Design and Construction of Loading System and its Dynamic Property

Optimization of Lading System in High-Current Density Spot Welding (1st reprot)

Abstract

In a high-current density spot welding, the large electromagnetic force yields between electrodes. This electromagnetic force bring about the fluctuation of the loading force, and then, it has some adverse effect on weldability. The fluctuation of the loading force is changed by stiffness, friction, or response of a loading system. In this report, we designed a loading system which is able to control the movement of an electrode, and clarified the dynamic property in turning on electricity. The loading force is affected by the electromagnetic force and the thermal expansion. The electromagnetic force increases proportionally to the square of the maximum current in the reverse direction of loading, and as a consequence, it reduce the actual loading force to the specimens. The electrode movement is controlled by a stopper and a spring assembled into a loading system. In a rigid loading system with large spring constant, the electrode movement by the electromagnetic force is restrained, and so the loading force is increased by the thermal expansion. The other hands, in a loading system with small spring constant, the loading force is decreased, because the electrode movement caused by the electromagnetic force is larger than the thermal expansion.