Patent GB-772237-A (GB)
Title: Improvements relating to machines and methods for generating gears
IPC: B23F5/20
Filed: 1954-07-30
Abstract: 772,237. Gear-cutting. GLEASON WORKS. July 30, 1954 [Aug. 6, 1953], No. 22367/54. Class 83 (3). [Also in Group XXXIV] A machine for generating gears in which the work and tool are rolled relatively to one another, comprises means 106 for providing a dwell between the beginning and mid-point of a generating roll in one direction, and means 113 to feed the tool and work relatively into nearly full depth position and to complete the feed movement at the end of the roll. The work-spindle 27 is mounted in a head 25 adjustable axially of the spindle on a base 23 swinging on a slide 21. A cutter-cradle 28 is rotatable about an axis 29 intersecting the axis of the spindle 27. Each of two cutter-heads 38 is adjustable by a screw 42 towards the axis 29 on a slide 34, which is adjustable transversely by a screw 36 on an angularly-adjustable plate 31. The plates 31 are adjusted by a turnbuckle 33 and clamped by screws 32. The cutters 45 have inter-spaced teeth 46, and are rotated by a motor 47 through change-speed gears 49. At least one cutter is adjustable angularly on its spindle to allow for tooth-inter-spacing adjustment after cutter-head adjustment. To this end, the cutter is keyed to its spindle by a block 65 having an eccentric opening 66. By removing the cutter and turning the block by one or more quarter-turns, the necessary adjustment is made. Substantially only one blade engages the work at a time. To avoid chatter, therefore, a gear 62 on the cutter-spindle contains annular brake-shoes 71 pressed outwardly by springs 73 and held from rotation by a key 75. After chucking a workpiece, the slide 21 is moved forward by admitting fluid to a cylinder 118, in which is mounted a piston on a rod 121 adjustably-mounted on the slide at 120. The cylinder 118 is movable axially under the control of a lever 115 bearing a follower 114 engaging a track 113 in a cam-drum 102. The drum is rotated by the motor 47 through rate-of-roll changegears 103. The drum also has a track 106 engaged by a follower 107 on a segment 108 which rotates the cradle 99 through angle-ofroll change-gears 112 and rotates the workspindle 27 through ratio-of-roll change-gears 94 and index change-gears 79. The work is indexed through a Geneva-type mechanism 124, 134. The member 124 is rotated three times for each rotation of the cam 102, but is operative only on the third turn when it is moved into engagement with the member 134 by a yoke 148 moved by link 149, levers 146, 145, and a follower 142 in a third track 141 in the cam 102. The parts of the Geneva-mechanism are completely disengaged except when the shaft 135 is being turned. The shaft is held stationary between indexing movements by a dog 153 engaging a disc 154 on an adjacent shaft 101. The dog 153 is carried on a lever 155 operated by a roller 156, held in engagement with a camsurface 157, by a lever 159 carrying a spring 161 and a roller 162 engaging a second cam-surface 163. The rollers 156, 162 coincide with their cams only when the member 124 has been moved to its operative position. The machine is automatically stopped when a gear is completely cut with the cradle at the top of its uproll (the limit of counter-clockwise movement in Fig. 3), so that initially the cams 106, 113, 141 are engaged by their followers at the line 165, Fig. 12. In operation, a valve-lever 123 is moved to advance the work to the cutters by the piston 119, the motor 47 is started, and the track 141 swings the lever 146 to bring the Genevamechanism into operative position. The track 113 moves the head 25 away from the cutters and the track 106 starts the cradle down-roll movement (clockwise in Fig. 3). At position 167, Fig. 12, indexing is complete, track 106 causes a dwell in the down-roll, track 141 withdraws the Geneva-mechanism, and track 113 starts an infeed of the work. The cutter-teeth are then in the position 46<SP>1</SP> on line 170, Fig. 13, intermediate their upper-position 168 and centre-position 169. This position 170 occurs when the down-roll is 30 per cent complete for straight-toothed bevel-gears. Feed of the gear by the track 113 then continues to line 174, Fig. 12, so that the cutter-teeth occupy the position 46, Fig. 13, relatively to the space 171 to be finished. At this stage, the track 106 recommences the down-roll which continues to line 177, Fig. 12, at which time there is a fairly constant and narrow band of material left to remove from the tooth-space 171, Fig. 14. The track 113 now moves the gear to full depth, the teeth then being in position 46<SP>1</SP>, Fig. 14. Uproll of the cradle is then completed and the cycle restarts at line 165. In a modification, the movement to full-depth is made by movement of a second piston of adjustable stroke, indicated by a scale, in the end of the cylinder 118, Fig. 4, so that the piston 119 moves further to the right. Movement of the second piston is controlled by a cam-track in an end-surface of the cam 102. Except when cutting bevel-gears with skew teeth, the tool-heads are symmetrical on the cradle. Specification 772,238 is referred to.