Practical skills for diagnosing common faults of rolling bearings
In actual production, rolling bearing condition monitoring and fault diagnosis is an important part of equipment maintenance and management. Because of the application of rolling bearings in the equipment is very extensive, rolling bearing status is directly related to the running condition of the equipment, especially in continuous production enterprises, widely used in the important parts of large rotating equipment. After a long period of practice and exploration, we have accumulated some practical skills in practical fault diagnosis of rolling bearings.
I. The method and key points of rolling bearing fault diagnosis
Vibration analysis is a practical method for condition monitoring and fault diagnosis of rolling bearings.
In practice, it is necessary to pay attention to the location and collection method of measuring points. In order to accurately reflect the true state of rolling bearing vibration signal acquisition, must be true and accurate, so to the nearest place from the bearing arrangement of measuring points in the motor free end generally after the fan cover, the choice of measurement points in the fan cover fixing screw has good monitoring effect. In addition, it is necessary to pay attention to the vibration signal collection and analysis, and make a comprehensive comparison. To arrive at an exact conclusion.
Two, rolling bearing normal running characteristics and practical diagnostic skills
We found in the long-term production status monitoring, rolling bearings in its use process shows a strong regularity, and repeatability is very good. When the normal high quality bearings begin to use, the vibration and noise are relatively small, but the spectrum is scattered and the amplitudes are small. It may be due to some defects in the manufacturing process, such as surface burrs.
After a period of movement, vibration and noise maintain a certain level, the spectrum is very single, only one or two octave. Rarely appear three times more than the frequency spectrum, the bearing state is very stable, into a stable working period.
In the later stage of operation, the vibration and noise of bearing begin to increase, sometimes abnormal sound occurs, but the vibration increases slowly. At this time, the value of bearing kurtosis begins to reach a certain value suddenly. We think that the bearings at this point represent incipient faults.
At this time, it requires close monitoring of the bearing, pay close attention to its changes. Since then, bearing kurtosis value began to decline rapidly, and close to the normal value, while the vibration and noise began to increase, the increase rate began to accelerate, when the vibration vibration exceeds standard (ISO2372 standard), the bearing kurtosis value began to increase rapidly, when both exceed the vibration standard, and kurtosis value of more than the normal value (available kurtosis relative standard), we believe that the bearing has entered the late fault, the need for timely maintenance of equipment, replacement of rolling bearings.
The bearing showed late fault features to a serious failure (usually bearing damage such as axle, burn, sand spallation, raceway, wear beads etc.) most of the time not more than a week, equipment capacity larger, higher speed, shorter intervals. Therefore, in the actual rolling bearing fault diagnosis, once the late fault characteristics are found, the bearing shall be determined and the repair shall be arranged as soon as possible.