Research Of Fault Diagnosis Instrument For Gearbox Based On Vibration Signal Analysis

Gearbox is a common transmission part and critical component of mechanical equipment which is used to change running speed and power transmission in various mechanical equipment, and is prone to produce fault, so it has important practical significance to gearbox fault diagnosis. Virtual instrument technology is a idea that using computer software to replace hardware by using software algorithms to achieve the functions of instruments, it is the result of computer technology and testing technology combined. With gearbox diagnostic technique combined with virtual instrument technique, gearbox fault diagnostic instrument is developed based on virtual instrument technology and method of Gearbox vibration signal analysis.Firstly the current technology background and the developing state of the gearbox fault diagnosis at home and abroad is discussed in order to clear the aims and significance of the issue. And then, from gearbox composition structure, it analyzes the main components failure mode and the characteristics of vibration signal using vibration mechanism of gear rolling bearings and axis. The third chapter analyzes vibration signals of gearbox from the time domain, frequency domain and time-frequency domain , feature parameters and waveform in the time domain are introduced for a simple fault diagnosis, in the frequency domain amplitude spectrum, ZFFT and envelope spectrum are introduced, in the time-frequency domain Gabor transform, wavelet analysis and wavelet packet analysis are introduced. According to the fault characteristics of signal, it has to select the effective diagnostic method. Surveillance of frequency band energy of wavelet packet decomposition is introduced in gearbox fault diagnosis, and a phase difference method is introduced in order to improve the accuracy of the fault diagnosis in fault diagnosis system. The fourth chapter introduces the design process of fault diagnosis based on virtual instrument, describes the hardware system, including selection of sensor and arrangement of measuring point location and selection of signal conditioning instrument and data acquisition card, and then introduces the design ideas and flows of the main part of the software system that includes system management module, the data acquisition module, signal processing module, data management module and auxiliary function module and its experiment verification.Finally, according to characteristics of the gearbox, the gearbox fault diagnostic instrument is developed which is useful and its operation is simple, then tests the function of its each part through the experiment, the results prove that diagnostic instrument can diagnose typical fault of gearbox, and show the feasibility and effectiveness of gearbox fault diagnostic instrument.