Dynamic Analysis And The Fault Diagnosis Of Vibrating Screen

Vibration is unnecessary and harmful for mechanical equipment and mechanical structure in many cases, which often causes malignant destruction and failure of them as the direct factor. However, vibration can be made use of in vibrating screen. The screen is widely used in industry fields, carrying out material separation and dehydration, etc. Because of bad working condition, long working time and heavy working intensity, vibrating screen is easily put into malfunction, affecting the whole production line and causing great economic losses. The theory of fault diagnosis of vibrating screen is not mature yet, so the related research has the significance and practical value.This thesis mainly aims at fault signal that is difficult to extract in fault diagnosis of vibrating screen due to its large impact and vibration. Among faults in vibrating screen operation, this thesis takes rolling bearing's fault as an example, extracting fault signal and completing fault recognition. Vibration signal is analyzed when bearing is normal and at fault respectively using MATLAB and ORIGIN, by observing the signal characteristics. The method of envelope analysis is mainly used to process signal, thereby extracting fault signal, obtaining the fault features and identifying the fault. Through the envelope analysis and processing on the actual signal, the problem of extracting fault signal of vibrating screen is solved and good results are achieved.Based on the analysis on spectrum characteristic of rolling bearing of rotating machinery, the characteristic of vibrating screen's structure is studied in this thesis, thus the spectrum characteristic of the bearing's fault is obtained. The spectrum characteristic found is different from that of rotation machinery. There is modulation in the outer spectrum, while there is no modulation in inner circle, which are contrary to rotating machine. The new discovery provides a theoretical support and basis for the bearing fault diagnosis of vibrating screen.Because the service life of vibrating screen is related to the motion characteristic, abnormal vibration is easy to damage the structure, which affect the service life.The motion characteristics of vibrating screen is also analyzed and studied in this thesis. The model of vibrating screen is builded using ANSYS, then modal analysis and harmonic response analysis are done for the model. Characteristic of vibration mode and frequency of each order are obtained. And the vibrational state and stress concentration area are shown for the structure of vibrating screen under the influence of eccentric force with various frequency, so structural damage is provided auxiliary help by the result of the dynamic analysis.