How to determine whether the bearing can be reused
Bearing is an important part of modern mechanical equipment. Its main function is to support the mechanical rotating body, reduce its friction coefficient and ensure its rotation accuracy.
Bearing plays such an important role in mechanical equipment, so the number of bearings used is also very large. How to better play the role of bearings, the need for correct and reasonable use. In the process of bearing use, some bearings will be removed when the equipment is regularly overhauled, inspected for operation and replaced for peripheral parts. Whether these removed bearings can be used again requires inspection, investigation and recording of bearing appearance. At the same time, in order to clarify and investigate the remaining amount of lubricant, after sampling, the bearing should be better cleaned.
1、 Inspection of removed bearing
Firstly, check the condition of raceway surface, rolling surface and mating surface, as well as the wear condition of cage for damage and abnormality.
Furthermore, considering the degree of bearing damage, machine performance, importance, operating conditions, inspection cycle, etc., we can decide whether the bearing can be reused or replaced. If the bearing is found to be damaged and abnormal, find out the causes and formulate countermeasures. If there are the following defects, the bearing can no longer be used and can be scrapped directly.
1. Any one of the inner and outer rings, rolling element and cage has cracks and debris.
2. Any one of the inner and outer rings or rolling elements has peeling.
3. The raceway surface, rib and rolling element are obviously jammed.
4. The cage is seriously worn or the rivet is loose.
5. Rust and scar on raceway surface and rolling element.
6. The rolling surface and rolling element have obvious indentation and marking.
7. Having creep on the inner surface of the inner ring or the outer surface of the outer ring.
8. It's very hot.
9. The seal ring and dust cover of grease seal bearing are damaged seriously.
2、 Determination of bearings in operation
How to determine whether there is a problem in the running bearing can be determined by checking the rolling sound, vibration, temperature, lubrication state of the bearing.
（1） Rolling sound of bearing
The size and sound quality of the rolling sound of the running bearing are checked by using a sound detector. Even if the bearing has slight peeling and other damage, it will emit abnormal sound and irregular sound, which can be distinguished by the sound detector.
（2） Vibration of bearing
Bearing vibration is very sensitive to bearing damage, such as peeling, indentation, corrosion, crack, wear and so on, which will be reflected in the bearing vibration measurement. Therefore, by using a special bearing vibration measuring device (frequency analyzer, etc.), the vibration size can be measured, and the specific situation of abnormality can be inferred from the frequency. Therefore, the measured values of each machine need to be compared and analyzed according to different installation conditions.
（3） Temperature of bearing
Generally, the temperature of the bearing rises slowly with the operation and reaches a stable state after 1-2 hours. The normal temperature of the bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are suitable, the bearing temperature will rise sharply, and abnormal high temperature will appear. At this time, the operation must be stopped and necessary preventive measures must be taken. The working temperature of the bearing can be monitored at any time by using the thermal sensor, and the automatic alarm or stop can be realized when the temperature exceeds the specified value, so as to prevent the shaft burning accident.
（4） Lubrication status of bearings
Lubrication is of great significance for rolling bearings. The lubricant in bearings can not only reduce the friction resistance, but also play the role of heat dissipation, reducing contact stress, absorbing vibration and preventing corrosion. It is also the necessary condition for rolling bearings to work stably.