Patent GB-599664-A (GB)
Title: Improvements in or relating to automatic lathes or screw machines
IPC: B23B7/04
Filed: 1946-02-04
Abstract: 599,664. Lathes. PORTERFIELD, W., MARSON, L. J., and MAIN ENGINEERING CO., Ltd. Feb. 4, 1946, No. 349.5. [Class 83 (iii)] Means for controlling the indexing and traversing movements of the capstan of an automatic lathe or screw machine of the kind in which an intermittently operated mechanism is adapted to traverse the capstan slide during periods between successive cam-operated toolfeeding movements, incorporates an adjustable lost-motion device settable to predetermine the traversing thereof before it effects the return of the capstan-head to a position in proximity to the work for a fresh cam-operated feed movement. The machine to which the invention is applied is similar in general construction to that described in Specification 599,620. In the present arrangement, however, an automatically operated capstan slide 59, Fig. 1, carried by a saddle 62 adapted to be clamped in adjusted positions on the tubular guides 44, is provided. The capstan slide 59 is fed during tool operation by the inclined portions 65 of a cam drum secured to the shaft 32. Gaps are provided in the cam drum to permit of the capstan slide being withdrawn rapidly from the work, beyond the normal feed traverse, for indexing, a locking finger 67, Fig. 5, being operated simultaneously with the indexing, which is effected by a ratchet-wheel 60 secured to the capstan 56 and a finger 66 secured to the saddle. A cover 72 is provided to exclude chips from the capstan pivot. Springs 82 hold a roller 64, secured to the capstan slide, in engagement with the cam lobes 65 and assist in the withdrawal of the capstan slide for indexing.. The reciprocation of the capstan slide beyond the feed range is derived from adjustable collars 113, 112 secured to a rod 111 which moves the capstan slide backwards and forwards with a certain amount of lost-motion according to the working feed movement required. The rod 111 is reciprocated in timed relation with the cam-shaft through linkage 108, 109, from a crank arm 107 secured to a rotatable disc 96. This disc is coupled to another disc 95, Fig. 8, both discs being loose on a crossshaft 92, Fig. 6, which drives the cam-shaft 32 through worm gearing 41, 34. A sleeve 93, Fig. 8, secured to the shaft 92 and located between the discs, has a rim 94 with a notch 94a. A pawl 98 is spring-urged into engagement with the rim 94, but is pivotally carried on the disc 95, and is normally held out of engagement with the notch 94a by a pawl 101 carried by a cross-shaft 91. A further arm 105, Fig. 1, secured to the shaft 91 carries a roller 104 which engages a notch in the disc 96 to hold it against inadvertent rotation. The camshaft 32 carries, at its headstock end, a control plate 88 with replaceable projections 89, Fig. 3, which intermittently strike a tappet 90a, Fig. G, on an arm 90 secured to the cross-shaft 91. At each tappet operation the pawl 101 and roller 104 release the discs 95 and 96 and, when the notch 94a in the sleeve 93 lines up with the pawl 98, these discs are rotated and the rod 111 is reciprocated to index the capstan. The motion continues until the pawl 101 lifts the pawl 98 and the roller 104 engages again the notch in the plate 96. No further movement of the rod 111 takes place until the tappet is again operated, but the inclined surface of the cam drum 65 takes over to feed the capstan slide for the working portion of the stroke.