Method for joining resin pipes, resin pipes to be joined, and joining jigs

Abstract

This invention provides a joining method that allows the axial ends of two resin pipes to be joined to a connecting pipe by heat welding without damaging the piping, as well as the resin pipes to be joined and the joining jig used therein. [Solution] The method for joining resin pipes P, P includes a sealing member placement step SA2 in which a sealing member 50 is placed in the gap between the axial ends of the resin pipes P, P so that the liquid contained inside one of the resin pipes P, P does not flow out from between their axial ends; a connecting pipe placement step SA3 in which, with the sealing member 50 placed in the gap between the axial ends of the resin pipes P, P in the sealing member placement step, a connecting pipe 10 is placed so as to cover the axial ends of the resin pipes P, P from the radially outward direction; and a heat welding step SA5 in which the connecting pipe 10 is heat-welded to the resin pipes P, P respectively.

Description

Technical Field

[0001] The present invention relates to a method for joining resin pipes by thermally welding the axial ends of two resin pipes, a resin pipe to be joined used therein, and a joining jig.

Background Art

[0002] A method for joining resin pipes by thermally welding the axial ends of two resin pipes is known. As such a method for joining resin pipes, for example, Patent Document 1 discloses a method for repairing pipes. In the method for repairing pipes disclosed in this Patent Document 1, when electrically fusion-connecting a new pipe to the end of an existing polyethylene resin pipe, a part of the polyethylene resin pipe is pressed flat and constricted to stop water in the middle of the pipe. In this state, the two pipes are joined by thermally welding with an electric fusion joint. In the method disclosed in Patent Document 1, thereafter, the constricted part of the polyethylene resin pipe is restored, and an electric fusion joint is also fused to the restored part.

[0003] The reason for stopping water in the middle of the pipe as described above is that when making an electric fusion connection to the end of a polyethylene resin pipe used in a water supply pipe, if there is moisture at the electric fusion part, the fusion interface temperature will decrease, or the moisture at the fusion part will evaporate and voids will occur at the fusion interface, etc., resulting in the inability to obtain proper fusion performance (paragraph

[0002] of Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, as disclosed in Patent Document 1, pressing a part of a pipe into a flattened shape can potentially damage the pipe. In contrast, there is a need for a joining method that allows the axial ends of two resin pipes to be joined to a connecting pipe by heat welding without damaging the pipe.

[0006] The objective of the present invention is to provide a joining method that allows the axial ends of two resin pipes to be joined to a connecting pipe by heat welding without damaging the piping, as well as the resin pipes to be joined and the joining jig used therein. [Means for solving the problem]

[0007] A method for joining resin pipes according to one embodiment of the present invention is a method for joining the axial ends of two resin pipes by heat welding. The joining method comprises: a sealing member placement step of placing a sealing member in the gap between the axial ends of the two resin pipes so that the liquid contained inside at least one of the two resin pipes does not flow out from between the axial ends of the two resin pipes; a connecting pipe placement step of placing a connecting pipe so as to cover the axial ends of the two resin pipes from the radially outward position, with the sealing member placed in the gap between the axial ends of the two resin pipes in the sealing member placement step; and a heat welding step of heat welding the connecting pipe to the two resin pipes respectively (first method).

[0008] In a configuration where the axial ends of two resin pipes are covered by connecting pipes from the radially outward direction and the connecting pipes are heat-welded to the two resin pipes, if a liquid such as water penetrates between the connecting pipe and the two resin pipes, the fusion interface temperature may decrease, or moisture may evaporate at the heat-welded area, potentially causing bubbles. In this case, it may not be possible to heat-weld the connecting pipe and the two resin pipes with sufficient strength.

[0009] In contrast, as described above, by placing a sealing member in the gap between the axial ends of the two resin pipes, the liquid contained inside at least one of the two resin pipes is prevented from flowing out of the gap, thereby preventing the liquid from entering between the connecting pipe and the two resin pipes. Therefore, the connecting pipe and the two resin pipes can be joined with sufficient strength by heat welding.

[0010] In the first method described above, in the sealing member placement step, the sealing member is placed between the axial ends of the two resin pipes, and the axial ends of the two resin pipes are brought closer together in the axial direction so as to sandwich the sealing member in the axial direction (second method).

[0011] This allows the gap at the axial ends of the two resin pipes to be sealed more reliably by the sealing member. Therefore, it is possible to more reliably prevent liquid from flowing out from the gap at the axial ends of the two resin pipes and seeping between the connecting pipe and the two resin pipes. Thus, the connecting pipe and the two resin pipes can be joined with sufficient strength by heat welding.

