Patent GB-630068-A (GB)
Title: Improvements relating to automatic turret lathes and like machine tools
IPC: B23B7/12
Filed: 1945-03-28
Abstract: 630,068. Turret lathes. POTTER & JOHNSTON MACHINE CO. March 28, 1945, No. 7889. Convention date, May 26, 1944. [Class 83 (iii)] [Also in Group XXIV] A turret lathe having a spindle, a turret slide, and one or more cross slides, is provided with a driven cam member operatively connected to the turret slide for reciprocating it, and an operative connection between the turret slide and cross slides, whereby the latter are reciprocated from the movement of the former, a cross slide selector mechanism being operable to render the connection effective or ineffective and means on the cam member for actuating the selector mechanism. The lathe comprises a headstock 20, Fig. 1, in which is disposed a work spindle 21 and an automatically - operated variable speed transmission unit, a turret slide 23 and front and rear cross slides 25, 26 respectively ; a feed shaft 30 is driven from the spindle at automatically selected speeds and all idle movements of the tool slides are driven at a constant high speed. The detailed description of the parts of the machine follows under the appropriate headings : Spindle drive.-The headstock spindle 2lis driven from a constant speed shaft 31 driven either directly by a motor M or through belt gearing. A toothed wheel 32 on the end of this shaft drives through an idler 33 and toothed wheel 35 an " input " shaft 36. This shaft may be connected selectively by clutches 39, 40 and gear pairs 49, 45 and 50, 46, respectively to a parallel shaft 38, this shaft in turn drives an " output " shaft 37 through either of the gear pairs 47, 51 or 48, 52 according to the position of a clutch-operating collar 44. The clutch collar 43 similarly controls the two clutches 39, 40, and thus four different speeds are available at the "out - put " shaft 37. Pick-off gears 53, 54, accessible through a cover in the headstock end of the machine, continue the drive to a layshaft 56 provided with a sliding twin gear 57, 57a, manually controlled to double the range of speeds at the shaft 60. This shaft is connected to drive the machine spindle through the gears 59, 61 and sleeve 62. The latter is splined to the spindle at 63 to enable the spindle to be axially adjusted by a sleeve 64 provided with rack teeth 66 and a hand-operated pinion 65. The housing 20 for the sleeve is split at 67b so that it may be tightened to hold the spindle in its adjusted positions. Feed drive.-The feed drive for automatic operations of the turret and cross slides is taken off the main spindle drive at 68, Fig. 4, and drives through gear train 69, 71, 73, 74 a wheel 75, Fig. 4a (gearing spaced out and shown in plane of paper for clarity). The wheel 75 is splined to a short shaft 76 freely journalled in the end of a feed output shaft 77. Pick-off gears 101-106 transmit the feed drive at different speeds from shaft 76 to three shafts 78-80, each provided with a clutch 81, 83, 85 respectively, which enables either shaft selectively to drive a gear cluster 88-90 on shaft 77 through gear pairs 84, 89 ; 82, 88 ; 86, 90, respectively. A clutch member 96 on the feed output shaft 77 enables either the gear cluster 88-90 to be engaged to drive this shaft for the slow feed movements or a gear 95 to be engaged to drive the shaft at high speeds for all idle movements. The high-speed drive is obtained from gear wheel 99 which is driven in turn by a pinion 97 secured to the spindle of an electric motor 100 rotating continuously at constant speed. The shaft 77 is coupled to a further feed shaft 30 through a safety shear pin device 108-110 and gearing 107, 111. The gearwheel 107 is in adjustable driving connection through face teeth with a bevel wheel 113 which drives through a further bevel 117 and worm gearing 119, 120 a shaft 121 for a speed control device described below. Provision is made at 118a for hand-cranking the feed train when setting up the machine and safety means are incorporated whereby engagement of the handcrank is impossible until the feed clutch 96 is rendered in the neutral position. The motor 100 for the high-speed idle movement also drives through the gear train 123, 124, 127, 128 a constant speed power shaft 126 for supplying the power to operate the clutches automatically. A gear pump 131 for lubricating the gearing is also driven from the intermediate shaft 125 of this train. Turret and saddle.