Mechanics and dynamics of thin-wall milling process

Thin-walled workpieces, which are usually machined by milling process, are the typical structures used in automobile, aerospace and astronautic industries. Static deflection and dynamic chatter, which are harmful to the efficiency and effectiveness of the process, often occur in the milling of these structures. This chapter presents the understandings of the mechanics and dynamics in the thin-wall milling process. First, an analytical surface error model is established to consider the partial separation of the tool and the thin-walled workpiece due to static deflections and the interaction at the changing contact zones along the feed direction. Then, a dynamic governing equation together with the effect of the varying workpiece dynamics on the stability lobe diagrams (SLDs) in the thin-wall milling is developed. Finally, three hardware¬based methods for suppressing chatter are described. The first design is a passive damper, i.e., a dynamic vibration absorber (DVA), to suppress the chatter in the thin-wall milling by considering the in-process workpiece's dynamics induced by material removal. The second method uses a DVA to control the vibrations in the milling-trimming process of the plate-like workpieces designed for functional requirements such as invisibility. The third method suppresses the chatter in the thin-wall milling through a moving fixture to instantaneously and continuously provide additional stiffness and damping to the instantaneous contact position between the cutter and the workpiece, and as the device moves, the chatter can be suppressed without the need of any other hardware. A series of machining experiments show that the proposed methods are effective for detecting the mechanics and dynamics of the thin-wall milling process.