Asymmetric Shape Control Theory and Practice in Cold Strip Mills

Abstract

In cold rolling process, asymmetric shape defects are still a common problem to strip quality. For the mills with inverse symmetry roll shifting system, different roll wear and thermal contour of top roll system and bottom roll system could cause asymmetric shape defects during shifting operation. In this paper, three dimension finite element simulation models of inverse shifting roll system were established to calculate the parameters and to analyze the effects. Based on the idea in the mill engineering that mill style option depended on the product grade, shifting weakness was evaluated and the opinion of limit shifting was suggested. To improve control effect to asymmetric shape defects in cold rolling, shape control system with asymmetric shape control ability is developed, including asymmetric edge drop control at upstream stands and asymmetric flatness control at last stand. The further improvement of asymmetric shape control theory and practice is the key way to reach the higher precision of shape quality in cold strip mills.