Flange compression using stepped punch for forming extremely deep cup with flange from aluminum alloy sheet

Abstract

This paper presents a method of flange compression using a stepped punch and die for effective production of an extremely deep cup with a flange from sheet metal. The proposed method was composed of initial stretching and flange compression, and fracture was prevented during the flange compression as the blank elongates by only compressive force. Optimum forming parameters, which are stepped lengths of the punch and clearance between the punch and the die, were investigated by finite element analyses and experiments. It was possible to produce a deep cup with uniform side wall thickness, which length-to-diameter ratio was 2.00, by the optimization of the forming parameters. In addition, two-step forming, which uses two punches, was proposed for producing an extremely deep cup with a thinner side wall. As a result, the deep cup, which length-to-diameter ratio was 9.23, was obtained.