Electric fusion joint, pipe system, electric fusion joint with pipe and pipe rehabilitation structure

Abstract

To provide an electric fusion joint capable of preventing two terminals from being damaged, and capable of suppressing liquid flowing in a joint body from leaking from a portion in which the two terminals are arranged in the joint body.SOLUTION: An electric fusion joint 21 comprises a joint body 22 having a first opening 22b formed at a first end 22a in a direction of its axial line O1, an electric wire 24A embedded in the joint body, and two terminals 29A arranged in the joint body closer to a first end than the electric wire in an axial direction and detachable to both end parts of the electric wire.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electrofusion joint, a piping system, an electrofusion joint with a pipe, and a pipe rehabilitation structure. [Background technology]

[0002] Conventionally, existing piping has been rehabilitated by placing a resin pipe (piping) inside the existing piping (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-170367 Summary of the Invention [Problem to be solved by the invention]

[0004] When a long polyethylene resin pipe is required, a plurality of resin pipes are fused together via electric fusion joints to increase the overall length of the plurality of resin pipes. A conventional electrofusion joint comprises a joint body, an electric wire, and two terminals. The joint body is formed in a cylindrical shape. The electric wire is embedded in the joint body. The two terminals protrude radially outward from the outer peripheral surface of the joint body and are electrically connected to both ends of the electric wire. The two terminals are arranged on the joint body with a gap in the axial direction of the joint body.

[0005] However, when a conventional electrofusion joint and a plastic pipe are used and the electrofusion joint and the plastic pipe are placed inside an existing pipe to rehabilitate the existing pipe, there is a risk that the two terminals of the electrofusion joint may get caught on the existing pipe and be damaged. Furthermore, the thickness of the joint body is thin in the area where the two terminals are located in order to ensure a structure for arranging the two terminals. Therefore, when the plastic pipe is fused to the joint body, water (liquid) flowing inside the joint body may pass between the joint body and the plastic pipe and leak from the area where the two terminals are located.

[0006] The present invention has been made to solve these problems, and aims to provide an electrofusion joint, a piping system, an electrofusion joint with piping, and a piping rehabilitation structure that suppresses damage to the two terminals and prevents liquid flowing inside the joint body from leaking from the part of the joint body where the two terminals are located. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. (1) A first aspect of the present invention is an electric fusion joint comprising: a joint body having a first opening formed at a first end in the axial direction of the joint body; an electric wire embedded in the joint body; and two terminals that are disposed in the joint body closer to the first end than the electric wire in the axial direction and are detachable from both ends of the electric wire.

[0008] In this invention, the two terminals are detachable from both ends of the electric wire. Therefore, by detaching the two terminals in advance, for example, before moving the electric fusion joint, it is possible to prevent the two terminals from being damaged when the electric fusion joint is placed in the existing piping to rehabilitate the existing piping. Furthermore, the two terminals are disposed on the joint body closer to the first end than the electric wire in the axial direction. Therefore, when a pipe is disposed within the joint body through the first opening of the joint body, pressure from the liquid flowing within the joint body is likely to act between the end of the pipe and the joint body, which is the upstream side where liquid would leak from between the joint body and the pipe. On the other hand, this pressure is less likely to act on the portion of the joint body where the two terminals are disposed, which is the downstream side where liquid would leak from between the joint body and the pipe. Therefore, it is possible to prevent liquid from leaking from the portion of the joint body where the two terminals are disposed.

[0009] (2) A second aspect of the present invention may be the electric fusion joint described in (1), in which the joint body is formed in a cylindrical shape and has a protrusion that protrudes radially inward and is located on the inner circumferential surface of the joint body on the opposite side of the electric wire from the first end in the axial direction. In this invention, for example, when inserting a pipe into the joint body, the pipe can be abutted against the protruding portion, thereby easily positioning the pipe within the joint body.

[0010] (3) A third aspect of the present invention may be the electric fusion joint described in (1) or (2), which includes a protective member that is formed in a cylindrical shape, protrudes radially outward from the joint body, and surrounds the terminal, and the outer diameter of the protective member gradually increases as it approaches the axis. In this invention, the protective member protects the terminal and also makes the protective member less likely to break when the protective member gets caught on an existing pipe, for example.

[0011] (4) A fourth aspect of the present invention is a piping system comprising an electrofusion joint according to any one of (1) to (3) and a pipe having an end portion disposed within the joint body through the opening, wherein the outer diameter of the joint body and the outer diameter of the pipe are equal to each other. In this invention, a larger cross-sectional area can be ensured within the pipe through which the liquid passes, compared to when the outer diameter of the pipe is smaller than the outer diameter of the joint body.

[0012] (5) A fifth aspect of the present invention is an electric fusion joint with piping, comprising the electric fusion joint according to any one of (1) to (3) and a pipe connected to the joint body so as to communicate with a second opening formed at a second end of the joint body. In this invention, an electrofusion joint can be constructed by extending the portion where the pipe is connected, which prevents damage to the two terminals and prevents the liquid flowing inside the joint body from leaking from the portion of the joint body where the two terminals are located.

[0013] (6) A sixth aspect of the present invention is a pipe rehabilitation structure comprising an existing pipe and the piping system according to (4) arranged within the existing pipe. In this invention, a pipe rehabilitation structure can be constructed using a piping system that ensures a wide cross-sectional area through which liquid passes within the piping. [Effects of the Invention]

[0014] The electrofusion joint, piping system, electrofusion joint with piping, and piping rehabilitation structure of the present invention can prevent damage to the two terminals and also prevent liquid flowing within the joint body from leaking from the portion of the joint body where the two terminals are located. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional side view of a pipe rehabilitation structure according to a first embodiment of the present invention. [Figure 2] 3 is a cross-sectional side view of a main part of the piping system of the pipe rehabilitation structure. FIG. [Figure 3] 10A to 10C are cross-sectional views illustrating a procedure for rehabilitating an existing pipe using the piping system. [Figure 4] 10A to 10C are cross-sectional views illustrating a procedure for rehabilitating an existing pipe using the piping system. [Figure 5] 10A to 10C are cross-sectional views illustrating a procedure for rehabilitating an existing pipe using the piping system. [Figure 6] 10A to 10C are cross-sectional views illustrating a procedure for rehabilitating an existing pipe using the piping system. [Figure 7] FIG. 6 is a cross-sectional side view of a main part of a pipe rehabilitation structure according to a second embodiment of the present invention. [Figure 8] FIG. 10 is a cross-sectional side view of a main part of a piping system according to a third embodiment of the present invention. [Figure 9] 4A to 4C are cross-sectional views illustrating the procedure for constructing the piping system. [Figure 10] FIG. 10 is a cross-sectional side view of a main part of a piping system according to a fourth embodiment of the present invention. [Figure 11] 4A to 4C are cross-sectional views illustrating the procedure for constructing the piping system. [Figure 12] FIG. 10 is a cross-sectional view of an electrofusion joint according to a fifth embodiment of the present invention. [Figure 13] FIG. 13 is a front view seen from the direction of an arrow XIII in FIG. [Figure 14] FIG. 13 is a front view seen from the direction of an arrow XIV in FIG. [Figure 15] FIG. 13 is a cross-sectional view taken along line XV-XV in FIG. 12. [Figure 16] 1 is a flowchart illustrating a method for manufacturing an electrofusion joint according to the present embodiment. [Figure 17] FIG. 10 is an explanatory view showing how the distance between the first fixing part and the second fixing part is widened to allow placement of a resin tube in the joint setting step of the manufacturing method for an electrofusion joint. [Figure 18] 10 is an explanatory view showing how the resin pipe is temporarily fastened to the first fixing part in the joint setting step. FIG. [Figure 19] 10 is an explanatory view showing how the resin pipe is fixed to the first fixing portion and the second fixing portion in the joint setting step. FIG. [Figure 20] FIG. 2 is an explanatory diagram of a heating wire embedding portion used in the wire embedding portion cutting and embedding step in the manufacturing method of an electric fusion joint. [Figure 21] 10 is an explanatory view showing embedding a first heating wire into the inner circumferential surface of the first resin pipe portion in the wire-embedding portion cutting and embedding step. FIG. [Figure 22] FIG. 1 is a side view of a modified example 1(1) of an electrofusion joint. [Figure 23]FIG. 10 is an explanatory diagram showing how first fixing marks are provided on the first resin pipe portion of Modification 1(1). [Figure 24] FIG. 10 is a side view of a modified example 1(2) of the electrofusion joint. [Figure 25] FIG. 10 is a side view of a second modified example of an electrofusion joint. [Figure 26] FIG. 26 is a plan view seen from the direction of the arrow XXVI in FIG. 25. [Figure 27] FIG. 10 is a front view showing a first heating wire of a modified example 3(1) of an electric fusion joint. [Figure 28] FIG. 10 is a front view showing a first heating wire of a modified example 3(2) of the electric fusion joint. [Figure 29] FIG. 10 is a front view showing a first heating wire of a third modified example (3) of the electric fusion joint. [Figure 30] FIG. 2 is a cross-sectional view of a mold for manufacturing a resin pipe. [Figure 31] FIG. 10 is a perspective view of the main parts of an electric fusion joint with pipe according to a sixth embodiment of the present invention. [Figure 32] FIG. 13 is a side view of an electric fusion joint with pipe according to a seventh embodiment of the present invention. [Figure 33] FIG. 13 is a cross-sectional view of an electric fusion joint with a pipe according to an eighth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] (First embodiment) A first embodiment of an electrofusion joint, a piping system, and a piping rehabilitation structure according to the present invention will be described below with reference to FIGS. 1, a pipe rehabilitation structure 1 of this embodiment includes an existing pipe 10 and a piping system 15 of this embodiment. Note that the piping system 15 can be applied to the pipe rehabilitation structure 1, but the application of the piping system 15 is not limited to the pipe rehabilitation structure 1. The existing pipe 10 is buried at a predetermined depth in the ground G1. For example, the existing pipe 10 is a sewer pipe made of a metal such as carbon steel. The existing pipe 10 extends along a horizontal plane.

[0017] A buried hole G6 is formed in the ground G1. The buried hole G6 crosses the ground surface. The existing pipe 10 is disposed in the buried hole G6. An entrance-side pit G7 and an exit-side pit G8 are formed in the ground G1. The entrance-side pit G7 and the exit-side pit G8 extend downward from the ground surface G2, which is the upper surface of the ground G1, and reach the buried hole G6. The entrance-side pit G7 and the exit-side pit G8 are arranged at intervals from each other along a horizontal plane. Here, the side of the buried hole G6 that is adjacent to the outlet hole G8 relative to the inlet hole G7 is defined as the tip side D1 and the side of the buried hole G6 that is adjacent to the inlet hole G7 relative to the outlet hole G8 is defined as the base side D2.

[0018] The piping system 15 is arranged within an existing piping 10. As shown in Figures 1 and 2, the piping system 15 includes a piping 16 and an electrofusion joint 21 of this embodiment. In Figure 1, two first terminal units 26A and two second terminal units 26B (described later) have been detached from the electrofusion joint 21. The pipe 16 is formed in a straight pipe shape. The pipe 16 is preferably made of a thermoplastic resin such as a polyolefin resin.

[0019] The melt mass flow rate (MFR) of the thermoplastic resin is, for example, preferably 0.1 to 25 g / 10 min, more preferably 0.1 to 10 g / 10 min, and even more preferably 0.29 to 0.45 g / 10 min. When the MFR is equal to or greater than the lower limit, molding becomes easy. When the MFR is equal to or less than the upper limit, thermal stability can be further improved. MFR can be measured in accordance with JIS K 7210:1999 at a test temperature of 220°C and a test load of 10 kg.

[0020] The specific gravity of the thermoplastic resin is, for example, 942 to 953 kg / m 3The specific heat of the thermoplastic resin is preferably, for example, 1.9 to 2.3 kJ / kg·K. The thermal conductivity of the thermoplastic resin is preferably, for example, 0.46 to 0.5 W / m·K. The melting point of the thermoplastic resin (i.e., the melting temperature of the pipe 16) is preferably 150°C to 260°C, and more preferably 180°C to 240°C. The resin material may contain, in addition to the thermoplastic resin, known additives such as pigments, ultraviolet absorbers, antioxidants, and lubricants, as well as fillers.

