• Title/Summary/Keyword: rolling

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Study of Edge Crack Growth According to Rolling Condition in Cold Rolling (냉간압연공정에서 공정변수에 따른 엣지 크랙 성장에 관한 연구)

  • Cui, X.Z.;Lee, S.H.;Lee, S.J.;Lee, J.B.;Kim, B.M.
    • Transactions of Materials Processing
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    • v.18 no.5
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    • pp.377-384
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    • 2009
  • The shape of edge cracking in rolling process generally occurred "V" shape. This cracking is successively generated at width edge of strip. The edge cracking is developed to center of strip during rolling process. In the results, the strip is occurred fracture, and the productivity is gone down because of the extensive production time. Accordingly, we need to control crack propagation during rolling process. But, the control of cracking is very difficult in rolling process. Previously the studies of edge cracking were mainly performed on hot rolling process. In this paper, the shape of the edge cracking in rolling was estimated according to process conditions such as initial edge crack size, reduction ratio and tension using FE-simulation and the simplicity experiments on cold rolling process.

Large enhancement in mechanical properties of the 5052 Al alloys by cryogenic and warm rolling (극저온 압연 및 온간 압연 기술을 이용한 5052 알루미늄 합금의 기계적 성질의 향상)

  • Gang, E.G.;Lee, S.H.;Lee, J.C.;Nam, W.J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.10a
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    • pp.81-83
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    • 2007
  • Cryogenic rolling combined with warm rolling has been found to be more effective than only cryogenic rolling procedure in improving the strength of a 5052 Al alloy. In this study, cryo-rolled 5052 Al alloys were aged at $175^{\circ}C$. Warm rolling was conducted after dipping plates into silicon oil bath. A notable increase of tensile strength is achieved by the precipitation during warm rolling. The mechanical behavior of this alloy was investigated by hardness and tensile tests. The microstructure was investigated by transmission electron microscopy. It was found that the cryogenic rolling combined with warm rolling was very effective in improving tensile strength.

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Effect of Lubrication during Hot Rolling on the Evolution of Textures at the surface of 18%Cr Ferritic Stainless Steel Sheet (페라이트계 스테인리스 강의 열간압연 시 표면 층의 집합조직 발달에 미치는 윤활의 영향)

  • Pyon, Y.B.;Kang, H.G.;Huh, M.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.411-414
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    • 2008
  • In order to study the effect of lubrication during hot rolling, ferritic stainless steel (FSS) sheet were hot-rolled with and without application of lubrication. The effect of two hot rolling processes on the evolution of texture and microstructure after hot rolling, cold rolling and subsequent recrystallization annealing was studied by means of macro-texture analysis and microstructure observations. After hot rolling, the specimen rolled with lubrication showed rolling textures at the sheet surface, while the specimen rolled without lubrication displayed shear textures in the outer layers of the sheet. Hot rolling with lubrication was beneficial to the formation of strong recrystallization textures at sheet surface. However, hot rolling with lubrication led to the formation of orientation colonies in outer thickness layers of the recrystallized sheet.

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Simulation of H-beam rolling process using FEM (FEM을 이용한 H형강 압연공정 해석)

  • Park, C.S.;Kim, J.M.;Woo, K.M.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.419-422
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    • 2008
  • It is most important to design the roll pass in shape rolling process. However, roll pass design has been accomplished by experience and intuition of a skilled engineer up to now. And it has being produced throughout a lot of trial and error. Thus, in this study, we tried to analysis the rolling process of H-beam by using FEM program for the quantitative evaluation of the plastic deformation. It could be predicted that rolling load, torque, shape of cross section and distribution of effective strain each pass by the analysis of rolling from break down mill(2 Hi rolling) to finishing rolling(Universal rolling) considering the heat transfer.

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Roll Force Prediction of High-Strength Steel Using Foil Rolling Theory in Cold Skin Pass Rolling (고강도강의 냉간 조질 압연 시 호일 압연이론을 이용한 압연하중의 예측)

  • Song, Gil Ho;Jung, Jae Chook
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.2
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    • pp.271-277
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    • 2013
  • 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.

Recent Trends in Flat Hot Rolling of Steel (열간 압연판재 제조기술의 최신동향)

  • 이준정
    • Transactions of Materials Processing
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    • v.11 no.1
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    • pp.24-35
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    • 2002
  • Recent trend and future prospect of flat rolling of steel has been summarized based on the earlier reports. Key technology in the plate rolling is to have ultra fine microstructure having high resistance against crack propagation during application. Heavy accelerated cooling facility and high power rolling mill will be helpful to develope the high toughness steel. Precise modeling of properly prediction based on deformation and transformation imposed on microstructure of steel during processing is highly anticipated. For the hot strip rolling process, new trend is lies on the production of ultra-thin gauged hot strip to substitute cold rolled strip. For the substitution of cold rolled strip into hot rolled strip widely, high formable property of hot strip is highly required. For the formabilit, the ferritic rolling of extra low carbon steel under high lubricated condition is essential. Recently introduced semi-continuous thin slab and rolling mill line is very plausible to develope those kinds of products easily In the view groin facility combination. New idea to modify the existing continuous hot strip mill line to produce the ultra thin-gauged hot strip in an economic way is suggested in this report.

