Stub ends and connection structures

Abstract

To provide a stub end capable of suppressing appearance of gaps where particles reside.SOLUTION: A flare part 23 of a stub end 11 has: an opening 24b of a flow channel 24; and a contact surface 23a contacting a packing 13 arranged around the opening 24b and is arranged between itself and a connection target. The contact surface 23a is inclined toward a terminal 21a side as it goes away from a central axis O of the flow channel 24. On a straight line L1 which passes an edge 23b of the opening 24b and is vertical to the central axis O of the flow channel 24, when a point moving from the edge 23b of the opening 24b to the outside of the contact surface 23a is a position P1, an intersection which passes the position P1 and crosses the contact surface 23a of a straight line L2 parallel to the central axis O is a position P2, length from the edge 23b of the opening 24b to the position P1 on the straight line L1 is d, and length from the position P1 to the position P2 on the straight line L2 is h, 0.5≤(h / d)×100≤18 is satisfied.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to stub ends and connection structures. [Background technology]

[0002] BACKGROUND ART In factory piping and the like, the end of a pipe is connected to the end of another pipe by a pipe joint structure (see, for example, Patent Document 1).

[0003] The pipe joint structure shown in Patent Document 1 comprises a packing, stub ends arranged on both sides of the packing, and loose flanges provided on the outer periphery of each stub end, and the loose flanges are fastened with bolts. This fastening causes the stub ends to compress the ribs of the packing, causing the ribs to collapse and maintaining sealing performance.

[0004] Fig. 11 is a schematic diagram showing a state in which a packing 1003 is compressed by a pair of stub ends 1001, 1002 in a conventional pipe fitting structure. Fig. 11 shows a flow path 1004 through which a liquid flows. The packing 1003 has protrusions 1005 formed on both sides of the stub ends 1001, 1002. The protrusions 1005 are compressed by the contact surfaces 1006 of the stub ends 1001, 1002, ensuring the sealing of the flow path 1004. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-162147 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the configuration shown in Patent Document 1, the contact surface 1006 is formed perpendicular to the central axis O of the flow path 1004, which can result in insufficient flattening of the convex portion 1005 of the packing 1003. When the convex portion 1005 is not flattened sufficiently, a minute gap occurs between the packing 1003 and the stub ends 1001 and 1002. FIG. 11 shows the gap S that occurs on the flow path 1004 side of the convex portion 1005 (see the area surrounded by the dotted line). The gap causes particles (fine particles) to accumulate, resulting in the release of particles after water passes through the piping. This has a particularly significant effect in the field of semiconductor manufacturing when ultrapure water is passed through, resulting in a decrease in the yield of semiconductor products.

[0007] An object of the present disclosure is to provide a stub end and a connection structure that can suppress the occurrence of gaps in which particles can accumulate. [Means for solving the problem]

[0008] To achieve the above object, a stub end according to a first aspect is used for connecting pipes and is made of a resin material. The stub end includes a flow path, a first end, and a second end. A liquid flows through the flow path. The first end has a first opening of the flow path and a contact surface that is disposed around the first opening and contacts a seal member disposed between the stub end and a connection target. The second end has a second opening of the flow path facing the first opening. The contact surface is inclined toward the second end as it moves away from the central axis of the flow path. A first position is defined as a point on a first line that passes through the edge of the opening and is perpendicular to the central axis of the flow path, moving from the edge of the opening toward the outside of the contact surface. A second position is defined as an intersection of a second line that passes through the first position and is parallel to the central axis and intersects with the contact surface. The length on the first line from the edge of the opening to the first position is defined as d, and the length on the second line from the first position to the second position is defined as h, where 0.5≦(h / d)×100≦18 is satisfied.

[0009] In this way, the inclination of the contact surface of the stub end increases the crushing of the convex portion of the seal member, thereby reducing the gap between the seal member and the stub end and suppressing particle retention.In the field of semiconductor manufacturing, this also improves the yield of semiconductor products.

