GB1187970A - Improvements relating to Methods of and Apparatus for Friction Welding. - Google Patents

Abstract

1,187,970. Welding by pressure. JOHN THOMPSON ORDNANCE CO. Ltd. 18 Dec., 1967 [16 Dec., 1966; 16 Feb., 1967], Nos. 56405/66 and 7377/67. Heading B3R. In friction welding, relative rotation is effected between the workpieces by engaging the exterior surface of a workpiece of circular cross-section directly with an exterior curved surface of a rotary driving member of circular cross-section, the exterior curved surface of the driving member having a diameter at least twice that of the engaged workpiece. A baseplate 11 supports an end plate 12 at one end and a pair of upstanding posts 13 at the other, a pair of horizontal laterally spaced guide bars 14 being supported between the plate 12 and posts 13. On the bars 14 are mounted two end workpiece supports 20a, 20b and a central workpiece support 40, the former supporting two end portions of wire from coils and the latter supporting an insert length of wire. The support 20a comprises a bridge like body part 21a, Fig. 2, through which passes the bars 14 and which carries a rest 24a affording a channel 25a for a wire end 25. A clamping plate 26, the lower surface of which is planar as shown or V grooved, is adjustably mounted on an arm 29a pivoted between trunnions 31a on the bridge support, the arm 29a being movable by a piston and cylinder 35a. The support 20a has legs 38 screwed to the base 11 and the other support 20b is similar but has no legs 38 being slidable on the bars 14 by a piston and cylinder unit 65, Fig. 5, secured between the end plate 12 and the bridge of the support. The central support 40 has a body part 41, Fig. 3, slidable on the guide bars 14, the body part having upwardly extending trunnions 44 between which a pair of roller elements 45 are journalled about horizontal axes. Each element 45 comprises a pair of axially spaced rollers 46 and between them a gear 47, the rollers 46 forming a central channel 54 for the insert wire. A roller 50 is supported above the channel 54 in a forked arm 49 pivoted between trunnions 52 on the body 41 and movable by a piston and cylinder 60. A motor 76 drives through a belt 81 a drive shaft which is connected by a coupling 90, Fig. 5, to a driven shaft 82, Fig. 2, carrying a pinion 85, Fig. 3, meshing with a freely rotatable gear 86 in turn meshing with the gears 47 of the two rollers 45. The coupling 90 comprises radial arms 92 on the drive shaft, radial arms 98 on the driven shaft at 90 degrees to the arms 92 and two bars 101 extending between pins on the arms with universal joint connections which permit substantially frictionless relative axial movement of the shafts. In operation the ends of wires from coils are clamped in the channels in the end members 20a, 20b, an insert length of wire is pressed down on to the rollers 45 by the roller 50 and the rollers 45 are driven by the motor 76. The piston-cylinder 65 presses the part together with a low pressure, e.g. 1 ton p.s.i. until the contacting faces are heated to red heat in say 5 sees., the pressure is then increased possibly in a linear manner to 5 ton p.s.i. the rollers 45 are stopped by applying a disc brake included in motor 76 and the pressure is still further increased to say 10 ton p.s.i. to effect welding. Mild or high carbon steel wires may be welded and the rate of cooling should avoid a brittle martensitic structure. The contacting faces may therefore be brought to welding temperature slowing so that a small temperature gradient exists. Electronic timers control the time of application of the various pressures and stopping of the motor. Two workpieces only may be welded in a similar apparatus but having only one fixed support and one movable support the fixed support including the roller drive means. Similar apparatus may be used for welding workpieces other than wires, e.g. a propeller shaft having forked coupling members at each end with the forks at one end at an angle to the forks at the other. For welding very small workpieces, e.g. 0À15 inch diameter the central support is modified by employing large idle or driven backing rollers at the sides of the work supporting rollers and a larger driven roller beneath the work supporting rollers. The work supporting rollers are driven by the driven backing roller or rollers. Alternatively the work is driven by a separate short driven roller beneath the work.