高速空気静圧スピンドルの熱的特性の基礎解析

抄録

In recent years, ultra-precision cuttings using micro-milling cutter to produce parts with micro structural surfaces are being demanded. The parts with the micro structural surfaces are used for various fields based on state-of-the-art technology, such as automobile, optical industries and so on. An importance of ultra-precision machine tools for machining dies used for the molding processes of the precise components increases more than before. In the machining of the micro structural surfaces using micro milling cutter, high-speed and precise rotational motion of the machine tool spindle are indispensable to conducting the machining successfully. During machining processes, the spindle temperature increases due to the heat generation of the spindle and machining processes. Resultant thermal deformation of the spindle degrades machining accuracy. Accordingly, the temperature change must be suppressed.

In this study, an ultra-high speed aerostatic spindle of a rated rotational speed of 100,000 min-1, with better thermal stability is considered. To design thermally stable spindle, cooling structures are specifically designed in the spindle casing and shaft bore inside rotating shaft. It should be mentioned that the shaft diameter of the high speed spindle is necessarily small. A specially designed structure for the shaft bore water cooling is thus considered for the spindle with the aero-static bearings. The thermal characteristics of the designed spindle are investigated using simulation studies. The simulations are carried out using the introduced lumped parameter model and the finite-element model.