JP2012167768A - Electrically fusing joint for covered polyethylene tube and polyethylene tube channel using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrically fusing joint, which has superior workability when connecting covered polyethylene tubes themselves, and which can suppress the deterioration of weatherability with the falling of a coated layer or others.SOLUTION: The electrically fusing joint 10 has a joint body 12 and a thermally shrinkable tube 14 covered on the surface of the joint body 12 and is used for connecting the covered polyethylene tubes 100 themselves, Both the end openings of the joint body 12 are receiving openings 16 for receiving the tube ends of the covered polyethylene tubes 100. The thermally shrinkable tube 14 forms a covering layer for preventing the deterioration by ultraviolet or others on the surface of the joint body 12, flanges 32 are formed at both ends of the same. The flanges 32 further protrude from the opening ends of the receiving openings 16 of the joint body 12 in an axial direction, and cover gaps generated between the opening ends of the receiving openings 16 and outer layers 104 of the covered polyethylene tubes 100 when the receiving openings 16 of the joint body 12 receive the tube ends of the covered polyethylene tube 100.

Description

  The present invention relates to an electric fusion joint for coated polyethylene pipe and a coated polyethylene pipe using the same, and more particularly to an electric fusion joint for coated polyethylene pipe used for connecting, for example, coated polyethylene pipes, and a coating using the same. It relates to polyethylene pipelines.

  Conventionally, a technique for applying a coating layer to the outer peripheral surface of a polyethylene pipe in order to prevent damage to the polyethylene pipe or deterioration due to ultraviolet rays or the like is known. When connecting the coated polyethylene pipes formed in this way using a joint, it is required to coat the outer surface of the joint as well as the polyethylene pipe.

For example, in the pipe connection structure of Patent Document 1, the outer peripheral surface of the joint main body of the electric fusion joint is covered with a cover member. The cover member is formed by coupling a first cover part and a second cover that are semicylindrical to each other. An end portion of each cover portion is provided with a flange portion extending in the axial direction, and a heating wire for fusing with the tube member is embedded in the flange portion. Then, by sandwiching the joint main body between the first cover part and the second cover part, the cover parts are mechanically coupled to each other, and the flange portion (the heating wire) of each cover part is fused to the pipe member. The cover member is fixedly attached to the joint body.
JP2008-19971 [F16L 47/02]

  However, in Patent Document 1, not only the joint body is fused to the pipe member, but also the flange portion of each cover portion is fused to the pipe member, so two energization (fusion) operations are required. And it takes time and effort for the work. That is, there is a difficulty in workability.

  In order to avoid this, it is also conceivable to attach the cover member to the joint body only by mechanical coupling of the cover portions without fusing the flange portion of each cover portion to the pipe member. If it does so, a cover member will be very weak with respect to the impact from the outside, a cover member will remove | deviate and it will lead to deterioration of a weather resistance.

  Therefore, a main object of the present invention is to provide a novel electrofusion joint for a coated polyethylene pipe and a coated polyethylene pipe using the same.

  Another object of the present invention is to provide an electrofused joint for a coated polyethylene pipe and a coated polyethylene pipe using the same, which are excellent in workability and hardly cause the coating layer to fall off.

  The present invention employs the following configuration in order to solve the above problems. Note that reference numerals in parentheses, supplementary explanations, and the like indicate correspondence relationships with embodiments described later to help understanding of the present invention, and do not limit the present invention in any way.

  A first invention is an electric fusion joint for coated polyethylene pipes used for connecting coated polyethylene pipes, the joint main body having a receiving port made of polyethylene and receiving a pipe end of the coated polyethylene pipe, and the joint An electrofusion joint for a coated polyethylene pipe, comprising a heat-shrinkable tube that covers the surface of the main body, protrudes in the axial direction from the open end of the receiving port, and has a flange having an inner diameter larger than the outer diameter of the coated polyethylene pipe.

  In the first invention, the electrofusion joint (10) includes a joint body (12) and a heat-shrinkable tube (14) that covers the surface of the joint body, and connects the coated polyethylene pipes (100) to each other. Used for. For example, both end openings of the joint body serve as receptacles (16) for receiving the pipe ends of the coated polyethylene pipe. Then, for example, by removing the outer layer (104) of the portion to be joined and obtaining the fused surface (106), the tube end of the coated polyethylene pipe is inserted into the receiving port, and a current is passed through the heating wire (18). Then, electrofusion bonding is performed between the inner surface of the receiving port and the fused surface of the coated polyethylene pipe. The heat-shrinkable tube is a tube that shrinks when subjected to heat treatment, and forms a coating layer for preventing deterioration due to ultraviolet rays or the like on the surface of the joint body. At both ends of the heat-shrinkable tube, a flange portion (32) is formed that protrudes further in the axial direction from the open end of the joint body receiving port. When the end is received, a gap formed between the open end of the receiving port and the outer layer of the coated polyethylene pipe is covered.

  According to the first aspect of the present invention, weather resistance can be imparted to the entire pipe line simply by electrical fusion bonding the receiving port of the joint body and the fused surface of the coated polyethylene pipe, resulting in excellent workability.

