Failure judgment of angular contact ball bearing
Whether the angular contact ball bearing can be used is mainly determined by considering the damage degree, mechanical properties, importance, operation conditions and the next maintenance period. If there are the following defects, it can not be used any more, and the thrust ball bearing must be replaced with a new one. There are cracks or notches on any one of the inner ring, outer ring, rolling element and cage. Wear failure is one of the common failure modes of all kinds of bearings, which can be divided into the most common abrasive wear and adhesive wear. We can judge whether the bearing has reached wear failure by the following technologies:
1. Oil film resistance diagnosis technology
Features: the same evaluation standard can be used for different working conditions. The results of diagnosis of surface peeling, indentation and crack are poor
Application scope: it is suitable for the occasion where the rotating shaft is exposed.
2. Vibration diagnosis technology
Features: vibration diagnosis technology is widely used; online monitoring can be realized; diagnosis is fast and diagnosis theory is mature.
Application scope: it is especially suitable for fault monitoring of angular contact ball bearing in rotating machinery.
3. Ferrography diagnosis technology
Features: the machine does not need to be disassembled; the investment is low and the effect is good; the early fatigue failure of oil-free bearing can be found; the wear mechanism can be studied.
Application scope: it is suitable for the fault diagnosis of angular contact ball bearing lubricated with lubricating oil, and it is difficult for bearing lubricated with grease.
4. Temperature Diagnosis Technology
Features: the diagnosis is simple, and the effect of judgment is good.
Scope of application: it is suitable for simple conventional diagnosis of bearings in machines.
5. Optical fiber monitoring and diagnosis technology
Features: high sensitivity of optical fiber displacement sensor; direct extraction of signal from oil-free bearing surface to improve the signal-to-noise ratio; can directly reflect the manufacturing quality, surface wear, load, lubrication and clearance of angular contact ball bearing.
Application scope: suitable for the machine that can install the sensor in the bearing seat.
6. Acoustic emission diagnosis technology
Features: rapid and simple diagnosis, on-line monitoring.
Application scope: the new technology developed in recent years is seldom used in bearing condition monitoring.
In the process of testing, when the oil-free bearing is directly taken by hand, the sweat on the hand shall be fully washed off, and the operation shall be carried out after the application of high-quality mineral oil. In rainy season and summer, special attention shall be paid to rust prevention. Under some special operating conditions, the life of angular contact ball bearing can be longer than that of traditional calculation, especially under light load. These special operating conditions are when the rolling surface (track and rolling element) is effectively separated by a lubricating oil film and limits the possible surface damage caused by pollutants. In fact, under ideal conditions, the so-called permanent bearing life is possible.
When the angular contact ball bearing rotates and the raceway surface between the inner ring and the outer ring is in rolling contact with the rolling body, the running track is a dark surface. The running track attached to the raceway surface is not abnormal, so the load conditions can be known. Therefore, when disassembling the oil-free bearing, please pay close attention to and observe the running track of the raceway surface.
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