Comprehensive contour prediction model of work roll used in online strip shape control model during hot rolling

Abstract

Initial, thermal and wear contours of the work roll are three major sources of mill disturbance and play critical roles in crown and shape control of strip. To simplify the complex contour curve of the work roll resulting from superposition of three kinds of contour mentioned above in the online strip shape control model, a comprehensive contour concept of the work roll and its predictive calculation model are put forward in the present work. Predictive calculation of the comprehensive contour of the work roll in the online strip shape control model during hot rolling consists of two important parts, namely wear contour calculation and thermal contour calculation, which have a direct influence on the accuracy of shape control. A statistical wear model and a finite difference thermal contour model of the work roll are described in the present work. The comprehensive contour is the sum of grinding, wear and thermal contours. This comprehensive contour calculation model has been applied successfully in a real online strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurement and theoretical analysis. The hit rates (per cent of shape index satisfying requirement) of crown and head flatness of the strips rolled by using the shape control model, which includes the comprehensive contour calculation model, have increased about 16 and 10% respectively, compared with that of strips rolled using manual operation.