Pipe joint

Abstract

To provide a pipe joint capable of enhancing the degree of freedom in selecting the material of a joint body.SOLUTION: A pipe joint according to the present disclosure includes a tubular joint body having a contact surface that comes into contact with a transfer fluid on an inner periphery and having a male screw portion on an outer periphery, and a union nut having a female screw portion to be fastened to the male screw portion, wherein the joint body includes an inner cylinder member having an inner peripheral surface as the contact surface, and an outer cylinder member disposed separately from the inner cylinder member at a position outside the inner cylinder member in a radial direction and not in contact with the transfer fluid and having the male screw portion on an outer periphery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a pipe fitting. [Background technology]

[0002] A pipe fitting described in Patent Document 1 is known as a connection structure for connecting flow paths formed in fluid devices such as tubes and diaphragm pumps in manufacturing equipment in various technical fields, including semiconductor manufacturing and medical and pharmaceutical manufacturing. The pipe fitting in Patent Document 1 includes an inner ring attached to the inner periphery of one end of the tube, a fitting body attached to the outer periphery of one end of the tube, and a union nut attached to the outer periphery of the fitting body. A flow path through which a transport fluid flows is formed in the fitting body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-168947 Summary of the Invention [Problem to be solved by the invention]

[0004] When the above-mentioned pipe fittings are used in, for example, semiconductor manufacturing, a high level of cleanliness is required for the fitting body, which comes into contact with the transferred fluid. For this reason, the fitting body is molded using a highly pure fluororesin material. However, the fitting body includes non-contacting portions that do not require a high level of cleanliness. Therefore, there is a demand for using materials other than fluororesin for the non-contacting portions in order to reduce the weight of the pipe fitting, reduce manufacturing costs, and reduce the environmental impact.

[0005] An object of the present disclosure is to provide a pipe fitting that allows greater freedom in selecting materials for the fitting body. [Means for solving the problem]

[0006] (1) The pipe fitting of the present disclosure comprises a cylindrical fitting body having a contact surface on its inner circumference that comes into contact with the transported fluid and a male threaded portion on its outer circumference, and a union nut having a female threaded portion that is screwed onto the male threaded portion. The fitting body comprises an inner tube member whose inner surface is the contact surface, and an outer tube member that is provided separately from the inner tube member at a position radially outward of the inner tube member that does not contact the transported fluid and has the male threaded portion on its outer circumference.

[0007] According to the pipe fitting of the present disclosure, the fitting body includes an inner tubular member whose inner circumferential surface is a contact surface that comes into contact with the transfer fluid, and an outer tubular member that is provided separately from the inner tubular member at a position radially outward of the inner tubular member that does not come into contact with the transfer fluid. This allows the outer tubular member, which does not come into contact with the transfer fluid, to be manufactured using a material selected according to objectives such as weight reduction and reduced manufacturing costs. This allows for greater freedom in selecting materials for the fitting body than with conventional fitting bodies made of a single member.

[0008] (2) In the pipe fitting of (1), it is preferable that the fitting body further has a radial protrusion provided on a circumferential portion of one of the inner and outer tube members and protruding radially toward the other member, and a radial groove provided on a circumferential portion of the other member so as to be radially recessed and into which the radial protrusion fits. In this case, the radial protrusions on one of the inner and outer cylindrical members fit into the radial grooves on the other. As a result, when one of the members attempts to rotate circumferentially relative to the other, the circumferential (rotational) ends of the radial protrusions abut against the circumferential ends of the radial grooves. As a result, the inner and outer cylindrical members can be prevented from rotating circumferentially relative to each other.

[0009] (3) In the pipe fitting of (2), it is preferable that the fitting body further has an axial protrusion protruding from the radial protrusion to at least one side in the axial direction, and an axial groove recessed in the radial groove to at least one side in the axial direction, into which the axial protrusion fits. In this case, the axial protrusion on one member fits into the axial groove on the other member. As a result, for example, when a high-temperature transfer fluid comes into contact with the contact surface of the inner cylindrical member and the inner cylindrical member thermally contracts radially inward relative to the outer cylindrical member, the axial protrusion abuts against the axial groove. As a result, the inner cylindrical member can be prevented from contracting radially inward relative to the outer cylindrical member.