  Moreover, since the coating layer is formed by closely attaching the heat-shrinkable tube to the surface of the joint body, the coating layer is resistant to external impacts, and the coating layer is unlikely to fall off. The possibility is suppressed.

  A second invention is dependent on the first invention, and the joint main body is a heating wire embedded in the inner surface of the receiving port, a terminal portion that protrudes from the outer surface of the receiving port and energizes the heating wire, and Protruding to the outer surface of the receiving port and having an indicator for indicating that the inner surface of the receiving port and the tube end of the coated polyethylene tube are fused, and for inserting the terminal portion and the indicator through the heat shrinkable tube The insertion hole is formed.

  In the second invention, the heating wire (18) is embedded in the inner surface of the receiving port (16) of the joint body (12). Moreover, in order to show that the terminal part (22) for energizing a heating wire and the inner surface of the receptacle and the fusion surface (106) of the coated polyethylene pipe (100) were fused to the outer surface of the receptacle. The indicator (24) is projected and formed. Further, the heat-shrinkable tube (14) is formed with insertion holes (28, 30) penetrating in the thickness direction, and certain of the insertion holes (28) have terminal portions protruding from the outer surface of the receiving port. The indicator that has been raised when the inner surface of the receiving port and the fused surface of the coated polyethylene pipe are correctly fused is inserted into the other insertion hole (30).

  A third invention is dependent on the first or second invention, wherein the joint main body is accommodated in the heat-shrinkable tube before shrinkage, and is heated in a state where the shrinkage-preventing core is inserted into the receiving port. Was shrunk and placed on the surface of the joint body.

  In the third invention, when the heat-shrinkable tube (14) is put on the surface of the joint body (12), the joint body is accommodated in the heat-shrinkable tube before shrinkage, and the joint body receives the joint (16). Insert the prevention core (40). Then, they are put in a heating furnace such as a gear oven that has been heated to a predetermined temperature at which the heat-shrinkable tube contracts, and heated for a predetermined time, thereby contracting the heat-shrinkable tube and Adhere to the outer surface. At this time, the receiving port of the joint body tends to shrink by heating in the heating furnace, but the shape and dimensions are maintained by being pressed by the shrinkage preventing core from the inner surface side.

  According to the third invention, since deformation of the shape of the receiving port of the joint body can be suppressed, it is possible to prevent the occurrence of poor bonding between the electrofusion joint and the coated polyethylene pipe.

  The fourth invention is dependent on the third invention, and the inner diameter of the collar portion is set by a ring body integrated with or attached to the shrinkage prevention core.

  In the fourth invention, when the heat-shrinkable tube (14) is put on the surface of the joint body (12), the joint body is accommodated in the heat-shrinkable tube before shrinkage, and the joint body (16) is shrunk. The prevention core (40) and the ring body (34) integrated with or attached to the shrinkage prevention core are attached. In the embodiment, the ring body is formed as a separate body from the shrinkage prevention core. The ring body is formed in a hollow ring shape having an outer diameter larger than the outer diameter of the coated polyethylene pipe (100), and is inserted into the flange portion (32) of the heat-shrinkable tube, and its axial end surface is received. It is arranged along the opening end of the mouth. And although the collar part of a heat-shrinkable tube shrink | contracts by the heating of a heating furnace, it is hold | maintained in the shape which follows the external shape of a ring body by being pressed by the ring body from the inner surface side.

  According to 4th invention, the internal diameter of the collar part of a heat contraction tube can be set to an appropriate dimension.

  According to a fifth aspect of the present invention, there is provided a coated polyethylene in which coated polyethylene pipes in which the outer peripheral surface of an inner pipe formed of polyethylene is coated with an outer layer are joined together using the electrofused joint for coated polyethylene pipes according to any one of the first to fourth aspects. The length of the pipe, the length of which the outer layer of the portion to be joined to the coated polyethylene pipe is removed, is covered by the flange portion of the heat shrinkable tube when the joint port accepts the pipe end of the coated polyethylene pipe. Set the range to the remaining outer layer of the pipe to a predetermined length that can be covered, and after fusion-bonding the coated polyethylene pipe and the electrofused joint for the coated polyethylene pipe, remove the terminal part of the joint body This is a coated polyethylene pipe that seals the insertion hole of the heat-shrinkable tube.

  In 5th invention, in order to comprise the covering polyethylene pipeline which joined the covering polyethylene pipe | tube (100) using the electrofusion joint (10), first, the outer layer of the part used for joining of a covering polyethylene pipe | tube ( 104) is removed to obtain the fused surface (106), and the pipe end is inserted into the receiving port (16) of the joint body (12). At this time, the flange portion (32) of the heat shrinkable tube (14) covers a gap formed between the open end of the receiving port and the remaining outer layer of the coated polyethylene tube. Then, an electric current is passed through the heating wire (18) to perform electrofusion bonding between the inner surface of the receiving port and the fusion surface of the coated polyethylene pipe. When the fused surface is cooled and solidified after energization, the joint body terminal portion (22) protruding outside from the insertion hole (28) of the heat-shrinkable tube is removed, and the insertion hole is sealed with waterproof tape.

