Large-scale sheet deformation process by electromagnetic incremental forming combined with stretch forming

Large-size sheet parts manufacturing requires huge forming machines in spinning and sheet hydroforming. In addition, large part cannot be shaped by conventional electromagnetic forming method due to the limitation of the strength of working coil and the capacity of capacitor bank. In this paper, a new method denoted as electromagnetic incremental forming combined with stretch forming is proposed, which was adopted for manufacturing large-size and thin-walled ellipsoidal parts. A 3D finite element model is established to analyze the effect of the number of coils, coils moving path on forming quality. The effect of the subsequent deformation on deformed sheet region, material flowing and the distribution of stress in special elements are also discussed. Then, the experimental platform designed based on FEM is used to manufacture the large-size parts after 36 times discharging and 6 times stretching. The simulation has a good agreement with experiment results. In comparison with single point incremental forming, the thickness thinning is sharply decreased using the new method.