Research On Theory And Strategy Of PVPC During Plate Rolling Process

The bad plan view pattern of products (non-rectangular) has a great influence on the yield loss in plate production. Therefore, studying the deformation law of plan view pattern and using the Plan View Pattern Control (PVPC) strategy in the actual production can reduce cropping and trimming loss and improve the yield of plate significantly.The PVPC theory and strategy of MAS rolling are researched in this paper in the background of WISCO3000mm plate production line automatic control system modification project, the regression models of the cropping and trimming prediction and PVPC are optimized, multiple-point setup method and dynamic gap control in MAS rolling process are studied and realized, good effect of PVPC is obtained. The main researches are as follows:(1) The basic theory of PVPC. The rolling force calculation model and pressure AGC, which is closely related to the thickness accuracy of MAS rolling, are introduced. The change of gripping angle, neutral angle, contact arc length and forward slip in MAS rolling with ordinary rolling process are compared. Metal flow and metal deformation law are studied in MAS rolling process.(2) PVPC size prediction of MAS rolling. Predicted Values of trimming and cropping are calculated by PVPC prediction models in the condition of ordinary rolling on the basic of PVPC theory. The method of nine-point dynamic setup is used and the positions and reducing corrections of set points are determined in presizing MAS and broadsizing MAS rolling process.(3) Determination of MAS rolling control strategy. Precise micro-tracking along length of plate is used to track the position of plate in the mill according to the actual feedback roller speed and forward slip and insure reduction speed matching with rolling speed by target thickness in MAS rolling process. Based on considering the regression models of mill spring, oil film thickness compensation and plate width compensation, the deviation between calculated exit thickness and target thickness is determined. Then roll gap adjustment is calculated through the ABS-AGC in order to control dynamic varying thickness. (4) Programming for PVPC. Programs of some important models in MAS rolling process are compiled by STEP7. The control effect of field application shows that MAS can improve the plan view of products and enhance yield.