Side-wall thickness in draw die forming

The deformation of the side-wall of a sheet formed in an automotive draw die is studied using finite element analysis. The sheet is bent and straightened as it is drawn inwards from the blank-holder or binder; this causes significant thinning. Over the limited range of variables studied here, it is found that the thinning is inversely proportional to the die, or corner radius and that the increase in tension arises mainly from friction as the sheet slides over the die surface. The use of higher strength sheet to achieve weight reduction in auto-body panels makes stamping more difficult and the deformation of the side-wall is a critical and limiting factor that has not been extensively studied. The intent here is to introduce a technique for modelling that can be used to explore the influence of material and process variables on this forming operation.