Looper-gauge Integrated Control in Hot Strip Finishing Mill Using Inverse Linear Quadratic Theory

Abstract

Hot strip rolling is a significant process in the fields of manufacturing and processing. In order to further improve the control accuracy of looper angle, strip tension and gauge in hot strip finishing mill, an innovative looper-gauge integrated control scheme is developed in this paper. Based on the inverse linear quadratic (ILQ) theory, a proposed control scheme is designed for the looper-gauge integrated system. First, considering the numerous interactions between looper angle, strip tension and gauge, and the disturbances from several sources, a dynamic 6th order state space model is established and validated. Then, the control scheme based on ILQ theory is imported into gauge-looper integrated system. The desired poles are placed according to the dynamic characteristics requirements. The state feedback optimal control law is determined by an improved ILQ design method. Then the multivariable looper-gauge integrated control system is constructed. The proposed control scheme has the explicit ability to achieve desired looper and gauge control performances, with less external disturbances and no sensitivity of strip dimension changing. The effectiveness of the proposed looper-gauge integrated control scheme compared with traditional control strategies is shown in the simulation results. The interactions between looper control and guage control are also minimized.

Coupled Vibration Behavior of Hot Rolling Mill Rolls under Multinonlinear Effects

“…Most studies on rolling mill vibration focus on a single vibration system, such as vertical, horizontal, or torsional vibration. For instance, Sun et al considered the interaction between strip tension and thickness and analyzed the effect of multiple-source external disturbance on rolling mill vibration; they established a vertical vibration model of the rolling mill and further improved the control accuracy of tension and thickness of the hot rolling mill through optimization design [4]. Fan et al analyzed and calculated the structural stability of hot rolling mill rolls and revealed that the gap between the framework and rolling mill rolls can cause the phenomenon of "vibration jump," which destroys the balance of a rolling mill system [5].…”