Method for the pre-dimensioning of beveloid gears

Abstract

Conical involute gears – also referred to as beveloid gears – are based on cylindrical involute gears, as both gear geometries are based on a basic rack. They differ from cylindrical gears in that the beveloid gears’ addendum modification along the face width is not constant, but linearly variable. This allows beveloid gears to transfer mechanical power with parallel, intersecting or even skewed axes up to shaft angles of approximately 20°, whereas bevel or hypoid gears are applied with larger shaft angles. Compared with both cylindrical and bevel gears, there is less knowledge available concerning the design of beveloid gears. Existing tools for contact analysis are based on predetermined main gearing data. Therefore a method to pre-dimension main beveloid gearing data based on application requirements was developed. Initially, equivalent cylindrical gears are dimensioned and then transformed into beveloid gears with the required mounting positions. The method involves pre-optimizing of beveloid gears with several targets. Firstly, to comply with selected boundaries of the addendum modification coefficient, as well as to minimize ease-off between the tooth flanks achieved by a centric contact pattern and ensure adequate tip clearance by reducing tip circles. The method was implemented in a software environment for tooth contact analysis and applied to a wide range of data sets. The evaluation demonstrated the efficient design of the main data of beveloid gears including pre-optimization to achieve the objectives mentioned previously. In further optimizations, the microgeometry of beveloid gears must be adapted regarding the gap that occurs between the flanks.