[0010] The stub end according to the second aspect is the stub end according to the first aspect, wherein the resin material is polyethylene.

[0011] By using polyethylene as the material for the stub end in this way, the stub end and the pipe can be joined by heat fusion, etc. Furthermore, since it can be easily cut on site, it is easy to adjust the length, etc.

[0012] A stub end according to a third aspect is the stub end according to the first or second aspect, wherein the resin material is high-density polyethylene.

[0013] In this way, by using high density polyethylene as the material for the stub end, rigidity and strength can be ensured, and therefore the collapse of the convex portion of the sealing member can be further increased.

[0014] A connecting structure according to a fourth aspect includes a first stub end according to any one of the first to third aspects, a second stub end according to any one of the first to third aspects, a seal member, a first flange, a second flange, and a fastening portion. The seal member is disposed between a contact surface of the first stub end and a contact surface of the second stub end. The first flange is disposed around the first stub end. The second flange is disposed around the second stub end. The fastening portion fastens the first flange and the second flange. The seal member has a flat portion, a first annular convex portion, and a second annular convex portion. The first convex portion is formed on a first surface of the flat portion facing the first stub end. The second convex portion is formed on a second surface of the flat portion facing the second stub end. The first convex portion is compressed by the contact surface of the first stub end, and the second convex portion is compressed by the contact surface of the second stub end.

[0015] In this way, the inclination of the contact surface of the stub end increases the crushing of the rib of the seal member, thereby reducing the gap between the seal member and the stub end and suppressing particle retention.In the field of semiconductor manufacturing, this also improves the yield of semiconductor products. [Effects of the Invention]

[0016] According to the present disclosure, it is possible to provide a stub end and a connection structure that can suppress the occurrence of gaps in which particles can accumulate. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view showing a state in which a first pipe and a second pipe are connected to the connection structure of the present embodiment. FIG. [Figure 2] 1 is a perspective view showing a state before a first pipe and a second pipe are connected to the connection structure of the present embodiment. FIG. [Figure 3] FIG. 2 is a cross-sectional view of the connection structure of the present embodiment. [Figure 4] 1A is a front cross-sectional view of a stub end of the present embodiment, and FIG. 1B is a plan view of the stub end of the present embodiment. [Figure 5] FIG. 10 is a schematic cross-sectional view of a stub end for explaining the inclination of the contact surface. [Figure 6] 6(a) is a plan view of the packing of the present embodiment, (b) is a cross-sectional view taken along the line AA in FIG. 6(a), and (c) is an enlarged view of part B in FIG. 6(b). [Figure 7] 7(a) is a front view of the flange of this embodiment, (b) is a cross-sectional view taken along the line CC in FIG. 7(a), and (c) is a cross-sectional view taken along the line DD in FIG. 7(a). [Figure 8] 10 is a schematic cross-sectional view showing a state in which a packing is compressed by a pair of stub ends in the connection structure of the present embodiment. FIG. [Figure 9] 10 is a cross-sectional view showing a state in which a through hole for a water leakage test is formed in the contact structure of the present embodiment. FIG. [Figure 10] FIG. 2 is a diagram showing a water leakage tester according to the present embodiment. [Figure 11] FIG. 10 is a cross-sectional schematic view showing a state in which a packing is compressed by a pair of stub ends in a conventional pipe joint structure. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0019] <Configuration> (Overview of connection structure 3) Fig. 1 is a perspective view showing a connection structure 3 in which a first pipe 1 and a second pipe 2 are connected. Fig. 2 is a perspective view showing a state before the first pipe 1 and the second pipe 2 are attached to the connection structure 3.

[0020] End 1a of first pipe 1 shown in Figure 2 is joined by heat fusion to end 21a of stub end 11 (described later) of connection structure 3. This heat fusion joint 4 is shown in Figure 1. End 2a of second pipe 2 shown in Figure 2 is joined by heat fusion to end 21a of stub end 12 (described later) of connection structure 3. This heat fusion joint 5 is shown in Figure 1. Note that in Figure 1, the stub end 11 and first pipe 1, and the stub end 12 and second pipe 2 are connected by butt fusion, but they may also be connected via electrofusion joints.

