Method of Reducing Residual Stress Generated by Laser Cutting by Light Indentation of Sheet Metal Edge

Laser cutting has started to be used as an effective method for cutting out blanks from rolled sheet metals because of its high flexibility for cutting line and high productivity. However, residual stresses, which are generated by laser cutting, have been the greatest obstacle for the popularization of laser cutting. One of the problems is the warp which appears in the sheet metal, after being subjected to bending processes after laser cutting. The authors present a light indentation method for reducing residual stress generated by laser cutting. The method is to give light indentation on the sheet metal edge and to reduce tensile residual stress generated near the laser cutting surface. In particular, this present paper especially focuses upon optimization of working condition depending on mechanical properties of blank. Furthermore, the mechanism of transition of stress and effective strain in light indentation was examined. Experiments of U-bending after applying light indentation were conducted for usability of this method. The FEM analyses were carried out in order to investigate the effect of working condition in various mechanical properties. As a result, the optimum condition of light indentation method in various materials was found out, and the warp of bent sheet metals was drastically reduced.