An analytical approach to asymmetrical hot-sheet rolling considering the effects of the shear stress and internal moment at the roll gap

Abstract

The stress field at the roll gap was derived in this study so as to take into account the effects of the shear stress and internal moment in the asymmetrical hot-rolling processes. An analytical model was developed with consideration of the pressure-difference distribution between the two driven rolls to investigate the behaviors of sheets or strips during asymmetrical hot-rolling via the slab method. The neutral points between the upper and lower rolls and the sheet, the rolling pressure distribution along the contact interface of the roll and the strip, the shear stress and the internal-moment distribution, and rolling forces as well as rolling torques, can be obtained easily using this model. The rolling pressure, the shear stress and the internal-moment distribution, the rolling forces and rolling torques, as affected by various rolling conditions (e.g. the roll speed ratio, the thickness reduction, the ratio of the roll radius to the thickness of the sheet, etc.) were analyzed systematically, the analytical results being compared with experimental measurements. This comparison verified that the proposed model is valid for predicting the pressure distribution, the rolling force, etc., thus this analytical approach can yield useful knowledge in the designing of the pass-schedules of the asymmetrical hot-rolling processes with twin driven rolls.