Control strategy of multi-stand work roll bending and shifting on the crown for UVC hot rolling mill based on MOGPR approach

In order to improve the crown control ability and high quality to meet the Profile Contour Flatness Control (PCFC) requirements of wide electrical steel in the hot strip mills (HSMs), the control strategy of multi-stand work roll bending forces and shifting stroke on the crown for the universal variable crown (UVC) mill is established based on the Multi-output Gaussian Process Regression (MOGPR) method. The UVC technology with wide crown control ability is proposed for the upstream stands, as effective and critical crown control for upstream stands, of the HSMs. The prediction model of UVC work roll shifting was developed by integrating the MOGPR method and the production process data, and it has high prediction accuracy and adaptability compared with BPNN and SVR models by using multiple evaluation indicators. The multi-stand control strategy of the UVC work roll bending forces and shifting stroke is obtained according to the shape mechanism model and the prediction model based on the MOGPR method. Compared with the conventional control strategy, it can make the most of shifting stroke and the work roll bending forces fluctuates less, of which, F1, F2, and F3 are reduced by 21.85 %, 36.15 %, and 19.67 %, respectively. The industrial application of the control strategy during rolling achieves remarkable results that the measured high precision crown hit rate of electrical steel is significantly improved in the 1450 mm HSMs.