Municipal pipeline nested welding machine

The utility model discloses a municipal pipeline nested type welding machine, which relates to the technical field of municipal engineering, and comprises a base and a rotary welding mechanism arranged on the base, the bottom of the base is provided with a stretching mechanism, the front end and the rear end of the stretching mechanism are respectively provided with a bundling mechanism, and the bundling mechanisms are used for fixing a pipeline; the rotary welding mechanism comprises a support, a middle shaft is horizontally arranged in the middle of the support, a middle shaft motor is connected to the middle shaft, welding frames are arranged at the two ends of the middle shaft, an upper sliding groove and a lower sliding groove which are parallel are formed in each welding frame, two racks which are oppositely arranged are arranged in the sliding grooves, and a gear is arranged between the two racks in a matched mode. A speed reducer and a servo motor are correspondingly arranged at the rear end of the ge