[0021] The pipe 16 may be a single-layer pipe, or may have a multi-layer structure with a surface layer on at least one of the outer and inner surfaces. The surface layer may contain, for example, at least one of inorganic fibers and organic fibers. Examples of inorganic fibers include glass fibers, carbon fibers, silicon-titanium-carbon composite fibers, boron fibers, and metal fibers. Examples of organic fibers include aramid fibers, vinylon fibers, polyester fibers, and polyamide fibers. If the surface layer contains these fibers, the tensile strength of the pipe 16 can be increased and thermal expansion can be further suppressed. The surface layer may also contain a fluororesin, which can improve resistance to acids, alkalis, and the like (chemical resistance). Furthermore, a layer similar to the surface layer may be provided inside the wall of the pipe 16 .

[0022] The pipe 16 may be a multi-layer pipe having three or more layers including a metal layer as an intermediate layer. Suitable metal materials for the metal layer include, for example, iron, brass, copper, stainless steel, aluminum, titanium, and silver alloy.

[0023] Polyolefin resins have a higher tensile breaking elongation than rigid polyvinyl chloride pipes, measured according to JIS K 6815-1 and JIS K 6815-3. While the tensile breaking elongation of rigid polyvinyl chloride pipes is 50 to 150%, the tensile breaking elongation of polyolefin resin pipes is 350% or more. In particular, by the extrapolation method specified in ISO / TR9080, PE100 high-density polyethylene pipes have a tensile breaking elongation of 500% or more, which can better prevent damage caused by earthquakes.

[0024] The polyolefin resin is not particularly limited, but suitable examples include polyethylene, polypropylene, polybutene, atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, poly-α-olefin, etc. Among these, it is desirable to use polyethylene from the viewpoint of strength, etc. When selecting polyethylene, it is desirable to select any of low-density polyethylene, medium-density polyethylene, high-density polyethylene, etc. as appropriate depending on the durability desired for the pipe 16. From the viewpoint of not affecting earthquake resistance, durability, water quality, etc., a polyethylene resin pipe 16 can be used. In particular, when the pipe 16 is used as a drinking water pipe, a high-density polyethylene resin pipe is preferable.

[0025] 2, the electrofusion joint 21 is a socket-type joint having two openings 22b and 22d, which will be described later. Both ends of the electrofusion joint 21 are sockets. The electrofusion joint 21 includes a joint body 22, a protruding portion 23, a first electric wire (electric wire) 24A, a second electric wire (electric wire) 24B, two first female screw portions 25A, two second female screw portions 25B, two first terminal units 26A, and two second terminal units 26B. 2 shows only one each of the first female screw portion 25A, the second female screw portion 25B, the first terminal unit 26A, and the second terminal unit 26B. The electrofusion joint 21 does not have to have the protrusion 23. Only one end of the electrofusion joint may be a socket.

[0026] Here, the joint body 22 is formed in a cylindrical shape, and the protruding portion 23 is formed in an annular shape. The central axes of the joint body 22 and the protruding portion 23 are arranged coaxially with a common axis. Hereinafter, the common axis will be referred to as the axis O1. The axis O1 is the axis of the joint body 22. The direction perpendicular to the axis O1 is called the radial direction, and the direction going around the axis O1 is called the circumferential direction. The electric fusion joint 21 is disposed so that the axis O1 is aligned with the embedded hole G6. The shape of the joint body 22 is not limited to a cylindrical shape, but may be a square cylindrical shape or the like.

[0027] In this embodiment, the configurations of the first electric wire 24A, the first female screw portion 25A, and the first terminal unit 26A and the configurations of the second electric wire 24B, the second female screw portion 25B, and the second terminal unit 26B are plane-symmetrical with respect to a reference plane S1 perpendicular to the axis O1. Therefore, the configurations of the first electric wire 24A, the first female screw portion 25A, and the first terminal unit 26A are indicated by adding the capital letter "A" to the numerals of the reference symbols. The configurations of the second electric wire 24B, the second female screw portion 25B, and the second terminal unit 26B corresponding to the first electric wire 24A, the first female screw portion 25A, and the first terminal unit 26A are indicated by adding the capital letter "B" to the numerals of the reference symbols of the first electric wire 24A, the first female screw portion 25A, and the first terminal unit 26A. This avoids redundant explanation. For example, the first electric wire 24A and the second electric wire 24B are symmetrical with respect to the reference plane S1.

[0028] The second embodiment and subsequent embodiments described below are similar to this embodiment. The first electric wire 24A, the first female screw portion 25A, the first terminal unit 26A, and the second electric wire 24B, the second female screw portion 25B, and the second terminal unit 26B do not have to be arranged symmetrically with respect to the reference plane S1.

[0029] A first opening (opening) 22b is formed at a first end (first end) 22a on the base end side D2 of the joint body 22. A second opening (opening) 22d is formed at a second end (second end) 22c on the tip end side D1 of the joint body 22. The joint body 22 may be made of the same material as the piping 16, or may be made of a different material from the piping 16. For example, the electrofusion joint 21 may be a single layer of polyethylene resin and the piping 16 may be multi-layered and contain polyethylene resin, or the electrofusion joint 21 may also be multi-layered and have a different layer from the piping 16.

[0030] For example, the protrusion 23 is disposed in a middle portion (on the reference plane S1) in the direction of the axis O1 on the inner circumferential surface of the joint body 22. The protrusion 23 protrudes from the inner circumferential surface of the joint body 22 radially inward. The first electric wire 24A is formed so as to be spiral around the axis O1. The first electric wire 24A is embedded in a portion of the joint body 22 closer to the base end side D2 than the protruding portion 23. The protruding portion 23 is disposed on the opposite side (tip side D1) from the first end portion 22a than the first electric wire 24A in the direction of the axis O1.

[0031] For example, the first female thread portion 25A is formed in a cylindrical shape from metal. A female thread (reference numeral omitted) is formed on the inner circumferential surface of the first female thread portion 25A. The first female thread portion 25A is embedded in a portion of the joint body 22 (hereinafter referred to as the base-end portion of the joint body 22) that is closer to the first end 22a (base-end side D2) than the first electric wire 24A in the direction of the axis O1, so that the axis of the first female thread portion 25A is along the radial direction. Here, the base-end portion of the joint body 22 refers to a portion of the joint body 22 that does not overlap even partially with the first electric wire 24A in the direction of the axis O1. The surface of each first female thread portion 25A facing radially outward is exposed to the outside. The two first female screw portions 25A are electrically connected to both ends of the first electric wire 24A. The two first female screw portions 25A are arranged side by side with a gap between them in the circumferential direction.

[0032] The first terminal unit 26A has a first terminal (terminal) 29A and a first protective member (protective member) 30A. For example, the first terminal 29A is formed of a rod-shaped member made of metal. The first terminal 29A extends in the radial direction. A male screw (reference numeral omitted) is formed on the outer peripheral surface of the first terminal 29A. This male screw is fitted into the female screw of the first female screw portion 25A. The first terminal 29A is disposed at the base end side portion of the joint body 22. The first terminal 29A extends in the radial direction. The two first terminals 29A are attachable to and detachable from both ends of the first electric wire 24A via the first female screw portions 25A. The two first terminals 29A of the two first terminal units 26A are disposed at the base end side portion of the joint body 22.

[0033] The first protective member 30A is formed in a cylindrical shape with a bottom, and has a peripheral wall 31A and a bottom wall 32A. The peripheral wall 31A is cylindrical and disposed coaxially with the first terminal 29A. The outer diameter of the peripheral wall 31A (first protective member 30A) gradually increases as it approaches the axis O1 (moving radially inward). The inner diameter of the peripheral wall 31A is constant regardless of the radial position. The peripheral wall 31A protrudes radially outward from the joint body 22. The peripheral wall 31A surrounds the first terminal 29A. The peripheral wall may be formed in a rectangular cylindrical shape, a polygonal cylindrical shape, or the like. The bottom wall 32A is formed in an annular shape. The bottom wall 32A protrudes from a radially inner end of the peripheral wall 31A toward the first terminal 29A. The protruding tip of the peripheral wall 31A is fixed to the first terminal 29A.

[0034] The peripheral wall 31A and bottom wall 32A of the first protective member 30A configured as described above are formed of the same material as the joint body 22. Note that the peripheral wall 31A and the bottom wall 32A may be formed of a material different from that of the joint body 22. It is preferable that the two first terminal units 26A are entirely disposed in the base end portion of the joint body 22 (closer to the base end D2 than the first electric wire 24A). The two first terminal units 26A are arranged side by side with a gap between them in the circumferential direction. The two first terminal units 26A (first terminals 29A) are detachably attached to the two first female screw portions 25A.

[0035] The electrofusion joint 21 may have an indicator. The indicator has a known configuration. For example, after fusion, the indicator projects radially outward from the joint body 22, allowing the operator to confirm whether fusion has been properly performed. To make the indicator color easily visible even in a dark installation space, the color of the indicator may be different from the color of the joint body 22. The color of the indicator may be colored by coloring, printing, imprinting, etc., and the color of the indicator may be a fluorescent color, etc.

[0036] Two pipes 16 are connected to the electrofusion joint 21 configured as described above. Of the two pipes 16, the pipe 16 connected through the first opening 22b of the joint body 22 will hereinafter also be referred to as pipe 16A. Of the two pipes 16, the pipe 16 connected through the second opening 22d of the joint body 22 will hereinafter also be referred to as pipe 16B. An end portion on the tip side D1 of the pipe 16A is disposed within the joint body 22 through the first opening 22b. The joint body 22 and the pipe 16A are connected by known electric fusion. An end portion on the base side D2 of the pipe 16B is disposed within the joint body 22 through the second opening 22d. The joint body 22 and the pipe 16B are connected by known electric fusion. The outer diameter of the joint body 22 is larger than the outer diameter of the pipe 16A and the outer diameter of the pipe 16B.

[0037] Next, a method for rehabilitating the existing piping 10, in which the piping system 15 configured as above is installed in the existing piping 10, will be described. First, inlet-side vertical holes G7 and outlet-side vertical holes G8 are formed at predetermined intervals along the buried hole G6. Note that, for example, if the existing piping 10 is a sewer pipe, multiple manholes formed at predetermined intervals along the sewer pipe may be used as the inlet-side vertical holes or the outlet-side vertical holes.

[0038] 3, the outlet-side pit G8 is formed so as to include, in plan view, the end of the base end side D2 of the piping 16 located at the end of the base end side D2 of the partial piping system 15a already configured with the piping 16 and the electrofusion joint 21. In addition, an outlet-side access port 10a is formed in the pipe wall of the existing piping 10 below the outlet-side pit G8. This allows the outlet-side pit G8 to communicate with the interior of the existing piping 10 via the outlet-side access port 10a. The inlet-side vertical hole G7 is formed closer to the base end D2 than the outlet-side vertical hole G8. Also, an inlet-side access port 10b is formed in the pipe wall of the existing piping 10 below the inlet-side vertical hole G7. This allows the inlet-side vertical hole G7 to communicate with the interior of the existing piping 10 via the inlet-side access port 10b.

[0039] A plurality of pipes 16, for example, two pipes 16 and one electric fusion joint 21, are inserted into the existing pipe 10 through the inlet-side vertical hole G7 and the inlet-side working opening 10b. The length of the pipe 16 used here is a length that can be inserted into the existing pipe 10 through the inlet-side vertical hole G7 and the inlet-side working opening 10b. When inserting two pipes 16 into the existing pipe 10, it is preferable to adjust the position of the pipes 16 along the internal space of the existing pipe 10 as shown in Figure 4, and position the two pipes 16 so that the electric fusion joints 21 arranged inside the openings 22b and 22d are positioned in the center of the inlet side vertical hole G7 when viewed in a plane. Using a known support tool 100, the two pipes 16 are positioned in a state where they are engaged with the protruding portions 23 of the electric fusion joints 21 in the direction of the axis O1.

[0040] A predetermined voltage is applied to the first terminals 29A of the two first terminal units 26A of the electrofusion joint 21 by an electrofusion device (not shown), thereby electrofusion-bonding the pipe 16A to the proximal end side D2 of the joint body 22 of the electrofusion joint 21. Similarly, a predetermined voltage is applied to the second terminals 29B of the two second terminal units 26B of the electrofusion joint 21, thereby electrofusion-bonding the pipe 16B to the distal end side D1 of the joint body 22 of the electrofusion joint 21. The electrofusion joint 21 and the two pipes 16 constitute a partial piping system 15b. The two first terminal units 26A and the two second terminal units 26B are removed from the electrofusion joint 21.

