Hydrostatic Air Bearing Device

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

[Technical Field]

[0001] The present disclosure relates to an aerostatic bearing device. [Background technology]

[0002] An aerostatic bearing device is a device that generates a thin film of gas between a bearing surface and a supported object. One example of this aerostatic bearing device is one that uses a porous plate material (hereinafter referred to as a porous plate material). In the following patent document, a metal sintered body with a high Young's modulus is used as the porous plate material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-27865 Summary of the Invention [Problem to be solved by the invention]

[0004] In addition to the porous plate, the hydrostatic bearing device also includes a substrate that supports the porous plate, with the porous plate being stacked on the substrate. An air supply cavity is provided between the porous plate and the substrate. In a plan view, the air supply cavity in the above-mentioned patent document is located in the center of the porous plate and has a circular shape. This air supply cavity has a large capacity, and a large pressure acts on the porous plate. Therefore, when the hydrostatic bearing device is driven, the center of the porous plate deforms and protrudes toward the bearing surface.

[0005] The present disclosure has been made in view of the above, and has an object to provide an aerostatic bearing device that can suppress deformation of a porous plate material. [Means for solving the problem]

[0006] In order to achieve the above object, an aerostatic bearing device according to one aspect of the present disclosure includes a porous plate and a substrate overlaid on the porous plate. The porous plate has a bearing surface and a first mating surface opposite the bearing surface. The substrate has a second mating surface that abuts the first mating surface. An air supply cavity is provided between the porous plate and the substrate by recessing one or both of the first mating surface and the second mating surface. An air supply cavity is provided between the first mating surface and the second mating surface by recessing one or both of the first mating surface and the second mating surface. The porous plate and the substrate are rectangular when viewed from a first direction parallel to a perpendicular to the bearing surface. The substrate is provided with an air supply port that penetrates in the first direction and communicates with the air supply cavity. The air supply cavity is annular when viewed from the first direction. The porous plate and the base material are fastened at four corners by fasteners.

[0007] The air intake cavity is annular. In other words, the pressure of the compressed gas does not act on the part of the porous plate facing the central part of the air intake cavity (annular). Therefore, the pressure acting on the porous plate is kept low. In addition, the four corners of the porous plate are fastened with fasteners. Therefore, the fixing strength for fixing the porous plate is high. Therefore, the porous plate is less likely to deform toward the bearing surface.

[0008] Furthermore, the hydrostatic bearing device of the present disclosure has, at each corner of the bearing surface, a stepped surface recessed toward the first mating surface, a recessed accommodating hole provided in the stepped surface, and a through hole penetrating a portion of the bottom surface of the accommodating hole and the first mating surface. Each corner of the second mating surface is provided with an internally threaded hole that overlaps with the through hole when viewed from the loading direction. The shank of the fastener passes through the through hole and screws into the internally threaded hole. The head of the fastener may be disposed in the accommodating hole and tighten the bottom surface of the accommodating hole toward the base material.

[0009] Furthermore, the step surface of the hydrostatic air bearing device of the present disclosure may have a quadrangular shape when viewed from the loading direction.

[0010] Furthermore, the step surface of the hydrostatic air bearing device of the present disclosure may be triangular when viewed from the loading direction. [Effects of the Invention]

[0011] According to the hydrostatic air bearing device of the present disclosure, deformation of the porous plate can be suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view of an externally pressurized air bearing device according to the first embodiment, and more specifically, a cross-sectional view taken along line II in FIG. [Figure 2] FIG. 2 is a plan view of the hydrostatic air bearing device according to the first embodiment, viewed from a first direction. [Figure 3] 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 line IV-IV in FIG. [Figure 4] FIG. 4 is a plan view of the hydrostatic air bearing device according to the second embodiment, viewed from a first direction. [Figure 5] FIG. 5 is a cross-sectional view of an externally pressurized air bearing device according to the third embodiment, and more specifically, a cross-sectional view taken along the line VI-VI in FIG. [Figure 6] FIG. 6 is a plan view of the hydrostatic air bearing device according to the third embodiment, viewed from a first direction. DETAILED DESCRIPTION OF THE INVENTION

[0013] The following detailed description of the preferred embodiments of the present invention will be given with reference to the accompanying drawings. The present disclosure is not limited to the content of the following description. The components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the components described below can be combined as appropriate.

[0014] (Embodiment 1) Fig. 1 is a cross-sectional view of an externally pressurized air bearing device according to embodiment 1, and more specifically, a cross-sectional view taken along line II in Fig. 2. Fig. 2 is a plan view of the externally pressurized air bearing device according to embodiment 1 as viewed from a first direction. As shown in Fig. 1, the externally pressurized air bearing device 100 includes a porous plate 1, a base material 2, and four bolts (fasteners) 4.

[0015] In the following description, the direction in which the porous plate 1 and the substrate 2 overlap is referred to as the stacking direction. Within the stacking direction, the direction in which the porous plate 1 is arranged as viewed from the substrate 2 is referred to as the first direction X1. The direction opposite to the first direction is referred to as the second direction X2.

