Patent ID: 9221113
Filing Date: 2015-12-29
Classification: B23F,Y10T

Abstract:
1. A method of generating teeth of a double involute pinion on a conventional hobbing machine that mesh with face gear teeth of a double involute pinion-face gear drive system, comprising the steps of: providing a double involute pinion blank, of cylindrical shape, having a blank face width center plane and a blank axis perpendicular to said blank face width center plane, that rotates continuously about said blank axis, providing a face hob tool having a tool axis and a tool pitch plane perpendicular to said tool axis within which a tool base circle identical to the teeth base circle of radius rb of said face gear is defined, including a plurality of equi-spaced rack cutters, with cutting teeth of symmetrical or asymmetrical type projecting from one plane face of said face hob tool body in a direction of said tool axis and arranged such that lines of intersection between said tool pitch plane and rake surfaces of said cutting teeth are tangent to a tool circle concentric to said tool base circle, positioning said face hob tool offset from and perpendicular to said blank axis at a predetermined center distance of said double involute pinion-face gear drive system, such that a teeth width middle section plane of said double involute pinion blank is tangent to said tool base circle and, at a start machining position, said face hob tool is adjacent but not in generating engagement with said double involute pinion blank, rotating said face hob tool continuously about said tool axis in timed relation with said continuous rotation of said double involute pinion blank about said blank axis, while simultaneously and continuously radially feeding said face hob tool toward an outer peripheral cylindrical surface of said double involute pinion blank along the direction of said tool axis and into generating engagement with said double involute pinion blank, whereby said face hob tool, of modified involute type, is specifically designed such that a concentric circle of said face hob tool has its radius equal to either (rb+p) or (rb−p) where p is the amount of involute modification of said face gear teeth, generates double involute external teeth of constant height and circular pitch, of symmetrical or asymmetrical type, on an outer cylindrical surface of said double involute pinion blank, shaped in form of a normal involute in their profile direction and curved in their longitudinal direction in form of an either shortened or an extended involute curve of said face gear base circle, respectively.