Gearbox Fault Diagnosis Strategy
Release date:
2022-01-22
A gearbox is an industrial component that facilitates power transmission through a system of meshing gears. At the same time, as a mechanical accessory for transmission gears, gearboxes have found extensive applications in the chemical industry. This discussion, combined with real-world applications of gearboxes, elaborates on the common failure symptoms of gearboxes and outlines effective diagnostic measures to address them.
Gearbox It is an industrial component that can perform the task of power transmission through a system of drive gears. At the same time, Gearbox As mechanical accessories for transmission gears, they have also found widespread application in the chemical industry. Combined with Gearbox The application provides a detailed discussion of the typical symptoms of gearbox failures and the corresponding diagnostic measures.
Gearbox It is a unified mechanical system where gears and bearings coexist. Various failures caused by manufacturing defects or excessive pressure deserve attention. Generally, the following methods are commonly employed:
1. Cepstral Analysis Method
Cepstral analysis, also known as second-order spectral analysis, is a cutting-edge technique in modern signal processing science. When the spectrum of a mechanical signal contains multiple modulation side frequencies that are difficult to identify individually, cepstrum analysis can decompose and isolate the fault-related frequency components, enabling a detailed diagnosis of the underlying cause of the malfunction.
For multiple pairs of gears meshing with each other Gearbox Vibration spectrum diagrams reveal sidebands with each gear meshing. When individual sidebands overlap and are densely distributed, frequency refinement for identification and analysis becomes insufficient. This is because the cepstrum transforms the harmonics in the power spectrum into a single spectral line in the cepstral domain, where the position of this line directly corresponds to the time-separated harmonic frequencies present in the original power spectrum.
Another significant advantage of the cepstrum is that it is insensitive to the sensor’s signal transmission path or the orientation of the measurement point, and it also remains unaffected by the correlation between frequency modulation and amplitude values. In turn, this makes it easier to monitor the magnitude of fault signals without needing to measure the exact amplitude values at the specific measurement point.
2. Sideband Analysis Method
Generally, sideband analysis is conducted from two perspectives: first, by comparing the range of sideband amplitude variations across different measurement processes; and second, by leveraging the symmetric properties of sideband frequencies to examine specific frequency relationships, helping determine whether they belong to the same set of sidebands. If they do, the frequency value of the modulating signal can be determined. Gearbox The meshing frequency.
It should be noted that individual faults—such as gear detachment, root cracks, and isolated tooth breakage—typically exhibit distinct transient modulation, producing a series of sidebands both in the meshing direction and on either side. These sidebands are primarily characterized by their dense, orderly, yet dispersed spectral lines. Additionally, due to the stacking of higher-order frequency modulators, the shape of the side frequencies varies. Furthermore, when significant localized faults occur, they can also lead to an increase in harmonic components as well as their rotational frequencies.
The sideband component here contains sufficient Gearbox Fault information resources. To obtain this information, sufficient frequency resolution is required during spectrum analysis, enabling accurate measurement of the distance between sidebands.
3. Power Spectrum Analysis Method
The power spectrum is a statistical averaging concept for random processes, and for a stationary random process, the power spectrum is a fixed function. This method allows us to determine Gearbox The frequency components of the vibration signal and the distribution of vibrational energy across each frequency. Since the power spectrum is proportional to the square of the amplitude, it emphasizes the linear spectral components of harmonics and meshing frequencies compared to the amplitude spectrum, while also reducing the series of "burrs" caused by the vibration signal.
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