaluate the transverse temperature profile was developed and implemented in production. The systems used consist of temperature scanners and computers for measurement and data evaluation. The systems have been installed in Kwangyang hot strip mills, in the cases at the exit of the finishing train and at the entry of the coiler. They are used in production to determine the effect of the finishing train and the cooling zone on the technological properties of the hot rolled strip

377

FE analysis of dynamic characteristics for mill's liners  

Science.gov (United States)

Slab side pressing is an online regulation width technology for continuous casting slab, the liner at the bottom of the framework under the larger impact force, it often can occurrence accident of liner Board broken during working of sizing press rolling mill. In order to analyze force distribution and its peak in the liner of rolling mill during side pressing, liner dynamics model is established using nonlinear function of finite element software, and the contact mode is established for liner and wheel by Hertz law theory. It yields the relations between maximal stress and tap hole in the liner, the design scheme is extracted for improving condition of linerboard's stress, and the calculated results were much inosculated with the measured values. The studied results indicated that the liner's life gets improve obviously in field.

Feng, Xianzhang; Cui, Yanmei; Jiang, Zhiqiang; Hou, Tao

2009-07-01

378

Development of industrial production of ultrafine grained steel in tandem hot strip mill; Production industrielle d'acier a grain ultra-fin au train a bandes  

Energy Technology Data Exchange (ETDEWEB)

Based on a model of microstructure evolution, an appropriate rolling schedule has been worked out to produce ultrafine grained steel (2 to 5 {mu}m) on the hot strip mill. This rolling schedule is characterized by a large reduction in the finishers followed by strong cooling. Implementing such a rolling schedule on a conventional HSM raises major problems: increased rolling torque and force, lowered crown and shape control, disturbed looper control, accelerated roll damage, increased slip between strip and roll, insufficient cooling efficiency. These problems have been solved on the new Nakayama HSM by introducing innovative processes such as: single roll drive with different diameter and a new CVC, curtain wall cooling in the finisher, low inertia hydraulic looper, new high-speed steel rolls with solid lubrication. (authors)

Kurahashi, R.; Hakomori, K.; Chikushi, I.; Morimoto, T. [Nakayama Steel Works, Ltd. (Japan); Yanagimoto, J. [Tokyo Univ. (Japan); Takaoka, S. [Kawasaki Heavy Industries Ltd., Kobe (Japan)

2005-04-01

379

Structural transformations in 12Kh2N4A steel during band grinding  

International Nuclear Information System (INIS)

Studied is the effect of contact temperatures in the grinding zone during the treatment with abrasive bands on the phase transformations in surface layers of carburized parts of the 12Kh2N4A steel. The phase analysis has been made and microhardness has been measured. It has been found that maximum contact temperatures are two times lower during band grinding than during grinding with a hard abrasive disk. Considerable changes in phase constitution of a surface layer appear at the increase of the temperature in the grinding zone. The band grinding of the 12Kh2N4A steel parts is recommended to perform at the grinding zone temperature not higher than 200-300 deg C

380

Analysis of the performance of superabrasive and alumina grinding wheels with different bonds and machining conditions  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a review of researches on CBN (cubic boron nitride grinding wheels with the purpose of identifying the state of art in abrasive machining and serving as the basis for future researches and laboratory tests. The scientific studies investigated here report on interesting results involving grinding, published by Brazilian and foreign authors. The methods and the results are presented and discussed. In addition, a grinding setup is presented which provides more reliable experimental results about the surface integrity of fragile materials. This setup was obtained for grinding tests in several grinding conditions during the wheel service life, using alumina and vitrified and resin bond CBN grinding wheels. Results of cutting force, surface roughness and G ratio are also presented and discussed. They confirm the excellent machining capacity of the CBN wheel, with stable behavior in cutting force and roughness results during the tests. The G ratio values are in agreement with the results found by other researchers.

