Volume 2, Issue 1, 2011

Compact Design for Non-Standard Spur Gears

Tuan Nguyen and Hsiang H. Lin

Abstract

This paper presents procedures for compact design of non-standard spur gear sets with the objective of minimizing the gear size. The procedures are for long and short addendum system gear pairs that have an equal but opposite amount of hob cutter offset applied to the pinion and gear in order to maintain the standard center distance. Hob offset has shown to be an effective way to balance the dynamic tooth stress of the pinion and the gear to increase load capacity. The allowable tooth stress and dynamic response are incorporated in the process to obtain a feasible design region. Various dynamic rating factors were investigated and evaluated. The constraints of contact stress limits and involute interference combined with the tooth bending strength provide the main criteria for this investigation. A three-dimensional design space involving the gear size, diametral pitch, and operating speed was developed to illustrate the optimal design of the non-standard spur gear pairs.  Operating gears over a range of speeds creates variations in the dynamic response and changes the required gear size in a trend that parallels the dynamic factor. The dynamic factors are strongly affected by the system natural frequencies. The peak values of the dynamic factor within the operating speed range significantly influence the optimal gear designs. The refined dynamic factor introduced in this study yields more compact designs than those produced by AGMA dynamic factors.  Full Article