Springback/springforward behaviour of dp steels used in the automotive industry

Abstract

The springback/springforward behaviour in a V-die/punch of DP600 and DP780 steels used in the automotive industry was investigated. For this study, experiments were carried out by using different combinations of parameters, including material thickness, die/punch radius, bending angle and rolling direction and the resulting measurements showed that the DP780 steel consistently exhibited greater springback values than the DP600. Augmentation of the rolling direction at an angle from 0 degrees to 90 degrees and punch radius inhibited springback formation and hastened springforward, particularly for small bending angles. The springback angle decreased with increasing material thickness and curvature radius, and increased with the bending angle, particularly for the punch tip radius of 2 mm. Increasing the ratio of curvature radius to material thickness (rt(-1)) also caused the springback to decline. In addition, a new dimensionless parameter was developed and the critical value for calculating the transition from springback to springforward was determined.