[0010] (4) In the pipe joint of (2) or (3) above, it is preferable that the one member is the inner cylindrical member and the other member is the outer cylindrical member. In this case, the radial protrusion provided on the inner tube member fits into the radial groove provided on the outer tube member, thereby preventing the inner tube member and the outer tube member from rotating circumferentially relative to each other.

[0011] (5) In any one of the pipe fittings (2) to (4), the inner tube member is made of synthetic resin, and a gate mark protruding radially outward is formed at a predetermined circumferential position on the outer periphery of the inner tube member, and it is preferable that the radial protrusion is the gate mark. In this case, when the synthetic resin inner tubular member is molded in a mold, the gate marks formed on the outer periphery of the molded inner tubular member can be used as radial protrusions, thereby reducing the manufacturing cost of the joint body. [Effects of the Invention]

[0012] According to the pipe fitting of the present disclosure, the degree of freedom in selecting the material of the fitting body can be increased. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a pipe joint according to a first embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing a main portion of a joint body of the pipe joint. [Figure 3] 4 is a perspective view showing a first protrusion and a second protrusion provided on an inner cylindrical member of the joint body. FIG. [Figure 4]4 is a cross-sectional perspective view showing a first groove portion and a second groove portion provided in the outer cylindrical member of the joint body. FIG. [Figure 5] FIG. 10 is an enlarged cross-sectional view showing a main portion of a joint body of a pipe joint according to a second embodiment. [Figure 6] 6 is a perspective view showing a plurality of radial grooves provided in the inner cylindrical member of FIG. 5. FIG. [Figure 7] 6 is a cross-sectional perspective view showing a plurality of radial protrusions provided on the outer cylindrical member of FIG. 5. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. [First embodiment] <Overall configuration of pipe fittings> 1 is a cross-sectional view showing a pipe fitting 1 according to a first embodiment. The pipe fitting 1 is used, for example, in a piping path through which a chemical liquid used in semiconductor manufacturing equipment flows as a transfer fluid, to connect the flow paths of two fluid devices. In this embodiment, each of the two fluid devices is, for example, a tube 90 made of synthetic resin. The internal space of the tube 90 is formed as a flow path 91 through which the transfer fluid flows.

[0015] Hereinafter, in this specification, the "axial direction" refers to the direction along the axis X of the pipe fitting 1. The "radial direction" refers to the direction perpendicular to the axis X of the pipe fitting 1. The "circumferential direction" refers to the direction around the axis X of the pipe fitting 1. Furthermore, in this specification, the direction from the axial center of the pipe fitting 1 toward both axial sides is referred to as the "axial outward direction," and the direction from both axial sides of the pipe fitting 1 toward the axial center is referred to as the "axial inward direction."

[0016] The pipe fitting 1 comprises a fitting body 2, a pair of inner rings 4, and a pair of union nuts 5. The fitting body 2 is formed in an overall cylindrical shape. The fitting body 2 has an inner tubular member 10 and an outer tubular member 20 provided separately from the inner tubular member 10 and radially outward of the inner tubular member 10. In this embodiment, the inner tubular member 10 and the outer tubular member 20 are both made of synthetic resin. The inner tubular member 10 is primarily molded by injection molding using a mold, and the outer tubular member 20 is secondarily molded by injection molding using a mold radially outward of the primarily molded inner tubular member 10.

[0017] The internal space of the inner cylindrical member 10 is a flow path 11 through which the transfer fluid flows. The inner circumferential surface of the inner cylindrical member 10 is a contact surface 12 that comes into contact with the transfer fluid. The flow path 11 of the inner cylindrical member 10 is connected to each of the communication paths 44 of the pair of inner rings 4. Since the inner cylindrical member 10 comes into contact with the transfer fluid, a high level of cleanliness is required. For this reason, the inner cylindrical member 10 is molded using a highly pure fluororesin material.