[0041] The support 100 is removed from the partial piping system 15b, and the partial piping system 15b is moved to the tip side D1 inside the existing piping 10. To move the partial piping system 15b to the tip side D1, for example, a retraction device 105 shown in FIG. 5 can be used. The pulling device 105 includes a winch device 106 and a lead-in wire 107. The winch device 106 has a winding drum 106a. The winch device 106 is installed at the bottom end of the outlet-side vertical hole G8. A first end of the lead-in wire 107 is wound around the winding drum 106a, and a second end of the lead-in wire 107 is connected to an end of the tip side D1 of the pipe 16B of the partial piping system 15b. When the winch device 106 is driven to rotate the winding drum 106a in a predetermined direction, the second end of the lead-in wire 107 moves to the tip side D1. Then, inside the existing piping 10, the partial piping system 15b moves to the tip side D1.

[0042] When the pipe 16B of the partial piping system 15b approaches the pipe 16 of the partial piping system 15a, the lead-in wire 107 is removed from the pipe 16B. The lead-in device 105 is pulled up above the ground surface G2 through the outlet-side vertical hole G8.

[0043] 6, the end of pipe 16B and the end of pipe 16 are inserted into openings 22b and 22d of electrofusion joint 21. Pipes 16B and 16 are positioned using support tool 100, and pipes 16B and 16 are electrofused to electrofusion joint 21 using an electrofusion device. The two first terminal units 26A and the two second terminal units 26B are removed from the electrofusion joint 21. The support 100 is removed from the pipes 16B and 16. Through the above steps, the partial piping system 15b is connected to the partial piping system 15a, and the piping 16 of the partial piping system 15a is extended.

[0044] After this, a vertical hole is formed on the base end side D2 of the inlet-side vertical hole G7 according to the length to which the partial piping system 15a is to be extended, and the above process is repeated using this vertical hole as the inlet-side vertical hole and the inlet-side vertical hole G7 as the outlet-side vertical hole. When the work openings 10a and 10b of the existing pipe 10 are appropriately closed and the vertical holes G7 and G8 are appropriately backfilled, the existing pipe 10 is rehabilitated and the method for rehabilitating the existing pipe 10 is completed. The piping system 15 is composed of the partial piping systems 15a, 15b, etc.

[0045] As described above, in the electric fusion joint 21 of this embodiment, the two first terminals 29A can be electrically attached and detached to both ends of the first electric wire 24A. Therefore, by detaching the two first terminals 29A in advance, for example, before moving the electric fusion joint 21, it is possible to prevent damage to the two first terminals 29A when placing the electric fusion joint 21 in the existing piping 10 to rehabilitate the existing piping 10. Even when the electrofusion joint 21 is used as a joint that is not used to form a pipeline, it is possible to prevent damage to the first terminal 29A caused by external forces being applied during construction or use.

[0046] The two first terminals 29A are disposed in the fitting body 22 closer to the first end 22a than the first electric wire 24A in the direction of the axis O1. Therefore, when the pipe 16A is disposed in the fitting body 22 through the first opening 22b of the fitting body 22, as shown in FIG. 2, pressure from water (liquid) W flowing through the fitting body 22 is likely to act between the tip of the pipe 16A and the fitting body 22 (region R1), which is the upstream side where the water W tends to leak from between the fitting body 22 and the pipe 16A. On the other hand, this pressure is less likely to act on the portion of the fitting body 22 where the two first terminals 29A are disposed (region R2), which is the downstream side where the water W tends to leak from between the fitting body 22 and the pipe 16A. Therefore, leakage of the water W from the portion of the fitting body 22 where the two first terminals 29A are disposed can be prevented.

[0047] The electrofusion joint 21 includes a protrusion 23. Therefore, for example, when inserting the pipe 16 into the joint body 22, the pipe 16 can be easily positioned within the joint body 22 by abutting the pipe 16 against the protrusion 23. The outer diameter of the first protective member 30A gradually increases toward the axis O1. This allows the first protective member 30A to protect the first terminal 29A and also makes the first protective member 30A less likely to break when, for example, the first protective member 30A gets caught on the existing piping 10.

[0048] Furthermore, for example, in a small space within a building, after fusing the electric fusion joint 21 of the piping system 15 to the piping 16, the terminal units 26A, 26B can be detached from the joint body 22 (first female thread portion 25A) and then piped, thereby achieving the same effect as in this embodiment. The terminal units 26A and 26B may be removed after the piping is completed.

[0049] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to Fig. 7. The same components as those in the previous embodiment are designated by the same reference numerals, and their description will be omitted, with only the differences being described. As shown in Fig. 7, the pipe rehabilitation structure 2 of this embodiment has a piping system 40 instead of the piping system 15 in each configuration of the pipe rehabilitation structure 1 of the first embodiment. The piping system 40 has pipes 41A and 41B instead of the piping 16 in each configuration of the piping system 15.

[0050] The pipe 41A is a so-called abruptly reduced pipe, in which the diameter of the end portion is reduced relatively abruptly. The pipe 41A includes a pipe main body 42A and a reduced diameter portion 43A. The pipe body 42A is formed in a straight pipe shape. The outer diameter of the joint body 22 of the electric fusion joint 21 and the outer diameter of the pipe body 42A (piping 41A) are equal to each other. Here, "the outer diameters of A and B are equal to each other" means that the difference between the outer diameters of A and B is about several mm (for example, 3 mm). The outer diameter of the joint body 22 and the outer diameter of the pipe body 42A may be different from each other.

[0051] The reduced diameter portion 43A is formed in a cylindrical shape. The outer diameter of the reduced diameter portion 43A is smaller than the outer diameter of the pipe main body 42A. The reduced diameter portion 43A is arranged coaxially with the pipe main body 42A and protrudes from the end of the pipe main body 42A in the axial direction O1 toward the tip side D1. The reduced diameter portion 43A is the end of the pipe 41A in the axial direction O1.

[0052] The pipe body 42A and reduced diameter portion 43A of the pipe 41A are formed from the same material as the pipe 16. The reduced diameter portion 43A is disposed in the joint body 22 through the openings 22b and 22d. The joint body 22 and the pipe 41A are connected by known electrical fusion.

[0053] As described above, in the piping system 40 of this embodiment, a wider cross-sectional area for water W to pass through within the piping 41A can be ensured compared to, for example, the piping system 15 of the first embodiment, where the outer diameter of the piping 16 is smaller than the outer diameter of the fitting body 22. Furthermore, in the pipe rehabilitation structure 2 of this embodiment, the pipe rehabilitation structure can be configured using the piping system 40 that ensures a wide cross-sectional area for the water W to pass through inside the pipe 41A.

[0054] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. 8 and 9. The same components as those in the above embodiment are designated by the same reference numerals, and a description thereof will be omitted. Only the differences will be described. As shown in Fig. 8, a piping system 50 of this embodiment includes an electrofusion joint 51 of this embodiment and pipes 61A and 61B. Note that Fig. 8 shows only one each of a first female thread portion 25A, a second female thread portion 25B, a first terminal unit 52A, and a second terminal unit 52B, which will be described later.

[0055] The electrofusion joint 51 has two first terminal units 52A, two second terminal units 52B, and indicators 57A and 57B instead of the protrusion 23, two first terminal units 26A, and two second terminal units 26B of the electrofusion joint 21. Note that the electrofusion joint 51 does not necessarily have to have the indicators 57A and 57B.

[0056] In this embodiment, the two first female thread portions 25A are arranged so that the axes of the first female thread portions 25A are aligned along the axis O1. The surface of each first female thread portion 25A facing the base end side D2 is exposed to the outside. The two first female thread portions 25A are arranged side by side with a gap between them in the circumferential direction. The indicator 57A is provided on the outer circumferential surface of the joint body 22 at the base end side D2.

[0057] The first terminal unit 52A includes a first terminal 29A and a first protective member 53A. The first terminal 29A extends along the axis O1. The male thread of the first terminal 29A is fitted into the female thread of the first female screw portion 25A. The first protective member 53A is formed in a cylindrical shape with a bottom, and has a peripheral wall 54A and a bottom wall (reference numeral omitted). The peripheral wall 54A is formed in a cylindrical shape and is disposed coaxially with the first terminal 29A. The outer diameter of the peripheral wall 54A (first protective member 53A) is constant regardless of the position in the direction of the axis O1. The inner diameter of the peripheral wall 54A is constant regardless of the position in the direction of the axis O1. The peripheral wall 54A protrudes from the joint body 22 toward the base end side D2.

[0058] The bottom wall is formed in an annular shape. The bottom wall protrudes from an end of the peripheral wall 54A on the tip side D1 toward the first terminal 29A. The protruding tip of the peripheral wall is fixed to the first terminal 29A.

[0059] The pipe 61A is a so-called tapered pipe, in which the diameter of the end portion is reduced relatively gradually. The pipe 61A includes a tapered portion 62A in addition to the components of the pipe 41A. The tapered portion 62A is formed in a cylindrical shape. The tapered portion 62A is disposed between the tube main body 42A and the reduced diameter portion 43A and is disposed coaxially with the tube main body 42A and the reduced diameter portion 43A. The outer diameter and inner diameter of the tapered portion 62A each gradually decrease toward the distal end side D1. The outer diameter and inner diameter of the tapered portion 62A at the end on the base end side D2 are equal to the outer diameter and inner diameter of the tube main body 42A, and the outer diameter and inner diameter of the tapered portion 62A at the end on the tip end side D1 are equal to the outer diameter and inner diameter of the reduced diameter portion 43A, respectively. The tapered portion 62A is connected to the pipe main body 42A and the reduced diameter portion 43A.

[0060] The length of the reduced diameter portion 43A in the direction of the axis O1 is preferably less than half the length of the joint body 22 in the direction of the axis O1.

[0061] Next, a method for constructing the piping system 50 configured as above will be described. As shown in Fig. 9, when the electrofusion joint 51 and the pipes 61A and 61B are separated from each other, the reduced diameter portion 43A of the pipe 61A is placed in the first opening 22b of the electrofusion joint 51 as shown in Fig. 8. At this time, the tapered portion 62A of the pipe 61A engages with the joint body 22 of the electrofusion joint 51 from the base end side D2 of the joint body 22, so that the insertion length of the pipe 61A into the electrofusion joint 51 becomes constant. By applying a predetermined voltage to the first terminals 29A of the two first terminal units 52A of the electrofusion joint 51 using an electrofusion device not shown, the reduced diameter portion 43A of the pipe 61A is electrofused to the base end side D2 of the joint body 22 of the electrofusion joint 51. In the same manner as in the case of the pipe 61A, the reduced diameter portion 43B of the pipe 61B is electrically fused to the tip side D1 portion of the joint body 22 of the electrofusion joint 51. By carrying out the above steps, the piping system 50 is constructed.

[0062] The two first terminal units 52A and the two second terminal units 52B may be detached from the electrofusion joint 51. The piping system 50 may be placed within the existing piping 10 .

[0063] As described above, the electrofusion joint 51 and piping system 50 of this embodiment can also achieve the same effects as the electrofusion joint 21 and piping system 15 of the first embodiment. When the first terminal unit 52A protrudes from the joint body 22 toward the base end side D2, the thickness of the joint body 22 near the first electric wire 24A can be made thinner, resulting in an electric fusion joint 51 with a smaller outer diameter and a more compact size.

[0064] The inner peripheral surface of the tapered portion 62A may be curved so as to be convex in the direction between the radially inner side and the base end side D2. In this case, the piping is formed in a so-called bell-mouth shape. Compared to a suddenly contracting pipe, a gradually contracting pipe and a bell-mouth pipe can smoothly change the cross-sectional area of ​​the flow path through which the water W passes, thereby reducing the pressure loss of the water W.

[0065] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIGS. 10 and 11. The same components as those in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted. Only the differences will be described. As shown in FIG. 10, a piping system 70 of this embodiment includes a plurality of piping-equipped electrofusion joints 71 of this embodiment. The multiple pipe-attached electrofusion joints 71 are arranged side by side along the axis O1. Hereinafter, of two electrofusion joints 71 adjacent to each other in the direction of the axis O1, the electrofusion joint 71 arranged on the distal end side D1 will also be referred to as electrofusion joint 71A, and the electrofusion joint 71 arranged on the proximal end side D2 will also be referred to as electrofusion joint 71B. The configuration of electrofusion joint 71A is the same as that of electrofusion joint 71B. The configuration of electrofusion joint 71A will be described below.