[0016] The porous plate 1 is made by molding a porous material (such as graphite, ceramics, or a sintered metal powder) into a plate shape, which has many pores that serve as gas passageways. The porous plate 1 includes a porous main body 10, a bearing surface 11 facing in a first direction X1, and a first mating surface 12 facing in a second direction X2.

[0017] 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 a right angle. The bearing surface 11 is a flat surface that faces the object to be supported. Each of the four corners of the bearing surface 11 has a step surface 13 that is recessed in the second direction X2 from the bearing surface 11.

[0018] The step surface 13 has a rectangular shape when viewed from the first direction X1. A boundary surface 18 extending in the stacking direction is provided between the bearing surface 11 and the step 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 perpendicular to the first boundary surface 18a. 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.

[0019] As shown in FIG. 1, a circular accommodating hole 14 is provided in the step surface 13. A through-hole 16 penetrating in the second direction X2 is provided in a bottom surface 15 of the accommodating hole 14. The first mating surface 12 is flat. The first mating surface 12 is provided with a concave surface 17 recessed in the first direction X1. As shown in FIG. 2, the concave surface 17 is an annular groove. The concave surface 17 is circular, with the central portion P of the porous main body 10 as the center.

[0020] As shown in FIG. 1, the substrate 2 is a base plate that supports the porous plate 1. The substrate 2 has a substrate main body 20, a second mating surface 21 facing in the first direction X1, and a bottom surface 22 facing in the second direction X2. The substrate main body 20 has a square shape when viewed from the stacking direction and is the same shape as the porous plate 1. The second mating surface 21 abuts against the first mating surface 12 of the porous plate 1. The second mating surface 21 covers the concave surface 17 from the second direction X2. As a result, the internal space of the concave surface 17 becomes the annular air supply cavity 3.

[0021] 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 may be provided with the concave surface 17 to form the air supply cavity 3. Alternatively, the first mating surface 12 and the second mating surface 21 may both be provided with the concave surfaces 17 to form the air supply cavity 3.

[0022] The base material main body 20 is provided with a circular air inlet 23 that penetrates in the stacking direction. When viewed from the stacking direction, the air inlet 23 overlaps with the air inlet cavity 3. Thus, compressed air is supplied to the air inlet cavity 3 through the air inlet 23. A female threaded hole 24 is provided in each of the four corners of the second mating surface 21. When viewed from the stacking direction, the female threaded holes 24 overlap with the through holes 16.

[0023] The bolt 4 has a shaft 40 with a threaded outer surface and a head 41 provided at the end of the shaft 40 in the first direction X1. The shaft 40 of the bolt 4 is inserted into the through hole 16 and threadedly engages with the female threaded hole 24. The head 41 of the bolt 4 fastens the bottom surface 15 of the accommodation hole 14 in the second direction X2. This integrates the porous plate 1 and the substrate 2. The head 41 of the bolt 4 is accommodated in the accommodation hole 14 and does not protrude beyond the step surface 13 in the first direction X1.

[0024] As described above, according to the hydrostatic bearing device 100 of the first embodiment, when compressed air is supplied to the air supply cavity 3 from the air supply port 23, the compressed air in the air supply cavity 3 passes through the porous plate 1 and is ejected from the bearing surface 11. As a result, a thin film of gas is generated on the bearing surface 11.

[0025] Furthermore, pressure acts on the porous plate 1 from the air supply cavity 3 in the first direction X1. Here, the air supply cavity 3 is annular, and pressure in the first direction X1 does not act on the central portion surrounded by the annular shape of the air supply cavity 3. Therefore, the pressure acting on the porous plate 1 is kept small. Furthermore, because the porous plate 1 is fastened with four bolts (fasteners) 4, it is difficult for the porous plate 1 to deform in the stacking direction. Therefore, when the hydrostatic air bearing device 100 is driven, the porous plate 1 does not deform so as to protrude in the first direction X1. This improves the positional accuracy of the bearing surface 11. Furthermore, because the porous plate 1 does not deform, the amount of air ejected from the bearing surface 11 is uniform at each portion of the bearing surface 11, enabling stable bearing performance to be achieved.

[0026] As described above, the hydrostatic bearing device 100 of the first embodiment includes a porous plate 1 and a substrate 2 that is placed on the porous plate 1. The porous plate 1 has a bearing surface 11 and a first mating surface 12 that is the surface opposite the bearing surface 11. The substrate 2 has a second mating surface 21 that abuts against the first mating surface 12. An air supply cavity 3 is provided between the porous plate 1 and the substrate 2 by recessing one or both of the first mating surface 12 and the second mating surface 21. The porous plate 1 and the substrate 2 have a rectangular shape when viewed from the stacking direction in which the porous plate 1 and the substrate 2 are stacked. The substrate 2 has an air supply port 23 that penetrates in the stacking direction and communicates with the air supply cavity 3. The air supply cavity 3 has a ring shape when viewed from the stacking direction. The porous plate 1 and the substrate 2 are fastened at their four corners with fasteners (bolts 4).

