2016 Volume 57 Issue 660 Pages 60-65
High-strength steel sheets are increasingly applied to automotive bodies for weight reduction in order to meet the needs for reduced environmental impact. However, dimensional defects resulting from springback are serious issues, and effective methods of predicting and reducing such defects are required. In this study, we propose and validate the advantage of the stroke-returning deep-drawing process, in which stroke is returned to the specified depth after drawing to the bottom dead point. The following results were obtained. Firstly, by the stroke-returning deep-drawing process, the twist angle became approximately zero. Secondly, the occurrence of bottom curvature made the sidewall curvature increase. Thirdly, when bottom curvature did not occur, sidewall curvature decreased in accordance with the equation of wide direction stress. Finally, the twist angle and sidewall curvature decreased concurrently upon deeply drawing and the greatly returning stroke process.