[0066] The pipe-attached electrofusion joint 71A has an electrofusion part (electrofusion joint) 72 and a pipe 61A. The electric fusion section 72 includes a joint body 22, an indicator 57A, a first electric wire 24A, two first female screw portions 25A, and two first terminal units 52A. Note that Fig. 10 shows only one first female screw portion 25A and one first terminal unit 52A.

[0067] 10, the outer peripheral surface of the end portion of the base end side D2 of the joint body 22 may be inclined so as to gradually approach the axis O1 as it approaches the base end side D2. This configuration makes it easier to attach and detach the first terminal unit 26A to and from the first female screw portion 25A. The pipe 61A is disposed coaxially with the joint body 22. The end of the tip side D1 of the joint body 22 is connected to the pipe body 42A of the pipe 16A by butt welding or the like.

[0068] The reduced diameter portion 43A of the pipe 61A of the electrofusion joint 71B is disposed within the joint body 22 of the electrofusion portion 72 of the pipe-attached electrofusion joint 71A configured as described above. The joint body 22 and the reduced diameter portion 43A are connected by electrofusion.

[0069] Next, a method for constructing the piping system 70 configured as above will be described. As shown in Figure 11, with the piping-attached electrofusion joints 71A and 71B separated from each other, the reduced diameter portion 43A of the piping 61A of the electrofusion joint 71B is placed inside the joint body 22 of the electrofusion portion 72 of the piping-attached electrofusion joint 71A. By applying a predetermined voltage to the first terminals 29A of the two first terminal units 26A of the electrofusion joint 71A using an electrofusion device not shown, the reduced diameter portion 43A of the piping 61A of the electrofusion joint 71B is electrofused to the joint body 22 of the piping-attached electrofusion joint 71A.

[0070] If the piping system 70 includes three or more electrofusion joints 71, the above steps are repeated as many times as necessary.

[0071] As described above, the electrofusion joint 71 and piping system 70 of this embodiment can also achieve the same effects as the electrofusion joint 21 and piping system 15 of the first embodiment. Furthermore, the piping system 70 can be configured using only a plurality of electrofusion joints 71 with pipes. The electrofusion joint 71 may be appropriately combined with the piping 61, the electrofusion joint 51, etc. to form a piping system.

[0072] (Fifth embodiment) An embodiment of an electrofusion joint and a method for manufacturing an electrofusion joint according to the present invention will be described below with reference to FIGS. <Electric fusion joint> 12, electrofusion joint 201 has a fusion part on the inner circumferential surface of a thermoplastic resin pipe into which a connecting resin pipe (piping) is inserted. The fusion part has an electric heating wire inserted into a notched groove formed in a spiral shape on the inner circumferential surface of the resin pipe. Specifically, electrofusion joint 201 has a thermoplastic resin pipe 210, a first fusion part (fusion part) 220, two first terminals (terminals, terminals) 230, 231, a first indicator (indicator) 240, a second fusion part (fusion part) 250, two second terminals (terminals) 260, 261, and a second indicator (indicator) 270.

[0073] The thermoplastic resin pipe 210 is formed in a hollow cylindrical shape. Examples of the thermoplastic resin constituting the resin pipe 210 include polyolefin resin, polyvinyl chloride, and thermoplastic polyester (thermoplastic polyethylene terephthalate, etc.). Among them, polyolefin resin is preferred as the thermoplastic resin constituting the resin pipe 210 from the viewpoint of further improving earthquake resistance and durability. Olefin resin pipes have a higher tensile breaking elongation than rigid polyvinyl chloride pipes, measured according to JIS K 6815-1 and JIS K 6815-3. While the tensile breaking elongation of rigid polyvinyl chloride pipes is 50 to 150%, the tensile breaking elongation of olefin resin pipes is 350% or more. In particular, by the extrapolation method specified in ISO / TR9080, PE100 high-density polyethylene pipes have a tensile breaking elongation of 500% or more, which can better prevent damage caused by earthquakes. The polyolefin resin is not particularly limited, but suitable examples include polypropylene, polybutene, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, and poly-α-olefin.

[0074] The melt mass flow rate (MFR) of the thermoplastic resin is not particularly limited, but is preferably 0.1 to 25 g / 10 min, more preferably 0.1 to 10 g / 10 min, and even more preferably 0.29 to 1.00 g / 10 min., for example. MFR can be measured in accordance with JIS K 7210:1999 at a test temperature of 220°C and a test load of 10 kg.

[0075] The specific gravity of the thermoplastic resin is not particularly limited, but is, for example, 942 to 953 kg / m3. The specific heat of the thermoplastic resin is not particularly limited, but is, for example, 1.9 to 2.3 kJ / kg·[K]. The thermal conductivity of the thermoplastic resin is not particularly limited, but is, for example, 0.46 to 0.5 W / m·K.

[0076] The thermoplastic resin may be a composition containing additives such as pigments, ultraviolet absorbers, antioxidants, and lubricants.

[0077] The melting point of the thermoplastic resin (ie, the melting temperature of the resin pipe 210) is not particularly limited, but is preferably 125 to 260°C, and more preferably 125 to 150°C.

[0078] The resin pipe 210 may have a multilayer structure having a surface layer on at least one of the outer and inner surfaces. For example, by having a surface layer containing an ethylene-vinyl alcohol copolymer resin, the resin pipe 210 is more suitable for use in air conditioning, hot water supply, gas, or fuel. This is because the surface layer containing an ethylene-vinyl alcohol copolymer resin makes it less permeable to gases such as hydrogen, oxygen, propane, and butane, and hydrocarbons such as gasoline and benzene. The surface layer may contain, for example, at least one of inorganic fibers and organic fibers. Examples of inorganic fibers include glass fibers, carbon fibers, silicon-titanium-carbon composite fibers, boron fibers, and metal fibers. Examples of organic fibers include aramid fibers, vinylon fibers, polyester fibers, and polyamide fibers. When the surface layer contains these fibers, the tensile strength of the resin pipe 210 can be increased and thermal expansion can be further suppressed. The surface layer may also contain a fluororesin. When the surface layer contains fluorine, resistance (chemical resistance) to acids, alkalis, and the like can be improved. Furthermore, a layer similar to the surface layer may be provided inside the wall of the resin pipe 210 .

[0079] The thermoplastic resin pipe 210 has a first resin pipe section 211, a second resin pipe section 212, and a third resin pipe section 213. The first resin pipe section 211, the second resin pipe section 212, and the third resin pipe section 213 are arranged along the pipe axis O6 direction of the resin pipe 210. Hereinafter, the pipe axis O6 direction of the resin pipe 210 may be abbreviated as the "pipe axis O6 direction." Furthermore, the radial direction relative to the pipe axis O6 may be abbreviated as the "radial direction." Furthermore, the circumferential direction relative to the pipe axis O6 may be abbreviated as the "circumferential direction."

[0080] The first resin pipe portion 211 is provided on one end side of the electric fusion joint 201 in the direction of the pipe axis O6. The second resin pipe portion 212 is provided on the other end side of the electric fusion joint 201 in the direction of the pipe axis O6. The first resin pipe portion 211 is formed to have a larger diameter than the second resin pipe portion 212. The first resin pipe portion 211 and the second resin pipe portion 212 are arranged at one end and the other end side along the direction of the pipe axis O6 with a gap between them, and are connected by a third resin pipe portion 213. The third resin pipe portion 213 is formed in an inclined shape so that the diameter gradually decreases from the first resin pipe portion 211 toward the second resin pipe portion 212.

[0081] A first resin pipe 280 as a connecting resin pipe is inserted into the first resin pipe section 211 from one end side in the pipe axis O6 direction. A second resin pipe 281 as a connecting resin pipe is inserted into the second resin pipe section 212 from the other end side in the pipe axis O6 direction. Both the first resin pipe section 211 and the second resin pipe section 212 function as socket sections.

[0082] However, the resin pipe 210 is not limited to the above-mentioned forms (so-called increasers and reducers). For example, the outer diameter of the resin pipe 210 may be constant, and the resin pipe 210 may be a so-called socket. For example, the resin pipe 210 may be bent at the center in the pipe axis O6 direction, and the resin pipe 210 may be a so-called elbow. For example, the resin pipe 210 may have a branch pipe, and the resin pipe 210 may be a so-called tee. For example, the resin pipe 210 may be long enough to be usable not only as a simple joint but also as a general pipe material. An example of such a resin pipe 210 is a pipe material in which only the pipe end is expanded in diameter. More specifically, an example is a pipe material in which one end is a socket that is expanded in diameter and provided with a first fusion portion 220, and the other end is a spigot that is inserted into the spigot of another pipe material, and the distance between the socket and the spigot (between one end and the other end) is a long resin pipe, for example, 2 meters or more.

[0083] A first fusion portion 220 is provided on the inner circumferential surface 211a of the first resin pipe portion 211. That is, the first fusion portion 220 is provided on one end side in the pipe axis O6 direction of the electric fusion joint 201. In the first fusion portion 220, a first heating wire (heating wire, electric wire) 221 is inserted into a first notched groove (notched groove) formed in a spiral shape on the inner circumferential surface 211a of the first resin pipe portion 211. The opening portion of the first notched groove that opens on the inner circumferential surface 211a of the first resin pipe portion 211 may, for example, have a spiral shape with the pipe axis O6 as the central axis and the distance from the central axis to the inner circumferential surface 211a as the radius.

[0084] The two first terminals 230, 231 are provided in the first resin pipe section 211 near the end 211b of the socket section, spaced apart in the circumferential direction (see FIG. 13). The first terminal 230 is disposed in the first wire outlet hole 233 and connected to one end of the first heating wire 221. The first terminal 231 is disposed in the first wire outlet hole 234 and connected to the other end of the first heating wire 221. The two first wire outlet holes 233, 234 extend radially through the first resin pipe section 211 near the end 211b of the socket section. The two first terminals 230, 231 pass current through the first heating wire 221 when electrically fusing the first resin pipe 280 to the first fusion section 220.

[0085] The first indicator 240 is embedded in, for example, a first recess 241 provided in the outer circumferential surface 211c of the first resin pipe portion 11. The first indicator 240 protrudes radially outward from the first recess 241 during electrical fusion when power is supplied to the first heating wire 221 via the two first terminals 230, 231. The protrusion of the first indicator 240 makes it possible to confirm that the first fusion portion 220 has been electrically fused to the first resin pipe 280, which is the connecting partner. The first indicator 240 may be molded integrally with the resin pipe 210 using the same material, or may be assembled to the resin pipe 210 that is made of a different material from the resin pipe 210. When the first indicator 240 is molded integrally with the resin pipe 210 using the same material, for example, the first indicator 240 and the first recess 241 can be simultaneously post-machined in the resin pipe 210. Specifically, the first recess 2241 may be cut (bored) with a drill or the like while leaving the portion that will become the first indicator 240, so that the portion that will become the first indicator 240 remains in the first recess 241, and the first indicator 240 and the first recess 241 may be simultaneously molded in the resin pipe 210.

[0086] A second fusion part 250 is provided on the inner circumferential surface 212a of the second resin pipe section 212. That is, the second fusion part 250 is provided on the other end side in the pipe axis O6 direction of the electric fusion joint 201. The second fusion part 250 has a second heating wire (heating wire) 251 inserted into a second notched groove (notched groove) formed in a spiral shape on the inner circumferential surface 212a of the second resin pipe section 212. The opening part of the second notched groove that opens on the inner circumferential surface 212a of the second resin pipe section 212 may have a spiral shape, for example, with the pipe axis O6 as the central axis and the distance from the central axis to the inner circumferential surface 212a as the radius.

[0087] The second fused part 250 is configured in substantially the same manner as the first fused part 220 . There are no particular limitations on the winding direction of the spiral formed by first heating wire 221 and second heating wire 251. For example, if the winding direction is right-handed when viewed from the opening side of one socket part of electrofusion joint 201, it will be left-handed when viewed from the opening side of the other socket part. In other words, the winding direction will be right-handed or left-handed when viewed from the opening side of one socket part of electrofusion joint 201, and when viewed from the opening side of the other socket part, it will be opposite to the winding direction when viewed from one socket. Here, the winding direction of the first heating wire 221 as viewed from the opening side of the first resin pipe section 11 (the opening side of one of the receiving ports) (hereinafter also referred to as the first winding direction) and the winding direction of the second heating wire 251 as viewed from the opening side of the second resin pipe section 212 (the opening side of the other receiving port) (hereinafter also referred to as the second winding direction) may be the same or different. For example, the first winding direction and the second winding direction may be a common right-handed winding or a common left-handed winding. Furthermore, one of the first winding direction and the second winding direction may be a right-handed winding and the other a left-handed winding.

