Gasket and joint structure

Abstract

In order to provide a gasket and a joint structure capable of eliminating a dead space between the gasket and a flange, the gasket (30) is annular and is mounted between planar sealing surfaces (12x) of opposing flange sections (12), a step (30d) is formed between a radial inner surface (30b) and a radial outer surface (30c), the radial inner surface (30b) being continuous with an inner peripheral surface (30a), the radial inner surface (30b) being located further outward in the axial direction than the radial outer surface (30c), and the radial outer surface (30c) being located further outward in the axial direction than the radial outer surface (30c). The radial inner side surface (30b) and the radial outer side surface (30c) each have a planar shape orthogonal to the axial direction, and after the radial inner side surface (30b) is in contact with the sealing surface (12x), the radial outer side surface (30c) is in contact with the sealing surface (12x).

Description

Technical Field

[0001] The present invention relates to a gasket and a joint structure using the gasket. Background Art

[0002] As disclosed in Patent Document 1, a conventional pipe joint includes a first joint member and a second joint member having a fluid passage communicating with each other, and a gasket interposed between the abutting end surfaces of the first and second joint members. An annular sealing protrusion is formed on the abutting end surfaces (sealing surfaces) of the first and second joint members. In this pipe joint, the annular sealing protrusion is recessed into the axial end surface of the gasket, thereby improving the seal therebetween.

[0003] However, in a structure where the sealing protrusion formed on the sealing surface compresses the gasket, a dead space may form between the gasket and the sealing surface on the gas contact side of the gasket (radially inward of the sealing protrusion). This dead space causes gas to stagnate within it. Consequently, when a pipe joint with this structure is used in semiconductor manufacturing processes, for example, high-purity source gas may stagnate in the dead space between the gasket and the sealing surface, adversely affecting the concentration control of the high-purity source gas. Prior art literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-17381 Summary of the Invention

[0005] Therefore, the present invention has been made to solve the above-mentioned problems, and a main object of the present invention is to reliably eliminate the dead space between the gasket and the flange portion.

[0006] That is, the gasket of the present invention is characterized in that the gasket is annular and is installed between the planar sealing surfaces of the opposite flange parts, and a step is formed between the axial end surfaces on the radial inner side (hereinafter referred to as the radial inner side surface) and the axial end surfaces on the radial outer side (hereinafter referred to as the radial outer side surface) continuous with the inner circumferential surface, the radial inner side surface is located axially outward than the radial outer side surface, the radial inner side surface and the radial outer side surface are respectively planes orthogonal to the axial direction, and after the radial inner side surface contacts the sealing surface, the radial outer side surface contacts the sealing surface.

[0007] With this configuration, when the flanges are fastened together, the radially inner side of the gasket contacts the sealing surface and plastically deforms, followed by the radially outer side contacting the sealing surface. This results in the highest sealing performance on the gasket's gas contact side (radially inner side), reliably eliminating dead space between the gasket and the flange. Furthermore, since the gas contact side provides the highest sealing performance, any dead space that forms can be detected as a leak. Therefore, the presence of dead space can be detected through leak tests such as helium leak tests.

[0008] In order to allow the deformed portion to escape radially outward rather than radially inward (toward the flow path) when the radially inner surface plastically deforms, it is preferable to form a groove along the circumferential direction between the radially inner surface and the radially outer surface.

[0009] As a specific embodiment of the gasket, preferably, the dimension of the step along the axial direction is 0.03 to 0.09 mm.

[0010] In addition, the joint structure of the present invention is characterized in that the flange parts are fastened to each other in a state where a circular ring-shaped gasket is clamped between the planar sealing surfaces of the opposing flange parts, and the gasket forms steps between the radially inner axial end surfaces (hereinafter referred to as the radially inner side surfaces) and the radially outer axial end surfaces (hereinafter referred to as the radially outer side surfaces) that are continuous with the inner circumferential surface, and the radially inner side surfaces are located axially outward of the radially outer side surfaces, and the radially inner side surfaces and the radially outer side surfaces are respectively planes orthogonal to the axial direction, and after the radially inner side surfaces contact the sealing surface, the radially outer side surfaces contact the sealing surface.

