Practical formula for true root stress of WN gear tooth. Haseg SymMarC gear.

A method for calculating the tooth profile of a WN (SymMarC) gear generated with a hob was indicated and a mapping function for the profile approximated to the tooth profile of a WN gear was obtained. The true root stresses of a WN gear calculated by 2-dimensional elasticity theory and mapping function were compared with those obtained by the 2-dimensional finite element method (FEM), and the validity of the root stress analysis of a WN gear by the theory of elasticity was confirmed, and the position of the critical section on the tensile and compressive sides of a WN gear was indicated. The stress concentration factors at the position of the critical section were calculated under different loading conditions. A practical formula for true root stress of a WN gear was derived on the basis of these calculated results.