Research On Shape Control Theory And Models For Hot Strip Finishing Mills

The present paper was based on the project of profile and flatness control for 950mm hot roll plant of RuiFeng.Based on the theory of rolls' elastic deforming,in view of the four high plate mill,the strip profile influence ratio calculation software was developed with the influence function method.And on the base of the regression analysis of various influencing factors,the high accuracy mathematic models of strip profile influence ratio were built,then a general analytic tool was offered for the building of high accuracy strip shape control model and the optimization of the coefficients.The theory,mathematical model and control strategy of the strip shape control system were researched systematically in the paper.The results of the research work were described as follows:(1)The roll elastic deformation theory of the strip shape control was studied.A calculation method of the roll elastic deformation was derived,with using influence function.The influence functions of the work roll flattening and the flattening between rolls were improved,and convergence exponent and smoothness index of iterative algorithm were put forward.Then the available analytical software on four high rolling mill rolls elastic deformation was developed by Fortran language.(2)Depending on the rolling mill equipment and process parameters,influence factors such as reduction,work roll diameter,back-up roll diameter,special rolling force,roll bending force,work roll crown and load distribution were analyzed systematically,describing influencing ratio variation of influence factors as the change of strip width,and to modify its basic value.With determining the model parameters,the high accuracy mathematic models of strip profile influence ratio and uniform load roll gap crown were built.(3)On the basis of uniform load roll gap crown,the profile and flatness control model was developed by considering the material transverse flow and secondary deformation between mills.The strip critical buckling limit mathematical model was deduced by considering the effect of the potential shape defect and the tension.(4)Compared with traditional strip shape control strategy,this paper putted forward a new type of profile and flatness control strategy.This strategy enhance the quality of the target strip crown with guaranteeing strip flatness quality and bring the shape control capability into full play.At the same time,the calculation models of setting value of each strip shape control were established.The profile and flatness control model and control strategy which were established in this paper have been applied in Tangshan RuiFeng 950mm hot strip rolling finishing mill group,and field application has obtained good results.