[0088] In the embodiment, an example will be described in which the first fusion part 220 is provided on one end side of the electro-fusion joint 201 and the second fusion part 250 is provided on the other end side of the electro-fusion joint 201, but this is not limiting. As another example, a fusion part may be provided on at least one end side of the electro-fusion joint 201. Here, when the fusion portion is only on one end (receptacle) side, the winding direction of the heating wire may be clockwise or counterclockwise when viewed from the opening side of the receptacle.

[0089] The two second terminals 260, 261 are provided in the second resin pipe section 212 near the end 212b of the socket section, spaced apart in the circumferential direction (see FIG. 14). The second terminal 260 is connected to one end of the second heating wire 251 via a second wire outlet hole 263. The second terminal 261 is connected to the other end of the second heating wire 251 via a second wire outlet hole 264. The two second wire outlet holes 263, 264 extend radially through the second resin pipe section 212 near the end 212b of the socket section. The two second terminals 260, 261 pass current through the second heating wire 251 when electrically fusing the second resin pipe 281 to the second fusion section 250. The two second terminals 260, 261 are configured substantially similarly to the two first terminals 230, 231.

[0090] The second indicator 270 is embedded in, for example, a second recess 271 provided in the outer circumferential surface 212c of the second resin pipe portion 212. The second indicator 270 protrudes radially outward from the second recess 271 during electrical fusion when power is supplied to the second heating wire 251 via the two second terminals 260, 261. The protrusion of the second indicator 270 makes it possible to confirm that the second fusion portion 250 has been electrically fused to the second resin pipe 81, which is the connecting partner. The second indicator 270 may be integrally molded from the same material as the resin pipe 210, or may be assembled to the resin pipe 210 that is made of a different material from the resin pipe 210. The second indicator 270 is configured in substantially the same manner as the first indicator 240.

[0091] As described above, the second fused portion 250 is configured substantially similarly to the first fused portion 220. Furthermore, the second terminals 260, 261 are configured substantially similarly to the first terminals 230, 231. Furthermore, the second indicator 270 is configured substantially similarly to the first indicator 240. Therefore, hereinafter, the resin tube 210, the first fused portion 220, the first terminals 230, 231, and the first indicator 240 will be described in detail, and a description of the other configurations will be omitted. In this embodiment, two fusion parts, the first fusion part 220 and the second fusion part 250, are provided, but it is also possible to provide only one of the first fusion part 220 and the second fusion part 250. In other words, the electrofusion joint 201 may be configured so that only one end can be electrofused.

[0092] <Resin pipe> 12 and 13, a plurality of first fixing marks (fixing marks) 215 are provided in a first portion of the first resin pipe portion 211 that is located closer to the end face 211d of the first resin pipe portion 211 in the pipe axis O6 direction than the first fused portion 220. In the embodiment, the first portion that is located closer to the end face 211d of the first resin pipe portion 211 will be described as the end face 211d of the first resin pipe portion 211. Also, in the embodiment, an example will be described in which four first fixing marks 215 are provided at equal intervals in the circumferential direction on the end face 211d of the first resin pipe portion 211. However, the first fixing marks 215 do not have to be provided at equal intervals.

[0093] The four first fixing marks 215 are, for example, depressions formed by contact with four first needle portions 306 provided on a first device 302 (see FIG. 17 ) described later. The four first needle portions 306 contact the end surface 211d of the first resin pipe portion 211, so that the end surface 211d of the first resin pipe portion 211 is supported by the first device 302. In the embodiment, an example in which there are four first fixing marks 215 will be described, but the number of first fixing marks 215 can be selected arbitrarily from two or more. Furthermore, the location where the first fixing mark 215 is provided is not limited to the end surface 211d of the first resin pipe portion 211. The location where the first fixing mark 215 is provided may be any first portion located on the end surface 211d side of the first resin pipe portion 211.

[0094] 12 and 14, a plurality of second fixing marks (fixing marks) 216 are provided in a first portion of the second resin pipe portion 212 that is located closer to the end face 212d of the second resin pipe portion 212 than the second fusion portion 250 in the direction of the pipe axis O6. In the embodiment, the first portion located closer to the end face 212d of the second resin pipe portion 212 will be described as the end face 212d of the second resin pipe portion 212. Also, in the embodiment, an example will be described in which four second fixing marks 216 are provided at equal intervals in the circumferential direction on the end face 212d of the second resin pipe portion 212. However, the second fixing marks 216 do not have to be provided at equal intervals.

[0095] The four second fixing marks 216 are, for example, depressions formed by contact with four second needle portions 307 provided on a first device 302 (see FIG. 17 ), which will be described later. When the four second needle portions 307 contact the end face 212d of the second resin pipe portion 212, the end face 212d of the second resin pipe portion 212 is supported by the first device 302. Therefore, the end face 211d of the first resin pipe portion 211 and the end face 212d of the second resin pipe portion 212 are supported by the first device 302. As a result, the resin pipe 210 is supported in a positioned state by the first device 302. In the embodiment, an example is described in which there are four second fixing marks 216, but the number of second fixing marks 216 can be selected from two or more. Furthermore, the location where the second fixing mark 216 is provided is not limited to the end surface 212d of the second resin pipe portion 212. The location where the second fixing mark 216 is provided may be any first portion located on the end surface 212d side of the second resin pipe portion 212.

[0096] The first fixing marks 215 and the second fixing marks 216 may be arranged circumferentially offset as shown in Figures 13 and 14, or may be arranged at the same position in the circumferential direction. Furthermore, the number of first fixing marks 215 and the number of second fixing marks 216 may be the same as shown in Figures 13 and 14, or may be different.

[0097] <Heating wire> As shown in FIGS. 12 and 15, the first heating wire 221 is inserted into a first notched groove (notched groove) formed in a spiral shape on the inner circumferential surface 211a of the first resin pipe portion 211 in the first fusion portion 220. The first heating wire 221 has an outgoing heating wire 221a, a folded-back portion 221b, and a returning heating wire 221c in the first fusion portion 220. Hereinafter, the outgoing heating wire 221a may be referred to as the "outgoing portion 221a." Furthermore, the returning heating wire 221c may be referred to as the "returning portion 221c."

[0098] The outgoing path portion 221a is drawn out from the first wire drawing hole 233 and is formed by progressing spirally in the outgoing direction from the opening side of the first resin tube portion 211 to the opening side of the second resin tube portion 212. Here, the opening side of the first resin tube portion 211 is "one opening side of the electrofusion joint 201." The opening side of the second resin tube portion 212 is "the other opening side of the electrofusion joint 201 (the opening side opposite to the one opening)." In Figures 12 and 15, the outgoing path portion 221a is indicated by a solid line.

[0099] The folded portion 221b connects the outward path portion 221a and the return path portion 221c of the first heating wire 221. The folded portion 221b is curved in a front view of the folded portion 221b seen from the inside in the radial direction of the first resin pipe portion 211.

[0100] The return path portion 221c is formed by a spiral extending from a folded-back portion 221b where the outgoing path portion 221a is folded back in a return direction opposite to the outgoing direction. The return path portion 221c extends to the first wire drawing hole 234 on the opening side of the first resin pipe portion 211. That is, the first heating wire 221 is formed by a single heating wire that includes the outgoing path portion 221a in the outgoing direction, the folded-back portion 221b, and the return path portion 221c in the opposite direction to the outgoing path portion 221a. The diameter of the first heating wire 221 is 0.2 mm or more and 1.5 mm or less.

[0101] The Young's modulus of the first heating wire 221 is, for example, 65 kN / mm2 More than 150kN / mm 2 The following is the Young's modulus of various materials: The Young's modulus of copper is 117 kN / mm 2 Among copper alloys, the Young's modulus of copper nickel 30 is 127.5 kN / mm 2 , and the Young's modulus of CuNi49 is 147.1kN / mm 2 , and the Young's modulus of copper nickel 69 is 147.1 kN / mm 2 , Young's modulus of phosphor bronze (C5102) is 110kN / mm 2 , Young's modulus of brass (C2600) is 110kN / mm 2 The Young's modulus of aluminum is 69 kN / mm 2 The Young's modulus of aluminum alloy (A2024) is 74 kN / mm 2 Other materials that may be used for the first heating wire 221 include nichrome, iron-chrome alloy, copper-nickel alloy, copper-manganese alloy, iron-nickel alloy, manganese, copper-nickel-manganese alloy, nickel-chrome alloy, and chromel.

[0102] The first heating wire 221 may be coated or uncoated. Even if the first heating wire 221 is coated, the Young's modulus of the first heating wire 221 can be considered to be substantially the same as that of an uncoated heating wire in a bare wire state. When the first heating wire 221 is coated, polyurethane, modified polyester, polyester, polyesterimide, or polyamideimide is used as the coating resin for the first heating wire 221. The heat resistance temperature of polyurethane is 130°C, that of modified polyester is 155 to 180°C, that of polyester is 155°C, that of polyesterimide is 180°C, and that of polyamideimide is 220°C. Preferably, an imide-based coating resin is used for the first heating wire 221, and more preferably, polyamideimide, which has excellent heat resistance, is used.

[0103] The Young's modulus of the first heating wire 221 can be measured by removing the folded portion 221b from the electrofusion joint 201 and using the folded portion 221b as a sample. The measurement method is based on, for example, JIS C 2532:1999. For example, the Young's modulus is measured by performing a test according to JIS Z 2241 described in "8.2.3 Tensile test" in JIS C 2532:1999.

[0104] <Terminal> In the first resin pipe portion 211, two first terminals 230, 231 are provided in two first wire drawing holes 233, 234 spaced apart in the circumferential direction near the end 211b of the socket portion. In this state, in the first heating wire 221, an end 221a1 of the outgoing path portion 221a is connected to the first terminal 230. In addition, in the first heating wire 221, an end 221c1 of the return path portion 221c is connected to the first terminal 231. Electricity can be applied to the first heating wire 221 through the two first terminals 230, 231.

[0105] In the embodiment, an example is described in which the two first terminals 230, 231 are provided at an interval in the circumferential direction of the first resin pipe portion 211, but this is not limiting. For example, the two first terminals 30, 31 may be provided at an interval in the pipe axis O direction.

[0106] <Indicator> The first indicator 240 is provided on the outer circumferential surface 211c of the first resin pipe portion 211. The circumferential position and the position in the pipe axis O6 direction of the first indicator 240 are as follows.

[0107] (Circumferential position of indicator) Reference planes X and Y are defined. The tube axis O6 passes through both planes X and Y. In other words, planes X and Y intersect at the tube axis O6. In addition to the tube axis O6, plane X passes through the midpoint in the circumferential direction of the line segment connecting the two first terminals 230, 231 in the circumferential direction. Meanwhile, plane Y passes through the first indicator 640 in addition to the tube axis O6. The first indicator 240 is disposed relative to the first terminals 230, 231 so that the angle formed by the plane X and the plane Y in the circumferential direction is ±90° or less. However, the circumferential position of the first indicator 240 is not limited to this.

[0108] (Indicator tube axis position) The first indicator 240 is disposed on the end surface 211d side of the first resin pipe section 211 in the tube axis O6 direction relative to the center of the range E1 in the tube axis O6 direction, within the range E1 in the tube axis O6 direction in which the first fused section 220 is provided. Here, the range E1 in the tube axis O6 direction refers to the range in the tube axis O6 direction that extends from one end of the first heating wire 221 in the tube axis O6 direction to the other end. The center of the range E1 refers to the midpoint of the range E1 in the tube axis O6 direction. In the embodiment, an example is described in which the first indicator 240 is disposed closer to the end face 211d of the first resin pipe section 211 than the center in the range E1 of the first fused section 220, but this is not limiting. For example, the first indicator 240 may be disposed between two first terminals in the direction of the pipe axis O6.

