Static gas bearing

Abstract

To provide a hydrostatic gas bearing having a fixed structure that can maximize the bearing surface area. [Solution] The hydrostatic gas bearing comprises a porous plate material and a housing on which the porous plate material is loaded. The porous plate material has a bearing surface and a porous plate material side mating surface which is the opposite surface to the bearing surface. The housing has a housing side mating surface that abuts the porous plate material side mating surface and an outer peripheral wall portion that protrudes in the loading direction from the outer peripheral edge of the housing side mating surface over its entire circumference and covers the outer peripheral surface of the porous plate material. The outer peripheral wall portion has a locking groove formed on the inner peripheral surface of the outer peripheral wall portion so as to extend in the circumferential direction, or a locking hole that penetrates from the inner peripheral surface to the outer peripheral surface of the outer peripheral wall portion. The porous plate material is fixed to the housing by a locking member that engages with the locking groove or locking hole.

Description

Technical Field

[0004] , , , , , , , , ,

[0005] , , , , ,

[0001] The present invention relates to a hydrostatic gas bearing.

Background Art

[0002] In machine tools, semiconductor manufacturing devices, etc. that require high guiding accuracy, hydrostatic gas bearings may be used. A hydrostatic gas bearing is a device that generates a thin film of gas between a bearing surface and an object to be supported. Since the object to be supported is supported in a non-contact state with the bearing surface, it is possible to position the object to be supported with high accuracy. As an example of this hydrostatic gas bearing, there is one that uses a porous plate material (hereinafter referred to as a porous plate material) as described in Patent Document 1.

[0003] FIG. 10 is a plan view of a hydrostatic gas bearing according to a conventional example. FIG. 11 is a cross-sectional view of a hydrostatic gas bearing according to a conventional example. The hydrostatic gas bearing described in Patent Document 1 includes a main body 111 and a circular porous plate material 113 as shown in FIGS. 10 and 11. Further, the main body 111 has a female screw 120 at the center, and the porous plate material 113 has a through hole 124 at the center. In the hydrostatic gas bearing according to the conventional example, the main body 111 and the porous plate material 113 are fixed to each other by a bolt 125 passing through the center of each, and the bolt 125 is screwed into the female screw 120 of the main body 111.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the case of a structure in which a bolt 125 is provided at the center of the porous plate material 113 as in the hydrostatic gas bearing described in Patent Document 1, gas cannot be discharged at the center of the bearing surface 115, which may affect the object support performance of the hydrostatic gas bearing.

[0006] The present invention has been made in view of the above problems, and its objective is to provide a hydrostatic gas bearing having a fixed structure that can maximize the bearing surface area. [Means for solving the problem]

[0007] The above objective of the present invention is achieved by the following configuration. (1) Porous plate material and A housing on which the porous plate material is stacked, A hydrostatic gas bearing comprising, The porous plate material has a bearing surface and a porous plate material side mating surface which is the opposite side of the bearing surface. The housing has a housing-side mating surface that abuts against the porous plate material-side mating surface, and an outer peripheral wall portion that protrudes in the loading direction from the outer peripheral edge of the housing-side mating surface over its entire circumference and covers the outer peripheral surface of the porous plate material. The outer peripheral wall portion has a locking groove formed on the inner peripheral surface of the outer peripheral wall portion so as to extend in the circumferential direction, or a locking hole that penetrates from the inner peripheral surface to the outer peripheral surface of the outer peripheral wall portion. The porous plate material is fixed to the housing by a locking member that engages with the locking groove or the locking hole. A hydrostatic gas bearing characterized by the following features. (2) Porous plate material and A housing on which the porous plate material is stacked, A hydrostatic gas bearing comprising, The porous plate material has a bearing surface and a porous plate material side mating surface which is the opposite side of the bearing surface. The housing has a housing-side mating surface that abuts against the porous plate material-side mating surface, and an outer peripheral wall portion that protrudes in the loading direction from the outer peripheral edge of the housing-side mating surface over its entire circumference and covers the outer peripheral surface of the porous plate material. The outer peripheral wall portion has a groove-shaped housing-side air pocket formed over the entire circumference of the inner surface of the outer peripheral wall portion. The porous plate material has a porous plate material side air pocket formed by recessing a portion of its outer surface, and the position of the housing side air pocket overlaps with that of the housing side air pocket in the loading direction in at least a portion of the way. A hydrostatic gas bearing characterized by the following features. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a hydrostatic gas bearing having a fixed structure that can maximize the bearing surface area. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a cross-sectional view of a hydrostatic gas bearing according to the first embodiment. [Figure 2] Figure 2 is an exploded cross-sectional view of a hydrostatic gas bearing according to the first embodiment. [Figure 3] Figure 3 is a cross-sectional view taken along the line III-III in Figure 1. [Figure 4] Figure 4(a) is a plan view of the retaining ring according to the first embodiment, viewed from the loading direction. Figure 4(b) is a plan view of the retaining ring according to modification 1 of the first embodiment, viewed from the loading direction. Figure 4(c) is a plan view of the spacer according to modification 2 of the first embodiment, viewed from the loading direction. [Figure 5] Figure 5 is a cross-sectional view of a hydrostatic gas bearing according to a modified example 2 of the first embodiment. [Figure 6] Figure 6 is a cross-sectional view of a hydrostatic gas bearing according to the second embodiment. [Figure 7] Figure 7 is a cross-sectional view of the porous plate material at the position indicated by the line VII-VII in Figure 6. [Figure 8] Figure 8 is a cross-sectional view of a hydrostatic gas bearing according to the third embodiment. [Figure 9] Figure 9 shows a cross-sectional view taken along the line IX-IX in Figure 8, and the flow of compressed air. [Figure 10] Figure 10 is a plan view of a conventional hydrostatic gas bearing. [Figure 11] Figure 11 is a cross-sectional view of a conventional hydrostatic gas bearing.

