Patent GB-399992-A (GB)
Title: Improvements in machines for cutting screw-threads
IPC: B23G1/22
Filed: 1932-10-31
Abstract: 399,992. Screwing taper threads. LANDIS MACHINE CO., Waynesboro, Pennsylvania, U.S.A. Oct. 31, 1932, No. 30491. Convention date, Sept. 29. [Class 83 (iii).] Threads of various tapers and lengths may be cut on stock 11 gripped and rotated by chucks 8 and 9 while a carriage 28 carrying the dies 42 is advanced over the work by a feed screw 29, the dies being gradually opened by a cam ring 43, which is gradually turned round according to the incline to which the sloping bar 58 is set. As the carriage 28 is traversed the sloping bar 58 rotates the cam ring 43 by moving up the rack bar 51 which moves round the segmental toothed piece 49 attached to the cam ring 43. The work 11 is held in spaced chucks 8, 9 closed by levers 12 and a fluid pressure &c. motor 26, the chuck 9 having resiliently mounted gripping wheels 21. The initial spacing of the dies is set by a handlever 66 operating the cam ring 43, while a close setting for a rough and a finishing cut is obtained by a hand-lever 75 with a spring- pressed pin 79 engaging a cam 76 in one or other of two close positions. Micrometer adjustment of the dies is provided by the bolt 73 and screw scale 74. A hand-lever 27 operates a motor 26 to cause the chuck 8 jaws to grip the work. A small eccentric half-roller 45 with screw bolts 47 allows another adjustment of the dies. The carriage is then moved by hand-wheel 34 or rack and pinion to the right until it strikes a stop screw 86 when further movement registers the length of thread to be cut on the scale 88. The carriage is now moved to the right until the cutters just touch the end of the work after which the bracket 84 is advanced until the stop screw 86 touches the end of the bar 56 on the carriage. The carriage nut is now closed on its feed screw 29 and advances the cutters over the work at the required relative speed. When the thread has been cut as indicated by the coinciding of the zero marks on the scale 88 the hand-lever 66 is raised to separate the dies and the carriage nut is again disconnected by hand from its feed screw, but this may be done automatically. The machine may be operated semi-automatically by compressed air or hydraulic means, Fig. 8. Here the work 11 passes through the holders 8, 9 until it contacts against a stop 96. A valve 97 is actuated by hand to admit fluid pressure to ducts 98, 99. From duct 98 the piston 102 turns the stop 96 clear of the work 11. From duct 99 the fluid pressure passes through valve 113 to cylinder 103 on the carriage 28 which advances (to left) as the piston rod 105 is anchored, until the dies contact with'the end of the work 11. Hand-lever 89 now clamps feed nut round its feed screw 29, and also shuts off fluid pressure from the cylinder 103. Cutting proceeds until a stop on the carriage turns lever 107 to actuate valve 108 to actuate a piston 111 which turns the cam ring 43 and opens the dies. Simultaneously the cam 91 engages lever 92 with arm 112 to open valve 113 to admit fluid pressure to the outer end of cylinder 103 thereby retracting the carriage 28 from the work. The cam 91 and lever 92 also opens the nut on the feed screw 29. The cam 114 on the carriage actuates a valve 97, resets the stop 96, and also cuts off the pressure in cylinder 103 to stop the carriage and also closes the dies for cutting.