Patent GB-959873-A (GB)
Title: Improvements in grinding machines
IPC: B24B47/04
Filed: 1962-11-07
Abstract: 959,873. Grinding. MICHIGAN TOOL CO. Nov. 7, 1962 [Jan. 10, 1962], No. 42115/62. Heading B3D. A grinding machine comprises an axiallymovable shaft 28, Fig. 4, adapted to support a workpiece 34, such as a ball-bearing retaining cage of a universal joint, a grinding wheel spindle 56, Fig. 3, mounted for movement towards and away from the shaft, a dresser support 69 mounted for axial movement with the shaft, means for continuously oscillating the shaft about its axis, stationary means 75 for holding the dresser support against rotation during oscillating movement of the shaft, means for axially moving the shaft, and means for moving the spindle towards and away from the shaft axis. As described, the machine has six grinding wheel spindles 56 which are mounted in slides 51 and interconnected by bell-crank levers 63 and links 66 so as to be movable towards and away from the workpiece by a motor 58. The workpiece, which is to have the surfaces 38, 39, Fig. 1, of apertures 37 ground, is held on a workpiece support 32 by a clamp 42 connected by a rod 45 to a piston 48 in a cylinder supplied with fluid pressure through a passage 49 in the shaft 28, the support being secured to the shaft. The shaft is axially movable in a sleeve 25 rotatably mounted in the frame of the machine, rotation between the shaft and sleeve being prevented by a key 29 engaging a keyway 31. The dresser support 69 is rotatably mounted on the shaft 28 but prevented from rotating relative to the frame 22 by a key 75 engaging a keyway 73. The lower end of the sleeve 25 and key 29 are connected by a clevis 79, Fig. 6, to a lever 81 joined by a shaft 78 to an eccentric 77 rotated by a fluid motor 76 whereby the shaft 28 and workpiece are oscillated. The shaft 28 is vertically movably by an eccentric 86 rotatably mounted in a member connected by a pivot 92 to an adaptor 88 rotatably mounted on the lower end of the shaft 28. The eccentric 86 is formed on a shaft 82 on which is secured a cam 96 having lobes 98, 99, the cam being connected to a fluid motor 105 and being engaged by a roller 102 mounted in a slide 103 movable in guides 104 by a screw 112 rotatable by a pawl-and-ratchet mechanism 121, 118, the pawl being movable by a fluid motor, or by a hand wheel 129. The screw 112 is rotatably mounted in a support 117 on a grinding feed slide 115 movable by a fluid motor 132 connected to the slide by a link 138. In operation, the diamond dressers 67 are aligned with the desired finished position 38<SP>1</SP> of the surfaces 38 and the workpiece moved to an initial position by fluid pressure supplied to the head end of motor 132 moving slide 115 into engagement with an adjustable stop 145, fluid pressure also being supplied to the head end of motor 105 to swing the cam 96 counterclockwise so that lobe 98 engages the retracted roller 102, the swinging of the cam rotating the eccentric 86 to move the axially shaft 28 and workpiece. At the same time, motor 76 is energized to effect the continuous oscillation of the shaft. The grinding wheels 52 are moved towards the workpiece by pressurization of motor 58 and the motor actuating the pawl 121 is operated to rotate the ratchet and lead screw 112 to further retract the roller 102, motor 105 causing the cam to rotate a slight distance further counterclockwise until it engages the roller so as to move the shaft upwardly a dressing feed distance before the grinding wheels pass the dressers. After dressing, the supply to motor 132 is reversed to rock the cam against the pressure in motor 105, the workpiece thus being lowered to permit entry of the grinding wheels into the apertures of the workpiece. Pressure is then supplied to the head end of the motor 132 after the leading ends of the grinding wheels have passed the inner edges of surfaces 38 to again retract roller 102, cam 96 again rotating so that the shaft 28 is moved upwardly feeding the oscillating surfaces 38 of the workpiece against the grinding wheels while the latter continue to move inwardly. At the end of the inward stroke, the motor 132 is retracted to cause clockwise movement of the cam and return the workpiece to its initial position. Thereafter the pressure is reversed in motor 105 to bring the lobe 99 of cam 96 into engagement with the roller 102, and the pressure reversed in motor 58 to cause the grinding wheels 52 to move radially outwardly from the workpiece. Fluid is also supplied to the head end of motor 132 to cause roller 102 to be withdrawn from cam 96, the lobe 99 being maintained in engagement with roller 102 so that the slide 115 engages stop 145, the shaft 28 and workpiece being positioned so that the oscillating surfaces 39 are ground during the outward movement of the grinding wheels.