Patent GB-968235-A (GB)
Title: New or improved indexing mechanism
Inventor: WADE RAYMOND
IPC: B23Q16/06
Filed: 1962-02-01
Abstract: 968,235. Grinding; machine tool details. DAVID BROWN INDUSTRIES Ltd. Feb. 7, 1963 [Feb. 11, 1962], No. 3787/62. Headings B3B and B3D. An indexing mechanism for a grinding machine for sharpening hobs comprises an hydraulically-operated device 38, Figs. 3 and 4, for imparting intermittent angular movement to a spindle 15, locking means 56 operative to retain the spindle in each of its angularly adjusted positions, and means 33 for allowing the device to move in a reverse direction after operation of the locking means. The hydraulically-operated device consists of a piston 38 which is slidable in a cylinder 39 and formed with a rack 40 engaging a pinion 32 releasably restrained from rotation relative to the spindle 15 by a friction clutch having a member 35 urged into contact with a friction surface 33 on the pinion by a spring 36. The spindle 15 is rotatably mounted in bearings in a housing 27 and, at one end, has a socket 16 for receiving a holder for the hob to be sharpened, and at the other end replaceably carries a dividing plate 29 and a blanking plate 30. The plates are formed with notches which are selectively engaged by a plunger 55 urged towards the plates by a spring 61 and formed with a tapered hole 58 engaged by a wedge-shaped member 60 carried by a piston 51 in a cylinder 53. A screw 42 is disposed beneath the piston 38 and has a stop 46 which is adjustable along the screw so as to be engaged by a member 47 slidable on the screw and engaged in a recess 48 in the piston 38. The stop is adjusted so that movement of the piston rotates the spindle 15 slightly further than the required indexing movement. In operation, when a slide carrying a hob to be sharpened is in one of its extreme positions, a solenoid-operated valve 20, Fig. 6, is moved to connect a pump 69 to a line 75 leading to the cylinder 53 so that the piston 51 causes the wedge-shaped member 60 to raise the plunger 55, the movement of which actuates a switch preventing movement of the slide until the plunger is lowered. When the piston 51 reaches the end of its stroke, the rise in pressure in line 25 actuates a sequence valve 80 so that fluid can flow through line 29 to move the piston 38 a distance determined by stop 46 slightly greater than the required indexing movement, the piston actuating a switch 66 serving the same function as that actuated by the plunger. When piston 38 reaches the end of its stroke, the rise in pressure actuates a switch 81 to de-energize the solenoid of valve 70 and connect the fluid supply to line 76 to return piston 51 and withdraw member 60 so that the plunger 55 engages the periphery of the plates. On completion of the return stroke of piston 51, the rise in pressure in line 76 actuates a sequence switch 83 to connect the supply to a line 82 and return piston 38 to its initial position. During the first part of the movement of piston 38, the spindle is rotated until the plunger 55 engages the selected notch in plates 29, 30, the friction clutch 33, 35 then permitting the piston 38 and pinion 32 to return to their initial positions without rotation of the spindle. When both pistons 38, 51 have returned to their initial positions, the switches 64, 65 are actuated to permit the slide of the machine to be reciprocated. The plunger 55 has a knob 59 by which the plunger can be withdrawn manually from the notches in the plates. The spindle 15 may be oscillated during reciprocation of the slide 12, Fig. 1, carrying the dividing headstock 11 and a tailstock 17 past an angularly adjustable grinding wheel 13 by vertical movement of a rack 25, Fig. 5, which engages a pinion 26 on the spindle and has a pair of rollers 24 embracing a sine bar 23 angularly adjustable by a worm-and-wheel mechanism 21, 22 operated by a hand wheel 19. In alternative embodiments, the piston 38, cylinder 39 and pinion 32 are replaced by an hydraulic device acting directly on the spindle, and the locking plunger may be operated mechanically or by a solenoid.