[0011] In order to improve the sealing performance between the gasket and the sealing surface, it is preferable that, in a state where the flange portions are fastened to each other, at least the radially inner surface is plastically deformed so that the radially inner surface and the radially outer surface become flush with each other.

[0012] In order to improve the sealing performance between the gasket and the sealing surface and the number of repeated uses, it is preferred that the sealing surface is mirror-finished.

[0013] According to the present invention described above, the dead space between the gasket and the flange portion can be reliably eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a partial cross-sectional view of a joint structure according to one embodiment of the present invention. Figure 2 This is a diagram showing a state where the clamp joint according to the same embodiment is tightened, as viewed from the axial direction. Figure 3 This is a diagram showing a state in which the clamp joint according to the same embodiment is unfolded, as viewed from the axial direction. Figure 4This is a plan view of the clamp joint according to the same embodiment in an unfolded state. Figure 5 This is a perspective view of the central clamp member of the same embodiment. Figure 6 It is a cross-sectional view and a partially enlarged cross-sectional view schematically showing the structure of the gasket according to the same embodiment. Figure 7 This is a cross-sectional view schematically showing a sealing mechanism of a joint structure using the gasket of the same embodiment. Figure 8 It is a cross-sectional view of a joint structure according to a modified embodiment. DETAILED DESCRIPTION

[0015] <One embodiment of the present invention> An embodiment of the joint structure of the present invention is described below with reference to the accompanying drawings. In addition, for ease of understanding, any of the following figures are schematically depicted with appropriate omissions or exaggerations. Identical components are denoted by the same reference numerals, and descriptions thereof are omitted as appropriate.

[0016] like Figure 1 As shown, the joint structure 100 of this embodiment is a joint structure that connects a pair of pipe members 10 via a clamp joint 20. Specifically, the joint structure 100 includes: the clamp joint 20 for connecting the pair of pipe members 10 in an opposed state; and an annular gasket 30 interposed between the pair of pipe members 10, thereby connecting the pair of pipe members 10 in an airtight manner.

[0017] The pipe component 10 includes a pipe body 11 having a linear flow path formed therein, and a flange portion 12 provided at the end of the pipe body 11. A planar sealing surface 12x is formed on the front end surface of the flange portion 12, which is in close contact with the gasket 30. This sealing surface 12x is a plane orthogonal to the axial direction. The sealing surface 12x is mirror-finished. Furthermore, an inclined surface 14 is formed on the back surface of the flange portion 12, opposite to the opposing surface (front end surface), and the diameter thereof increases toward the front end. Furthermore, a step portion 15 is formed on the outer peripheral surface of the flange portion 12, which is formed to reduce the diameter. A support frame 50 for retaining the gasket 30 is mounted on the step portion 15. Furthermore, an annular dust-proofing guard 60 may be mounted on the outer periphery of the step portion 15 as needed.

[0018] The clamping joint 20 is externally fitted to the flange portions 12 in the opposite state and tightens them together. Figures 1 to 4 As shown, the clamp joint 20 includes a clamp body 21 having a groove 211 provided on its inner peripheral surface so as to extend in the circumferential direction, and a tightening mechanism 22 for tightening the clamp body 21 so as to reduce its inner diameter.

[0019] The clamp body 21 comprises a series of clamping members 21a through 21c, with adjacent clamping members rotatably connected to one another. Specifically, the clamp body 21 includes a central clamping member 21a and a pair of outer clamping members 21b and 21c rotatably connected to the ends of the clamping member 21a. Each clamping member 21a through 21c is made of stainless steel, such as SUS630 or SUS316.

