GB297493A - Process of and apparatus for welding - Google Patents

Abstract

297,493. Beatty, W. E., (Bell Telephone Laboratories, Inc.). June 23, 1927. Controlling consuming devices.-In a process of welding copper wires, rods, &c. the abutting surfaces of the parts are electrically heated to a temperature higher than the welding temperature, are then cooled to welding temperature and are then percussively engaged with each other. The welding circuit contains either a number of nickel wires or a variable inductance to vary the heating effect. The copper rods &c. 9, 10 are secured with wedge-shaped ends abutting at right angles in a fixed and a movable pair of jaws 7, 8, respectively. The jaws are connected to the terminals of the secondary 34 of a transformer. In the conductor between the jaw 8 and the transformer are located in parallel a number of nickel wires 36 which, when cold, allow a large flow of current, but which, on account of their high temperature coefficient of resistance, limit the current as the temperature increases. The welding switch 37 is closed against the action of a spring 38 by the relay 36 of a control circuit provided with switches 39, 41. The inner sides of the jaws, 7, 8 are made parallel so as to form together the work a single turn of a coil, the effect of which, when the current is switched on, is to cause the jaws to separate magnetically and serve as a magnetic blow-out. On withdrawing a pin 48 the switch 39 is closed so as to complete the welding circuit, and a weight 46 is released. The ends of the rods are immediately fused and the molten parts are removed from the joint by the magnetic blow-out. An account of the inertia of the weight 12, a gap remains between the ends of the work. The current is automatically reduced by the nickel wires so that the work begins to cool and at a predetermined period of movement of the jaw 8 a screw stop 43 thereon opens the switch 41 and thus cuts out the current to allow the parts to cool to welding temperature. In a modification, the nickel wires are replaced by a variable inductance 64, Fig. 4, consisting of a yoke 65, a coil 67 of a few heavy turns wound on a non-magnetic tube and a movable core 68 so that the initial current is large so as to heat the parts and is reduced so as to allow the parts to cool to welding temperature as the core, which has considerable inertia, is drawn forward against the action of a spring 69'. Specification 271,431 is referred to. The control circuit is completed by a push button switch 39.