Real contact ratio and tooth bending stress calculation for plastic/plastic and plastic/steel spur gears

Toni Jabbour,Mohamad Abdulwahab,Ghazi Asmar,Jose Nasr

doi:10.1051/meca/2021029

Toni Jabbour, Mohamad Abdulwahab + Show 2 more

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https://doi.org/10.1051/meca/2021029

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Abstract

This paper presents an iterative method for calculating the effective contact ratio and the bending tooth stress for a pair of plastic/plastic and plastic/steel spur gears with an involute profile. In this method, the pinion and the gear are modeled, at each moment of the mesh cycle, as equivalent springs in parallel undergoing the same displacement along the line of action. This leads to the calculation of the bending stress by taking into account the number of teeth initially in contact and those which enter in contact prematurely. We also investigate the influence of certain gear parameters, such as, the number of teeth, the pressure angle, and the module on the behavior of a pair of meshed gears. In addition, the variation of the bending stress at the tooth fillet is investigated for a pair of plastic/plastic and a pair of plastic/steel spur gears, in order to determine the critical configurations for which the bending stress is maximum. In general, the results obtained from the present method also show that the stress variation in plastic/plastic gears differs markedly from that in plastic/steel gears.

Highlights

Plastic gears are commonly used in many applications, such as, in motor vehicles, office machines, home appliances, and other pertinent systems and devices
We propose a method to calculate the real contact ratio and tooth bending stress of a pair of plastic/plastic and plastic/steel gears subjected to an applied torque T
A parametric investigation is carried out to study the effect of increasing the number of teeth of both the pinion and the gear, of the module and of the pressure angle on the variation of the real contact ratio and on the variation of the bending stress

Summary

Introduction

Plastic gears are commonly used in many applications, such as, in motor vehicles, office machines, home appliances, and other pertinent systems and devices. Among the earlier research undertaken on the behavior of plastic gears, one finds the works by Hall et al [2] and Cornelius et al [3] In these works, high speed photography of an acetal/acetal gear pair transmitting load, and measurements of contact ratios show that several teeth carry the load at all times. A recent literature review shows a keen interest in the study of the structural analysis of plastic/plastic spur gears [5,6,7,8,9,10,11,12]. This is an addition to the development of analytical-

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