GB1456461A - Friction welding machine - Google Patents

Abstract

1456461 Welding by pressure CLARKE CHAPMAN Ltd 23 June 1975 [27 June 1974] 28479/74 Heading B3R A friction welding machine comprises a first member 12 (e.g. a friction welding head slidably mounted on a base 10) movable relative to a reaction member 18 by an hydraulic piston and cylinder device 20 disposed between the first member 12 and the reaction member 18, the piston and cylinder device providing more than one piston-cylinder combination (e.g., as shown in Fig. 2, a piston 260 with spaces 256, 258 and a piston 276 with spaces 272, 274) operated by an hydraulic valve mechanism which selectively renders different piston-cylinder combinations effective. A typical operating sequence comprises securing workpieces in a chuck 26 (driven by an electric motor 28) and a clamp 14 (non-rotatable), the head 12 and the pistons 260, 276 being initially in extreme respective leftward and rightward positions in Fig. 1 and Fig. 2. The head 12 is advanced rapidly by energization of a valve 290 (to a high pressure output setting), of solenoids 236A, 240A, 264A, and of a valve 232 (to provide maximum pressure). Hydraulic fluid is fed rapidly from pumps 212, 214 via valves 232, 240 to a valve 236. Since the solenoid 236A is energized, fluid flows through the valve 236 to the hydraulic space 258 which moves the smaller piston rapidly leftward and hence through piston-rod 280 (Fig. 2) moves the head 12 rapidly rightward (Fig. 1), spaces 272, 274 being connected through an un-operated valve 250 to allow free leftward movement of the piston 276. The pressure rise which occurs on the workpieces abutting is detected and the apparatus automatically performs the next stage wherein the solenoids 240A, 264A are de-energized and solenoid 250A is energized to allow fluid flow from the pump 212 additionally through the valve 250 to the space 274 and the valve 232 is set firstly to a first pressure, secondly to a second higher welding pressure, and thirdly to increase the pressure suddenly to give a forging load at the time the chuck 26 is rapidly halted by a brake. On weld completion, the head 12 is retracted rapidly by setting the valve 290 to maximum pressure setting and by the energization of solenoids 236B and 264A, with or without energization of the solenoid 240A, so allowing fluid flow into the space 256. In an alternative to the rapid head advance above, energization of the solenoid 264A is omitted and energization of the solenoid 250A replaces that of the solenoid 236A so that slow advance is obtained. The machine may have one piston-cylinder device 20 on each side of the head 12 or the pistons 260, 276 may be secured to different piston-rods. The clamp 14 and backstop 16 may be movable and the head fixed. The workpieces may also be moved in relative orbital movement.