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Practical skills to teach you a few rolling bearing fault diagnosis

Application of rolling bearing in the device is very extensive, rolling bearing status is directly related to the operation state of rotating equipment, especially in continuous production enterprises, a large number of large rotating equipment used in the important parts, therefore, the actual production for rolling bearing condition monitoring and fault diagnosis is an important part of equipment maintenance and management. We through the long-term practice and exploration, and accumulated some practical skills for the actual fault diagnosis of rolling bearing.
A rolling bearing fault diagnosis approach and key points
The practical method of rolling bearing condition monitoring and fault diagnosis is vibration analysis.
Should pay attention to choose the position of the measuring points and the acquisition method of practical. To accurately reflect the state of rolling bearing vibration real, must pay attention to the collected signal accurately, so in the nearest place from bearing arrangement of measuring points, at the free end are generally after the motor fan cover, the choice point in the fan cover fixing screw has better monitoring effect. It should also be noted on the vibration signal acquisition and analysis for many times, the comprehensive comparison. To obtain accurate conclusion.
Two, the rolling characteristics and practical diagnostic skills and the normal operation of the bearing
We in the long-term production found in condition monitoring of rolling bearings show strong regularity in the course of its use, and the repeatability is very good. High quality bearing used in the beginning, vibration and noise are relatively small, but some scattered spectrum, amplitude is smaller, may be due to some defects in the manufacturing process, such as surface caused by burr etc..
The campaign for a period of time, to maintain a certain level of vibration and noise, the spectrum is very single, only appeared one or two times. Rarely appears three times above the frequency spectrum, bearing condition is stable, entered the period of stable work.
Continue running after entering the use of late, the vibration and noise of rolling bearings has started to increase, sometimes appear abnormal sound, but changes the vibration increase more slowly, at this time, bearing kurtosis value suddenly reaches a certain value. We think, this time bearing which shows the initial fault.
At this time, requires close monitoring of the bearing, pay close attention to the change of. Since then, bearing kurtosis value began to decline rapidly, and close to the normal value, and the vibration and the noise began to significantly increased, the increase amplitude was accelerated when vibration more than vibration standards (such as ISO2372 standards), the bearing kurtosis value began to increase quickly, when both exceeding vibration standard, and kurtosis value more than the normal value (available kurtosis relative standard), we believe that the bearing has entered advanced fault property, the need for timely maintenance equipment, replacement of rolling bearing.
Bearing showed advanced fault feature to appear serious fault (usually bearing damage such as axle, burns, sand frame spallation, raceway, beads to wear) most of the time not more than a week, equipment greater capacity, higher speed, the interval time is short. Therefore, in the actual fault diagnosis of rolling bearing, once found late fault characteristics, should be decisive judgment bearing fault, arrange the repair as soon as possible.
Three, rolling bearing abnormal operation characteristics and diagnostic skills
Now because of counterfeit bearings will inevitably enter the enterprise and equipment, serious fault and the floating bearings cause is often sudden, catastrophic. If the bearing cage suddenly fracture, bearing inner and outer ring deflagration fracture, these faults will cause the rotor axle, even lead to the rotor or equipment scrapping. In recent years we are in practice often encounter this kind of situation. Therefore, in the actual monitoring and diagnosis, as soon as possible to diagnose the rolling bearing status is good or bad, and timely replacement of counterfeit bearings, avoid accident. We are in a large number of such incidents, but also accumulated some practical skills, is this kind of bearings operating in early after installation, monitoring its vibration state, and spectral analysis. We found that the bearing at the beginning, the spectrum has its unique characteristics, namely the equipment power frequency is generally not accounted for the major ingredients. But with little vibration gross, vibration standards (such as ISO2372 standards) diagnosis of vibration is qualified.
At this time, will cause our vigilance, the condition that the performance of bearing component defects, its failure is often very fast and very suddenly. The above example is finish this picture in two hours after the rotor axle.
In the diagnosis of these fake bearing fault, and to pay more attention to the accumulation of normal peacetime operation quality bearings in the equipment vibration spectrum and time domain, convenient in such abnormal spectrum can timely judge the bearing fault, to avoid the accident of the equipment.
Rapid diagnosis technique of rolling bearing, the utility of the four
In our actual condition monitoring, often only to judge the quality of rolling bearing, for how long, and the precision analysis and diagnosis of bearing fault diagnosis of a site often is not practical. Precise diagnostic utility because of the conditions and other factors, often can not find the corresponding characteristic frequency of rolling bearing. Although wavelet analysis in recent years with the rapid development of common vibration demodulation analysis technique is more accurate, but the equipment required greater investment, also need more analysis, fault diagnosis is seldom used on site staff. We take a dimensionless parameters and dimensionless parameters in combination with the judgment of bearing fault quick diagnosis in practical diagnosis, namely uses the frequency spectrum analysis of vibration speed, combined with comprehensive diagnosis of bearing kurtosis value. When two conditions are more than standard, we judge the existence of bearing fault.
This method of judgment after three years of practice, proved to be very useful for the fault diagnosis of rolling bearing

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