Eduardo Carlos Bianchi

2003-06-01

 
 
 
 
381

Machining mode and error analysis in non-axisymmetric aspheric surface grinding  

Science.gov (United States)

To improve machining accuracy of non-axisymmetric lens, this paper presents the grinding mode with equal arc length feeding in parallel grinding, and analyses the relations between machining error and machining step in both equal length mode and equal arc length mode. For the same purpose, this paper also discusses the calculation of 2-axis machining path compared with 3-axis machining. Finally, the calculation and simulation of machining path are carried out to guide practical grinding.

Wang, Zhen-zhong; Guo, Yin-biao; Huang, Hao; Gou, Jiang

2007-12-01

382

Cylindrical grinding of SiC particles reinforced aluminium metal matrix composites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper deals with an experimental study on the grindability of Al/SiC metal matrix composites in cylindrical grinding. Machining of metal matrix composites (MMCs) is an area to be focused and finishing processes such as grinding to obtain a good surface finish and damage-free surfaces are crucial for the application of these materials. Nevertheless, grinding of MMCs has received little attention so far, thereby a detailed study on that has been carried out. In the present work, experimen...

Thiagarajan, C.; Sivaramakrishnan, R.; Somasundaram, S.

2011-01-01

383

Effect of Cooling Environment on Grinding Performance of Nickel Based Superalloy Inconel 718  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The study presents the experimental investigation of surface grinding of superalloy Inconel 718. The grinding performance in terms of grinding force, surface roughness and surface topography were examined by conducting statistical experiments. The parameters that have been chosen as control factors are: table speed, infeed, grit size and the type of lubricant. An L27 orthogonal array experiments were conducted. The results show that the grit size and infeed are the most signi...

Pawade, Raju S.; Arvind Chavan; Pankaj Chitalkar; Sandeep Huddedar

2012-01-01

384

Phase transformation of single crystal silicon induced by grinding with ultrafine diamond grits  

International Nuclear Information System (INIS)

Phase transformation of single crystal silicon (Si) was investigated under various grinding conditions using high-resolution transmission electron microscopy. Nanocrystals with sizes ranging from 6 to 20 nm of diamond cubic silicon (Si-I) and high-pressure phase (Si-III) were observed in the grinding-induced amorphous Si layers. The phase transformation pattern was found to be influenced by the thermal status involved in the grinding processes.

385

Strength and power determinants of grinding performance in America's Cup sailors.  

Science.gov (United States)

The purpose grinding is a physically demanding component of America's Cup sailing that is important to overall team performance, but little research is available on the determinants of grinding performance. We examined the relationship between various measures of muscular performance and the performance of upper-body grinding. Eleven elite male America's Cup sailors (33.9 +/- 5.5 yr, 97.8 +/- 12.5 kg, 186.0 +/- 7.1 cm) who performed grinding as part of their on-board role with extensive strength training experience participated in this study. Muscular performance testing examined the force, velocity, and power capabilities of the upper-body musculature, with upper-body push (bench press) and pull (bench pull) movements performed across loads of 10-100% of 1 repetition maximum (1RM). Functional grinding performance was examined for both forward and backward grinding and at 2 different resistances (moderate = 48 N x m, heavy = 68 N x m) using a land-based ergometer. Bench press 1RM and maximum force capability were the measures demonstrating the strongest correlation with forward grinding performance (r = 0.88-0.99 and 0.87-0.99, respectively), with the relationship increasing with grinding load. For backward grinding, there was a very strong relationship with bench pull maximum power (r = 0.85-0.98) in addition to 1RM (r = 0.90-0.95) and maximum force (r = 0.87-0.95). It appears that although maximal strength is a crucial muscular performance characteristic for grinding performance in all conditions, for backward grinding, there is the additional need to focus on the development of speed strength/power to maximize performance gains. This information was used by the Emirates Team New Zealand physical conditioner to develop a conditioning intervention to help improve grinding performance. PMID:19675468

