Research on the dynamic characteristics of the ultra-precision fly cutting machine tool and its influence on the mid-frequency waviness of the surface

With the increasing demand for machining accuracy of machine tools, the dynamic characteristics of ultra-precision fly cutting machine tool (UFCMT) have increasingly prominent impacts on the machining accuracy. Based on the transfer matrix method for multibody systems (MSTMM), the dynamics model and its topology figure are established, and the dynamic response of the UFCMT is computed. The modal test of the UFCMT and the vibration test of the tool tip are carried out, which verifies the correctness of the dynamics model. To research causes of the formation of the mid-frequency waviness on the machined surface, the machined surfaces at different rotating speeds are measured. By extracting the characteristic frequencies of mid-frequency waviness of the machined surface and comparing with the results from the modal test and the vibration test, the dynamic characteristics of the spindle and the tool holder are main factors that form the mid-frequency waviness. By optimizing the connect stiffness between the tool holder and the fly cutting head, the displacement of the tool tip and the peak to valley (PV) value of the machined surface in the range of mid-frequency waviness is decreased.