The purpose of simple diagnosis is to quickly determine whether the gear is in a normal working state, and to further perform precise diagnosis and analysis or take other measures for the gear in an abnormal working state. Of course, in many cases, some obvious faults can also be diagnosed based on a simple analysis of vibration. Simple diagnosis of gear includes noise diagnosis method, vibration diagnosis method and shock pulse (SPM) diagnosis method, etc. The most commonly used is vibration diagnosis method. The vibration level diagnosis method is a diagnosis method that uses the vibration intensity of the gear to determine whether the gear is in a normal working state. According to different judgment indexes and standards, it can be divided into absolute value judgment method and relative value judgment method.
Absolute Value Judgment Method
The absolute value judgment method uses the amplitude value measured at the same measuring point on the gearbox directly as an index to evaluate the running state.
To use the absolute value judgment method to identify the gear state, it is necessary to formulate corresponding judgment standards according to different gearboxes and different use requirements.
The main basis for determining the absolute value of gears is as follows:
1) Theoretical research on abnormal vibration phenomena;
(2) Analysis of vibration phenomena based on experiments;
(3) Statistical evaluation of the measured data;
(4) Refer to relevant domestic and foreign standards.
In fact, there is no absolute value judgment standard that can be applied to all gears. When the size and type of the gear are different, the judgment standard is naturally different.
When making a judgment on broadband vibration based on a measurement parameter, the standard value must be changed according to the frequency. If the frequency is below 1kHz, the vibration is judged by speed; if the frequency is above 1kHz, the vibration is judged by acceleration. The actual standard also depends on the specific situation.
Phase time value judgment method
In practical applications, for gears that have not yet established an absolute value judgment standard, you can make full use of on-site measured data to perform statistical averages and develop appropriate relative judgment standards. The use of this standard for judgment is called the relative value judgment method.
The relative judgment standard requires that the amplitude measured at the same part of the gearbox at different times is compared with the amplitude under the normal state. When the measured value is compared with the normal value to a certain degree, it is judged as a certain state. For example, the relative value judgment standard stipulates that attention should be paid when the actual value reaches 1.6 to 2 times the normal value, and it is dangerous when it reaches 2.56 to 4 times. As for the specific use, whether it is classified according to 1.6 times or 2 times, it depends on the use requirements of the gearbox. Rough equipment (such as mining machinery) generally uses a higher multiple of classification.
In practice, in order to achieve the best results, the above two methods can be used at the same time for comparison and comprehensive evaluation.
