Electric welding machine secondary extension cord connector

The utility model relates to an electric welding machine secondary extension cord connector. A plug comprises an inserting rod, a circular arc-shaped contact, a connecting pipe and a fastening strip, a screw hole is arranged on the upper surface of the connecting pipe, internal threads are arranged on the inner wall of the middle of a tubular socket, L-shaped fastening grooves are longitudinally symmetrically arranged at an insertion end of the tubular socket with the plug, a screw hole is arranged on the upper surface of the other end of the tubular socket, an insertion mechanism arranged inside the tubular socket comprises an conductive block, a spring and an adjusting nut, the spring is abutted to the conductive block, the adjusting nut abutted to the spring is provided with external threads, arc-shaped grooves are arranged on the sides, close to the L-shaped fastening grooves, of the conductive block, the arc-shaped grooves match with the circular arc-shaped contact, the adjusting nut is meshed with the i