Pearson, Simon N; Hume, Patria A; Cronin, John B; Slyfield, David

2009-09-01

386

Determination of the relative position between grinding wheel and a cylindrical workpiece on a 7 axis grinding machine by acoustic emission  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The contact between grinding wheel and workpiece in the grinding process is recognized by acoustic emission (AE). Two acoustic emission monitoring systems (MS) were integrated into a 3 axis CNC grinding machine. A laptop allows the signal acquisition and visualization. The acquired AE RMS signals fr [...] om the contact between tool and workpiece are analyzed permitting to establish the most suitable AE monitoring system to recognize the contact in a particular grinding machine. In a second experimental setup the selected MS was installed on a 7 axis tool grinding machine at an industrial partner. At this partner, the relative position between grinding wheel and workpiece was previously determined manually. This procedure has a direct influence on the results depending on the technical skills of the operator. The automation of this activity supported by acoustic emission has led to satisfactory results regarding the relative position between grinding wheel and workpiece and contributed to the setup time reduction.

Walter Lindolfo, Weingaertner; Adriano, Boaron.

387

Determination of the relative position between grinding wheel and a cylindrical workpiece on a 7 axis grinding machine by acoustic emission  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The contact between grinding wheel and workpiece in the grinding process is recognized by acoustic emission (AE). Two acoustic emission monitoring systems (MS) were integrated into a 3 axis CNC grinding machine. A laptop allows the signal acquisition and visualization. The acquired AE RMS signals fr [...] om the contact between tool and workpiece are analyzed permitting to establish the most suitable AE monitoring system to recognize the contact in a particular grinding machine. In a second experimental setup the selected MS was installed on a 7 axis tool grinding machine at an industrial partner. At this partner, the relative position between grinding wheel and workpiece was previously determined manually. This procedure has a direct influence on the results depending on the technical skills of the operator. The automation of this activity supported by acoustic emission has led to satisfactory results regarding the relative position between grinding wheel and workpiece and contributed to the setup time reduction.

Walter Lindolfo, Weingaertner; Adriano, Boaron.

2012-03-01

388

Evaluation of minimum quantity lubrication grinding with nano-particles and recent related patents.  

Science.gov (United States)

In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques that can significantly improve both environmentally conscious and energy saving and costeffective sustainable grinding fluid alternatives. Among them, one patent is about a supply system for the grinding fluid in nano-particle jet MQL, which produced MQL lubricant by adding solid nano-particles in degradable grinding fluid. The MQL supply device turns the lubricant to the pulse drops with fixed pressure, unchanged pulse frequency and the same drop diameter. The drops will be produced and injected in the grinding zone in the form of jet flow under high pressure gas and air seal. As people become increasingly demanding on our environment, minimum quantity lubrication has been widely used in the grinding and processing. Yet, it presents the defect of insufficient cooling performance, which confines its development. To improve the heat transfer efficiency of MQL, nano-particles of a certain mass fraction can be added in the minimum quantity of lubricant oil, which concomitantly will improve the lubrication effects in the processing. In this study, the grinding experiment corroborated the effect of nano-particles in surface grinding. In addition, compared with other forms of lubrication, the results presented that the grinding force, the friction coefficient and specific grinding energy of MQL grinding have been significantly weakened, while G ratio greatly rose. These are attributed to the friction oil-film with excellent anti-friction and anti-wear performance, which is generated nano-particles at the wheel/workpiece interface. In this research, the cooling performance of nano-particle jet MQL was analyzed. Based on tests and experiments, the surface temperature was assayed from different methods, including flood lubricating oil, dry grinding, MQL grinding and nano-particle jet MQL grinding. Because of the outstanding heat transfer performance of nano-particles, the ratio of heat delivered by grinding media was increased, leading to lower temperature in the grinding zone. Results demonstrate that nano-particle jet MQL has satisfactory cooling performance as well as a promising future of extensive application. PMID:23763268

Li, Changhe; Wang, Sheng; Zhang, Qiang; Jia, Dongzhou

2013-06-01

389

Profile Grinding of High-Speed Steel using Ultrafine-Crystalline cBN Wheels  

Science.gov (United States)

This paper deals with the grinding characteristics of newly developed ultrafine-crystalline cBN (cBN-U) abrasive grains in creep feed profile grinding of high-speed steels. Experiments for producing a V-shaped groove on a flat surface in one pass by creep feed grinding have been carried out using new polycrystalline cBN-U and representative conventional cBN (cBN-B) abrasive grains. When grinding with the cBN-U wheel, both radial wear and profile wear are less, and hence the grinding ratio is around 4 times higher than that with conventional cBN-B wheel. Grinding force in grinding with the cBN-U wheel is reduced by 5˜15 % compared with that in grinding with the cBN-B wheel. The cBN-U abrasive grain is suitable for application with a high dimensional accuracy in creep feed profile grinding for high-speed steel, because it gives less profile wear, and hence better form retention of the wheel, than conventional cBN abrasive grain.