[0012] In the first method described above, in the sealing member placement step, the sealing member is placed on the outer circumferential surface of the axial end so as to cover the gap between the axial ends of the two resin pipes from the radially outward direction (third method).

[0013] This allows the gap at the axial ends of the two resin pipes to be sealed by the sealing member. Therefore, it is possible to prevent liquid from flowing out from the gap at the axial ends of the two resin pipes and entering between the connecting pipe and the two resin pipes. Thus, the connecting pipe and the two resin pipes can be joined with sufficient strength by heat welding.

[0014] The third method further comprises a recess-forming step in which recesses capable of accommodating the sealing member are formed on the outer circumferential surfaces of the axial ends of the two resin pipes. In the sealing member placement step, the sealing member is placed in the recess formed by the recess-forming step (fourth method).

[0015] This prevents the sealing member from interfering with the connecting pipe that radially covers the axial ends of the two resin pipes, even when the sealing member is placed on the outer circumferential surface of the axial ends of the two resin pipes. Therefore, the connecting pipe can be positioned at the joining position relative to the axial ends of the two resin pipes with respect to the axial ends of the two resin pipes, while the sealing member covers the gap between the axial ends of the two resin pipes from the radial outward direction. Thus, the connecting pipe and the two resin pipes can be easily joined by heat welding.

[0016] A resin pipe to be joined according to one embodiment of the present invention is a resin pipe whose axial end is joined to a resin pipe by heat welding with a connecting pipe located radially outward. This resin pipe to be joined has a resin pipe body and a sealing portion at the axial end of the resin pipe body, which is positioned in a state where it abuts the axial end of the resin pipe in the axial direction and is positioned in the gap between the axial end of the resin pipe and the resin pipe (first configuration).

[0017] This allows the sealing member to prevent liquid from flowing out of the gap between the axial end of the resin pipe to be joined and the axial end of the resin pipe, when the axial end of the resin pipe to be joined is abutted against the axial end of the resin pipe. Thus, it is possible to realize a resin pipe to be joined with sufficient strength by heat welding to the resin pipe.

[0018] In the first configuration described above, the sealing portion is provided on the end face of the axial end of the resin pipe body to be joined (second configuration).

[0019] This allows the sealing portion to be positioned between the axial end of the resin pipe to be joined and the axial end of the resin pipe, with the axial end of the resin pipe abutting against the axial end of the resin pipe. Thus, the sealing portion can be sandwiched axially between the axial end of the resin pipe to be joined and the axial end of the resin pipe. Consequently, the sealing member can more reliably prevent liquid from flowing out from the gap between the axial end of the resin pipe to be joined and the axial end of the resin pipe. Therefore, it is possible to realize a resin pipe to be joined with sufficient strength by heat welding to the resin pipe.

[0020] A joining jig according to one embodiment of the present invention is a joining jig used when joining the axial ends of two resin pipes by heat welding. This joining jig has a pair of gripping parts that grip the two resin pipes respectively, and a connecting part that connects the pair of gripping parts in the axial direction and can change the axial distance between the pair of gripping parts so that the pair of gripping parts are brought relatively closer together in the axial direction (third configuration).

[0021] This allows the axial ends of the two resin tubes to be brought closer together in the axial direction while being held. Therefore, a sealing member can be inserted between the axial ends of the two resin tubes using a joining jig. Consequently, the sealing member can prevent liquid from flowing out from the gap between the axial end of the resin tube to be joined and the axial end of the resin tube.

[0022] Thus, with the joining jig having the above-described configuration, it becomes possible to heat-weld the connecting pipe and the axial ends of the two resin pipes with sufficient strength. [Effects of the Invention]

[0023] The method for joining resin pipes according to an embodiment of the present invention includes a seal member arranging step of arranging a seal member in the gap between the axial end portions of two resin pipes so that the liquid accommodated inside at least one of the two resin pipes does not flow out, a connecting pipe arranging step of arranging a connecting pipe so as to cover the axial end portions of the two resin pipes from the radially outer side in a state where the seal member is arranged in the gap between the axial end portions of the two resin pipes in the seal member arranging step, and a heat welding step of heat welding the connecting pipe to each of the two resin pipes.

[0024] The resin pipe to be joined according to an embodiment of the present invention is a resin pipe to be joined in which an axial end portion is joined to the resin pipe by heat welding with a connecting pipe located radially outward. This resin pipe to be joined includes a resin pipe to be joined main body and a seal portion arranged in the gap between the axial end portion of the resin pipe to be joined main body and the axial end portion of the resin pipe in a state of being axially abutted against the axial end portion of the resin pipe.