Best Mode for Carrying Out the Invention

[0010] (First Embodiment) Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. FIG. 1 is a cross-sectional view of a static pressure gas bearing according to the first embodiment. FIG. 2 is an exploded cross-sectional view of the static pressure gas bearing according to the first embodiment. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1. As shown in FIGS. 1 and 2, the static pressure gas bearing 1 according to the present embodiment includes a porous plate material 10 and a housing 20 on which the porous plate material 10 is loaded. In the following description, the direction in which the porous plate material 10 and the housing 20 overlap is referred to as the loading direction. The direction in which the porous plate material 10 is disposed as viewed from the housing 20 in the loading direction (the upper side in FIG. 1) is referred to as one side of the loading direction. The side opposite to one side of the loading direction (the lower side in FIG. 1) is referred to as the other side of the loading direction. Further, in the present embodiment, the porous plate material 10 and the housing 20 are circular when viewed from the loading direction. A central axis extending in the loading direction and passing through the centers of the circular porous plate material 10 and the housing 20 when viewed from the loading direction is denoted as О, and the direction away from the central axis О is referred to as the radially outer side. Also, the direction approaching the central axis О (the opposite side of the radially outer side) is referred to as the radially inner side.

[0011] The porous plate material 10 is made of a porous material such as a graphite material, a carbon material, ceramics, or a metal powder sintered body, and is formed into a plate shape. The porous plate material 10 has a bearing surface 11 and a porous plate material side mating surface 12 that is the opposite surface of the bearing surface 11. The bearing surface 11 is a plane facing a support object (not shown), and supports the support object (not shown) by ejecting compressed air supplied through an air supply port 23 and an air supply cavity 2 described later.

[0012] The outer peripheral surface of the porous plate has a large-diameter portion 13 and a small-diameter portion 14 formed with a smaller diameter than the large-diameter portion 13. The large-diameter portion 13 has an end portion on the other side in the loading direction connected to the mating surface 12 on the porous plate side and is formed in a cylindrical surface shape. The small-diameter portion 14 has an end portion on the other side in the loading direction connected to the large-diameter portion 13 and an end portion on the one side in the loading direction connected to the bearing surface 11. The small-diameter portion 14 is formed in a conical surface shape that inclines so as to reduce the diameter as it approaches the bearing surface 11, that is, as it goes toward the one side in the loading direction.

[0013] The housing 20 has a housing mating surface 21 on which the porous plate 10 is loaded and which abuts against the mating surface 12 on the porous plate side of the porous plate 10, and a bottom surface 22 that is the opposite surface of the housing mating surface 21.