[0018] A primary seal groove 13 is formed radially inward at each of both axial outer end portions of the inner cylindrical member 10. The primary seal grooves 13 are tapered grooves that are cut out so that their diameter gradually increases from the contact surface 12, which is the axial inner end, toward the axial outer end. Secondary seal grooves 14 are formed radially outward from each primary seal groove 13 in the inner cylindrical member 10. The secondary seal grooves 14 are formed cylindrically between the primary seal grooves 13 and the receiving portion 22. Fitting portions 15 are formed radially outward from each secondary seal groove 14 in the inner cylindrical member 10. The fitting portions 15 are formed cylindrically on the outer periphery of the inner cylindrical member 10.

[0019] As described above, the outer cylindrical member 20 is disposed radially outward of the inner cylindrical member 10, i.e., at a position not in contact with the transported fluid. The outer cylindrical member 20 is molded from a synthetic resin material according to the purpose. For example, the outer cylindrical member 20 is molded from a recyclable synthetic resin material (such as fluororesin) to reduce the environmental impact. Furthermore, the outer cylindrical member 20 is molded from a synthetic resin material with a low specific gravity (such as polypropylene or polyethylene) to reduce the weight.

[0020] The outer tube member 20 has an outer tube main body portion 21, a pair of socket portions 22, and a pair of male thread portions 23. The outer tube main body portion 21 is formed in the axial center of the outer tube member 20. The pair of socket portions 22 are integrally formed on both axial outer sides of the outer tube main body portion 21. A male thread portion 23 is formed on the outer periphery of each socket portion 22.

[0021] A fitted portion 24 recessed radially outward is formed in the axial center of the inner periphery of the outer tubular member 20. The fitted portion 24 is formed around the entire inner periphery of the outer tubular member 20. The fitting portion 15 of the inner tubular member 10 fits into the fitted portion 24 of the outer tubular member 20.

[0022] The inner ring 4 has a bulge portion 41, a primary seal portion 42, and a secondary seal portion 43. The bulge portion 41 is formed at the axially outer end of the inner ring 4, protruding radially outward in a mountain-like shape. The bulge portion 41 is press-fitted into the end of the tube 90, expanding the diameter of the end. This connects the inner ring 4 to the end of the tube 90.

[0023] The primary seal portion 42 is formed in an annular shape on the radially inner side of the axially inner end of the inner ring 4. The outer peripheral surface of the primary seal portion 42 gradually reduces in diameter from the axially inner end to the axially outer end. The primary seal portion 42 is inserted into and pressed against the primary seal groove 13 of the inner cylindrical member 10. The secondary seal portion 43 is formed in a cylindrical shape on the radially outer side of the axially inner side of the inner ring 4. The secondary seal portion 43 is inserted (press-fitted) into the secondary seal groove 14 of the inner cylindrical member 10.

[0024] The inner ring 4, with the bulge 41 press-fitted onto the end of the tube 90, is fitted into the inner periphery of the socket 22 of the outer tubular member 20. As a result, the end of the tube 90 is clamped between the bulge 41 of the inner ring 4 and the socket 22 of the outer tubular member 20. The inner diameter of the inner ring 4 is the same as the inner diameter of the inner tubular member 10.

[0025] The internal space of the inner ring 4 is defined as a communication passage 44 through which the transfer fluid flows. The communication passage 44 is formed so as to penetrate the inner ring 4 in the axial direction. The communication passage 44 of the inner ring 4 communicates the flow passage 11 of the inner cylindrical member 10 with the flow passage 91 of the tube 90. Therefore, the flow passages 91 of both tubes 90 communicate with each other via the communication passages 44 of each inner ring 4 and the flow passage 11 of the inner cylindrical member 10.

[0026] The union nut 5 is cylindrical and made of a synthetic resin material such as PVC, PP, PE, or fluororesin (such as PFA or PTFE). The union nut 5 has a pressing portion 51 and a female thread portion 52. The pressing portion 51 is formed on the axially outer side of the union nut 5, protruding radially inward. The female thread portion 52 is formed on the axially inner periphery of the union nut 5. The female thread portion 52 is screwed into the male thread portion 23 of the outer cylindrical member 20. As a result of this screwing, the axially inner end of the pressing portion 51 presses against the outer peripheral surface of the tube 90, which is bulging radially outward due to the bulging portion 41.

