Influence of process parameters on the formability of bead stamping part using advanced models

Beads are applied to deep drawn sheet metal parts to increase its stiffness. In order to form the bead, a two-stage manufacturing process including at least deep drawing and beading is performed. Thus, reductions of sheet metal thickness and consequently weight reduction can be effectively reached by numeric optimization. In order to apply the optimization algorithm to the production of non-virtual actual parts, the forming limits of the parts must be considered in both manufacturing steps. Bead formability is affected by process parameters such as blank holding force and lubrication. One way to investigate these influences is to use an accurate simulation model. In this study, the yield function named Yld2000-2D under non-associated flow rule is used to express anisotropic material behavior of blank and the Generalized Forming Limit Concept (GFLC) considering nonlinear strain paths is used to determine the formability. These models are validated by comparing the strain and bead forming limits measured in the Nakajima experiment. Then, the influences of mentioned process parameters are investigated by the validated model.