Evaluation of welds of aluminum alloy AA6022-T4 welded using an electrode force changeable resistance spot welding machine

摘要

Resistance spot welding (called spot welding in the following) is used widely in industry, particularly in the automobile industry. In spot welding, welding is typically done with the flow of a fixed current for a fixed period of time, based on a fixed electrode force that is set initially. However, the increase in temperature, expansion, softening, transformation and melting after the application of the electrode force and the hardening, cooling and contraction, after that force is stopped, are accompanied by moment by moment changes in the electrode force at the weld. The authors have developed a resistance welding machine that incorporates a mechanism with which the electrode force can be changed instantaneously, while the current is being applied. When spot welding was carried out on SPCC cold rolled steel sheets using this welding machine, it was possible to form excellent nuggets by lowering the electrode force from the base electrode force, while current was being applied, and it became clear that the maximum tensile shearing force for spot welded joints was obtained with this.