Research On Gauge Control Of Reversible Cold Rolling Mill

With the development of economic and social, the proportion of cold-rolled strip steel in total steel consumption continues to increase.The thickness and shape of strip are important quality indicators. Automatic gauge control is one of the key technologies in strip rolling fields. It is directly related to the product quality and economic efficiency. Therefore, theoretical analysis and applied research for thickness control system have important practical significance.This paper is based on a stainless steel cold rolling mill.The object is Sendzimir twenty roll reversing mill.The thesis introduces the basic theory of thickness control, the reason for strip thickness fluctuations, the variation for strip thickness, the thickness control mode of sendzimir mill, and this paper analyses the thickness control model structure of the sendzimir twenty roll reversing mill. On the basis of analysis of inner ring and outer ring of feedback control system, the system model is brought in, and calculates PID values.In order to solve the effect of pure lag caused by Instrumentation, smith predictive controller is applied to AGC control system. When the model accurately matches, smith predictor controller is good at working out the effect of lag link. It is favorable in dynamic performance and steady-state performance. However, because of temperature increment, the changes of strip stiffness and mill devices worn, the model can not exactly match At the same time, dynamic performance of smith predictor controller will decline; overshoot will increases; response time will extend; disturbance rejection performance is not satisfactory. To solve this problem, this paper introduces generalized predictive controller which has the ability of self-tuning control and system identification.It is applied to thickness control system. In the control process, prediction models can track the change of system features by online identification, and reflect the change in controlled object synchronously. It solves the impact of Mill model parametric variation effectively. Identification model is used to adjust the controller parameters. The system can restrain the impact of disturbance, so the system is good at follow performance and robustness.Finally, the paper analyses and simulats the control performance of cold rolling mill thickness predictive control system. The results indicate that the design of generalized predictive control system not only has good performance of anti-disturbance, but also adapts to the changes of the parameters. Control effect is satisfied.