GB1254889A - Forming method - Google Patents

Abstract

1,254,889. Welding by pressure; electromagnetic forming. INDUSTRIAL MAGNETICS Inc. 14 March, 1969 [1 April, 1968], No. 13650/69. Headings B3Q and B3R. In a forming method, members are placed in contact with each other and if the members are not conductive conductors attached to the members are placed in contact with each other, an induction coil is placed adjacent the members and a forming current is passed through the coil to induce in the members, if conductive, or in the conductors, currents flowing in the same direction parallel to each other and to the interface between the members, the currents causing the members if conductive or the conductors to be forced towards each other to effect forming of the members. Two stainless steel pipes 11, 12 are abutted at interface 13 and are tightly surrounded by a stainless steel sleeve 14 which defines interfaces 15, 17 with the pipes. An induction coil assembly 10 is arranged about the pipe and sleeve and comprises an outside sleeve 20 of P.T.F.E., end plates 22, 24 and an inner sleeve 26 of ceramic aluminium silicon magnesium and within the space defined by these plates and sleeves a two-turn hollow copper coil 28 embedded in epoxy resin. Each turn of the coil 28 surrounds a copper ring 30 and the ends of the coil 27, 29 extend out through the sleeve 20 for connection to cooling water and current. Pipes 41 supply argon to passages 40, 44 in the assembly 10 for supply to the gap 46 between the assembly 10 and the workpieces. In operation a high frequency current of 10<SP>4</SP> Hertz is supplied from a motor generator circuit to the coil 28 to heat the workpieces inductively and then the motor generator circuit is disconnected and a charged capacitor bank is connected to the coil to induce currents in the pipe and sleeve which draw the pipe axially together and the pipe and sleeve together. A second cycle of heating and pressure applicator may be applied and argon is supplied during the process.