[0020] Especially if Figure 1 as well as Figure 4 As shown, a groove 211 is formed on the inner circumferential surface of each clamping member 21a-21c, extending in the circumferential direction. The groove 211 has a width sufficient to fit over the outer circumferential edge of the pair of opposing flanges 12. The inner surfaces of the pair of sidewalls 212 forming the grooves 211 are formed with inclined surfaces 213 corresponding to the inclined surfaces 14 of the flanges 12. Furthermore, the grooves 211 of each clamping member 21a-21c have a depth sufficient to prevent the bottom surface of the groove 211 from contacting the outer circumferential surface of the flanges 12 when the inclined surfaces 213 of the sidewalls 212 are in contact with the inclined surfaces 14 of the flanges 12.

[0021] These clamping members 21a to 21c are rotatably connected by a hinge pin 214. The hinge pin 214 is made of stainless steel such as SUS630, SUS316, or SUS304, and is preferably made of a material having strength equal to or greater than that of the materials of the clamping members 21a to 21c.

[0022] like Figure 4 As shown, a first connection portion 215 having a through hole H1 through which a hinge pin 214 is inserted is formed at one end portion of each of the pair of outer clamp members 21b and 21c connected to the central clamp member 21a.

[0023] The first connecting portion 215 is formed by a convex portion protruding toward the central clamping member 21a at one end of the outer clamping members 21b and 21c. The width (axial dimension) of the convex portion is smaller than the distance between the pair of side walls 212 forming the groove 211 (the width of the bottom surface of the groove 211) (see Figure 4 ).

[0024] Furthermore, a pair of second connecting portions 216 are formed at both ends of the central clamping member 21a. These second connecting portions 216 sandwich the first connecting portions 215 of the outer clamping members 21b and 21c and have fixing holes H2 for fixing the hinge pin 214. The hinge pin 214 is fixed to the fixing holes H2 by riveting, press-fitting, or the like.

[0025] The pair of second connecting parts 216 sandwich the convex part of the first connecting part 215 from both sides in the axial direction with a small gap therebetween. A recessed part is formed at each end of the central clamping member 21a, into which the convex part of the first connecting part 215 fits with a small gap therebetween. The axial wall portion forming the recessed part serves as the second connecting part 216. In addition, the pair of second connecting parts 216 are located on the extension line of the pair of side wall portions 212 forming the groove 211 in the circumferential direction (refer to FIG. Figure 4 ).

[0026] Moreover, if Figures 2 to 5 As shown, the upper surface portions 212a of the pair of side walls 212 provided on the central clamping member 21a are formed circumferentially from the pair of second connecting portions 216 at one end to the pair of second connecting portions 216 at the other end. Specifically, the side walls 212 are formed so that the upper surface portions 212a of the side walls 212 are connected to both the second connecting portions 216 at one end and the second connecting portions 216 at the other end. In this embodiment, when viewed from the axial direction, the upper surface portions 216a of the second connecting portions 216 are linearly continuous with the upper surface portions 212a of the side walls 212. Furthermore, inclined surfaces 213 corresponding to the inclined surfaces 14 of the flange portion 12 are formed throughout the inner surfaces of the pair of side walls 212 of the central clamping member 21a.

[0027] Furthermore, the difference between the central clamping member 21a and the outer clamping members 21b and 21c is the shape of the side wall portion 212 of the central clamping member 21a to prevent interference with the side wall portions of the outer clamping members 21b and 21c. In this embodiment, the gap formed between the side wall portion 212 of the central clamping member 21a and the side wall portions of the outer clamping members 21b and 21c is not formed to extend from the hinge pin 214 toward the axis center, but is formed along a direction perpendicular to the radial direction from the axis center (at Figure 2 The center is the left-right direction, and the arrangement direction of the two hinge pins 214 extends.

