Chatter analysis and mitigation of milling of the pocket-shaped thin-walled workpieces with viscous fluid

This article presents a theoretical method to analyze the dynamic behavior of the milling process of the pocket-shaped thin-walled workpieces, which are filled with viscous fluid to suppress the chatter vibrations. Dynamic models of both the spindle-tool system and the pocket-shaped thin-walled workpiece with the viscous fluid are derived by extending the principles of the fluid-structure interaction dynamics theory and structural mechanics. The in-process dynamical parameters of the tool and the workpiece, i.e. natural frequency and modal shape, are solved by comprehensively integrating the effects of the viscous fluid, material removals, and tool position changes. Based on the built models, a method for analyzing the machining stability of this kind of workpieces after using the viscous fluid in the milling process is carried out and the avoidance principle of chatter vibrations is established by reasonably selecting the cutting parameters. A series of simulation and experimental tests are conducted on a typical pocket-shaped thin-walled workpiece to verify the reliability and effectiveness of the proposed methods for the suppression of chatter during the whole milling process.