JP2023149956A - Static pressure air bearing device - Google Patents

Abstract

To provide a static pressure air bearing device which can suppress a deformation of a porous plate material.SOLUTION: A static pressure air bearing device comprises a porous plate material and a base material. The porous plate material has a bearing face and a first mating face being a face at a side opposite to the bearing face. The base material has a second mating face which abuts on the first mating face. An air supply cavity which is formed by recessing either of, or both the first mating face and the second mating face is provided between the porous plate material and the base material. An air supply cavity which is formed by recessing either of or both the first mating face and the second mating face is provided between the first mating face and the second mating face. The porous plate material and the base material are formed into square shapes when viewed from a first direction parallel with a perpendicular line with respect to the bearing face. An air supply port penetrating in the first direction, and communicating with the air supply cavity is provided at the base material. The air supply cavity is formed into an annular shape when viewed from the first direction. The porous plate material and the base material are fastened to each other by a fastener at four corner parts.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a hydrostatic air bearing device.

A static air bearing device is a device that generates a thin film of gas between a bearing surface and an object to be supported. An example of this static pressure air bearing device is one that utilizes a porous plate material (hereinafter referred to as a porous plate material). In the following patent document, a metal sintered body having a high Young's modulus is used as a porous plate material.

Japanese Patent Application Publication No. 2000-27865

In addition to the porous plate material, the hydrostatic air bearing device includes a base material that supports the porous plate material, and the porous plate material is stacked on the base material. Moreover, an air supply cavity is provided between the porous plate material and the base material. The air supply cavity in the above-mentioned patent document is located in the center of the porous plate material and has a circular shape when viewed from above. This air supply cavity has a large capacity and a large pressure acts on the porous plate material. Therefore, when the hydrostatic air bearing device was driven, the central portion of the porous plate material was deformed so as to protrude toward the bearing surface side.

The present disclosure has been made in view of the above, and an object of the present disclosure is to provide a hydrostatic air bearing device that can suppress deformation of a porous plate material.

In order to achieve the above object, a hydrostatic air bearing device according to one aspect of the present disclosure includes a porous plate material and a base material stacked on the porous plate material. The porous plate material has a bearing surface and a first mating surface opposite to the bearing surface. The base material has a second mating surface that abuts the first mating surface. An air supply cavity formed by recessing one or both of the first mating surface and the second mating surface is provided between the porous plate material and the base material. An air supply cavity formed by recessing one or both of the first mating surface and the second mating surface is provided between the first mating surface and the second mating surface. The porous plate material and the base material have a rectangular shape when viewed from a first direction parallel to a perpendicular line to the bearing surface. The base material is provided with an air supply port that penetrates in the first direction and communicates with the air supply cavity. The air supply cavity has an annular shape when viewed from the first direction. The porous plate material and the base material are fastened at four corners by fasteners.

The air supply cavity is annular. That is, in the porous plate material, the pressure of the compressed gas does not act on the portion facing the central portion of the air supply cavity (annular). Therefore, the pressure acting on the porous plate material is kept low. Moreover, the four corners of the porous plate material are fastened with fasteners. Therefore, the fixing strength for fixing the porous plate material is high. Therefore, the porous plate material is difficult to deform toward the bearing surface.

Further, in the hydrostatic air bearing device of the present disclosure, each corner of the bearing surface includes a stepped surface recessed toward the first mating surface, a recessed accommodation hole provided in the stepped surface, and a recessed accommodation hole provided in the stepped surface. It has a through hole that penetrates a portion of the bottom surface of the hole and the first mating surface. Each corner of the second mating surface is provided with a female screw hole that overlaps with the through hole when viewed from the loading direction. The shaft portion of the fastener passes through the through hole and is screwed into the female threaded hole. The head of the fastener may be disposed in the receiving hole and tightened on the bottom surface of the receiving hole toward the base material.

Moreover, the step surface of the hydrostatic air bearing device of the present disclosure may have a rectangular shape when viewed from the loading direction.

Moreover, the step surface of the hydrostatic air bearing device of the present disclosure may have a triangular shape when viewed from the loading direction.

According to the hydrostatic air bearing device of the present disclosure, deformation of the porous plate material can be suppressed.