[0025] The joining jig according to an embodiment of the present invention is a joining jig used when joining the axial end portions of two resin pipes by heat welding. This joining jig includes a pair of gripping portions that respectively grip the two resin pipes, and a connecting portion that connects the pair of gripping portions in the axial direction and is capable of changing the axial distance between the pair of gripping portions so as to relatively approach the pair of gripping portions in the axial direction.

[0026] Thereby, it is possible to prevent the liquid from flowing out of the gap so that the liquid accommodated inside at least one of the two resin pipes does not flow out, and to prevent the liquid from entering between the connecting pipe and the two resin pipes. Therefore, the connecting pipe and the two resin pipes can be joined with sufficient strength by heat welding.

Brief Description of Drawings

[0027] [Figure 1] FIG. 1 is a cross-sectional view schematically showing the configuration of a resin joint pipe joined by the method for joining resin pipes according to Embodiment 1. [Figure 2] Figure 2 illustrates the process of joining pipes together using electrofusion with a fusion splicer. [Figure 3] Figure 3 is a flowchart showing the method for joining resin pipes according to Embodiment 1. [Figure 4] Figure 4 is a schematic partial cross-sectional view showing the joining of two resin tubes. [Figure 5] Figure 5 is a schematic partial cross-sectional view showing the joining of two resin tubes. [Figure 6] Figure 6 is a schematic cross-sectional view showing the structure of a resin jointed pipe joined by the resin pipe joining method according to Embodiment 2. [Figure 7] Figure 7 is a flowchart showing the method for joining resin pipes according to Embodiment 2. [Modes for carrying out the invention]

[0028] The following describes each embodiment with reference to the drawings. In each drawing, the same parts are denoted by the same reference numerals, and the description of those parts will not be repeated. Note that the dimensions of the components in each drawing do not faithfully represent the dimensions of the actual components or the dimensional ratios of each component.

[0029] Furthermore, in the following explanation, the expressions "fix," "connect," and "attach" (hereinafter referred to as "fixing, etc.") include not only cases where components are directly fixed to each other, but also cases where they are fixed to each other via other components. In other words, in the following explanation, the expressions "fixing, etc." include both direct and indirect fixing of components to each other.

[0030] [Embodiment 1] (Resin jointed pipe) Figure 1 is a schematic cross-sectional view showing the structure of a resin jointed pipe 1 joined by the resin pipe joining method according to Embodiment 1 of the present invention. The cross-sectional view shown in Figure 1 is a cross-sectional view of the resin jointed pipe 1 cut in the axial direction. The resin jointed pipe 1 is constructed by joining two resin pipes P, P to a resin connecting pipe 10. The two resin pipes P, P are each made of a resin material such as polyethylene pipe or polypropylene pipe. Similarly, the connecting pipe 10 is also made of a resin material such as polyethylene pipe or polypropylene pipe. The two resin pipes P, P and the connecting pipe 10 may be made of materials other than polyolefin resin material.

[0031] (Connecting pipe) The connecting pipe 10 connects two resin pipes P, P. The connecting pipe 10 is an annular member made of resin, such as polyethylene. Both axial ends of the connecting pipe 10 are configured to allow the axial ends of the two resin pipes P, P to be inserted.

[0032] Furthermore, the inner surface of the connecting pipe 10 does not have any protrusions for positioning the two resin pipes P, P. This allows the connecting pipe 10 to be freely moved axially relative to the two resin pipes P, P, as will be described later. Therefore, after the axial ends of the two resin pipes P, P are brought together, the connecting pipe 10 can be moved axially so as to straddle and cover those axial ends.

[0033] The connecting pipe 10 has heating wires 20 extending in the circumferential direction inside the inner circumference of both axial ends. The heating wires 20 are arranged on the inner circumference of both axial ends of the connecting pipe 10 so as to follow the inner surface of the connecting pipe 10. The heating wires 20 arranged on the inner circumference of both axial ends of the connecting pipe 10 are electrically connected to each other. The ends of the electrically connected heating wires 20 are electrically connected to a pair of terminals 22, 22, which will be described later, and protrude radially outward from the outer surface of the connecting pipe 10.

[0034] The connecting pipe 10 has a pair of radially projecting protrusions 21, 21 on its outer surface and a pair of terminals 22, 22 located within the pair of protrusions 21, 21. The pair of protrusions 21, 21 are made of cylindrical resin and cover the pair of terminals 22, 22. Although not specifically shown, the pair of terminals 22, 22 are exposed within the pair of protrusions 21, 21. The pair of terminals 22, 22 are each electrically connected to the ends of the electrically connected heating wires 20.

