Enhancement of Bending Strength of Helical Gears by Using Asymmetric Involute Teeth Profiles

Abstract

This paper presents an alternative method to enhance the bending stress for helical gears achieved that by using Asymmetric Involute Teeth Profiles. Theoretically, ??the bending stress of a symmetric gear tooth is calculated by classical Lewis equation (1892), then this equation is developed by M.Q. Abdullah (2012) to take into account the effect of asymmetry of tooth profiles. In this paper, the bending stress for helical gear teeth with asymmetric profile has been calculated analytically by modifying the M.Q. Abdullah equation. In this paper, analytically this equation has been modified to find the bending stress for helical gear with asymmetric teeth at a specified number of teeth (14 teeth) at any helix angle. Also this value has been verified by using numerical solution based on the finite element method technique that done by the software Autodesk simulation mechanical is package v2014. Where the generation process of helical gear have been modelled by using 3D CAD Graphics Software Autodesk inventor professional 2014. The results of this work indicate to the most important conclusion of a helical gear drive with asymmetric teeth profiles having loaded side pressure angle of ( ) and unloaded side pressure angle of ( ) is better than a helical gear drive with symmetric teeth profiles having standard pressure angles of ( ) from the point of view of tooth bending strength. There are significant enhancement in the results of maximum tooth bending stress for asymmetric involute of tooth gear compared with the standard gear. In addition, the results demonstrate optimum helix angle is ( ) which has the highest enhancement percentage.

Keywords: Gear, Helical, Involute profile, Asymmetric, Bending Stress, Autodesk inventor, Simulation.