Optimisation of backup roll shape in hot strip mill based on contact pressure between rolls

Aiming at the abnormal wear of rolls and board shape control problems caused by the uneven distribution of contact pressure between rolls during hot continuous rolling, this paper proposes an optimal design method for the backup roll system based on the advantageous working conditions of the rolling plan. Taking a 2250 mm hot strip mill as the research platform, this study establishes a three-dimensional elastic–plastic finite-element model and systematically quantifies the influence of key process parameters (including rolling force, board width, roll bending force, and roll shifting position) on the contact pressure distribution. On this basis, a two-step roll shape optimisation strategy is proposed, with the advantageous working conditions derived from production data statistics as the optimisation target: first, the chamfering parameters are optimised to suppress the pressure peak at the edges; then, the non-uniformity of the overall pressure distribution is improved by superimposing the inverse continuously variable crown curve in the middle region. The results show that compared with the original roll shape, the optimised roll shape significantly reduces the peak value contact pressures on the operation side and drive side by 32.72% and 34.97%, respectively, while the non-uniformity of pressure distribution is reduced by up to 72.18% under advantageous working conditions. Further comprehensive performance analysis and industrial trial verification revealed that the optimised roll profile demonstrated superior stability and robustness under various specifications and process parameters, with board shape control capability improved by 4.1–24.3%, effectively addressing the issue of bright band wear on the backup roll. This study provides important theoretical basis and engineering application examples for the precise design and service life prediction of high-performance rolls.