Flange butt welding machine and welding process thereof

The invention discloses a flange butt welding machine and a welding process thereof, relates to the field of flash butt welding machines, and solves the problem that clamping stability and welding precision are affected by long-time abrasion of a single part of a clamping part when an existing flange butt welding machine and a welding process thereof are used, the flange butt welding machine comprises a machine body, a welding mechanism, a switching mechanism and a grinding mechanism, a first device box and a second device box are arranged on the machine body, the welding mechanism comprises a fixing box and a lifting box, the fixing box and the lifting box are each provided with a clamping disc, the switching mechanism comprises a threaded shaft, and the polishing mechanism comprises a polishing rod. Flange clamping and collision flash welding operation is achieved, the switching mechanism is in linkage with the threaded shaft to rotate by a set angle, fine adjustment of the positions of the clamping discs i