• Title/Summary/Keyword: Rolling Up

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Control Scheme Using Forward Slip for a Multi-stand Hot Strip Rolling Mill

  • Moon, Young-Hoon;Jo, I-Seok;Chester J. Van Tyne
    • Journal of Mechanical Science and Technology
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    • v.18 no.6
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    • pp.972-978
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    • 2004
  • Forward slip is an important parameter often used in rolling-speed control models for tandem hot strip rolling mills. In a hot strip mill, on-line measurement of strip speed is inherently very difficult. Therefore, for the set-up of the finishing mill, a forward slip model is used to calculate the strip speed from roll circumferential velocity at each mill stand. Due to its complexity, most previous researches have used semi-empirical methods in determining values for the forward slip. Although these investigations may be useful in process design and control, they do not have a theoretical basis. In the present study, a better forward slip model has been developed, which provides for a better set-up and more precise control of the mill. Factors such as neutral point, friction coefficient, width spread, shape of deformation zone in the roll bite are incorporated into the model. Implementation of the new forward slip model for the control of a 7-stand hot strip tandem rolling mill shows significant improvement in roll speed set-up accuracy.

Rolling Stock Fire Engineering aspect of System Engineering (System Engineering 측면에서 전동차 화재기술관리)

  • Chang, Jung-Hoon;Kang, Chan-Yong
    • Proceedings of the KSR Conference
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    • 2005.05a
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    • pp.163-168
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    • 2005
  • In case of rolling stock, SEMS is generally applied in the advanced countries, but is start stage in our country. SEMS is defined the system engineering management system in order to achieve the optimized train performance among the several client requirements aspect of technical engineering management during the design life cycle. And the fire engineering activities in hong kong EMU project are introduced aspect of SEMS in this paper. The fire engineering at rolling stock in view of SEMS controls to apply the satisfied interior material by the fire safety standards (regulation of the commute urban subway safety guideline by the MOCT, BS 6853, NFPA 130, NF F 16-101) and to minimize the fire load in order that passengers egress safe from the fired rolling stock. The rolling stock in the advanced countries is designed to stand for 15-20 minutes in considering the rolling stock to be fired in tunnel. For passenger fire safety, the passenger evacuation provision and progress is set up.

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Application of New AGC to the Cold Rolling Mills of Pohand Works ((포항)냉연 New AGC 적용기술)

  • 김철종;이동섭;박남수
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.08a
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    • pp.150-157
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    • 1999
  • As the customer demands thickness quality stricter, new techniques of automatic thickness control(AGC), is adopted to continuous cold rolling mills. The cold rolling mills of Pohang Works have revamped the existing conventional AGC system that control the thickness at all-stands automatically by the mass flow AGC based on the measurement of strip-speed and thickness between mill stands. The No. 2 Cold Rolling Mill be has adopted the New AGC system since Oct. 1995, and The No.1 Cold Rolling Mill since June. 1999. Thanks to the New AGC system, precise control of thickness is possible not only at constant rolling speed region, but also during line speed up and down. This report describes application techniques of the New AGC system and performance of the system.

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Effect of process parameters on propagation of edge crack in the cold rolling (냉간 박판압연공정에서 공정변수가 엣지 크랙 성장에 미치는 영향)

  • Cui, Xiang Zi;Lee, S.H.;Lee, S.J.;Lee, J.B.;KIm, B.M.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.405-408
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    • 2009
  • Edge cracks in cold rolling always influence to the quality of productions, while the "V" shaped cracks were propagated by passing the roll gap. We set up the sizes and shapes of initial cracks in simulation according to the references from real productions. Different to in hot rolling, the cracks in cold rolling couldn't be reduced from propagation automatically after generated, even if these could be reduced by changing the process parameters. In this paper, we described the affections of process parameters on the propagation of edge cracks, such as reduction ratio and tension. We predicted that the dependence of the cracks propagations of changing of process conditions and expected to gain the smaller edge cracks. By raising the reduction ratio, the cracks were propagated increasingly in both transverse and rolling directions. And as tension raise, the cracks became propagated in both directions in which transverse direction was less effectively.

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A Study on the Development of Hot Rolling Process for 18Cr-10Mn-0.44N2 (18Cr-10Mn-0.44N2 고질소강의 열연공정개발에 관한 연구)

  • Kim, Y.D.;Cho, J.R.;Lee, J.W.;Bae, W.B.
    • Transactions of Materials Processing
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    • v.20 no.4
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    • pp.296-302
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    • 2011
  • The objective of this paper is to determine the effect of process parameters on the behavior of a 18Cr-10Mn-$0.44N_2$ nitrogen steel sample deformed by hot rolling. Compression tests were carried out at high temperatures to determine the flow stresses needed for a finite element(FE) analysis. The strain rate, ranging from 0.1 to $1.0s^{-1}$, significantly affected the flow stress at temperatures higher than $1,000^{\circ}C$. Non-isothermal rolling simulations and laboratory rolling tests were performed with plate specimens 14.5mm thick, 135mm wide and 226mm long. A rolling reduction of 15% per pass leading to a cumulative rolling reduction of 60% was determined as optimal. The extension ratio of 176.5% in the length direction was about 30.4 times greater than the extension ratio of 5.8% in the width direction. Isotropic properties for tensile strength, microstructure and grain size were measured after mock-up hot rolling tests. The results from the mockup tests were found to be in good agreement with those of the simulations.