[0014] As shown in FIGS. 1 to 3, in the hydrostatic gas bearing 1, a recess 3 is formed in the housing 20 such that the housing mating surface 21 is recessed on the other side in the loading direction. By stacking the porous plate 10 on the housing mating surface 21, an air supply cavity 2 is formed in the space surrounded by the recess 3 and the mating surface 12 on the porous plate side. Further, the air supply cavity 2 according to the present embodiment is formed in an annular shape when viewed from the loading direction, and the cross section perpendicular to the circumferential direction is rectangular. Note that the air supply cavity 2 may be formed by recessing one or both of the mating surface 12 on the porous plate side and the housing mating surface 21 in the loading direction. Further, the shape of the air supply cavity 2 when viewed from the loading direction is not limited to an annular shape, and may be a rectangular annular shape or the like.

[0015] The housing 20 is provided with an air supply port 23 that penetrates the housing 20 in the loading direction and communicates with the air supply cavity 2. The air supply port 23 is a hole whose inner surface is formed in a cylindrical surface shape from the bottom surface 22 of the housing 20 to the air supply cavity 2. Particularly, as shown in FIG. 3, when viewed from the loading direction, the diameter R of the air supply port 23 is larger than the radial width W of the air supply cavity 2, and the central portion of the air supply port 23 is formed so as to overlap the air supply cavity 2. Compressed air for operating the hydrostatic gas bearing 1 is supplied to the air supply cavity 2 through the air supply port 23.

[0016] As shown in Figures 1 and 2, the housing 20 has an outer peripheral wall portion 31 that protrudes in the loading direction from the outer peripheral edge of the housing-side mating surface 21 over its entire circumference. The outer peripheral wall portion 31 is formed in a cylindrical shape, and the height of the outer peripheral wall portion 31 in the loading direction is equal to the thickness of the porous plate material 10 in the loading direction. As a result, when the hydrostatic gas bearing 1 is viewed from the radial direction, the outer peripheral wall portion 31 is formed to cover the outer peripheral surface of the porous plate material 10. Furthermore, the inner peripheral surface of the outer peripheral wall portion 31 and the cylindrical large-diameter portion 13 of the porous plate material 10 can come into contact. The conical small-diameter portion 14 does not come into contact with the inner peripheral surface of the outer peripheral wall portion 31.

[0017] The outer peripheral wall portion 31 has a locking groove 32 recessed radially outward on its inner peripheral surface. The locking groove 32 extends circumferentially on the inner peripheral surface of the outer peripheral wall portion 31 and is formed over its entire circumference. In this embodiment, the position of the locking groove 32 in the loading direction is formed between one end and the other end of the small diameter portion 14 of the porous plate material 10 in the loading direction. Furthermore, the cross-section of the locking groove 32 perpendicular to the circumferential direction is U-shaped, and the width of the locking groove 32 in the loading direction is greater than the thickness of the locking members (retaining rings 40, 45 and spacers 50) described later in the loading direction, and smaller than the dimensions of the small diameter portion 14 of the porous plate material 10 in the loading direction. A portion of the retaining ring 40 described later engages with the locking groove 32 in the circumferential direction. Therefore, the locking groove 32 does not have to be formed over the entire circumference of the inner surface of the outer peripheral wall portion 31, but may be formed on a part of the inner surface of the outer peripheral wall portion 31 so as to extend in the circumferential direction.

[0018] Figure 4(a) is a plan view of the retaining ring according to the first embodiment, viewed from the loading direction. Figure 4(b) is a plan view of the retaining ring according to modification 1 of the first embodiment, viewed from the loading direction. Figure 4(c) is a plan view of the spacer according to modification 2 of the first embodiment, viewed from the loading direction.

[0019] As shown in Figures 1, 2, and 4(a), the porous plate material 10 according to the first embodiment is fixed to the housing 20 by a retaining ring 40, which is a locking member that engages with a locking groove 32. The retaining ring 40 is preferably made of spring steel, such as SK material (carbon tool steel). The retaining ring 40 has a substantially C-shape when viewed from the loading direction and has an opening 44 defined by two retaining ring ends 41, 41 in a part of the circumferential direction of the retaining ring 40. The retaining ring 40 also has a circumferential central portion 42 located between the retaining ring ends 41, 41 and in the circumferential center of the retaining ring 40. The cross-section of the retaining ring 40 perpendicular to the circumferential direction is rectangular.

