Dynamic Characteristics Of The Air Static Pressure Spindle System Of Diamond Flying Cutter

As the key equipment maching large-aperture ultra-precise flat optics, Diamond fly cutting (DFC) has achieved widespread use in manufacturing national defense and civil sophisticated products, such as precise guidance, night vision, thermal imaging and high-power laser weapons.Aerostatic bearing spindle (ABS) is the core component to realize rotary motion for DFC machine tool. For practical use, the aerostatic bearing spindle system is influenced by forces resulting from cutting force, drive system and various environmental disturbances. These forces result in relative movement between the tool and workpiece, leading to the change of the expected position between them. Consequently, waveness error is present on the machined surface and the surface quality is degraded. Hence, to enhance the resistance to vibration and stability of DFC machine, it is necessary to study the dynamic characteristics of ABS system and detect the sensitive point to vibration. Following researches have been done in this paper:(1) The dynamic characteristic model of ABS is established. Based on the lumped mass model, the kinetic equation is obtained, which is the foundation for studying the dynamic characteristics of ABS.(2) Based on the dynamics characteristic theory of joint interface, the dynamic characteristics of typical ABS joint interface is analyzed theoretically and experimentally. The dynamic characteristics parameters of joint interface between the gas film and bolts and its variation are obtained.(3) The dynamic characteristics model of ABS is established from combination of numerical simulations and modal experiments. The dynamic characteristic parameters of ABS and its variation are determined.(4) From the practical machining with DFC machine tool, the correspondence between dynamic characteristics of ABS and waveness error of machined surface is established with feature frequency identification method. The sensitive point of ABS to vibration is found and is optimized to increase its resistance to vibration. The effective of optimization is verified by DFC experiments.The integrating joint interface dynamic model of ABS of DFC machine is established finally, and the ABS parameters are optimized. The optimization of ABS reduces the RMS of PSD1 error (space period ranging from 2.5mm to 33mm) of machine surface from 53nm to 12nm.