Abstract: Through studying on the key technique of high efficient automatic welding for large scale spherical steel tanks, an automatic tracking system with CCD photo-detectors is developed to solve the problem of tracing multi-layer or multi-pass seams on real-time and an all-position welding carriage without rail, which can walk on the surface of spherical tanks, is created by using a flexible magnetic wheel mechanism. Moreover, the all-position welding technology is investigated with CO2 shielded flux cored arc welding (FCAW). Based on the above research work, an all-position welding robot with 5 degrees of freedom is developed to improve the automatic welding efficiency and quality of spherical tanks.

Key words: Automatic welding, High efficient welding, Spherical tank, Welding robot