Optimization of Gear Tooth Contact by Helix Angle Modification


This paper reports the results of a study of the effects of helix angle modification on the load distribution and stresses within teeth of helical gears, and the calculation of appropriate compensation for torsional effects.
Load distribution and peak stress for helical gears under normal torsional forces inherent in helical gear drives are significantly influenced by the flexibility of the gear body, tooth structure and elastic deformation of the contact surfaces. Uncompensated, these factors reduce the gear face contact area and accordingly increase maximum stress and decrease pitting resistance and bending strength power ratings.
This paper transforms the calculation of the compensation required by translating the underlying analysis into a MATLAB based program that can be run on a modest, standard PC computer. Informed practicing engineers - as opposed to esoteric experts in whose domain these calculations currently reside - now have a tool to do the necessary calculations with ease.
The results from the program are confirmed by FEA analysis of compensated and uncompensated examples, together with a practical example with an operating, 3,000 kW gearbox. The results show that the program produces the appropriate adjustment, such that the contact areas are full width across the gear faces. The authors' recommendation is, now that a user-friendly analysis tool is available, that helix angle compensation should be included in rating standards.
ISBN: 978-1-61481-104-6 Pages: 13
Authors: S. Hipsley, R.J. Davey, R.T. Wheway
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