Effect of pulsed laser parameters on deformation inhomogeneity in laser shock incremental forming of pure copper foil

Abstract

The dependence of deformation inhomogeneity on the pulsed laser parameters in laser shock incremental forming (LSIF) of pure copper foil was studied based on finite element simulation. The formed depth, angle, profile and limiting fluctuation value were adopted to evaluate the forming deviation of parts. The digital microscope was employed to examine the bottom surface morphology of formed parts. The effect of pulsed laser energy, spot diameter and overlapping rate on the deformation inhomogeneity in LSIF was investigated. It is revealed that there are variances in the shape and dimension of formed parts along both the shock and travelling directions owing to the local loading history of LSIF. The formed depth and angle are different in various positions of formed parts along the shock direction, while the formed profile presents a periodic variation along the travelling direction. The appropriate enhancement of laser energy can improve the deformation inhomogeneity along both the shock and travelling directions. The deformation profiles along the shock and travelling directions depend on the adopted spot diameter. The rebound effect may occur while too small spot diameter is employed, resulting in the degradation of forming accuracy. The overlapping rate has a major impact on the surface morphology of formed parts. As the overlapping rate increases to 80%, the limiting fluctuation values along the travelling direction become large due to the distortion at the free end. Under the given process conditions, the laser energy of 1100 mJ, the spot diameter of 2.5 mm and the overlapping rate of 60% are recommended to achieve straight-line channels with high forming quality.