Ichida, Yoshio

390

Profile Grinding of Superalloys with Ultrafine-Crystalline cBN Wheels  

Science.gov (United States)

This paper deals with the grinding characteristics of newly developed polycrystalline cBN (cBN-U) abrasives in creep feed profile grinding of nickel-based superalloys. Experiments for producing a V-shaped groove on a flat surface in one pass by creep feed grinding have been carried out using the new polycrystalline cBN-U and representative conventional cBN (cBN-B) grits. When grinding with cBN-U abrasives, both radial wear and profile wear are less, and hence the grinding ratio is around 10 times higher than that with the conventional cBN-B abrasives. Grinding forces in grinding with cBN-U abrasives are reduced by 20-30% compared with those in Grinding with cBN-B abrasives. The cBN-U abrasive is suitable for the applications with a high dimensional accuracy in creep feed profile grinding for nickel-based superalloys, because it gives less profile wear, and hence better form retention, than conventional cBN abrasive.

Ichida, Yoshio; Sato, Ryunosuke; Morimoto, Yoshitaka; Inoue, Yoshihiro

391

New Abrasive Materials and Their Influence on the Surface Quality of Bearing Steel After Grinding  

Directory of Open Access Journals (Sweden)

Full Text Available This paper focuses on the influence of various types of abrasive grains on cutting properties during the grinding process for bearing steel. In this experiment, not only conventional super-hard abrasive materials but also a new type of abrasive material were employed in grinding wheels. The measurement results were compared, and an evaluation was made of the cutting properties of the new abrasive material. The options were then evaluated for their practical applicability. The measurement results indicated that a grinding wheel with Abral and SG grains is the most suitable for grinding hardened bearing steel in order to achieve the best roughness and geometrical accuracy.

Ondrej Jusko

2012-01-01

392

Imaging subsurface damage of grinded fused silica optics by confocal fluorescence microscopy  

International Nuclear Information System (INIS)

We report an experimental investigation of fluorescence confocal microscopy as a tool to measure subsurface damage on grinded fused silica optics. Confocal fluorescence microscopy was performed with an excitation at the wavelength of 405 nm on fixed abrasive diamond grinded fused silica samples. We detail the measured fluorescence spectrums and compare them to those of oil based coolants and grinding slurries. We evidence that oil based coolant used in diamond grinding induces a fluorescence that marks the subsurface damages and eases its observation. Such residual traces might also be involved in the laser damage process. (authors)

393

Mathematical models of homochiralisation by grinding of crystals  

CERN Document Server

We review the existing mathematical models which describe physicochemical mechanisms capable of producing a symmetry-breaking transition to a state in which one chirality dominates the other. A new model is proposed, with the aim of elucidating the fundamental processes at work in the crystal grinding systems of Viedma [Phys Rev Lett 94, 065504, (2005)] and Noorduin [J Am Chem Soc 130, 1158, (2008)]. We simplify the model as far as possible to uncover the fundamental competitive process which causes the symmetry-breaking, and analyse other simplifications which might be expected to show symmetry-breaking.

Wattis, Jonathan AD

2010-01-01

394

Mathematical Models of the Homochiralisation of Crystals by Grinding  

Science.gov (United States)

We review the existing mathematical models which describe physicochemical mechanisms capable of producing a symmetry-breaking transition to a state in which one chirality dominates the other. A new model is proposed, with the aim of elucidating the fundamental processes at work in the crystal grinding systems of Viedma (Phys Rev Lett 94:065504, 2005) and Noorduin (J Am Chem Soc 130:1158-1159, 2008). We simplify the model as far as possible to uncover the fundamental competitive process which causes the symmetry-breaking, and analyse other simplifications which might be expected to show symmetry-breaking.

