Refinement Envelope Analysis For Small Failures Of Rolling Bearing

In the recent years, the technology of fault diagnosis in the machine has a great development both at home and abroad, and it plays a more and more decisive role in the national production. Rolling bearing is one of the important parts in the rotating machinery. Its operating state directly affects the shaft, the gear installed in the shaft and even the performance of the whole equipment. The defects often generate abnormal vibration and noise in the equipment, serious fault would cause the equipment damage, discontinued and big accidents of equipments. Therefore, it is very important to detect state and do fault diagnosis of rolling bearing. Especially it is necessary to diagnosis early small fault diagnosis of rolling bearing.This paper describes fundamental conditions of current fault diagnosis and conditions in bearing. Then it summarizes the mechanism, major failure modes and the methods of monitoring and diagnosis of rolling bearing typical faults. Then the general method is discussed including the basic principles of power spectrum, envelope demodulation and Hilbert transform. Rolling bearing 6202 is taken as an example. Vibration signals are got by the bearing vibration measuring instrument DBV I. According to the characteristics of rolling bearing defect signals and the feature which integrate of wavelet transform, Hilbert transform and envelope spectrum detailed analysis, this text proposed a method, the first step of the method is to reconstruct bearing vibration signal from wavelet filter, second obtain envelope signal by Hilbert transform, and third obtain vibration spectrum from refining the envelope spectrum, finally judging bearing failure from refining the frequency spectrum. This method has completed the diagnosis process, effectively realized fault diagnosis of the rolling bearing, the effectiveness of the proposed method can be verified by the experiment.The typical fault diagnosis of the rolling bearing is successfully achieved, which provides powerful evidences for use of rolling bearings in rotating machines and offers a new idea of judgment, diagnosis in the mechanical fault.