[0109] <Method for manufacturing electric fusion joints> Next, a method for manufacturing the electrofusion joint 201 will be described with reference to Figures 12 to 15 and 17 to 21 in addition to the flowchart of Figure 16. Note that in the method for manufacturing the electrofusion joint 201, an example of forming the first fusion portion 220 on the inner circumferential surface 211a of the first resin pipe portion 211 will be described, and a description of forming the second fusion portion 250 on the inner circumferential surface 212a of the second resin pipe portion 212 will be omitted. As shown in Figures 17 to 21, an electric fusion joint 201 is made by embedding a first heating wire 221 (see Figures 12 and 15) in a resin pipe 210 using an electric heating wire laying device 300. The electric heating wire laying device 300 includes a first device 302 and a second device 303. The first device 302 includes a first fixing unit 304 and a second fixing unit 305. The second device 303 includes a cutting unit (not shown), an electric heating wire embedding unit 310, and a leveling cutting unit (not shown).

[0110] As shown in FIG. 16, when manufacturing the electric fusion joint 201, first, in the pin position hole drilling process S11, two first wire withdrawal holes 233, 234 (see FIG. 15) are drilled in the electric fusion joint 201 (not the electric fusion joint 201 as a finished product, but a hollow cylindrical resin tube 210).

[0111] 16 and 17, in a joint setting step (first step) S12, the second fixing part 305 provided on the first device 302 is retracted relative to the first fixing part 304 to widen the gap between the first fixing part 304 and the second fixing part 305. This makes it possible to arrange the resin pipe 210 in the gap between the first fixing part 304 and the second fixing part 305. 16 and 18, the joint setting step S12 is continued, and the resin pipe 210 is placed in the space between the first fixing portion 304 and the second fixing portion 305. The resin pipe 210 is temporarily fixed in place with one end face of the placed resin pipe 210 (i.e., end face 211d of the first resin pipe portion 211) in contact with the four first needle portions 306 of the first fixing portion 304. After the resin pipe 210 is temporarily fixed, the second fixing portion 305 is moved toward the other end face of the resin pipe 210 (i.e., end face 212d of the second resin pipe portion 212) as indicated by arrow A1. In the illustrated example, the resin pipe 210 is placed horizontally, but the first device 302 may be configured so that the resin pipe 210 is placed vertically.

[0112] 16 and 19, the joint setting step S12 is continued, and the four second needle portions 307 of the second fixing portion 305 are brought into contact with the end surface 212d of the second resin pipe portion 212. As a result, in the joint setting step S12, the resin pipe 210 is fixed to the first fixing portion 304 and the second fixing portion 305 of the first device 102. In this state, the resin pipe 210 is set in the first device 302 so that it can rotate (rotate) about the pipe axis O6 as shown by arrow A2 (see FIG. 20).

[0113] In this way, in the joint setting step S12, the end face 211d of the first resin pipe section 211 of the resin pipe 210 comes into contact with (is pressed against) the first needle portion 306 of the first fixing portion 304 in the pipe axis O6 direction of the resin pipe 210. As a result, four first fixing marks 215 (see FIG. 13) are formed on the end face 211d of the first resin pipe section 211. Also, the end face 212d of the second resin pipe section 212 of the resin pipe 210 comes into contact with (is pressed against) the second needle portion 307 of the second fixing portion 305 in the pipe axis O6 direction of the resin pipe 210. As a result, four second fixing marks 216 (see FIG. 14) are formed on the end face 212d of the second resin pipe section 212.

[0114] After the resin pipe 210 is set in the first device 302, in an inner surface cutting (dimensioning) step S13, while the resin pipe 210 is rotated in the first device 302 as indicated by arrow A2, a cutting unit (not shown) is moved in the direction of the pipe axis O6, and the inner surface of the resin pipe 210 is cut with a cutting blade provided on the cutting unit. This results in the dimensioning of the inner surface of the resin pipe 210. After the dimensioning of the inner surface of the resin pipe 210 is performed, the rotation of the resin pipe 210 is stopped. After the rotation of the resin pipe 210 is stopped, in a wire drawing step (1) S14, the outgoing path portion 221a of the first heating wire 221 (specifically, the end portion 221a1 of the outgoing path portion 221a) is drawn out from the first wire drawing hole 233 shown in FIG. 15 from the pin position.

[0115] Next, as shown in FIGS. 16, 20, and 21, in a wire embedding portion cutting and embedding step (second step) S15, a first heating wire 221 is embedded in the inner circumferential surface 11a of the first resin pipe portion 211 using an electric heating wire embedding unit 310 provided in the second device 303. The electric heating wire embedding unit 310 has cutting means 311 such as a cutter, electric heating wire guiding means 312, and sealing means 313. The cutting means 311 such as a cutter forms a first notch groove in the inner circumferential surface 211a of the first resin pipe portion 211. The cutting means 311 has a through hole or the like that guides the first heating wire 221 into the first notch groove. The electric heating wire guiding means 312 guides the first heating wire 221 into the first notch groove. The heating wire guiding means 312 is arranged so that the first heating wire 221 passes through the cutting means 311 and enters the notch. The containment means 313 closes the first notch groove to contain the first heating wire 221 within the first notch groove.

[0116] 15, 20, and 21, the heating wire laying device 300 lays the first heating wire 221 on the inner surface 211a of the first resin pipe section 211. During this, the resin pipe 210 is rotated on its axis as indicated by arrow A2 by the first device 302, and the heating wire laying device 300 is moved in the direction of the pipe axis O6 from the end face 211d of the first resin pipe section 211 toward the end face 212d of the second resin pipe section 212. As a result, the cutting means 311 of the heating wire laying device 300 is used to cut a first notch groove in the inner surface 211a of the first resin pipe section 211, and the outgoing section 221a of the first heating wire 221 is inserted into the first notch groove. Next, the first notched groove is closed with the sealing means 313 and the outgoing path portion 221 a is embedded in the inner circumferential surface 211 a of the first resin pipe portion 211 .

[0117] After the outgoing path 221a is embedded in the inner surface 211a of the first resin pipe section 211, the rotation angle of the cutting means 311 is adjusted in the reverse direction, thereby folding back the outgoing path 221a and embedding the folded-back portion 221b in the inner surface 211a of the first resin pipe section 211. After the cutting means 3111 is reversed, the heating wire laying device 300 is moved in the direction of the pipe axis O6 toward the end face 211d of the first resin pipe section 211, thereby embedding the return path 221c of the first heating wire 221 in the inner surface 211a of the first resin pipe section 211, similar to the outgoing path 221a. Thus, the first heating wire 221 can be embedded in the inner surface 211a of the first resin pipe section 211 so as to form a double spiral with the outgoing path 221a and the return path 221c. As a result, the first fused portion 220 can be formed on the inner circumferential surface 211 a of the first resin pipe portion 211 .

[0118] 15 and 16, after the first fused portion 220 is formed on the inner surface 211a of the first resin tube portion 211, the rotation of the resin tube 210 is stopped in a wire drawing-out step (2) S16 from the pin position. After the rotation of the resin tube 210 is stopped, the end portion 221c1 of the return path portion 221c is drawn out from the first wire drawing-out hole 234. Next, in the resin leveling and thin film cutting process S17 for the wire-embedded portion, the resin pipe 210 is rotated on its axis as indicated by arrow A2 by the first device 302, and an embedded portion leveling unit (not shown) is moved in the direction of the pipe axis O6. As a result, the resin at the wire-embedded portion is leveled by the embedded portion leveling unit, and the resin-leveled portion is thin-cut with a cutting blade provided on the embedded portion leveling unit. By thin-cutting the resin-leveled portion, the dimensions of the inner surface 211a of the first resin pipe portion 211 in which the first heating wire 221 is embedded are determined.

[0119] After the dimensions of the inner surface 211a of the first resin pipe portion 211 are determined, in the fitting removal process S18, the second fixing portion 305 provided on the first device 302 is retracted from the resin pipe 210, and the resin pipe 210 with the first heating wire 221 embedded therein is removed from the first device 302. 12, 15, and 16, after the resin pipe 210 is removed from the first device 302, in the indicator step S19, the first indicator 240 is formed on the outer peripheral surface 211c of the first resin pipe portion 211. When the first indicator 240 is integral with the resin pipe 210, in the indicator step S19, a cylindrical drill is used to cut a recess in the outer peripheral surface 211c, leaving a protrusion that will become the first indicator 240, thereby forming the first indicator 240. When the first indicator 240 is a separate member from the resin pipe 210, the first indicator 240 can be formed by forming a through hole or a recess (a non-through recess) in the outer peripheral surface 211c and then assembling a member that will become the first indicator 240 into the through hole or recess.

[0120] After forming the first indicator 240 on the outer peripheral surface 211c of the first resin pipe portion 11, in the terminal pin positioning process S20, two first terminals 230, 231 are provided on the first resin pipe portion 211. The end portion 221a1 of the outgoing path portion 221a is connected to the first terminal 230. In addition, the end portion 221c1 of the return path portion 221c is connected to the first terminal 231. In this way, by carrying out steps S11 to S20, the electrofusion joint 201 can be manufactured, and the manufacturing method for the electrofusion joint 201 is completed.

[0121] As described above, according to the electrofusion joint 201 of the embodiment, as shown in FIGS. 12 to 14 and 19, four first fixing marks 215 are formed on the end surface 211d of the first resin pipe section 211. Furthermore, four second fixing marks 216 are formed on the end surface 212d of the second resin pipe section 212. The first fixing marks 215 and the second fixing marks 216 are formed by the first needle portion 306 and the second needle portion 307 of the first device 302 contacting the resin pipe 210 when the first fusion portion 220 is provided on the first resin pipe section 211 and the second fusion portion 250 is provided on the second resin pipe section 212. In this way, by sandwiching the resin pipe 210 with the first device 302 from the direction of the pipe axis O6, the first needle portion 306 and the second needle portion 307 of the first device 302 contact the resin pipe 210. Therefore, the resin tube 210 can be positioned with high precision by the first device 302. This allows the precision of forming the electrofusion joint 201 to be improved.

[0122] Furthermore, the first fixing mark 215 is provided on the end surface 211d of the first resin pipe portion 211. Furthermore, the second fixing mark 216 is provided on the end surface 212d of the second resin pipe portion 212. As a result, when the resin pipe 210 is positioned by the first device 302, the first resin pipe portion 211 is provided with the first fusion portion 220, and there is no risk that the first device 302 will interfere with the wire-embedding portion cutting and embedding process in which the second resin pipe portion 212 is provided with the second fusion portion 250.

[0123] 12 to 14 and 19, according to the manufacturing method of the electrofusion joint 201 of the embodiment, the first needle portion 306 of the first device 302 comes into contact with the end surface 211d of the first resin pipe portion 211, thereby forming four first fixing marks 215 on the end surface 211d of the first resin pipe portion 211. The second needle portion 307 of the second device 303 comes into contact with the end surface 212d of the second resin pipe portion 212, thereby forming four second fixing marks 216 on the end surface 212d of the second resin pipe portion 212. This allows the resin pipe 210 to be positioned with high precision by the first device 302. This allows for improved molding precision of the electrofusion joint 201.

[0124] Furthermore, four first fixing marks 215 are provided on the end surface 211d of the first resin pipe portion 211. Furthermore, four second fixing marks 216 are provided on the end surface 212d of the second resin pipe portion 212. As a result, with the resin pipe 210 positioned by the first device 302, there is no risk that the first device 302 will interfere with the wire embedding portion cutting and embedding process S15, in which the first heating wire 221 is inserted into the first notch groove using the second device 303.

[0125] 15, the first heating wire 221 is folded back at a folding back portion 221b to switch the spiral direction from the forward direction (i.e., forward portion 221a) to the backward direction (i.e., backward portion 221c). It is preferable that the folding back portion 221b ensures folding accuracy of the first heating wire 221, taking into consideration, for example, the pitch P1 of the heating wire 221 in the direction of the tube axis O6. Therefore, the Young's modulus of the first heating wire 221 is set to 150 kN / mm 2 Therefore, the rigidity of the heating wire can be suitably kept low. This ensures the folding accuracy of the folded-back portion 221b, and improves the forming accuracy of the electric fusion joint 201.

[0126] Furthermore, if the rigidity of the first heating wire 221 is too low, the first heating wire 221 may break when the first heating wire 221 is folded back. Therefore, the Young's modulus of the first heating wire 221 is set to 65 kN / mm 2 As a result, when the first heating wire 221 is folded back, the first heating wire 221 can be prevented from breaking at the folded back portion 221b.

