Abstract: The central concern in forming U-shaped parts is the effect of springback on the geometry. Variable blankholder force reduces springback. But there is no method for determining blankholder force trajectory. Proposed here is an optimization design for variable blankholder force. It combines orthogonal design of an experiment with FEM software. The method is validated numerically using FEM to simulate the benchmark of 2-D draw bending problem in NUMISHEET’93. Cracking was eliminated and dimensional accuracy improved to yield a higher forming quality. Simulation cycles are also minimized. In all, this optimization approach attained a new level of efficiency in several areas.

Key words: Accuracy, FEM, Orthogonal design of experiment, Stamping, U-shaped part