Rolling bearings in the gear box fault how to judge?

by:J&T     2020-07-01
Bearing is a commonly used components, mechanical equipment running in gear box bearing failure how to judge and solve? A, clear internal structure and gear box bearing fault characteristics to know the basic structure of gear box, such as what kind of mode, transmission shaft gear several, what are the bearings on each shaft and what type of bearing, etc. Because you know what high-speed shaft and gear is overloaded, can help to determine the measuring point arrangement; Know the number of teeth on the motor speed and the transmission gears, transmission ratio, can help to determine the frequency of each transmission shaft. In addition, but also clearly the characteristics of the bearing fault. Under normal circumstances, the gear mesh frequency is a multiple of that of the gear and the switch frequency, and the bearing fault characteristic frequency is not a multiple of that of the switch frequency. Clear internal structure and gear box bearing fault characteristics of gear box is correct analysis of the primary premise of rolling bearings' faults. Second, as far as possible from the horizontal, vertical and axial direction to measure the selection of vibration measuring point to both axial and horizontal and vertical direction, not necessarily all position must carry on the three directions of vibration measuring. Such as gear box with heat sink, its input shaft measuring point is not convenient detection. Even some set in the intermediate position of the shaft bearing, parts in the direction of vibration is not convenient, can be selectively set point direction at this time. , but the important part of the generally must carry on the three directions of vibration measurement, pay special attention to don't ignore the axial vibration measuring, because the gear box fault will cause a lot of axial vibration energy and frequency variation. Multiple sets of vibration in addition, the same station data can also analyze and judge where the shaft speed to provide enough data for reference, and for which the further diagnosis of bearing failure to be more serious and get more reference. Three, as far as possible in each transmission shaft in the bearing on the measured vibration in gear box shell on different positions of measuring point, due to the different signal transmission path, and respond to the same incentives also differ. Gearbox transmission shaft in the bearing on bearing vibration response is sensitive, here to install monitoring stations can be well receiving bearing vibration signal, and in the upper shell is near the gear meshing point, facilitate the monitoring of other gear fault. Four, pay attention to the analysis of side band frequency for low speed, large equipment rigidity, when the gear box bearing wear, often bearing fault characteristic frequency of the vibration amplitude is not and that, but with the development of bearing wear faults, bearing fault characteristic frequency harmonics will appear a lot of, and around these frequencies will be a lot of side band. The occurrence of these situations, show that the serious fault of the bearings, need to be replaced in a timely manner. Five, give attention to both high and low frequency vibration natural frequency are included in the gearbox vibration signals, frequency of the rotation of the shaft, gear meshing frequency, bearing fault characteristic frequency, frequency composition such as the family, its frequency band is wide. To this kind of broadband frequency components of the vibration monitoring and diagnosis, normally according to frequency band classification, and then according to the different frequency range to choose corresponding measuring range and sensor. Low-frequency acceleration sensor is generally selected as low frequency, high frequency can be used in standard acceleration sensor. Six, relating to both spectrum analysis data in figure when the gear box failure occurs, sometimes the failure with the spectrum characteristics of vibration amplitude will not have big change, unable to judge fault severity or intermediate shaft rotation speed, the accurate value of figure but in the time domain analysis is done via the impact frequency failure is obvious or the drive shaft rotation speed is correct. Therefore, to accurately determine each drive shaft rotation speed or frequency of a failure, all need to combine both vibration spectrum chart and time domain chart. Special frequency to determine the abnormal harmonic frequency race, but also inseparable from the auxiliary analysis of time domain graph. In the condition of gear at full capacity, measuring vibration under full load measuring gear box, can clearly capture the fault signal. Sometimes, in low load and part of the bearing fault signal will be submerged by other signal gear box, or by other signal modulation and not easy to find. In bearing fault, of course, more serious when, at low load, is through the velocity spectrum is able to clearly capture the fault signal.
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