Patent GB-382950-A (GB)
Title: Improvements in or relating to automatic lathes and the like
IPC: B23B13/00
Filed: 1931-05-20
Abstract: 382,950. Lathes. HAHN, H., HAHN, O., and TESSKY, K., (trading as INDEXWERKE, HAHN & KOLB), Esslingen-on- Neckar, Germany. May 20, 1931, No. 14853. Convention date, May 20, 1930. [Class 83 (iii).] In an automatic lathe working or bar stock, the feed tube is provided with a plunger device which feeds forward a reserve stock bar so that it follows up the bar being worked, the plunger being finally displaced when the first bar is used up, by a distance sufficient to eject the remnant of the first bar and bring the reserve bar into operative position in the feed collet. In Fig. 1 the collet is controlled by a member 3 operated from a cam 4 and the feed fingers are controlled from a member 5 operated by a cam 6, a work stop 7 being arranged to determine the forward feed of the stock. The cams 4, 6 are formed in a drum mounted on a main cam shaft 9 which is also connected to the axially moving slide 11a. The cam shaft 9 is driven from a pulley 16 through two-speed gearing 53 .. 56, countershaft 15, and a shaft 13 and worm gearing 12. The stock bar is guided in a tube 18 mounted in standards 19, 20 and is adapted to swing about the axis of the standard 20 on a pivot 21 so that a fresh stock bar can be inserted from the machine end as soon as the bar being used has passed out of the tube 18. The reserve bar is engaged by the plunger 23 which is urged forward by weights 28, 29, attached to a cable 26. The plunger 23 is connected through a rod 30 with a sleeve 31 carrying a trip finger 32 coacting with a bell-crank lever 33 connected by brake 34, lever 36, and rod 37 to a bell crank 38 which controls a spring-urged clutch member 47. The clutch is normally urged into engagement with a member 41 keyed to an auxiliary cam shaft 42. One end of this shaft carries a Geneva wheel 43 actuated by a pin wheel driven from the main cam shaft 9. The shaft 42 carries a loose cam drum 48 on the hub of which the clutch 47 is keyed. The clutch is engaged to lock the cam drum to the shaft 42 when the bell crank is moved to the Fig. 1 position and after one revolution the bell crank, having dropped into a cam groove 47a, disengages the clutch. The cam groove 50 in the drum 48 controls the two-speed gearing selector 51 and the cam groove 49 controls a bellcrank lever 57 engaged by the end of a lever 59 connected to a member 65 provided with spring jaws which may engage over the end 69 of the sleeve 31. During the movement of this sleeve to the right the nose 69 passes between the spring jaws and the sleeve may then be moved further to the right by corresponding movement of the jaw member 65. This mechanism is interconnected by means of a rod 70, and cam segment 72 to a bar 74 geared to the oscillating work stop 7. The stop is normally operated at the required times by a cam 78, Fig. 5, on the main cam shaft. In operation, when the bar 8 being worked is almost exhausted, the stop 32 engages the bell crank 33 thus releasing the clutch 47 and causing the cam drum 48 to be driven intermittently by f r a ctions of a revolution by the Geneva mechanism. When the last of these movements occurs the bar 8 has reached a length where it can no longer be fed forward by the full feed distance. At this point the change-speed mechanism is actuated by the cam groove 50 to drive the main cam shaft at a lower speed during the ejection of the remnant of the stock bar. At the same time the lever 57 is operated and this engages link 59 with a projection of a lever 80 connected to the operating lever 80d, Fig. 14, of the feed mechanism 5. The weight 29 has now been brought to rest and the weight 26 acts alone on the plunger to keep the cable 26 taut. The operation of the lever 59 by the lever 80 draws forward the jaw member 65 and also the sleeve 31 and the plunger 23, thus feeding the reserve stock bar forward by a distance greater than the normal feed distance so that the remnant of the old bar is ejected and the reserve bar is placed in a position to be gripped by the collet. The work stop is moved aside during the ejection of the remnant. After this action the cam 50 changes the two-speed gearing on to the high speed for the normal drive of the main cam shaft. The new stock bar is then fed normally until it leaves the guide tube 18 at which point the operator can swing the guide tube round its pivot to insert another stock bar, thus pressing back the plunger 23, raising the weights 28, 29, and disengaging the member 69 from the jaws 65. A visible indicator is actuated when the bar being worked passes clear of the tube 18. In a modification, Fig. 11, the shaft 42, and associated parts are omitted and the lever 59 is raised into engagement with the feed mechanism for the ejection of the remnant by means of the lever 36 and bell crank 33. The lower arm of the lever 36 controls the change speed mechanism of the main cam-shaft drive. In another modification, an extension of the main cam shaft carries a cam which operates the feed jaws 65 for ejection of the remnant and the cam shaft is rotated at constant speed. In another modification, Fig. 16, for hand operation, the machine is stopped when the bar being worked is exhausted and the jaws 65 are operated to insert the fresh bar by means of a pedal 93 whose movement may be limited by a stop. Other modifications are also described.