Study On Vibration Characteristics And Mechanism Of Cage Of Cylindrical Rolling Bearing Under Internal And External Excitation

Rolling bearing is the core basic component of industry and has been widely used in aerospace,machine tools,construction machinery and other important fields.As bearings move towards high-speed and high-precision requirements the premature failure of bearings caused by cage’s abnormal vibration is becoming more and more serious.Therefore,the research on cage vibration instability and failure mechanism and cage dynamic characteristics will be conducive to understand the cage transient dynamic behavior clearly,and has great significance to reduce cage failure and improve bearing life and accuracy.Aiming at the failure of rolling bearing caused by cage’s abnormal vibration,in this paper,taking the cage of cylindrical roller bearing as the research object,the interaction relationship between the cage and the roller and the guide ring is further considered,and a more systematic and perfect bearing dynamics model is established.Simultaneously,the simulation results combined with the experimental,theoretical and literature results comprehensively verify the validation of the model built in this paper.The cage’s vibration characteristics and mechanism are compared and studied under internal and external excitation,the corresponding relationship between cage vibration failure and bearing operating conditions and bearing structural parameters is revealed.The external excitation is load fluctuation and oscillation,and the internal excitation is considered as fault and it’s evolution.The main contents are as follows:(1)According to the structural characteristics of cylindrical roller bearings and combined with the kinematics and dynamic principles of rolling bearing,a three-degree-of-freedom dynamic model considering the cage is established and verified.For the cage vibration mechanism in the process of variable load,the cage vibration index in the stable stage of rotating speed is selected as the evaluation data,and the cage vibration and motion stability under the load fluctuation frequency,fluctuation amplitude,average load and different forms of periodic load fluctuation conditions are respectively compared with the stable load conditions.The results show that compared with the stable condition,the number of collisions between the roller and cage increases significantly when the load fluctuates.With the increase of load fluctuation frequency under low frequency load,the vibration degree of cage decreases gradually.At high frequency load stage,the cage’s movement and collision is unstable,and the vibration degree of cage increases with the increase of fluctuation frequency.The greater the average load,the greater the degree of restraint of cage’s vibration.From the impact frequency and impact amplitude,the collision degree and impact sharpness of the cage are the largest under the periodic rectangular wave load and the cage’s wear is the most serious,the harmonic wave load takes the second place,and the triangular wave load has the smallest impact.(2)In order to study the cage’s vibration mechanism during the oscillating,the inner ring oscillating excitation is introduced on this basis,and the transient vibration dynamic behavior of the cage under different oscillating working conditions and bearing structure parameters is studied.The results show that during the oscillation,the vibration of cage presents periodicity,and the vibration mainly occurs in the lift stage reversely,the cage has lower vibration degree in the return stage.When the swing angle is given,the higher the swing frequency,the larger the cage’s impact amplitude,the characteristic frequency and the amplitude corresponding to the characteristic frequency,the more severe the vibration,the sharper the impact response and the more impact components.The greater the vibration degree of cage caused by the increase of swing angle and pocket clearance,the sharper the impact,and the worse it is for the stability and service life of cage.The mass of the roller has significant influence on cage’s vibration,the cage’s vibration amplitude and frequency are significantly increased with the increase of the mass of the roller,and the collision frequency between roller and cage is accelerated,and the collision degree is intensified.Within a certain range,the cage’s vibration degree increases with the increase of the number of pockets.(3)To study the vibration characteristics and mechanism of the cage under the excitation of outer ring peeling fault.Based on the above verified model,the time-varying displacement,time-varying stiffness and viscous damping effect of the roller when roller pass fault are considered.Two typical dynamic models of fault bearing considering cage are established,and the model is verified by combining theoretical analytical solution and finite element results in literature.The results show that the cage’s centroid track of the normal bearing is relatively concentrated,and the cage’s vibration is relatively stable.The cage’s trajectories centroid of fault bearing is more dispersed and disordered,showing vibration instability.Simultaneously,the vibration degree and impact sharpness of the cage increase and gradually increase with the deterioration of the fault.The increase of fault width during early fault has a greater impact on the cage’s impact response and a smaller impact on the vibration degree.When the fault evolves into late fault,the peak value and kurtosis of cage’s vibration shows a trend of increasing first and then decreasing with the increase of fault width,while the RMS shows random oscillation characteristics.For late fault,the force of the rear end of the cage to push the roller increases with the increase of the fault depth,the vibration degree and impact sharpness of the cage are aggravated.