Patent GB-1011655-A (GB)
Title: Improvements in or relating to grinding machines
IPC: B24B19/04
Filed: 1964-05-26
Abstract: 1,011,655. Grinding. O. GUHRING, A. GUHRING, and M. GUHRING, [trading as GOTTLIEB GUHRING]. May 26, 1964 [June 14, 1963], No. 21807/64. Heading B3D. A machine for grinding the flutes and relief of twist drills 10, 11, Fig. 1, comprises a wheel 18 for grinding a tapered flute so that the drill has a tapered core, a wheel 14<SP>1</SP> for grinding the relief on a drill, and a turret 7 which is mounted on a spindle 5 and has at least two workpiece spindles 8, 9, each of which is successively used in the grinding of the flutes and the grinding of the relief whereby both grinding operations are carried out at the same time. The turret 7 is carried by a quill 5<SP>1</SP> rotatably mounted on the spindle 5 which is in two parts separated by a differential gear 4 or a rotary piston and cylinder and rotatably supported in a headstock 3 movable along a guideway 2 on the machine base 1 by a landscrew 6. An indexing mechanism T is mounted in the headstock for rotating the turret through 180 degrees steps when the turret has two workpiece spindles 8, 9 successively presented to the grinding wheels, or 120 degrees steps when the turret includes a third workpiece spindle and the spindles are successively presented to the grinding wheels and a loading and unloading position. The wheel 14<SP>1</SP> for grinding the relief on the drills is mounted on the spindle 14 of a vertically adjustable carriage 13. The wheel 18 for grinding the flutes is secured to a spindle 17 in an eccentric sleeve 19 mounted on a carriage 15 which is vertically adjustable on a guide 16 and set at an angle corresponding to the twist to be formed on the drill. The eccentric sleeve 19 has an arm 20 connected by a cable 21 to a follower 23 engaging a cam 24 carried by the headstock and having gears 25 to adjust its inclination. In operation, the workpiece spindles 8, 9 are rotated by gearing 12 from the spindle 5 as the headstock is advanced by the screw 6. The movement of the headstock causes the cam 24 to displace the follower 23 and, by means of the cable 21, rotate the sleeve 19 so that the wheel 18 is gradually raised to grind a tapered flute on the drill carried by the spindle 8; at the same time the wheel 14<SP>1</SP>, which does not move vertically, grinds the relief on the drill carried by spindle 9. After retraction of the headstock, the drills are indexed through 180 degrees by the differential gearing 4 or rotary piston and cylinder and the cycle is repeated for grinding the second flutes of the drills. Thereafter, the turret is indexed to reverse the positions of the drills. The cable 21 incorporates an hydraulic control unit 22 for effecting rapid withdrawal of the grinding wheel 18. A mechanical linkage may be incorporated in the cable 21 and the cam 24 may be replaced by a cam rotated by a rack on the headstock. In other embodiments, the side 15 is moved by a cam on the headstock directly acting on the slide or by a lead screw driven by an electric or hydraulic motor controlled by a cam on the headstock.  The indexing mechanism T consists of a piston 45, Figs. 10 and 11, which is automatically movable in the headstock by hydraulic fluid and is formed with a rack 46 engaging a pinion 47 secured to a hub 48 rotatable on the quill 5<SP>1</SP> and integral with a cam wheel 49. An indexing plate having two or three notches 51, according to whether the turret carried by the quill is to be moved through 120 degrees or 180 degrees steps, is secured to the quill. A detent tooth 53 is urged by a spring 54 into engagement with an aligned notch on the plate and carries a pivot 55 for a finger 56 urged by a spring 57 against a pin 58. When the turret is to be indexed, the piston 45 is moved to the right rotating the pinion 47 and cam wheel counter-clockwise so that a cam portion 60 engages the finger 56 to raise the detent tooth 53 from the notch 51 in the index plate. The further rotation of the cam wheel then causes a spring-pressed pawl 59 to engage a notch on the index plate which is then rotated. Shortly before the reset notch is aligned with the finger, the finger 56 drops into a portion 61 to permit the finger 53 to engage the notch 51 when aligned therewith. During the return movement of the piston 45, pinion 47 and cam wheel 49, the finger moves about its pivot 55 against its spring without lifting the detent tooth from the notch.