Investigation on the interfacial behavior of hybrid ultrasonic resistance welding

It is difficult for ultrasonic welding (USW) to be applied in the joining of miniature work pieces. This challenge results from the area of the weld tip, which limits the ultrasonic power delivered to the weld zone. A new hybrid welding technique, the hybrid ultrasonic resistance welding (HURW) technique, is proposed to contribute further to the improvement of ultrasonic welding quality. In the HURW, a synergic effect is obtained from the two different kinds of welding energy, which takes advantage of the beneficial aspects of each process and minimizes the shortcomings of each other. HURW of 6061 aluminum alloy to pure copper is investigated via comparison with the USW process under the same welding condition. Experimental results show that in HURW, the peak power of ultrasonic vibration increases significantly, and more energy is delivered into the weld zone due to the resistance welding current. As a result, the peak temperature and the heating rate of the interface increase remarkably. However, because of the ultrasonic vibration, the interface contact resistance decreases and disappears rapidly at the initial stage of the process. This will minimize the resistance heat.