浮動ブシュ静圧気体ジャーナル軸受に関する研究（スロット絞りを用いた場合）
AFloating Bush Journal Aerostatic Bearings Employing Slot Restrictors
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The demand of a high speed internal grinder is increasing in effectively manufacturing miniature bearings. This kind of spindle requires relatively high stiffness and an excellent stability at high speed region. It is well known that aerostatic bearings are very suitable for a high speed spindle because of their low friction. But even in aerostatic bearings, there are difficulties in achieving both DN value of more than 3.5 million and bearing stiffness high enough for an internal grinder used in manufacturing miniature bearings.



Fig.3-1(a) The proposed floating-bush aerostatic journal bearing



Fig.3-1(b) Gas flow pattern


In this paper, a new type of floating bush aerostatic journal bearing is proposed to satisfy the above conditions. The proposed bearing employs slot restrictor and is operated in a relatively small bearing clearance to obtain high stiffness. Furthermore, in order to get an excellent stability, the proposed bearing has a floating bush supported by an aerostatic bearing as shown in Fig.3-1. The floating bush can also rotate with a rotor and reduces the power consumption of a bearing in a high speed region. In this paper, the stability of a rigid rotor supported by the proposed bearings is rotated theoretically and experimentally



Fig.3-2 Two kinds of floating bushes are prepared. The outer bearing clearance;15 micro meter 20 micro meter



Fig.3-3 Relationship between inner bearing clearance and threshold speed of instability




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