A theoretical model of time-varying meshing stiffness for a spur-face gear drive according to its localized characteristics during point-contact

The contact region is actually an ellipse during point-contact, as stated by Hertzian contact theory. The load in the contact ellipse (CE) gradually decays rather than uniformly distributes due to the varying curvature of contact surfaces. Spur-face gear drive (SFGD) is highly valued in modern machines due to its point-contact characteristics. An improved theoretical model of time-varying mesh stiffness (TVMS) for SFGD has been constructed by coupling tooth, contact and fillet-foundation stiffness. A novel thought named deformation suppression which there is a fixed effect on the CE by the area outside the CE due to the absence of force is proposed according to the local contact characteristics of point-contact. The coupling effect between the meshing teeth pairs and the fillet-foundation stiffness are both considered. The position, size and incompleteness of the CE are determined by the movement of the meshing tracks which are derived from the explicit equation and multi-state meshing regions of SFGD and the load distribution ratio (LDR) calculated based on them. The characteristics of point contact are qualitatively verified experimentally. The results show that LDR mutations of gear switching are reduced considering incomplete CE. TVMS of point-contact considering deformation suppression is improved by an order of magnitude compared to the one of line-contact which may be the cause for the high carrying capacity of point-contact. It can be the basis to investigate the characteristics of SFGD and the point-contact further. This method is applicable to the study of point-contact in other fields.