Application Study of Edge Detection for Droplet in Laser Enhanced GMAW Welding

Ambient pressure has a certain inhibiting effect on underwater welding droplet transfer and the stability of welding process. Good droplet transfer of underwater welding plays an important role in improving repairing quality of underwater structures. As an additional droplet separating force, laser provides effective means in improving the welding quality. For quantitative analysis and comparison of laser enhanced effect on droplet transfer, a high-speed camera system to shoot the process of welding droplet transfer was designed and by adopting the frequency domain operation, a filter aiming at image processing of welding droplet was also designed to filter the ambient noise and diffraction fringe. Through edge detection algorithm, edges of droplet images were detected, and the size of droplet was computed accurately with welding wire as the reference. At last, droplets’ statues under different welding parameters were compared. The results show that the clear images of GMAW droplet separated from the noise background can be acquired, which makes the high-precision quantitative analysis of laser enhanced effect possible. All of the results lay a foundation for further test of laser enhanced hyperbaric underwater welding.