Research On The Application Of The VI Technology In Fault Diagnosis Of Bearing

Vibration analysis is widely used in the fault detection of the rolling bearings. Many researches have been made in this paper, In order to build a construction of the fault diagnosis system and seek a right signal processing method in the condition of Virtual instrument.In this paper, the vibration principle of the rolling bearing, the digital signal processing principle, the frequency analysis and wavelet analysis method have been thoroughly studied. A total design project has been put forward, this project adopt PCI (Peripheral Component Interconnect) Bus Instrument to build a rolling bearing fault diagnosis system, many key parts of this system are discoursed in detail. A rolling bearing test rig has been designed and built, and some types of the fault are simulated to verify the method of the fault analysis that has been built in this paper.There is noise in the vibration signals. The frequency of the noise is much close to the defect signature frequency of the bearing. So it is difficult to distinguish the normal and abnormal conditions of the bearing. It is well known that the modulation of vibration signals is decisive signature of the present of a local fault in bearings, the demodulation of these signals will more clearly reveal the signatures. The Demodulated Resonance Technique is used in analyzing the vibration signal of the bearing, a frequency band should be selected, the signal in this band was demodulated by Hilbert transform, then the Zero-Padding-FFT method is used to make the defect signature in the envelop spectrum more easy to be recognized.Wavelet transform is a time-frequency method, wavelet transform has been studied in this paper. Some faults in the bearing can be detected by this method.The experimental factors, such as the characteristic of the sensor, measured position and signal condition are considered in this paper. Many experiments have been done in different sample rate and sample number in order to find out the best factor of the fault diagnosis system.The experiment verified, the Demodulated Resonance Technique is a right method in vibration signal processing in the rolling bearing fault diagnosis.