[0027] With the above configuration, when the female thread portion 52 of the union nut 5 is tightened onto the male thread portion 23 of the outer tubular member 20, the primary seal portion 42 and secondary seal portion 43 of the inner ring 4 are inserted into the primary seal groove 13 and secondary seal groove 14 of the inner tubular member 10, respectively. This ensures sealing performance at the connection between the fitting body 2 (inner tubular member 10) and the inner ring 4, as well as sealing performance between the outer peripheral surface of the inner ring 4 and the inner peripheral surface of the outer tubular member 20 (receiving portion 22). In addition, the pressing portion 51 of the union nut 5 can prevent the end of the tube 90 from slipping out of the pipe fitting 1.

[0028] <Regulatory structure> 2 is an enlarged cross-sectional view showing a main portion of the joint body 2. The joint body 2 further has a restriction structure 30 that restricts relative movement between the inner tubular member 10 and the outer tubular member 20. The restriction structure 30 of this embodiment includes a first protrusion 31 and a second protrusion 32 (FIG. 3) provided on the inner tubular member 10, and a first groove 33 and a second groove 34 (FIG. 4) provided on the outer tubular member 20.

[0029] Fig. 3 is a perspective view showing a first protrusion 31 and a second protrusion 32 provided on the inner tube member 10. In Fig. 2 and Fig. 3, the first protrusion 31 and the second protrusion 32 are both made of synthetic resin, and are molded integrally with the inner tube member 10 when the inner tube member 10 is primarily molded. The first protrusion 31 is formed in a substantially T-shape in an axial cross section (FIG. 2). The first protrusion 31 has a radial protrusion 311 and a pair of axial protrusions 312.

[0030] The radial protrusion 311 is provided in the axial center of the outer circumferential surface 16 of the inner cylindrical member 10, protruding radially outward toward the outer cylindrical member 20. The radial protrusion 311 is provided on a portion of the circumferential direction of the inner cylindrical member 10. The radial protrusion 311 of this embodiment is provided in an arc shape over a range of 300° in the circumferential direction of the inner cylindrical member 10. The radial protrusion 311 has an end 311a on one circumferential side (clockwise side in FIG. 3) and an end 311b on the other circumferential side (counterclockwise side in FIG. 3).

[0031] The axial protrusions 312 are provided so as to protrude outward in the axial direction from the radial outer end (protruding end) of the radial protrusion 311. Each axial protrusion 312 is provided in an arc shape over the entire circumferential direction of the radial protrusion 311. Therefore, like the radial protrusions 311, the axial protrusions 312 are provided on part of the circumferential direction of the inner cylindrical member 10. A contact surface 312a extending axially outward from the radial protrusion 311 is formed on the radial inner side of the axial protrusion 312.

[0032] The second protrusion 32 has only a radial protrusion 321. The radial protrusion 321 is provided at a predetermined circumferential location in the axial center of the outer peripheral surface 16 of the inner tube member 10, protruding radially outward toward the outer tube member 20. The radial protrusion 321 of the second protrusion 32 of this embodiment is provided on the outer peripheral surface 16 of the inner tube member 10 between the circumferentially opposite end portions 311 a, 311 b of the radial protrusion 311 of the first protrusion 31.

[0033] The radial protrusion 321 is a gate mark formed by protruding radially outward at the predetermined location on the outer peripheral surface 16 of the inner cylindrical member 10. The gate mark is a shear mark formed when a gate (not shown) of the mold is separated after the inner cylindrical member 10 is primarily molded by injection molding using the mold.

[0034] The radial protrusion 321 is formed in a substantially rectangular shape when viewed from the radial outside. The radial protrusion 321 has an end portion 321a on one circumferential side and an end portion 321b on the other circumferential side. The radial height of the radial protrusion 321 is smaller than the radial height of the radial protrusion 311. The axial length of the radial protrusion 321 is longer than the axial length of the radial protrusion 311.

