Experimental investigations of the electromagnetic pulse-assisted incremental drawing of aluminum alloy

Abstract

During the drawing process, when the radial tensile stress is greater than the limit of the sheet metal’s bearing capacity, the workpiece will rupture. In order to succeed in forming the cylindrical part, it is necessary to reduce the radial tensile stress, or even change the tensile stress into compressive stress. In the current study, electromagnetic pulse-assisted incremental drawing (EMPAID) technology was used to form the cylindrical part, which can generate magnetic force on the flange material, which pushes them to flow into the die cavity. The drawing coil with different turns matching the determined corner coil and different auxiliary coils were used to conduct the experiments. When the two-turn drawing coil, one-turn corner coil, and two-turn auxiliary coil were used, after multiple times of discharge and micro-shaping, the limit of the drawing height of the formed part increased to 42.86 mm, which was 2.16 times of the limit drawing height obtained using the conventional drawing. Using the three-turn drawing coil combined with the corner coil and four-turn auxiliary coil to carry out the experiments, the cylindrical part’s maximum drawing height reached 63.72 mm. Meanwhile, the flange area was almost completely converted into the cylinder wall. When the dense winding auxiliary coil was used to conduct the experiments, the maximum forming depth was only 25.24 mm. The experimental results showed that during the forming process, majority of the flange material was pushed into the die cavity due to the action of magnetic force. Due to this reason, the thinning of the forming part can be suppressed. If the magnetic force generated by the drawing and auxiliary coils matched reasonably, then the depth of the formed part can be improved significantly.