Potential of using of ultrasound technology to support resistance spot welding of metal - polymer composite

In this work the application potential and welding issues of Metal-Polymer Composite were presented. The necessity and methods of removing the polymer layer from the joint area have been described. The potential of using the ultrasound technique (UT) to plasticize the polymer fraction to ensure current contact between the steel sheets was indicated. In the example of resistance spot welding (RSW), the possibility of coupling the welding process with an ultrasonic support was shown. The mechanism of transmission of ultrasonic waves into the polymer layer has been described. The process of designing a tool for ultrasonic support of selected bonding techniques was characterized. For this purpose, modal and harmonic analysis was carried out to develop the geometry of sonotrode. FEM numerical tests were performed using ANSYS Workbench software. Two types of heating mechanisms were analyzed: through internal friction of polymer particles and friction of the sonotrode against the material surface. On this basis, the heating curves of polymer layer were determined. The developed vibrating system was integrated with a stationary RSW gun. A system with a transducer frequency of 20 kHz and a power of 3 kW was used. Finally, RSW-UT technology was used to join MPC composites to DP600 steel and it was found to be capable of producing high-quality joints without structural defects.