[0035] With the above configuration, as shown in Figure 2, by inserting the output cables V, V of the fusion splicer W into the pair of protrusions 21, 21 as described later, the output cables V, V are electrically connected to the pair of terminals 22, 22, and current can be passed through the output cables V, V and the pair of terminals 22, 22 to the heating wire 20. Therefore, the heating wire 20 melts the inner circumferential surface of the connecting pipe 10 in which it is located, and also melts the outer circumferential surfaces of the two resin pipes P, P inserted at both axial ends of the connecting pipe 10, thereby joining the connecting pipe 10 and the two resin pipes P, P. In Figures 1 and 2, reference numeral 40 denotes the joint between the connecting pipe 10 and the two resin pipes P, P. The configuration of the fusion splicer W is the same as the conventional configuration. Therefore, a detailed explanation of the configuration of the fusion splicer W is omitted.

[0036] (Sealing material) When joining the connecting pipe 10 and the two resin pipes P,P by heat welding in this manner, if a liquid such as water penetrates between the inner surface of the connecting pipe 10 and the outer surfaces of the two resin pipes P,P, the fusion interface temperature may decrease, or the moisture may evaporate at the heat-welded area, potentially causing bubbles. In such cases, it may not be possible to heat-weld the connecting pipe 10 and the two resin pipes P,P with sufficient strength.

[0037] In contrast, in this embodiment, as shown in Figure 1, a sealing member 50 is placed in the gap between the axial ends of the two resin pipes P, P so as to block the gap between them, thereby preventing liquids such as water located inside the two resin pipes P, P from seeping through the gap between the inner surface of the connecting pipe 10 and the outer surfaces of the two resin pipes P, P.

[0038] Specifically, a sealing member 50 is placed between the axial ends of the two resin pipes P, P. The two resin pipes P, P are heat-welded to the connecting pipe 10 while the sealing member 50 is pressed axially against them. In other words, the sealing member 50 prevents liquids such as water located inside the two resin pipes P, P from entering between the inner surface of the connecting pipe 10 and the outer surfaces of the two resin pipes P, P, while the outer surfaces of the two resin pipes P, P and the inner surface of the connecting pipe 10 are heat-welded together.

[0039] Therefore, when the outer surfaces of the two resin pipes P,P and the inner surface of the connecting pipe 10 are heat-welded, it is possible to suppress a decrease in the fusion interface temperature and the generation of bubbles due to the evaporation of moisture at the heat-welded area. Consequently, the connecting pipe and the two resin pipes P,P can be joined with sufficient strength by heat welding.

[0040] The sealing member 50 is preferably made of a material that has water-sealing properties. The sealing member 50 is preferably made of a material that has heat resistance. The sealing member 50 is preferably made of a material that remains adhesive even when wet with a liquid such as water. The sealing member 50 may be made of, for example, an O-ring, a packing, a sponge, or putty. The sealing member 50 may be made of a rubber material such as EPDM or SBR. The sealing member 50 may also be made of, for example, a silicone tape.

[0041] The sealing member 50 may be fixed to at least one axial end face of the two resin pipes P, P, or it may be a separate member not fixed to the two resin pipes P, P.

[0042] (Method of joining resin pipes) Next, the method of joining the two resin pipes P, P with the connecting pipe 10 will be explained using the flowchart in Figure 3. Figure 3 is a flowchart showing the method of joining the two resin pipes P, P. Figures 4 and 5 are schematic diagrams showing the joining of the two resin pipes P, P.

[0043] When the flow shown in Figure 3 starts (START), first, in step SA1, the resin pipe P is inserted into the connecting pipe 10. Next, in step SA2, the two resin pipes P, P are positioned so that the sealing member 50 is located between the axial ends of the two resin pipes P, P, and the joining jig 60 is attached to the two resin pipes P, P as shown in Figure 4. Then, the two resin pipes P, P are brought closer together axially by the joining jig 60 so that the sealing member 50 is sandwiched in the axial direction (see the white arrow in Figure 4). The two resin pipes P, P may be brought closer together axially as shown in Figure 4, or one resin pipe P may be brought closer to the other resin pipe P axially. The configuration of the joining jig 60 will be described later.

[0044] Subsequently, as shown in Figure 5, with the two resin pipes P, P sandwiching the sealing member 50 in the axial direction, in step SA3, the connecting pipe 10 is moved axially (see the white arrow in Figure 5) to the joining position for the two resin pipes P, P. Then, in that state, the two resin pipes P, P are fixed with the joining jig 60.

