Patent GB-787880-A (GB)
Title: Improvements in or relating to machine tool feed transmission
IPC: B23B3/10
Filed: 1956-01-17
Abstract: 787,880. Lathes. GIDDINGS & LEWIS MACHINE TOOL CO. Jan. 17, 1956 [Aug. 3, 1955], No. 1557/56. Class 83 (3). [Also in Groups XXIV and XXXVII] A bi-directional overrunning clutch, having a two-gear countershaft connectable in parallel by a second clutch, transmits a drive from a prime mover to a machine-tool element. In a vertical turret lathe a main driving motor 35 drives the work-table 32 through a two-speed epicyclic gear 78 controlled by a lever 79, and provides the feeds for the movable tool rams 42, 43, 45 through the driving shafts 96, 100, 110 and 111 and the respective control heads 58, 62, 51. The heads 58, 62, 51 are similar and each provides sixteen feeds of the respective tool holder in each of eight directions by a rotary feed selector switch 68 and a swivel direction selector switch 69; manual feed is obtained by a handwheel 64, and automatic feed stops in both vertical and horizontal travels by scales and micro dials 65, 66. A traverse motor 150 provides traverse for the cross rail 56 through up and down clutches 176, 177, and for the rams through shafts 152, 162 which provide the traverse independently of the table motion. Feed gearing. Power from the main drive motor 35 is transmitted to the head 62 by shaft 100 and bevel gears 102, 104 to the centre hexagonal member 185a, Fig. 4, of a bi-directional overrun device 185. The device comprises a first hexagonal member 185a, a second member 191 formed as a gear on its periphery and free to overrun in either direction when its speed is greater than that of the first and third members, and a third member 185c having a three-pronged head having slight angular freedom with respect to the hexagon 185a. Rollers 185d are interposed between the opposite corners of the prongs, the alternate flats of the hexagon and the bore of the overrunning member 191. Thus torque will be transmitted between the shaft 190 of the hexagon and the overrunning gear 191 only when the gear 191 is rotating more slowly than the driving hexagon or when the gear 191 is driving and running faster than the hexagon. The prong member 185c is connected to one side of an electromagnetic friction-disc clutch 192, the other side of the clutch being connected to a gear 194 journalled on the shaft 190. The gears 191, 194 mesh with a gear pair 196 such that two speeds are obtainable by engagement or disengagement of the clutch 192. The gears 196a, 196b mesh with gears 205, 204 respectively acting as the overrunning member of a second device 187 and connectible to a second prong member through a clutch 201. This provides a four-speed input to a third clutch 209 and overrun device 189 to provide eight speeds of a shaft 210 by the permuted engagement of the three clutches 192, 201, 209. A countershaft gear 219, 226 and 224, 225 in conjunction with clutches 220, 229 provides a sixteen-speed drive to a gear 230 connected to a shaft 232 through a torque-limiting coupling 230a. From shaft 232 the drive can be transmitted in forward or reverse from gears 238, 239 respectively to the shafts 130 for vertical movement of the ram, and 131 for horizontal movement, by the engagement of the appropriate clutch 242, 246, 275 or 276. The fast traverse drive from bevel gear 156 may be fed through these clutches after engagement of a clutch 286, and hand traverse may be engaged by axial movement of the wheel 64 to engage a gear 291 with either gears 252, 251 or 292, 294. Also geared to the shafts 130, 131 are the indicating dials 65, 66 showing the movement of the ram and providing drive for the automatictrip mechanism. Feed rates election. Any of the sixteen ratesof feed may be selected by a sixteen-position rotary switch 68 (Group XXXVII) which controls the combination of four switches S1, S2, S3 and S4 each having a pair of normally-open and a pair of normally-closed contacts of which only S1.2, S2.1, S2.2, S3.2 and S4.2 are employed to control the clutches 209a, 229a, 220a, 192a, 201a respectively. Feed-direction selection. An eight-position wobble switch 69 (Group XXXVII) controls four switches U.D.I. OT each having a pair of normally closed and a pair of normally open contacts. These four switches may be actuated singly for up, down, in and out motions respectively or may be actuated in adjacent pairs for the four diagonal movements, i.e. up and in, &c. Actuation of switches U1, U2 control the engagement of the clutch 246a, D1, D2 clutch 242a, OT1, OT2 clutch 275a and I1, I2 clutch 276a. A fifth switch T having normally-open contacts T1 and normally - closed contacts T2 is actuated by a push button in the centre of the knob of the switch 69 to release the feed clutches and engage the fast traverse clutch 286a while the switch 69 is in a position to engage any of the direction clutches. Energization of any of the direction clutches energizes solenoids 310 or 311 to provide lubrication to the respective slideways and lead screws of the element caused to move by the respective clutch. Two switches 295, 296 actuated by inward or outward axial movement of the handwheel 64 break the supply to the direction clutches when manual traverse is engaged. Feed - trip mechanism. The dials 65, 66, one revolution of which corresponds to full travel of the ram in the vertical or horizontal direction respectively, are provided with a series of manually-adjustable rings having radiallyprojecting dogs. The dogs actuate switches SP and RP through a roller follower and lever mechanism to break the U.D. and I.OT circuits respectively and thus stop the feed at predetermined positions. Normally-open contacts RP1 and SP1 close at trip to light a warning lamp 500. A switch O actuated by a push-button in the centre of the control dial of the switch 68 overrides the trip switches when feed beyond the trip position is desired.