[0021] The first pipe 1 and the second pipe 2 are made of a resin material. A thermoplastic resin is used as the resin material. Specifically, the first pipe 1 and the second pipe 2 are made of a polyolefin such as polyethylene.

[0022] As shown in Figure 2, first pipe 1 and second pipe 2 have flow paths 1b and 2b extending therethrough, each having a circular cross section. Connection structure 3 has flow path 3a extending therethrough, each having a circular cross section. When first pipe 1 and second pipe 2 are connected to connection structure 3, the axes of the flow paths of first pipe 1, second pipe 2, and connection structure 3 are arranged on the same axis O. In connection structure 3, first pipe 1, and second pipe 2, the direction perpendicular to each axis and moving toward or away from each other is defined as the radial direction, and the direction rotating around each axis is defined as the circumferential direction.

[0023] Fig. 3 is a diagram showing a cross-sectional configuration of the connection structure 3. The connection structure 3 has a stub end 11 (an example of a first stub end), a stub end 12 (an example of a second stub end), a packing 13 (an example of a sealing member), a flange 14 (an example of a first flange), and a flange 15 (an example of a second flange). Note that Fig. 3 shows a state in which the packing 13 is not compressed by the stub ends 11 and 12 in order to show the positional relationship of each component.

[0024] Stub end 11 and stub end 12 (an example of a connection object) are arranged opposite each other with packing 13 sandwiched between them. Flange 14 is arranged around stub end 11. Flange 15 is arranged around stub end 12. Flanges 14 and 15 are fastened together by a plurality of bolts 16 and nuts 17. In FIG. 3, bolts 16 and nuts 17 are indicated by two-dot chain lines, showing the configuration on the far side of the page. Bolts 16 and nuts 17 correspond to an example of a fastening part.

[0025] (stub end) The stub ends 11, 12 are made of a resin material. Polyethylene can be used as the resin material. It is more preferable to use high-density polyethylene as the resin material. High-density polyethylene is defined by JIS K 6922-1 and has a density of 0.942 kg / m 3 It is defined as polyethylene having the above properties.

[0026] Since the shapes of the stub end 11 and the stub end 12 are the same, the following description will be given taking the stub end 11 as an example. Fig. 4(a) is a front cross-sectional view of the stub end 11. Fig. 4(a) is a cross-sectional view of the stub end 11 including the axis O. Fig. 4(b) is a plan view of the stub end 11.

[0027] The stub end 11 has a connection portion 21 , an intermediate portion 22 , a flared portion 23 , and a flow passage 24 .

[0028] The connecting portion 21 is joined to the end 1a of the first tube 1 by butt welding or fusion via an electrofusion joint. The flared portion 23 presses against the packing 13. The intermediate portion 22 is disposed between the connecting portion 21 and the flared portion 23 (an example of a first end portion) in the axial direction O. The outer diameters of the connecting portion 21, the intermediate portion 22, and the flared portion 23 increase in this order. The flow path 24 is formed from the connecting portion 21 to the flared portion 23.

[0029] The connecting portion 21 is cylindrical. The connecting portion 21 has an end portion 21a (an example of a second end portion) in which an opening 24a (an example of a second opening) of the flow path 24 is formed. The end portion 21a of the connecting portion 21 is joined to the end 1a of the first tube 1 by thermal fusion.

[0030] The intermediate portion 22 is cylindrical. The intermediate portion 22 is disposed on the opposite side of the end portion 21a of the connecting portion 21. The intermediate portion 22 is formed to have a larger outer diameter than the connecting portion 21. The intermediate portion 22 is formed to have the same inner diameter as the connecting portion 21.

