• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.93-95
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• 2007

Studies on ski-end shape control at the top end of rolling plate in heavy thick plate mill by using FEM analysis and measuring system have been performed. Plate shape behaviour at the top-end on rolling by the two different methods in finishing rolling process has been observed. One is to minimize the height of ski-end by using pass line based on the relational model between shape factor and pick-up and the other one is to prevent turn down problem caused by the impact between table roller and down bended plate on rolling by using roll speed difference. To minimize the height of ski-end, the prediction models based on the FEM analysis and measuring data was developed. The control method of ski - end shape on finishing rolling process was applied in actual mill and the height of ski-end was reduced by about 50% compared with conventional operation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.429-437
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• 1999

Width variation of the top and bottom ends of steel at finishing rolling in a plate, has been investigated. It was found that width variation after finishing rolling is affected by edging, broadside rolling ratio, longitudinal rolling ratio, width shape after broadside rolling, temperature, width-to-thickness ratio, and so on. A neural network modelling of back propagation has been conducted on the width variation during rolling. Based on these prediction models, a width control system, by which the roll opening and closing of the hydraulic AWC edger can be adjusted during edge rolling in finishing rolling passes, has been developed. Compared to conventional width model, the neural network model is much accurate in a model. The width control system is applied to a newly built production mill.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.438-446
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• 1999

Crop minimization of the top and bottom ends of hot rolled plate, in a plate, in a plate mill, has been investigated. The existing model to determine the edging pattern at the finishing rolling pass was not reasonable to get high width accuracy and rolling yields. New models including width prediction have been formulated by using neural network model of back propagation learning algorithm and statistical analysis based on the actual production rolling data to give the optimal pattern for minimizing trimming loss. Using these models, at a given rolling condition of broadside pass and finishing pass and the permissible condition of width variation, it was possible to minimize crip at the top and bottom ends according to optimum procedure in plate mill. An application to improve the plan view pattern reduced width variation by 23% and crop length by 30% on average with an effective fishtail crop shape.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.499-504
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• 1993

To find a way for establishing work roll initial crown according to roll conditions, computer simulation for predicting plate crown in plate mill is done and effects of roll conditions on plate crown is analysed. Roll gap profile and plate crown are measured to be compared to the calculated values. As a result,a regression equation to establish work roll initial crown according to roll cooditions such as backup roll diameter, backup roll crown and work roll crown is obtained.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.73-81
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• 1995

To find a way for establishing work roll initial crown according to roll conditions, computer simutation for predicting plate crown in plate mill is done and effects of roll conditions on plate crown is analyzed. Toll gap rorfile and plate crown are measured to be compared to the calculated values. As a result, regression equation to establish work roll initial crown according to roll conditions such as backup roll diameter, backup roll crown and work roll diameter is obtained.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.6
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• pp.634-640
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• 2009

The plate manufacturing processes are composed of the reheating furnace, finishing mill, cooling process and hot leveling. The finishing rolling mill (FM) as a reversing mill has produced the plate steel through multiple pass rolling. The automatic gauge control (AGC) is employed to maintain the thickness tolerance. The high grade products are forming greater parts of the manufacturing and customers are requiring strict thickness margin. For this reason, the advanced AGC method is required instead of the conventional AGC based on the PI control. To overcome the slow response performance of the conventional AGC and the thickness measurement delay, a fuzzy AGC based on the thickness deviation and its trend is proposed in this paper. An embedded controller with the fuzzy AGC has been developed and implemented at the plate mill in POSCO. The fuzzy AGC has dynamically controlled the roll gap in real time with the programmable logic controller (PLC). On line tests have been performed for the general and TMCP products. As the results, the thickness deviation range (maximum - minimum of the inner plate) is averagely from 0.3 to 0.1 mm over the full length. The fuzzy AGC has improved thickness deviation and completely satisfied customer needs.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.13-16
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• 2000

In the hot strip mill, a bad threading and shape of strip strip in the finishing mill was caused by asymmetric rolling In roughing min. Mathematical analysis for camber control of roughing mill in hot strip rolling has been developed. Each equation in the camber control model was derived from geometrical characteristics of camber mechanism. The model can predict variables such as wedge, side slippage and roll force difference etc. from a measured camber value and then find an optimum roll gap condition for minimizing camber in the next pass.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2836-2844
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• 2000

Thickness control of hot-rolled strips has become an important issue in recent years because of the need for improving the quality of the hot-rolled strip. In this study, a modifying method of rolling force set-up with consideration of spread was developed to improve the thickness uniformity at the finishing rolling units in hot rolling. Through the analysis of real production data it was found that the accuracy of the rolling force determined from the finishing mill set-up (FSU) model dominantly governed the thickness uniformity in rolled plates at the front. Based on this analysis , several examples were selected to calculate the spread of rolled plate using three dimensional rigid thermo-viscoplastic finite element program. FE analysis results were used to train the neural network system that can predict the spread hot-rolled plate and the rolling force was modified based on the predicted value of spread. The modified rolling forces were closer to the measured rolling force so it can be expected that the accuracy of thickness uniformity of hot-rolled plate will be improved.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.208-215
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• 1999

To increase rolling yields by minimizing trimming losses of hot-rolled plate, optimization logic for the edger model has been developed. The logic to determine optimum edging amount model has been formulated on the basis of actual production rolling data. In case of broadside rolling, the fish tail shape at the sides of plate was better for reducing the crop loss and this could be achieved when the edging amount of broadside rolling was increased. At a given broadside rolling ratio, methodology to determine optimum edging amount for the finish rolling which could minimize the width deviation of plate were systematically derived. Therefore, for a given broadside rolling condition and the permissible tolerance in width deviation of plate, it was possible to optimize the edging amount in finish rolling to maximize rolling yields. The application of optimization logic in this study increased rolling yields from approximately 10% to 30% at various longitudinal eding raitos.

• Transactions of Materials Processing
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• v.18 no.4
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• pp.290-295
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• 2009

The roll gap set-up in the finishing mill is one of the most important technologies in the hot plate rolling process. As the target thickness can be obtained by the correct set-up of the roll gap, improving the roll gap set-up technology is very critical for plate thickness accuracy. The main cause of thickness variation in hot plate mills is the non-uniform temperature distribution along the length of the slab. The objective of this study is to adjust the roll gap set-up for the thickness accuracy of plate in hot rolling process considering top-end temperature drop. Therefore this study has concentrated on determining the correct amounts of thickness variation according to top-end temperature drop and roll gap to compensate thickness variation. The control method of roll gap set-up which can improve the thickness accuracy was proposed. The off-line simulation of compensated roll gap significantly decreases top-end thickness variation.