Rolling bearing operating status identification:
As a measurement parameter that indicates early faults, the demodulation spectrum, combined with the velocity spectrum, is the key to determining bearing faults. The development process of rolling bearing failure is divided into 4 stages.
(1) There is no bearing failure frequency, the condition is good, and it will continue to be monitored as a baseline;
(2) There is a fault frequency only in the demodulation spectrum, early fault indication, or lubrication is required;
(3) There are spectral peaks in both spectrums, and the next maintenance is planned to replace the bearings;
(4) There are peaks only in the normal spectrum, while the noise level increases in the demodulated spectrum, replace immediately.
The characteristics of bearings at each stage are as follows:
The first stage: (1) Noise is normal; (2) Temperature is normal; (3) Ultrasonic, vibration demodulation spectrum and acoustic emission measurement values exceed the standard, and the bearing outer ring is defective; (4) The total vibration is small, and there are no discrete bearing failure frequency spikes; (5) The remaining life of the bearing is greater than 10% specified in B-10.
The second stage: (1) The noise increases slightly; (2) The temperature is normal; (3) Ultrasound, vibration demodulation spectrum, and acoustic emission measurement values increase significantly, and the bearing outer ring is defective; (4) The vibration increment increases slightly (the total vibration acceleration and vibration Speed total); (5) The bearing failure frequency can be clearly seen on the spectrum on the logarithmic scale, but it is difficult to see on the spectrum on the linear scale, and the noise is significantly increased; (6) The remaining life of the bearing is greater than 5% specified in B-10.
The third stage: (1) Noise can be heard; (2) The temperature rises slightly; (3) Very high ultrasonic, acoustic emission, demodulation spectrum pass-frequency values; (4) The total amount of vibration acceleration and vibration speed increases greatly; (5) The bearing failure frequency and its harmonic frequencies and sideband frequencies are clearly seen on the linear scale spectrum; (6) The noise level of the vibration spectrum increases significantly; (7) The remaining life of the bearing is greater than 1% specified in B-10.
Four stages: (1) The intensity of the noise changes; (2) The temperature rises significantly; (3) The pass frequency value of ultrasonic, acoustic emission, and vibration demodulation spectrum increases rapidly, and then gradually decreases, and the bearing outer ring is in the fault state before damage; (4) The total vibration speed and total vibration displacement increase significantly, and the total vibration acceleration decreases; (5) The bearing failure frequency with lower frequency is dominant, and the non-remaining life of the noise level in the vibration spectrum is greater than 0.2% specified in B-10.
The article is excerpted from "Rolling Bearing Fault Judgment and Analysis" by Wang Zhitang, Cao Zhibao and Hou Jinpeng. It is for your reference only.