Under EHL Worm Drive Friction Characteristics Analysis And Friction Design

In this paper,under EHL the friction characteristics and friction design of worm drive are studied.By combining the Hertz contact theory and the Reynolds lubrication theory,solving Method of line contact EHL problem is explored in order to solve the calculation of the minimum oil film thickness.In this paper,the influence of specific parameters on the lubrication characteristics of worm drive is studied.Exploring the influence factors of the minimum oil film thickness so as to provide a way to reduce friction and wear,and get friction design.Then CATIA software is used to build the worm drive model,and worm gear’s three meshing points’ experimental data are calculated,such as the minimum oil film thickness,the film thickness ratio,friction coefficient and friction.In this paper,four sets of experimental data are designed.The independent variables are the oil viscosity,the worm speed and the surface roughness in order to explore the independent variables on the worm drive’s minimum oil film thickness,film thickness ratio,friction coefficient and friction force.The friction characteristics of worm drive under EHL are full of analysis.Finally,the strength design of worm drive and the lubrication design with the minimum oil film thickness are combined tightly in order to build the friction design formula of worm drive.The friction design not only meets the requirement of the tooth surface contact fatigue strength,but also reduces the unnecessary friction and wear in the worm drive,thus meeting the lubrication requirements of the contact surface.Research and data of worm drive obviously have less related to EHL problems of the gear and rolling bearing,so the study of worm drive under EHL has more practical significance and necessity.Only by understanding the friction and lubrication problems of worm drive,the friction characteristics of worm drive can be grasped as a whole,in order to have better design methods and guidelines,and improve the service life and transmission efficiency of worm drive.The EHL theory is a branch of mechanical tribology.The research content of this paper also provides the basis and reference for other parts on friction characteristics and friction design.On the other hand,the main friction of worm drive is the sliding friction which is different from rolling friction of gear and other parts,so the contact surface of worm drive is more to have friction and wear so that the requirments of lubricating oil,lubricating method and device will be greater.The friction heat can bring much problem to worm drive.When the temperature increases,the viscosity of lubricating oil will be reduced and it will produce much effect on the friction characteristics of worm drive under EHL.So the physical property of lubricating oil is also the problem that should be paid attention.Through the above discussion,this paper expounds the content and significance of this study.T his article through each chapter respectively describes the different friction characteristics of worm drive under EHL.The relationship between friction characteristics is clearly explained by experimental data.