Rolled-flatness deviation evolution mechanism induced by transverse inhomogeneous deformation resistance during tandem cold rolling

Abstract

Frequent occurrences of flatness defects during cold rolling have emerged as a significant bottleneck limiting the production of wide-thin high-strength strip. Conventional flatness simulation methods, typically based on idealized and homogeneous material models, fail to capture defects caused by distribution in transverse mechanical properties inherent to the strip itself. In this study, an analytical approach of strip shape, which addresses the limitations of existing models by incorporating actual transverse mechanical property distributions, is pioneered. Compared with conventional methods, the proposed finite element model demonstrates improved accuracy and stability, as validated by industrial production data. The relative error between the calculated and measured rolling force is maintained within 7 %, and the absolute error of the center thickness of the rolled strip is less than 5 μm. It is observed that there is a strong correlation between flatness defects and the initial transverse property distribution, which significantly increases the complexity of flatness deviations control. Furthermore, the influence of transverse property distribution on the evolution of the elastic deflection, inter-roll pressure and 3D pressure distribution is comprehensively analyzed, and the control efficiency of strip shape under relevant conditions is also evaluated.