圧電素子を用いた長方形空気スクイーズ軸受に関する研究（リニアガイドへの応用）
Rectangular Squeeze-Film Gas Bearing Using a Piezoelectric Actuator
-- Application to a Linear Motion Guide --
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Aerostatic bearings have been applied to various precision devices due to the excellent accuracy of their motion. However, the supply of pressurized air to aerostatic bearings from an external source sometimes causes difficulties. For instance, it is difficult to supply pressurized air to aerostatic bearings inside a tightly sealed container or in any apparatus that does not have enough space for tubing.



Fig.4-1 Rectangular squeeze-film gas bearing



Fig.4-2 The proposed bearing-guideway system for a linear motion guide


In order to support an object by means of an air film without using pressurized air, squeeze-film bearings may be very useful. Various reports treating squeeze-film bearings exist. However, all of them describe a system in which an object is placed on a vibrating surface, and it would be difficult to apply this system to linear guides because long and narrow guideway surfaces must be vibrated. Therefore, to solve this problem, the author proposed a system wherein a source of vibration is built into the guiding surface. As seen in Fig.4-1, the structure of the proposed guide consists of a slider, a piezoelectric element attached to the slider and a counterweight connected through piezoelectric elements. When an alternating voltage is applied to the piezoelectric elements, the slider begins to oscillate due to the effect of the counterweight. As a result, a layer of air is formed under the slider from the effect of squeezing.
In this paper, we treat a squeeze bearing incorporating a rectangular slider, which is suitable for linear guides, and show the float characteristics of this bearing. Furthermore, we propose a guideway system using the proposed squeeze bearing and confirm the usefulness of the proposed bearing.



Fig.4-3 Experimental results for the average film thickness



Fig.4-4 Another type of gas squeeze bearing using elastic hinges

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