[0127] Furthermore, by setting the diameter of the first heating wire 221 to be 0.2 mm or more and 1.5 mm or less, when the first heating wire 221 is folded back, the folding back accuracy of the first heating wire 221 can be ensured and breakage of the first heating wire 221 can be prevented.

[0128] In addition, by folding back the folded-back portion 221b of the first heating wire 221 in a curved shape, the first heating wire 221 can be folded back smoothly at the folded-back portion 221b, making the first heating wire 221 less likely to break.

[0129] 12 and 15, the first indicator 240 is embedded in a first recess 241 provided in the outer peripheral surface 112c of the first resin pipe section 211, for example. The first indicator 240 protrudes radially outward from the first recess 241 during electrofusion when power is supplied to the first heating wire 221 via the two first terminals 230, 231. The protrusion of the first indicator 240 makes it possible to confirm that the electrofusion joint 201 has been electrofused to the first resin pipe 280, which is the connecting partner.

[0130] Here, it is considered that during electrical fusion, the central portion 211e of the first fusion portion 220 in the direction of the tube axis O6 of the first resin pipe portion 211 will expand relatively significantly radially outward. Therefore, for example, if the first indicator 240 is provided at the center of the first fusion portion 220 on the outer circumferential surface 211c of the first resin pipe portion 211, it is considered that resin leakage will occur during fusion, or the first indicator 240 will protrude too much during fusion. For this reason, it is desirable to provide the first indicator 240 on the outer circumferential surface 211c of the first resin pipe portion 211 while ensuring the performance of the electrofusion joint 201.

[0131] Therefore, the first indicator 240 is arranged in the direction of the pipe axis O6 closer to the end face 211d of the first resin pipe section 211 than the center of the range E1 in the direction of the pipe axis O6 in which the first fusion section 220 is provided. Therefore, the first indicator 240 can be used to confirm that the electrofusion joint 201 has been electrofused to the mating first resin pipe 280. This makes it possible to ensure the performance of the electrofusion joint 201 while providing the first indicator 240 to the electrofusion joint 201.

[0132] <Modification> Next, Modifications 1, 2, and 3 of the embodiment will be described with reference to Figures 22 to 29. In Modifications 1, 2, and 3, the same or similar configurations as those of electrofusion joint 201 of the embodiment will be assigned the same reference numerals, and detailed description thereof will be omitted.

[0133] <Variation 1> A first modification of the first fixing mark 215 and the second fixing mark 216 in the embodiment will be described with reference to FIGS. 22 to 24. FIG. 22 and 23, in Modification 1(1), a plurality of first fixing marks (fixing marks) 401 are provided on the outer circumferential surface (peripheral surface) 211c of the first resin pipe section 211 as first portions located closer to the end face 211d of the first resin pipe section 211 than the first fusion section 220. An example will be described in which there are four first fixing marks 401. The first fixing marks 401 are provided by contact with the first needle section 406 of the first fixing section 405. In the first modification, four first fixing marks 401 are used as an example, but the number of first fixing marks 401 can be arbitrarily selected from two or more.

[0134] In addition, in Modification 1(1), the plurality of second fixing marks (fixing marks) 402 are provided on the outer circumferential surface (peripheral surface) 212c of the second resin tube portion 212 as a first portion located closer to the end surface 212d of the second resin tube portion 212 than the second fusion portion 250. An example will be described in which there are four second fixing marks 402. The second fixing marks 402 are provided by contact with the second needle portion of the second fixing portion (not shown). In the first modification, four second fixing marks 402 are used as an example, but the number of second fixing marks 402 can be arbitrarily selected from two or more.

[0135] According to Modification 1(1) shown in Figures 22 and 23, four first fixing marks 401 are provided on the outer peripheral surface 211c of the first resin pipe section 211, and four second fixing marks 402 are provided on the outer peripheral surface 212c of the second resin pipe section 212. Therefore, by supporting the resin pipe 210 from the radially outside thereof, the resin pipe 210 can be positioned with high precision. This improves the molding precision of the electrofusion joint 201 without the first fixing portion 405 or the second fixing portion interfering with the manufacturing process of providing the first fusion portion 220 on the inner peripheral surface 211a of the first resin pipe section 211 and the second fusion portion 250 on the inner peripheral surface 212a of the second resin pipe section 212. The first fixing marks 401 and the second fixing marks 402 may be arranged circumferentially offset from each other as shown in Figures 22 and 23, or may be arranged at the same position in the circumferential direction. Furthermore, the number of first fixing marks 401 and the number of second fixing marks 402 may be the same as shown in Figures 22 and 23, or may be different.

[0136] 24, in Modification 1(2), the plurality of first fixing marks (fixing marks) 411 are formed by contact (pressing, gripping, clamping) with a first chuck (not shown). Although four first fixing marks 411 are described as an example, the number of the plurality of first fixing marks 411 can be selected arbitrarily from two or more. Furthermore, the plurality of second fixing marks (fixing marks) 412 are formed by contact with a second chuck (not shown). Although four second fixing marks 412 are described as an example, the number of the plurality of second fixing marks 412 can be selected arbitrarily from two or more.

[0137] 24, the resin pipe 210 can be positioned with high precision by supporting the resin pipe 210 with the first chuck and the second chuck from the radially outer or inner side of the resin pipe 210. This improves the molding precision of the electrofusion joint 201 without interfering with the manufacturing process of providing the first fusion portion 220 on the inner circumferential surface 211a of the first resin pipe portion 211 and the second fusion portion 250 on the inner circumferential surface 212a of the second resin pipe portion 212 with the first chuck or the second chuck. The first fixing marks 411 and the second fixing marks 412 may be arranged circumferentially offset as shown in Fig. 24, or may be arranged at the same position in the circumferential direction. Furthermore, the number of first fixing marks 411 and the number of second fixing marks 412 may be the same as shown in Fig. 24, or may be different.

[0138] <Variation 2> A second modification of the first indicator 240 and the second indicator 270 in the embodiment will be described with reference to FIGS. 25 and 26, in Modification 2, two first terminals (terminals) 421, 422 are provided on the outer peripheral surface 211c of the first resin pipe section 211. The two first terminals 421, 422 are arranged at an interval from each other in the direction of the pipe axis O6 on the outer peripheral surface 211c of the first resin pipe section 11. The two first terminals 421, 422 are connected to both ends of the first heating wire 221, respectively.

[0139] The first heating wire 221 is folded back at the folded-back portion 221b (see FIG. 15). Therefore, both ends of the first heating wire 221 are located closer to the end face 211d of the first fused portion 220 than the center of the range E1 of the first resin pipe portion 211. As a result, the two first terminals 421, 422 are located closer to the end face 211d of the first resin pipe portion 211 than the center of the range E1 of the first fused portion 220. Therefore, the first indicator (indicator) 424 is arranged between the two first terminals 421, 422 in the direction of the tube axis O6. This allows the first indicator 424 to be arranged closer to the end face 211d of the first resin tube section 211 than the center of the range E1 of the first fused section 220.

[0140] 25 and 26, it is possible to confirm with the first indicator 424 that the electrofusion joint 201 has been electrofused to the first resin tube 280 as a connecting partner. This makes it possible to ensure the performance of the electrofusion joint 201 while providing the first indicator 424 to the electrofusion joint 201.

[0141] 25, two second terminals (terminals) 431, 432 are provided on the outer circumferential surface 212c of the second resin pipe portion 212. The two second terminals 431, 432 are connected to both ends of the second heating wire 251, similar to the two first terminals 421, 422. A second indicator (indicator) 434 is disposed in the direction of the tube axis O6 between the two second terminals 431 and 432. That is, the second indicator 434 is disposed in the same manner as the first indicator 424. As a result, according to the second indicator 434 of the second modification shown in FIG. 25, the performance of the electrofusion joint 201 can be ensured while providing the second indicator 434 to the electrofusion joint 201.

[0142] The circumferential positions of the two first terminals 421, 422 do not have to coincide with each other, and the circumferential positions of the two second terminals 431, 432 do not have to coincide with each other. In other words, the two first terminals 421, 422 do not have to be arranged side by side in the tube axis O6 direction, and the two second terminals 431, 432 do not have to be arranged side by side in the tube axis O6 direction. For example, the two first terminals 421, 422 may be spaced apart from each other in the circumferential direction and also spaced apart from each other in the tube axis O6 direction. In this case, the first indicator 424 is located between the two first terminals 421, 422 in the tube axis O6 direction. For example, the two second terminals 431, 432 may be spaced apart from each other in the circumferential direction and also spaced apart from each other in the tube axis O6 direction. In this case, the second indicator 434 is located between the two second terminals 431, 432 in the tube axis O6 direction.

[0143] <Variation 3> A third modification of the folded-back portion 221b of the first heating wire 221 in the embodiment will be described with reference to FIGS. 27 to 29. FIG. 27, in Modification 3(1), the folded portion 221b1 of the first heating wire 221 has a shape including a plurality of arcs with different curvatures when viewed from the front. The folded portion 221b1 includes two arcs, a first arc Ca1 and a second arc Ca2.

[0144] The first arc Ca1 is folded back at a radius of curvature R11 in a semicircle or greater. The center of curvature C1 of the first arc Ca1 is located inside the folded-back portion 221b1. The second arc Ca2 is folded back at a radius of curvature R12. The center of curvature C2 of the second arc Ca2 is located outside the folded-back portion 221b1. In other words, the center of curvature C1 of the first arc Ca1 and the center of curvature C2 of the second arc Ca2 are located on opposite sides of the folded-back portion 221b1 in a front view.

[0145] According to the folded portion 221b1 of the modified example 3(1), the folded portion 221b1 has a shape including two arcs, a first arc Ca1 and a second arc Ca2, which have different curvatures. This allows the first heating wire 221 to be folded smoothly at the folded portion 221b1, making the first heating wire 221 less likely to break.

[0146] Furthermore, the center of curvature C1 of the first arc Ca1 and the center of curvature C2 of the second arc Ca2 are located on opposite sides of the turn-back portion 221b1 in a front view. Therefore, the return path portion 221c, which is turned back at the turn-back portion 221b1, can be brought closer to the outgoing path portion 221a in the direction of the tube axis O6. This allows the turn-back portion 221b1 to turn the outgoing path portion 221a back onto the return path portion 221c without changing the pitch P1 between the outgoing path portion 221a and the return path portion 221c.

[0147] 28, in Modification 3(2), the folded portion 221b2 of the first heating wire 221 has a shape including a plurality of arcs with different curvatures when viewed from the front. The folded portion 221b2 has four arcs, namely, a first arc Ca3, a second arc Ca4, a third arc Ca5, and a fourth arc Ca6.

[0148] The first arc Ca3, the second arc Ca4, and the third arc Ca5 fold back the convex corners of the folded portion 221b2 to form rounded corners. The center of curvature C3 of the first arc Ca3, the center of curvature C4 of the second arc Ca4, and the center of curvature C5 of the third arc Ca5 are located inside the folded portion 221b2. The fourth arc Ca6 is folded back with a curvature radius R16. The center of curvature C6 of the fourth arc Ca6 is located outside the folded portion 221b2. In other words, the center of curvature C3 of the first arc Ca3, the center of curvature C4 of the second arc Ca4, and the center of curvature C5 of the third arc Ca5 are located on opposite sides of the folded portion 221b2 in a front view.

[0149] According to the folded portion 221b2 of the modified example 3(2), the folded portion 221b2 has a shape including four arcs, a first arc Ca3, a second arc Ca4, a third arc Ca5, and a fourth arc Ca6, each having a different curvature, which allows the first heating wire 221 to be folded smoothly at the folded portion 221b2, making the first heating wire 221 less likely to break.

[0150] Furthermore, the centers of curvature C3 of the first arc Ca3, C4 of the second arc Ca4, and C5 of the third arc Ca5 are located on opposite sides of the turn-back portion 221b2 in a front view from the center of curvature C6 of the fourth arc Ca6. Therefore, the return path portion 221c, which is turned back at the turn-back portion 221b2, can be brought closer to the outgoing path portion 221a in the direction of the tube axis O6. This allows the turn-back portion 221b2 to turn back the outgoing path portion 221a onto the return path portion 221c without changing the pitch P1 between the outgoing path portion 221a and the return path portion 221c.

