GB1155488A - Gas-shielded Arc Spot Welding - Google Patents

Abstract

1,155,488. Welding by fusion. AIR REDUCTION CO. Inc. 29 Aug., 1967 [6 Sept., 1966], No. 39449/67. Heading B3R. Gas shielded metal arc spot welding apparatus has a device for clamping the workpieces together adjacent the weld zone. A cylinder 29, mounted on a handle 35 or a fixed support, carries a C-shaped frame 20 formed in two parts 21, 22 adjustably interconnected. A consumable electrode 55 is fed by a remote device through the rod 48 of the piston 37 of the cylinder 29 to a contact tube 91 forming part of a welding head threaded into a block 60 which is a press taper fit in the end of the piston-rod 48. Gas, e.g. (argon or helium with, if desired, oxygen, or carbon dioxide) is fed through an inlet 62 in the block 60 to a two-part gas nozzle 80 having gas exit slots 82 and formed of chromium-plated brass. The nozzle 80 may be water cooled and is threaded to an insulating sleeve 76 secured by a screw 78 on the body 71 of the welding head. Current leads 67, 70 connect the welding supply via the block 60 to the contact tube 91 and via the frame 20 to a backing member 24 connected by a spherical coupling to the frame. During welding the piston 37 clamps the workpieces between the gas nozzle 80 and the backing member 24. In a modification, the electrode feeding device is mounted on the cylinder 29. The backing member, Fig. 6b, may be formed with a recess of circular or square section which is filled with weld metal to provide a reinforcing projection. A control device provided with four timers acting sequentially in response to actuation of a switch 36 causes air to be supplied to the cylinder to clamp the workpieces, and shielding gas and the electrode to be fed. The arc strikes when the electrode contacts the work and is terminated by burning back when the electrode feed is stopped. The gas flow and clamping pressure is maintained until the weld solidifies. The control device may be set to produce automatically a second weld at the same spot.