[0035] 4 is a cross-sectional perspective view showing the first groove portion 33 and the second groove portion 34 provided in the outer tubular member 20. In FIGS. 2 to 4, the first groove portion 33 and the second groove portion 34 are formed along the outer shape of the first protrusion portion 31 on the inner tubular member 10 side on the inner circumferential surface (bottom surface) 24a of the fitted portion 24 of the outer tubular member 20 during secondary molding of the outer tubular member 20. The first groove portion 33 has a radial groove portion 331 and a pair of axial groove portions 332.

[0036] The radial groove 331 is recessed radially outward in the axial center of the inner circumferential surface 24a of the outer tubular member 20. The radial groove 331 is provided on a portion of the inner circumferential surface 24a of the outer tubular member 20 in the circumferential direction. The radial groove 331 in this embodiment is provided in an arc shape over a range of 300° in the circumferential direction of the outer tubular member 20. The radial groove 331 has an end 331a on one circumferential side (clockwise side in FIG. 4) and an end 331b on the other circumferential side (counterclockwise side in FIG. 4).

[0037] The radial protrusion 311 of the first protrusion 31 is fitted into the radial groove 331 of the first groove 33. As a result, when the inner tube member 10 and the outer tube member 20 attempt to rotate relatively to one side in the circumferential direction around the axis X, the end 311a on one side in the circumferential direction of the radial protrusion 311 abuts against the end 331a on one side in the circumferential direction of the radial groove 331. Furthermore, when the inner tube member 10 and the outer tube member 20 attempt to rotate relatively to the other side in the circumferential direction around the axis X, the end 311b on the other side in the circumferential direction of the radial protrusion 311 abuts against the end 331b on the other side in the circumferential direction of the radial groove 331. As a result, the inner tube member 10 and the outer tube member 20 can be prevented from rotating relatively to both sides in the circumferential direction.

[0038] The axial grooves 332 of the first groove portion 33 are recessed from the radial outer end (groove bottom) of the radial groove 331 to both axially outer sides. Each axial groove 332 is provided in an arc shape over the entire circumferential direction of the radial groove 331. Therefore, like the radial grooves 331, the axial grooves 332 are provided in part of the circumferential direction of the outer tube member 20. Abutment surfaces 332a extending axially outward from the radial grooves 331 are formed on the radially inner side of the axial grooves 332.

[0039] The axial protrusions 312 of the first protrusion 31 are fitted into the axial grooves 332 of the first groove 33. In this state, for example, when a high-temperature transfer fluid passes through the flow path 11 of the inner cylindrical member 10 and comes into contact with the contact surface 12 of the inner cylindrical member 10, the inner cylindrical member 10 tends to thermally contract radially inward relative to the outer cylindrical member 20. At that time, the abutting surfaces 312a of the axial protrusions 312 abut against the abutted surfaces 332a of the axial grooves 332, so that the inner cylindrical member 10 can be prevented from contracting radially inward relative to the outer cylindrical member 20.

[0040] The second groove portion 34 of the outer tube member 20 is formed along the outer shape of the second protrusion 32 of the inner tube member 10. The second groove portion 34 has only a radial groove portion 341. The radial groove portion 341 is recessed radially outward at a predetermined circumferential location in the axial center of the inner circumferential surface 24a of the outer tube member 20. The radial groove portion 341 of the second groove portion 34 of this embodiment is provided on the inner circumferential surface 24a of the outer tube member 20 between the circumferentially opposite end portions 331a, 331b of the radial groove portion 331 of the first groove portion 33.

[0041] The radial groove 341 is formed in a substantially rectangular shape when viewed from the radially inward direction. The radial groove 341 has an end 341a on one circumferential side and an end 341b on the other circumferential side. The radial depth of the radial groove 341 is shallower than the radial depth of the radial groove 331. The axial length of the radial groove 341 is longer than the axial length of the radial groove 331.