[0020] The retaining ring 40 is positioned on the outer circumference of the small-diameter portion 14 of the porous plate material 10. In this embodiment, at least at the circumferential center portion 42, the other end of the inner surface of the retaining ring 40 in the loading direction contacts the small-diameter portion 14 of the porous plate material 10. In this embodiment, near the circumferential center portion 42, the other end of the inner surface of the retaining ring 40 in the loading direction makes line contact with the small-diameter portion 14 of the porous plate material 10 along the circumferential direction. In addition, at least at the circumferential center portion 42, one side of the retaining ring 40 in the loading direction can abut against the one end face in the loading direction of the locking groove 32, thereby preventing it from coming out of the housing 20. Furthermore, the retaining ring 40 only needs to be able to restrict the movement of the porous plate material 10 to one side in the loading direction, the retaining ring 40 and the porous plate material 10 only need to be in contact at any position in the circumferential direction, and the retaining ring 40 and the locking groove 32 only need to be engaged at any position in the circumferential direction.

[0021] Furthermore, the retaining ring 40 is elastic, and the outer diameter of the retaining ring 40 changes slightly as the circumferential width of the opening 44 changes. Holes 43, 43 are formed at the ends 41, 41 of the retaining ring, penetrating through the ends 41, 41 in the loading direction. The holes 43, 43 are for inserting the tip of a retaining ring mounting tool when assembling the retaining ring 40 into the housing 20.

[0022] To assemble the hydrostatic gas bearing 1, with the porous plate material 10 placed on the housing 20, a retaining ring mounting tool such as snap ring pliers is inserted into the holes 43, 43 of the retaining ring 40, and the retaining ring 40 is inserted into the space between the outer peripheral wall portion 31 and the small diameter portion 14 of the porous plate material 10 while reducing its diameter. Once the retaining ring 40 is incorporated into the hydrostatic gas bearing 1, it expands again and engages with the locking groove 32.

[0023] According to the first embodiment of the hydrostatic gas bearing 1, compressed air is supplied from the air inlet 23 to the air intake cavity 2, and then passed through the porous plate material 10 and injected from the bearing surface 11. As a result, a thin film of gas is formed on the bearing surface 11, and the object to be supported (not shown) can be supported in a non-contact manner.

[0024] By using a retaining ring 40 that contacts the outer surface of the porous plate material 10, the area of ​​the bearing surface 11 can be maximized while fixing the porous plate material 10 to the housing 20. Furthermore, since the retaining ring 40 is easy to attach and detach, the assembly of the hydrostatic gas bearing 1 is improved, and it becomes easier to replace only the porous plate material 10 if deterioration or damage occurs.

[0025] As described above, the hydrostatic gas bearing 1 according to the first embodiment has a locking groove 32 in the outer peripheral wall portion 31 of the housing 20, and the porous plate material 10 is fixed to the housing by a locking member (retaining ring 40) that engages with the locking groove 32. This maximizes the bearing surface area of ​​the hydrostatic gas bearing 1 and improves ease of assembly, etc.

[0026] The following describes a modified example of the hydrostatic gas bearing according to the first embodiment. As shown in Figure 4(b), a retaining ring 45 may be used as the locking member for fixing the porous plate material 10 to the housing 20. The retaining ring 45 has a substantially C-shape when viewed from the loading direction, and its cross-section perpendicular to the circumferential direction is rectangular. The retaining ring 45 has bent portions 48, 48 at its ends 46, 46 that bend radially inward. The tip of a retaining ring mounting tool can be engaged with the bent portions 48, 48, and the retaining ring 45 can be assembled into the housing 20 while reducing its diameter. With the retaining ring 45, at least the central portion 47 in the circumferential direction can contact the small-diameter portion 14 of the porous plate material 10 and engage with the locking groove 32, thereby fixing the porous plate material 10 to the housing 20.

