Increasing the dimensional accuracy of U-bend product of high strength steel sheets by controlling the pressure pad

Abstract

To reduce springback in U-shape of high strength steel sheet, the present paperproposes a new process parameter in U-bending technique. This paper aims to present the effect of clearance between die and counterpunch on springback behavior. The process in this work consists of four steps; (1) clamping of a sheet between a punch and a pressure pad, (2) bending with constant clamping force, (3) pushing-up at bottom of the part by using the pressure pad , and (4) final release tool. From the experimental results, decreasing of bending moment by bottom pushing-up resulted in the springback reduction. An appropriate of the clearance between die and pressure pad combined with bottom pushing-up force can be reduced springback. Our results suggested that the Y-U model, an advanced kinematic hardening, is essential for accurate numerical simulation of springback behavior.