[0045] Then, in step SA4, the output cables V,V of the fusion splicer W are electrically connected to the pair of terminals 22,22 of the connecting pipe 10. Subsequently, in step SA5, current is passed from the output cables V,V of the fusion splicer W to the pair of terminals 22,22 of the connecting pipe 10. As a result, the heating element 20 of the connecting pipe 10 is heated, melting the inner circumference of both axial ends of the connecting pipe 10 and the outer circumference of both axial ends of the two resin pipes P,P, allowing them to be joined.

[0046] Next, the power to the fusion splicer W is turned off (step SA6), and the output cables V,V of the fusion splicer W are disconnected from the pair of terminals 22,22 of the connecting pipe 10 (step SA7). This flow is then completed (END).

[0047] Here, step SA2 corresponds to the sealing member placement process, step SA3 corresponds to the connecting pipe placement process, and step SA5 corresponds to the heat welding process.

[0048] In the resin pipe joining method according to this embodiment, the axial ends of two resin pipes P, P are joined by heat welding. The joining method includes a sealing member placement step SA2 in which a sealing member 50 is placed in the gap between the axial ends of the two resin pipes P, P so that the liquid contained inside at least one of the two resin pipes P, P does not flow out from between their axial ends; a connecting pipe placement step SA3 in which, with the sealing member 50 placed in the gap between the axial ends of the two resin pipes P, P in the sealing member placement step SA2, a connecting pipe 10 is placed so as to cover the axial ends of the two resin pipes P, P from the radially outward direction; and a heat welding step SA5 in which the connecting pipe 10 is heat-welded to the two resin pipes P, P, respectively.

[0049] In a configuration where the axial ends of two resin pipes P, P are covered by a connecting pipe 10 from the radially outward direction, and the connecting pipe 10 is heat-welded to the two resin pipes P, P, if a liquid such as water penetrates between the connecting pipe 10 and the two resin pipes P, P, the fusion interface temperature may decrease, or moisture may evaporate at the heat-welded area, potentially causing bubbles. In this case, it may not be possible to heat-weld the connecting pipe 10 and the two resin pipes P, P with sufficient strength.

[0050] In contrast, as described above, by placing a sealing member 50 in the gap between the axial ends of the two resin pipes P, P, the liquid contained inside at least one of the two resin pipes P, P is prevented from flowing out through the gap, thereby preventing the liquid from entering between the connecting pipe 10 and the two resin pipes P, P. Therefore, the connecting pipe 10 and the two resin pipes P, P can be joined with sufficient strength by heat welding.

[0051] Furthermore, in this embodiment, in the sealing member placement step SA2, the sealing member 50 is placed between the axial ends of the two resin pipes P, P, and the axial ends of the two resin pipes P, P are brought closer together in the axial direction so as to sandwich the sealing member 50 in the axial direction.

[0052] This allows the gap at the axial ends of the two resin pipes P,P to be more reliably sealed by the sealing member 50. Therefore, it is more reliably possible to prevent liquid from flowing out from the gap at the axial ends of the two resin pipes P,P and seeping between the connecting pipe 10 and the two resin pipes P,P. Thus, the connecting pipe 10 and the two resin pipes P,P can be joined with sufficient strength by heat welding.

[0053] (Joining jig) Next, the configuration of the joining jig 60 used in the joining method described above will be explained. The joining jig 60 holds two resin pipes P, P so that their axial ends are brought closer together in the axial direction.

[0054] Specifically, as shown in Figures 4 and 5, the joining jig 60 has a pair of gripping parts 61, 61 and a connecting part 62.

[0055] The pair of gripping parts 61, 61 grip two resin pipes P, P. That is, one of the pair of gripping parts 61, 61 grips one of the two resin pipes P, P, and the other gripping part 61 grips the other resin pipe P. The gripping parts 61 are configured to be fixed to the outer surface of the resin pipes P. The configuration of the gripping parts 61 can be any configuration that can be fixed to the outer surface of the resin pipes P, such as a clamp. The joining jig 60 may have three or more gripping parts.

[0056] The connecting portion 62 connects the pair of gripping portions 61, 61 in the axial direction and allows the axial distance between the pair of gripping portions 61, 61 to be changed so that they are relatively closer together in the axial direction. The connecting portion 62 has a shaft that extends in the axial direction. The connecting portion 62 can fix the axial position of the pair of gripping portions 61, 61. Therefore, the connecting portion 62 can fix the resin pipes P, P gripped by the pair of gripping portions 61, 61 at a predetermined position in the axial direction. As a result, the joining jig 60 can hold (fix) the resin pipes P, P at the joining position.

