Optimization of the VCRpro Backup Rolls for 2250 mm Continuously Variable Crown Hot Strip Mills Based on Particle Swarm Optimization Algorithm

In order to solve the long-standing issue of uneven wear on backup rolls and promote the roll gap stiffness in the 2250 mm continuously variable crown hot strip mills, this study presents an optimization method for the design of the varying contact backup roll promotion (VCRpro) backup rolls to eliminate effectively the undesired contact zones between the work and backup rolls. First, the VCRpro contour represented by a cosine function is established based on the particle swarm optimization algorithm. Then, the 3D finite element model is established to investigate the contact pressures between the rolls under different shifting positions, bending forces, strip widths, and rolling forces. The results demonstrate that the regulation efficiency of the bending force has been enhanced. In comparison with the conventional backup rolls, the crown regulation ability of the bending force has an increase of 19.38%. And the roll gap stiffness has a rise of 15.52%. Moreover, the unevenness coefficient has experienced a maximum reduction of 35% and an average reduction of 25.77%. Industrial production results demonstrated that the VCRpro backup rolls significantly reduce the wear of the rolls compared to the conventional backup rolls, with an improvement of 10.54% in roll self-maintaining.