Research On Condition Monitoring And Off-line Analysis System Of Gearbox Based On Virtual Instrument

In mechanical equipment,Gearbox is a universal component used for connecting and transmitting power,has been widely used in all walks of life.At the same time,Gearbox is also the key components of oil,metallurgy,chemical industry,fan,aviation and other machinery and equipment.With the vigorous development of computer technology,more and more industrial production will be combined with it.The theory of gearbox of status monitoring and fault diagnosis was combined with the software programming mechanism of computer virtual instrument,which could give full play to their strengths and advantages and has a very significant value of engineering applications.Therefore,it is imperative to energetically promote the research of condition monitoring and off-line analysis system of gearbox based on virtual instrument.The main contents of this thesis include:1)In order to solve a large number of problems of noise signal interference in the vibration signal of gearbox,the basic principle of pre-Processing in the time domain and denoising method and the analysis method of vibration signal were elaborated in this paper.The denoising method of vibration signal include:the FFT forced denoising method,the auto-correlation denoising method,the wavelet forced denoising method by setting the high frequency coefficient to zero and the wavelet threshold denoising method.The the analysis method of vibration signal include:the time domain analysis,the frequency domain analysis and time-frequency joint analysis.Finally,the comparison and analysis of the simulation signal experiment were carried out by using the above four kinds of denoising methods under the conditions of the low signal to noise ratio and high signal to noise ratio,and the applicable occasions and adaptation conditions were summed up by using the different denoising methods.2)comparing to several basic structures of gear box test-bed,the gear box condition monitoring test-bed with the opened power structure was set up.The temperature test scheme,the box vibration test scheme,the shaft vibration test scheme,the speed and torque test scheme were designed.The selection of hardware and the layout of test points were completed.The electrical control circuit of the test system in the form of electrical control cabinet were designed,which ensures the operation safe in the course of the gear box working.The research on condition monitoring and off-line analysis system of gearbox were laid the foundation by the construction of gearbox test platform.3)The software design of condition monitoring and off-line analysis system of gearbox were set up by using the mixed programming method of Lab VIEW and MATLAB.The condition monitoring system include:the monitoring system of temperature,speed and torque,the monitoring system of box vibration,the monitoring system of shaft vibration and the system of data storage.The off-line analysis system were mainly used to.analyze the vibration signal,it includes:the characteristic frequency calculation module,the time domain analysis module,the FFT analysis module,the cepstrum analysis module,the refinement spectrum analysis module,the delay correlation demodulation analysis module,the wavelet decomposition envelope analysis module,noise source analysis module and time-frequency joint analysis module.4)Real-time monitoring and off-line analysis about the current running state and historical running status of the gearbox been respectively carried out by using the software system based on the gearbox condition monitoring test-bed The no-load test and the loading test were designed in order to in real time monitor the 16-channel signal of the gearbox and store the data.The results showed that the parameters are basically in the standard values within the specified range.Via the off-line analysis of the stored test data,fault type of gearbox could been prejudged.Finally,the fault data from the bearing data center of the Western Reserve University is used for verifying the adaptability of the off-line analysis system to the bearing failure analysis.