高转速效应下空气静压主轴微铣削加工表面形貌预测研究

Aerostatic spindle is the core component of ultra-precision machine tool, and its dynamic characteristics directly affect the machining performance of machine tool. Under high-speed conditions, the centrifugal force and gyroscopic torque of the rotor, and the dynamic parameters (stiffness and damping) of the air bearings vary with the speed, which in turn affects the dynamic characteristics of the aerostatic spindle. Due to the coupling effect between the dynamic characteristics of the spindle and the micro-milling process, the cutting force will fluctuate and change discontinuously under different cutting conditions. As a result, it often leads to a large vibration response of the spindle. If the vibration response is too large, it will cause the chatter phenomenon, which directly leading to workpiece surface processing failure. Therefore, based on Timoshenko beam element, an aerostatic spindle dynamic model considering speed effect and a 3D surface topography prediction model for micro-milling are established. And the influence of rotational speed and feed per tooth on the surface topography of the workpiece is quantitatively analyzed. The results show that during the steady cutting process, the distance between adjacent cutting marks on the workpiece surface increases gradually with the increase of the feed per tooth, causing the surface roughness increases linearly. When rotational speed and feed per tooth reach a small amount, the rotational speed can affect the machining efficiency, but has little effect on the roughness of the machined surface.