FIG. 1 is a cross-sectional view of a hydrostatic air bearing device according to a first embodiment, and more specifically, a cross-sectional view taken along the line II in FIG. 2. FIG. FIG. 2 is a plan view of the hydrostatic air bearing device according to the first embodiment, viewed from a first direction. FIG. 3 is a cross-sectional view of the hydrostatic air bearing device according to the second embodiment, and more specifically, a cross-sectional view taken along the line IV--IV in FIG. FIG. 4 is a plan view of the hydrostatic air bearing device according to the second embodiment, viewed from the first direction. FIG. 5 is a sectional view of a hydrostatic air bearing device according to Embodiment 3, and more specifically, a sectional view taken along the line VI-VI in FIG. FIG. 6 is a plan view of the hydrostatic air bearing device according to the third embodiment, viewed from the first direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Modes for carrying out the invention will be described in detail with reference to the drawings. The present disclosure is not limited to the content described in the following description. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the components described below can be combined as appropriate.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a hydrostatic air bearing device according to a first embodiment, and more specifically, a cross-sectional view taken along the line II in FIG. 2. FIG. FIG. 2 is a plan view of the hydrostatic air bearing device according to the first embodiment, viewed from a first direction. As shown in FIG. 1, the hydrostatic air bearing device 100 includes a porous plate material 1, a base material 2, and four bolts (fasteners) 4.

In the following description, the direction in which the porous plate material 1 and the base material 2 overlap will be referred to as the lamination direction. Among the stacking directions, the direction in which the porous plate material 1 is arranged when viewed from the base material 2 is referred to as a first direction X1. A direction opposite to the first direction is referred to as a second direction X2.

The porous plate material 1 is a porous material (for example, graphite, ceramics, metal powder sintered body) formed into a plate shape and provided with many pores that serve as gas passages. The porous plate material 1 includes a porous main body 10, a bearing surface 11 facing the first direction X1, and a first mating surface 12 facing the second direction X2.

As shown in FIG. 2, the porous main body 10 has a square shape when viewed from the stacking direction. Therefore, one side 10a and the other side 10b of the porous main body 10 intersect at right angles. The bearing surface 11 is a surface facing the object to be supported, and is a flat surface. Each of the four corners of the bearing surface 11 is provided with a stepped surface 13 that is recessed in the second direction X2 relative to the bearing surface 11.

The stepped surface 13 has a rectangular shape when viewed from the first direction X1. Furthermore, a boundary surface 18 extending in the stacking direction is provided between the bearing surface 11 and the stepped surface 13. The boundary surface 18 is provided with a first boundary surface 18a extending parallel to one side 10a of the porous main body 10, and a second boundary surface 18b orthogonal to the first boundary surface 18a. Further, the corner where the first boundary surface 18a and the second boundary surface 18b intersect is chamfered to form an arc-shaped R portion 18c.

As shown in FIG. 1, a circular accommodation hole 14 is provided in the step surface 13. The bottom surface 15 of the accommodation hole 14 is provided with a through hole 16 that penetrates in the second direction X2. The first mating surface 12 is a flat surface. The first mating surface 12 is provided with a concave surface 17 that is depressed in the first direction X1. As shown in FIG. 2, the concave surface 17 is an annular groove. Further, the concave surface 17 has a circular shape centered on the central portion P of the porous main body portion 10.

As shown in FIG. 1, the base material 2 is a substrate that supports the porous plate material 1. The base material 2 has a base material main body portion 20, a second mating surface 21 facing in the first direction X1, and a bottom surface 22 facing in the second direction X2. The base material main body portion 20 has a square shape when viewed from the stacking direction, and has the same shape as the porous plate material 1. The second mating surface 21 is in contact with the first mating surface 12 of the porous plate material 1 . The second mating surface 21 covers the concave surface 17 from the second direction X2. Thereby, the internal space of the concave surface 17 becomes an annular air supply cavity 3.

Note that in this embodiment, the first mating surface 12 is provided with the concave surface 17 to form the annular air supply cavity 3, but in the present disclosure, the second mating surface 21 is provided with the concave surface 17 to form the air supply cavity 3. A cavity 3 may also be formed. Alternatively, the air supply cavity 3 may be formed by providing the concave surface 17 on both the first mating surface 12 and the second mating surface 21.

