Research And Application On Strip Shape Control Model For Hot Rolling

The strip size performance of hot rolling includes width, thickness, profile and flatness.Control technology for width and thickness is relatively mature. With the widely using of AWC(Automatic Width Control) and AGC(Automatic Gauge Control) technology,width and thickness are controlled well. But the profile and flatness problems are outstanding during production in plant site, due to relatively complex and many influence factors, especially for rolling thinner and wider products. So research and developing of shape control system has become a hot and frontier subject in rolling technology field.In this paper, the present situation of shape control model technology is introduced from the point of view of process control model. Shape control model for hot rolling is studied. Then it is applied in practical production. Some functional modules are developed about shape model. And some shape mathematical models are optimized. The main works in this paper are shown as follows:(1) Algorithms of the set-up model and data flow of set-up and self-learning model of shape control for hot rolling are deeply studied. Data structures of shape model are sorted out. Inner and outer data interfaces are finished. Natural exit thickness profile is introduced in the set-up model of shape control. The online calculation time of shape model is saved. It leads to profile distribution more reasonable at the same time to achieve and maintain the target exit flatness as well as the inter-stand flatness.(2) The shape self-learning model is intensively studied. The model algorithm of thickness profile target optimization is developed. It is utilized to modify the target crown automatically when undesirable profile forms are being produced by the mill which can be improved by a modification to the amplitude of the target. The model algorithm of longitudinal thickness profile trend optimization is developed. By measuring the thickness profile at the coils head end and tail end and comparing these results with the thickness profile at the central section, it is possible to identify any error trends and to adjust the dynamic compensation to minimize profile and flatness errors throughout the coil.(3) In accordance with the principle of roll wear, main influence factors of roll wear are analyzed. The online calculation model of work roll wear in finishing mill for hot rolling is established. Causes and influence factors of ‘Cat Ear’ are analyzed. Some technical measurements to avoid ‘Cat Ear’ are discussed. The method and effect of periodic side shift is introduced. It is manifested that the roll wear model developed has a higher accuracy by comparing the measured value and calculated value of roll wear.(4) According to the basic principle of heat transfer theory and the rolling conditions of work rolls in finishing mill for hot strip rolling, the temperature fields of work rolls considering axial and radial heat transfer and two dimensional difference model of heat expansion are established by using the method of finite difference. The calculation results of the model in a China 1580 mm hot mill rolling production line are analyzed.(5) The equipment layout and production process of a China 1580 mm hot rolling are introduced. The data interfaces and trigger timing of set-up model calculation and model self-learning are discussed. The practical application results are presented. The statistic and analysis of production data are performed. It indicates profile and flatness performance achieve a satisfaction control effect.