The Application Of Fractal Theory In Fault Diagnosis Of Rolling Bearing In Gear Box

In modern production, condition monitoring and fault diagnosis of mechanical equipment system are of great significance and has being paid more and more attention to, for it has great economical and engineering values. In recent years, many scholars have made a lot of job on it, and put up some new methods and technologies of fault diagnosis. It is a new trend that fractal theory is applied in the field of machinery fault diagnosis. By means of fractal theory, the running state of the system can be analyzed not only qualitatively but also quantitatively, and then the faults of complex machinery system can be diagnosed.Rolling bearing are common components in gear box. Their running state would influence the performance of the whole machine directly. In this paper, on the base of analyzing the vibration mechanism of rolling bearing, the types of typical faults were summarized. The methods of vibration signal analysis and fault diagnosis for gear box are introduced in detail. Besides easy diagnosis for the gear box, the method of precise diagnosis is put forward.Based on the fractal theory, the computing method of binary fractal of gridding dimension was put forward and dimension computing program was worked out. Fine results of dimension computation of pure sinusoidal and cosine signal were obtained. Fractal filtering using short-time fractal dimension as the parametric function was put forward, by which Weirestrass function was with fractal filtered. The result shows that fractal filtering is good in both reducing noise and maintaining time-domain signal.Based on gridding dimension of vibration signal of various sampling rate, a new fractal diagnostic method using dimension distance for the identification of the system condition is established, and got fine identifiable results. In this paper, a JZQ250 gear box is taken as the research object, the laboratorial equipments and models of signal collection are introduced, and the disposal and election of the observational points are depicted simply. The fractal diagnosis of rolling bearings has a correct result in time-domain.Fractal diagnosis requests little the outsider conditions, can immediately attain the result in time-domain the diagnosis and has a good versatility in the accurate judgement of systematic state.