Wattis, Jonathan A. D.

2011-04-01

395

Rolling tool calibration for cold rolling of tubes  

International Nuclear Information System (INIS)

An analysis was made of calibration methods for step-back rolling of tubes from austenitic steels to meet the order of nuclear power for tubes with a high quality of inner surfaces. On the basis of this analysis the optimization criterion chosen was the observance of the constant value of the ratio of wall thickness deformation to the deformation of tube diameter for any length of a tube. A logarithmic function was derived for the shape of the rolling pin. Operating trials showed that rolling instruments of the given design have a favourable effect on the quality of the inner surface of tubes and on the even load of the rolling system in an operating cycle. (Ha)

396

Production of normalized steel plate through normalizing rolling; Producao de chapas grossas normalizadas diretamente do calor de laminacao  

Energy Technology Data Exchange (ETDEWEB)

Normalized plates can be got directly from the rolling heat through the use of a normalizing rolling process. In such way, an additional step of the conventional process of production of normalized plates - the normalizing heat treatment - can be suppressed, reducing the manufacturing cost of the product and shortening its production time. This relatively new production route is being used in several steelworks all over the world for many years. This work describes the implementation trials of normalizing rolling at COSIPA`s plate mill, using an alternative process of controlled rolling called recrystallization controlled rolling. The results got with new technique were successful, as it was able to produce plates with properties very similar to the conventionally normalized material, attending the requirements of the DIN 17100 RR 52-3N standard. This is one of many standards that permit the use of this new route of normalized steel plate production. (author) 14 refs., 8 figs., 2 tabs.

Gorni, Antonio Augusto; Cavalcanti, Celso Gomes; Reis, Jackson Soares de Souza; Silveira, Jose Herbert Dolabela da [Companhia Siderurgica Paulista (COSIPA), SP (Brazil)

1997-12-31

397

Microstructure and temperature monitoring during the hot rolling of AZ31  

Science.gov (United States)

This study details the microstructural evolution during hot rolling of AZ31 alloy sheet using a pilot-scale rolling mill. The aim is to understand the deformation mechanisms leading to grain refinement under industrial processing conditions and to design and optimize the hot rolling schedule for AZ31 in order to produce sheet with a fine and homogeneous microstructure. The study examined three different hot rolling temperatures, 350, 400, and 450°C, and two rolling speeds, 20 and 50 rpm. A total thickness reduction of 67% was obtained using multiple passes, with reductions of either 15% or 30% per pass. It was found that the microstructure of the AZ31 alloy was sensitive to the rolling temperature, the reduction (i.e., strain) per pass and the rolling speed (i.e., strain rate). The results show that the large cast grain structure is broken down by segmentation of the cast grain through localized deformation in twin bands, where dynamic recrystallization occurs in these bands as well as at the grain boundaries (necklacing).

Essadiqi, E.; Shehata, M. T.; Javaid, A.; Galvani, C.; Shen, G.; Yue, S.; Verma, R.

2009-08-01

398

Mill’s Liberal Feminism: Its Legacy and Current Criticism  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper highlights John Stuart Mill’s views on the problem of gender equality as expressed in The Subjection of Women, which is commonly regarded as one of the core texts of Enlightenment liberal feminism of the 19th century. In this paper, the author outlines the historical context of both Mill’s views and his personal biography, which influenced his argumentation for the emancipation of women, and considers Mill’s utilitarianism and liberalism, as the main philosophical background ...

MARIANA SZAPUOVÁ

2006-01-01

399

Nonlinear Observers for Parametric Roll  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Parametric roll resonance is a dangerous resonance phenomenon affecting several kinds of ships, such as cruise ships, fishing vessels and container ships. In a worst case scenario parametric roll resonance may lead to roll angles of up to 50 degrees, capsizing of the vessel, or damage of goods and ship for tens of millions of dollars, citep{Ginsberg1998}.Accurate equations in the model for the ship motion are important because they are directly related to the observer design. There has been d...

