Abstract
A visual sensing system for in-process control of arc welding process is constructed by the combination of He-Ne laser and interference filter with narrow width at half maximum (WHM: 1.0 nm). By adopting a polygonal mirror in this visual sensing system for scanning of laser spot light, the variation in intensity of laser slit-like light has been decreased by a large margin.
Using this visual sensing system, the gap width of I groove and weld line can be detected easely near molten pool without disturbance of powerful arc light, and the time for detection of groove information is only 36 ms. The error in detection of groove information is less than 0.05 mm, and the limit of detection is about 0.1 mm.
On the other hand, it is proved experimentally that the detection is not influenced very much by the errors in measurment or angle in making I groove is proved experimentally.
This visual sensing system has been applied to automatic weld line tracking at TIG arc welding process in real time. In this case, one cycle of weld line tracking is about 0.2 second and the error in tracking is less than ±0.4 mm.
