Patent GB-227505-A (GB)
Title: Improvements in gear cutting machines
IPC: B23F5/14
Filed: 1923-10-12
Abstract: 227,505. Greenwood, E. P., and Green wood, E. Oct. 12, 1923. Gear-cutting; tools.-In a machine for generating gears, a horizontal cutterslide carrying a row of multiple rack-tooth cutters is reciprocated past the blank which has a rotary dividing movement through one or more pitches during the cutting stroke while the cutters are moved through a corresponding distance tangentially of the blank to generate the teeth. The cutters are also fed radially into the work on the cutting stroke and withdrawn on the idle stroke while depth feed of the blank to the cutters is effected after each blank revolution until full tooth depth is reached. A vertical portion 1<1> of the bed carries a vertical slide 4 on which is mounted a horizontal slide 5 reciprocated by pin and slot mechanism from a shaft 6 driven by worm gearing from a main shaft 9. The horizontal slide has a pivoted cutter-carrying clapper 10 which has a lower portion formed with a spherical head 10<2> engaging a block 11 sliding in a member 12 which is moved towards the work on the cutting stroke and quickly withdrawn on the idle stroke by means of a cam 20 acting against a spring 21 and driven from the shaft 6 through gears 22, bevel gears 24 and gears 26. Vertical movement is imparted to the cutterslide during the stroke by means of an adjustable guide 16 mounted on an extension of the framing. In modification, the head 10<2> engages an adjustable guide carried on the member 12 to effect this vertical movement. The blank is carried on a spindle 3 on a saddle and is provided with a dividing wheel 28 driven by a pinion 29 connected by change gears to a wheel on a shaft 31. The latter carries a wheel 32 engaging a vertical rack 33 carried by a lever 34 on a vertical slide 35. The rack is normally pressed into engagement with the wheel 32 by a spring 33<2> and held in this position by a wedge 37<1>. In operation, the rack slide 35 is moved downwardly to effect division by means of a cam 38 on a shaft 39 driven by gears 40 from the shaft 6. At the end of the movement a stop screw 37<2> engages a fixed abutment to withdraw the wedge 37<1> whereupon a second cam 39' swings the lever 34 to withdraw the rack from its gear and permit the rack slide to be returned to its upper by the cam 38. Finally the lever 33' is released by the cam 39<1> and the wedge enters behind the rack to lock it from movement away from its gear. A brake band 43 operated from a hand wheel 44 may be used to lock the blank spindle when required. In a modification of the dividing mechanism the shaft 31 is provided with a ratchet wheel engaged by a pawl plunger operated by a cam on the shaft 39. In order to transmit detpth feeding movement to the work a peg 56 on the dividing wheel engages on each revolution a pawl lever 57 operating a ratchet wheel 59 on a shaft 60 which is connected by bevel gearing and change gears 74 to the feed screw controlling the blank saddle. A wheel 61 on the shaft 60 is geared to a disc 64 carrying a pin operating at each revolution a ratchet-wheel 68 on a loose sleeve surrounding the shaft 60. The ratchet-wheel 68 carries a shield 70 and in operation, when the full depth of cut is reached the shield 70 passes under the pawl of the lever 57 and prevents further rotation of the wheel 59 thus stopping the feed. The cutter slide may carry a stocking-cutter arranged in front of the generating rack-cutters and instead of the gradual feed of the cutters during the stroke the cutter box may be set at angle, the cutters being arranged so that the teeth are finished parallel. In a modification, Fig. 11, cutters of quadrant form may be substituted for the rack cutters and these are moved through a vertical arc during the rotation of the blank by means of rack and pinion mechanism 51 operated from an inclined guide bar.