As a key rotating support component, planetary gearbox are the core of high-end equipment power transmission and load bearing. Planetary gearboxes usually operate in a complex state and are prone to failures, and the vibration signals measured in the early stages of failure show the characteristics of small amplitude, low energy, and strong noise. In order to improve the accuracy of equipment state diagnosis, it is necessary to analyze its vibration mechanism. Firstly, the vibration signal excitation model of planetary gearbox under normal working conditions is constructed. The amplitude modulation effect of transmission path on the vibration signal of gearbox, the phase difference between planetary gear and ring gear, and the phase difference between planetary gear and sun gear are considered in the model. In addition, the vibration mechanism of the inner and outer rings of the planetary gear bearing in fault state is analyzed, and the fault impact response model is established. By studying the response mechanism of vibration signal, this paper reveals the changes of the parameters and vibration signal model of mechanical equipment before and after the failure. It provides a model basis for fault diagnosis based on vibration signal processing.
 

vibration mechanism; signal response model; transmission path; phase difference; fault impact.