Patent GB-1282461-A (GB)
Title: Method and apparatus for fire cracker arc welding
IPC: B23K9/14
Filed: 1969-07-08
Abstract: 1282461 Welding by fusion SUMIKIN WELDING ELECTRODE CO Ltd 8 July 1969 [8 Aug 1968 13 Aug 1968 19 Aug 1968 20 Aug 1968 31 Aug 1968 (2) 19 Sept 1968 28 Nov 1968] 34431/69 Heading B3R [Also in Divisions C7 H1 and H2]  In "firecracker" arc welding, wherein a consumable electrode 4 having an insulating flux coating is disposed along a welding line 3 and an arc is started between one end of the electrode and the workpiece and travels along the line as the electrode melts, circuit-completing contacts made directly with the welding electrode core at flux-coating-removed spaced positions therealong are successively broken. In Fig. 1, contacting members 6, 61 engaging the electrode core through flux-coating recesses 8, 8<SP>1</SP> are successively withdrawn by means responsive to arc proximity. Such means may comprise a photo-electric cell, photoconductor, phototransistor, photodiode or photovoltaic cell sensing arc light. In Figs. 2 and 3 (not shown) a cadmium sulphide cell is arranged to operate a contacting member withdrawing solenoid (16). Spring-loaded contacting members may be released, via systems of levers, by solenoids responsive to a photo-electric cell sensing arc light (Fig. 4, not shown), or by means e.g. a bimetal sensing arc heat (Figs. 5-7, not shown). In Figs. 8-11 (not shown), the welding electrode has a V- or U-shaped longitudinal groove (66) in the periphery of its core wire (67). By placing the electrode so that this groove is directed away from the workpiece, melting of the flux coating on the groove side is delayed and directivity and stabilization of the arc are thereby enhanced. Arc directivity may be further enhanced, and the electrode may be attracted to the workpiece, by including in the flux coating a magnetic powder of oxide, e.g. powder of BaO.6Fe 2 O 3 , or metal. Arc directivity may be again increased by including in the flux coating a large amount of high melting point substances e.g. powder of CaCO 3 , MgCO 3  or Al 2 O 3 . Example flux ingredients include SiO 2 , TiO 2 , Na 2 O, K 2 O, Al 2 O 3 , CaCO 3 , MgCO 3 , Fe-Mn, Fe, BaO. 6Fe 2 O 3 , CaSiO 3  and permanently magnetic powder. In Figs. 15, 16 (not shown) a plurality of arc welding electrodes of the different size are bound together for placement in the welding preparation. In Figs. 17-19 (not shown) the core wire and coating of the electrodes are shaped to conform to the shape of the welding preparation. Electrodes may be joined end-to-end byinner cores engaged in adjacent core wire recesses (Fig. 20, not shown), by core wire spigots engaged in core wire recesses (Fig. 21, not shown), or by core wire spigots engaged in flux-coated connecting sleeves (Fig. 22, not shown). In Figs. 23-25 (not shown) the electrodes are held in position by weights of copper or copper alloy 5-50 mm. long. Such weights may be attached to the workpieces by having permanent or electromagnets fixed thereto. Magnetic backing bars for one-sided buttwelding may comprise compressed and moulded magnetic powder of an oxide and/or metal, e.g. less than 80% of one or more of high melting point oxides such as alumina or magnesium oxide, copper, iron and iron alloys, and deoxidizers such as ferro-manganese, ferrotitanium and ferro-silicon, mixed in a magnetic powder of such oxide as BaO. 6Fe 2 O 3  or cobalt ferrite. The backing bars may be solid (Figs. 26, 27, not shown); may comprise covered core wires (Figs. 28, 29, not shown); may comprise one or two side layers of magnetic substance (Figs. 30-32, not shown) or may be made by dispersing a magnetic powder in rubber or thermoplastic or thermo-setting resin.