This study first simulated the U-shaped micro bending of copper foil using the dynamic-explicit finite element method, and then analyzed the springback of unloaded copper foil using the static-implicit finite element method. The numerical analysis was conducted under the assumption that materials were isotropic in order to explore the relationship between punch load and punch stroke, deformation history, workpiece angle after unloading, springback amount, and sidewall curl. In addition, another U-shaped micro bending mold was designed for comparison, to verify that the finite element method proposed in this study can reasonably simulate the process of U-shaped micro bending.
This study explored the influence on changes in arc radius of die and spacer thickness on unloaded workpiece angle, springback amount, and sidewall curl. According to the results of the numerical analysis and experiment results, when arc radius of die increased, punch load decreased, and workpiece angle, springback amount, and radius of curvature near punch corner and die arc increased after unloading. Besides, when spacer thickness increased, punch load decreased, and workpiece angle and springback amount near punch corner also decreased after unloading, while workpiece angle, springback amount, and radius of curvature near die arc increased after unloading. The results of the numerical analysis and the experiment were consistent; thus the finite element method proposed by this study can effectively predict deformation and springback of U- shaped micro bending.