Four stages of the development of rolling bearing failures
Source:未知Author:hyzc Addtime:2022-09-21 Click:
Corresponding to the structural composition of rolling bearings, rolling bearings have 4 kinds of failure frequencies: the failure frequency of the rolling bearing cage, the failure frequency of the rolling element of the rolling bearing, the failure frequency of the outer ring of the rolling bearing, and the failure frequency of the inner ring of the rolling bearing. There are special mathematical formulas for the calculation of the fault frequencies of these bearings, but it is more troublesome to calculate in actual work. The more convenient method is to use special software to obtain them. With this function plug-in, as long as the bearing model and manufacturer are entered, the corresponding fault frequencies of various bearings can be obtained.
The first stage is the budding stage when the bearing begins to fail. At this time, the temperature is normal, the noise is normal, the total vibration speed and frequency spectrum are normal, but the total amount of peak energy and frequency spectrum have symptoms, 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 is slightly increased, the total vibration speed is slightly increased, and the vibration spectrum does not change significantly, but the peak energy has a large increase, and the spectrum is more prominent. The bearing failure frequency at this time appears in the range of about 500hz-2khz.
In the third stage, the temperature is slightly increased, the noise can be heard, the total vibration velocity has a great increase, and the bearing fault frequency and its harmonics and sidebands are clearly visible on the vibration velocity spectrum, and the noise level on the vibration velocity spectrum is obvious. As it increases, the total amount of peak energy becomes larger and the spectrum is more prominent compared to the second stage. The bearing failure frequency at this time occurs in the range of about 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 that can be seen with the naked eye should have already appeared.
In the fourth stage, the temperature increases significantly, the noise intensity changes significantly, the total vibration velocity and vibration displacement increase significantly, and the bearing fault frequency on the vibration velocity spectrum begins to disappear and is replaced by a larger random broadband high-frequency noise horizon; The total amount of peak energy increases rapidly, and there may be some erratic changes. Bearings must never be allowed to operate in the fourth stage of failure development, or catastrophic failure could occur.
According to the research results, in general, if the entire service life of the rolling bearing is from the time the bearing is installed and put into use, within its first >80% life time period, the bearing is all normal. Then, corresponding to the development of rolling bearing failures, the remaining life is 10% to >20% L10 in the first stage, 5%-10% L10 in the second stage, 1% ~ 5% L10 in the third stage, and about 5% in the fourth stage. For 1h or 1%L10.
Therefore, when faced with bearing problems in actual work, considering that the fourth stage of the development of bearing failures has unforeseen sudden hazards, it is recommended to replace the bearings in the later stage of the third stage, which can avoid the expansion of failures and more serious accidents. It is more convincing according to the characteristics of rolling bearing faults such as wear and parts damage that can be seen on the bearing at this time. As for the identification of bearing fault development in the later stage of the third stage, it needs to be comprehensively considered based on the above theoretical characteristics and combined with the actual temperature, noise, speed spectrum, peak energy spectrum, total trend of speed and peak energy and practical experience.