[0027] According to this embodiment, it is possible to prevent the porous plate 1 from deforming so as to protrude in the first direction X1.

[0028] Furthermore, in the hydrostatic air bearing device 100 of Embodiment 1, each corner of the bearing surface 11 has a stepped surface 13 recessed toward the first mating surface 12, a recessed accommodation hole 14 provided in the stepped surface 13, and a through-hole 16 penetrating a portion of the bottom surface 15 of the accommodation hole 14 and the first mating surface 12. Each corner of the second mating surface 21 has an internally threaded hole 24 that overlaps with the through-hole 16 when viewed from the loading direction. A shank 40 of a fastener passes through the through-hole 16 and screws into the internally threaded hole 24. A head 41 of the fastener is disposed in the accommodation hole 14 and tightens the bottom surface 15 of the accommodation hole 14 toward the substrate 2. Next, Embodiments 2 and 3, which are partial modifications of the hydrostatic air bearing device 100 of Embodiment 1, will be described. The following explanation will focus on the differences from Embodiment 1.

[0029] (Embodiment 2) Fig. 3 is a cross-sectional view of the externally pressurized air bearing device according to embodiment 2, and more specifically, a cross-sectional view taken along line IV-IV in Fig. 4. Fig. 4 is a plan view of the externally pressurized air bearing device according to embodiment 2 as seen from a first direction.

[0030] 4, in the hydrostatic 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 that is parallel to one side 10a and the other side 10b of the porous plate 1A.

[0031] 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 rounded portion 18d, and the corner between the second boundary surface 18b and the other side 10b is chamfered to form an arc-shaped rounded portion 18e.

[0032] In the hydrostatic bearing device 100A of the second embodiment, pressure is not applied to the porous plate 1A in the first direction X1 from the central portion surrounded by the annular air supply cavity 3A, which suppresses deformation of the porous plate 1A and improves the positional accuracy of the bearing surface 11.

[0033] (Embodiment 3) Fig. 5 is a cross-sectional view of an externally pressurized air bearing device according to a third embodiment, and more specifically, a cross-sectional view taken along the line VI-VI in Fig. 6. Fig. 6 is a plan view of the externally pressurized air bearing device according to the third embodiment, viewed from a first direction.

[0034] As shown in Fig. 6, in an externally pressurized air bearing device 100B according to the third embodiment, the stepped surface 13B has a triangular shape when viewed in the stacking direction. Therefore, a boundary surface 18B between the bearing surface 11 and the stepped surface 13B has a slope 18f that intersects with each of the sides 10a and 10b at a 45° angle. The corner where the slope 18f meets the side 10a is chamfered to form an arc-shaped rounded portion 18g. The corner where the slope 18f meets the side 10b is chamfered to form an arc-shaped rounded portion 18h.

[0035] In the hydrostatic air bearing device 100B of the third embodiment, deformation of the porous plate 1 is suppressed, as in the first embodiment, and therefore the positional accuracy of the bearing surface 11 is improved. [Explanation of symbols]

[0036] 100, 100A, 100B Hydrostatic Air Bearing Device 1 Porous plate material 2 Base material 3, 3A Air Intake Cavity 4 bolts (fasteners) 10 Porous body 11 Bearing surface 12 First mating surface 13, 13B Step surface 18, 18A, 18B interface 18a 1st boundary surface 18b Second boundary surface 18c, 18d, 18e, 18g, 18h R section 14 Storage Cave 15 bottom 16 through holes 17, 17A concave 20 Base material main body part 21 Second mating surface 22 bottom 23 Air supply port 24 female threaded holes

Claims

1. A porous plate material; A substrate that is overlaid on the porous plate material; Equipped with The porous plate 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 against the first mating surface, An air supply cavity is provided between the porous plate and the base material by recessing one or both of the first mating surface and the second mating surface, The porous plate and the substrate have a rectangular shape when viewed from the stacking direction in which the porous plate and the substrate are stacked, The base material is provided with an air supply port that penetrates in the stacking 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 and the base material are fastened at four corners by fasteners, At each corner of the bearing surface: a step surface recessed toward the first mating surface; a recessed receiving hole provided on the step surface; a through hole penetrating a portion of a bottom surface of the accommodation hole and the first mating surface; and 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, a shaft portion of the fastener passes through the through hole and is threaded into the female threaded hole; The head of the fastener is placed in the receiving hole and tightens the bottom surface of the receiving hole toward the base material. Hydrostatic air bearing device.

2. The step surface has a rectangular shape when viewed from the loading direction.

2. The hydrostatic air bearing device according to claim 1.

3. The step surface has a triangular shape when viewed from the loading direction.

2. The hydrostatic air bearing device according to claim 1.

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