スクイーズ空気膜による非接触位置決め特性の基礎的研究

ステップ応答の数値的解析と実験的検証

抄録

The aim of this study is to consider positioning characteristics of floating object suspended by steady-state squeeze air films. For the columned thrust squeeze air bearing model, the numerical analysis technique based on Lees' difference approximation method is applied to solve the Reynolds equations. The piezo-driven oscillating pad generates the steady-state squeeze air film and step motion for shifting the floating object. The numerical results for the step response of the object position and air film pressure extremely agreed with the experimental ones. The step response showed the strong nonlinearity of dynamic air film characteristics. The phase lag between squeeze motion and step feed motion has a great influence on the step response. Because the squeeze motion is sinusoidal oscillation, the acceleration which acts on floating object affects with phase lag. Therefore minimizing the acceleration by controlling the phase lag can decrease the overshoot. The numerical results are shown in case of single air film generation on lower side and in case of dual air films on upper and lower sides. As a result, the operation with dual air films increases the damping characteristic and is effective to decrease the overshoot especially for the large step width.