[0057] Although not specifically shown in the figures, the shaft includes, for example, two divided shafts arranged in the axial direction, with a male threaded portion at one end of one divided shaft and a female threaded portion at the other end of the other divided shaft. The male and female threaded portions are screwed together, and when they rotate in a direction that fastens them relative to each other, the two divided shafts move toward each other, while when they rotate in a direction that releases them relative to each other, the two divided shafts move toward each other. Note that the configuration for changing the axial distance between the pair of gripping portions 61, 61 in the connecting portion 62 may be other configurations. The joining jig 60 may have multiple connecting portions.

[0058] Furthermore, as shown in Figures 4 and 5, it is preferable that the pair of gripping parts 61, 61 in the joining jig 60 be attached to the two resin pipes P, P in a position that does not interfere with the connecting pipe 10 into which the resin pipes P are inserted.

[0059] The aforementioned connecting portion 62 allows the two resin pipes P, P, gripped by the pair of gripping portions 61, 61, to be brought closer together in the axial direction, and to be held (fixed) in a state where the sealing member 50 is sandwiched between the ends of the two resin pipes P, P.

[0060] The joining jig 60 in this embodiment is a joining jig used when joining the axial ends of two resin pipes P, P by heat welding. The joining jig 60 has a pair of gripping parts 61, 61 that grip the two resin pipes P, P respectively, and a connecting part 62 that connects the pair of gripping parts 61, 61 in the axial direction and can change the axial distance between the pair of gripping parts 61, 61 so that the pair of gripping parts 61, 61 are brought relatively closer in the axial direction.

[0061] This allows the axial ends of the two resin pipes P, P to be brought closer together in the axial direction while being held. Therefore, the sealing member 50 can be inserted between the axial ends of the two resin pipes P, P using the joining jig 60. Consequently, the sealing member 50 prevents liquid from flowing out from the gap between the axial ends of the two resin pipes P, P.

[0062] Thus, the joining jig 60 having the above-described configuration makes it possible to heat-weld the connecting pipe 10 and the axial ends of the two resin pipes P, P with sufficient strength.

[0063] (Resin pipe to be joined) In the joining method described above, the resin pipe P and the sealing member 50 are included in the resin pipe to be joined (see Figure 4), whose axial ends are joined to another resin pipe P by heat welding with the connecting pipe 10. That is, the resin pipe to be joined, whose axial ends are joined to another resin pipe P via the connecting pipe 10, has a resin pipe P which is the resin pipe body to be joined, and a sealing member 50 which is positioned at the axial end of the resin pipe P as a sealing part in the gap between the axial end of the other resin pipe P and the axial end of the other resin pipe P, in a state where it is abutted in the axial direction with the axial end of the other resin pipe P.

[0064] In this embodiment, the sealing member 50 may be a separate component from the resin pipe P, or it may be provided on the end face of the axial end of the resin pipe P.

[0065] When a sealing member 50 is provided on the end face of the axial end of the resin pipe P, the sealing member 50 can be more reliably positioned between the axial end of one resin pipe P and the axial end of the other resin pipe P when the axial end of one resin pipe P is abutted against the axial end of the other resin pipe P. Therefore, the sealing member 50 can be more reliably sandwiched in the axial direction by the axial ends of the two resin pipes P, P. Consequently, the sealing member 50 can more reliably prevent liquid from flowing out from the gap between the axial ends of the two resin pipes P, P. Therefore, the two resin pipes P, P can be joined to the connecting pipe 10 with sufficient strength.

[0066] [Embodiment 2] Figure 6 is a schematic cross-sectional view showing the structure of a resin jointed pipe 101 joined by the resin pipe joining method according to Embodiment 2. The cross-sectional view shown in Figure 6 is a cross-sectional view of the resin jointed pipe 1 cut in the axial direction. The resin jointed pipe 101 is constructed by joining two resin pipes P, P to a resin connecting pipe 10. In the following, components similar to those in Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted.

[0067] (Resin jointed pipe) In the resin jointed pipe 101, a sealing member 150 is fixed so as to straddle the outer circumferential surfaces of the axial ends of the two resin pipes P, P. That is, the sealing member 150 is fixed on the outer circumferential surfaces of the axial ends of the two resin pipes P, P so as to fill the gap between the axial ends of the two resin pipes P, P. The sealing member 150 is preferably a material that can be fixed on the outer circumferential surfaces of the resin pipes P, P, such as a tape material such as silicone tape, a rubber band, or a sheet material. The sealing member 150 may have any configuration as long as it can cover the gap between the axial ends of the two resin pipes P, P from the radially outward direction of the two resin pipes P, P.

[0068] A recess 151 is provided on the outer surface of the two resin pipes P, P where the sealing member 150 is fixed. That is, the sealing member 150 is positioned within the recess 151. The recess 151 is composed of resin pipe recesses 151a formed on the outer surface of the ends of the two resin pipes P, P. By positioning the sealing member 150 within the recess 151, interference between the sealing member 150 fixed to the outer surface of the two resin pipes P, P and the connecting pipe 10 can be suppressed.