[0151] As shown in Fig. 29, in Modification 3(3), the folded portion 221b3 of the first heating wire 221 has a shape including multiple arcs with different curvatures when viewed from the front. The folded portion 221b3 has two arcs, a first arc Ca7 and a second arc Ca8. The first arc Ca7 is folded with a curvature radius R17. The center of curvature C7 of the first arc Ca7 is located inside the folded portion 221b3. The second arc Ca8 is folded with a curvature radius R18. The center of curvature C8 of the second arc Ca8 is located inside the folded portion 221b3.

[0152] Here, the connecting end (end) 221a2 of the outgoing path portion 221a and the connecting end (end) 221c2 of the return path portion 221c both form a straight line inclined with respect to the tube axis O6 direction in a front view. The connecting end 221a2 is connected to the folded-back portion 221b3. The connecting end 221c2 is connected to the folded-back portion 221b3. Furthermore, the inclination angle θ1 that the connecting end 221a2 of the outgoing path portion 221a makes with respect to the tube axis O6 direction is different from the inclination angle θ2 that the connecting end 221c2 of the return path portion 221c makes with respect to the tube axis O6 direction. However, the inclination angle θ1 and the inclination angle θ2 may be the same. The inclination angle θ1 of the connecting end 221a2 with respect to the tube axis O6 indicates the angle of the connecting end 221a2 with respect to the imaginary line L6 perpendicular to the tube axis O6. The inclination angle θ2 of the connecting end 221c2 with respect to the tube axis O6 indicates the angle of the connecting end 221c2 with respect to the imaginary line L6 perpendicular to the tube axis O6.

[0153] According to the folded portion 221b3 of the modified example 3(3), the folded portion 221b3 has a shape including two arcs, a first arc Ca7 and a second arc Ca8, which have different curvatures. This allows the first heating wire 221 to be folded smoothly at the folded portion 221b3, making the first heating wire 221 less likely to break. Furthermore, the inclination angle θ1 that the connecting end 221a2 of the outgoing path portion 221a makes with respect to the tube axis O6 direction is different from the inclination angle θ2 that the connecting end 221c2 of the return path portion 221c makes with respect to the tube axis O6 direction. Therefore, the return path portion 221c that is folded back at the folded back portion 221b3 can be brought closer to the outgoing path portion 221a in the tube axis O6 direction. As a result, the folded back portion 221b3 can fold the outgoing path portion 221a back to the return path portion 221c without changing the pitch P1 between the outgoing path portion 221a and the return path portion 221c.

[0154] The reducer portion of the resin pipe 210, which is composed of the second resin pipe portion 212 and the third resin pipe portion 213, may be manufactured using a mold 500 shown in Fig. 30. The mold 500 includes a base mold 501 and an open / close mold 506. The open / close mold 506 can move in direction X relative to the base mold 501. When the base mold 501 and the open / close mold 506 approach each other and are closed, the base mold 501 and the open / close mold 506 form a cavity S25.

[0155] For example, in Figure 12, a mother tube indicated by a two-dot chain line L11 is prepared. The mother tube is made of the same material as the resin tube 210. For example, the end of the mother tube is heated in advance, and then the end of the mother tube is inserted into the cavity S25 of the mold 500. The end of the mother tube may be heated inside the mold 500. When the end of the raw pipe is pressed against the bottom surface of the base mold 501, the second resin pipe portion 212 and the third resin pipe portion 213 are formed in the raw pipe.

[0156] In particular, when the diameter of the mother pipe is large, such as 300A or more, it may be difficult to obtain an electric fusion joint by injection molding alone. Even in this case, the shape of the reducer can be formed by post-processing using mold 500.

[0157] (Sixth embodiment) 31, in piping-attached electrofusion joint 550 of this embodiment, reduced diameter section 552 is formed on one longitudinal end side of resin tube 551, and electrofusion joint 553 is incorporated on the tip side of reduced diameter section 552. A socket opening 554 into which reduced diameter section 552 can be inserted is formed on the other longitudinal end side of resin tube 551. The resin pipe 551 is made of a polyolefin resin.

[0158] Heating wire 555 is wound around the outer circumferential surface of reduced diameter portion 552 to a predetermined width along the length of reduced diameter portion 552. A helical groove (not shown) is formed on the outer circumferential surface of reduced diameter portion 552 in the region where heating wire 555 is wound, and heating wire 555 is wound along this helical groove. On the tip side of reduced diameter portion 552, the portion around which heating wire 555 is wound is small diameter portion 552a having the same inner diameter and outer diameter. In contrast, on the base end side of reduced diameter portion 552, a sloped portion 552b is formed whose outer periphery gradually narrows to form a tapered shape. Terminals 557, 558 are formed so as to protrude from the outer peripheral surface of the socket opening 554 of the resin pipe 551. These terminals 557, 558 penetrate the socket opening 554 in the thickness direction and are formed so as to protrude slightly to the inner and outer surfaces of the socket opening 554, respectively.

[0159] Two pipe-attached electrofusion joints 550 are prepared, and the two pipe-attached electrofusion joints 550 can be joined together by inserting the reduced diameter portion 552 of one plastic pipe 551 into the socket opening 554 of the other plastic pipe 551. At the tip side of reduced diameter portion 552, the entire small diameter portion 552a is inserted into socket opening 554. However, because the base end side of reduced diameter portion 552 has sloped portion 552b, when sloped portion 552b is inserted partway into socket opening 554, reduced diameter portion 552 cannot be inserted any further. When the reduced diameter portion 552 is inserted into the socket opening 554 of the electric fusion joint with piping 550 as described above, the terminals 557 and 55 are aligned with a part of the heating wire 555 and electrically connected.

[0160] Pipe-attached electric fusion joint 550 has heating wire 555 in reduced diameter section 552, so that reduced diameter section 552 can be inserted into socket opening 554 and a fusion controller (not shown) can be connected to terminals 557 and 558. Then, by passing electricity through heating wire 555 from the controller to generate heat, two pipe-attached electric fusion joints 550 can be fusion-spliced ​​together.

[0161] (Seventh embodiment) 32, an electrofusion joint 600 with piping of this embodiment has, at one end in the longitudinal direction, a resin pipe 604 equipped with a reducer pipe 603 via a butt fusion portion 602. The inner peripheral surface of the reducer pipe 603 may be gently curved. The electric fusion joint 600 with piping further has a cylindrical electric fusion joint 605 into which the tip of the reducer tube 603 can be inserted, and a resin tube 607 fused to this electric fusion joint 605 via a butt fusion portion 606. The electric fusion joint 605 has a cylindrical resin tube body 608 into which the tip of the reducer tube 603 can be inserted, and a spiral groove (not shown) is formed on the inner surface of this resin tube body 608, and an electric heating wire (not shown) is provided along this spiral groove. The reducer pipe 603, the resin pipe 604, the resin pipe 607, and the resin pipe main body 608 are preferably made of polyolefin resin.

[0162] The butt fusion joints 602 and 606 are formed by heating the sections of the plastic pipes to be fused together with a heater to a temperature above their softening point but below their melting point, then butting them together. The butt fusion joints are formed by applying a constant pressure in the butt-joining direction to the plastic pipes, maintaining the heat for a predetermined period of time, and then cooling. Butt fusion requires specialized equipment and is performed by a limited number of contractors. However, if the necessary conditions are met in advance at a factory or other facility, the plastic pipes can be reliably fused and joined. Furthermore, for the butt fused portions 602 and 606, by cutting off the outer surface beads protruding from the outer peripheries of the resin pipes 604 and 607, it becomes easier to insert the rehabilitation pipe into the existing pipe.

[0163] The electric fusion joint 605 has a spiral groove on the inner peripheral surface of the resin pipe main body 608, and a heating wire (not shown) is provided along this spiral groove to form a heat generating portion. The resin pipe main body 608 is provided with terminals 610 and 611 equipped with terminal pins that penetrate the resin pipe main body 608 in the thickness direction.

[0164] The tip of reducer pipe 603 is inserted into resin pipe main body 608, a controller is connected to terminals 610 and 611, and the necessary power is applied to the heating wire to generate heat. After the power application is stopped and the wire is cooled, a rehabilitation pipe can be obtained in which resin pipes 604 and 607 are joined to reducer pipe 603 via electric fusion joint 605. A plurality of resin pipes 604 equipped with reducer pipes 603 and resin pipes 607 equipped with electric fusion joints 605 are prepared. The tip of the reducer pipe 603 is inserted into the electric fusion joint 605 on-site, and by sequentially adding more pipes, a rehabilitated pipeline can be formed inside the existing piping.

[0165] In this embodiment, the end of the resin tube 604 is reduced in diameter via a reducer tube 603 and connected to an electric fusion joint 605. This minimizes the pressure loss of the fluid flowing inside, making it possible to achieve a structure that makes it easy to ensure a sufficient flow rate.

[0166] (Eighth embodiment) As shown in FIG. 33, a piping system 650 of this embodiment includes a resin pipe 651 and an electric fusion joint 661. The part to be connected using electric fusion joint 661 is a resin pipe 651 having a reduced diameter section 653 and a short pipe section 654 at both ends of a pipe body 652. Reduced diameter section 653 forms a reducer pipe with a tapered tip, and short pipe section 654 is a pipe for fusion splicing having the same inner diameter.

[0167] The short pipe portions 654 of the two resin pipes 651 are arranged facing each other. Then, the short pipe portion 654 of one resin pipe 651 is inserted into one opening 662a of the electric fusion joint 661, and the short pipe portion 654 of the other resin pipe 651 is inserted into the other opening 662b. Next, a controller is connected to each of the two first terminals 663 and the two second terminals 664, and electricity is applied. This causes the first heating wire 665 and the second heating wire 666 to generate heat, allowing the resin pipe 651 to be electrically fused. The first heating wire 665 and the second heating wire 666 may be wound in a folded manner.

[0168] Although the first to eighth embodiments of the present invention have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and the present invention also includes modifications, combinations, deletions, etc. of the configurations within the scope of the gist of the present invention. Furthermore, it goes without saying that the configurations shown in each embodiment can be used in appropriate combinations. For example, in the first and second embodiments, the electrofusion joint 21 does not have to include the protrusion 23, the two first protective members 30A, and the two second protective members 30B.

[0169] In the electrofusion joint 21, 51, the two second terminal units may be arranged side by side at a distance from each other in the direction of the axis O1. In this case, the two second terminal units may be non-detachably fixed to both ends of the second electric wire 24B. In this case, the electrofusion joint 21, 51 does not include two second female screw portions 25B. The outer diameters of the first and second protection members may be equal regardless of the radial position. The number of openings that the electrofusion joint has is not limited, and may be three or more. [Explanation of symbols]

[0170] 1 Pipe rehabilitation structure 10 Existing piping 15, 40, 50, 70 piping system 16, 41A, 41B, 61A, 61B Piping 21,51 Electric fusion joint 22 Joint body 22a First end 22b 1st opening (opening) 22c 2nd end 22d 2nd opening (opening) 23 Protrusion 24A 1st wire (wire) 24B 2nd electric wire (electric wire) 29A 1st terminal (terminal) 29B 2nd terminal (terminal) 30A First protective member (protective member) 30B Second protective member (protective member) 71 Electric fusion joint with piping O1 axis

Claims

1. a coupling body having a first opening formed at a first axial end thereof; An electric wire embedded in the joint body; two terminals that are disposed in the joint body closer to the first end than the electric wire in the axial direction and are detachably attachable to both ends of the electric wire; An electrofusion joint comprising:

2. The joint body is formed in a cylindrical shape, 2. The electric fusion joint according to claim 1, further comprising: a protrusion that protrudes radially inward and is located on an inner circumferential surface of the joint body on a side opposite to the first end portion relative to the electric wire in the axial direction.

3. a protective member formed in a cylindrical shape and protruding radially outward from the joint body to surround the terminal; 3. The electric fusion joint according to claim 1, wherein the outer diameter of the protection member gradually increases toward the axis.

4. The electrofusion joint according to claim 1 or 2; a pipe having an end portion disposed within the fitting body through the first opening; Equipped with A piping system, wherein the outer diameter of the fitting body and the outer diameter of the piping are equal to each other.

5. The electrofusion joint according to claim 1 or 2; a pipe connected to the joint body so as to communicate with a second opening formed at a second end of the joint body; An electric fusion joint with piping, comprising:

6. Existing piping and The piping system according to claim 4, which is disposed within the existing piping; A pipe rehabilitation structure comprising:

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