Double Impulses Extraction And Analysis Of Faulty Hybrid Ceramic Ball Bearing Based On EEMD

Hybrid ceramic ball bearing is one of the most key parts of high speed motorized spindle, which is widely used in high-end machine tools and other high-speed equipment. However, researches on the methods of fault detection and damage degree evaluation of the hybrid ceramic ball bearing are extremely limited at present. Then, it has an important practical significance for the related research. By extracting the double impulses from the corresponding vibration is a novel way for measuring the size of the spalls in the bearing under the operating condition. It plays an important role in solving the reliability, security operation problem of the high speed machine tools and other high-end equipment using the hybrid ceramic ball bearing as its key part. Then, the related study is important for potential applications. In this thesis, the double impulses extraction and analysis methods of faulty hybrid ceramic ball bearing is well studied. The reasons of the double impulse phenomenon are investigated and the corresponding vibration and the characteristics generated by the faulty bearings are analyzed. The noise reduction methods and the weak signal feature enhancement techniques are also presented and employed during the research work.Based on the analysis of rolling element bearing vibration mechanism, the typical failure forms and the vibration signal characteristics of the bearing with spalls are summarized in this thesis. Then, experiments on the hybrid ceramic ball bearings are carried out for investigating the cause of the double impulses, the time interval of the double impulses, the spectrum distribution of vibration signal and the relationships of the double impulses with the bearing speed, faulty sizes and the relative position between sensors and fault location, and detailed the findings in this thesis. The AR filtering pre-whiten algorithm based on the maximum kurtosis and the envelope extraction based on Hilbert are also introduced in detail. In addition, a series of the non-stationary signal processing methods are discussed. The principles of the empirical mode decomposition (EMD) and the ensemble empirical mode decomposition (EEMD) are discussed. An adaptive noise reduction method based on the EEMD is proposed after a comparatively analysis the performance between the EMD and the EEMD. Consequently, an envelope extraction scheme based on the EEMD is proposed in the thesis for the double impulses extraction of faulty hybrid ceramic ball bearing. The detailed steps of the proposed approach have been presented in this thesis. Finally, simulations and test experiments are introduced respectively to verify the validity of the proposed method.