[0028] The fastening mechanism 22 fastens the free ends of the pair of outer clamping members 21b, 21c to each other. Figures 1 to 4 As shown, the fastening mechanism 22 comprises a screw member 221 rotatably disposed in a through-hole H3 formed at the free end of one outer clamping member 21b; and a female threaded hole 222 formed at the free end of the other outer clamping member 21c. By screwing the screw member 221 into the female threaded hole 222, the pair of outer clamping members 21b and 21c can be connected, and the inner diameter of the clamping body 21 can be expanded or reduced. The screw member 221 is made of stainless steel, such as SUS304 or SUS316.

[0029] Especially if Figure 4 As shown, the through hole H3 formed at the free end of one outer clamping member 21b is an elongated circular shape extending radially. This elongated through hole H3 absorbs any tilting of the screw member 221 relative to the outer clamping member 21b when the screw member 221 is screwed into the female threaded hole 222. Furthermore, a stop ring 223 prevents the screw member 221 from disengaging from the through hole H3.

[0030] In addition, the stop ring 223 is configured so as not to contact the other outer clamping member 21c when the free ends of the pair of outer clamping members 21b and 21c are fastened to each other (see FIG. Figure 2 Specifically, when the free ends of the pair of outer clamping members 21b and 21c are fastened together, the thickness of the stop ring 223 is smaller than the gap formed between these free ends. This configuration ensures sufficient tightening margin for the screw member 221, enabling torque management of the screw member 221.

[0031] The gasket 30 is mounted between the planar sealing surfaces 12x of the opposing flange portions 12. The gasket 30 is annular and has an inner diameter that is the same as or slightly larger than the inner diameter of the flow path of the pair of pipe members 10. The gasket 30 is made of high-cleanliness stainless steel such as SUS316 or SUS316L.

[0032] Specifically, if Figure 6 As shown, the gasket 30 has radially inner end surfaces (hereinafter referred to as radially inner side surfaces 30b) continuous with the inner peripheral surface 30a, radially outer end surfaces (hereinafter referred to as radially outer side surfaces 30c), and steps 30d formed therebetween.

[0033] The radially inner side surface 30b is annular and flat, perpendicular to the axial direction. Furthermore, the radially outer side surface 30c is annular and larger than the radially inner side surface 30b, forming a flat surface perpendicular to the axial direction. Furthermore, the radially inner side surface 30b is located axially outward relative to the radially outer side surface 30c. In other words, the radially inner side surface 30b protrudes axially outward relative to the radially outer side surface 30c. In this embodiment, the radially inner side surface 30b protrudes axially outward relative to the radially outer side surface 30c by 0.03 to 0.09 mm.

[0034] Furthermore, the step 30d is annular and formed between the radially inner side surface 30b and the radially outer side surface 30c. The dimension of the step 30d along the axial direction is 0.03 to 0.09 mm. In this embodiment, the step 30d, that is, the step 30d between the radially inner side surface 30b and the radially outer side surface 30c, has an annular groove 30M formed along the circumferential direction. This groove 30M can absorb the plastic deformation of the radially inner side surface 30b. The cross-sectional shape of the groove 30M along the axial direction is not limited to a circular arc and can also be a V-shape or a rectangle.

[0035] Next, refer to Figure 7 A method of connecting a pair of pipe members 10 using the clamp joint 20 and a sealing mechanism of the joint structure using the gasket 30 according to the present embodiment will be described.

[0036] The flanges 12 of the pair of pipe members 10 are positioned opposite to each other with the gasket 30 interposed therebetween. Figure 7 As shown in (a) of FIG. 1 , the support frame 50 holding the gasket 30 is attached to the step 15 formed on the flange 12 of one pipe member 10 . Furthermore, the gasket 30 is sandwiched between the flange 12 of the other pipe member 10 .

[0037] In this state, the clamping body 21 is installed so as to surround the pair of flanges 12. At this point, the grooves 211 of each clamping member 21a-21c fit over the outer peripheral edges of the pair of flanges 12. Furthermore, by screwing the screw member 221 into the female threaded hole 222, the free ends of the pair of outer clamping members 21b and 21c are fastened to each other. This reduces the inner diameter of the clamping body 21, and the inclined surfaces 213 of each clamping member 21a-21c press against the inclined surfaces 14 of the flanges 12. The resulting axial force component presses the flanges 12 together.

