Patent GB-628952-A (GB)
Title: Gear finishing machine
IPC: B23F19/06
Filed: 1945-06-26
Abstract: 628,952. Gear - cutting. NATIONAL BROACH & MACHINE CO. June 26, 1945, No. 16262. Convention date, March 16, 1942. [Class 83 (iii)] [Also in Group XXVI] In a machine for finishing gears by means of a toothed shaving cutter rotating in mesh with the work on a crossed axis, the work is reciprocated axially by a rotating eccentric and simultaneously the cutter is fed into closer mesh with the work by a rotary cam, the cam and eccentric being driven positively in timed relation from a common source. In one form of machine the work G, Fig. 2, is mounted between adjustable head and tailstocks on a slide 15 which is reciprocated horizontally parallel to the work axis by a lever 17 carrying a roller 20 engaging a transverse slot in the slide. The lever is pivoted at 18 on the machine frame and is oscillated by an adjustable-throw eccentric 21 rotating in a yoke 25 of the lever. The eccentric is rotated by a shaft 23 driven by worm gearing 43 and a variable-speed belt drive 41 from an electric motor 35 which is adjustable to vary the belt tension by bolts 37 engaging slots 38 in a supporting bracket 39. The cutter 65 is carried by a head 55 angularly adjustable, for the crossed axis relationship, by means of worm gearing and graduated scales 56, on a table 53 which is vertically adjustable by a screw 58 and graduated scale 59 on a vertical slide 51. The slide 51 is fed during cutting by a scroll cam 88 on a shaft 89 driven through change-gearing 98 and bevel-gearing 96 from the shaft 23, which reciprocates the work. The slide 51 is normally raised and balanced by a spring 85 and the cam has a rising portion a-b, Fig. 4, for feeding the cutter downwards into closer mesh with the work, a concentric portion b-c to produce a finishing dwell on the cutter during the last stroke of the work, and a flat portion c-a to allow the spring 85 to raise the cutter into loose mesh with the work on completion of the finishing operation. The gearing 98 is so arranged that the work makes a complete number of reciprocations during one rotation of the cam 88, after which a plugging relay 100 is actuated by shaft 89 to stop rotation of the motor 35 abruptly. The cutter 65 is driven from the motor 35 through a variable-speed belt drive 80, and worm, change and bevel gearing in the head 54, 55. The cam 88 may provide stepped instead of continuous feed for the cutter. In a modified cutter head a housing 150, Fig. 8, is balanced and normally raised by a spring 154 acting between a bore 157 in the housing and a collar 155 on a fixed rod 156. A nut 170 on the housing is rotatable by a hand wheel 169 and engages a screwed rod 161 slidable in the frame 153 and provided with flats 163 against whose shoulders bears a lever 164 rocked on a fixed pivot 165 by the cam 88, Figs. 1 and 4. Rotation of hand wheel 169 thus adjusts the position of the cutter housing. The cutter head 175, Figs. 5 and 6, has a boss 180 entering a recess in the housing 150 and is rotatable on a supporting pin 182. Angular adjustment is made by a hand-operated pinion 191 engaging teeth 190 on the head and clamping is effected by a wedge 185 actuated by a screw 187 and passing through slots in the housing 150 and pin 182. This adjustment is facilitated by an indicator 196 passing through a slot in the housing and attached to a ring 194 yieldingly held to the cutter head by spring plungers 195. The cutter spindle 200 is driven by bevel-gearing 213, shaft 212 and spurgearing 218, 219 from a shaft 217 co-axial with the pivot pin 182, shaft 217 being rotated by worm-gearing 216 and the variable-speed belt from the motor 35. Spindle-mountings.-The cutter 203, Fig. 6, is mounted on a spindle 200 supported by a removable end bearing 201 and two main bearings 204, 205. To take up end play in these bearings the bush 207 for the inner race of bearing 205 is keyed at 208 to the spindle so that securing a nut 206 on the spindle end will impart end pressure to the bearings, after which the nut may be locked to the bush by a screw 209. Tailstocks.-The work G, Fig. 2; is mounted between rotary ball-bearing centres, one being carried by a spindle pressed towards the work by a spring. A handle retracts this centre to allow removal of the work and on rotation in the opposite direction permits the spring to press the centre against the work, after which further rotation of the handle clamps the spindle carrying the movable centre. Cuttings, catching and removing.-The machine bed 11 is formed with a coolant trough 12 surrounding the. ways 14 for the work slide 15, the trough having an outlet at one end leading to a sump. Variable-throw eccentrics. The eccentric 21 has a transverse central slot 22, Fig. 2, through which the shaft 23 passes, the throw of the eccentric being varied by adjusting two opposed screws 24 engaging the shaft. The eccentric engages hardened wear-plates on the yoked lever 17.