The four stages of rolling bearing failure development

Update:19-11-2021
Summary:

Corresponding to the structural composition of rolling […]

Corresponding to the structural composition of rolling bearings, rolling bearings have 4 types of failure frequencies: rolling bearing cage failure frequency, rolling bearing rolling element failure frequency, rolling bearing outer ring failure frequency, rolling bearing inner ring failure frequency. For these bearing failure frequencies, there are special mathematical calculation formulas, but calculations are more troublesome in actual work. The more convenient method is to use special software to obtain, such as the Rockwell Automation software in the United States. With this function plug-in, as long as you enter the bearing model and manufacturer and other information, you can get the corresponding frequency of various bearing failures.

The first stage is the embryonic stage of bearing failure. At this time, the temperature is normal, the noise is normal, the total vibration speed and frequency spectrum are normal, but the total peak energy and frequency spectrum have signs, reflecting the initial stage of bearing failure. At this time, the real bearing failure frequency appears in the range of about 20-60khz in the ultrasonic section.

In the second stage, the temperature is normal, the noise increases slightly, the total vibration speed increases slightly, and the vibration frequency spectrum does not change significantly, but the peak energy increases greatly and the frequency spectrum becomes more prominent. The bearing failure frequency at this time appears in the range of about 500hz-2khz.

In the third stage, the temperature rises slightly, noise can be heard, the total amount of vibration speed increases greatly, and the bearing fault frequency and its harmonics and sidebands are clearly visible on the vibration speed spectrum. In addition, the noise level on the vibration speed spectrum is obvious. Increase, the total amount of peak energy becomes larger than the second stage, and the frequency spectrum is more prominent. The bearing failure frequency at this time appears in the range of approximately 0-1khz. It is recommended to replace the bearing in the later stage of the third stage, then the rolling bearing failure characteristics such as wear and tear that can be seen by the naked eye should have appeared at this time.

In the fourth stage, the temperature rises significantly, the noise intensity changes significantly, the total vibration velocity and the total vibration displacement increase significantly, and the bearing failure frequency on the vibration velocity spectrum begins to disappear and is replaced by a larger random broadband high-frequency noise level; The total amount of peak energy increases rapidly, and some unstable changes may occur. The bearing must not be allowed to operate in the fourth stage of failure development, otherwise catastrophic damage may occur.
According to the research results, in general, if the entire service life of a rolling bearing is counted from the time the bearing is installed and put into use, the bearing is normal in its first >80% service life. And then corresponding to the development of rolling bearing failure, the remaining life in the first stage is 10% to >20%L10, the second stage is 5%-10%L10, the third stage is 1%~5%L10, and the fourth stage is about It is 1h or 1%L10.

Therefore, when facing bearing problems in actual work, considering that the fourth stage of bearing failure development has unforeseen sudden hazards, it is recommended to replace the bearings in the later stage of the third stage, so as to avoid the expansion of failures and more serious accidents. It can ensure the service life of the rolling bearing as much as possible, and it is more convincing based on the fact that there are already visible wear and component damage on the bearing at this time. As for the identification of the later stage of the third stage of bearing fault development, it needs to be comprehensively considered based on the above theoretical characteristics and combined with the actual temperature, noise, speed spectrum, peak energy spectrum, the total trend of speed and peak energy, and actual experience.

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