Warp Phenomenon Analysis in Hemming Process of Autobody Panel

In this paper, the hemming process, which widely used in automobile industry, was studied by a method of constructing mechanical models combined with FEM simulation results. The warp producing mechanism in the straight edge- plane hemming process was analyzed in detail using this mechanical model. The reason why the warp produced at the position of near the contact point between the out panel and the position surface of hemming die during the pre-hemming process, and the phenomena of warp reducing firstly and then increasing before the position point T and the warp reducing again after point T during the final hemming process were interpreted. The work finished in this paper provides a theoretical basis to understand hemming process and a tool to analyze the reasons why warp produced in the hemming processes.