• Journal of the Korean Society for Precision Engineering
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• v.9 no.2
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• pp.101-107
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• 1992

디입그로잉용 냉간 압연 강판의 인장시험편에 디지탈 이미지 프로세싱 기술을 적용하여 표면에서의 변형 및 변형도 분포 구하는 방법을 제안한다. 이 방법은 시편표면상의 절점 위치를 이미지 프로세싱에 의해 결정하는 부분과 이들 위치점들을 이용하여 변형도를 계산하는 두 부분으로 구성되어,있다. 본 연 구에서는 시편상의 각 절점 위치를 구하기 위해 검은 원형의 반점들로 배열된 사각 형상의 격자를 사용하 였고, 이미지 프로세싱에 의해 구해진 절점 좌표를 이용하여 소재 표면에서의 변형 패턴, 주 변형도 분포, 유효 변형도 분포, 임계 변형도 등을 구하였다. 인장시험하는 동안 시편 표면상의 국부 네킹이 발생될때 까지 주변형도에 의한 변형 이력은 거의 적선적으로 변형되고 있기 때문에, 유효 변형도 값은 매 변형 단계마다 변형도 증분의 누적에 관계없이 거의 일정한 값을 보여주고 있었으며, 최대 유효 변형도는 시편의 중앙부에서 나타나고 있음을 알 수 있었다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.184-187
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• 2003

The simulation program is developed to get the target strip crown of high strength steel in the continuous hot strip rolling. The developed program consists of several sub-program, which contains work roll shifting pattern, roll wear profile, roll thermal expanded profile and strip profile. Also, the variation of strip profile is investigated according to roll deflection and flattening. The results are compared with the values observed from the actual hot rolling of high strength steel. And effect of bender force on the strip profile is studied. The strip crown is shown to decrease with increasing bender force.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.164-167
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• 2003

Profile ring rolling process is simulated by using the general purpose commercial finite element analysis software MSC.Superform Because the deforming region is restricted to the vicinity of the roll gap, only a ring segment spanning the roll gap is analysed in order to save computation time and cost. A profile ring with an external round groove is chosen as an example to be analysed. The rolls with and without groove were analysed to compare the amount of side spread. It is found that the grooves in the rolls reduce the amount of side spread.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.9
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• pp.869-874
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• 2015

We developed an LSDC (Load Shift and Load Distribution Control) technology in order to improve coil quality and productivity by reducing tension fluctuation especially for the tail of the strip in the down coiler in hot strip mills. To adapt the new controller, the torque and speed distribution between the zero pinch roll, pinch roll, and mandrel are needed. The proposed controller is a combination of an LSC to share the tension between the mill stand and the mandrel, and an LDC to shift the torque load from the zero pinch roll to the pinch roll. From the simulation, the proposed controller is verified under the torque disturbance. Using a field test, the torque deviation decreased by nearly 50% through utilization of the LSDC control.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.963-968
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• 2003

The continuous process systems usually consists of various components: driven rollers. idle rolls, load-cell and so on. Even a simple fault in a single component in the line may cause a catastrophic damage on the final products. Therefore it is absolutely necessary to diagnosis the components of the continuous systems. In this paper, an adaptive eccentricity compensation method is presented. And a new diagnosis method for transverse roll shape defects on rolling process is developed. The new method was induced from analyzing the rolling mechanism by using rolling force model, tension model, Hitchcock's equation, and measured delivery thickness of materials etc. Computer simulation results also show that the proposed diagnosis methods is very effective in the diagnosis of 3-D roll shape

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.78-87
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• 1999

A mathematical model for the stress free surface profile in Over-Round and Round-Oval grove rolling, which can be used effectively in the calculation of pass area, is presented. The new model has generality, simplicity and accuracy for practical usage. The stress free surface profile of an outgoing stock can be modeled when the maximum spread of it known a priori. The equation for the stress free surface profile is formulated from the linear interpolation of the radius of curvature of an incoming stock and that of roll groove to the axis direction. In developing the analytical model, the effect of rolling temperature and friction between roll and work piece(stock) were not considered since the geometry of roll groove and the incoming work piece were assumed a dominant factor which decides the stress free surface profile of the outgoing stock. A simulation with the analytical model developed also has been carried out to demonstrate the stress free surface profile of the outgoing stock.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.98-106
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• 1999

In this study cold rolling process for the irregular cross-sectional shape has been investigated. The product analyzed in present study is the steel cutter, which is frequently used to cut the desired shape on leather. Because steel cutter always has a irregular cross-section, after rolling process the workpiece is severely bended to every direction. The bending of the workpiece affects the processed performed after rolling such as heat treatment and grinding, then that of the workpiece becomes more severe. In this study, therefore, to prevent the bending of the workpiece to the left and right sides. rigid-plastic finite element method has been utilized and in order to find optimal roll geometry rapidly, one dimensional equal interval search technique has been also introduced. By using both rigid plastic finite element method and optimum technique, cold rolling process for the irregular cross-sectional shape has been successfully investigated.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.99-99
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• 2009

마그네슘은 지구상에서 존재하는 금속 중 가장 가벼운 실용화 금속이다. 따라서 최근 산업 전반적으로 대두되는 경량화에 대응하는 데 중요한 소재로 각광받고 있으며 그 활용이 활발하게 추진되고 있다. 본 연구에서는 이러한 동향에 대응하는 일환으로 POSCO에서 생산되고 있는 압연 마그네슘판재를 적용하였다. 적용 대상은 철도 분야의 경량화를 위한 전장품을 선정하고, 실물 크기로 제작하였다. 제작은 두께 3.5 mm 의 판재를 사용하였으며 용접은 Friction Stir Welding 및 GTAW 를 사용하였다. 그림1에 제작이 완료된 형상을 나타낸다. 그리고 제작중의 용접과정에 대하여 3차원 열탄소성 해석을 수행하여 변형 과정에 대한 검토를 수행하였다. 그림2에 해석과정의 한 예를 나타낸다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.110-114
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• 1997

The major object in this report is the curvature prediction of front end downward bending in plate rolling. Because of relations front end shape and curvature in plate, many simulations were carried out to obtain empirical model. Simulation conditions, for example the position and the size of bottom stripper or roller table etc., were limited to the POSCO conditions. Though the result in this report can be applied to the special case, the tendency of this result is similar to the many cases. So the empirical model equation can be improved or expanded to many simulation conditions.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.223-228
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• 2007

The profile ring rolling process of Ti-6Al-4V alloy was investigated by finite element(FE) simulation and experimental analysis. The process design of the profile ring rolling includes geometry design and optimization of process variables. The geometry design such as initial billet and blank sizes, and final rolled ring shape was carried out with the calculation method based on the uniform deformation concept between the wall thickness and ring height. FEM simulation was used to calculate the state variables such as strain, strain rate and temperature and to predict the formation of forming defects during ring rolling process. Finally, the mechanical properties of profiled Ti-6Al-4V alloy ring product were analyzed with the evolution of microstructures during the ring rolling process.