[0042] The radial protrusion 321 of the second protrusion 32 is fitted into the radial groove 341 of the second groove 34. As a result, when the inner tube member 10 and the outer tube member 20 attempt to rotate relatively to one circumferential side around the axis X, the end 321a on one circumferential side of the radial protrusion 321 abuts against the circumferential end 341a of the radial groove 341. Furthermore, when the inner tube member 10 and the outer tube member 20 attempt to rotate relatively to the other circumferential side around the axis X, the end 321b on the other circumferential side of the radial protrusion 321 abuts against the circumferential end 341b of the radial groove 341. As a result, the inner tube member 10 and the outer tube member 20 can be further prevented from rotating relatively to both sides in the circumferential direction.

[0043] <Action and effect> According to the pipe fitting 1 of the first embodiment, the fitting body 2 has an inner cylindrical member 10 whose inner circumferential surface is a contact surface 12 that comes into contact with the transferred fluid, and an outer cylindrical member 20 that is disposed separately from the inner cylindrical member 10 at a position radially outward of the inner cylindrical member 10 that does not come into contact with the transferred fluid. This allows the outer cylindrical member 20, which does not come into contact with the transferred fluid, to be manufactured using a material selected according to objectives such as weight reduction and reduced manufacturing costs. This allows for greater freedom in selecting materials for the fitting body 2 than for a conventional fitting body 2 made of a single member.

[0044] The radial protrusions 311, 321 provided on the inner tube member 10 fit into the radial grooves 331, 341 provided on the outer tube member 20. As a result, when the inner tube member 10 and the outer tube member 20 attempt to rotate relatively in the circumferential direction, the circumferential (rotational) end portions 311a (311b), 321a (321b) of the radial protrusions 311, 321 abut against the circumferential end portions 331a (331b), 341a (341b) of the radial grooves 331, 341. As a result, the inner tube member 10 and the outer tube member 20 can be prevented from rotating relatively in the circumferential direction.

[0045] The axial protrusion 312 on the inner cylindrical member 10 side fits into the axial groove 332 on the outer cylindrical member 20 side. As a result, when, for example, a high-temperature transfer fluid comes into contact with the contact surface 12 of the inner cylindrical member 10 and the inner cylindrical member 10 attempts to thermally contract radially inward relative to the outer cylindrical member 20, the axial protrusion 312 abuts against the axial groove 332. As a result, the inner cylindrical member 10 can be prevented from contracting radially inward relative to the outer cylindrical member 20.

[0046] The radial protrusion 321 of the second protrusion 32 is a gate mark formed on the outer circumferential surface 16 of the inner cylindrical member 10 so as to protrude radially outward. Therefore, when the inner cylindrical member 10 is subjected to primary molding using a mold, the gate mark formed on the outer periphery of the inner cylindrical member 10 after primary molding can be used as the radial protrusion 321. This allows the manufacturing cost of the joint body 2 to be reduced.

[0047] <Modification> In this embodiment, the radial protrusions 311, 321 are provided in the axial center of the outer circumferential surface 16 of the inner cylindrical member 10, but they may be provided on the axial outer side of the outer circumferential surface 16 of the inner cylindrical member 10. In this case, the radial grooves 331, 341 are provided on the axial outer side of the inner circumferential surface 24a of the outer cylindrical member 20 in accordance with the radial protrusions 311, 321. A plurality of the radial protrusions 311, 321 and the radial grooves 331, 341 may be provided in the axial direction of the inner cylindrical member 10 and the outer cylindrical member 20.

[0048] The axial protrusions 312 in this embodiment are provided on both axial sides of the radial protrusion 311, but may be provided on only one axial side of the radial protrusion 311. The radial protrusions 321 in this embodiment are gate marks, but like the radial protrusions 311, they may be provided separately from the gate marks.

[0049] In this embodiment, the first protrusions 31 (radial protrusions 311 and axial protrusions 312) are provided on the outer periphery of the inner cylindrical member 10, but may be provided on the inner periphery of the outer cylindrical member 20. In that case, the first grooves 33 (radial grooves 331 and axial grooves 332) are provided on the outer periphery of the inner cylindrical member 10. Similarly, the second protrusions 32 (radial protrusions 321) are provided on the outer periphery of the inner cylindrical member 10, but may be provided on the inner periphery of the outer cylindrical member 20. In that case, the second grooves 34 (radial grooves 341) are provided on the outer periphery of the inner cylindrical member 10.

