Patent GB-437365-A (GB)
Title: Improvements in or relating to gear cutters and sharpening apparatus therefor
IPC: B23F21/10
Filed: 1934-03-29
Abstract: 437,365. Grinding gear-cutting tools. McLEOD, R. J., c/o Power Plant Co., West Drayton, Middlesex. March 29, 1934, No. 9907. [Class 60] [See also Group XXII] In a helically-toothed pinion cutter 11 for cutting gears, the teeth are ground with a hollow face 15 to provide a cutting-edge on the " obtuse " edge 13 and ground with a bevel on the " acute " edge 14 in such a way that both cutting edges have correct cutting angles and lie in a plane at right angles to the cutter axis.' The projection beyond the cutting-edges of the edge 16 lying in the original end face of the cutter is thus kept small so that no interference occurs when herring-bone teeth are cut. For grinding the cutter, the base plate 20 of a grinding-machine attachment carries a slide 27, Fig. 3, operated by a pivoted lever 28 in a direction parallel to the spindle of the grinding- wheel 22. A plate 47 is pivoted to the slide on a pin 23 and its inclination relatively to the slide is adjustable by screws 48, 49. The carrier plate carries a rotatable work plate 32, on which the cutter is mounted concentrically with the rotational axis 31. The cutter is indexed by means of a pivoted arm 33 carrying a conical roller 35. The base plate is fitted with side grooves 36, 37, one of which carries a bracket 39 fitted with an adjustable eye block 41 which receives a rod 42 secured to the work plate. In operation, as the slide 26 is traversed to move the work beneath the grinding wheel, the rod 42 imparts a rotation to the work plate which is governed by a radius of varying length thus causing the tooth 12 to follow relatively to the grinding wheel, an approximately involute path. The inclination of the plate 47 causes gradual deepening of the hollow face from tip to root. For grinding the acute edges, the bracket 39 is moved over to the slot 37, and the work reset by means of the roller 35 and the operation repeated. In a modification, Fig. 4, the base plate 50 carries a slide 51 reciprocated by a lever 52 or automatically and carrying a plate 54 pivoted at 53 and adjustable by a screw 55. The cutter is mounted with an index plate and roller 60 on a pin 57 carried by the plate 54. A spring stop 63 secures the work in indexed positions. Supports 65 pivoted on either side of the plate 54 are tilted by screws 67 correspondingly to the plate 54 and either support may carry a plane control plate 68 engaging the roller 60. In this form, as the slide 51 is reciprocated the roller 60 rolls on the control plate to impart the required angular movement to the work. After grinding the obtuse edges, the control plate is placed on the opposite side of the roller 60 for grinding the acute edges. The usual lateral and vertical adjustments for the grinding wheel may be provided. In some cases a spherical or other curved-edge grinding-wheel may be located as shown in Fig. 8. The acute edges may also be ground by a wheel located as in Fig. 11 or by the peripheral surface of such a wheel. A method of calculating the angular movement to be imparted to the work by the rod 42 or roller 60 is described in the Specification.