Reseach On Fault Diagnosis Instrument Of Rolling Bearing Based On The Theory Of Resonance Demodulation

As a core component of supporting the rotor in rotating machinery, rolling bearing has a great influence on the stability and reliability of the mechanical system. State monitoring and fault diagnosis system includes on-line and off-line system. The on-line system has a high cost, difficult management and maintenance. The off-line system can not be real-time monitoring and diagnosis and hidden safety problems. Taking rolling bearing as an object, this thesis reaserches a portable, low cost, high stability, real-time monitoring and diagnosis of instrument for small and medium-sized machinery equipment.The main contents of this thesis included the related theory of rolling bearing fault diagnosis and the realization process of fault diagnosis instrument. In the theoretical study, the failure modes and characteristics of vibration signals of rolling bearings are elaborated, and the mechanism of fault generated is analyzed in the frequency domain starting from the rolling bearing structure, and the fault characteristic frequency estimation formulas are given. The fault diagnosis methods include the time-domain and frequency-domain diagnostic method. Time-domain diagnosis methods include time-domain index threshold diagnosis and vibration intensity diagnosis, they are all belong to the automatic diagnosis method. The resonance demodulation technology is selected as the frequency-domain diagnostic methods, and the principle and realization of the resonance demodulation technology are focused on. The core technologies of the resonance demodulation are demodulation technology and the determination of resonance band. The principle and realization process of Hilbert demodulation are analyzed, and the spectral kurtosis is brought into characterizing the vibration impact degree, so as to determine the optimum resonance band.The realization process of fault diagnosis instrument includes hardware and software system design. The hardware system design uses the modular design thought. According to the demand analysis, the hardware system is divided into 11 modules, and includes two core processors, which uses DSP as signal processor and CPLD as the control processor, and the principle diagram of each module is given. According to the demand analysis, the software system design is divided into 12 modules, and the key problems of the fixed-point DSP programming are analyzed, and the design thought of the module of algorithm realization is focused on, and the program flow charts and the simulation results are given.Finally, the correctness of the fault diagnosis instrument system is verified using the actual measurement vibration signal and compared with computer calculation results through MTALAB. The actual measurement vibration signal includes laboratory data and fan vibration data. The results show that the fault diagnosis instrument demodulates the fault characteristic frequency and their multiple frequencies, and accurately judges the fault location, and can effectively diagnose the faults of rolling bearing.