[0031] Flare portion 23 is cylindrical. Flare portion 23 is disposed on the opposite side of intermediate portion 22 from connecting portion 21. Flare portion 23 is formed to have a larger outer diameter than intermediate portion 22. The inner diameter of flare portion 23 is formed to be the same size as intermediate portion 22.

[0032] Flare portion 23 has end face 23e arranged on the packing 13 side. End face 23e of flare portion 23 has opening 24b (an example of a first opening) of flow path 24 and contact surface 23a. Opening 24b is formed in the center of end face 23e of flare portion 23. Opening 24b is arranged opposite opening 24a. Flow path 24 is formed linearly along axis O. Contact surface 23a is formed on end face 23e of flare portion 23. Contact surface 23a is arranged around opening 24b and comes into contact with packing 13.

[0033] Contact surface 23a is an inclined surface inclined with respect to a plane perpendicular to axis O. Fig. 5 is a schematic cross-sectional view of stub end 11 for explaining the inclination of contact surface 23a. Fig. 5 is a cross-sectional view including axis O. For ease of understanding, the shape of stub end 11 in Fig. 5 is different from that in Fig. 4.

[0034] Contact surface 23a is inclined toward end portion 21a as it moves outward from central axis O of flow path 24. The edge of opening 24b is designated as 23b, and the radially outer edge of contact surface 23a is designated as outer edge 23c. In this embodiment, outer edge 23c of contact surface 23a is located closer to end portion 21a than edge 23b of opening 24b.

[0035] A line L1 (an example of a first line) passes through position P0 on edge 23b of opening 24b and is perpendicular to central axis O of flow path 24. A point on line L1 that is moved an arbitrary distance radially outward from edge 23b of opening 24b is defined as position P1 (an example of a first position). A line L2 (an example of a second line) passes through position P1 and is parallel to central axis O. The intersection of line L2 and contact surface 23a is defined as position P2 (an example of a second position). Then, the length from position P0 to position P1 on line L1 is defined as d, and the length from position P1 to position P2 on line L2 is defined as h. d and h are set to satisfy the following equation (1).

[0036] 0.5(%)≦(h / d)×100≦18(%)···(1) The gradient of the contact surface 23a can be defined as (h / d)×100(%) as described above, and is set to 0.5% or more and 18% or less.

[0037] In this embodiment, the entire end face 23e from the edge 23b of the opening 24b to the outer edge 23c is inclined as the contact surface 23a, so if the length d when position P2 is the position of the outer edge 23c is d1 and the length h is h1, then 0.5(%)≦(h1 / d1)×100≦18(%) is satisfied.

[0038] In this embodiment, the stub end 12 has the same shape as the stub end 11, and as shown in Fig. 3, has a connection portion 21, an intermediate portion 22, a flared portion 23, and a flow path 24. As shown in Fig. 3, the stub end 11 and the stub end 12 are arranged so that their contact surfaces 23a face each other.

[0039] (rubber seal) 3, the packing 13 is disposed between the contact surface 23a of the stub end 11 and the contact surface 23a of the stub end 12. The packing 13 is preferably made of ethylene propylene diene (EPDM) rubber. A portion of the packing 13 is coated with polytetrafluoroethylene (PTFE).

[0040] Packing 13 is formed in the shape of an annular plate. The outer diameter of packing 13 is approximately the same as that of flanges 14 and 15. The inner diameter of central hole 30 of packing 13 is approximately the same as that of flow passages 24 of stub ends 11 and 12. The center of central hole 30 of packing 13 is positioned on axis O.

[0041] Fig. 6(a) is a plan view of the packing 13. Fig. 6(b) is a cross-sectional view of the packing 13 taken along line AA in Fig. 6(a). Fig. 6(c) is an enlarged view of part B in Fig. 6(b).

[0042] As shown in Figures 6(a) and 6(b), the gasket 13 has a flat portion 31, an inner convex portion 32 (an example of a first convex portion), an outer convex portion 33, an inner convex portion 34 (an example of a second convex portion), and an outer convex portion 35.

