Patent GB-435702-A (GB)
Title: Gear shaping machine
IPC: B23F23/12
Filed: 1934-03-23
Abstract: 435,702. Gear - cutting. MILLER, E. W., 9, Elm Street, Springfield, and FELLOWS GEAR SHAPER CO., Springfield, Vermont, U.S.A. March 23, 1934, No. 9130. [Class 83 (iii)] A gear-generating machine having a reciprocating pinion cutter 26 which is rotated in unison with the work to generate the teeth is provided with a work-spindle 21 having means for longitudinal adjustment. The cutterspindle 25 is mounted in a carriage 22 movable transversely of the work-spindle along guides 23, 24. The cutter-spindle is reciprocated by a gear segment 30 engaging a circular rack 28 and operated from an adjustable crank disc 34 through a link 31. The crank disc is driven from an eleetric motor 36 through belt gearing. Generating movement is imparted to the cutter-spindle by means of a worm-wheel 40 coacting with a worm 41 on a shaft 42 driven from the main shaft 33 through gearing including a shaft 50, Fig. 6, clutch 51, shaft 52 reversing bevel gearing 55, shaft 56, gearing 57 and clutch 59. The sleeve 60 carrying the reversing-bevels is operated from a hand crank. The work-piece is mounted on an arbor secured in the spindle 21 which is rotated in unison with the cutter by a gear train driven by the shaft 52 and including change gears 66, shaft 65, bevel gears 70, vertical shaft 72, 74, reversing bevel gearing 75 operated by a rod 80, and shaft 78 carrying a worm 88 engaging a worm wheel 90a on the work-spindle. Another shaft 82 driven in unison with the shaft 78 carries a worm 89, Fig. 17, engaging the opposite side of the worm wheel 90a. Spring-tensioning means act on the worm 89 to take up backlash, such means consisting of springs 96, 97, Fig. 17, acting through thrust bearings, an adjusting shaft 103 being provided by which one or other of the springs may be arranged to act on the worm 89 according to the direction of rotation. The cutter carriage is movable along its guides for depth feed and withdrawal of the cutter, the worm 41 being movable along its shaft for this purpose. These movements are effected by a depth feed cam 105. The carriage is adjusted relatively to the cam by a pinion 108 coacting with the rack bar 106, and is yieldingly urged towards the cam by a pinion 113 acted upon by a fluid pressure cylinder or by a weight. The depth feed cam is rotated from the shaft 65 through a gear 123 which drives a shaft connected by worm gearing 126 to the shaft 130 carrying the feed cam. The cam may also be turned by hand. After each cutting stroke the cutter carriage is slightly withdrawn from the work to relieve the cutter and at the same time the spindle is given a slight angular movement about its axis to avoid interference with the work consequent upon the rectilinear relieving movement. The translative movement is effected by bodily movement of the feed cam, which is mounted in a frame pivoted at 137 and moved about the pivot by a cam 138 on the main shaft 33. The angular component of the relief movement is effected by giving the worm wheel 40 an angular movement by means of a spring which urges the worm 41 against a lever 145 controlled by a cam 141 which is driven by a train of gearing from the shaft 33, timed so that the cutter is oscillated away from the work at the end of the stroke and returned before the next working stroke. The cam 141 may also be arranged to impart a slight progressive angular movement to the cutter during the working stroke, a slow rise a, b, Fig. 6a, being formed on the cam for this purpose in front of the part b, c of the cam for producing the relieving motion. Thus helical motion of the cutter may be caused to supplement the effect of helical guides in cutting helical gears so that gears of greater or less helical angle than the guides may be made. It may also be used, in cutting either straight or helical gears to compensate for subsequent warping of a gear during heat treatment. The translation relieving-cam 138 may also be arranged to vary the centre distances between work and cutter axis during the stroke so as to produce a crowned tooth form, Fig. 3b, on the gear 261, such a form giving quieter running gears and compensating for slight errors in alignment. The work-spindle 21a, Fig. 4, is longitudinally adjustable in a bearing 159 by means of a pinion engaging in a circular rack 160, and an interchangeable supplementary bearing may be used to support the upper part of the spindle. In a modification of the spindle mounting, Fig. 1, the spindle and its quill are removed and substituted when required and the lower end of the spindle is carried in a bearing 171. In another modification, the work spindle with its driving worm and worm wheel &c. is mounted in bearings in a sliding frame movable in guideways on the frame by rack-and-pinion gearing. For cutting helical gears, the cutterspindle is guided by helical guides. A sleeve 187, Fig. 19, on the cutter-spindle has a number of ribs 188 of the required helical angle and a complemental guide sleeve 189 is secured within the wheel 40. The complemental ribs are cast in Babbitt or similar metal around the sleeve 188 after the parts are assembled. A supplemental sleeve 191 is located above the sleeve 189 and is angularly adjustable to take up backlash in the cutter-spindle guiding mechanism.