JPH06115916A - Gas bearing - Google Patents

Abstract

PURPOSE:To prevent the damage of a surface facing the gap for forming a gas film by using a hard material as the material for the surface facing the gap for forming a gas film and using a graphite material as the material for the other surface and making the surface to have a specific surface roughness. CONSTITUTION:The outer circumference 13 of an inner material 11 of a gas bearing 10 is formed in the form of a spool having radius continuously increasing from the center to the end part in axial direction. The surface is finished to mirror face having a surface roughness of <=0.2s with a hard material such as hard chromium plating. An end of the inner material 11 is protruded sideways to form a supporting part 14 to fix and support the bearing. An introduction port 15 for a compressed gas is opened at an end of the supporting part 14, and a central path 16 having channels 17 radially extending from the inlet port 15 is provided. The inner circumference 19 of the outer material 12 positioned outside of the inner material 11 is made of a graphite material and finished to a surface roughness of 0.8-1.5s. A gap 20 for forming a gas film having uniform thickness is formed between the outer circumference 13 of the inner material 11 and the inner circumference 19 of the outer material 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas bearing which is used by supplying a pressurized gas and forming a gas film in a gap between two members rotating with each other.

[0002]

2. Description of the Related Art A gas bearing is provided with a gas film between members that rotate with each other, and has little friction, so that it is mainly used for ultra-high speed rotation. In this bearing, when a load larger than the allowable load is applied during rotation, both members come into contact with each other, causing seizure in a short time, and easily damaged.
Further, even when stationary, if a load is applied without supplying the pressurized gas, the surface of the member is likely to be damaged and the performance may be impaired.

For this reason, conventionally, the surface facing the gas film forming gap has been finished to a hard and smooth surface by hard chrome plating, alumite treatment, nickel plating, etc., but the above inconvenience is sufficiently solved. It hasn't arrived yet.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to eliminate the above-mentioned inconvenience, to make the surface facing the gas film forming gap less likely to be damaged, and to obtain a bearing with more stable performance. .

[0005]

According to the present invention, the surface of one member facing the gas film forming gap is formed with a hard material such as hard chrome plating to have a surface roughness of 0.2 S or less. The surface roughness of the member surface of No. 1 is 0.8-1.
It is a gas bearing characterized by being formed in 5S.

Further, as a particularly preferred embodiment of the present invention, the above structure is applied to a gas bearing in which the gas film forming gap is formed in a substantially pincushion shape in which the radius increases in a curve as the radius advances from the center in the axial direction to the end. Included gas bearings.

The smoother the surface of the hard material is, the better. It is more preferable that the surface of the hard material has a mirror finish of 0.1S or less. It is preferable that the surface of the graphite material has some degree of unevenness within the range that does not disturb the flow of gas through the gap, because it reduces friction, and it is difficult to process it to a highly smooth surface. It is preferable to have the unevenness of about 1 micrometer obtained in step 1.

[0008]

In the present invention, when both members come into contact with each other, the smooth hard material comes into contact with the graphite material having lubricity, so that the friction is extremely small and the melting point of the graphite material is extremely high. It is unlikely to occur.

When applied to a bearing having a structure in which the gap has a substantially pincushion shape, the radius of the gas film forming gap increases in a curved shape as the gas advances from the central portion to both ends, and the gas film forming gap increases. Since the cross-sectional area of the gas also increases smoothly, the gas flow becomes smooth and a strong gas film is formed. Therefore, even if a graphite material having irregularities on the surface is used, the permissible load is not reduced due to the turbulence of the gas flow. Furthermore, since there are no corners in the gap, the load is not concentrated even when both members are in contact with each other, and damage is less likely to occur even if a graphite material having a relatively low strength is used.

[0010]

The present invention will now be described with reference to the illustrated embodiments.
This will be specifically described.

The gas bearing 10 comprises an inner member 11 and an outer member 12.

The inner member 11 is made of brass (copper alloy), aluminum, stainless steel or the like, and the outer peripheral surface 13 is formed in a substantially pincushion shape in which the radius increases in a curved shape as it goes from the center in the axial direction to the end. The surface is plated with hard chrome and finished to a mirror surface with a surface roughness of 0.1S. One end of the inner member 11 has a support portion 14 protruding laterally.
Next, it is fixed and supported here. An inlet port 15 for receiving pressurized gas is provided at the tip of the support portion 14,
A central passage 16 extends from the introduction port 15 to the central portion, and several radial passages 17 extend radially from the central passage 16 and are connected to an ejection port 18 at the axial center of the outer peripheral surface 13.

The outer member 12 is formed by cutting a graphite material, is located on the outer periphery of the inner member 11, and the inner peripheral surface 19 thereof has a shape along the outer peripheral surface 13 of the inner member, and the outer peripheral surface 13 is formed. A gas film forming gap 20 having a uniform thickness of several to several tens of micrometers is formed between the and. This inner surface 19
Has a surface roughness of 0.8 to 1.5S.

The inner member 11 is actually formed so that it can be separated into the right and left at the radiation passage 17 portion, and the outer member 12 can be attached integrally.

The bearing 10 has the above-mentioned structure, and the support portion 14 is fixed, pressurized gas is supplied to the inlet port 15 and ejected from the ejection port 18 to form a gas film in the gas film formation gap 20. Then, the outer member 12 is rotated and used.

In this example, the entire outer member 12 is made of a graphite material, but it is also possible to form only the inner peripheral surface 19 part by the graphite material and the other parts by another material. Needless to say. In contrast to this example, it is also possible to employ a structure in which the outer peripheral surface of the inner member is a graphite material and the inner peripheral surface of the outer member is a hard material.

[0017]

As described above, in the gas bearing of the present invention, the surfaces of both members forming the gas film forming gap are made of a smooth hard material and a graphite material having appropriate irregularities.
Even if they come into contact with each other due to overload during rotation, seizure is unlikely to occur and damage is less likely to occur. In addition, even when the load acts while the pressurized gas is not supplied while stationary,
It is extremely convenient to handle as it is less likely to be damaged.

Further, when applied to a bearing having a structure in which the gap has a substantially wound shape, the gas film is strong,
Since the allowable load is not reduced and the gap has no corners, the load is not concentrated even when both members are in contact with each other, damage is unlikely to occur, and stable performance is secured.

[Brief description of drawings]

FIG. 1 is a front sectional view of an embodiment of the present invention.

[Explanation of symbols]

10 ... Gas bearing, 11 ... Inner member, 12 ... Outer member, 13 ...
Outer peripheral surface, 19 ... Inner peripheral surface, 20 ... Gas film forming gap.

Claims (2)

[Claims] 1. The surface of one member facing the gas film forming gap is formed to have a surface roughness of 0.2 S or less by using a hard material such as hard chrome plating, and the other member surface is formed of a graphite material. A gas bearing characterized by being used to form a surface roughness of 0.8 to 1.5S. 2. A gas bearing in which the structure of claim 1 is applied in a gas bearing formed in a substantially pincushion shape in which the gas film forming gap increases in a curved shape as the radius advances from the center in the axial direction to the end.