[0043] The flat portion 31 has a main surface 31a (an example of a first surface) on the stub end 11 side and a main surface 31b (an example of a second surface) on the stub end 12 side.

[0044] As shown in FIG. 6(b), the inner convex portion 32 and the outer convex portion 33 are disposed on the main surface 31a. The inner convex portion 32 and the outer convex portion 33 protrude from the main surface 31a along the axis O. The inner convex portion 32 is formed in an annular shape to surround the central hole 30 and is formed concentrically with the central hole 30. The outer convex portion 33 is formed in an annular shape to surround the inner convex portion 32 and is formed concentrically with the central hole 30. The diameter of the inner convex portion 32 is larger than the diameter of the opening 24b of the contact surface 23a of the stub end 11. The diameter of the outer convex portion 33 is smaller than the diameter of the contact surface 23a of the stub end 11. As a result, the inner convex portion 32 and the outer convex portion 33 come into contact with the contact surface 23a of the stub end 11.

[0045] As shown in FIG. 6( b), the inner convex portion 34 and the outer convex portion 35 are disposed on the main surface 31b. The inner convex portion 34 and the outer convex portion 35 protrude from the main surface 31b along the axis O. The inner convex portion 34 is formed in an annular shape to surround the central hole 30 and is formed concentrically with the central hole 30. The outer convex portion 35 is formed in an annular shape to surround the inner convex portion 34 and is formed concentrically with the central hole 30. The diameter of the inner convex portion 34 is larger than the diameter of the opening 24b of the contact surface 23a of the stub end 12. The diameter of the outer convex portion 35 is smaller than the diameter of the contact surface 23a of the stub end 12. As a result, the inner convex portion 34 and the outer convex portion 35 come into contact with the contact surface 23a of the stub end 12.

[0046] The inner convex portion 34 is formed at the same position as the inner convex portion 32 in the radial direction and has the same shape as the inner convex portion 32. The outer convex portion 35 is formed at the same position as the outer convex portion 33 in the radial direction and has the same shape as the outer convex portion 33.

[0047] As shown in FIG. 6(a), the packing 13 has an inner circumferential portion 36 and an outer circumferential portion 37. The inner circumferential portion 36 is a portion of the packing 13 extending radially outward from the edge 13e of the central hole 30. The inner circumferential portion 36 also includes the outer convex portion 33 and the outer convex portion 35. As shown in FIG. 6(c), the inner circumferential portion 36 has a coating portion 36a on its surface that is coated with PTFE. The outer circumferential portion 37 is a portion of the packing 13 that is radially outward from the inner circumferential portion 36.

[0048] Four bolt holes 38 are formed in the circumferential direction around the center on the outer periphery 37 of the packing 13. The bolt holes 38 are arranged radially outward from the outer protrusions 33 and 35.

[0049] (flange) As shown in Fig. 3, the flange 14 is disposed radially outward of the stub end 11 and is rotatable relative to the stub end 11. The flange 14 is a loose flange. The flange 15 is disposed radially outward of the stub end 12 and is rotatable relative to the stub end 12. The flange 15 is a loose flange.

[0050] The flanges 14 and 15 are made of a resin material, and it is more preferable that the flanges 14 and 15 are made of glass fiber reinforced polypropylene (GFPP).

[0051] Since flange 14 and flange 15 have the same configuration, flange 14 will be described as an example. Fig. 7(a) is a front view of flange 14. Fig. 7(b) is a cross-sectional view taken along the line CC in Fig. 7(a). Fig. 7(c) is a cross-sectional view taken along the line DD in Fig. 7(a).

[0052] The flange 14 is formed in a disk shape with a diameter larger than that of the flare portion 23 of the stub end 11 .