The base material main body portion 20 is provided with a circular air supply port 23 that penetrates in the stacking direction. The air supply port 23 overlaps the air supply cavity 3 when viewed from the stacking direction. Therefore, compressed air is supplied to the air supply cavity 3 through the air supply port 23 . A female screw hole 24 is provided at each of the four corners of the second mating surface 21 . This female screw hole 24 overlaps with the through hole 16 when viewed from the stacking direction.

The bolt 4 includes a shaft portion 40 having a threaded groove on its outer circumferential surface, and a head portion 41 provided at an end of the shaft portion 40 in the first direction X1. The shaft portion 40 of the bolt 4 is inserted into the through hole 16 and screwed into the female threaded hole 24 . The head 41 of the bolt 4 tightens the bottom surface 15 of the housing hole 14 in the second direction X2. Thereby, the porous plate material 1 and the base material 2 are integrated. The head 41 of the bolt 4 is accommodated in the accommodation hole 14 and does not protrude beyond the stepped surface 13 in the first direction X1.

As described above, according to the static air bearing device 100 of Embodiment 1, when compressed air is supplied from the air supply port 23 to the air supply cavity 3, the compressed air in the air supply cavity 3 passes through the porous plate material 1 and reaches the bearing. Compressed air is injected from the surface 11. Therefore, a thin film of gas is generated on the bearing surface 11.

Moreover, pressure in the first direction X1 is applied to the porous plate material 1 from the air supply cavity 3. Here, the air supply cavity 3 has an annular shape, and pressure in the first direction X1 does not act on the annularly surrounded central portion of the air supply cavity 3. Therefore, the pressure acting on the porous plate material 1 is kept small. Moreover, since it is tightened with four bolts (fasteners) 4, the porous plate material 1 is difficult to deform in the stacking direction. Therefore, when the hydrostatic air bearing device 100 is driven, the porous plate material 1 does not deform to protrude in the first direction X1. Therefore, the positional accuracy of the bearing surface 11 is improved. Further, since the porous plate material 1 is not deformed, the amount of ejection from the bearing surface 11 is equalized at each part of the bearing surface 11, and stable bearing performance can be exhibited.

As described above, the hydrostatic air bearing device 100 of Embodiment 1 includes the porous plate material 1 and the base material 2 stacked on the porous plate material 1. The porous plate material 1 has a bearing surface 11 and a first mating surface 12 that is an opposite surface to the bearing surface 11. The base material 2 has a second mating surface 21 that abuts the first mating surface 12 . An air supply cavity 3 is provided between the porous plate material 1 and the base material 2, which is formed by recessing one or both of the first mating surface 12 and the second mating surface 21. The porous plate material 1 and the base material 2 have a rectangular shape when viewed from the stacking direction in which the porous plate material 1 and the base material 2 are stacked. The base material 2 is provided with an air supply port 23 that penetrates in the loading direction and communicates with the air supply cavity 3. The air supply cavity 3 has an annular shape when viewed from the loading direction. The four corners of the porous plate material 1 and the base material 2 are fastened with fasteners (bolts 4).

According to this embodiment, it is possible to suppress the porous plate material 1 from deforming so as to protrude in the first direction X1.

In the hydrostatic air bearing device 100 of the first embodiment, each corner of the bearing surface 11 has a stepped surface 13 recessed toward the first mating surface 12 and a recessed accommodation hole 14 provided in the stepped surface 13. and a through hole 16 that passes through a part of the bottom surface 15 of the accommodation hole 14 and the first mating surface 12. Each corner of the second mating surface 21 is provided with a female threaded hole 24 that overlaps the through hole 16 when viewed from the loading direction. The shaft portion 40 of the fastener passes through the through hole 16 and is threaded into the female threaded hole 24 . The head 41 of the fastener is arranged in the receiving hole 14 and tightens the bottom surface 15 of the receiving hole 14 towards the base material 2 . Next, Embodiments 2 and 3, which are partially modified versions of the hydrostatic air bearing device 100 of Embodiment 1, will be described. Further, in the following description, the explanation will focus on the differences from the first embodiment.

