| Swing mechanism is a great important part of the hydraulic excavator. It is worth mentioning that the rotary work accounts for the whole working cycle of65%～75%, therefore, it is that its dynamic properties impacts great on hydraulic excavator performance. It is one of the important signs of its design level. However, its vibration mechanism is not fully understood still. It reduces its reliability severely and hinders its development deeply. As a result, it is great important theoretical significance for the whole design to study vibration dynamic characteristics about it. Because of this, the purpose of this study is to solve the deep-seated problems about its nonlinear dynamic characteristic. Based on it, the main content of this paper is as follows:According to the vibration mechanics theory, elastic dynamics theory and lubricating fluid theory, the dynamic model of the swing mechanism is established by the finite element methods (FEM). Firstly, the kinematics relationship are given. Then, the Slewing Support Mechanism dynamics model is established. Secondly, the rotary drive mechanism dynamics model is established by FEM. Finally, based on their models, considering the coupling between the two relations, the coupling dynamic equations of the system are established by FEM. The dynamic equations discover the actual relation between macroscopic dynamic characteristics, the structure parameters and load parameters.Dynamics equation about it is solved by a mode-superposition method, at the same time, using the method of multiple scales, its dynamic performance is studied deeply. Firstly, the expression of self-excited inertia force is given. Then, its dynamic characteristics are analyzed deeply by the method of multiple scales. Secondly, study the relationship between work device and slewing mechanism, meanwhile, analyzing the impact of rotary inertia of the work device on the slewing mechanism. Finally, the dynamic characteristics are analyzed under interactions between the extrinsic and intrinsic prompting. In consequence, it turned out that there are the combination resonance and the multiple resonance phenomenon. Above all, its vibration mechanism is revealed deeply.Through the dynamic simulation calculation of example, it shows that it is in the presence of multiple resonance phenomenon, and also proves that it and working unit moment of inertia are closely related. Furthermore, it provides a theoretical basis for further study of vibration problems on the slewing mechanism. Finally, it made the experiment. The results show that the mathematical model in this paper and the related research is valid. |
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