[0027] Figure 5 is a cross-sectional view of a hydrostatic gas bearing according to a modified example 2 of the first embodiment. As shown in Figures 4(c) and 5, the hydrostatic gas bearing 1 may have a spacer 50, which is an annular member, provided on the other side in the loading direction from the retaining ring 40 (retaining ring 45). The spacer 50 is positioned to contact the small-diameter portion 14 of the porous plate material 10 and the other side of the retaining ring 40 (retaining ring 45) in the loading direction. The spacer 50 also contacts the entire circumference of the small-diameter portion 14 of the porous plate material 10. This allows the porous plate material 10 to be stably fixed by the retaining ring 40 (retaining ring 45) and the spacer 50. In the example shown in Figure 5, the outer diameter of the spacer 50 is larger than the diameter of the inner surface of the portion of the outer peripheral wall 31 where the locking groove 32 is not formed. In this case, although not shown, it is also possible to provide a slit in a part of the circumferential direction of the spacer 50 to facilitate assembly into the locking groove 32. Furthermore, the outer diameter of the spacer 50 may be smaller than the diameter of the inner surface of the portion of the outer peripheral wall 31 where the locking groove 32 is not formed. Additionally, an O-ring or the like may be used instead of the spacer 50.

[0028] Furthermore, the small-diameter portion 14 of the porous plate material 10 only needs to be able to contact the retaining ring 40, and may consist of a radially extending plane and a cylindrical surface extending in the loading direction, and may have a shape that forms a step with the large-diameter portion 13. In this case, the retaining ring 40 contacts the radially extending plane of the small-diameter portion 14.

[0029] Furthermore, adhesive may be applied between the mating surface 12 on the porous plate side and the mating surface 21 on the housing side to bond the porous plate 10 and the housing 20, and then a locking member such as the aforementioned retaining ring 40 may be used in combination.

[0030] (Second embodiment) A second embodiment of the present invention will be described below. Note that the same configuration as that of the hydrostatic gas bearing according to the first embodiment will not be described. Figure 6 is a cross-sectional view of the hydrostatic gas bearing according to the second embodiment. Figure 7 is a cross-sectional view of the porous plate material at the position indicated by the line VII-VII in Figure 6. As shown in Figure 6, the outer peripheral wall portion 31 of the hydrostatic gas bearing 1 according to this embodiment has a locking hole 34 that penetrates from the inner peripheral surface to the outer peripheral surface of the outer peripheral wall portion 31, and the porous plate material 10 is fixed to the housing 20 by a locking member that engages with the locking hole 34.

[0031] As shown in Figures 6 and 7, the porous plate material 10 according to this embodiment has two porous plate material-side locking holes 15 formed radially inward from the large diameter portion 13 that constitutes the outer circumferential surface. The porous plate material-side locking holes 15 have an inner surface formed in the shape of a cylindrical surface that extends radially. Furthermore, the two porous plate material-side locking holes 15 are formed at positions where the central axes of the porous plate material-side locking holes 15 are perpendicular to each other. In particular, as shown in Figure 6, the large diameter portion 13 according to this embodiment is formed to be longer in the loading direction than the large diameter portion 13 according to the first embodiment. Accordingly, the small diameter portion 14 according to this embodiment is formed to be shorter in the loading direction than the small diameter portion 14 according to the first embodiment. Here, the small diameter portion 14 serves as a chamfered surface, contributing to the prevention of damage to the porous plate material 10.

[0032] Furthermore, as shown in Figure 6, the locking hole 34 in this embodiment is a threaded hole extending in the radial direction. The locking member is a threaded member 60, which has a threaded base 61 that screws into the outer peripheral wall 31. The threaded member 60 has a tip 62 that protrudes radially inward from the inner circumferential surface of the outer peripheral wall 31 and engages with the porous plate material side locking hole 15. The tip 62 is connected to the base 61 and has a cylindrical shape. The tip 62 only needs to prevent the porous plate material 10 from coming out to one side in the loading direction, and the accuracy of the outer diameter is not required as long as it can engage with the porous plate material side locking hole 15. Note that the threaded member 60 of the locking member and the locking hole 34 may have inner circumferential surfaces that are not threaded, but rather formed in a cylindrical shape. That is, the locking member may be a pin member that fits into the locking hole 34 of the outer peripheral wall 31.

[0033] The same number of locking holes 15 and 34 are formed on the porous plate side so that their circumferential positions overlap. In this embodiment, the porous plate 10 has two porous plate side locking holes 15, and the outer peripheral wall portion 31 has two locking holes 34. The porous plate side locking holes 15 and 34 are arranged to communicate with each other. Note that it is sufficient that at least one of each of the porous plate side locking holes 15 and 34 is formed, and the number and position of the porous plate side locking holes 15 and 34 are not specified, as long as their circumferential positions overlap and the same number of them are arranged to communicate with each other.

