ABSTRACT

Various numerical methods have been suggested for validation of tooth root bending strength. In these approaches, it has always been a challenge to consider local strength – as determined by hardness and residual stresses – in numerical calculations. Therefore, the analytical approaches as described in standards such as ISO 6336-3 prevail in gear rating. This standard, however, does not consider typical or even less typical deviations or variants in the actual tooth root geometry.

Geometrical deviations in the form of grinding notches occur due to lack of or insufficient protuberance. In this case, the individual result may have little, moderate or even a significant negative impact on the bending strength. Tooth root geometry may also be different from the shape as described in ISO 6336-3 as generated by form grinding or 5-axes-milling.

If carried out with caution, these variants obviously do not cause a significant loss in load carrying capacity but are not fully covered by the analytic calculation methods. The presented approach for external cylindrical gears combines the well-established ISO 6336-3 method with a numerical add-on to identify and consider the additional influence of the actual tooth root geometry. The additional stress concentration in the area of the 30-degree tangent is described as a reduction of safety against tooth root breakage.

Author(s): Burkhard Pinnekamp, Michael Heider, Andreas Beinstingel, Maximilian Fromberger, Michael Keller

ISBN: 978-1-64353-166-3