Research On Mill Modulus Measure And Variable Stiffness Thickness Control

Automatic gauge control(AGC)is one of the most important technologies in the field of rolling automation.It is directly related to the quality and economic benefits of strip steel,so it is very necessary to study the automatic thickness control in depth.In this thesis,the thickness control system of the 2250mm hot strip mill of a steel mill is used as the background,and the thickness control system is deeply studied.The difference between the absolute mode and the locking mode of gaugemeter AGC(GM-AGC)is studied.The source values of the thickness reference are different;the calculation of the bounce amount is different.GM-AGC modifies the roll gap compensation value by introducing the thickness gauge gain coefficient to achieve the variable mill stiffness,also called variable stiffness control.The GM-AGC of absolute way is studied,including the mathematical model of thickness calculation and the principle and algorithm of various roll gap compensation functions.The working principle and system of integral monitoring AGC and Smith monitoring AGC are analyzed in detail with the block diagram.The physical meaning of the parameters used in.The essential part of the GM-AGC thickness calculation model,the rigidity of the rolling mill,is discussed in depth.The calibration process of the rolling mill modulus is studied,including the fitting of the leveling,pressing and pressing data,as well as the width and stiffness of the rolling stock.The influence of the width of the rolling stock on the stiffness of the rolling mill is obtained by theoretical calculation.Since the AGC function is turned off by the pressing process,it only depends on the position control system.In order to make the pressing data more accurate and the stiffness calibration more accurate,the fuzzy self-tuning PID control method is used to optimize the hydraulic pressing system,and Simulink is used in MATLAB to simulate and analyze the pressing system,verifying that it is under disturbance and Overshoot and response time for hydraulic cylinder parameter perturbation.The control effect of GM-AGC variable stiffness is studied in depth.Combined with the system block diagram,the expression of the thickness deviation of the thickness of the thickness gauge variable stiffness control system is derived analytically,and the stability,dynamic characteristics and steady state characteristics of the system are studied.The stability and dynamics of the system are independent of the value of the variable stiffness factor and are only related to the inner ring of the hydraulic position.Only the steady-state characteristic is closely related to the variable stiffess coefficient:when working in the absolute mode,the variable stiffness coeficient is 1,which can completely eliminate the disturbance caused by the inlet thickness deviation,but the disturbance of the rolling mill(roll eccentricity,rolling force)does not have any elimination effect,which is the malfunction of GM-AGC principle;when working in relative mode,as the variable stiffness coefficient decreases,the ability to eliminate the inlet thickness difference is also reduced,but Due to the weakened control function of the GM-AGC,its ability to eliminate the disturbance of the rolling mill is improved.