Welding device for welding large-scale pipe fitting elbow

The invention relates to a welding device for welding a large-scale pipe fitting elbow. The welding device comprises a lifting bracket, the bracket is connected with a welding arm, and a welding machine head is arranged on the end part of the welding arm. The welding device further comprises an elbow weldment clamping and fixing device, wherein the elbow weldment clamping and fixing device comprises a driving chain wheel, a first hydraulic oil cylinder, a first linear slide way and a second linear slide way, the driving chain wheel is driven by a driving chain to rotate, and correspondingly, adriven chain wheel is arranged on the inner side of the driving chain; the first hydraulic oil cylinder is connected with the driving chain, and can drive the driving chain to move up and down; and the first linear slide way, the second linear slide way and the driving chain wheel are arranged in a fan shape, the end parts of the two linear slide ways are hinged to a wheel shaft of the driving chain wheel, clamping and f