Research On Thickness And Tension Control System Of Tandem Cold Mill

As important parameters in cold rolling process,the thickness and tension is a nonlinear,time varying and multi variable controlled object.In the rolling process,there is a serious coupling phenomenon between the strip thickness and the inter stand tension,which hinders the independent control of each variable and affects the accuracy of the thickness control.In this dissertation,the thickness and tension control system is studied.First,this dissertation briefly introduces the development situation of strip cold rolling technology,research status of thickness and tension control,process equipment and control system of 2280 tandem cold rolling mill.Then it analyzes the cold rolling thickness and tension control,including the basic equations of rolling process,the basic principle and basic forms of automatic gauge control(Automatic gauge control,referred to as AGC)and automatic tension control(Automatic tension control,referred to as ATC).Finally,analyzes the coupling phenomenon between the thickness and tension in the rolling process,pointed out the necessity of decoupling control.Secondly,analyzes the control mechanism of thickness and tension,establish thickness and tension system model taking the roll reference position and the bridle roll driving motor torque as manipulated variables and the strip exit thickness and the strip entry tension as controlled variables.Then studied the conventional diagonal matrix decoupling,invariance decoupling,multivariable adaptive decoupling based on pole assignment.Finally,designed decoupling controller based on invariance decoupling method for the thickness and tension system,the simulation results verified the effectiveness of the decoupling controller.Finally,introduce and analyze the H? control theory.the robust controllers is designed based on H? control method since there exists the uncertainty of the model parameters perturbation and all kinds of interference in the decoupled thickness and tension system.This method are verified by a two-frame thickness and tension system,and the simulation results show the effectiveness of the H? integral controller.