Influence of Tip Relief Modification on the Wear of Spur Gears with Asymmetric Teeth

Headnote

KEY WORDS

Wear; Spur Gear; Asymmetric Teeth; Tip Relief

ABSTRACT

Recently, spur gears with asymmetric teeth have been considered a way of increasing performance while maintaining the gearbox dimensions. Asymmetric teeth have different pressure angles on drive and coast sides. They provide, among other advantages, a high bending strength and low vibration. In spur gears with asymmetric teeth, wear has been observed to be a major failure mode. In this study, the impact of tip relief modification and pressure angle on the wear of spur gears with asymmetric teeth is numerically investigated. Here, the focus is on sliding wear A wear model based on Archard's equation is employed to predict wear depth. The pressure angle and the tip relief are parameterized. In the analysis, instantaneous contact loads and Hertz pressures are used in wear depth calculations. It is shown that as the amount of the tip relief increases, the wear depth, particularly at the beginning and end of the mesh, decreases. As the number of wear cycles increases, the effect of the tip relief modification on wear depths decreases slightly. It was also shown that with an increase in tip relief, the dynamic load decreases. However, if the amount of tip relief modification increases excessively, the maximum dynamic load also increases. Therefore, an excessive increase in tip relief modification should be avoided, whereby the level of excessive increase depends on the tip relief configuration.

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INTRODUCTION

Wear on Gears

Wear is one of the major failure modes of gears. Although there are different classifications of wear mechanisms, wear on gears can be simply classified as mild wear, pitting, and severe wear (scuffing), depending on the wear rate. These types of wear may lead to power transmission losses, decreased efficiency, increased vibration and noise, and gear tooth failure. Consequently, during the design process, engineers have to design against tooth wear. For example, mild wear, while allowing for smooth contact at the beginning, will change the contact conditions of the tooth surfaces in a critical way as the wear depth increases, if not taken into account.

To completely understand the wear phenomenon in gears, both experimental and theoretical studies have been carried out and documented (Bajpai. et al.1 Brauer and Andersson2;...