Patent GB-548225-A (GB)
Title: Machine for generating and cutting gears, sprockets, cams and similar articles
IPC: B23F5/12
Filed: 1941-03-26
Abstract: 548,225. Gear cutting. MILLER, E. W., and FELLOWS GEAR SHAPER CO. March 26, 1941, No. 4082. [Class 83 (iii)] In a machine for generating helical or spur gears, sprockets, cams and the like, mechanism operated in timed relation with cutting and rolling-generating movements is provided for clamping successive work pieces on the work spindle and releasing them therefrom. The work W, either a series of discs (as shown) or a single solid gear, is mounted on vertical arbor 1 supported in a work spindle 3 rotating in a sleeve 4, the upper end of the arbor being centred by a support 6 bearing in an arm 7. The elongated rack-cutter C is secured to a head 8 secured to a slide 9 movable in a holder 11 pivoted on a plate 13. The cutter may be arranged to follow either a vertical or inclined path. The weight of the slide is counterbalanced by a spring 15. The cutter is reciprocated from a motor 19 through belt gearing 22, spindle 20, crank 24, rack rod 25 and rock shaft 28 carrying a gear 30 engaging a rack 31 on the slide 9. In order to set the cutter at the required helical angle the plate 13 has a sleeve portion 32 engaging a bearing 33 and forming a bearing for the shaft 28. The cutter head is also tilted on its slide in order to maintain the cutting plane perpendicular to the work axis, Fig. 6a. Relief of the cutter is effected by a cam 39, Fig. 5, acting through a bell-crank 40 and push-rod 41 which forces the cutter holder outwardly against stop shoulders during the cutting strokes and allows a spring 46 to retract the cutter on the return strokes. The cutter carriage may be adjusted by a micrometer head 51 to set the cutter radially of the work axis. In order to generate the teeth the cutter is moved tangentially while the work is rotated in unison. For the tangential movement the cutter-slide 47 is guided over rollers 54, 55 by a rib 56 embraced by two pairs of rollers 57. Upward movement of the slide during cutting is prevented by a roller 58. The drive for the generating movements is derived from a motor 62 chain-geared to a shaft 66 coupled by a clutch 67 to a shaft 69 connected through change gears 71 with a worm wheel 74 on the work spindle. A shaft 72 of this train is geared to a screwed shaft 80 actuating a carriage 82 carrying an angularly adjustable cam-bar 83, engaged by an abutment 84 on the slide 47. By angular adjustments of the bar 83 variable tangential movements may be imparted to the cutter. In a modification, the cam bar is replaced by an involute cam 96, Fig. 20, coacting with an abutment 97 pivoted by a stud 98 to the slide 47. The tangential carriage-movement may be altered by rotating the abutment about its pivot to alter the inclination of its face to the direction of carriage movement. The cam 96 is mounted on a spindle driven from a motor through change gears, clutch 67, shaft 72 and further gearing. In a further modification, Fig. 28, the cutter carriage is moved tangentially by a screw 80a driven through a change-gear train 120 from the shaft 72b which also drives the work spindle. As the slide travels a bell-crank 124 having one arm guided in an adjustable wedge-bar imparts variable axial movement to the screw 80a, Fig. 29, thus giving an incremental movement to the slide additional to that imparted by rotation of the screw and giving fine gradations of the range of tangential generating movements. In another modification of the means for imparting axial movement to the screw 80a an adjustable cam-bar 130a, Fig 30, actuates a rack 139 connected by pinion 142 to an auxiliary slide 144 in which the screw 80a rotates. In another modification the incremental movement is imparted to the screw 80a itself through differential gearing. The machine is particularly suitable for cutting small pinions from 1/16 inch to 1 inch in diameter. Automatic means are provided for supplying blanks from a magazine and eject- 'ing the finished work-pieces. In one form, Figs. 15 and 17, the blanks in the form of thin discs are strung on an arbor 1 over a base flange 166 and pin 167. A number of these assemblies are carried in a two-part magazine 168 mounted in a holder 173. A pusher 176 connected to a spring metal tape 178 urges the blanks towards a retainer 181 having hooks engaging the arbor 1 of the end assembly. Different magazines may be mounted interchangeably in holder 173 which is mounted on a splined shaft 187 which is partially rotated to bring the outermost blank into alignment with the work spindle. An ejector 189, Fig. 22, is operated by a cam 199, and the arm 7 which carries the upper arbor support is mounted on a shaft 193 operated by a second cam on a shaft 201 driven from the feed motor 62 through one-way ratchet clutches arranged to impart a unidirectional drive to a shaft 214, notwithstanding reversal of the motor 62, so that the machine may cut in both directions of cutter traverse. The ejector 189 and the arbor support 6 are operated in unison with the magazine movements to release a completed blank and pick off the blank presented by the magazine. The shaft 214 is connectible to the cam shaft by a clutch 215. The steps of the cutting cycle are controlled by actuation of the clutches 67, 215, through a solenoid 222 under control of the cam-bar carriage 82. The solenoid core is connected by lever mechanism to a rock shaft 229 which also carries a fork, Fig. 7, operating the clutch 67 which is normally engaged when the solenoid is inactive. The clutch 215 is normally held disengaged by a stop lever 233, Fig. 7, engaging an abutment 236. When the solenoid is energized lever 225 is lowered, thus allowing clutch 215 to engage and disengaging the clutch 67 to stop the generating motions. In some cases the cutter may have an inoperative return after completing a gear. Various other adapters and arbor supports for accommodating different blanks are described in the Specification. The machine operates without depth feed, the cutter being adjusted to the required radial position and having at least as many teeth as are to be cut in the blank so that a gear is completely generated by a tangential traverse of the cutter from a position clear of the blank on one side to a similar position on the other side.