• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 제7회 압연 심포지엄
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• pp.19-22
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• 2009

It is essential to predict the deformed roll profile for the prediction of the strip profile in rolling process. The work roll of the Sendzimir mill has a small diameter in comparison to a barrel length, so that it is well deformed by the rolling pressure. Also it has a complex roll system, so it is difficult to analyze the roll deflection. In this paper, 3D finite element method is used for the analysis of the roll deflection of the Sendzimir due to the contact between rolls. But it takes much time to get the results, so that the on-line model to evaluate the radial deformation of a roll is developed on the basis of the finite element method.

• 한국정밀공학회지
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• 제31권8호
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• pp.653-658
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• 2014

Roll-to-Roll printing process has become a great issue as a breakthrough for low cost and mass production of electronic devices such as organic thin film transistor, and etc. To print the electronic devices, multi-layer printing is essential, and high precision register control is required for this process. Unlike stop-and-repeat printing process, it is impossible to control the register in a static state since the roll-to-roll process is a continuous system. Therefore, the behavior of web such as polyethylene terephthalate (PET) and polyimide (PI) by the tensile and thermal stress generated in the roll-to-roll process as well as motor control of driven rolls has to be considered for a high precision register control. In this study, the correlation between curing temperature and thermal deformation of PET web is analyzed. Finally, it is verified experimentally that the temperature disturbance generates the more serious register error under the higher curing temperature.

• 소성∙가공
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• 제25권3호
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• pp.169-175
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• 2016

The hearth roll, which transfers the cold-rolled strip sheet in a Continuous Annealing Line (CAL), is always subjected to changes in the surface temperature and subsequently experiences thermal stress in service. These variations lead to the generation of thermal cracks on the hearth roll surface as well local plastic deformation. We performed finite element analysis to predict the thermal stress changes on the hearth roll surface and designed the collar shape of the hearth roll to minimize these thermal stresses. Results show that the hearth roll with a collar having an obtuse angle is much more effective than a hearth roll with collar having a right angle when the tangential stress, which is one of main causes leading to surface cracks, is compared for the various conditions. It was found that the tangential stress and the temperature on the surface of hearth roll can be reduced by 51.9% and 26℃ if the shape of roll on collar is re-designed.

• 대한기계학회논문집
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• 제16권4호
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• pp.819-827
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• 1992

본 연구에서는 전술한 바와 같은 반복되는 압연부하에 의한 롤의 피로특성을 규명하기 위해 열연공장의 조압연기중 표본작업 롤의 피로특성을 규명하기 위해 열연 공장의 조압연기중 표본 작업 롤을 선정하고 일정기간의 사용이력을 조사하였으며, 이 를 토대로 롤내부 온도 및 열응력 계산을 수행하여 압연중 발생되는 피로 균열의 크기 를 정량화 시켜보았다. 또 표면 균열관찰 실험 및 롤 표면흠 대응 실험을 통해 피로 균열이 압연판의 표면품질에 어떠한 영향을 미치는지 조사해보았다.

• 대한기계학회논문집A
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• 제35권9호
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• pp.977-982
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• 2011

보강롤 구동 4 단 냉간압연기에서 작업롤과 보강롤 사이의 접촉력으로 인해 발생된 작업롤의 수평력을 고찰하였다. 본 수평력은 작업롤을 수평방향으로 휘게하고 롤갭 형상을 그 만큼 변화시킨다. 본 논문에서는 압연을 정상상태라고 가정하여 작업롤의 수평력을 예측할 수 있는 수식모델을 제시하였다. 해석에 사용된 소재는 고-실리콘(약 3%) 강판이었다. 수평력의 비-정상거동을 고찰하기 위해서 삼차원 유한요소모델을 채용하였다. 두 가지 모델을 이용하여 작업롤의 수평력은 보강롤의 중심으로부터 작업롤의 중심이 벗어난 길이에 따라 변한다는 결과를 얻었다. 그리고 작업롤의 수평력을 최소화 시킬 수 있는 작업롤의 최적 중심이탈 길이를 도출하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.310-313
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• 2007

In roll forming process, a sheet metal is continuously progressively formed into a product with required cross-section and longitudinal shape, such as a circular tube with required diameter, wall-thickness and straightness, by passing through a series of forming rolls in arranged in tandem. In this process, each pair of forming rolls installed in a forming machine play a particular role in making up the required cross-section and longitudinal shape of the product. In recent years, that process is often applied to the bumper rail in the automotive industries. In this study, a optimal roll flower model and proper roll-pass sequence can be suggested by analyzing courcenter strain and longitudinal strain according to the roll-pass with FEM simulation. And also effects of the process parameters on the final shape formed by roll forming defects a evaluated.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2466-2473
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• 2002

In twin roll strip casting process, the design of casting roll is the most important equipment for producing strip. Analyses of heat transfer and deformation for the casting roll are carried out by using the finite element program, ANSYS. Both the elastic deformation and the elasto-plastic deformation under a thermal load are considered in the analysis. Optimization to minimize the volume of roll is performed under the various thermal loads such as the heat flux and the roll speed. Design variables are defined by diameters and positions of the cooling hole in the roll , Although the thermal load remarkably varies, the design variables and objective function are found to be consistent.

• 한국기계가공학회지
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• 제6권4호
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• pp.76-80
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• 2007

Two roll straightener showed the remarkable improvement in straightness betterment of the bar compared with other types of straightener. So, in this study we designed a two-cross straightener curvature for the straightness improvement of a bar and contact sections with respect to the variation of the gap between two-cross roll using nonlinear contact analysis. The Displacement in terms of a intersection angle between roll and bar was predicted on with the effect of a straightness and plastic deformation behaviors of the bar according to the roll drive of a two cross-roll straightener.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.273-279
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• 1999

In this paper the stress and strain behaivor in near homogeneous isotropic matrix of metal like steel was studied roll forming of thin steel sheet for cylindrical pipe. Analytical results reveals a body which is on the area of square thickness along and perpendicular to the width of thin steel sheet is in the state of plane strain during roll forming. As a result construction of analytical method for calculating deformation load and stably deformed length along the width of strained steel sheet was established. Also loads applied during roll forming were analyzed using two typical thin steel sheet 12.3m thick steel sheet with 42.5kg /mm2 yield strength of pipe and 5.3mm thick steel sheet with 32.5kg/mm2 yield strength of pipe. Through this analysis applicability of the analytical method for deformation load during roll forming of cylindrical thin steel pipe was evaluated with a study of necessary production technology for roll forming and design technology for roll forming machine.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.180-187
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• 1999

This document illustrates the relationship between the wire rod wrinkle defect and the roll caliber design. The wrinkle defect is caused by the incongruent rolling conditions of the roll caliber design, the roll adjustment, and the extracting temperature. In this document, we restrict the study scope to the roll caliber design's effect on wrinkle defect at the base of real condition of the No.2 Wire Rod mill, POSCO. There has been wrinkle defect problem in the No.2 Wire Rod Mill, POSCO for many years. The engineers of the wire rod mill have been making efforts to solve the problem. As one of the efforts, we take the samples of the wire rod in the each stands of the 2'nd wire rod mill and then analyze the samples. Through the analysis, we find out the problem of the roll caliber design. So, we suggest the roll caliber design method to be more effective to weaken the wrinkle defect.