Dynamic model and stability prediction of thin-walled component milling with multi-modes coupling effect

摘要

Dynamic characteristics of thin-walled parts milling system have position-dependent and aggregation modes, which means that multi-modes are close with each other. They (generally the first few vibration modes) may be simultaneously excited by cutting forces in milling process. Therefore, multi-modal couple effect plays a significant impact on thin-walled parts milling process in some cases. The existing Single Mode Theory (SMT) cannot accurately predict milling stability. Additionally, it is very difficult for traditional experimental modal analysis method (e.g., hammer test) to extract the dynamic characteristics of structures in order to handle the coupling modes. To overcome these problems, Multi-Modes Theory (MMT) is updated and investigated thoroughly, and a comprehensive method, Modal Coupled Method (MCM) is proposed to consider these effects in the paper, where the thin plate theory and penalty parameter method are employed and integrated to model the system structure and boundary conditions. Then the comparisons with MCM and existing multi-modes method Lowest Envelope Method (LEM) and SMT are presented and discussed to confirm the efficiency and accuracy of this method applied to stability prediction of thin-walled parts milling. Finally, two case studies are performed to verify the consistency between the numerical and experimental results, it's show that for the system with timevarying dynamic characteristics, e.g., thin-walled part milling process, MCM is the better choice for stability prediction when the modal coupling characteristics are unknown, because to determine whether the modes are coupled or not at different cutting positions ahead of time is very difficult.