GB331973A - An improved method and apparatus for producing cylindrical gears - Google Patents

Abstract

331,973. Mammano, B. May 3. 1929. Gear-cutting; milling-cutters. - A number of toothed wheels or racks are generated simultaneously by means of tools which rotate round a fixed axis, the individual tools engaging successive teeth on continuously rotating gear blanks which have their axis parallel to the plane of movement, of the tools. In Fig. 2 four tools I - - IV rotating round a fixed axis 0 are shown in operative relation with four gear blanks which rotate in the direction of the arrows f<1> - - f<4> at speeds such that while a particular tool 1 in moving from 1 to 1<11> traces out a curve S<11> on a gear blank. After a tool head rotation of 90‹ the tool IV reaches position 1 and cuts the next successive space on the blank. Any other number of tools may be employed and any convenient number of blanks may be cut simultaneously. In some cases the tool head may be fitted with tools on both sides and the gears R may be of different. sizes as shown in Figs. 5 and 6 provided that in each case the ratio of the angular speed of the blank to the angular speed of the tool is equal to the ratio between the number of tools and the number of teeth to be cut. In order to generate the tooth surfaces the blank axis is translated in a plane parallel to the plane of movement of the tools and corresponding rotary movement is superposed on the blank rotation by means of a differential gear or similar mechanism. For roughing gears the generating movements may be dispensed with and the gears may be located as shown in Fig. 6. Instead of single tools X, Y, V, W engaging in successive tooth spaces on a blank, a number of auxiliary tools may be arranged along a spiral V1, V, V2, Fig. 8, to operate in the same tooth space as the tool V. The tools W, X and Y may be similarly supplemented by additional tools arranged along spiral curves. Some of the tools may be adapted forroughing and others for finishing operations, or, in some cases, successive tools may operate on alternate sides of the tooth space. In another modification, Fig. 9, milling tools M or grinding wheels may be employed, these tools being rotated on their own axes in addition to the planetary movement about the central axis 0. In another modification, Fig. 11, pointed tools I may be, employed, these tools being fixed to a tool disc D rotating round a, central axis Z. In order to shape the whole flanks of the teeth such tools are moved relatively to the gear blank along a line such as e, f, or, for cutting cycloidal gears, the. line of movement, of the tool point may be along a cycloidal curve.Preferably the tool disc is kept stationary and the movement in the direction e, f is imparted to the gear blank. Any particular gear blank may be positioned or removed on completion without stopping themachine and automatic means may be provided for slowly advancing the gear blank to the working position and withdrawing the gear rapidly on completion of the operation.