GB409966A - Improvements in gear generating machines - Google Patents

Abstract

409,966. Gear-cutting. SYKES, W. E., 33, Gates Circle, Buffalo, New York, U.S.A. Aug. 22, 1933, No. 23348. Convention date, Dec. 12, 1932. [Class 83 (iii).] In a gear-generating machine, the blank, while rotating on its own axis, has a planetary motion around a generating cutter 3 and travels past successive circumferential portions of the cutter which gradually cut the teeth to full depth as the cutter reciprocates in a direction transverse to the plane of travel of the blank. The cutter 3 is carried by a vertically reciprocating ram 2 while a number of blanks 5 arranged round the cutter, are secured on spindles 7 mounted in a rotatable table 4. During rotation of the table the blanks thus move in an orbital path round the cutter and are at the same time rotated on their axes so as to give the correct rolling movement relatively to the cutter to generate the tooth profiles. For this purpose the cutter spindles carry gears 6 engaging idlers which mesh with a fixed internal gear 9. The cutter is reciprocated by an adjustable eccentric 10 connected by a rod 12 with a central rod 11 in the ram. For adjusting the length of stroke, extensions of the eccentric 10 are eccentrically mounted in sleeves 13, 14, Fig. 13, which rotate in bearings 15 so that by rotating the eccentric relatively to the sleeves the two eccentricities may be added or subtracted to give maximum and minimum strokes. The eccentric is driven from a gear 24 mounted on a power shaft 25. The cutter may be vertically adjusted on the ram by releasing a nut 27 and rotating a thrust tube 28 which is fitted with a nut 29 engaging threads on the central rod 11. The cutter is guided during its reciprocation by guides 30 secured to the ram and engaging guideways 30<a>. These guides are straight for cutting straight gears but for shaping helical gears the cutter teeth are of the required helical form and helical guides are arranged to give a twisting movement to the cutter. In this case the ram rotates on the thrust tube 28. The cutter, Fig. 11, consists of a number of cutting portions having teeth of progressively increasing size. The blanks are loaded at a position opposite an untoothed part 37 of the cutter, then pass first on to the lowest cutting portion and then progressively on to larger cutting portions until the teeth are completely generated. The teeth of each different group or series may be formed on one or more than one cutter section, each group preferably containing sufficient teeth of one size to cut completely round the blank during the passage of the blank past the group. In some cases the teeth are continuously graduated round the cutter from the shallowest to the finishing teeth. The cutters are withdrawn from the work on the non-cutting strokes of the ram. For this purpose a tapered sleeve 38 normally forces all the cutters against a ring 39 on the underside of a cover 36 but on the downward stroke the rod 11 and sleeve 38 first move away from the cutter and ram, and compress a spring 40 until it starts the movement of the ram 2. The independent movement of the sleeve 38 causes the cutters to be withdrawn by springs 41. The blank spindles are mounted in holders 42 which are adjustable both circumferentially and radially and which carry tail supports 50 which steady the upper end of the blankspindles. The supports are pivoted at 51 and are normally held in position by a screw 53 passing through a cross piece 52 which may be swung aside to enable the support to be moved about the pivot 51 to give access to the blanks. The table 4 is rotated by a worm wheel 63 driven by a worm 64 on a shaft 65 and connected through bevel gearing 66, reversing bevel gearing 68, change gears 70, and universal shaft 72, with a pinion 74 on the eccentric sleeve 13. The worm shaft 65 is carried in a pivoted bracket so that the worm may be disengaged to permit free rotation of the table.