GB556347A - Improvement in gear finishing machines - Google Patents

Abstract

556,347. Gear cutting. FELLOWS GEAR SHAPER CO. June 25, 1942, No. 8739. Convention date, July 1, 1941. [Class 83 (iii)] In a machine for finishing gears with a crowned form of tooth by shaving or lapping wherein the gear and a conjugate gear-like tool are rotated in meshing relation, the gear is mounted on a table which is oscillated about an axis transverse to the gear and tool axes to produce the crowning by means of a reversible motor with timed reversing mechanism. The machine is generally similar to that described in Specification 537,891, the work gear being supported between centres 1, 2, on a table 5 pivoted on a vertical axis 20 which is offset from the tool axis and preferably intersects the line of centres 1, 2. The tool T, which may be either a shaving or a lapping tool, is mounted in an angularly adjustable head 7 on a carriage 8 which reciprocates on ways on a depth-feed slide 10. The head 7 is adjusted around a horizontal axis intersecting the tool axis to permit the meshing of tool and work gears of different helix angle. The means for driving the tool gear and feeding it to depth may be as described in Specification 537,891. The carriage is reciprocated from a reversible motor 15 through gears 16, 17, shaft 18, gears 19 and screw 13. If the work table is set with the line of centres parallel to the tool path, uncrowned gears may be finished. The work may also be adjusted axially so that if desired unsymmetrical crowning may be obtained. Oscillation of the table is effected by a motor 31 connected by gears 34 to a screw 23 mounted at one end in a bearing 24 and at the other, carried in a nut 22 suspended from a bracket on the table by a pivot 27. The oscillations of the table are limited by adjustable screw stops 36, 37, Fig. 5. Both motors are controlled by a cam disc 48, Fig. 1, driven through worm gearing 43 from an extension of the carriage lead screw. The disc carries adjustable strikers 49, 50, coacting with a switch lug 51 to effect reversal of the carriage motor 15, the spacing of the strikers determining the stroke of the carriage. Another cam 53 adjustable on the disc coacts with a rod 55 to operate the reversing switch of the motor 31 to reverse this motor at any desired point in the carriage travel. Swinging of the table may occur rapidly during a small part of its carriage travel so that a crowning effect as shown in Fig. 8 may be obtained, the teeth being of tapered form with arcs a<SP>1</SP>, a joining the opposite tapers. By speed reduction between the motor 31 and screw 23 these arcs may be lengthened or may embrace the entire tooth length.