The shaft parts of the machine tool, especially the main shaft, are generally assembled with the thrust ball bearing and rotate at a high speed, sometimes generating high heat. If this phenomenon is not eliminated in time, it will cause the angular contact ball bearing to overheat and cause the temperature of the corresponding part of the machine tool to increase and cause thermal deformation. In severe cases, the spindle and the tailstock will not be equal, which not only affects the precision and machining accuracy of the machine tool itself. And will burn the bearing.
Rated fatigue life refers to the operation of a group of bearings of the same type under the same conditions. 90% of the angular contact ball bearings do not have the total number of revolutions caused by rolling fatigue. When the speed is constant, the total running time is used to indicate the rated fatigue life.
When studying the life of a thrust ball bearing, it is not only possible to consider the fatigue life, but also to consider the performance of the bearing and combine several use limits. For example, the grease life of grease lubricated bearings. Since the noise life, the wear life, and the like vary depending on the application, the use limit is different, and therefore, the experience limit is often selected in advance.
Therefore, it is difficult to know the true cause of the damage by investigating only the angular contact ball bearing damage。 However, if you know the use of the thrust ball bearing machinery, the conditions of use, the structure around the bearing, and understand the situation before and after the accident, combined with the damage state of the bearing and several reasons, it can prevent similar accidents from happening again。
The judgment of the availability of angular contact ball bearings is mainly based on the degree of bearing damage, mechanical properties, importance, operating conditions, and the period of the next inspection. If you have the following defects, you can no longer use them. You must replace the new thrust ball bearings. There is a crack or a gap in any of the inner ring, the outer ring, the rolling element, and the cage.
Wear failure is one of the common failure modes for all types of bearings。 It is usually classified into the most common abrasive wear and adhesive wear in terms of wear。
1. Oil film resistance diagnostic technology
Features: The same evaluation criteria can be used for different working conditions. It has a poor diagnostic effect on abnormalities such as surface peeling, indentation, and cracks.
Application: Suitable for applications 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 diagnostic theory is mature.
Scope of application: Particularly suitable for fault monitoring of angular contact ball bearings in rotating machinery.
3。Metal Spectrum Diagnosis Technology
Features: The machine does not need to be disassembled; the investment is low, the effect is good; the early fatigue failure of the oil-free bearing can be found; the wear mechanism can be studied。
Scope of application: For the diagnosis of angular contact ball bearings lubricated with lubricating oil, it is difficult for grease-lubricated bearings.
4。 Temperature diagnostic technology
Features: Simple diagnosis; better judgment on bearing burns.
Scope of application: Simple routine diagnostics for bearings in machines。
5。 Fiber-optic monitoring and diagnostic technology
Features: High sensitivity of fiber-optic displacement sensor; direct extraction of signal from oil-free bearing surface, improved signal-to-noise ratio; direct reflection of angular contact ball bearings Manufacturing quality, surface wear, load, lubrication and clearance。
Application: Suitable for machines where the sensor can be mounted in a housing.
6. Acoustic emission diagnostic technology
Features: Quick and easy diagnosis; online monitoring.
Scope of application: New technologies developed in recent years have been used less in bearing condition monitoring.
When taking oil-free bearings directly by hand, wash off the sweat on your hands and apply high-quality mineral oil before handling. Pay special attention to rust prevention during the rainy season and summer. Under certain special operating conditions, angular contact ball bearings can achieve longer life than conventional calculations, especially at light loads. These special operating conditions are when the rolling surfaces (tracks and rolling elements) are effectively separated by a lubricating film and the surface damage caused by contaminants is limited. In fact, under ideal conditions, the so-called permanent bearing life is likely to not allow strong stamping, does not allow the hammer to directly hit the bearing, and does not allow pressure to be transmitted through the rolling elements.
When the angular contact ball bearing rotates, the raceway surface of the inner ring and the outer ring is in rolling contact with the rolling element, the running track is a dark surface, and the running track attached to the raceway surface is not abnormal. Therefore, the load condition can be known, so when disassembling the oil-free bearing, please pay close attention to and observe the running track of the raceway surface.