Determination of formability considering wrinkling defect in first-pass conventional spinning with linear roller path

Abstract

Flange wrinkling is one of the common defects that occur in conventional spinning process, severely restricting the improvement of forming quality and formability. How to universally determine the formability dependent on flange wrinkling is a critical issue in conventional spinning process. For this end, such a determining method for the formability in the process is proposed to rationally design the forming parameters to prevent flange wrinkling. The method is as follows: firstly, the maximum circumferential stress during the process is calculated at the outer edge of the flange, where the circumferential stress is considered as the combining result of the shrinkage of flange diameter and the bending of flange; then, the formability is determined by comparing the maximum circumferential stress to critical circumferential stress for wrinkling defect. Based on the method, a formability analytical model considering wrinkling defect in the first-pass conventional spinning process with a linear roller path is established. The formability model is validated by experiments and FE simulations at different spinning conditions. Sequentially, the influences of forming parameters and their interaction on the formability considering wrinkling defect are systematically analyzed. Furthermore, the forming diagrams considering wrinkling defect for the first-pass conventional spinning are established. It is found that the feed ratio has the most significant effect on the formability, followed by the blank thickness, the hardening exponent, the feed ratio-hardening exponent interaction and the feed ratio-sheet blank thickness interaction. The smaller feed ratio and hardening exponent, thicker sheet blank and greater relative sheet blank radius are helpful to increase the formability. The research results could provide a theoretical basis and guidance for the selection of forming parameters in the actual production of the first-pass conventional spinning.