Camber Regulation in Rough Rolling Process Using Wedge Estimation of Incoming Bar

Abstract

Camber is one of the main problems generated during rough rolling process. However, control of camber is hard problem because few studies have been focused on the problem. The mathematical model for curvature of the centerline of the strip at the delivery side is extremely important because it is helpful to design a controller to reduce camber generation and to predict longitudinal shape of the strip after rolling. However, the former model which was obtained from the studies about side-slipping is not appropriate because the model is based on incorrect assumptions. In this research, a new control algorithm to reduce camber based on estimated entry-side wedge of the bar during rough rolling process is proposed. The process that derives the former model is reviewed in terms of the basic principles of geometry of curve. Also internal inconsistencies of the former model are investigated. A new model for curvature of the centerline at the delivery side is proposed based on the assumption that curved strip is generated only by the elongation difference of the strip. The entry-side wedge was estimated based on the model with the aids of the tangent vector variation and curvature, which can both be obtained using the measured bar centerline. The differential roll gap between DS (drive-side) and WS (work-side) was then adjusted to minimize the delivery-side curvature of the bar using this estimated entry-side wedge information. A three-dimensional simulator that describes a rough rolling process was constructed using FEM (Finite Element Method). The accuracy of the proposed delivery-side curvature model was compared to the old model and the effectiveness of the proposed control algorithm was validated using FEM simulation combined with the proposed camber reducing algorithm.