Study On Lubrication Characteristics Of Tripod Universal Coupling Of Cylindrical Roller

The tripod universal coupling of cylindrical roller is a kind of high-performance universal coupling based on elastohydrodynamic lubrication theory.It is helpful to improve the lubrication characteristic and resistance to wear by replacing the plane contacts with line pairs.Based on the kinematic and kinetic characteristics of the coupling what have been studied in detail by the research group previously,the lubrication characteristics of coupling under actual work conditions were analyzed based on the linear contact elastohydrodynamic grease lubrication model in this paper.And then experiments were carried out to verify the theoretical results so as to lie the foundation for further research.The main research contents are as follows:(1)The development of elastohydrodynamic lubrication theory and experiment at home and abroad was introduced and summarized.The purpose,contents and significance of this paper were put forward.(2)Based on the simplified geometric structure of coupling,the numerical model of linear contact elastohydrodynamic grease lubrication was established and solved.The isothermal analysis and thermal analysis under different parameters were carried out respectively.The conclusion shows: the larger loads result in higher pressure and thinner film thickness,the higher velocity increases the second pressure peak and film thickness mainly,and the second pressure peak and minimum film thickness of film under thermal elastohydrodynamic condition are lower slightly.(3)Because the temperature has a great influence on friction pairs and grease,the lubrication characteristics of film under different geometric parameters,grease characteristics and solid particle factors were solved and compared under the steady-state work conditions in this paper.The conclusion shows: reducing the anglebetween the input shaft and the output shaft,reducing the gyration radius of the input axis and increasing the radius of cylindrical roller all reduce the film pressure and temperature rise,however,the former two slightly reduce the film thickness,while the latter increases it.Increasing the initial viscosity and rheological index of grease increase the pressure,thickness and temperature rise of film at the same time.Solid particles in grease are liable to cause sudden changes in film pressure and temperature rise.The larger the particle radius is,the more obvious the film instability is.(4)Because of the strong time-varying property of grease,the state of film changes over time.In this paper,on the premise that the cylindrical roller was subjected to periodic impact load,transient squeeze analysis at different frequencies and cavitation analysis of film were carried out.The conclusion shows: the higher the time-varying frequency is,the greater the gap between the transient and the steady-state solution is;when the negative pressure of film is considered,increasing the inlet pressure properly can effectively suppress the formation of cavitation area.(5)For isothermal numerical calculation model established for Chapter 2,two groups of experiments of variable load and variable speed were carried out on a multi-functional two-color photoelastohydrodynamic lubrication film measurement tese rig under pure roll condition.The experimental and theoretical results were compared and the reasons for the errors were analyzed.The validity of the model was verified and the basis for deeper elastohydrodynamic lubrication analysis of the tripod universal coupling of cylindrical roller was provided.