[0069] The recess 151 may be provided on the outer surface of only one of the two resin pipes P, P, or it may not be provided on the outer surface of both resin pipes P, P.

[0070] (Method of joining resin pipes) The method for joining resin pipes according to this embodiment will be explained using the flowchart in Figure 7. Figure 7 is a flowchart of the method for joining resin pipes according to Embodiment 2. Note that the same reference numerals are used for parts of the resin pipe joining method as in Embodiment 1, and their explanation is omitted.

[0071] When the flow shown in Figure 7 starts (START), first, in step SA1, the resin pipe P is inserted into the connecting pipe 10. Next, in step SB2, the axial ends of the two resin pipes P, P are butted together, and the sealing member 150 is fixed to their outer surfaces. At this time, although not specifically shown, the joining jig 60 shown in Figure 4 is attached to the two resin pipes P, P to hold (fix) the axial ends of the two resin pipes P, P in a butted position.

[0072] Then, in step SA3, the connecting pipe 10 is moved axially to position it at the joining position for the two resin pipes P, P. Then, in step SA4, the output cables V, V of the fusion splicer W are connected to the pair of terminals 22, 22 of the connecting pipe 10. Then, in step SA5, current is passed through the pair of terminals 22, 22 of the connecting pipe 10 by passing the output cables V, V of the fusion splicer W through them, melting the inner circumference of both axial ends of the connecting pipe 10 and the outer circumference of both axial ends of the two resin pipes P, P to join them.

[0073] Next, the power to the fusion splicer W is turned off (step SA6), and the output cables V,V of the fusion splicer W are disconnected from the pair of terminals 22,22 of the connecting pipe 10 (step SA7). This flow is then completed (END).

[0074] Here, step SB2 corresponds to the sealing member placement process, step SA3 corresponds to the connecting pipe placement process, and step SA5 corresponds to the heat welding process.

[0075] The resin pipe joining method of this embodiment prevents liquid from entering between the connecting pipe 10 and the two resin pipes P,P. Therefore, the connecting pipe 10 and the two resin pipes P,P can be joined with sufficient strength by heat welding.

[0076] In this embodiment, the process described ranges from inserting the resin pipe P into the connecting pipe 10 to heat-welding the resin pipe P and the connecting pipe 10, and then removing the output cables V, V from the fusion machine W. However, it is preferable that the resin pipe joining method includes a step of scraping the surface (heat-welded portion) of the resin pipe P to be inserted into the connecting pipe 10 before insertion. Furthermore, it is preferable that the joining method includes a step of surface treatment or cleaning of the scraped portion before insertion to facilitate heat welding. If scraping is not performed, sufficient heat-welding strength may not be obtained, potentially leading to pipe detachment or water leakage. In addition, it is preferable that the joining method includes a time for cooling the heat-welded portion after heat-welding the resin pipe P and the connecting pipe 10 and the energization of the heating element has ended. In this case, the heat-welded portion may be cooled using a cooling device, or it may be allowed to cool naturally.

[0077] In this embodiment, during the sealing member placement step, the sealing member 150 is placed on the outer circumferential surface of the axial ends of the two resin pipes P, P so as to cover the gap between the axial ends of the two resin pipes P, P from the radially outward direction. This allows the gap between the axial ends of the two resin pipes P, P to be sealed by the sealing member 150. Therefore, it is possible to prevent liquid from flowing out from the gap between the axial ends of the two resin pipes P, P and entering between the connecting pipe 10 and the two resin pipes P, P. Thus, the connecting pipe 10 and the two resin pipes P, P can be joined with sufficient strength by heat welding.

[0078] Furthermore, the resin pipe joining method of this embodiment further includes a recess forming step of forming a recess 151 capable of accommodating a sealing member 150 on the outer circumferential surface of the axial ends of two resin pipes P, P. Then, in the sealing member placement step, the sealing member 150 is placed in the recess 151 formed by the recess forming step.

[0079] This prevents the sealing member 150 from interfering with the connecting pipe 10, which covers the axial ends of the two resin pipes P, P radially outward, even when the sealing member 150 is placed on the outer circumferential surface of the axial ends of the two resin pipes P, P. Therefore, the connecting pipe 10 can be positioned at the joining position relative to the axial ends of the two resin pipes P, P with the sealing member 150 covering the gap between the axial ends of the two resin pipes P, P from the radial outward. Thus, the connecting pipe 10 and the two resin pipes P, P can be easily joined by heat welding.

