Investigation Of Nano-grease And Functional Surface On The Performance Of Grease Lubricated Rolling Bearing

Rolling bearings are the core support parts of rotating machinery,with the development of China’s advanced equipment manufacturing industry,the stable operation of bearings in various types of extreme working conditions has put forward higher requirements.Although the quality of domestic bearings is gradually improving,there is still much room for progress in terms of high precision,long life,low vibration and high reliability of bearings.With the popularization of precision grinding and ultra-precision grinding technology in the field of bearing processing,surface roughness and machining accuracy are no longer the main factors limiting the quality of bearings.Since most of the bearing failures are caused by lubrication failures,it is of great theoretical significance and engineering application value to improve the bearing lubrication condition to reduce bearing vibration and friction and meet the demand of various extreme working conditions.This paper intends to carry out research on the effect of nano-added grease and functional surface on the performance of grease lubricated rolling bearings.The main research contents of this paper are:（1）Study the effect of nano-additive on the tribological and vibration suppression performance of grease.In this study,a lithium complex grease was prepared as the base grease,and three kinds of nanoparticle（Al₂O₃,Fe₃O₄,C）with different hardness and morphology were used as additives.The thickener structure and nanoparticle morphology were observed by scanning electron microscopy.The tribological properties of the nano-additive grease were analyzed.The friction coefficient and wear spot morphology of each grease were analyzed based on four-ball friction and wear experiments,and the elemental distribution of wear surfaces were analyzed by EDS to explain the mechanism of different hardness nanoparticles in boundary lubrication.The vibration suppression performance of the four prepared greases was evaluated by using BVT-1A bearing vibrometer.The vibration signals of 6204 deep groove ball bearings were collected,the vibration damping performance of each grease was analyzed and evaluated in three frequency bands:low,medium and high,and the mechanism of the action of nanoparticles in the oil film was established.The base oil contact angle experiment was conducted,and the results showed that the nanoparticles would enhance the wettability of the base oil on the thickener surface and could promote the reflow of base oil in the bearing raceway to relieve vibration.（2）In order to solve the starve condition of grease lubricated bearing,this paper applies the density gradient grooved microstructure on the guiding surface of thrust ball bearing,expecting to improve the bearing lubrication by promoting the reflow of base oil to the raceway through its oil self-driving function.In this paper,firstly,evaluated the spreading performance of PAO40 base oil on non-textured and three types（gradient groove,uniform groove,dimple）of textured steel plates respectively.Then,the vibration test of the bearing with textured guiding surface was carried out by using BVT-7A bearing vibrometer and analyze the vibration signals in time domain and frequency domain to carry out the mechanism of the textured guiding surface on the improvement of bearing lubrication.Finally,the bearing friction torque test was conducted and SEM images of the raceway surface were taken after the experiment.The experimental results show that the gradient grooved guiding surface can effectively promote the supply of bleed oil to the raceway,which can effectively reduce the vibration in the bearing and reduce the wear.