[0038] If the flange portions 12 are press-bonded to each other, Figure 7 As shown in (b), first, the sealing surface 12x of the flange portion 12 is brought into surface contact with the radially inner side surface 30b of the gasket 30. Thereafter, as the flange portions 12 are press-fitted together, Figure 7 As shown in (c), the radially inner surface 30b plastically deforms while maintaining surface contact with the sealing surface 12x. The deformed portion of the flange 12 enters the groove 30M formed in the step 30d. Furthermore, the sealing surface 12x of the flange 12 is in surface contact not only with the radially inner surface 30b of the gasket 30 but also with the radially outer surface 30c of the gasket 30. As a result, when the flanges 12 are fastened together, the radially inner surface 30b and the radially outer surface 30c are flush with each other.

[0039] In this way, by the tightening of the tightening mechanism 22, the radial inner side surface 30b is plastically deformed until it becomes flush with the radial outer side surface 30c, and the gasket 30 is in close contact with substantially the entire surface of the sealing surface 12x. The surface pressure of the radial inner side surface 30b after plastic deformation is greater than that of the radial outer side surface 30c, and the sealing portion (between the radial inner side surface 30b and the sealing surface 12x) is completely sealed without a gap. In addition, the inner peripheral surface 30a of the gasket 30 and the inner peripheral surface formed by the flow path of each pipe component 10 become substantially flush with each other. In the joint structure 100 of this embodiment, by the tightening of the tightening mechanism 22, the surface pressure σ of the radial inner side surface 30b is σ = 350N / mm 2 , so that the surface pressure σ of the radially outer side surface 30c is σ=250N / mm 2 , by making the surface pressure σ>180N / mm required for metal plane sealing 2 (JIS standard) to ensure sealing.

[0040] <Effects of this embodiment> With the clamping joint 20 of this embodiment configured in this manner, when the flange 12 is tightened, the radially inner side surface 30b comes into surface contact with the sealing surface 12x and undergoes plastic deformation, followed by the radially outer side surface 30c coming into contact with the sealing surface 12x. Therefore, when the flanges 12 are tightened, the gas-contacting side (radially inner side) of the gasket 30 provides the highest sealing performance, reliably eliminating dead space between the gasket 30 and the flange's sealing surface 12x. Furthermore, since the gas-contacting side provides the highest sealing performance, leaks can be detected even if dead space is present. Therefore, the presence of dead space can be detected through leak tests such as helium leak tests.

[0041] Furthermore, in this embodiment, the upper surface portions 212a of the pair of sidewall portions 212 provided on the central clamping member 21a are formed circumferentially from the pair of second connecting portions 216 at one end to the pair of second connecting portions 216 at the other end. This improves the mechanical strength of the central clamping member 21a of the clamping joint 20. As a result, the overall mechanical strength of the clamping joint 20 is enhanced, and even when tightened to the point where the radially inner side surface 30b plastically deforms, the clamping joint 20 is prevented from being damaged. Furthermore, by securing the hinge pin 214 to the fixing hole of the central clamping member 21a through caulking, press-fitting, or the like, the mechanical strength of the central clamping member 21a is further enhanced. Consequently, the safety of the clamping joint 20 is further enhanced.

[0042] <Other Embodiments> In addition, the present invention is not limited to the above-described embodiment.

[0043] For example, in the above embodiment, the inclined surface 213 is formed entirely on the inner surface of the side wall portion 212 of the central clamp member 21a. However, the inclined surface 213 may be formed only partially on the inner surface of the side wall portion 212 of the central clamp member 21a.

[0044] In addition, in the embodiment, when viewed from the axial direction, the upper surface portion 216a of the second connecting portion 216 and the upper surface portion 212a of the side wall portion 212 are continuous in a straight line, but as long as the upper surface portion 212a of the side wall portion 212 is continuous with the second connecting portion 216, their upper surface portions 212a, 216a may not be continuous in a straight line.