[0050] The regulating structure 30 of this embodiment has a first protrusion 31 and a first groove portion 33, and a second protrusion 32 and a second groove portion 34, but may have only the first protrusion 31 and the first groove portion 33, or only the second protrusion 32 and the second groove portion 34.

[0051] [Second embodiment] 5 is an enlarged cross-sectional view showing a main portion of the joint body 2 of the pipe joint 1 according to the second embodiment. In this embodiment, the configuration of the restriction structure 30 differs from that of the first embodiment. The restriction structure 30 of this embodiment includes a plurality of radial grooves 36 provided in the inner tubular member 10 and a plurality of radial protrusions 37 provided in the outer tubular member 20.

[0052] Fig. 6 is a perspective view showing a plurality of radial grooves 36 provided in the inner cylindrical member 10. In Figs. 5 and 6, the plurality of radial grooves 36 are formed in the outer peripheral surface 16 of the inner cylindrical member 10 when the inner cylindrical member 10 is subjected to primary molding. Each radial groove 36 is recessed radially inward in the outer peripheral surface 16 of the inner cylindrical member 10. Each radial groove 36 is provided in a portion of the outer peripheral surface 16 of the inner cylindrical member 10 in the circumferential direction.

[0053] The radial grooves 36 of this embodiment are provided in two rows spaced apart in the axial direction on the outer peripheral surface 16 of the inner cylindrical member 10, with two radial grooves 36 provided in each row in the circumferential direction of the inner cylindrical member 10. That is, in this embodiment, a total of four radial grooves 36 are provided on the outer peripheral surface 16 of the inner cylindrical member 10. The two radial grooves 36 in each row are spaced apart in the circumferential direction of the inner cylindrical member 10, and each radial groove 36 is provided in an arc shape over a circumferential range of approximately 170°. Each radial groove 36 has an end 36a on one circumferential side (clockwise side in FIG. 6) and an end 36b on the other circumferential side (counterclockwise side in FIG. 6).

[0054] 7 is a cross-sectional perspective view showing a plurality of radial protrusions 37 provided on the outer tube member 20. In FIGS. 5 to 7, the plurality of radial protrusions 37 are all made of synthetic resin and are molded integrally with the outer tube member 20 when the outer tube member 20 is subjected to secondary molding. At this time, each radial protrusion 37 is molded by filling each radial groove 36 on the inner tube member 10 side with a resin material. Each radial protrusion 37 is provided on the inner circumferential surface 24a of the outer tube member 20 so as to protrude radially inward toward the inner tube member 10. Each radial protrusion 37 is provided on a portion of the outer tube member 20 in the circumferential direction.

[0055] The radial protrusions 37 of this embodiment are provided in two rows spaced apart in the axial direction on the inner circumferential surface 24a of the outer tubular member 20, with two radial protrusions in each row provided in the circumferential direction of the outer tubular member 20. That is, in this embodiment, a total of four radial protrusions 37 are provided on the inner circumferential surface 24a of the outer tubular member 20. The two radial protrusions 37 in each row are spaced apart in the circumferential direction of the outer tubular member 20, and each radial protrusion 37 is provided in an arc shape over a circumferential range of approximately 170°. Each radial protrusion 37 has an end 37a on one circumferential side (clockwise side in FIG. 7) and an end 37b on the other circumferential side (counterclockwise side in FIG. 7).

[0056] Each radial protrusion 37 on the outer tube member 20 side is fitted into a radial groove 36 on the inner tube member 10 side. As a result, when the inner tube member 10 and the outer tube member 20 attempt to rotate relatively in one circumferential direction around the axis X, an end 37a on one circumferential side of each radial protrusion 37 abuts against an end 36a on one circumferential side of each radial groove 36. Furthermore, when the inner tube member 10 and the outer tube member 20 attempt to rotate relatively in the other circumferential direction around the axis X, an end 37b on the other circumferential side of each radial protrusion 37 abuts against an end 36b on the other circumferential side of each radial groove 36. As a result, the inner tube member 10 and the outer tube member 20 can be prevented from rotating relatively in both circumferential directions.

