Self-circulation water-cooling ultra-narrow gap MAG/MIG welding gun based on contact-surface-free heat conduction

The invention relates to a self-circulation water-cooling ultra-narrow gap MAG/MIG welding gun based on contact-surface-free heat conduction. The welding gun comprises a welding gun base component, an ultra-narrow gap water-cooling nozzle component, a water intake/return valve component, a sealing component and a cosmetic bead nozzle, wherein the ultra-narrow gap water-cooling nozzle component, the water intake/return valve component, the sealing component and the cosmetic bead nozzle are connected with the welding gun base component in a matching way respectively. The welding gun has the advantages as follows: 1, a self-heating component and a component, of which the exterior is easily subjected to radiation and convection heating, are completely free of contact-surface heat conduction during a welding process, all heat is directly transferred to a circulating water flow channel via a pure-copper integral structure with favorable heat conductivity, no component is locally heated during long-term operation in a high-temperature environment, the whole welding gun always operates at a uniform lower temperature, and the welding process stability and the wire feeding stability are extremely high; 2, the service lives of the welding gun and a contact tube are greatly prolonged; 3, an internal filling bead and the cosmetic bead nozzle can share one welding gun base and be exchanged quickly and very conveniently; and 4, the welding gun can be used for ultra-narrow gap MAG/MIG welding or narrow gap MAG/MIG welding.