Patent GB-1382234-A (GB)
Title: Friction welding
IPC: B23K20/12
Filed: 1970-12-16
Abstract: 1382234 Welding by pressure MITSUBISHI JIDOSHA KOGYO KK 15 March 1972 [16 Dec 1970] 59813/70 Heading B3R A method of friction welding together two coaxial workpiece bodies in a correct relative rotational position comprises the following successive steps; (1) axially pressing the bodies against each other with a predetermined pressure while relatively rotating said bodies, to frictionally melt their contacting surfaces; (2) discontinuing the relative rotation and bringing it to zero while maintaining said pressure; (3) sensing whether the bodies are in the correct relative rotational position and, if necessary, correcting by quickly relatively rotating said bodies, to achieve said relative rotational position; and (4) upsetting the bodies by axially pressing them against each other with a pressure which is equal to or larger than that in step (1). Said correcting rotation may be achieved by an hydraulic device acting through a rack-andpinion, by an electric motor, or, as shown, by facial cam means. As shown, a workpiece body 3 is held in an axially fixed chuck 4 rotatable by a prime mover 7 through a clutch and brake 5. A workpiece body 10 is held in a non-rotatable chuck 11 axially slidable in a cam sleeve 14 in turn axially slidable in a housing 1. The cam sleeve 14 co-operates with a further cam sleeve 13 fast with the chuck 4. The sleeves 13, 14 have facial cam teeth 13a, 14a which effect relative corrective workpiece body rotation when the sleeve 14 is upwardly moved by pressure in a cylinder 15. The chuck 11 is acted on, to press the workpiece bodies together, by pressure in a cylinder 12. In operation, the body 3 is rotated and axial pressure P 1  is applied to the body 10 for a time t 1  to frictionally melt the contact areas; the clutch is disconnected and the brake applied to station the body 3 in a time t 2 ; the brake is released; the cam sleeve 14 is upwardly moved until the cam teeth 13a, 14a are meshed in a time t 3 , thereby correctly relatively rotationally positioning the bodies; and, finally, an upsetting pressure P 2  is applied to the body 10 for a time t 4 . In Fig. 8 (not shown), a control device (12a) is provided for control of cylinder 12 pressure. The Specification provides several examples of setting and variation of pressure (P 3 ), on the workpieces, during the corrective rotation, between zero and the upset pressure, such as to (1) increase critical correction time (i.e. the maximum permissible time for the correction step if a weld of strength equal to that of the  base metal of the workpieces is to be achieved; (2) reduce variation in the amount of the correction upset, and (3) reduce torque required for the corrective rotation step. The cam teeth 13a, 14a may be provided as single teeth, in pairs as shown (for 180 degree mating) or in any numbers, and may be sloped one way only for one-way corrective rotation or (as shown) two ways for two-way corrective rotation. To reduce impact on these teeth, the teeth, e.g. 13, may comprise leading protrusions 13a<SP>1</SP>; multiple teeth may be provided, staggered, on nested sleeves (Figs. 16, 17, not shown); or the sleeve 14 may be axially acted on by a sleeve 16 (Fig. 19), a wedge-shaped protrusion and a notch 17, 18 provided respectively on the sleeves 14, 16 or 16, 14, acting to transfer the correcting axial and rotational movement to the cam sleeve.