Flaring Forming of Small Tube Based on Electromagnetic Attraction

Electromagnetic forming (EMF) is a kind of high-energy-rate forming technology which uses pulsed electromagnetic forces to achieve rapid plastic deformation of workpieces. It can significantly improve the forming limit and formability of light-weight alloys and has been widely used in the field of tube forming. However, in the existing tube forming systems, the electromagnetic force between the tube and the coil is mainly dominated by a repulsive force. When flaring the tube, the coil must be placed inside the tube, which is not suitable for the forming of small tubes. In order to solve this problem, a method of flaring small tube with an outer coil is developed, where the coil current is generated by a dual-power supply system and a significant attractive electromagnetic force between the coil and the tube is produced for flaring forming. The feasibility of the method has been demonstrated by both numerical simulations and experiments. It has been shown that the flaring of an A1060-O aluminum alloy tube with diameter of 20 mm can be successfully realized, and the maximum radial deformation is about 4.88 mm. Meanwhile, it has been pointed out that the performance of tube flaring can be further improved by changing the relative position of tube and coil and the discharge voltage value of the dual-power supply system. The obtained results provide a new flaring tool for small tubes and expand the application of electromagnetic forming technology in tube processing.