Robotic machining systems have been widely implemented in the assembly sites of large components of aircraft, such as wings, aircraft engine rooms, and wing boxes. Milling is the first step in aircraft assembly. It is considered one of the most significant processes because the quality of the subsequent drilling, broaching, and riveting steps depend strongly on the milling accuracy. However, the chatter phenomenon may occur during the milling process because of the low rigidity of the components of the robotic milling system (i.e., robots, shape-preserving holders, and rod parts). This may result in milling failure or even fracture of the robotic milling system. This paper presents a feasible spindle speed interval identification method for large aeronautical component milling systems to eliminate the chatter phenomenon. It is based on the chatter stability model and the analysis results of natural frequency and harmonic response. Firstly, the natural frequencies and harmonics of the main components of the robot milling system are analyzed, and the spindle speed that the milling system needs to avoid is obtained. Then, a flutter stability model considering the instantaneous cutting thickness is established, from which the critical cutting depth corresponding to the spindle speed can be obtained. Finally, the spindle speed interval of the robotic milling system could be optimized based on the results obtained from the chatter stability model and the analysis result of the natural frequency and harmonic response of the milling system. The effectiveness of the proposed spindle speed interval identification method is validated through time-domain simulation and experimental results of the large aeronautical component milling system.

中文翻译：

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大型航空零部件机器人铣削系统可行主轴转速区间辨识方法

机器人加工系统已广泛应用于飞机大型部件的装配现场，如机翼、飞机发动机舱、翼盒等。铣削是飞机组装的第一步。它被认为是最重要的工艺之一，因为后续钻孔、拉削和铆接步骤的质量在很大程度上取决于铣削精度。然而，由于机器人铣削系统的部件（即机器人、保形支架和杆件）的刚性较低，在铣削过程中可能会出现颤振现象。这可能会导致铣削故障甚至机器人铣削系统断裂。本文提出了一种可行的大型航空部件铣削系统主轴转速区间辨识方法，以消除颤振现象。它基于颤振稳定性模型以及固有频率和谐波响应的分析结果。首先对机器人铣削系统主要部件的固有频率和谐波进行分析，得到铣削系统需要避免的主轴转速。然后，建立考虑瞬时切削厚度的颤振稳定性模型，由此可以得到与主轴转速对应的临界切削深度。最后，根据颤振稳定性模型的结果以及铣削系统固有频率和谐波响应的分析结果，可以优化机器人铣削系统的主轴转速区间。通过大型航空部件铣削系统的时域仿真和实验结果验证了所提主轴转速区间辨识方法的有效性。