Automatic welding trolley for small pipes

The utility model provides an automatic welding trolley for small pipes, which comprises an outer machine shell, a mounting cavity is arranged in the outer machine shell, a straight swing motor is arranged in the mounting cavity, the output end of the straight swing motor is connected with a first straight swing synchronous wheel, and the surface of the first straight swing synchronous wheel is sleeved with a belt. A second straight swing synchronous wheel is installed at the end, away from the first straight swing synchronous wheel, of the belt, a straight swing screw rod is connected to one end of the second straight swing synchronous wheel, a sliding block connecting plate is installed on the surface of the straight swing screw rod in a threaded mode, straight swing sliding blocks are installed on the two sides of the sliding block connecting plate, and straight swing guide rails are slidably installed at the bottoms of the pair of straight swing sliding blocks. The pair of straight pendulum guide rails is