A novel ease-off flank modification methodology for spiral bevel and hypoid gears

Gear flank modification is an important technique for reducing gear running noise and avoiding edge contact for spiral bevel and hypoid gears. This work proposes a novel ease-off flank modification methodology for spiral bevel and hypoid gears made by a modern Cartesian-type hypoid gear generator. The first step is to obtain the desired ease-off topography by calculating and then synthesizing the ease-off along the contact path from the predesigned transmission error and along the contact line from the predesigned bearing ratio. The second step establishes the ease-off sensitivity matrix that corresponds to the pinion head cutter and the six-axis motion parameters of a hypoid generator based on a mathematical model of a modern Cartesian hypoid generator. Finally, linear regression identifies the corrective machine settings for modifying the pinion tooth flanks so that they approximate the desired ease-off topography. We demonstrate the validity of this flank modification method using a numerical example of the Gleason Triac face-hobbed hypoid gear made by a Cartesian-type CNC machine. This proposed flank modification methodology can serve as a basis for developing a general technique of flank modification for other gear types.