Modelling the effect of misalignment in conventional and non-conventional deep drawing tools for more resilient cup production

Deep cup-shaped products of cold rolled sheet metal are produced by multiple deep drawing stages. Adjusting the tooling during production for a product or material change can only be carried out by appropriately trained and experienced employees. One reason for the complexity of the tool change is the static overdetermination of the tool system which leaves no degree of freedom for the punch. Therefore, the alignment of the punch to the die has to be very precise. Coaxial misalignment induces changes in wall thickness distributions concerning the circumference of the cup, leading to defects. To reduce the effort for reconfiguration, a tool concept for a deep drawing tool for circular parts is presented, which can compensate the inaccuracies in the alignment with guidance near the forming zone. In this finite element (FE) simulation study, the effects of coaxial misalignment and alignment of the punch and the die on both tools are modelled. The results of the wall thickness distribution is then compared and evaluated. Furthermore, the validity of the results is determined through a experiment on a deep drawing demonstrator. The approach offers the potential for a reduction in both set-up time and the number of defective cups with deviating wall thicknesses, which results in a more resilient production of cup-shaped products.