Patent GB-221179-A (GB)
Title: Improvements in or relating to lathes and the like
IPC: B23B7/14
Filed: 1924-02-26
Abstract: 221,179. Lodge & Shipley Machine Tool Co., (Assignees of Bird, E. S., and Cockburn, F. B.). Aug. 31, 1923, [Convention date]. Lathes.-In a lathe having a cross tool-slide mounted upon the usual sliding carriage, the carriage is traversed by a propelling member actuated by a feed-shaft which has an automatic and adjustable multi-speed power drive and is also adapted, when the carriage is at rest or moving at a slower rate than the propelling member, to effect the cross-feed of the tool to the work. Two carriages, mounted on opposite sides of the work-spindles are provided, each having separate actuating-gear adapted either for simultaneous or independent control, and either sliding or surfacing cycles may be automatically performed after initial starting by a hand-lever. The machine base 1 is in the form of an oil pan and is provided with an oil pump 4. The front carriage, 9 is supported against downward cutting strains by a gib 15, Fig. 13, while the upward thrust on the rear carriage 10 is carried by the gib block 17. Further bearing surfaces 12, 13 are provided near the machine base and the lower portions of the carriage aprons 49 are guided between the surfaces 12, 13 and guide strips 53 which are bolted to the bed and are provided with T-grooves to which adjustable catch-plates 56 may be secured. The feed screws 25, 26 for the front and rear carriages respectively are driven from control boxes 28 and each screw passes through a cylindrical sleeve 63, Figs. 13 and 14, mounted in the apron and having inwardly-projecting rack teeth 64. Each sleeve is secured to a feed nut 75, and to a trip block or traveller 68, the latter being bored to receive a screwed and slidable control shaft. 29 having pairs of stop nuts 31, 32 and a sleeve 31<a>. A modified arrangement of control shaft stops is described. One of the end walls of each apron is closed by a stop plate 80 and the other by an adjustable screwed sleeve Sand when a feed screw is rotated the toothed sleeve and feed nut can move between the plate 80 and stop S without imparting traverse to the carriage. This movement is utilized to impart cross-feed to the tool either angularly or transversely of the work by means of a vertical shaft 96 having a pinion 100 engaging the toothed sleeve and, at its upper end, a pinion 97 engaging a rack on the tool slide 92. The latter is mounted on a swivel block 44 angularly adjustable on the carriage. When the sleeve 63 engages the stop S any further movement towards the headstock causes traverse of the carriage while cross-feed of the tool is positively prevented, the carriage feed continuing until the trip block 68 engages the nuts 32 and actuates the rod 29 controlling the screw driving gear. Hand wheels H are provided for the manual operation of the feed screws for setting purposes. In order to prevent movement of the carriage during the cross movement of the tool the carriage may be frictionally locked to the frame by means of a friction wheel 102, Fig. 2, mounted on a stub shaft in the apron and engageable with the catch-plate 56 adjustably mounted on the bed. Similarly, to prevent movement of the cross slide while the carriage is moving, as is required while the carriage moves up to its starting position before a facing operation, the friction wheel on the carriage may be engaged with a finger 101 carried by the traveller 68. The controlling mechanism of each feed screw causes the following sequence of movements : rapid crossfeed of the tool towards the work; slow feed to the required depth of cut, cutting traverse of the tool to end of cut; friction feed to a positive stop; pause of tool after end of cut is reached to clean up the cut; rapid withdrawal of tool from work to full retracted position; and return traverse of carriage to its starting point. The drive shaft 110, Fig. 6, coupled to the feed screw, carries loose bevel gears 139, 140 driven in opposite directions from a bevel 148 and coacting with the splined high-speed clutch member 118 operated by the clutch fork 116 which has spaced projections engageable by a member 148<a> mounted on a shifter shaft 114 connected to the control rod 29. The drive shaft also carries a loose worm-gear 129 actuating the slow feed and cutting movements, this gear being fitted with clutch teeth adapted to engage teeth on the splined low-speed clutch member 119. A friction ring mounted within a socket of the worm wheel is provided with notches adapted to engage a pin 136 in the clutch member. On the forward end of the drive shaft is keyed a spur gear 127 integral with a worm 126 and an extension of the low-speed worm has keyed upon it a gear 150. The gears 127, 150 engage friction discs 155 on a. shaft 111, two of these discs being arranged to drive the screw after the low-speed clutch is disengaged until a stop 200 on the control shaft engages the wall of the control box positively to stop