Finite Element Study on Pattern of Pins Supporting an Elastic Blankholder Used for Stamping Irregular Shaped Sheet Metal Parts

Abstract

Working with individual in-process controllable elements to support an elastic blankholder is the state-of-the-art for stamping irregular shaped sheet metal parts without wrinkles and cracks. It is thus needed to carefully determine the position for each expensive device. This study is therefore aimed to appraise a feasible approach with finite element analysis, in that the blankholder is first modelled as a rigid object instead of an elastic one to evaluate the contact pressure of the blankholder to the blank during the forming process. The sites showing a locally relative high contact pressure, which are usually induced by local thickening of material, can be regarded as the locations of the supporting elements to intently form a local high pressure to control the material flow and thus to eliminate the local thickening there. As a result, since the blankholder force can be efficiently delivered from the supporting elements directly to the blankholder as well as to the blank, it is not only applied to the rectangular box-shaped part but also to a fender-like irregular sheet metal part. Furthermore, the initiated contact pressure can be maintained at locations during the whole stamping process. This is also experimentally validated by stamping a sound fender-like irregular sheet metal part with an elastic blankholder supported by elements located accordingly at those sites suggested by this study.