[0053] The flange 14 has an insertion hole 41 into which the stub end 11 is inserted, and a plurality of bolt holes 42 arranged around the insertion hole 41. The insertion hole 41 and the bolt holes 42 are formed from a surface 43 of the flange 14 facing the packing 13 to a surface 44 opposite the packing 13. In this embodiment, four bolt holes 42 are formed.

[0054] The insertion hole 41 has a large diameter portion 45 and a small diameter portion 46 with different inner diameters. The large diameter portion 45 is formed along the axis O from the surface 43 of the flange 14. The flared portion 23 of the stub end 11 is disposed in the large diameter portion 45. The small diameter portion 46 is disposed on the surface 44 side of the large diameter portion 45. The small diameter portion 46 is formed from the large diameter portion 45 to the surface 44. The intermediate portion 22 of the stub end 11 is disposed in the small diameter portion 46. The contact surface 23a of the stub end 11 protrudes slightly toward the packing 13 beyond the surface 43 of the flange 14. In this embodiment, the edge 23b of the opening 24b of the stub end 11 protrudes slightly toward the packing 13 beyond the surface 43 of the flange 14, and the outer edge 23c of the stub end 11 protrudes slightly toward the packing 13 beyond the surface 43 of the flange 14. The positional relationship between the contact surface 23a of the stub end 12 and the surface 43 of the flange 14 is also similar.

[0055] The flange 14 has a plurality of ribs 48 formed on the surface 44 and a plurality of recesses 47 formed on the surface 44. The ribs 48 are arranged between the bolt holes 42 in the circumferential direction. The ribs 48 are arranged along the diameter direction. The ribs 48 are provided for reinforcement. In this embodiment, four ribs 48 are formed. The recesses 47 are arranged on both sides of each rib 48 in the circumferential direction. The recesses 47 are lightening portions.

[0056] The flanges 14 and 15 are arranged so that their surfaces 43 face each other.

[0057] (Assembly of joint structure) The stub end 11 is inserted into the insertion hole 41 of the flange 14 , and the stub end 12 is inserted into the insertion hole 41 of the flange 15 .

[0058] Packing 13 is disposed between contact surface 23a of stub end 11 and contact surface 23a of stub end 12. Bolts 16 are inserted into bolt holes 42 of flange 14, bolt holes 38 of packing 13, and bolt holes 42 of flange 15. In this embodiment, four bolts 16 are inserted.

[0059] Nut 17 is screwed onto the tip of inserted bolt 16. This fastens flange 14 and flange 15 together, and packing 13 is pressed against stub end 11 and stub end 12.

[0060] The flow path 3 a of the connection structure 3 is formed by the flow path 24 of the stub end 11 , the central hole 30 of the packing 13 , and the flow path 24 of the stub end 12 .

[0061] (Ultrapure water application for connection structure 3) The connection structure 3 according to the embodiment of the present disclosure can be used, for example, for transporting ultrapure water. Specifically, the connection structure 3 for ultrapure water according to the embodiment of the present disclosure can be used as piping within an ultrapure water production apparatus, piping for transporting ultrapure water from the ultrapure water production apparatus to a use point, piping for returning ultrapure water from the use point, etc.

[0062] Ultrapure water is water with extremely high purity, and is suitable for use in cleaning electronic devices such as semiconductor devices. There are many indices for expressing the grade of ultrapure water, but in this embodiment, the electrical resistivity of ultrapure water is 18.2 MΩ cm or more, and the TOC is 50 ppb or less.

[0063] The connection structure 3 according to the embodiment of the present disclosure is preferably a water pipe for nuclear power generation, which has particularly strict requirements for the quality of ultrapure water, or a pipe for transporting ultrapure water used in wet processing steps such as cleaning in the manufacturing process of pharmaceuticals, semiconductor devices, or liquid crystals, more preferably semiconductor devices. The semiconductor devices in question are preferably those with a high degree of integration, and more specifically, those used in manufacturing processes of semiconductor devices with a minimum line width of 65 nm or less. Standards for the quality of ultrapure water used in semiconductor manufacturing include, for example, SEMI F75.