the feed. The shaft 111 also carries a pause cam member 165 having a projection 165a and adjustable to vary the duration of the pause from an index disc 176. The cam member coacts with a projection on a block 184. The friction discs and pause cam member are under the action of a spring 166 which is compressed by means of a lever 194 connected to the control shaft coupling so that when the control shaft is moved to the left pressure is exerted on the spring to compress the friction discs and cause rotation of the pause cam. When the end of the cut is reached the discs 155 thus rotate the shaft 111 which through further mechanism engages the reverse movement clutch after the cut has been cleaned up. The clutch forks 116, 117 are interconnected by a compressed spring, separation of the clutches being limited by the flanges 202, 203. When the high-speed is engaged for rapid approach of the tool to the work the slow feed is automatically held out of engagement by means of the pin 136 on the slow-speed clutch which overruns the friction ring mounted in the low-speed worm wheel 129 so that the clutch is cammed out of engagement as shown in Fig. 39. As soon as the high-speed drive is disengaged the drive shaft is stopped and the friction ring then overruns the clutch pins thus bringing the pin into the notch 135<a> and letting in the low-speed clutch. The clutches controlling the high-speed tool approach and the low-speed cutting movements are thrown out by means of a trip shaft 113 having a sleeve engaged by a pivoted lever 210, provided with notches engaging a pivoted pawl on the frame. When the notch 221 engages the pawl the low speed is engaged, while when the forward high speed is engaged the notch 220 engages the pawl. The shifter shaft is moved to the right at the commencement of a cycle this causing the engagement through the clutch fork 116 of the high forward speed and moving the trip shaft to the left to disengage the slow-speed feed clutch. At a predetermined.point a lever 260 is actuated by a trip cam device to withdraw the high speed and to engage the low cutting speed which is in turn withdrawn and all clutches disengaged, the lever 210 being then held as shown in Fig. 5 by the upturned end 225<a> of a second catch. At this point the dead stop of the control shaft engages the box wall. After the cut has been cleaned up the pause mechanism causes the engagement of the return high-speed clutch which is in turn withdrawn by the shifter 148<a> when the carriage reaches its starting position. The trip cam controlling the withdrawal of the clutch to arrest the high-speed approach movement of the tool is mounted on a cross-shaft 230, Fig. 9, and is provided with means adjustable from an external milled head M to control the precise moment of clutch withdrawal. An external lever A, connected to the trip mechanism, may be actuated to disengage the slow traverse and engage the high-speed return if it is required to return to the starting point some time during a cycle. The power is derived from a main pulley shaft 320 having a clutch (not shown) and connected through multi-speed gearing 331 with the spindle back gear 338, the spindle having a clutch 340. The change-speed gearing 331, spindle clutch, and pulley clutch are controlled from levers E, G, I respectively. A helical gear 345 on the spindle is arranged to drive the slow feed for both feed screws, being connected through auxiliary cross-shafts 350, change-gears 352 and spur gears 360 to the worm shaft driving the respective low-speed worm wheels 129. The highspeed feed screw drives are obtained through gearing 376, bevel gearing 381 and cross-shafts connected to the driving bevels 148. The latter are integral with helical gears 391 driving vertical oiler sleeves 393. A starter shaft 280 having handles F at each end which are interconnected with further levers B mounted in the same plane as the levers F, the arrangement being such that the levers B may be used to start either feed screw independently of the other while actuation of either lever F starts both the feed screws. The levers F are connected to shoes engaging grooves 287 of the control shafts. A safety coupling is provided between the drive and feed screw shafts. The end of the drive shaft accommodates a coupler shaft 123 mounted in ball and thrust bearings and having a sleeve with projections engaging notches on the sleeve 125. The coupler shaft is left-hand threaded at the end to a flanged sleeve 309 also connected to the feed screw. The sleeve, and a disc on the coupler shaft are further connected by breaking pins 316 which shear under excessive load, whereupon the continued rotation of the drive shaft will force the sleeve 309 and feed shaft to the right and release the tool from the work. In a modification of the safety mechanism, a clutch is arranged between the drive shaft and feed screw which slips when overloaded, the overrunning of the clutch teeth causing a clicking sound which gives audible warning to the operator,