(Embodiment 2)
FIG. 3 is a cross-sectional view of the hydrostatic air bearing device according to the second embodiment, and more specifically, a cross-sectional view taken along the line IV--IV in FIG. FIG. 4 is a plan view of the hydrostatic air bearing device according to the second embodiment, viewed from the first direction.

As shown in FIG. 4, in the static air bearing device 100A according to the second embodiment, the air supply cavity 3A (concave surface 17A) has a rectangular frame shape when viewed from the stacking direction. The air supply cavity 3A (concave surface 17A) has a rectangular frame shape parallel to one side 10a and the other side 10b of the porous plate material 1A.

Furthermore, in the boundary surface 18A of the second embodiment, the corner between the first boundary surface 18a and one side 10a is chamfered to form an arc-shaped R portion 18d. Further, the corner between the second boundary surface 18b and the other side 10b is chamfered to form an arc-shaped R portion 18e.

In the static air bearing device 100A of the second embodiment, no pressure acts in the first direction X1 on the porous plate material 1A from the central portion surrounded by the annular air supply cavity 3A. Therefore, deformation of the porous plate material 1 is suppressed, and the positional accuracy of the bearing surface 11 is improved.

(Embodiment 3)
FIG. 5 is a sectional view of a hydrostatic air bearing device according to Embodiment 3, and more specifically, a sectional view taken along the line VI-VI in FIG. FIG. 6 is a plan view of the hydrostatic air bearing device according to the third embodiment, viewed from the first direction.

As shown in FIG. 6, in the static air bearing device 100B according to the third embodiment, the stepped surface 13B has a triangular shape when viewed from the stacking direction. Therefore, the boundary surface 18B between the bearing surface 11 and the stepped surface 13B has a slope 18f that intersects at 45 degrees with one side 10a and the other side 10b. Further, the corner between the slope 18f and the one side 10a is chamfered to form an arcuate R portion 18g. The corner between the slope 18f and the other side 10b is chamfered to form an arcuate R section 18h.

In the static air bearing device 100B of the third embodiment as well, deformation of the porous plate material 1 is suppressed as in the first embodiment. Therefore, the positional accuracy of the bearing surface 11 is improved.

100, 100A, 100B Static pressure air bearing device 1 Porous plate material 2 Base material 3, 3A Air supply cavity 4 Bolt (fastener)
10 Porous body portion 11 Bearing surface 12 First mating surface 13, 13B Step surface 18, 18A, 18B Boundary surface 18a First boundary surface 18b Second boundary surface 18c, 18d, 18e, 18g, 18h R portion 14 Accommodation hole 15 Bottom surface 16 Through hole 17, 17A Concave surface 20 Base main body portion 21 Second mating surface 22 Bottom surface 23 Air supply port 24 Female screw hole

Claims (4)

porous board material,
a base material overlaid on the porous plate material;
Equipped with
The porous plate material has a bearing surface and a first mating surface that is an opposite surface to the bearing surface,
The base material has a second mating surface that abuts the first mating surface,
An air supply cavity formed by recessing one or both of the first mating surface and the second mating surface is provided between the porous plate material and the base material,
The porous board material and the base material have a rectangular shape when viewed from the stacking direction in which the porous board material and the base material are stacked,
The base material is provided with an air supply port that penetrates in the loading direction and communicates with the air supply cavity,
The air supply cavity has an annular shape when viewed from the loading direction,
The porous plate material and the base material are fastened at four corners by fasteners. The hydrostatic air bearing device. At each corner of the bearing surface,
a stepped surface recessed toward the first mating surface;
a recessed accommodation hole provided in the stepped surface;
a through hole passing through a part of the bottom surface of the accommodation hole and the first mating surface;
has
Each corner of the second mating surface is provided with a female screw hole that overlaps with the through hole when viewed from the loading direction,
The shaft portion of the fastener passes through the through hole and is screwed into the female threaded hole,
The hydrostatic air bearing device according to claim 1, wherein the head of the fastener is disposed in the receiving hole and tightens the bottom surface of the receiving hole toward the base material. The hydrostatic air bearing device according to claim 2, wherein the stepped surface has a rectangular shape when viewed from the loading direction. The hydrostatic air bearing device according to claim 2, wherein the stepped surface has a triangular shape when viewed from the loading direction.

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