Research On Fault Feature Extraction Of Planetary Gearbox Torsional Vibration Signal

Planetary gearbox with a large transmission ratio,small size,carrying capacity,work stability and many other advantages,widely used in aviation,wind power and other mechanical transmission systems,planetary gearbox is closely related to the working efficiency of the mechanical equipment during its operation.However,due to the long-term operation of the planetary gearbox in harsh environments with high strength and high load,mechanical faults such as fatigue cracks and gear wear easily occur.Therefore,research on the field of fault diagnosis of planetary gearboxes is of great significance.It can diagnose faults in advance,improve the service life of devices and prevent unexpected faults.Therefore,this paper studies the fault feature extraction of planetary gearboxes based on torsional vibration signals.The main contents are as follows:The measurement method of acquiring torsional vibration signal based on the incremental encoder installed on the planetary gearbox is proposed and implemented.The multi-function data acquisition card and high-resolution encoder are selected by the principle of high-frequency pulse counting,improve the corresponding planetary gearbox software data acquisition system,and then add the required hardware configuration,build a complete planetary gearbox fault diagnosis experimental platform.The spectrum characteristics of the torsional vibration signals of planetary gearbox are introduced.The feasibility of the torsional vibration signal is analyzed through experiments.Compared with the transverse vibration signal,the torsional vibration signal has the advantages of simple spectral structure,high signal-to-noise ratio,less susceptible to other vibration sources and being sensitive to the fault,so as to determine the torsional vibration signal as an experimental analysis signal of the planetary gearbox fault diagnosis.The torsional vibration signals of the input shaft and the output shaft of the planetary gearbox under no-load and under different loads are studied respectively.The contrastive analysis is made between the normal state and the broken tooth state respectively,it is considered that the torsional vibration signal of the input shaft is more sensitive than the output shaft to the fault when the planetary gear box is in no-load operation,which can better reflect the fault characteristics.When the load is changing,it is found that the output shaft torsional vibration signal has more advantages than the input shaft and is more sensitive to the fault characteristics,just the opposite of the no-load condition.At the same time,the fault diagnosis from the perspective of fault characteristics indicators,respectively,comparative analysis of kurtosis and root mean square value before and after the change,the occurrence of both diagnosis is better.Aiming at the fault feature extraction of planetary gearbox in harsh environment,a time-domain analysis method of torsional vibration signal based on H-P filtering combined with variational mode decomposition is proposed.Firstly,the method is verified by constructing analog signals,and then the feasibility of this method is further demonstrated under different loads by means of experiments,the experiment also judges the occurrence of the fault from the change of kurtosis index before and after the torsional vibration signal processing,and solves the problem that the fault feature of the torsional vibration signal of the input shaft of the planetary gearbox is not obvious when the load is loaded.