Experimental investigation on laser flattening of sheet metal

The purpose of this research is to establish the technique of laser flattening and to consider the fundamental mechanism. The thermal stress produced by heating with a laser beam is used to make a flat sheet from a sheet metal of protruded distortion. Three kinds of protrusions are chosen as the typical protruded distortion; point protrusion, line protrusion and face protrusion. For point protrusion, laser irradiation along the circular path is effective when the height of protrusion is large, and the laser irradiation along the radial path is effective when it is small. For line protrusion, laser beam is irradiated along the short straight path whose direction is normal to the centerline of the protrusion. For face protrusion, the height decreases from 1–0.1 mm by the laser irradiation along the circular path. The residual stress at the convex surface of a point protrusion on the sheet metal changes from a large compressive stress to a small tensile stress by the laser irradiation.