Olsen, Gunnhild Konstanse Hoff

2012-01-01

400

In-process EDM truing to generate complex contours on metal-bond, superabrasive grinding wheels for precision grinding structural ceramics  

International Nuclear Information System (INIS)

The demand and use of precision grinding of structural ceramics continue to increase as the worldwide advanced ceramic industry surpasses $20 billion is sales. Included in this industry are engineering structural ceramics, electronic ceramics, bioceramics and others. These materials are used in applications such as engine components, casting and extrusion dies, bearings, medical implants, nozzles, thermal insulators, and more. Along with the variety of ceramic applications comes a broad range of precision requirements, which in turn leads to various required processes to accommodate a spectrum of specifications. A process for grinding ceramic components to micrometer tolerances was employed and further developed at Lawrence Livermore National Laboratory for two separate grinding projects

 
 
 
 
401

Failure Analysis of Rollers in mill stand using Failure mode Effect Analysis  

Directory of Open Access Journals (Sweden)

Full Text Available Rolling is an important steel production process. Productivity and quality improvements in metal rolling are possible by paying a detailed attention to the various roll failure modes.A proper understanding of the causes of roll failure modes is usually complex and depends on the metallurgical quality of rolls, improper mill usage practices and abnormal rolling conditions. The work rolls operate under severe condition and should posses excellent wear resistance and very little plastic deformation to withstand mechanical and thermal shocks. The objective of this study is to analyze different failures associated with rollers in the mill stand using Failure Mode Effect Analysis (FMEA. The values of severity, probability of occurrence and detection of each failure mode are taken according to the FMEA criteria and based on these values, Risk Priority Number of each failure mode is calculated. Based on the risk levels of each failure modes, remedies for the respective failure modes are presented. Thus it results in reduced risk of process failure, improved reliability and quality of the products.

Tadisetti Premsai

2014-07-01

402

Optimal Cluster Mill Pass Scheduling With an Accurate and Rapid New Strip Crown Model  

International Nuclear Information System (INIS)

Besides the requirement to roll coiled sheet at high levels of productivity, the optimal pass scheduling of cluster-type reversing cold mills presents the added challenge of assigning mill parameters that facilitate the best possible strip flatness. The pressures of intense global competition, and the requirements for increasingly thinner, higher quality specialty sheet products that are more difficult to roll, continue to force metal producers to commission innovative flatness-control technologies. This means that during the on-line computerized set-up of rolling mills, the mathematical model should not only determine the minimum total number of passes and maximum rolling speed, it should simultaneously optimize the pass-schedule so that desired flatness is assured, either by manual or automated means. In many cases today, however, on-line prediction of strip crown and corresponding flatness for the complex cluster-type rolling mills is typically addressed either by trial and error, by approximate deflection models for equivalent vertical roll-stacks, or by non-physical pattern recognition style models. The abundance of the aforementioned methods is largely due to the complexity of cluster-type mill configurations and the lack of deflection models with sufficient accuracy and speed for on-line use. Without adequate assignment of the pass-schedule set-up parameters, it may be difficult or impossible to achieve the required strip flatness. In this paper, we demonstrate optimization of cluster mill pass-schedules using a new accurate and rapid strip crown model. This pass-schedule optimization includes computations of the predicted strip thickness profile to validate mathematical constraints. In contrast to many of the existing methods for on-line prediction of strip crown and flatness on cluster mills, the demonstrated method requires minimal prior tuning and no extensive training with collected mill data. To rapidly and accurately solve the multi-contact problem and predict the strip crown, a new customized semi-analytical modeling technique that couples the Finite Element Method (FEM) with classical solid mechanics was developed to model the deflection of the rolls and strip while under load. The technique employed offers several important advantages over traditional methods to calculate strip crown, including continuity of elastic foundations, non-iterative solution when using predetermined foundation moduli, continuous third-order displacement fields, simple stress-field determination, and a comparatively faster solution time