Patent GB-1267056-A (GB)
IPC: B23K20/12
Filed: 1969-06-11
Abstract: 1,267,056. Welding by pressure. NORTH AMERICAN ROCKWELL CORP. 11 June, 1969 [16 Aug., 1968], No. 29620/69. Heading B3R. Apparatus for automatically friction welding first and second workpieces to a third workpiece includes mounting means for holding the third workpiece stationary, rotatable means for gripping and rotating the first and second workpieces, force application means operatively connected to the rotatable means to move the first and second workpieces into contact with the third workpiece and control circuit means to control operation of the rotatable means and force application means and selectively actuatable in a sequential or simultaneous automatic welding operation to sequentially weld the first and second workpieces to the third workpiece or to simultaneously weld the first and second workpieces to the third workpiece. In friction welding three workpieces end to end the central workpiece 12, e.g. an axle housing centre section is held stationary in a cradle 14 on a machine base by adjustable jaws 15, 16 and 18, 19 and workpieces 11, 13, e.g. wheel bearing and spindles are mounted upon similar hydrostatic bearing carriers 22, 23 respectively at opposite ends of the workpiece 12. The jaws 15, 16 are driven by an hydraulic piston and cylinder device and the jaws 18, 19 are driven by rotary hydraulic motors. The carrier 22 comprises an annular frame 51 having side members slidable on rails 52, 53 on the machine base, hydraulic cylinders 53, 54 being fixed to the base with their piston-rods 56, 57 secured to the side members to effect movement of the carrier along the machine base. Shaft 58 extends slidably with a splined connection through an axially stationary pulley 61, the pulley being driven by belts 63, 64 from a drive motor 67 having braking devices 47, 68, and the shafts being operatively connected to the workpiece 13 in the carrier. The carrier 23 is similarly mounted to slide along the machine base with a similar drive shaft connection. A housing T1, Fig. 3, is fitted within the frame 51 of carrier 22 and a frusto-conical nose portion 75 is secured to the housing, the housing having a large recess 77 with front and rear spaced cylindrical surfaces 78, 79. Within the recess 77 is secured a core section 83 having cylindrical surfaces 85, 86 mating with and sealed to surfaces 78, 79 so that an annular chamber 89 is formed within the housing. The driven shaft 58 is connected to the end of a drive sleeve 92 splined to a hollow arbor 95 having a surface 97 within a bore 98 in the core 83, a radially enlarged flange 99 adjacent a flat face 100 of the core 83 and a front section 101 within the nose portion 75. A piston 107 is slidable within the arbor 95, a spring 112 urging the piston to the right in Fig. 3, the piston-rod 114 of the piston carrying a coupling 118 with a series of duct elements 121 to grip the workpiece 11. Heated oil under pressure is supplied through passage 153 to flow through calibrated orifices 157 into a series of circumferentially spaced cavities 154 between the arbor and the nose portion 75 to support the arbor front section 101 on the oil as a hydrostatic journal bearing. Oil is also supplied through passage 161 to the chamber 89 to be supplied to a series of spaced cavities 163 between the arbor and the core 83, to support the arbor rear section on the oil as a second hydrostatic journal bearing. Oil from the chamber 89 also flows into the arbor to force, when the oil pressure is increased, the piston 107 to the left to clamp the workpiece. Oil is also supplied by a passage 181 to the space between the rear face of the arbor flange 99 and the front face 100 of the core 83 to flow to a low pressure passage 162, the oil providing a first hydrostatic thrust bearing. Oil from the front of the piston 107 flows through radial passages 191 in the flange to a groove 194 to form a second hydrostatic bearing. The carrier 23 has similar hydrostatic journal and thrust bearings. Two separate hydraulic circuits are provided for the hydrostatic bearing units and circuit means for jogging the carriers individually are included in the control circuitry for the apparatus. Two interlocked press button switches are included which are pressed to open one and close the other to arrange the circuit to effect simultaneous welding of the workpieces 11, 13 to centre workpiece 12. In operation energization of the drive motor for rotating the workpiece 13 is prevented and the carriers are accelerated towards the centre workpiece 12 with only the workpiece 11 rotating, the carriers are then decelerated so that rotating workpiece 11 and non-rotating workpieces 13 are abutted gently against the workpiece 12, pressure between the workpieces is abruptly increased and then allowed to build up to a higher level and then with the brakes applied the rotating workpiece 11 stops. Carrier 23 is then returned but the carrier 22 remains in position and with rotation of the motor coupled to workpiece 11 prevented and rotation of the motor coupled to workpiece 13 effected the carrier 23 is advanced as before to weld workpieces 13 and 12. The final welded workpieces 11, 12, 13 are then removed from the machine. To effect simultaneous welding of workpieces 11 and 13 to workpiece 12 the aforesaid button is pressed to close the one and open the other switches and with both workpieces 11, 13 rotating the carriages are moved forward as before. The control of the operations are by means of timers. A modified prior art circuitry adapted only for simultaneous welding of the workpieces is also described.