Effects Of Axial Preload On The Vibration Properties Of Angular Ball Bearing Rotor System

It is well known that rolling bearings, especially angular contact ball bearings, must be preloaded when installing in order to improve the positioning precision, rotational accuracy and stiffness, decrease vibration and noise, extend the working life. Axial preload will affect the vibration properties of angular ball bearing rotor system. Therefore, it is important to study the effects of axial preload on the vibration properties of angular ball bearing rotor system.Through geometric analysis of the angular contact ball bearing and the force balance, the contact load-deformation expressions of ball-to-raceway, the expression of load zone and their relation to axial preloading displacement are developed with taking the off-sized balls and raceway error into account. Load distribution and FFT spectral analysis of inner ring center displacement are numerically studied with and without considering the off-sized balls and raceway error. According to the stiff definition and mechanical analysis, a model for calculating the bearing radical stiffness and axial stiffness are established, which can investigate the effects of axial preload on bearing stiffness with consideroffing the balls’ and raceways’errors. By using empirical formula of damping from M Sarangi, taking the Jeffcott rotor supported by angular ball bearing as a research example, a set of curves about the maximum amplitude and critical speed related to the axial preload displacement are obtained and analyzed. By using transfer matrix method and taking Jeffcott rotor and a complicated rotor model as research examples, this thesis investigated the effects of Axial Preload on the vibration properties of rotor system furtherly such as critical speed and unbalanced respond amplitude with considering the errors of ball and raceway.Through investigation, it is reveals that the effects of axial preload on the vibration properties of angular ball bearing rotor system, and a set of curves and conclusions are obtained. The results of this thesis will be helpful in application and research of angular ball bearing, as a reference.