Experimental investigation of forming defects in flat surface–convex edge hemming

In this paper, flanging and convex edge hemming of aluminum killed draw quality steel was investigated. The investigation was focused on the study of the radius flat hem with an inner sheet. The objective of the study was to determine the influences of the contour radius and flange length on wrinkling, hem-out, roll-in (creep or creepage) and roll-out (growing). A set of complete factorial experiments was designed and conducted in order to determine the effects of the selected experimental parameters. Experimentation provided a design map of failure zones for wrinkling and hem-out as well as fundamental knowledge of important factors in convex edge hemming and factor interactions during different process stages. Results of the experiments were summarized for the use of process and die designers. A future experimental study will focus on pure roll and warp without any wrinkling and hem-out.