The Calculation of Roll Force and Torque in Hot Rolling Mills

Abstract

Equations are derived for the normal roll pressure, specific roll load and torque in hot rolling mills, using the condition for plastic deformation in rolling derived by Orowan, together with von Kármán's equation of equilibrium. Although applying strictly to the rolling of ideal plastic-rigid materials, these equations may be applied to the rolling of materials which strain-harden by using a mean value of the yield stress in the pass. The equations have been checked against measurements made when rolling pure lead at room temperatures, and against the results of the experiments on steel at elevated temperatures carried out at Holfors. There is close agreement between the calculated and measured roll loads, but the roll torque is over-estimated slightly by the theory, above reductions of about 30 per cent in thickness.