Abstract

Sheet metal forming processes are very common manufacturing and leading processes in automotive and aerospace industries. Flexforming is one of the sheet metal forming processes which is preferable due to its flexible manufacturing capabilities and its ability to produce multiple parts simultaneously. Among flexformed parts, convex contoured shaped ones are very common and wrinkling is a characteristic defect for those kinds of parts. Prediction of wrinkling before manufacturing is highly crucial in order to reduce scrap rates, labor time, and other unexpected costs. In this research work, extensive experiments were conducted with convex contoured parts on a flexforming press in order to investigate the effect of geometric parameters on wrinkling. The results have shown that the wrinkling tendency increases with increasing flange length, and with decreasing contour radius, and sheet thickness. The experimental findings are then used to generate wrinkling limit diagrams in which safety and failure zones are specified for the different material conditions and sheet thicknesses. The developed diagrams can practically be used to design defect free parts, reduce scrap rates, and reduce production costs significantly.

Keywords: Flexforming; Sheet forming; Wrinkling; Convex contour flange