Torsional Vibration Signal Measuring And Fault Diagnosis Of Planetary Gear Box

Planetary gear transmission is the key mechanical device of helicopter power drive system,however,a variety of failure phenomena occur to planetary gear train easily for it usually works in the harsh environment.The fault diagnosis technology for planetary gear make a lot of sense in reducing equipment maintenance costs and preventing sudden accident.At present,the transverse vibration signal is commonly used in the fault diagnosis for planetary gear.Due to the complexity of meshing relationship between planetary gear train,it is very difficult to extract meshing vibration signal of the object gear from the collected signal while it is relatively simple to extract the gear meshing vibration information from the torsional vibration signal of the gear shaft.Therefore,this paper studied the technology of the fault diagnosis for planetary gear based on torsional vibration of the gear shaft:1.This paper proposed and tested the measuring method of torsional vibration based on incremental encoder and high frequency clock pulse counting,this method belongs to a kind of contact measuring method,but the encoder is installed on the shaft through a certain way,which doesn’t destroy the original structure of machine and affect the normal operation of the machine.A set of count obtained from this method can figure out a set of angular velocity vector and time vector which can get the angular velocity-time curves of torsional vibration signal.In order to analyze this signal,we need to reconstructed the unequi-time spaced signal of torsional vibration into the equi-time spaced signal through resampling by using the algorithm of first-order linear interpolation2.Applying LabVIEW graphical programming language developed the signal acquisition system and analysis system for planetary gear box based on torsional vibration which can collect and store and process the torsional vibration signal of planetary gear.3.Exerting torque on the planetary gear box via magnetic powder brake and processing a broken teeth by means of wire cutting.Sampling the torsional vibration signal of planetary gear under the normal state and the failure state.At the same time,using the piezoelectric acceleration sensor gather the vibration signal of planetary gear box.4.It is necessary to compare the analysis of vibration signal with the analysis oftorsional vibration and conclude the correct result after analyzing the torsional vibration signal in time domain,frequency domain,time-frequency domain,normalized energy spectrum based on wavelet packet transform and processing the vibration signal of planetary gear box under the fault state in the spectrum at the same time.The experimental conclusion illustrated that the torsional vibration signal is more sensitive to fault, the frequency ingredient of the torsional vibration signal is clearly visible in the spectrum,it can effectively reflect the characteristics of the planetary gear fault,it is advantaged to apply the torsional vibration signal to the fault diagnosis for planetary gear.