The Analysis Of The Failure Mechanism Of The Gears Based On Time-frequency Theory

As a power transmission components, the gear and gear box play an indispens-able role in large rotating machinery and the damage caused by their fault would be very serious.At present, the gear failure research at home and abroad mainly focus on the specific methods of failure analysis, and the failure mechanism is less researched. In this paper, the failure mechanism of tooth broken and unparallel gear shaft of the helical gear were studied. For the limitation of traditional signal analysis which based on the Fourier transform, time-frequency analysis was used to study the characteristic of the gear failure in this paper. The main content and conclusions are as follows:First of all, various types of gear failure modalities and the vibration mechanism of gear system were analyzed. The model of tooth broken failure of the helical gear was established based on the research of calculation of the gear stiffness. From the aspect of dynamics,teeth broken failure mechanism of helical gear was studied.The dimensionless equations of the vibration system was built and the characteristics of the simulation signal of the gear tooth broken was studied by using time-frequency analysis method. The research shows that after the event of the gear tooth broken, a bias quality is generated by the broken gear. Due to the impact of the broken tooth, there would be a stiffness mutations at the place of broken tooth, and a fierce surge characteristic would be show up. The impact frequency equals to the frequency of the axis.In this paper, based on the model of unparallel gear shaft gear system, and the failure mechanism of unparallel gear shaft was studied. The research shows that the vibration of the gear shaft increased with the axle offset which is not parallel. The second harmonic frequency of the failure rotating shaft is the typical frequency of the system.Finally, using the time frequency analysis method to diagnosis the field fault of gear system and the conclusions of this study were verified in this paper.