Patent GB-604912-A (GB)
Title: Improvements in variable feed mechanism for automatic lathes and like machine tools
IPC: B23Q5/34
Filed: 1944-09-09
Abstract: 604,912. Lathes; actuating machines. WARMAN, R. T. Sept. 9, 1944, No. 17252. [Class 83 (iii)] [Also in Group XXIII] Mechanism for actuating the tool slide of an automatic lathe, a milling, or a grinding machine, provides a variable feed means adapted to produce a combination of motions automatically repeatable and adjustably preset, a variable speed gear imparting motion to a toothed sector or quadrant, a first timing device determining the amplitude of the sector, a second timing device determining the dwell of the sector, a controller for pre-setting all the variables, and interlocking means for preventing operation of the mechanism other than as pre-set. The mechanism which is shown for convenience in three sections, Figs. 1, 2 and 3, is driven from a constant speed shaft, such as the back shaft of an automatic lathe, coupled by a sprocket-chain to the sprocket-wheel 13 and shaft 1. The wheel 13 is coupled to drive the shaft 1 at intervals determined by clutch control mechanism described below and a skew gear 77 keyed to the shaft 1) drives the arm 78 of a Geneva mechanism for rotating a control shaft 2A. Cams 21 on the shaft are arranged to operate in turn, through levers on shaft 22A, a series of controllers 25, 26 (one controller may be provided for each tool position in the case of an automatic lathe, but only one controller is shown for clarity). Part 25 in being pushed downwardly over part 26 produces, through interengaging wedge faces, lateral movement of the latter part. Adjustable stop screws 27 carried in brackets on part 26 are pre-set to displace cams 28 to 31 varying amounts. When the controller shown is operated: (a) cam 28 moves rod 28A which is connected to a gear segment 15A and partially rotates a slotted plate 15. This plate is frictionally engaged with a constantly rotating member 14 and according to the position in which the slot 20 is pre-set a known time elapses before the slot comes around to the vertical position and allows a projection on a lever 18 to be spring- urged therein. The lever 18 is thus, after a predetermined time lapse, rotated and through connecting rod 18A, lever 87 and shaft 88 moves a catch 55 to allow a spring-influenced lever 89 to engage a lever 11 with a cam 12 on the drive shaft 1. This engagement results in a clutch part 3 being released to engage clutch part 7 and so driving the spiral gear for the indexing of cam-shaft 2A and also a number of cams 79 for restoring the parts of the actuating mechanism to initial position ready for a new set of operations; (b) cam 29 moves rod 29A connected to quadrant 16A which similarly to quadrant 15A determines the time lapse before a projection on a lever 17 falls into slot 19 and rotates the lever to operate through a rod 17A a shaft 46A. The latter controls a catch 46 which releases mechanism to engage the drive 51 of an epicyclic change-speed gear-box. This drive passes to the sprockets 52, 43 and to a pair of segments 36, 37, the latter of which is connected to drive, for example, the turret slide of an automatic lathe, Fig. 4; (c) cam 30 connected to link 30A moves a cam-shaft 172 which through lever mechanism lifts one of the selector rods 44 of the epicyclic gear-box to choose the appropriate feed speed required for the tool slide referred to in (b) above; (d) cam 31 operates rod 31A to rotate segment 74 and shaft 67A pre-setting the position of a cam 68 which, as described below, disengages a clutch when the turret on the tool-slide referred to above is indexed to the desired position. The drive for indexing is obtained from a gear-wheel 76 keyed to sprocket 13 on shaft 1 meshing with a wheel on a lay-shaft 70A, Fig. 8, which drives a clutch part 80. The corresponding clutch half 81 is driven except when cam 68 depresses the spring-urged clutch-operating lever 69A as shown. When driven, a projection 71 on clutch-part 81 oscillates lever 65 once for each revolution and this shaft 66A and lever 66 which is connected by means not shown to the turret indexing device. Engagement of the main clutch 3, 7 is prevented until turret indexing is complete by a stop 61 under lever 82, the stop being connected by rod 61A to the lever 69. The main clutch 3, 7 is arranged automatically to engage at the completion of a set of operations by one controller 25 and is then rotated to recondition the various members through cams and link mechanism for a new set of operations by another controller such as 25. The Geneva wheel is also partially rotated to. operate the cam-shaft 2A to depress the controller for the fresh cycle of operations before the clutch is automatically disengaged again. A further timing device for arresting the motion of the turret slide and setting in operation a cross-slide in timed relation with the turret slide comprises a member 40, Figs. 1 to 3, rotating integrally with the shaft carrying the gear segment 36 and sprocket 43, having stepped faces adapted to engage similar faces on clutch members 41, 42 which are shown in an exaggerated spaced-apart relation for clearness. The member 41 is rotated by a shaft 23A, a lever 23 and adjustable lost-motion device 32, 34 from the cams 21 on the shaft 2A similar to the controller operation and the pre-set position of the member 41 determines the time lapse before engagement under spring pressure with the member 40 takes place. When this occurs, a brake 39 is automatically applied to member 40, the turret slide is arrested and the latch plate 45 is moved to disengage the drive from the change speed-box. The member 42 is pre-set in a similar manner to the member 41, but from a shaft 33A, lever 24 and adjustable lost-motion device 33, 35. Engagement of members 40 and 42 actuates a lever 56 to move a latch 57 from below the lever 58 which is thus spring actuated to rotate a shaft 58A and lever 94 controlling the movement of a cross-slide. An indicator is provided for setting the controller screws 27 and lost-motion adjustments 34, 35.