Development of gap sensing system for narrow gap laser welding

Narrow gap welding with oscillation laser beam is one of the effective processes for thick plate welding. To put this welding process into practical manufacturing, a groove sensing system is required for preventing the welding defects, especially lack of fusion. In this study, we have developed a real-time groove sensing system using the image processing for narrow gap welding with oscillation laser beam. This developed system uses still image of weld zone taken by coaxial CMOS camera. It can recognize the position of the groove wall by analyzing the brightness distribution in the still image. And then it can control the oscillation width and the laser irradiated area by calculating the groove width and the groove center position. Some narrow gap welding experiments were performed to evaluate the performance of the developed system. The results revealed that the developed system is effective for narrow gap welding with oscillation laser beam. By using this system, the narrow gap groove can be weld even if the groove width has changed during welding process.