Patent GB-929454-A (GB)
Title: Automatic lathe
IPC: B23B13/00
Filed: 1962-02-26
Abstract: 929,454. Automatic lathes. USINES TORNOS FABRIQUE DE MACHINES MOUTIER S.A. Feb. 26, 1962 [March 1, 1961], No. 7339/62. Class 83 (3). An automatic lathe comprises a first device for driving the spindle at high speed, a second device for driving at low speed, clutch means for connecting the spindle to either of the devices, a braking device connected to the spindle when it is unclutched from the high speed drive, comprising a fixed member, a movable member rotatable relative to the fixed member in a direction opposed to the high speed direction of the spindle, and means for instantaneously connecting the spindle to the movable member The lathe comprises a headstock 1 movable along a slide 3 by cams on a cam-shaft 4, against a spring 5, Fig. 1, a hollow spindle 14 driven at high speed by a pulley 31, and in the reverse direction at low speed by a pulley 32, and a bar guide 6 having turning tools 10 mounted fanwise thereabout, the tools being controlled by cams on shaft 4. A chuck 17 is opened by a spring 16 and is closed when the spring is compressed by moving a sleeve 15 axially by rockable dogs 19 actuated by a stirrup 23 pivoted about a pin 24, a follower 26 on the stirrup engaging a yoke 27 rockable by cams 30 on shaft 4. Pulley 32 is rotatable on a sleeve 35 keyed to spindle 14 and clutch 38 selectively engageable with pulley 31 or 32, by cones 41 and 39, drives sleeve 35 and therefore spindle 14 by a finger 40. Clutch 38 is controlled by a spring-urged lever 44 having a nose 44a with a jointed follower 48, the lever being pivotable about a rod 46 by a yoke 49 rockable on a rod 50, by lobes 55, 56, on a cam 54 which engage followers 52, 53, on the yoke. Clutch 38 is moved to engage high speed pulley 31 when follower 52 is lifted by lobe 55, and a detent 58 pivoted at 59 is moved by a spring 60, so that an adjustable stop 61 engages a stop 62, to hold the clutch in this position. After the turning operations have been carried out with pulley 31 driving spindle 14, the latter is stopped and indexed three times through an angle of 90 degrees with pulley 32 driving, to allow the further operations to be carried out. The indexing device controlled by two cams 63, 64, on shaft 4, Fig. 4, which actuate two rockers 65, 66, pivoted on a shaft 96, the rockers having screws 67, 68, which engage levers 69, 70, to rock the latter about a shaft 97. The levers have projections 73, 74, carrying screws 75, 76, which co-operate with inclined surfaces 77, 78 on detent 58, so that as levers 69, 70 are rooked, detent 58 is rocked, and stop 61 releases stop 62, thus allowing spring 57 to pivot lever 44 which disengages the clutch from pulley 31 and engage it with pulley 32. Levers 69, 70 also have arms 79, 80, which carry adjustable latches 81, 82, co-operating with indexing discs 83, 84, the former disc being keyed to sleeve 35, and the latter freely mounted on the sleeve, the discs being angularly adjustable relative to each other by toothed end faces 134. Discs 83, 84 have two diametrically opposed notches 98, 99, and latches 81, 82 are held against the discs by springs 86, 87. Before pulley 32 takes over the spindle drive from pulley 31, the spindle has to be stopped, and a brake is therefore provided. The brake comprises a ring 90, Figs. 1, 5, non-rotatably fixed in the headstock by a pin 91, and a disc 92 keyed to pulley 32 having cut-out portions 93 carrying rollers 95. Pulley 31 rotates spindle 14 in the direction c (clockwise), Fig. 5, at high speed, and a belt 37 drives pulley 32 in direction b (counter-clockwise), at a low speed. After the turning operations are completed clutch 38 is moved to connect the spindle with pulley 32, and the spindle is still rotating clockwise at a high speed due to its inertia. Pulley 32 therefore tends to rotate clockwise with belt 37 slipping, but is prevented from doing so by rollers 95 which are wedged in cut-outs 93. The spindle is stopped and belt 37 then rotates pulley 32 and spindle 14 counter-clockwise at a low speed, whereupon cams 63, 64, control the indexing of discs 83, 84 to stop the spindle to allow further operations, e.g. milling or boring, to be carried out on the bar stock. In a modification, the sliding of belt 37 on pulley 32 is avoided by having a sliding mechanism in the belt drive. In a further modification, the cam controlling lever 44 is shaped so as to hold clutch 38 in neutral when the spindle 14 is at rest, i.e. disconnected from both pulleys 31, 32. Cams 63, 64, 83, 84 may have various shapes according to the required indexing positions of spindle 14.