熱的安定性向上を目的とした軸心水冷機構を有する高速空気静圧ビルトインスピンドルの基本設計

抄録

Ultra-precision machining that is carried out using ultra-precision machine tool is essential for producing precise parts that are used in the industries such as medical, automobile and optical industries. In general, the ultra-precision machine tools are equipped with the spindle supported with aerostatic bearings. In particular, demands for the parts with micro-structures are currently increasing. The micro-structural geometries are in many cases machined using micro-milling tools with extremely high spindle speeds. This paper deals with a design study on high-speed spindle supported by aerostatic bearings and driven by a built-in motor. The rated rotational speed of the spindle aims at 100,000 min-1. In such high-speed operation of the spindle, heat generation must be significantly remarkable. In this paper, the temperature changes of the spindle are investigated via simulations that are carried out using an introduced lumped parameter model. The model considers the power losses due to the influences of the viscous torque of air, air pressure losses and the built-in motor. Effects of shaft-bore water cooling structure on the thermal stability are also discussed. Temperature change of the spindle body and shaft are investigated. Furthermore, the effectiveness of the water cooling and suitable cooling conditions are studied in the simulation studies.