An exact system of generation for face-hobbed hypoid gears: Application to high reduction hypoid gear drives

Abstract

The determination of the pitch cones for hypoid gears is already well defined either through numerical methods as those shown in the Standard ANSI/AGMA ISO 23509-B17 or through algorithms available in the specialized literature. However, a procedure to determine the gear tooth surfaces for hypoid gears directly from their pitch cones is still missing. An analytical approach to determine the basic machine-tool settings for the pinion and the wheel of hypoid gear drives is proposed here. It is based on the condition of exact generation, which means that the gears will operate under conjugate condition. It can be applied for generation of face-hobbed hypoid gears, produced either by the CycloCut or the CycloPalloid generation methods. A numerical example proves the goodness of the proposed methodology in a high reduction hypoid gear drive. The results of tooth contact and stress analyses prove that the bearing contact is localized and stable against misalignments, requiring just a small adjustment through the application of an optimum tip relief to the gear tooth surfaces to minimize the maximum contact pressure.