Feedback Control of the Contour Shape in Heavy-Plate Hot Rolling

Abstract

This paper deals with the mathematical modeling and feedback control of the contour evolution in heavy-plate rolling. During the rolling process, asymmetric rolling conditions in the lateral direction may lead to a deviation between the actual and the desired plate contour. Such asymmetric rolling conditions are often unknown and hence cannot be compensated in advance. Therefore, a feedback control approach to reduce contour errors during the rolling process is presented. However, the measurement of the plate contour is subject to a transport delay, which complicates the design of feedback controllers. The angular velocity of the plate is also linked with its contour evolution. This is why the delay-free measurement of the angular movement is used in a 2-degrees-of-freedom Smith-predictor structure. The basis for the control approach is a mathematical model describing the nexus between the angular velocity and the contour evolution of the plate. The feedback controller utilizes an upstream and a downstream measurement of the contour and the movement of the plate. Furthermore, a proof of the robust stability of the proposed control concept is presented. Simulation results and measurements from an industrial plant demonstrate that the presented approach can significantly reduce the contour errors of rolled plates.