Large area micro bending method by soft punch under laser shock wave based on multi-groove mold

To implement the large area micro bending forming of metal foils, this paper presents a large area micro bending method by laser shock wave based on advantages of laser shock bending forming and soft punch forming. With this method, the metal sheets would be deformed under the soft punch. In the experiments, a pulse Nd-YAG laser (Innolas Gmbit Spitlight 2000 THG) with Gaussian distribution beam was employed, and the polyurethane rubber with a thickness of 250 μm were used as the soft punch. The U-shaped grooves with a depth of 120 μm were machined on a printed circuit board with an engraving machine made in Germany (LPKF-ProtoMat-C60). After one impact, three U-shaped grooves were replicated from the mold on cooper foils with a thickness of 30 μm. Observed by the digital measurement system (KEYENCE VHX-1000C), the deformed micro grooves in the work piece own good contour shape. Besides, the numerical simulation was used to understand the micro-bending process by the ANSYS/LS-DYNA software. The experiment and simulation results show that the work pieces with soft punch have more uniform multi-groove contour shapes and good surface quality. The depth of the deformed micro grooves in the work piece reaches as deep as 110 μm, higher than that from the laser direct shock shape (88 μm). Therefore, it implies that this kind of process improves the work piece forming ability and quality.