Patent GB-631654-A (GB)
Title: Improvements in or relating to gear planing machines
IPC: B23F5/14
Filed: 1945-01-16
Abstract: 631,654. Gear-cutting. AEPPLI, A. Jan. 16, 1945, No. 1340. Convention date, Dec. 2, 1943. [Class 83 (iii)] In a shaping machine for generating gear teeth by the use of a rack toothed cutter, the tool ram has an indexable carrier provided with a number of parallel cutters which may be brought into action successively so that large gear-wheels or numbers of small wheels may be finished without stopping the machine for change of cutters. In one form a carrier 1, Figs. 1 and 7, has a series of identical rack cutters 2 whose backed-off teeth have a full profile from front to rear, the cutters being integral with the carrier or attached thereto in a manner similar to built-up milling cutters. The carrier is held against the cutting thrust by means of a pivoted dog 7 which may be removed by hand for indexing of the carrier after a number of small gears have been cut or may be removed automatically if indexing is performed during operation of the machine. In the latter case a cam on the shaft 4, Fig. 10, on which the carrier 1 is secured, engages the dog 7 to release it against the action of a spring 45. The shaft 4 is rotated intermittently by a mutilated gear 13 having oppositely located groups of teeth which successively engage a gear 12 on the shaft, the gear 13 being rotated continuously by bevel gearing 21, 22, splined shaft 24, gearing 26 and bevel gearing 29 from a main shaft 30 which also drives the tool ram 37 through a crank 34 and connecting rod 35. The carrier is located in the successive cutting positions by an index lever 16<SP>1</SP> engaging a notched disc 15 on the shaft 4 and lifted against the action of a spring 18<SP>1</SP> by a cam 19 on the shaft 14 of the mutilated gear 13. The carrier may be indexed after each tooth on the work has been completed or after each cutting stroke, and the indexing movement is per- . formed in two stages so that when the cutter is clear of the work at the end of a cutting stroke the carrier will be rotated sufficiently to give clearance with the work for the return stroke and at the end of this stroke the carrier will be further rotated to bring the next cutter into operative position. The disc 15 has twice as many notches as the number of cutters in the carrier to provide for the two-stage indexing. The carrier 1 and indexing mechanism are mounted on a head 38 which is rotatably adjustable about the axis of the bevel gearing 22 on the ram, the latter sliding in guides on a bracket 32 which is also rotatably adjustable on the machine frame 31 about the axis of shaft 30. The work is mounted on a table rotatable about a vertical axis and carried by longitudinal and transverse horizontal slides and is given a rolling generating motion relatively to the reciprocating tool by known mechanism. The tool carrier may be indexed by a Geneva mechanism or a cam. If the work is indexed after each cutting stroke the number of cutters in the carrier may be reduced so that the cutters will clear the tops of the work teeth on the return stroke, or if more cutters are used the carrier may be mounted in a clapper box. By using fewer cutters the length of the individual teeth in a circumferential direction may be increased to increase the useful life of the cutters. If the machine completes the cutting of a tooth on the work before indexing the latter, the indexing motion for the carrier is derived from the work indexing mechanism instead of from the ram drive. Each rack cutter may have truncated entering teeth, or some of the cutters may have thin roughing teeth whilst others have finishing teeth, in which case the carrier is indexed manually. When cutting helical wheels, cutters 57, Fig. 20, with inclined teeth and stepped leading edges may be used in order to shorten the working stroke h as compared with the stroke h<SP>1</SP> required for cutters such as 60.