Diagnosing the change in the internal clearances of rolling element bearings based on vibration signatures

Several mechanisms of wear can occur in rolling element bearings (REBs). As the wear evolves, the vibration level will increase with the growth of internal clearance of bearings due to the variation of contact force and dynamic excitation. Therefore, for accurate fault severity diagnosis, internal clearance increase caused by inevitable wear has to be taken into account. In this paper, clearance variation caused by the wear of tapered rolling bearings (TRBs) is investigated experimentally and clearance estimation is carried out based on analysis of low frequency vibrations and the deviation of the fault features. An experimental study is ingeniously designed to simulate the wear evolutions and evaluate their influence on well-accepted envelope signatures according to vibrations measured from TRBs. The defective bearings were diagnosed in two aspects: the magnitude variation of vibrations in the low frequency band and the peak frequency deviation. The experimental results give out a signature shift with regard to the wear evolution, also vibration magnitude of the low frequency band grew remarkably. Therefore, unavoidable wear can be estimated and consequently the fault severity diagnosis improved.