Abstract
A lithium ion battery bank used for electric vehicles is composed of many cells and current-collector tubs, and a large current passes through the tubs from the bank and flow to a motor. Moreover, a joining method for multi-stacked aluminum sheets is required. In this paper, we present a magnetic pulse welding method for five aluminum sheets with four gaps and a measurement method for four collision time signals. The four signals are simultaneously measured with two oscilloscopes. The five sheets used are of same thickness. An experiment is performed on 0.3, 0.5, 0.8 and 1.0mm thickness respectively. The first sheet on a plate coil experiences only an electromagnetic force, but the second sheet on the coil experiences both an electromagnetic force and an impact force by collision with the first sheet. Therefore, the time it takes for the second sheet to collide with the next sheet is always shorter than that for the first sheet. The five aluminum sheets were seam-welded along narrow middle of the coil. In a shearing tension test, five seam-welded sheets of 0.5mm thickness obtained at 3.5 kJ did not come off on four joined interfaces corresponding to the four gaps, but fractured in the five sheets. When all collisions generated in the four gaps are finished within a first wave of electromagnetic force, the five sheets may be strongly joined.
