GB1321885A - Welding gun for semi-automatic welding - Google Patents

Abstract

1321885 Welding by fusion R OGDEN SNR 2 July 1970 [2 July 1969 3 June 1970] 32180/70 Heading B3R In a consumable wire-electrode arc welding gun comprising a curved wire-guiding barrel 40 adjustably and releasably secured to a handle 26, a contact tube 14 is received within longitudinally extending fingers (66) of a collet 52 fast with the barrel, the collet is embraced by a longitudinally split, contractible, electrically insulating, heat transfer sleeve 24, and the latter, in turn, is embraced by longitudinally extending fingers (102) of a jacket, such as a gas nozzle 16, the arrangement being such that on tightening of a surrounding clip, such as a screwactuated garter 18, the contact tube and jacket are simultaneously releasably secured to the barrel. In the MIG gun shown, the electrically insulating sleeve 24 serves to conduct heat from the gas nozzle 16 to the barrel 40 which has longitudinal fins (22) to dissipate contact tube and gas nozzle heat. The barrel and the sleeve 24 may be of aluminium coated with aluminium oxide or epoxy resin. The collet 52 and a similar collet 54 are threadably secured to opposite ends of the barrel. Opposite ends of the sleeve 24 are abutted by a protective, electrically insulating sleeve 94, e.g. of silicon rubber, enclosing one end of the collet 52, and a heat resistant, electrically insulating, plastics gas diffuser 80 provided with gas discharge holes 87. The diffuser 80 has radial projections (83, 81, Fig. 10A, not shown) engaging and loosely circumferentially relatively locating the sleeve 24 and the collet 52. The contact tube or, Fig. 11 (not shown), the diffuser 80 may be provided with a spatter guard, such as 95. The gas nozzle 16 may be of aluminium, copper or brass. The internal surfaces of the collet fingers (66) are preferably copper or silver plated. The arrangement shown is suitable for carbon dioxide, but where an expensive gas such as argon is used a rubber seal (91, Fig. 11, not shown) is provided between the diffuser 80 and the sleeve 24. The barrel comprises a wire guide tube 44 which, as shown, has openings 75, for gas flow therethrough, adjacent the contact tube. The handle 26 comprises two plastics (e.g. glass fibre) sections 132 bolted together at 134. At the barrel end, the handle comprises longitudinal fingers (178) embracing fingers 126 of the collet 54 which in turn embrace an adapter tube 144, the handle, barrel and adapter tube being releasably secured together by tightening of a surrounding clip such as a screw-actuated garter 28. At its end remote from the barrel, the handle is provided with a cap 138 having protuberances (173) for snap engagement with the handle. The adapter tube 114, e.g. of aluminium or copper, has a hardened steel liner 286 and is threaded at 145 to receive a gas inlet connector 37 (e.g. of nylon) and a cable fitting 146. The latter receives a cable 29 comprising a wire guide helix 152 and a current conducting copper wiring 154. A switch 192 connected to the welding machine by way of leads 197, 199, 211, 213 and pin-and-socket connectors 203, 205, 207, 209, is actuated by a spring-returned trigger 214. Gas flow is through a conduit 30, the connector 37, adapter tube 144, wire guide tube 44, opening 75, slots 122 between the collet fingers, and the diffuser holes 87. Welding current is taken to the electrode through the cable 29, adapter 144, the barrel and the contact tube. In a gun for smaller wire electrode (Fig. 14, not shown), gas is conveyed via adapter tube and barrel channels surrounding the adapter tube liner 286 and the wire guide tube 44. In guns for use without shielding gas, e.g. with flux-cored wire, the jacket surrounding the sleeve 24 may, for long electrical stick-out (Fig. 17, not shown), enclose a ceramic wire-guiding liner, or, for short stick-out (Fig. 18, not shown) serve merely to hold in place a filler element replacing the gas diffuser.