GB199462A - Improvements in machines for generating the teeth of gear wheels - Google Patents

Abstract

199,462. Soc. Anon. des Anciens Etablissements Hotchkiss et Cie, and Taylor, H. E. March 22, 1922. Gear-cutting.-Gears are generated according to the " tangent, rack " system wherein instead of the usual linear rack, the basic form is a crown wheel whose teeth are involute curves in a plane normal to the wheel axis. The normal pitch thickness of tooth. and space is constant thus permitting the generating of two adjacent tooth faces by means of a single tool whose cutting plane is maintained normal to the sides of the teeth. The wheel blank is mounted and actuated so as to roll as though in engagement with the basic crown wheel while the tool traces out a curved path corresponding to one tooth of the crown wheel, the tool path being derived from an angular movement about the imaginary crown wheel axis combined with a movement tangential to a circle of adjustable radius. In this manner the cutting plane of the tool is kept normal to the sides of the teeth which it generates. The blank A is mounted on an arbor B in a work head C which is movable about the axis 0-0 of the imaginary basic crown gear, the angle X being adjustable according to the gear to be cut. The motion about the axis 0-0 is derived from worm and sector gearing C<3> driven through change gears, shaft E and bevel gearing operated by ratchet and pawl mechanism from a shaft G which is oscillated by means of a cam 0 from the main shaft N. The shaft E is operatively connected to the gear blank arbor through bevel gearing, telescopic shaft H<3> and worm gearing, this movement together with the movement about the axis 0-0 producing correct rolling of the blank. The rack-tooth tool K is mounted on a slide J<2> carried by an oscillating member J on a shaft L oscillated by means of a rack M which is reciprocated by a crank from the main shaft. A rack J<3> on the tool slide engages a pinion J<4> connected to a pinion J<6> fixed to the member J so that as the latter oscillates the slide J<2> is reciprocated to impart the required curved path to the tool as shown in Fig. 4. In order to withdraw the tool from the work on the return stroke the bearings of the shaft L are mounted in a headstock L<3> engaged by a quick pitch screw P actuated by a cam P<4> and lever P<2> to withdraw the headstock on the return stroke along guides D<@>. For cutting wheels whose axes do not intersect the axis of the imaginary crown gear a cross slide may be provided for laterally displacing the respective axes about which the head C and member J move. Specification 199,463 is referred to.