بررسي تاثير اصلاح پروفيل دندانه بر عملكرد ترابيولوژيكي چرخ دنده ي ساده تحت رژيم روان كاري الاستوهيدروديناميك مخلوط

چكيده انگليسي :

89 On the Effect of Profile Modification on the Performance of Spur Gears in Mixed EHL Regime Masoud Kimiaei M Kimiai@me iut ac ir Date of Submission 2015 08 14 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Saleh Akbarzadeh s akbarzadeh@cc iut ac irAbstract Gears are used for power transmission between two axes that they have often mechanical advantageslike increasing or decreasing the torque from one shaft to another or the rotational speed Spur gears are themost important tools for power transmission in the industry that can be considered the most commoncomponents of the transmitter force among the mechanical systems Like other parts of a system Gearsconsume a large amount of power and they may damage seriously such as wear fatigue failure So theimprovement in the design and modification of tooth profile of gears can significantly reduce friction lossand wear the gear teeth and therefore it effect on increasing life maintaining the quality of performance andCost reduction As is commonly the case in the analysis of most tribological components the keyparameters of interest in gears are the lubricant film thickness the dimensionless film parameter and thecoefficient of friction The first two parameters are important in terms of reliability and damage while thethird parameter is a measure of the efficiency of the gear set in terms of the required power In indusrialapplications the friction coefficient between the moving contacting surfaces is of vital importance in termsof power loss Another influential parameter in lubricanted tribosystems is the roughness of the surfaces i e the micro geometrical irregularities of the surfaces Gears usually operate under the mixed lubricationregime Hence it is always of interest to predict the portion of load carried by asperities as well as frictioncoefficient The aim of this research is to present a model that takes into consideration the addendummodification surface properties gear geometry loading conditionand velocity condition as the input andpredicts the film thickness friction coefficient along the line of action LOA In this model the contact ofgear teeth at each point along the line of action is represented by the contact of two cylinders where theradii of these cylinders vary along the line of action The contact model for rough surfaces introduced byGreenwood and Williamson 1996 assumes that the asperities deform elastically however in reality whenthe contact pressure exceeds the yield strength of the material elastic pelasticdeformation occurs Theseparation between two rough surfaces is given by the film thichness which would exists between twosurfaces under the same conditions of load speed and lubricant in this research the model of Zhao et al ofrough surfaces in contact has been combined with Moes central film thickness equation and load sharingconcept of Johnson et al use to predicting the film thickness friction coefficient load carried by film andload carried by asperity a long line of action Finally subsurface stresses are obtained using the coefficientof friction and hertzian contact model The purpose of this study is showing the influence of addendummodification on performance of spur gears and the effect of that on Power distribution friction coefficientand Load tolerated by the lubricant film and roughness This model can be used as a rapid prediction for themodified gear performance Keywords Spur gear addendum modification Elastohydrodynamic mixed lubrication frictioncoefficient wear rate

كيميايي، مسعود

بررسي تاثير اصلاح پروفيل دندانه بر عملكرد ترابيولوژيكي چرخ دنده ي ساده تحت رژيم روان كاري الاستوهيدروديناميك مخلوط

ضريب اصطكاك , سايش