Automatic welding device for U-shaped rib plate

An automatic welding device for a U-shaped rib plate is used for welding a U-shaped ring and the U-shaped plate. The device comprises a frame, a pair of longitudinal guide rails is arranged on the frame, and a longitudinal travelling crane translating in the longitudinal direction is arranged on the pair of longitudinal guide rails; the longitudinal travelling crane is provided with a transverse guide rail, a transverse travelling crane translating in the transverse direction is arranged on the transverse guide rail, and a steering lifting mechanism is connected to the transverse travelling crane; the steering lifting mechanism comprises a rotating shaft which is vertically arranged, the upper end of the rotating shaft is rotationally connected with the traverse vehicle, and the lower endof the rotating shaft is slidably connected with the welding machine hanging bracket; the welding machine hanging bracket is provided with a horizontal shaft, a welding gun base is connected to the horizontal shaft in a slidi