Relations between Roll-force,Torque,and the Applied Tensions in Strip-rolling *

Abstract

Expressions are derived for the roll-force P, and torque G, in strip-rolling under tension, as functions of the pressure distribution on the rolls and of the radius of the deformed arc of contact. By consideration of various artificial distributions of pressure the ratio G/P is shown to depend only slightly on the precise shape of the friction hill, and a linear relation is deduced between G/P and T/P, where T is the difference of the front and back tensions. This is confirmed by experiments on annealed mild-steel strip and it is found also that T/P is approximately equal to the angular arc-of-contact when the torque is zero (Steckel rolling).

A more detailed investigation of the effects of tension, based on the simplest possible hypothesis, indicates that a back tension, T_b, increases the torque per roll by , while a front tension, T _f , decreases it by , where r is the fractional reduction in strip thickness and R is the undeformed roll-radius. The theory indicates also that the roll-force decreases linearly with both front and back tensions. Experimental data confirm the theoretical predictions of linearity, and show that the formula for the effect on torque is accurate over a wide range of tensions.