Design and implementation of tube bulging by an attractive electromagnetic force

The application of an attractive electromagnetic force for small tube bulge forming is a meaningful but challenging issue because it is almost impossible to do so with the traditional electromagnetic bulging method, in which the electromagnetic force is always repulsive. A new method has been proposed to solve this problem, in which an attractive electromagnetic force was generated by controlling the discharge current in a high strength forming coil with two pulse width power systems. To validate the effectiveness of the expanding tube by an attractive electromagnetic force, electromagnetic bulging equipment has been designed and manufactured. A series of simulations and experiments have proven that the attractive electromagnetic force can effectively expand the tubes. As shown in the obtained results, an annealed 1060 aluminum tube with a 28 mm inner diameter and a 1 mm thickness can be attracted towards a coil with a maximum height of approximately 2.55 mm and with a strain in the middle area of the tube of more than 15%. The method and results presented here will facilitate the development of electromagnetic forming systems.