[0034] As described above, in the hydrostatic gas bearing 1 according to the second embodiment, the porous plate material 10 is fixed to the housing 20 by inserting a locking member (screw member 60 or pin member) into the locking hole 34 of the outer peripheral wall portion 31 and engaging it with the porous plate material 10. As in the conventional example shown in Figures 10 and 11, when the bolt 125 is located in the center of the bearing surface 115, the area of ​​the bearing surface 11 can be maximized by using a screw member 60 or pin member that is inserted radially into the porous plate material 10, rather than using a bolt that penetrates in the loading direction. Furthermore, since the pin member is easier to attach and detach than a bolt, the assembly of the hydrostatic gas bearing 1 is improved.

[0035] (Third embodiment) A third embodiment of the present invention will be described below. Note that the same configuration as that of the hydrostatic gas bearing according to the above-described embodiment will not be described. Figure 8 is a cross-sectional view of the hydrostatic gas bearing according to the third embodiment. Figure 9 is a cross-sectional view taken along the line IX-IX in Figure 8 and a diagram showing the flow of compressed air. As shown in Figures 8 and 9, the outer peripheral wall portion 31 of the housing 20 according to this embodiment has a housing-side air pocket 36 recessed radially outward on its inner circumferential surface. The housing-side air pocket 36 extends circumferentially on the inner circumferential surface of the outer peripheral wall portion 31 and is formed over its entire circumference. The porous plate material 10 has a porous plate material-side air pocket 16 formed by recessing a part of the outer peripheral surface of the porous plate material 10. The porous plate material 10 according to this embodiment is fixed to the housing 20 by the flow of compressed air supplied to the entire porous plate material 10 from the air supply port 23 through the air supply cavity 2.

[0036] The housing-side air pocket 36 is formed between one end of the large-diameter portion 13 of the porous plate material 10 in the loading direction and the other end in the loading direction. Furthermore, the cross-section of the housing-side air pocket 36 perpendicular to the circumferential direction is U-shaped.

[0037] The porous plate material 10 has three porous plate material-side air pockets 16 formed radially inward from the large-diameter portion 13 that constitutes the outer circumferential surface. The porous plate material-side air pockets 16 have an inner surface formed in a cylindrical shape that extends radially. The three porous plate material-side air pockets 16 are arranged at equal intervals in the circumferential direction. In particular, as shown in Figure 8, the large-diameter portion 13 in this embodiment is formed to be longer in the loading direction than the large-diameter portion 13 in the first embodiment. Accordingly, the small-diameter portion 14 in this embodiment is formed to be shorter in the loading direction than the small-diameter portion 14 in the first embodiment.

[0038] Furthermore, it is preferable that the diameter of the porous plate side air pocket 16 be larger than the width of the housing side air pocket 36 in the loading direction. Also, the porous plate side air pocket 16 is formed at a position where its position in the loading direction overlaps with that of the housing side air pocket 36 in at least a portion of the way. Note that the shape of the porous plate side air pocket 16 is not limited to a cylindrical shape, and may have a rectangular cross-section. In addition, the number and position of the porous plate side air pocket 16 can be changed as desired.

[0039] In the hydrostatic gas bearing 1 according to this embodiment, compressed air is supplied from the air inlet 23 to the air intake cavity 2 and injected to the outside of the porous plate material 10 from the bearing surface 11 and the porous plate material side air pocket 16. The arrows shown in Figure 9 indicate the flow of compressed air injected from the porous plate material side air pocket 16. A portion of the compressed air supplied to the air intake cavity 2 flows radially outward from the porous plate material 10 through the outer circumferential surface of the air intake cavity 2, as shown by arrow A. The compressed air around the porous plate material side air pocket 16 then flows into the porous plate material side air pocket 16, as shown by arrows B, B', B''. The compressed air supplied to the porous plate material side air pocket 16 flows outward from the porous plate material side air pocket 16, as shown by arrow C, and is supplied to the housing side air pocket 36. Subsequently, the compressed air flows circumferentially along the large-diameter portion 13 of the porous plate material 10, passing through the housing-side air pocket 36 as shown by arrows D and D', and then is released from the bearing surface 11 via the large-diameter portion 13 of the porous plate material 10, as shown by arrow E.

