Patent GB-1067719-A (GB)
Title: Drill pointing machine
IPC: B24B3/26
Filed: 1964-08-12
Abstract: 1,067,719. Grinding drills; chucks; drills. WINSLOW PRODUCT ENGINEERING CORPORATION. Aug. 12, 1964 [Aug. 19, 1963], No. 32876/64. Headings B3B, B3C and B3D. A drill pointing machine comprises a frame 32, Figs. 1 and 3, a drill support 52 including a shaft 76 and a drill holder 54 on one end of the shaft for positioning a drill to be pointed with the drill axis 242 laterally offset from and extending transversely of the axis 58 of the shaft, and means 80 mounting said shaft on said frame for oscillation of the drill support about and reciprocation along the shaft axis 58, a motor 84 carried directly by the shaft, and means on the shaft driven by the motor and coacting between the frame and drill support for oscillating and reciprocating the latter in timed relation on the shaft axis. The shaft 76 is mounted in a sleeve bearing 80 in the frame 32 and is secured at its lower end to a housing 82 and at its upper end to the drill holder housing 52. The motor 84 is secured to the lower housing and drives a shaft 86 which passes through the hollow interior of the shaft 76 and is connected by bevel gears 288, 286 in a housing 52 and gears 280, 276 to a worm shaft 272 engaging a worm-wheel 270 on the drill holder. The shaft 86 has a worm 88 at its lower end engaging a wheel 90 on a shaft carrying three cams 96, 98, 100, Fig. 5. The cam 96 co-operates with a follower 102 on an arm 104 carried by a shaft 106 rotatably mounted on the housing 82 and engaging a rod 112 which passes through the shaft 76. The upper end of the rod is spherical and engages a hardened ring 222, Fig. 12, on one side of a sleeve 186 rotatably mounted in the housing 52 coaxial with a shaft 282 carrying the bevel gear 286. A plate 232, Fig. 3, is secured to the end 194 of the sleeve 186 and carries the drill holder 54 such that when the cam 96 is rotated, the sleeve 186 oscillates to rock the drill about an axis 214 perpendicular to its longitudinal axis 242. The rocking motion is effected against the action of a spring and is used during the grinding of a conical drill point. The sleeve can be locked in a position out of engagement with the end of the rod 112 by a locking lever 226 whereby the operation of the cam 96 is ineffective during grinding of a helical drill point. The cam 98 acts to oscillate the shaft 76 and drill holder about the axis 58 and cooperates with a follower 114, Fig. 5, on a bellcrank lever 118 mounted on a pivot 120 on the housing 82. One arm of the lever 118 engages a fulcrum 130 to cause oscillation of the shaft 76 against the action of a spring 148. The position of the fulcrum is adjustable by a control knob 44 connected by gearing to a rack 128 carrying the fulcrum. The cam 100 acts to reciprocate the shaft 76 and co-operates with a follower 150 on a lever 152 engaging a fulcrum 172 on a cranked plate 164 pivotally mounted on the frame 32. The position of the fulcrum is adjustable by a control knob 42 connected to a rack 158 movable on the plate 164 and carrying the fulcrum 172 to adjust the stroke of the shaft 76, and the initial position of the shaft is adjustable by a control knob 40 connected to a screw 180 abutting the plate 164. The drill holder 54, Fig. 3, is adjustably mounted on the plate 192 so that, when the lever 226 is engaged to prevent rocking of the drill holder, the angle of the axis 242 of the drill can be adjusted about the axis 214. The drill holder consists of a housing 230, Fig. 8, which rotatably supports a collet holder 250 to which is secured the worm-wheel 220 driven by the worm 272 from the motor shaft 86. The holder slidably receives a collet 74 which is provided with a pin 268 for engagement with a notch 266 on the holder to locate the collet therein. A sleeve 290 is slidable in the body 260 of the collet and has a tapered bore 298 engaged by a plurality of radially extending blades 304, Fig. 10, held in spaced apart relationship by a resilient mouldable material 302, the inner ends of the blades forming a bore for gripping a drill D when a spring 294 acts to press the sleeve 290 forwardly. A plate 62 is mounted on the drill holder and carries a plurality of different sized bushes 312 for accurately supporting a drill gripped in the collet. A device 72, Fig. 1, for accurately locating the drill both axially and angularly in the collet is mounted on the frame of the machine. The collet 74 can be removed from the drill holder 54 and positioned in a seat 324 with the join 268 engaging a slot 268a. The collet is formed with a pair of openings 330, Fig. 8, to enable pins 334 on a pivoted yoke 326, Fig. 1a, to engage a circular groove 32 in the sleeve 290. The yoke can be rocked by a handle 328 rotating a cam 329a engaging a follower 329d to move the sleeve against the spring 294 so that a drill can be withdrawn and inserted in the collet. At the same time, the handle 328 rotates a cam 329b engaging a follower on a lever 337 carrying a disc having a number of locators 338, a selected one of which is aligned with the drill to be ground, the movement of the lever causing the locator to engage and angularly and axially position the drill before the yoke permits the collet to grip the drill, the collet then being removed from the device 72 and positioned in the holder. The grinding wheel is rotatably mounted in a bearing 344 which, with the motor 356 driving the grinding wheel is mounted on a carriage adjustable by a screw-and-nut mechanism towards and away from the drill holder. The grinding wheel is shaped with an operative portion S, Fig. 18, and an edge E which has a small radius for helical sharpening and a larger radius for conical sharpening. The profile of the grinding wheel is formed by a dressing tool 382, Fig. 16, carried intermediate a lever 364 which at one end is mounted for pivotal movement about horizontal and vertical axes 320, 372, and at the other end has a follower 384 engaging a cam 386. The cam can be adjusted to present one or other of contours 386a, 386b to the follower according to the type of drill pointing to be effected. To grind a helical drill point, the grinding wheel is first trued by the dressing tool under the control of the follower engaging the portion of the cam 386 which produces the edge E having the small radius. The drill to be sharpened is then positioned by the device 72 in the collet 74 and the collet inserted in the drill holder. The lever 226 is engaged to prevent the cam 96 and rod 86 from rocking the drill holder about the axis 214 and the holder adjusted about that axis on the plate 192 to position the axis 242 at an angle which will produce the desired tip angle on the drill. When the motor 84 is rotated, the cams 98 and 100 reciprocate and oscillate the shaft 76 so that, as the drill is rotated by the drive from the shaft 88, gears 288, 286 and worm and wheel 270, 272, the drill is advanced substantially axially and laterally upwards across the surface S and edge of the grinding wheel to grind one face and is then retracted and the sequence repeated for the second cutting face. All radial lines on the cutting faces are at the same angle, i.e. the tip angle, and the cutting faces are therefore generally helical, the drill tip being slightly undercut. To grind a conical drill point, the grinding wheel is trued by the dressing tool under the control of the follower engaging the portion of the cam 386 which produces the edge E having a larger radius and the lever 226 is retracted to enable the sleeve 186 to be spring urged against the upper end of the rod 86. When the motor 84 rotates the cams 96, 98, 100 and the drill, the latter, in addition to the movements for helical point grinding referred to in the preceding paragraph, is rocked about the axis 214 perpendicular to its longitudinal axis 242 so that all radial lines on the cutting face intersect the drill axis at substantially a common point and the cutting faces are therefore generally conical.