Critical heat flux (CHF) in pool boiling under static and rolling conditions

  • Tanjung, Elvira F.;Albdour, Samah A.;Jeong, Yeon Uk;Jo, Daeseong
    • Nuclear Engineering and Technology
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    • v.52 no.3
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    • pp.520-529
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    • 2020
  • Experimental investigations were attempted to simultaneously observe the vapor behaviors and critical heat flux under static and rolling conditions. From visualization results, vapor initiated, grew, and detached individually in a vertical direction from the static heated surfaces (at 10, 20, and 30°). While under rolling motion, initiated vapor grew, and interacted with each other, resulting in forming a wider dry spot on the heated surface. Also, it was observed that the vapor drifted upward and stayed on the heated surface longer compared to under static condition. The faster the platform rolls, the longer the vapor stay on the heated surface, significantly decreasing the CHF. On the other hand, as the platform rolls slower (at high rolling period), CHF increases. CHF was decreased with increasing maximum rolling amplitude and inclination angle under both conditions (static and rolling). CHF under rolling conditions was noticed to be lower than under static condition except at maximum rolling amplitude of 10°. The bubble departure frequency at a maximum rolling amplitude of 10° was the highest among all of rolling amplitudes, thereby enhancing the CHF. These results indicate that rolling motion significantly affects vapor behaviors and CHF.

BDM Rolling of Middle Sized H-beams from a Bloom (블룸을 이용한 중형 H 형강 BDM 압연 공정 연구)

  • Kim, J.M.;Kim, K.W.;Kim, B.M.
    • Transactions of Materials Processing
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    • v.25 no.1
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    • pp.43-48
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    • 2016
  • H-beams are generally produced by hot rolling composed of a Break Down Mill (BDM) and a Finishing Mill (FM). The goal of the current study was to develop BDM rolling of H300x300 beams from blooms slit from slabs. In order to manufacture H300x300 beams, the caliber design and the pass schedule of BDM rolling were proposed for a bloom instead of a beam blank. The proposed BDM caliber design and pass schedule were tested using FE-simulation and pilot tests. For the major shape dimensions, such as flange width, web height, web thickness, as well as BDM rolling loads, a comparative analysis between the FE-simulation and the pilot rolling tests was conducted. The results of FEM analysis and pilot rolling tests showed good consistency. Moreover, BDM rolling loads were predicted to be in the range of allowable rolling loads. It was concluded that the designed BDM rolling is suitable for implementation within current manufacturing capacity.

A Study on the Prediction for Rolling Force Using Radial Basis Function Network in Hot Rolling Mill (방사형기저함수망을 이용한 열간 사상압연의 압연하중 예측에 관한 연구)

  • 손준식;이덕만;김일수;최승갑
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.10a
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    • pp.368-373
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    • 2003
  • A major concern at present is the simultaneous control of transverse thickness profile and flatness in the finishing stages of hot rolling process. The mathematical modeling of hot rolling process has long been recognized to be a desirable approach to investigate rolling operating practice and the design of mill equipment to improve productivity and quality. However, many factors make the mathematical analysis of the rolling process very complex and time-consuming. In order to overcome these problems and to obtain an accurate rolling force, the predicted model of rolling force using neural networks has widely been employed. In this paper, Radial Basis Function Network(RBFN) is applied to improve the accuracy of rolling force prediction in hot rolling mill. In order to verify and analysis the performance of applied neural network, the comparison with the measured rolling force and the predicted results using two different neural networks - RBFN, MLP, has respectively been carried out. The results obtained using RBFN neural network are much more accurate those obtained the MLP.

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A Study on the Prediction for Rolling Force Using Radial Basis Function Network in Hot Rolling Mill (방사형기저함수망을 이용한 열간 사상압연의 압연하중 예측에 관한 연구)

  • Son Joon-Sik;Lee Duk-Man;Kim Ill-Soo;Choi Seung-Gap
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.6
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    • pp.29-33
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    • 2004
  • A major concern at present is the simultaneous control of transverse thickness profile and flatness in the finishing stages of hot rolling process. The mathematical modeling of hot rolling process has long been recognized to be a desirable approach to investigate rolling operating practice and the design of mill equipment to improve productivity and quality. However, many factors make the mathematical analysis of the rolling process very complex and time-consuming. In order to overcome these problems and to obtain an accurate rolling force, the predicted model of rolling force using neural networks has widely been employed. In this paper, Radial Basis Function Network(RBFN) is applied to improve the accuracy of rolling force prediction in hot rolling mill. In order to verify and analyze the performance of applied neural network the comparison with the measured rolling force and the predicted results using two different neural networks-RBFN, MLP, has respectively been carried out. The results obtained using RBFN neural network are much more accurate those obtained the MLP.