[0045] In addition, in addition to being a structure in which the screw component 221 is threadedly engaged with the female threaded hole 222 formed in the outer clamping component 21c, the fastening mechanism 22 can also be a structure in which a through hole for inserting the screw component 221 is formed at the free end of the other side's outer clamping component 21c and the nut component is threadedly engaged with the screw component 221 extending from the through hole.

[0046] The gasket 30 in the above embodiment has a structure in which the step 30d has the groove 30M, but may also have a structure in which the step 30d does not have the groove 30M.

[0047] The connection structure 100 of the embodiment is a structure in which the flange parts 12 are fastened to each other by the clamping joint 20, but Figure 8 As shown, the following structure can also be adopted: the pipe joint includes: a first nut component 71, which is embedded in the outer periphery of one pipe component 10 and has a male thread portion formed on the outer peripheral surface; and a second nut component 72, which is embedded in the outer periphery of the other pipe component 10 and has a female thread portion formed on the inner periphery to be screwed together with the male thread portion. The pair of pipe components 10 are connected by screwing the male thread portion of the first nut component 71 and the female thread portion of the second nut component 72.

[0048] To explain more specifically, the front end portion 711 of the first nut component 71 pushes the flange 12 of one pipe component 10 from the back side. Furthermore, the second nut component 72 is provided with a receiving recess 721 for receiving the flanges 12 of each of the pair of pipe components 10. The flange 12 of the other pipe component 10 is received from the back side through the bottom surface of the receiving recess 721. With this structure, the male thread portion of the first nut component 71 and the female thread portion of the second nut component 72 are screwed together, so that the first nut component 71 pushes the flange 12 of one pipe component 10 from the back side, and the second nut component 72 receives the flange 12 of the other pipe component 10 from the back side. As in the above embodiment, the sealing surface 12x contacts the gasket 30, thereby airtightly connecting the pair of pipe components 10.

[0049] In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Description of Reference Numerals

[0050] 100 joint structure 12 Flange 12x sealing surfaces 30 gasket 30a inner circumference 30b radial inner side 30c radial outer surface 30d steps 30M slot.

Claims

1. A gasket, characterized in that: The gasket is annular and installed between the planar sealing surfaces of the opposite flange parts. A step is formed between the radially inner side surface and the radially outer side surface, wherein the radially inner side surface is the axial end surfaces of the radially inner side continuous with the inner peripheral surface, and the radially outer side surface is the axial end surfaces of the radially outer side. The radially inner side surface is located axially outward of the radially outer side surface, The radially inner side surface and the radially outer side surface are respectively in the shape of planes perpendicular to the axial direction, After the radially inner side surface contacts the sealing surface, the radially outer side surface contacts the sealing surface.

2. The gasket according to claim 1, characterized in that A groove is formed along the circumferential direction between the radially inner side surface and the radially outer side surface.

3. The gasket according to claim 1 or 2, characterized in that The dimension of the step along the axial direction is 0.03 to 0.09 mm.

4. A joint structure, characterized in that: The flanges are fastened to each other with an annular gasket sandwiched between the planar sealing surfaces of the opposing flanges. The gasket has a step formed between a radially inner side surface and a radially outer side surface, wherein the radially inner side surface is the radially inner axial end surface continuous with the inner peripheral surface, and the radially outer side surface is the radially outer axial end surface. The radially inner side surface is located axially outward of the radially outer side surface, The radially inner side surface and the radially outer side surface are respectively in the shape of planes perpendicular to the axial direction, After the radially inner side surface contacts the sealing surface, the radially outer side surface contacts the sealing surface.

5. The joint structure according to claim 4, characterized in that: In a state where the flange portions are fastened to each other, at least the radially inner surface is plastically deformed, and the radially inner surface and the radially outer surface become flush with each other.

6. The joint structure according to claim 4 or 5, characterized in that: The sealing surface is mirror-finished.

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