Improvement in shape control performance of finishing mills in endless rolling production line

Donghua steel continuous casting-rolling(DSCCR)production line is an endless rolling production line independently integrated and developed by a Chinese enterprise.To solve the problem of out-of-control shape caused by insufficient adjustment ability of work roll bending force of DSCCR finishing mills,the backup roll contours of the finishing mill were optimized considering multi-objectives,and varying contact length backup roll(VCR)contours matching the concave work rolls were designed based on the rapid rolls-strip deformation calculation model,which integrated the elastic deformation of the rolls and the fast plastic deformation of the rolled strip.The simulation results showed that VCR configuration can significantly enhance the control efficiency of the work roll bending force and increase the transverse stiffness of rolling mill compared with the conventional roll configuration.In addition,VCR backup roll can improve the contact state between backup roll and work roll.The industrial production showed that the bending force setup value was more reasonable and the strip crown control accuracy was improved.

Generation mechanism of quarter buckle in hot-rolled temper rolling

To reveal the generation mechanism of the quarter buckle in the process of hot-rolled temper rolling,the elastic–plastic finite element method is used to calculate the deformation of the roll and the strip during the temper rolling.The change of the cross section of the strip and the distribution of the longitudinal stress are analysed under different bending forces to obtain the boundary conditions of the quarter buckle.The generation of the quarter buckle is further analysed from the bending and contact flattening of the roll system and the elastic recovery of the strip after rolling.We found that the quarter buckle is closely related to the high-order distribution of the contact flattening between the work roll and the strip and is less affected by the bending deformation of the roll and the contact flattening between the rolls.Finally,a new work roll contour of the locally variable crown is proposed to change the distribution of contact flattening between the work roll and the strip.It is verified through theoretical calculations and industrial applications that the new contour can effectively improve the quarter buckle.