Camera-Based In-Process Quality Measurement of Hairpin Welding

The technology of hairpin welding, which is frequently used in the automotive industry, entails high-quality requirements in the welding process. It can be difficult to trace the defect back to the affected weld if a non-functioning stator is detected during the final inspection. Often, a visual assessment of a cooled weld seam does not provide any information about its strength. However, based on the behavior during welding, especially about spattering, conclusions can be made about the quality of the weld. In addition, spatter on the component can have serious consequences. In this paper, we present in-process monitoring of laser-based hairpin welding. Using an in-process image analyzed by a neural network, we present a spatter detection method that allows conclusions to be drawn about the quality of the weld. In this way, faults caused by spattering can be detected at an early stage and the affected components sorted out. The implementation is based on a small data set and under consideration of a fast process time on hardware with limited computing power. With a network architecture that uses dilated convolutions, we obtain a large receptive field and can therefore consider feature interrelation in the image. As a result, we obtain a pixel-wise classifier, which allows us to infer the spatter areas directly on the production lines.

Automated summary

Hairpin welding technology in the automotive industry requires high-quality welding processes, where defects can be difficult to trace back and spatter can have serious consequences. By implementing in-process monitoring and using neural network analysis of process images, a spatter detection method has been developed to early detect and sort out faults caused by spatter, ensuring weld quality. The network architecture utilizing dilated convolutions allows for feature interrelation consideration in the image, resulting in a pixel-wise classifier that can infer spatter areas directly on production lines.