[0057] Other configurations of this embodiment are the same as those of the first embodiment, so the same reference numerals are used and the description thereof will be omitted.

[0058] <Action and effect> According to the pipe fitting 1 of the second embodiment, the fitting body 2 has an inner tubular member 10 and an outer tubular member 20 that is arranged separately from the inner tubular member 10 at a position that does not contact the transferred fluid. This allows the outer tubular member 20, which does not contact the transferred fluid, to be manufactured using a material selected according to the purpose, such as weight reduction and reduced manufacturing costs. Therefore, the degree of freedom in selecting the material for the fitting body 2 is greater than in the conventional fitting body 2 made of a single member.

[0059] Furthermore, the radial protrusions 37 provided on the outer tube member 20 fit into the radial grooves 36 provided on the inner tube member 10. As a result, when the inner tube member 10 and the outer tube member 20 attempt to rotate relatively in the circumferential direction, the circumferential (rotational) end 37a (37b) of the radial protrusion 37 abuts against the circumferential end 36a (36b) of the radial groove 36. As a result, the inner tube member 10 and the outer tube member 20 can be prevented from rotating relatively in the circumferential direction.

[0060] <Modification> The radial protrusion 37 of this embodiment may be provided with an axial protrusion that protrudes axially outward, as in the first embodiment. In this case, the radial groove 36 is provided with an axial groove into which the axial protrusion fits.

[0061] In this embodiment, the multiple radial protrusions 37 are provided on the inner circumference of the outer tubular member 20, but at least one radial protrusion 37 may be provided on the outer circumference of the inner tubular member 10. In that case, the corresponding radial groove 36 is provided on the inner circumference of the outer tubular member 20. For example, of the two axial rows of radial protrusions 37, one row (two) of the radial protrusions 37 may be provided on the outer circumference of the inner tubular member 10. In that case, the two radial grooves 36 corresponding to that row are provided on the inner circumference of the outer tubular member 20.

[0062] [others] The above-disclosed embodiments are illustrative in all respects and are not limiting. For example, the pipe fitting 1 of the present disclosure can be applied not only to semiconductor manufacturing equipment but also to the liquid crystal / organic electroluminescence (EL) field, medical / pharmaceutical field, and automotive-related field. [Explanation of symbols]

[0063] 1 Pipe fittings 2 Joint members 5 union nuts 10 Inner cylinder member 12 Contact surface 20 outer cylinder member 23 Male thread 36 Radial groove 37 Radial protrusion 52 Female thread 311 Radial protrusion 312 Axial protrusion 321 Radial protrusion (gate mark) 331 Radial groove 332 Axial groove 341 Radial groove

Claims

1. a cylindrical joint body having an inner periphery with a contact surface that comes into contact with the transported fluid and an outer periphery with a male thread portion; a union nut having a female thread portion that is fastened to the male thread portion, The joint body includes: an inner cylindrical member whose inner circumferential surface is the contact surface; a cylindrical outer member provided separately from the cylindrical inner member at a position radially outward of the cylindrical inner member and not in contact with the fluid being transferred, the cylindrical outer member having the male thread portion on its outer periphery;

2. The joint body includes: a radial protrusion provided at a circumferential portion of one of the inner and outer cylindrical members and protruding radially toward the other member; 2. The pipe joint according to claim 1, further comprising a radial groove recessed in a circumferential portion of the other member, the radial groove receiving the radial protrusion.

3. The joint body includes: an axial protrusion provided so as to protrude from the radial protrusion to at least one axial side; 3. The pipe fitting according to claim 2, further comprising an axial groove portion recessed in at least one axial direction side of the radial groove portion, into which the axial protrusion is fitted.

4. the one member is the inner cylindrical member, 4. The pipe joint according to claim 2, wherein the other member is the outer cylindrical member.

5. the inner cylindrical member is made of synthetic resin, a gate mark protruding radially outward is formed at a predetermined circumferential position on the outer periphery of the inner cylindrical member, The pipe joint according to claim 4 , wherein the radial protrusion is the gate mark.

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