Patent GB-507640-A (GB)
Title: Improvements in or relating to means for electrically welding metallic projections onto metallic tubes
IPC: B23K11/00
Filed: 1937-12-17
Abstract: 507,640. Welding projections to tubes. BABCOCK,& WILCOX, Ltd. Dec. 17, 1937. No. 35023. Convention date, Dec. 28, 1936, [Class 83 (iv)] A portable apparatus for electrically welding projections; such as studs, to a tube, particularly a tube arranged in situ in a boiler, comprises a support fixed on the tube on which is adjustably mounted a tool for advancing the studs towards and electrically welding them to the tube, the apparatus including an indexing device for positioning the tool in successive locations for welding the studs in predetermined relation to each other. The welding apparatus 12 is adjustable on a rack bar 2 provided with bolts 8 passing through arcuate slots in the flanges 6 of angles secured by clamps 3, 4 to the tube 1, so as to permit of angular adjustment of the tool to space the projections circumferentially of the tube. The rack bar may be held in adjusted position by springs 9. Spacing plates 11 may be secured on the rack bar. After a number of studs in a longitudinal row have been welded to the tube an upper clamp 4 is substituted at the top end for an open-ended clamp such as 3. The welding apparatus may comprise contacting toggleoperated hand tongs 22 provided with recesses 23 to receive the studs so as to weld a pair of studs simultaneously on opposite sides of a tube situated in a row of tubes. The tongs may be of the expanding type as shown in Fig. 4, to weld two studs simultaneously to adjacent tubes. The tongs are carried by a < slide 13 which is held in adjusted position longitudinally on the rack bar by a spring- pressed toothed block 14 and is vertically adjusted by a pinion 17 operated by a hand lever 18 through a similar spring pressed block. The frame may be provided with cable suspension and counter balance. In order to obtain rows of welded studs extending over more than half the circumference of each tube of a number of parallel tubes, a separate apparatus is used for welding the studs in positions intermediate the opposed studs 28, 29, Fig. 6, which are applied by the previously described apparatus. This apparatus comprises angle members 35, 38, Fig. 5, secured across a number of parallel tubes 27 by bolts 42, rear bars 41 and recessed spacers 53. On the members 35, 38 are secured bars 45, 46 which serve as transverse guides for a pair of slides 47, 53 in which a ratchet bar 34 carrying the welding tools is mounted. The portion 47 of the upper slide is provided with rollers 48 running on a plate 50 secured to the angle 35. The parts 53 are bolted to the parts 47 through bosses 56, 57 to leave recesses for plates 58, which are secured by screws to the ends of the ratchet bar 34. Rollers 60 on the screws engage in curved slots 59 in the parts 53 to provide for circumferential adjustment of the tools. The slides are fixed in required position opposite one of the tubes of a row by pins 63,engaging holes in the parts 45, 46. The welding tools consist of a pair of pneumatically operated hollow electrodes 30 for holding studs and carried by separate cylinders 31 secured to a frame 32 which is fed step by step along the ratchet bar by a hand lever 82 pivoted at 84 to the frame 32 and carrying a spring-controlled pawl 87 engaging the ratchet teeth. When the lever 82 is pushed down the frame 32 is raised and the holding pawl 80 moved out of contact with the teeth. The latter is subsequently returned by gravity. Current may be conducted to the electrodes by separate conductors 75 so that the current passes in series through the studs and tube, but for welding a stud singly one electrode is connected to one terminal and the tube to the other.