Understanding the regulation ability of roll bending on strip shape in a CVC-6 tandem cold mill using a 3D multiple stand FE model

Roll bending is a common technique to regulate the strip shape in tandem cold rolling (TCR), but its regulation ability at each stand is poorly understood at present. In this study, based on a 3D multiple stand elasto-plastic finite element (EPFE) model, the effects of work roll bending (WRB) and intermediate roll bending (IRB) on the strip crown, strip flatness and elastic deformation of work roll (WR) were quantitatively studied at each stand in the TCR. Results show that the regulation abilities of WRB and IRB on the strip crown both show a downward tendency from Stand 1 (S1) to Stand 5 (S5), which both depend on the strip plastic rigidity. Moreover, under various WRBs and IRBs, the strip shape is mainly determined by the elastic deflection of WR in the upstream stand, while it is determined combinedly by the elastic deflection and flattening deformation of WR in the downstream stand. Furthermore, the regulation ability of WRB on the strip crown and quadratic flatness is at least 2.5 times larger than that of IRB. The experimental results show that the developed multiple stand EPFE model can well predict the trend of the quadratic and quartic flatness between coils. These findings help understand the influence mechanism of the roll bending on the strip shape and improve the strip shape by optimising the roll bending in the TCR.