[0040] The porous plate side air pocket 16 is recessed radially inward from the outer surface of the porous plate 10, so that the interface between the inside and outside of the porous plate 10 is located at a position where compressed air directed radially outward from the porous plate 10, as shown by arrow A, can easily reach it. In addition, the porous plate side air pocket 16 locally increases the surface area of ​​the interface between the inside and outside of the porous plate 10. As a result, compressed air near the porous plate side air pocket 16 inside the porous plate 10 can easily flow into the porous plate side air pocket 16, creating the compressed air flow described above.

[0041] Due to the compressed air flow described above, the pressure increases in the air pocket 16 on the porous plate side and the air pocket 36 on the housing side, causing the porous plate 10 to receive a force directed toward the other side in the loading direction and to be fixed to the housing 20.

[0042] According to the hydrostatic gas bearing 1 of the third embodiment, the porous plate material 10 can be fixed to the housing 20 with a simple structure without using fixing members, and the area of ​​the bearing surface 11 can be maximized.

[0043] The present invention is not limited to those exemplified in the above embodiments, and can be modified as appropriate without departing from the spirit of the invention.

[0044] As described above, the following matters are disclosed in this specification: (1) Porous plate material and A housing on which the porous plate material is stacked, A hydrostatic gas bearing comprising, The porous plate material has a bearing surface and a porous plate material side mating surface which is the opposite side of the bearing surface. The housing has a housing-side mating surface that abuts against the porous plate material-side mating surface, and an outer peripheral wall portion that protrudes in the loading direction from the outer peripheral edge of the housing-side mating surface over its entire circumference and covers the outer peripheral surface of the porous plate material. The outer peripheral wall portion has a locking groove formed on the inner peripheral surface of the outer peripheral wall portion so as to extend in the circumferential direction, or a locking hole that penetrates from the inner peripheral surface to the outer peripheral surface of the outer peripheral wall portion. The porous plate material is fixed to the housing by a locking member that engages with the locking groove or the locking hole. A hydrostatic gas bearing characterized by the following features. This configuration provides a hydrostatic gas bearing with a fixed structure that maximizes the bearing surface area.

[0045] (2) The outer surface of the porous plate material has a cylindrical large-diameter portion connected to the mating surface on the porous plate material side, and a small-diameter portion formed to be smaller in diameter than the large-diameter portion and connected to the bearing surface, The locking member is a retaining ring having a substantially C-shape and fitted into the locking groove, The retaining ring is positioned on the outer circumference of the small-diameter portion of the porous plate material. The static gas bearing according to (1), characterized in that it is a static gas bearing. This configuration allows for maximizing the bearing surface area while securing the porous plate material to the housing. Furthermore, the retaining ring is easy to attach and detach, improving the ease of assembly of the hydrostatic gas bearing and making it easier to replace the porous plate material when it deteriorates or breaks.

[0046] (3) The small-diameter portion of the porous plate material is a conical surface that is inclined to decrease in diameter as it approaches the bearing surface in the loading direction, The retaining ring is capable of contacting the small diameter portion. The static gas bearing according to (2), characterized in that This configuration allows for maximizing the bearing surface area while securing the porous plate material to the housing. Furthermore, the retaining ring is easy to attach and detach, improving the ease of assembly of the hydrostatic gas bearing and making it easier to replace the porous plate material when it deteriorates or breaks.

[0047] (4) The retaining ring is provided on the other side in the loading direction and further has an annular member that can come into contact with the small diameter portion. A static gas bearing according to (2) or (3), characterized in that... This configuration allows the porous plate material to be more stably fixed to the housing.

[0048] (5) The locking member is a screw member or pin member that penetrates the locking hole, The screw member or pin member can contact the porous plate material by protruding from the inner surface of the outer peripheral wall. The static gas bearing according to (1), characterized in that it is a static gas bearing. This configuration allows for the maximum bearing surface area while fixing the porous plate material to the housing. Furthermore, since the screw and pin members are easy to attach and detach, the assembly of the hydrostatic gas bearing is improved, and the porous plate material can be easily replaced when it deteriorates or breaks.

