Experimental study on the cross-shear roll bending process

Abstract

Warping is conventionally regarded as a drawback of asymmetrical sheet rolling caused by speed mismatch-induced cross-shear straining. But, in this paper, by utilizing the warping effect, we developed a novel roll bending process, named cross-shear roll bending (CSRB), for the manufacturing of tubular sections. In the process, the metal sheet is rolled and bended under cross-shear straining by mismatched circumferential speeds of two rollers. The process is capable of manufacturing continuously changeable curvature tubular sections with minimized springback and straight ends and also with increased strength through strain hardening. Experiments show that the CSRB process is effective in forming the tubular sections by the following aspects. (1) The curvature radius decreases as the circumferential speed differential rate increases, but it loses its sensitivity to a relatively larger circumferential speed differential rate. (2) The curvature radius evolves along with the change of thickness reduction rate of the sheet in a V-shape manner, which indicates the existence of a minimum curvature radius. (3) The change of radius ratio poses little effect on the curvature radius. Therefore, by exclusively regulating the circumferential speed differential rate and the thickness reduction rate, the curvature of the sections can be controlled.