[0080] (Other embodiments) Although embodiments of the present invention have been described above, the embodiments described above are merely examples for carrying out the present invention. Therefore, the invention is not limited to the embodiments described above, and it is possible to carry out the invention by appropriately modifying the embodiments described above without departing from the spirit of the invention.

[0081] In each of the above embodiments, sealing members 50 and 150 are provided on the end faces or outer surfaces of the axial ends of the two resin pipes P, P. However, a sealing member may also be provided on the inner surface of the connecting pipe to prevent liquid from entering the joint between the connecting pipe and the two resin pipes through the gap between the axial ends of the two resin pipes. In this case, it is preferable that the sealing member is provided so as not to interfere with the joint between the connecting pipe and the two resin pipes.

[0082] In each of the embodiments described above, the two resin pipes P, P are joined by connecting the connecting pipe 10 to the two resin pipes P, P, respectively. However, the two resin pipes may also be joined by melting them together with their axial ends butted against each other, without using a connecting pipe.

[0083] In each of the above embodiments, the connecting pipe 10 has a heating element 20 on its inner circumference. However, the connecting pipe does not have to have a heating element. The connecting pipe and the resin pipe may be heated and heat-welded together by means other than a heating element.

[0084] In each of the above embodiments, the resin pipes P, P are brought closer together axially by the joining jig 60 and fixed at the joining position. However, the resin pipes P, P may be fixed by a jig other than the joining jig.

[0085] In the above embodiment 1, the sealing member 50 is arranged on the axial end face of the resin pipe P. However, a recess may be provided on the axial end face of the resin pipe, and the sealing member may be arranged in the recess. In this case, from the viewpoint of the sealing performance of the sealing member, it is preferable that the sealing member has an axial dimension greater than the depth of the recess. [Industrial applicability]

[0086] The present invention relates to a method for joining two resin pipes by heat welding at their axial ends, the resin pipes to be joined used in the method, and a joining jig. [Explanation of symbols]

[0087] 1, 101 Resin jointed pipe 10 connecting pipes 20 heating wire 21 Protrusion 22 terminals 40 Joint part 50, 150 sealing members 151 recess 151a Resin pipe recess 60 Joining jigs 61 Gripping part 62 Connecting part P resin pipe Q Resin pipe to be joined V output cable W Fusion Splicer

Claims

1. A method for joining resin pipes, which involves joining the axial ends of two resin pipes by heat welding, A sealing member placement step involves placing a sealing member in the gap between the axial ends of the two resin pipes so that the liquid contained inside at least one of the two resin pipes does not flow out from between the axial ends of the two resin pipes. With the sealing member positioned in the gap between the axial ends of the two resin pipes in the sealing member positioning step, the connecting pipe is positioned so as to cover the axial ends of the two resin pipes from the radially outward direction, A heat welding step in which the connecting pipe is heat-welded to the two resin pipes, Having, Method for joining resin pipes.

2. In the method for joining resin pipes according to claim 1, In the sealing member placement step, the sealing member is placed between the axial ends of the two resin pipes, and the axial ends of the two resin pipes are brought closer together in the axial direction so as to sandwich the sealing member in the axial direction. Method for joining resin pipes.

3. In the method for joining resin pipes according to claim 1, In the sealing member placement step, the sealing member is placed on the outer circumferential surface of the axial end so as to cover the gap between the axial ends of the two resin pipes from the radially outward direction. Method for joining resin pipes.

4. In the method for joining resin pipes according to claim 3, The process further includes a recess forming step in which recesses capable of accommodating the sealing member are formed on the outer circumferential surface of the axial ends of the two resin pipes. In the sealing member placement step, the sealing member is placed in the recess formed by the recess forming step. Method for joining resin pipes.

5. A resin pipe to be joined, in which the axial end is joined to the resin pipe by heat welding with a connecting pipe located radially outward, The resin pipe body to be joined, A sealing portion is provided at the axial end of the resin pipe body to be joined, positioned in a manner that abuts the axial end of the resin pipe against the gap between the axial end of the resin pipe and the resin pipe, Having, Resin pipe to be joined.

6. In the resin pipe to be joined according to claim 5, The sealing portion is provided on the end face of the axial end of the resin pipe body to be joined. Resin pipe to be joined.

7. A joining jig used when joining the axial ends of two resin pipes by heat welding, A pair of gripping parts for gripping the two aforementioned resin tubes, A connecting portion that connects the pair of gripping portions in the axial direction and allows the axial distance between the pair of gripping portions to be changed so that the pair of gripping portions are brought relatively closer together in the axial direction, Having, Joining jig.

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