Influence of asymmetric strip tension on surface roughness transfer in skin-pass rolling with small roll radius under dry conditions

Abstract Textured work rolls are utilized in skin-pass rolling to achieve the specific surface finish of the strip, affecting the product properties, such as friction coefficient and paintability. Therefore, to achieve effective property control, it is essential to control surface finish while maintaining geometric accuracy. However, both geometric accuracy and surface finish are influenced by the rolling force, necessitating decoupling for independent control. In this work, asymmetric strip tension is considered as an additional actuator, alongside the roll gap actuator, to investigate the potential to control the surface roughness without influencing the thickness reduction, thereby obtaining the desired product properties. For this purpose, a numerical study is conducted using a finite element multi-scale model with different thickness reductions and strip tensions. Results indicate that, compared to the mean roughness of 2.34 μm at the symmetric case with backward and forward tensions of 0.2 kN, the roughness increases by 7.7% with increasing the forward tension to 1.2 kN and decreases by 2.1% with increasing the backward tension to 0.6 kN, at 7% thickness reduction. This variation in roughness is attributed to the effect of strip tension on the relative movement between the work roll and the strip material. Therefore, applying asymmetric strip tension emerges as an effective strategy to ensure both surface finish and geometric accuracy simultaneously in skin-pass rolling.