Prediction of Dynamic Stability Limit of Time-Variable Parameters System in Thin-Walled Workpiece High-Speed Milling Processes

A method for predicting dynamic stability limit of thin-walled workpiece high-speed milling process is described. The proposed approach takes into account the variations of dynamic characteristics of workpiece with the tool position (or machining time). A dedicated thin-walled workpiece representative of a typical industrial application is designed and modeled by finite element method. The curvilinear equation of modal characteristics changing with tool position is regressed. A specific dynamic stability lobe diagram is then elaborated by scanning the dynamic properties of workpiece along the machined direction throughout the machining process. The results show that, during thin-walled workpiece milling process, material removing plays an important part on the change of dynamic characteristics of system, and the stability limit curves are dynamic curves with time-variable. In practical machining, some suggestion is interpreted in order to avoid the vibrations. Then investigations are compared and verified by high speed milling experiments with thin-walled workpiece.