The four stages of bearing failure, did you get? - bearing knowledge

Bearing in the process of operation, will slowly because of the reason of the fatigue degradation. As shown in figure 1, the deteriorating development of the rolling bearing is not a linear process, but a process index. In different degradation stages, within the scope of fault information in different frequency band, so should use different methods of fault detection. The industry is generally accepted that the degradation course of rolling bearing can be divided into four stages. Figure 1 a typical bearing fault development first stage 1, early bearing failure, as shown in figure 2. Bearing at this stage in the first time the surface microscopic cracks or lattice mismatch, while bearing surface can't see the crack or small spalling, the vibration signal not obvious impact to low frequency signal, using traditional acceleration sensor can't pick up the fault signal, but The Times or micro crack on the surface of the lattice mismatch will produce acoustic emission signals or stress wave signal. Therefore, at this stage of bearing fault characteristic mainly reflects in the ultrasonic frequency, can through the acoustic emission sensor to pick up or acceleration sensor based on resonance, its main performance for the measured signal peak or energy. Figure 2 bearing degradation of the first phase of the vibration signal characteristics of the second phase, 2 bearing failure period, as shown in figure 3. Bearing at this stage of the micro degradation started from surface to surface extension, and the bearing contact surface crack or small spalling damage point. When surface and the damage point contact bearing components, can form a certain frequency of shock pulse, based on Fourier transform, the short-term impact of the signal in frequency domain is a broadband signal, so the impact signal will inevitably provoke bearing parts of high-frequency inherent frequency resonance occurs, so that the vibration strengthening, through the acceleration sensor can pick up to this part of the signal, using envelope demodulation technique can be observed that the bearing fault characteristic frequency, at the end of the second phase can also observe the frequency doubling fault characteristic frequency. At this stage, bearing fault characteristic frequency temporary submerged in high to low frequency noise, so the fault characteristic frequency observation clear fault characteristic frequency. Figure 3 bearing vibration signals of the second stage of the degradation characteristics of three phase three, bearing failure period, as shown in figure 4. At this stage, with the accelerating development of bearing damage, damage to the impact of the bearing contact surface is more and more intense, in the bearing fault characteristic frequency of resonance frequency demodulation frequency doubling of more and more, and the size of cyclical impact energy was enough to directly observed through the power spectrum of vibration signals, this time can be directly in the clear on the power spectrum of bearing vibration signals of the fault characteristic frequency, and the trend of frequency doubling, more and more. Figure 4 bearing degradation is the third phase of the vibration signal characteristics of four stage 4, the end of bearing failure, as shown in figure 5. At this stage, rolling bearing has nearly reached the end of life, injury point can be seen by the naked eye, the noise of the bearing movement become extremely large, rapid temperature increase. At this point directly on the power spectrum can not only clear bearing fault characteristic frequency and the frequency doubling, if damage points alternately into the load zone, also can see obvious beside the fault characteristic frequency modulation frequency. In the fourth stage of the end of the spectrum lines become is not very clear, will form a bulge in the power spectrum 'thatched heap', also the high frequency vibration energy in also may not rise but lower at this moment, if it is found that the high frequency of monitoring quantity began to decline, not on the surface of bearing condition better, but that the end of the bearing is close to the life. Figure 5 bearing degradation in the fourth phase of the vibration signal characteristics to sum up, as can be seen from the bearing degradation of four stages, the frequency and the faults of bearing fault characteristic frequency characteristic frequency whether frequency doubling frequency are to a certain extent, whether any degradation reaction of the bearing information, from the perspective of the relationship of frequency and time of bearing degradation has a tendency to move from high frequency to low frequency, the first change of ultrasonic frequency measured signal, with the development of bearing degradation, the resonance frequency of the signal can be observed by a certain analysis of bearing fault characteristic frequency, finally within 1 KHZ low frequency signal on the power spectrum of fault characteristic frequency was observed. This shows that with the development of bearing fault, the fault characteristics will gradually move from high frequency to low frequency.