Bearing fault diagnosis

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1. The rolling bearing fault simulation experiment and data collectionBearing fault diagnosis Experiment to choose the type 6208 rolling bearing as monitoring objects, collected vibration signals of rolling bearings. In the process of experiment, install the rolling bearing in rolling bearing test bench SKF 6204 Bearing Parameter frame, driven by a motor bearing rotation, the stage is equipped with frequency converter, easy to adjust motor speed, as well as the positive and reverse direction. Piezoelectric accelerometer for ED - type 3 for acquisition of rolling bearing vibration signal, charge amplifier with DHF - 6 a, PCI data acquisition card used research China - 1711 - a/D card. Installation using magnetic adsorption manner, 23 hz frequency of the inverter control, motor speed n = 1380 r/min, is set to 40 times the charge amplifier, acquisition frequency 10 k. According to different types of bearing fault, the bearing can be divided into normal bearing, fault bearing outer ring and inner ring fault bearing three state. Collect data at the state of three kinds of rolling bearings, 10 sets of data, each state in each group data of 10 samples, each sample 10000 points.Bearing fault diagnosis 2. Rolling bearing fault diagnosis system design Rolling bearing fault diagnosis system block diagram as shown in figure 2. Piezoelectric accelerometer in the bearing vibration signals were collected after work into the A/D conversion card after charge amplifier is converted into digital signal, the time delay correlation demodulation analysis by computer and extract the feature, by the characteristics of fault diagnosis of rolling bearing type, the staff can be based on the results of rolling bearings for maintenance, repair, change, and so on. 3. The time delay correlation demodulation diagnosis Test, the motor speed of 1380 r/min, fault bearing fault characteristic frequency is as follows:Bearing fault diagnosis Outer ring fault characteristic frequency fo = 90.7 Hz, the inner ring fault characteristic frequency fi = 139.3 Hz, ball bearing fault characteristic frequency f r = 51.9 Hz, maintains the fault characteristic frequency fb = 9.07 Hz. Malfunctioning of the roller bearing inner and outer ring, usually in the vibration signal can appear some periodic pulse. But these cycles pulse in the time domain waveform figure it is hard to determine whether the bearing inner ring and outer ring failed. Figure 3, figure 4 and 5, respectively, for the rolling bearing outer ring fault vibration signal of time domain waveform figure, spectral envelope diagram and delay related demodulation spectrum. In the envelope spectrum can be seen in the outer ring fault characteristic frequency (90.7 Hz) near a convex peak, two, three times and the frequency composition is also prominent, show that the bearing outer ring fault occurs. But relative to the figure 5 the delay of related demodulation spectrum, spectral envelope of the fault characteristic frequency without delay correlation demodulation spectrum, the good, and the noise is big, complex spectrum components. Another frequency components in figure 4 (140.8 Hz) of the existence of the rolling bearing fault frequency corresponding to the inner ring, do not tally with the actual situation, if directly according to the spectral diagnosis easily misdiagnosed. And figure 5 delay correlation demodulation spectrum characteristic frequency and multiple frequency components are outstanding, and the noise influence is small, can accurately diagnose the fault bearing outer ring.Bearing fault diagnosis