| Full ceramic ball bearings are made of ceramic materials as a whole.Because it often works in some harsh environments such as high temperature,high speed and high corrosion,it is more prone to failure than under normal conditions.During the operation of the bearing,the balls continue to move and continuously squeeze the lubricating oil between the raceways.The oil in the contact center between the balls and the raceways is continuously squeezed out.The internal lubrication conditions have also changed from initial full lubrication to starvation lubrication.When the bearing is under starved lubrication conditions,resulting in an increase in contact stress,aggravating bearing vibration,and affecting the dynamic characteristics of the full ceramic ball bearing.Therefore,it is necessary to study the dynamic performance of full ceramic ball bearings under different lubrication conditions.This paper studies this problem and studies several key elements.First of all,according to the bearing dynamics theory,the force situation of the full ceramic ball bearing is analyzed,the contact stress and deformation between the balls and the inner ring are considered,and the working conditions of high speed and load are considered.A dynamic model of full ceramic angular contact ball bearings under sufficient lubrication conditions is established.The force in the contact area between the ball and the inner raceway is calculated as the input parameter for the numerical analysis of elastohydrodynamic lubrication.Based on the elastohydrodynamic lubrication theory and Hertz contact theory,the calculation method of oil film thickness is determined.The calculation method for judging the critical value of starvation lubrication and sufficient lubrication is deduced,and then the dynamic model of full ceramic angular contact ball bearing is established under the premise of starvation lubrication.The lubrication numerical analysis is carried out on different lubrication conditions,and the lubrication conditions are explored the influence of the dynamic characteristics of full ceramic ball bearings.Combining elastohydrodynamic lubrication and dynamics theory,the thickness of the oil film when lubrication is exhausted and the position of the starting point of the lubricating oil film to determine whether it is in starvation lubrication conditions are analyzed.The analysis shows that the film thickness increases rapidly at first and then remains unchanged with the increase of initial oil supply.The analysis results show that the vibration amplitude when the bearing is under starvation lubrication is greater than the vibration amplitude when the bearing is fully lubricated,and the operation of the bearing changes with the improvement of lubrication.The influence of rotational speed and load on radial and axial vibration of bearings is different.The vibration of the bearing increases with the increase of the curvature coefficient of the inner channel.The pitch circle diameter has a small influence on the bearing vibration,and with the bearing pitch circle as the diameter increases,bearing vibration decreases.According to the working principle and key technology of the ceramic electric spindle machine tools,establish a spindle test system,and a vibration detection platform to analyze the influence of speed and applied load on the performance of the bearing,and compare the previous theoretical analysis data with the data measured by the experiment.This paper establishes a model for dynamic analysis of full ceramic ball bearings under different lubrication conditions.The vibration characteristics and influencing factors of full ceramic ball bearings under different lubrication conditions are studied,which lays a theoretical foundation for further improving the structural design parameters of the bearing. |
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