A study on the function and application of the glasses for rolling stock (철도차량용 유리의 기능 및 적용성에 관한 연구)

  • Chang, Dae-Sung;Lee, Heung-Jae
    • Proceedings of the KSR Conference
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    • 2011.05a
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    • pp.1097-1108
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    • 2011
  • In this paper, the area which some glasses of railway vehicle are applied to and the function & requirements of each glass would be studied, a sort of glass & up to date glasses and design propriety of railway vehicle's glasses were also researched. And then the feasible application of up to date glasses for next developing rolling stock was studied.

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A study on Characteristics of Disc Brake of & Technology of Brake Control System in High Speed Railway (고속차량용 디스크 제동 특성 및 제동제어 방법기술에 대한 연구)

  • Shin Y.J;Choi K.J.;Gwak J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.393-397
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    • 2005
  • Since the braking system of rolling stock is directly linked to it's safety, ensuring reliability of braking system and evaluation of performance of it are very important. To develope the performance of braking system, it is required advanced technology and gradually various factors in the field test result. This study is designed to analyze the air pressure control about braking force in rolling stock, also, by comparing braking force of high speed railway with that of high speed train. This paper suggests to establish a method of computation of braking force form the air pressure control. And The high speed train researches into patterns of braking system such as the train of speed up and introduction of electric and pneumatic braking system.

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A Study on Reducing Speed Control of Hydraulic Motor of Textiles Supply Rolling Equipment (섬유공급 롤링장치의 유압모터 감속도 제어에 관한 연구)

  • 이재구;김도태;김성동
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.10a
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    • pp.62-67
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    • 2001
  • The textiles supply rolling equipment is a part of inspection machine which inspect finished textiles and it check up textiles through rolling hydraulic equipment. This study suggests a method to select the capacity and initial gas pressure of accumulator to control reducing speed of the hydraulic motor to a desired degree. An accumulator in hydraulic systems is hydraulic machinery which stores kinetic energy of inertia body during braking. A series of computer simulations were done for the brake action and the selection method was based upon a trial and error approach. The results of the simulation work were compared with those of experiments and these results show that the proposed method can be applied effectively to control reducing speed of the hydraulic motor when braking action in textiles rolling system.

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Design of Rolling Path Schedule for Refinement of Austenite Grain (오스테나이트 결정립 미세화를 위한 후판 압연 패스 스케줄의 설계)

  • Hong, Chang-Pyo;Park, Jong-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.11
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    • pp.1844-1853
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    • 2001
  • In the present investigation, it was attempted to design the rolling pass schedule fur a clean steel of 0.1C-1.5Mn-0.25Si with the objective of the austenite grain refinement. As the method of approach, a coupled mathematical modeling technique was proposed which consists of a recrystallization model and a flow stress modes. The validity of the coupled model was examined through comparison with results of continuous and discontinuous compression tests at various temperatures, strains and strain rates. The coupled model was incorporated with the finite element method to set up a systematic design methodology far the rolling path schedule for austenite grain refinement. Two path schedules were obtained and discussed in the paper with regard to rolling path time, average grain size, grain size deviation in thickness, etc.

Rolling Fatigue Life of Silicon Nitride Ceramic Balls (질화규소 세라믹볼의 구름피로수명)

  • 최인혁;박창남;최헌진;이준근;신동우
    • Tribology and Lubricants
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    • v.15 no.2
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    • pp.150-155
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    • 1999
  • The rolling fatigue lives (RFL) of five kinds of silicon nitride balls were investigated. Four kinds of Si$_3$N$_4$balls were fabricated using different raw materials, sintering aids and sintering conditions. Commercially available Si$_3$N$_4$ball was also studied for comparison. All the balls were finished up to the dimensional accuracy of Grade 10 defined in KS B 2001 (Steel Balls fer Ball Bearings) with a size of 9.525 mm. RFL tests were then conducted under the initial theoretical maximum contact stress 6.38 GPa and the spindle speed 10,000 rpm. Gear oil was provided by oiled race as lubricant. The results of RFL test indicated the prerequisitic conditions for the long rolling life of Si$_3$N$_4$ball : (1) the high density, (2) microstructures consisted of small uniformly distributed grains, (3) little glassy phase in grainboundary, and (4) little crystalline phase and secondary phase that induces residual thermal stress due to the differences of thermal expansion coefficient with Si$_3$N$_4$phase.