Study And Application Of AGC Technology In The Thickness Control For Thick Plate

This thesis summarized the development actuality and present application inAGC (Automatic gauge control) technology for thickness plate mills. Based on thestudy of operation of automatic gauge control system on a newly built4300mm wideplates four-high reversing mill in a domestic steel plant. In order to improve thethickness control accuracy for the thickness control, this thesis put forward thereasonable optimization strategy for the AGC system, and the optimization strategyimplemented with good results. For the optimization of AGC system, the main workand results are as follows:(1) By analyzing the basic theories of the mill elastic deformation, springequation, the plate plastic deformation, plastic equation and PH diagram. Targeteddetailing the mainly using pressure AGC in the rolling process of thickness plates,and control theory and model formula of AGC are given. Pressure AGC such asBISRA-AGC, GM-AGC, Absolute-AGC, Dynamic Set AGC are analyzed andcompared, then introduced the using strategy of the feedback AGC, feed-forwardAGC and monitoring AGC in rolling process. So it provides the theoretical basis forthe application of the pressure AGC, and easy to chooses a comfortable model forAGC in the working.(2) For the Hydraulic gap control system, excellent performance is directlyrelated to the calculate accuracy of the AGC system, and it is the basis of the AGC.This thesis introduced as well the hardware and software platform of the hydraulicgap control system, the features of equipment, the mode of automatic control loop,the ramp of gap controller setting, the applications of gap control loop and the thickness compensations. Particularly, the automatic calibration function of thefour-high mill are described in detailed. Through the calibration, it provides a exactmill elastic curve for the thickness calculation mode of the AGC system.(3) The thesis analyzes the impact elements of the plate rolling exit thickness andthe application problems of pressure AGC. Then, the program framework, thecompositions of the load gap and other considerations of AGC system are describedin detail, and introduces the operating mechanism of AGC system control mode.Through analysis, for AGC system, it proposes the factors of thickness calculationincompletely, it needs a depth analysis of force distribution in rolling process.(4) Based on the digestion and absorption of the domestic and foreign advancedtechnology. This paper completed the detailed design, optimization andimplementation of the AGC automatic gauge control system optimization scheme ofheavy plate mill, main technical innovation points, as follows: mill stiffness variableregression techniques; fast AGC technology; rolling force compensation technique;automatic leveling control system. The technology innovation using in this paper，through producing practice, functions have reached the design request. It improvedthe production rhythm, at the same time, it greatly improved the product quality, yieldand performance, and improved the market competitiveness of the product. Theoverall product quantity of all production line increased5%, yield rate increased3%,fault time reduced by15%, created enormous economic and social benefits. Theaverage thickness qualified rate of width plates increased9.64%, and the same platesthickness qualified rate increased8.33%. The key technologies of thickness controlhad good popularization and application value.The optimization schemes which was presented for the AGC systemoptimization in this paper, mainly work from two aspects which was the improvementof AGC control precision and auxiliary functional capacity, and through the analysisfor the production performance, it showed that the new technology has beensuccessfully applied, effectively improved the production efficiency and quality.Through comprehensive analysis, in practical applications it needed to continuallyresearch and improve the existing AGC system.