Multi-contact in modified helical gear tooth pair considering misalignments

Abstract

Tooth modification is an effective method for reducing the undesirable effects introduced by misalignments, but the magnitude of such modifications with respect to any given misalignments is uncertain and largely based on experience. A mathematical model of a helical gear pair is established to study the coupling effects of tooth modifications and misalignments on the system's multi-contact behavior. Misalignments are defined as the deviations of the ends of axes in gear and pinion mechanisms from their ideal positions, and they affect the contact behavior through transformation matrices. Deformations in the gear and pinion are computed by a finite element method. Misalignments, tooth modifications, and the gear's deformation influence the contact behavior by altering the distances between contact lines at corresponding contact tooth pairs. The actual contact is believed to occur at the contact line section(s) with the smallest distance. Using the proposed model, the influences of misalignments, tooth modifications, and their couplings on the contact load distribution, contact load share ratio, and contact load deviation factor are analyzed. The results show that an optimum tooth modification does exist for helical gear pairs under a given external load and misalignments.