Effect of Angular Contact Ball Bearing Checking on Use
Clicks：7552018-12-12 17:32:21
Shaft parts of machine tools, especially spindles, are generally assembled with thrust ball bearings and rotate at high speed, sometimes producing high heat. If this phenomenon is not eliminated in time, it will lead to overheating of angular contact ball bearings and thermal deformation resulting from the rise of temperature in the corresponding parts of the machine tool. In serious cases, it will make the spindle and tailstock unequal in height, which will not only affect the accuracy of the machine tool itself and processing accuracy, but also burn the bearing.
Rated fatigue life refers to the total number of rotations in which a group of bearings of the same type will operate under the same conditions, and 90% of the angular contact ball bearings will not appear the spalling caused by rolling fatigue. When the speed is constant, the rated fatigue life is usually expressed by the total running time.
When studying the life of thrust ball bearings, we should not only consider the fatigue life, but also consider the performance of thrust ball bearings according to several limits of use. For example, the grease life of Grease-Lubricated bearings. Noise life, wear life and so on, depending on the use of different, the use limit benchmarks are different, so most of them choose the experience limit in advance.
Therefore, only investigating the damage of angular contact ball bearings, it is difficult to know the real cause of the damage. However, if we know the use of thrust ball bearing machinery, operating conditions, the structure around the bearing, understand the situation before and after the accident, combined with the bearing damage status and several reasons, we can prevent similar accidents from happening again.
Whether angular contact ball bearings can be used or not is mainly determined by considering the degree of bearing damage, mechanical properties, importance, operating conditions and the period to the next overhaul. New thrust ball bearings must be replaced if the following defects are not available. There are cracks or notches in either inner ring, outer ring, rolling element or cage.
Wear failure is one of the common failure modes of all kinds of bearings. According to the wear form, it can be divided into the most common abrasive wear and adhesive wear.
1. Diagnostic technology of oil film resistance
Characteristics: The same criterion can be used for different working conditions. It has poor diagnostic effect on surface exfoliation, indentation, crack and other abnormalities.
Scope of application: It is suitable for the occasion where the rotating axle is exposed.
2. Vibration Diagnosis Technology
Features: Vibration diagnosis technology is widely used, online monitoring can be realized, diagnosis is fast, diagnosis theory has matured.
Application Range: It is especially suitable for fault monitoring of angular contact ball bearings in rotating machinery.
3. Ferrographic diagnostic techniques
Features: No disintegration of the machine; low investment, good results; can find the early fatigue failure of oil-free bearings; can do wear mechanism research.
Scope of application: It is suitable for fault diagnosis of angular contact ball bearings lubricated with lubricating oil, but difficult for bearings lubricated with grease.
4. Temperature Diagnosis Technology
Characteristic: The diagnosis is simple, and the effect of judging bearing burn is good.
Scope of application: It is suitable for simple and routine diagnosis of bearings in machines.
5. Optical Fiber Monitoring and Diagnosis Technology
Features: Optical fiber displacement sensor has high sensitivity; it can directly extract signals from the surface of oil-free bearings to improve signal-to-noise ratio; it can directly reflect the manufacturing quality, surface wear degree, load, lubrication and clearance of angular contact ball bearings.
Scope of application: Suitable for machine which can install sensor in bearing seat.
6. Acoustic Emission Diagnosis Technology
Characteristics: The diagnosis is fast and simple, and can be monitored online.
Scope of application: The new technology developed in recent years has less application in bearing condition monitoring.
When taking oil-free bearings directly by hand, sweat on hands should be thoroughly washed, and high-quality mineral oil should be applied before operation. In rainy season and summer, special attention should be paid to rust prevention. Under some special operating conditions, angular contact ball bearings can obtain longer life than traditional calculation, especially under light load. These special operating conditions are that when the rolling surface (track and rolling parts) is effectively separated by a lubricating oil film and the contaminants may cause surface damage. In fact, under ideal conditions, the so-called life of permanent bearings is possible.
Strong stamping, hammer tapping and pressure transfer through the rolling element are not allowed.
When angular contact ball bearings rotate, the raceway surface of inner ring and outer ring is in rolling contact with the rolling body, so the running track is dark, and the running track attached to the raceway surface is not abnormal, so the load conditions can be known. So when disassembling oil-free bearings, please pay close attention to and observe the running track of the raceway surface.
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