Abstract:  Aiming at the regenerative chatter problem which restricted the machining efficiency in the milling of thinwalled parts, an adjustable workpiece holder for machining thin-walled parts was proposed based on series mode coupling. Firstly, the adjustable workpiece fixture model was designed based on the principle of series mode coupling, and two new optimal tuning strategies (amplitude tuning and negative real part tuning) were proposed to improve the dynamic stiffness and milling stability of the fixture. Secondly, self-adaptive mechanisms such as rotating spring and eddy current module were used to realize the coupling between fixture mode and part mode, and conductive plate was introduced for damping adjustment. The feasibility and effectiveness of the workpiece fixture were verified by the part milling test with clear mode. The results indicate that the fixture is feasible and effective,the cutting surface roughness decreases from Ra 2.4μm to Ra 0.9μm when the cutting depth is 3mm. Compared with the conventional holder, the dynamic stiffness and milling stability of the proposed holder is significantly improved.

Key words:  thin-walled parts; workpiece holder; modal coupling; damping; regenerative chatter