-The turret slide 23, Fig. 2, is of channel form arranged to slide on hardened steel ways 136 secured by bolts 138 to the bed of the machine. Hard steel inserts 139, Fig. 12, are also provided at intervals along the slide faces of the saddle and adjustment for wear is effected (a) laterally-by a gib 140, and (b) vertically-by screwed sleeves 146 and bolts 143 which adjust the position of longitudinal clamping straps 141 and 142. The turret 165, Figs. 5 and 7, is carried in a circular recess at the end of the saddle and rests on a face 168 which is bevelled and overtapped by the turret at h to exclude cuttings. The turret is allowed a small amount of lateral play so that it may be clamped in its indexed positions by a wedge member 175 which forces it to the left against shaped locating segments 170. An indexing ring 178 with slots 176 is secured to the underside of the turret so that the slots may be engaged in the manner of a Geneva mechanism by a pin 180 on a rotating cam 135. This cam is mounted at the top end of a vertical spindle journalled in the machine bed and the lower end of the spindle is driven by worm gearing 148, 151, from the main feed shaft 30 the drive for which was described above. A heart-shaped cam groove 135a is provided in the cam and is engaged by a pin 147, Figs. 7 and 8, which is journalled in a detachable bearing member 163 bolted to the turret saddle. A cam block 182 secured also to the cam 135 is adapted to operate a roller 183 carried by a lever 184 which is pivoted at 185 and is connected at its opposite end with the locking and clamping latch 175. As the cam 135 rotates it thus effects the feed and return of the turret saddle, withdrawal of the wedge member 175 against the bias of spring 190 operating through a cable 195 and indexing of the turret, when the saddle is in its withdrawn position. Cross slides.-The cross slides 25, 26 are identical in construction and are operated in timed relation with the turret feed movement by rods 205, Fig. 9, connected to the saddle and provided with sliders 208 having rollers 215 which engage slots 210 in slides 213 moving obliquely in the cross slide housing 200. These slides also carry rollers 218 which engage oblique slots 220 in the underside of the cross slides 25, 26 and move the latter at the same speed as the turret saddle moves. The cross slides may be operated each time the turret saddle feeds forward or the operation of either may be suspended by a control device s, Fig. 5, which comprises a disc mounted on a vertical pivot in the machine bed which is indexed when the turret is in its rearward position by a pin 240 on the cam 135 engaging slots in a disc 139, a pin 242 engaging the undulating rim of the control disc to hold it in position for a subsequent indexing movement. The control disc is provided with radial recesses 244 into which may be secured tappet members with shaped ends which are adapted to engage the ends of oppositely disposed sliding rods 25c, 26c located in the turret saddle. These rods when pushed outwardly against springs 247, rock shafts 253 and latches 230, Figs. 9 and 9a, to disconnect the operating push rods 205 for the cross slides from the turret saddle, the latches ride over projections r on the push rods and these remain stationary on forward feed of the saddle. When the tappet members are omitted from the disc or their ends turned so that the rods 25c 26c are not operated the latches 230 engage the shoulders r to move the rods 205 forwardly and thus operate the wedge gear for feeding either or both of the cross slides. Speed and feed controlling.-The machine may have its motions controlled automatically, including starting and stopping, change of spindle speeds, change of feed speeds for the turret saddle (including corresponding feed change for cross slides if operated), and introduction of high speed motion for idle movements or, manual control means may be additionally provided. The control means are shown generally at 112, Fig. 1, access to which is obtained through a cover 112a. The first operating shaft 121, Figs. 13 and 14, of the control device is driven from the worm gearing 119, 120 described above in timed relation with the main feed shaft 30. This operating shaft carries a number of spaced discs 260 (A-J) which are slotted to take adjustable dogs 261 (A-J), other dogs such as 342 may be arranged on the discs to operate start and stop electric switches such as 343. The dogs 261 (A-J) and the operating mechanism now to be described are similar for operating each of the speed and feed control clutches but minor modifications are made in the case of some of the control devices, for example, the operating means for changing from high to slow speed feed has an intermediate neutral position and safety means for preventing inadvertent engagement of the clutch part 96. The operation of the dogs will therefore only be described in respect of dog 261A which controls the operation of clutch sleeve 44 for a change of spindle speed by pulling on either the cable 41c or 42c, Fig. 4. The dog 261A operates a spring-pressed tappet 284 to raise a lever 281A pivoted at 282. This withdraws a plunger 270 against spring 280 to allow a ball 262A to drop into a raceway provided in a casing 274 running the length of the control box. The ball falls between spacers 273 provided on a shaft 126 which is rotated at constant high speed as described above from the electric motor 100, Fig. 4a. This shaft also carries keyed thereto collars 271 each with a lobe 272 projecting into the raceways. As the ball dro