[0064] (Features, etc.) As described above, by inclining the contact surfaces 23a of the stub ends 11 and 12 so as to satisfy the above formula (2), it is possible to increase the crushing of the inner convex portions 32 and 34 of the packing 13. This reduces the gap between the packing 13 and the stub ends 11 and 12, making it possible to suppress the accumulation of particles. Particularly in the field of semiconductor manufacturing, this can improve the yield of semiconductor products.

[0065] Fig. 8 is a schematic diagram showing a state in which packing 13 is compressed by a pair of stub ends 11, 12 in connection structure 3 of this embodiment. Compared to the conventional structure shown in Fig. 11, in connection structure 3 of this embodiment, contact surface 23a is inclined, which increases crushing of inner convex portions 32, 34. This reduces the occurrence of a gap (see gap S in Fig. 11) between stub end 11 and packing 13 on the flow path 3a side of inner convex portion 32, and reduces the occurrence of a gap between stub end 12 and packing 13 on the flow path 3a side of inner convex portion 34.

[0066] (Other embodiments) Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0067] (A) In the above embodiment, the stub end 11 and the stub end 12 have the same configuration, but they may be different as long as the gradient of the contact surface 23a satisfies the above formula (2).

[0068] (B) In the above embodiment, the inclined contact surface 23a is formed over the entire area from the edge 23b of the opening 24b of the end face 11e of the stub end 11 to the outer edge 23c, as shown in FIG. 5, but a portion around the contact surface 23a where no inclination is formed (a portion perpendicular to the axis O) may also be formed.

[0069] (C) In the above embodiment, both the flange 14 and the flange 15 are loose flanges that can rotate relative to the stub end, but either one of them may be a flange that is fixed to the stub end.

[0070] (D) In the above embodiment, the flange 14 and the flange 15 are fastened together by four bolts 16, but the number is not limited to four.

[0071] (E) In the above embodiment, the packing 13 has inner convex portions 32, 34 and outer convex portions 33, 35, but further annular convex portions may be formed outside the outer convex portions 33, 35, or the outer convex portions 33, 35 may not be formed.

[0072] (Example) The above-described embodiment will be described in detail below using examples.

[0073] The diameter of the connecting portion 21 of the stub end 11 and the stub end 12 is set to 25A.

[0074] As shown in FIG. 5, the outer diameter of the flared portion 23 of the stub end 11 and the stub end 12 is d2, and the inner diameter of the flow passage 24 is d3.

[0075] The gradient of the contact surface 23a was calculated using equation (2).

[0076] (h1 / d1)×100(%)...Equation (2) The value of d1 was calculated using the following formula (3).

[0077] d1 = (d2 - d3) / 2 (mm) Equation (3) As design values, d1, d2, and d3 were set to the values ​​in the following table (1), and the gradient value was changed by changing the value of h1. (Table 1) TIFF0007797291000001.tif15143h1 was changed to 1.0 mm, 2.0 mm, and 3.0 mm, and thereby the slope of the contact surface 23a was changed to 2.7%, 5.3%, and 10.7%, and the connection structure 3 was assembled using the stub ends 11 and 12. In this example, the stub ends 11 and 12 used had the same shape.

[0078] A through hole was formed in a portion of the stub end 11 where a gap S may occur, and a water leakage test was conducted. Specifically, as shown in Fig. 9, a through hole Q was formed from a portion of the contact surface 23a of the stub end 11 radially inward of the inner convex portion 32 to the end portion 21a of the stub end 11. The connection structure 3 with such a through hole Q formed therein was connected to a water leakage tester as shown in Fig. 10, and a water leakage test was conducted.

[0079] Flow path 24 in stub end 11 and hand pump 100 are connected by tube 101. Flow path 24 in stub end 12 is blocked. By driving hand pump 100, water is injected from flow path 24 in stub end 11. Hand pump 100 is equipped with a water pressure gauge 102. A test was conducted to determine whether water leaked from through-hole Q when water pressure was applied by hand pump 100.

