Patent GB-446071-A (GB)
Title: Improvements in or relating to machines for fashioning articles successively from bar stock
IPC: B23B7/02
Filed: 1935-10-02
Abstract: 446,071. Lathes. BROWN & SHARPE MFG. CO., Providence, Rhode Island, U.S.A.- (Assignees of Rich, C. A.) Oct. 2, 1935, No. 27205. Convention date, Oct. 11, 1934. [Class 83 (iii)] An automatic screw machine including forming and cutting-off tools which form and then sever successive articles from the bar, has means which on starting a fresh bar maintain the forming tool out of engagement with the work during the operation on the first piece. In the application to a machine of the kind described in Specification 300,619, [Class 83 (iii)], the bar stock is fed through a chuck 14 against a stop 15. There are two cross slides 16, 17, one of which carries the cut-off tool 18. Other tools are carried in a turret 20 mounted on an axial slide 19. A main driving shaft 21 is connected through gearing 28, and worm gearing 32 to a cross shaft 36 which is connected by bevel gearing 40 to the main cam shaft 42, Fig. 5, and by gearing 46 to an auxiliary cam shaft 44, both of these cam shafts being arranged to rotate once for each complete piece-producing cycle. The clutch 47 controlling the chuck operation is splined on a sleeve 48 connected by gearing 96 to another cam shaft 88. The clutch 47 coacts with a keyed clutch member 49 and is normally held disengaged by a lever 51 operated from the main cam shaft to impart periodically a single revolution to the cam shaft 88. The cross slide 16 is operated from the main cam shaft through a cam 53, segmental lever 56 and rack 55 while the slide 17 is operated from a cam 54, segmental levers 64, 70 and rack 74. The stock stop 15 is operated from cam shaft 88 through cam 86, lever 82, rack 80, and rack gearing 78. The turret slide 19, Fig. 3, is actuated from a cam 120 on the cross cam shaft 44 through a lever 110 and rack 116, and the turret is indexed by Geneva mechanism including a wheel coacting with a pin mounted on a gear driven by a gear 140 connected by gearing 150 to a gear 148 on a one-revolution clutch member 142 coacting with clutch teeth on the member 49 and operated from the main cam shaft by a lever 152. The machine is provided with a magazine 160 containing additional stock bars and operated as described in Specification 300,619. The advance of the timing rack 168 is arranged on completion of the last article from the old bar to engage an abutment 170, with the starting lever 172 to disengage the main machine clutch 24 and also to operate a rod 175 to maintain the stock stop in raised inoperative position. The advance of the timing rack also causes engagement of a clutch 182 to cause a new bar to drop. The turret indexing mechanism is maintained out of operation during the first operation of a new bar. For this purpose a control lever 200, Fig. 6, engages the indexing clutch member 142 and also carries a pointed pin 210 coacting with a, cam 212 on the chuck clutch 47. The lever 200 is normally held inoperative by a pin 216. An offset arm 220 of the control lever coacts with a cam bar moving axially with the control rod 175 which disengages the stock stop on operation of the replenishing mechanism. Thus when the rod 175 is operated, the cam rocks the control lever 200 in a clockwise direction, Fig. 6, to engage the pin 206 with its groove, thus locking the turret indexing clutch 142. This position is maintained during the whole of the first operative cycle until the chuck clutch 47 is actuated to release the bar for a fresh feed. This causes the cam 212 to return the lever 200 and unlock the turret indexing clutch which then operates in the normal manner. Further mechanism is provided for preventing movement of the turret slide during the first cycle on a new bar. For this purpose a clutch member 240 is included in the drive of the gear 45 which operates the cam shaft 44. This clutch is controlled by a yoke connected by a link 250 with the control rod 200 so that when this rod is operated to lock the indexing clutch, the clutch 240 is disengaged, thus stopping the cam 120 which effects the turret reciprocation. If desired the link 250 may be disconnected so that only the turret indexing mechanism is rendered inoperative for the first cycle. Similarly, by slacking back the screw 206, the turret locking mechanism may be rendered ineffective.