Patent GB-627288-A (GB)
Title: Improvements in gear cutting machines
IPC: B23F5/20
Filed: 1945-10-24
Abstract: 627,288. Gear-cutting. GLEASON WORKS. Oct. 24, 1945, No. 28080. Convention date, Nov. 9, 1944. [Class 83 (iii)] A machine for generating gears and particularly spiral bevel-gears comprises a worksupport, a work-spindle journalled therein, a face mill cutter rotatably mounted on a tool-support, means for moving the worksupport from loading to working position, separate means for effecting relative feed movement between the tool and work-supports, and means for effecting relative rolling movement between the tool and work-supports when cutter and work are in engagement to generate the tooth profiles characterized in that further separate means is provided for effecting during generation relative movement between tool and work-supports in the direction of the axis about which the generating roll takes place. The bed 15, Fig. 1, of the machine is formed at one end with an upright 16 in which the cradle 17 for the face mill cutter C is arranged to be oscillated. A sliding base 20 for the workpiece is carried on ways provided on the horizontal portion of the bed. The cradle 17 is provided with an eccentric bore in which is adjustably mounted a cutter carrier 25, Fig. 2, this is itself bored eccentrically to take the rotating cutter spindle 26 for the cutter C. The cutter carrier is adjusted prior to a cutting operation in accordance with the desired spiral angle of the teeth to be cut. The cradle is rocked during engagement of the cutter with the work by means of a cam 100, Fig. 2, secured to a flange 112 on a shaft 113 and operating through a two-armed lever 101, one arm of which is of adjustable throw and connected at 105 to a link 104 which is in turn fastened at 108 to the cradle 17. A return oscillation of the cradle takes place on disengagement of the cutter and workpiece, the latter rotating continuously and being in position for the next tooth space to be cut on re-engagement of the cutter and workpiece. This return movement of the cradle is effected through the control cam 100 and a spring and weight arrangement 133, 126 operating through a chain 127. The camshaft 113 is continuously rotated during operation of the machine from an electric motor and gearing, including pick-off gears. The same motor also drives through further pick-off gears the cutter spindle 26, Fig. 1, and through the overhead shaft 192 and a telescopic drive, to the workpiece spindle 35. Further pick-off gears for the latter to vary the number of teeth to be cut in a workpiece are provided in a gear-box 204 forming part of the verticallyadjustable head on which the workpiece is carried. This head is carried by an upright 50 and may be swivelled and clamped in adjusted position about a pivot bolt 75, Fig. 1, secured to the slide 20 to adjust the machine according to the bevel angle of the workpiece. The slide 20 is reciprocated to feed the work into and out of engagement with the cutter by means of a cam track 135, Figs. 1 and 8, cut in a control-member 134 slidably keyed to the shaft 113. A roller 143, Figs. 3 and 8, secured to a block 141 engages the cam-track 135, the block is pivoted about a shaft 140 and pivotally carries at one side a lever member 146 with a roller 148 adapted to engage a peripheral cam 138 on the control member 134, and a further roller 150 adapted to engage a slot 151 in a member arranged on the underside of the slide 20. The motion of the roller 150 is thus compounded from that imparted by the cam-track 135 and peripheral cam 138. The slot 151 is provided in a plate 152, Figs. 3 and 6, rotatably adjusted by a worm 161 and hand control 164, which is in turn slidably mounted on the underside of the plate 20, but may be clamped thereto by a tapered wedge-member 178. When the plate 152 is in the position shown in broken lines, Fig. 6, the peripheral cam 138 has no effect on the reciprocation of the slide 20 and consequently the workpiece, but when at an inclination to the position shown a further reciprocation is imposed on the slide in accordance with the profile of the cam 138, which is, over its effective circumference, in the form of a spiral with constant lead. The extra movement thus imparted to the workpiece takes place during the cutting action and is stated to eliminate " bias bearing." The control-member 134 is grooved at 136, Fig. 8, and is engaged therein by a roller 187 on the end of a crankpiece 187 which is moved by a lever 185. Manipulation of this lever by hand enables the controlmember and thus the block 141 to be moved, and the table 20 to be traversed either up to the cutter ready for a cutting operation or with the workpiece withdrawn sufficiently to remove it from its holding means. A projection extending from the end face of a flange 210, Figs. 3 and 8, secured to shaft 113, operates a lever 212 once for each revolution of the shaft and depresses an electrical counter 214 so that. when the desired number of teeth have been cut the machine is automatically stopped. When the helical motion of the cam 138 is not employed the depth of engagement of the cutter and workpiece is gauged by a dead-stop member 172, Fig. 6, secured to the bed, which is engaged by a stop-lug 170 carried by the plate 152, the lug is moved out of operative position when the plate is moved to give the slot 151 an inclined position. U.S.A. Specification 1,980,365 is referred to.