Patent GB-543408-A (GB)
Title: Improvements in gear cutting machines
IPC: B23F9/10
Filed: 1940-10-18
Abstract: 543,408. Gear-cutting. GLEASON WORKS. Oct. 18, 1940, No. 15446. Convention date, Nov. 24, 1939. [Class 83 (iii)] A machine for generating longitudinally curved tooth tapered gears having a face-mill gear cutter has means to vary the ratio of the relative rolling movement between the gear and blank during the progress of said movement. This variable ratio of roll enables spiral bevels or hypoids intended to gear with form-cut mating gears and having the desired tooth bearing and pressure angle to be cut on a machine having the cutter spindle parallel to the cradle axis. The base 20 is fitted with a full circular cutter cradle 21 having a central axis Y, Fig. 2, and mounted on roller bearings 24. A cutter carrier 25 is mounted to rotate in the cradle about an eccentric axis X, and carries a face-milling cutter C mounted on a spindle 30 eccentrically located in the carrier. The cutter is continuously driven from a motor 35, Fig. 13, through bevel gearing 36, spur gearing 39, bevel gears 43, spur gears 50, bevel gears 54, and spiral bevel gears 60, 61 the latter being secured to a fly-wheel member 63. The shaft 44 coincides with the axis Y of the cradle and the shaft 52 with the axis X of the carrier so that the rotary adjustments of the cradle and carrier to position the cutter spindle for cutting different gears do not affect the cutter drive. These adjustments are facilitated by circular scales provided on the cradle and cutter carrier respectively. The spindle 75 of the gear blank G is mounted in a head 76 which is vertically adjustable, for obtaining an offset work axis for cutting hypoid gears, on a column 77 which is adjustable on a plate 85 to set the blank to the required cone distance. The plate 85 is angularly adjustable about the axis P to set the blank to the required cone angle and is carried by a sliding base 90 which is movable on ways 95 in the direction of the cradle axis to apply depth feed of the work to the cutter. The work spindle is driven from the motor 35, Fig. 13, through a train including spur gearing 103, shaft 105, clutch 116, reversing gearing 111, 113, spur gearing 118, 121, shaft 123, change gears 128, differential gear 131, shaft 135, bevel gears 136, 139, 142, 146, index change gears 150, and worm gearing 154. The clutch 116 may be disengaged for hand adjustment of the cutter from a hand-wheel 163. The cradle drive in unison with the work rotation is obtained from the shaft 123 through bevel gearing 161 and worm gearing 164. The variation of the rolling ratio during the progress of the operation is effected by imparting axial movement to the worm 164. For this purpose a branch train 170, 176 from the worm shaft 162 drives a worm wheel 181 mounted on a shaft 182 which may be locked to the worm wheel in either of two positions by a pin 187. The head of the shaft 182 carries a radially adjustable block 200 fitted with a roller 203 engaging a piston 204 connected through bearings 208 with the worm shaft 162. The motion of the cradle is thus accelerated or retarded according to the direction of movement of the worm shaft. The direction of movement may be altered by adjusting the shaft 182 in the worm wheel 181, one direction being used normally for cutting the concave faces and the other for the convex faces of the teeth. The piston 204 is held up to the roller 203 by hydraulic fluid controlled by a valve. In one position of the valve fluid is supplied to a port 234 to cause the piston to follow the roller. In the other position the piston is moved away from the roller which can then be adjusted as required. When the cradle and work have completed a generating roll in one direction, the reverse mechanism of the machine is tripped to reverse the drive. The work is then withdrawn by a cam 260 and indexed. This cam, Fig. 9, is driven by a worm gearing 263 from the shaft 109 and has two tracks engageable selectively with rollers 267, 268 moved alternatively into position by a pinion 287 engaging racks on the roller carriers. One track is used for roughing and the other for finishing operations. The rollers are carried by a lever which is adjustably connected to a cylinder block 300, the piston rod 305 of which is adjustably connected to the base 90. In normal operation the piston is held by fluid pressure against the right-hand end, Fig. 9, of the cylinder and the cam 260 moves the blank in and out of cutting engagement with the tool. During the withdrawal period the blank is indexed by Geneva mechanism 277 operated from the shaft 109 and acting on the housing of the differential gearing 130. When all the teeth have been cut the base 90 is moved to a loading position by moving the piston to the left-hand end of cylinder 300. Any change in height of the cutting blades is compensated by adjustment of the piston rod 305 in the block.