[0049] (6) Porous plate material and A housing on which the porous plate material is stacked, A hydrostatic gas bearing comprising, The porous plate material has a bearing surface and a porous plate material side mating surface which is the opposite side of the bearing surface. The housing has a housing-side mating surface that abuts against the porous plate material-side mating surface, and an outer peripheral wall portion that protrudes in the loading direction from the outer peripheral edge of the housing-side mating surface over its entire circumference and covers the outer peripheral surface of the porous plate material. The outer peripheral wall portion has a groove-shaped housing-side air pocket formed over the entire circumference of the inner surface of the outer peripheral wall portion. The porous plate material has a porous plate material side air pocket formed by recessing a portion of its outer surface, and the position of the housing side air pocket overlaps with that of the housing side air pocket in the loading direction in at least a portion of the way. A hydrostatic gas bearing characterized by the following features. This configuration allows the porous plate material to be fixed to the housing with a simple structure without the need for fixing members, maximizing the bearing surface area. Furthermore, it improves the ease of assembly of the hydrostatic gas bearing and makes it easier to replace the porous plate material when it deteriorates or breaks. [Explanation of Symbols]

[0050] 1. Static gas bearing 2. Intake Cavity 3 recesses 10 Porous board material 11 Bearing surface 12. Joint surface on the porous plate side 13 Large diameter section 14 Small diameter section 15 Porous plate side locking hole 16. Porous plate side air pocket 20 Housing 21 Housing side mating surface 22 Bottom 23 Air supply port 31 Outer wall 32 Locking groove 34 Locking holes 36. Air pocket on the housing side 40, 45 Retaining rings 41,46 Retaining ring end 42 Circumferential center 43 holes 44 openings 48. Bending section 50 Spacer (ring-shaped member) 60 Screw member 61 Base 62 Tip

Claims

1. Porous board material, A housing on which the porous plate material is stacked, A hydrostatic gas bearing comprising, The porous plate material has a bearing surface and a porous plate material side mating surface which is the opposite side of the bearing surface. The housing has a housing-side mating surface that abuts against the porous plate material-side mating surface, and an outer peripheral wall portion that protrudes in the loading direction from the outer peripheral edge of the housing-side mating surface over its entire circumference and covers the outer peripheral surface of the porous plate material. The outer peripheral wall portion has a locking groove formed on the inner peripheral surface of the outer peripheral wall portion so as to extend in the circumferential direction, or a locking hole that penetrates from the inner peripheral surface to the outer peripheral surface of the outer peripheral wall portion. The porous plate material is fixed to the housing by a locking member that engages with the locking groove or the locking hole. A hydrostatic gas bearing characterized by the following features.

2. The outer circumferential surface of the porous plate material has a cylindrical, large-diameter portion connected to the mating surface on the porous plate material side, and a small-diameter portion formed to be smaller in diameter than the large-diameter portion and connected to the bearing surface. The locking member is a retaining ring having a substantially C-shape and fitted into the locking groove, The retaining ring is positioned on the outer circumference of the small-diameter portion of the porous plate material. A hydrostatic gas bearing according to claim 1, characterized in that...

3. The small-diameter portion of the porous plate material is conical in shape, inclined to decrease in diameter as it approaches the bearing surface in the loading direction. The retaining ring is capable of contacting the small diameter portion. A hydrostatic gas bearing as described in claim 2, characterized in that it is a hydrostatic gas bearing as described in claim 2.

4. The retaining ring is provided on the other side in the loading direction and further comprises an annular member that can come into contact with the small diameter portion. A hydrostatic gas bearing as described in claim 2, characterized in that it is a hydrostatic gas bearing as described in claim 2.

5. The locking member is a screw member or pin member that penetrates the locking hole, The screw member or pin member can contact the porous plate material by protruding from the inner surface of the outer peripheral wall. A hydrostatic gas bearing according to claim 1, characterized in that...

6. Porous board material, A housing on which the porous plate material is stacked, A hydrostatic gas bearing comprising, The porous plate material has a bearing surface and a porous plate material side mating surface which is the opposite side of the bearing surface. The housing has a housing-side mating surface that abuts against the porous plate material-side mating surface, and an outer peripheral wall portion that protrudes in the loading direction from the outer peripheral edge of the housing-side mating surface over its entire circumference and covers the outer peripheral surface of the porous plate material. The outer peripheral wall portion has a groove-shaped housing-side air pocket formed over the entire circumference of the inner surface of the outer peripheral wall portion. The porous plate material has a porous plate material side air pocket formed by recessing a portion of its outer surface, and the position of the housing side air pocket overlaps with that of the housing side air pocket in the loading direction in at least a portion of the way. A hydrostatic gas bearing characterized by the following features.

Images