GB206171A - Improved method of and apparatus for generating the teeth of toothed gears - Google Patents

Abstract

206,171. Lewis, F. M. April 21, 1922. Gear-cutting; tools.-The teeth of straight or helical spur or bevel gears are generated by a process in which the blank is rotated when the generating movement between the cutter and the blank is substantially radial instead of as usual tangential to the blank. By this method indexing of the blank is eliminated. The blank a, Fig. 1, is carried on a spindle which is mounted on a slide k and which carries a worm wheel g driven through gearing from a wheel c on a shaft provided with a cam h co-operating with a fixed roller i. The radial feed and rotation of the blank are simultaneously operated by means of a ratchet rack n reciprocated by a pneumatic cylinder l driven from the power shaft which drives the reciprocating cutter b. The latter, which may be of substantially rack form, is positioned so that the gap between two cutting teeth is disposed radially of the blank, the cam h being so arranged that a complete radial generating reciprocation takes place while the blank rotates through one pitch. Alternative constructions for the cam wheel and ratchet drive are described and the generating reciprocatory movements may be imparted to the cutter instead of to the blank. For cutting bevel wheels the blank a<1>, Fig. 5, and cam wheel h<1> are mounted on a plate k<1> which is pivoted at a point k<2> approximately coinciding with the blank cone apex. In the application of the invention to helical gears either spur or bevel, a differential mechanism may connect the crossfeed of the blank and its rotation. According to the Provisional Specification the generated teeth are of involute form.