| 摘要 |
1,137,115. Welding by pressure. WELDING INSTITUTE. 12 July, 1967 [18 July, 1966], No. 32187/66. Heading B3R. In friction welding wherein two workpieces are relatively rotated under axial pressure a signal representative of the load on a transmission responsible for the relative rotation is used to control the axial force, in a sense such that for peak levels of the signal the axial force is less than it would be in the absence of such control, at least for the initial portion of the frictional heating cycle. A motor 1 rotates a first workpiece 2 in a chuck 3 and the second, non-rotating'workpiece 4 in a chuck 5 is pressed against the workpiece 2 by a piston 6 in an hydraulic cylinder 7. A torque meter 8 is connected to the stationary shaft and applies a torque signal to an amplifier 9 which receives a command signal from a preset device 10. The output of the amplifier, the difference between the torque and command signals, is applied to a further amplifier 11 whose output is applied to a solenoid in a servo valve 12 which acts through the direction selector valve 14 to control the pressure at port 13 in cylinder 7. The force level is controlled by adjusting the leakage from the supply line 15 through the servo valve. If the torque signal equals the control signal the valve is in a neutral balanced position to provide a controlled leakage. With no load on the transmission the servo valve is closed and as the load increases to and above the command level the leakage will be increased. The servo valve may be connected to control fluid flow at both ends of the cylinder. The control of the axial force is preferably continued for the major part of the heating cycle but is discontinued when upset pressure is applied during deceleration of the workpieces. The duration of the controlled period may be defined by a pressure switch or displacement switch and the final arrest of the rotating workpiece and application of upset pressure may be controlled by an automatic timer. If hydrostatic transmission is employed a pressure transducer instead of a torque meter is employed. |
