GB874423A - Improvements in or relating to electric resistance heating and forming of metal articles - Google Patents

Abstract

874,423. Casting composite articles; making sheets; welding by pressure; brazing; extruding; jointing by forging. UNITED KING- DOM ATOMIC ENERGY AUTHORITY. March 5, 1959 [March 14, 1958], No. 8211/58. Classes 83 (1), 83 (2) and 83 (4). At least one metal sheet is compressed between resistance heating electrodes, at least one of which has a cavity on its face, the depth of the cavity being greater than its width, the metal of the sheet in the zone compressed by the electrodes being at least partially fused by the passage of the electric current and injected into the cavity to form a projection. The sheet 10, Fig. 1, in contact with the cavitied electrode 12 is perforated and the two sheets 10, 11 are fused together. Alternatively the two sheets may be of materials which do not weld with each other or are surface-treated to prevent welding so that after the formation of the projection 17 the sheet 11 may be removed. Inserts such as a copper peg 22, Fig. 2, springs, non-metallic inserts such as an alumina peg may be held in the electrode cavity for incorporation in the projection, and the projections may be drilled and wires, rods, thermocouple cables, &c. secured therein by brazing. In a further modification, Fig. 3, sheets 27, 28, 29 of titanium and 26 of magnesium are compressed between the electrodes, and a projection 35 formed while simultaneously the magnesium sheet forms a hooked projection 33 which is secured in the fused area of the titanium sheets. Projections may be formed on both sides by forming a cavity in each electrode. Heat-exchange elements may be made by forming projections of aerofoil section, and hollow panel sections may be made by forming projections on a sheet and resistance welding a sheet to the projections. A split electrode may be used to form projections of shapes which cannot be withdrawn directly from the cavity.