Tribological Analysis Of Needle Roller Bearings In RV Reducer

Industrial robots are widely used to replace people to complete a variety of repetitive workand labor in special environment.They are gradually changing our human society.China has ahuge market for robots,but the market has been monopolized by foreign companies for manyyears.Thus it is a significant national strategic target to realize the localization of industrial robotsand the most important and hardest part is the research and development of RV reducer.And,theworking performance and service life of the swivel needle roller bearings in the RV reducerseriously restricts the reliability of the whole reducer.Based upon the research of rolling bearings lubrication theory,this thesis studied thelubrication characteristics of the needle bearings in RV reducers.The film pressure and itsthickness and the Mises stress filed of the subsurface of the bearings were analyzed with thelubrication model and MATLAB program,and the performance of the bearings were qualitativelyand quantitatively examined.The first part of this thesis described the engineering significance of the tribological analysisof needle roller bearings in RV Reducer,and summarized the research progress of the theoreticaland experimental study of elastohydrodynamic lubrication(EHL)in line contact friction pair athome and abroad.And the common film thickness formulas and the solving methods for EHLmodel are reviewed.The second part modeled the elastic deformation of the surface in line contact,and then thedeformations under Hertz pressure distribution,triangular pressure distribution and uniformpressure distribution were computed with five methods and the five methods were comparativelyassessed.The third part established the model of EHL with considerations of surface waviness anddimples,and solved the lubricating film pressure and film thickness as well as sub-surface Misesstress of bearings with through the system method and MATLAB.The effects of different wavelengths and amplitudes,diffferent dimples locations and depths in the inlet,central and exit zoneon the film pressure and thickness,subsurface Mises stress field under both light and heavy loadwere computed,and the amplitude and location of maximum stress were comparatively analyzed.The effects of surface waviness and dimple on lubrication of needle roller bearings were obtained.The fourth part modeled the grease EHL lubrication based on the Ostwald constitutiveequation,the pressure distribution,film thickness distribution and subsurface Mises stress field of EHL lubricated with grease were analyzed.The effects of rheological index,load and entrainment velocity on the properties of grease lubrication were examined.The fifth part summarized the major work in this thesis,and presented some inadequacies of this approach and proposed the topics that require future research.