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Advances in Tribology
Volume 2018, Article ID 9607092, 8 pages
https://doi.org/10.1155/2018/9607092
Research Article

The Contact Mechanics of Novikov’s Surface-Hardened Gearing during Running-in Process

1Department of Transport, Construction and Road System, Don State Technical University, Rostov-on-Don 344000, Russia
2Institute of Mathematics, Mechanics and Computer Science, South Federal University, Rostov-on-Don 344006, Russia

Correspondence should be addressed to Alexey Beskopylny; ur.xednay@na-kseb

Received 28 May 2018; Revised 11 August 2018; Accepted 27 August 2018; Published 13 September 2018

Academic Editor: Michael M. Khonsari

Copyright © 2018 Alexey Beskopylny et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The article is devoted to the analysis of the state of the contact surfaces of the higher kinematic pair in the general case of relative motion, that is, in the presence of rolling, sliding, and twisting, which is characteristic of Novikov’s circular-screw gears. The purpose of the work is to assess the impact of friction forces, the state of contact surfaces after tool processing, and the localization of the instantaneous contact spot on the level of contact—fatigue durability of gears. Power contact in the presence of geometric slippage of the mating surfaces leads to a significant change in the initial geometry and the mechanical properties of surface layers. In the existing methods of calculations of contact strength, the effect of running-in is investigated insufficiently, which leads to an incorrect result, especially for gear with high hardness of the teeth. In this work, the conditions of contact interaction close to the real requirements are studied on the basis of experimental material, numerical solution of the contact problem, determination of the terms of the contact areas of slip, and adhesion within the instantaneous spot. The shape of the instant contact spot has asymmetry and can be approximated by an ellipse with the introduction of a correction factor. The running-in period is of a plastic nature with cold deformation and reduction of the roughness of surfaces. As a result of the run-in period, the area of actual contact (tooth height) is increased by 2 or more times. It is not desirable to spread the area of contact at the area of adhesion that initiates the formation of pitting. The presence of defective surface area on the level of contact strength does not have significant influence, because of the running-in period, but increases the risk of spalling and brittle fracture.