There are two models,Agantry type automatic welding machine and T double colum-beam automatic welding machine. It adope A.C. inverter control, with functions of stable running and fasting travelling speed; the seam-tracking arc-guide mechanism is three-spindle system to guarantee the alignment without aberrancy; The main frame and welding machine are integrated control, with flux auto-recovering system and it is easy to operat with high efficiency. T double columm-beam automatic welding machine can weld two pieces of beam at the same time, and the web height of beam is not limited by main machine.