Leverage asymmetric strip tensions for enhanced control of surface roughness in skin-pass rolling

In skin-pass rolling, ensuring uniform and precise strip surface roughness is essential, as the resulting strip roughness significantly influences tribological condition and paintability of semi-finished products. Therefore, to achieve the desired strip roughness in skin-pass rolling, this study proposes a control strategy for surface roughness using asymmetric strip tensions. For this purpose, a multiscale finite element model is employed to predict the strip roughness under variable thickness reductions, asymmetric tensions, initial strip roughness, and rolling speed. The results demonstrate that thickness reduction is the dominant factor influencing rolling force and surface roughness. Different combinations of asymmetric strip tensions adjust the strip roughness by up to 0.23 µm at 7% thickness reduction and 0.15 µm at 3% thickness reduction. The roughness adjustable range is obtained when the maximum achievable backward and forward tensions are 0.6 kN and 1.2 kN, respectively, for a 1.02 mm thick, and 8.06 mm wide strip. This highlights the potential to control strip roughness using asymmetric tensions. However, peak count of the strip surface remains unaffected by asymmetric tensions, and cannot be controlled in skin-pass rolling. Additionally, the effect of rolling speed is negligible when it exceeds 25 m min −1 at 3% thickness reduction. Furthermore, higher initial roughness contributes to a slight reduction in final strip roughness at 3% thickness reduction but has no impact at 7% thickness reduction. Validation results confirm the strong predictive capability of meso-model for roughness transfer behavior at variable thickness reductions and asymmetric tensions.