Summary of the means of analyzing various types of fault vibration signals of gearboxes
The various faults of the gearbox have typical characteristics in the time domain waveform. From the time domain waveform analysis, you can get three kinds of fault information, the type of the real-time domain function (deterministic or random), and the frequency component in the waveform. Whether it is complicated; whether the amplitude of the vibration changes, and how the law changes; whether there is obvious impact and modulation component in the waveform. For the fault diagnosis of the gearbox, the meshing frequency is a prominent component of the gear vibration. It is a sensitive indicator of the gear tooth profile wear. At the same time, it will cause pitting, peeling and other damage on the tooth surface, as well as gear breakage, gluing and other faults. It is expressed in the meshing frequency and its harmonic components.
Gear failure spectrum and waveform characteristics
1) The faulty gear has a large vibration component at the meshing frequency and its harmonic frequency.
2) Modulation of the sidebands around the meshing frequency and its harmonic components.
★The modulation frequency represented by the sideband spacing can be
a) the speed of each axis (input shaft, output shaft, intermediate shaft);
b) the fluctuation frequency of the external speed or load;
c) Fluctuating meshing frequency. That is (intermeshing frequency) / (the least common multiple of the speed of the driving gear and the driven gear)
d) If there are more than two faults at the same time, the sum or difference of the fault frequencies can also be the modulation frequency, called the intermediate frequency.
3) For helical gears, helical gears and herringbone gears, the axial vibration is large and the spectral characteristics are the same as the radial vibration.
Tip: Because the spectrum analysis of the gearbox is more complicated, it is difficult to identify. An effective and feasible method is to collect the reference spectrum for each gear box in a good working condition, and to find the problem by comparing with the reference spectrum in condition monitoring and fault diagnosis.