Contribution of Process Parameters to Geometric Deviations of the Robot for Continuous Ultrasonic Welding Process of Thermoplastic Composites

Over the last years due to the growing significance of thermoplastic composites, continuous ultrasonic welding as one of the most feasible fusion bonding technologies has gained attention in the aviation industry. The greater flexibility and ability of industrial robots to weld complex components than welding machines make them more suitable for the ultrasonic welding process. However, they suffer from lower structural stiffness and lower absolute accuracy in terms of the serial kinematic. Moreover, robots interact with the process differently. Applied process forces act as additional disturbance variables and influence the robot's accuracy. A high-quality weld line requires the careful selection of the process parameters, accurate movement of the end effector, and ensuring the key criteria during the welding process, such as proper alignment of the sonotrode with respect to the adherends. Depending on the selected welding parameters and the resulting dynamic forces during the process, geometric deviations from the desired motions can occur, which negatively impacts productivity. Obtaining appropriate knowledge about the robot's behavior and determining how the ultrasonic welding process interacts with the robot is necessary to meet the strict manufacturing tolerances required in the aviation industry and ensure reproducibility. This work aims to understand the interactions between the robot and the welding process by investigating the effect of process parameters on geometric deviations of the robot.