[0080] A similar water leakage test was also carried out on the contact structure of Comparative Example 1, in which the gradient of the contact surface of the stub end was set to 0%. The test was carried out three times for each of Examples 1 to 3 and Comparative Example 1, and the results for all were as shown in Table 2 below. (Table 2) TIFF0007797291000002.tif27143In the case of Comparative Example 1, water leakage occurred at 0.01 MPa, which indicates that the through-hole Q was not blocked by the packing. That is, in Comparative Example 1, the surface pressure applied to the convex part of the packing was insufficient, which resulted in the formation of a minute gap (see gap S in FIG. 11), and in actual piping, particles would accumulate.

[0081] In Examples 1 to 3, no water leakage occurred even when the water pressure was increased to 1.2 MPa. This shows that sufficient surface pressure is applied to the inner protrusions 32, 34 of the packing 13, eliminating gaps between the packing 13 and the stub ends 11, 12.

[0082] Furthermore, by setting the gradient to 15% or less, uneven tightening is unlikely to occur even if axial misalignment occurs between the packing 13 and the stub ends 11, 12 during installation.

[0083] On the other hand, if the gradient is greater than 15% and uneven tightening occurs, one side of the inner convex portions 32, 34 in the diameter direction will be significantly crushed, but the other side will hardly be crushed at all. As a result, gaps will form between the packing 13 and the stub ends 11, 12, resulting in an increase in particles. Also, since the compressibility of the inner convex portions 32, 34 and part of the outer convex portions 33, 35 of the packing 13 will be insufficient, it is possible that problems will occur such as an inability to ensure long-term watertightness.

[0084] From the above, it can be seen that by setting the gradient (h / d)×100 to 0.5% or more and 18% or less, the gap between the packing 13 and the stub ends 11, 12 can be reduced, and the generation of particles can be suppressed. [Explanation of symbols]

[0085] 11: Stub end 23: Flare section 23a: Contact surface 23b: Edge 24: Flow path 24b:Aperture P1, P2:Position L1, L2: Straight line O: Central axis

Claims

1. A stub end used for connecting pipes and made of a resin material, a flow path through which a liquid flows; a first end portion having a first opening of the flow path and a contact surface disposed around the first opening and in contact with a seal member disposed between the first end portion and a connection object; a second end portion having a second opening of the flow channel opposite the first opening; the contact surface is inclined toward the second end as it becomes more distant from the central axis of the flow channel, and the entire contact surface is inclined from the edge of the first opening to the outer edge thereof, A point on a first line that passes through the edge of the opening and is perpendicular to the central axis of the flow channel, moved from the edge of the opening toward the outside of the contact surface, is defined as a first position; a second line that passes through the first position and is parallel to the central axis and intersects with the contact surface is defined as a second position; the length on the first line from the edge of the opening to the first position is defined as d; and the length on the second line from the first position to the second position is defined as h. 0.5≦(h / d)×100≦18 is satisfied, Stub end.

2. The resin material is polyethylene. The stub end of claim 1 .

3. The resin material is high-density polyethylene. The stub end according to claim 1 or 2.

4. A first stub end according to any one of claims 1 to 3; A second stub end according to any one of claims 1 to 3; a seal member formed of rubber and disposed between the contact surface of the first stub end and the contact surface of the second stub end; a first flange disposed around the first stub end; a second flange disposed about the second stub end; a fastening portion that fastens the first flange and the second flange, the seal member has a flat portion, a first annular convex portion formed on a first surface of the flat portion on the first stub end side, and a second annular convex portion formed on a second surface of the flat portion on the second stub end side, the sealing member is provided with a covering portion that covers the first convex portion and the second convex portion and is made of polytetrafluoroethylene; the first protrusion is compressed by the contact surface of the first stub end, and the second protrusion is compressed by the contact surface of the second stub end. Connection structure.

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