Patent GB-1283481-A (GB)
Title: Welding by high frequency current penetration
IPC: B23K13/04
Filed: 1970-01-21
Abstract: 1283481 Welding AMF Inc 21 Jan 1970 [21 Jan 1969 (2)] 2909/70 Addition to 1147439 Heading B3R A high-frequency current is caused to penetrate and flow along a predetermined path through two metal portions to be joined, a contact with the current source being established at one end of the current path, at the other end of which path contact is established with a conductor overlying in close proximity the desired current path, which may be straight or curved, whereby current flows in one direction through the metal portions and in the other through the proximity conductor, the proximity of which controls the depth of penetration of the current through the metal portions in accordance with the frequency, so that the metal portions are heated and upon the subsequent application of pressure are forge welded together. As shown in Fig. 1, a connection is made at 3 between the metal portions 1, 2 and the current source 5, a further connection being made at 6 with the proximity conductor 7. The current flow path is shown at 8, Figs. 3 and 9, Fig. 4. The process may be applied to the welding of sheet metal seamed and other joints, Figs. 11, 13, 15 and 17. Contact between the current source and proximity conductor and the metal portions may be made at the ends of the current path below the metal portions or above one of them, Fig. 18. The ends 52, 53, Fig. 19, of the proximity conductor may be widened to prevent overheating in this vicinity, and the proximity conductor may be shaped to give two flow paths, Fig. 22. The proximity conductor 7 may be offset, Fig. 21, and the ends of the metal portions held between an anvil 56 and a hammer 57 by means of which pressure is applied simultaneously with or subsequent to the heating. The width of the current path may be reduced by disposing a magnet at least partly around the proximity conductor from which it may be insulated, or the proximity conductor may be disposed within a forging bar which may be partly surrounded by a magnet. In Figs. 25 and 26, a can body to be seam welded is placed upon a mandrel 75 and copper anvil 76 connected to a terminal bar 84 having a cooling device 87. The proximity conductor 7 is hollow and extends through a contact bar 83 for the circulation of a cooling fluid and also extends through an elongated opening 80 in a non- conductive forging bar. Pressure is applied during heating by a spring 86 and subsequent forging pressure, if necessary, applied through a shaft 81. The bar 76 is in contact with the can body over its whole length, but in a modification, contact areas are arranged only at the ends. In further embodiments, there are two proximity conductors, which may both be on the same side of the metal portions or one on each side. In Fig. 36, a metal can body is heated at one location and forged at another. In Fig. 37, the overlapping parts of a lock seam 163 to be welded are out of direct contact with conductive bars 160, 161 which are connected by a tie bar 162 to a high frequency source and by a tie bar to a proximity conductor, not shown. The metal may be held in place by a permanent magnet 167. In Fig. 40, a conductive anvil 177 and proximity conductor 185 are hinged together. In Fig. 41, a metal strip 195 is placed on a support 196 having a recess 197 and the current is passed through a pair of conductive bars 190, 191 and proximity conductor 7, and a similar arrangement is used (Fig. 44, not shown) for making butt join. In Fig. 61, a metal tube is held between conductive clamps 284 and 285 which apply the forging pressure at the appropriate temperature.