  According to 5th invention, a weather resistance can be provided to the whole pipe line.

  According to the present invention, when connecting the coated polyethylene pipes using the electric fusion joint, weather resistance can be imparted to the entire pipe line by a simple operation, so that the workability is excellent.

Furthermore, since the coating layer is strong against external impact, the coating layer is unlikely to fall off.
The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

It is an illustration figure which shows a mode that the covering polyethylene pipe | tube was connected using the electric fusion joint of one Example of this invention. (A) is a perspective view which shows the covering polyethylene pipe | tube of FIG. 1, (b) is a perspective view which shows a mode that the outer layer of the part corresponded to the junction part of FIG. 1 covering polyethylene pipe | tube was removed. It is a top view which shows the electric fusion joint of FIG. It is sectional drawing which shows the electric fusion joint of FIG. It is an illustration figure which shows the heat contraction tube of the electric fusion joint of FIG. It is an illustration figure which shows a mode that a heat-fusing tube is covered on the coupling main body of FIG. It is a perspective view which shows the ring body of FIG. It is a perspective view which shows the shrinkage | contraction prevention core of FIG. It is an illustration figure which shows a mode that a heat-fusing tube is covered on the coupling main body of FIG. It is an illustration figure which shows a mode that a heat-fusing tube is covered on the coupling main body of FIG. It is a top view which shows the electric fusion joint of another Example of this invention. It is sectional drawing which shows the electric fusion joint of FIG. It is an illustration figure which shows a mode that the covering polyethylene pipe | tube was connected using the electric fusion joint of FIG.

  Referring to FIG. 1, an electrofusion joint 10 according to an embodiment of the present invention includes a joint body 12 formed of polyethylene, and is used for connecting coated polyethylene pipes 100 to each other.

  Here, prior to specific description of the electrofusion joint 10, the coated polyethylene pipe 100 will be described.

  As shown in FIG. 2A, the coated polyethylene pipe 100 includes an inner pipe (main body layer) 102 and an outer layer (covering layer) 104 that covers the outer peripheral surface of the inner pipe 102. It is a conduit.

  The inner tube 102 is a fixed tube having a predetermined length (for example, 5 m), is formed of polyethylene, and is set to a predetermined diameter and thickness. The outer layer 104 is made of, for example, soft polyethylene, and is provided with weather resistance in order to prevent the inner tube 102 from being deteriorated by ultraviolet rays or the like.

  The outer layer 104 is provided over and covers the entire outer peripheral surface of the inner tube 102, and the thickness thereof is, for example, 1.5 mm. Then, as shown in FIG. 2B, when the electric fusion joint 10 is fusion-bonded, a portion of the outer layer 104 used for bonding is removed to obtain a fusion surface 106 for good bonding. be able to.

  Since such a coated polyethylene pipe 100 can be manufactured by a conventionally known method, a detailed description of the manufacturing method is omitted. In short, it is manufactured by further coextruding the outer layer 104 to cover the outer peripheral surface of the inner tube 102 with respect to the inner tube 102 previously extruded alone.

  Returning to the description of the electrical fusion joint 10, the electrical fusion joint 10 is for connecting two coated polyethylene pipes 100 in a straight line, and the heat applied to the surface of the joint body 12 and the joint body 12. A shrink tube 14 is provided.

  As shown in FIGS. 3 and 4, the joint body 12 is formed in a cylindrical shape, for example. Both ends of the joint body 12 are openings 16 for receiving the pipe ends of the coated polyethylene pipe 100, and heating wires 18 are embedded in the inner surface thereof. The inner diameter of the receiving port 16 is 126 mm, for example. A stopper 20 that stops the pipe end of the coated polyethylene pipe 100 is formed on the inner surface of the joint body 12 behind the heating wire 18, that is, on the inner surface of the center of the joint body 12.

  The protrusion formed on the outer surface of the joint body 12 is a terminal portion 22 connected to the heating wire 18, and the inner surface of the receiving port 16 and the coated polyethylene pipe 100 are fused to the center side of the terminal portion 22. An indicator 24 is formed to indicate that the landing surface 106 has been fused. The indicator 24 is raised by the pressure of the resin melted by the heating wire 18 acting on its root, and the inner surface of the receiving port 16 and the fused surface 106 of the coated polyethylene pipe 100 can be correctly fused. It is used as a guide.

  For example, when the inner surface of the receiving port 16 and the fused surface 106 of the coated polyethylene pipe 100 are fused, the tube end of the coated polyethylene pipe 100 is inserted into the receiving port 16 of the joint body 12 until it contacts the stopper 20, Thereafter, the heating wire 18 is energized through the terminal portion 22 from the controller.

  Further, as described above, the surface of the joint body 12 is covered with the heat shrinkable tube (coating layer) 14.

  The heat-shrinkable tube 14 is a tube made of EPDM (ethylene propylene diene monomer) or the like that shrinks when subjected to heat treatment. As described in detail later, the diameter of the heat-shrinkable tube 14 before being put on the surface of the joint body 12 is set larger than the outer diameter of the joint body 12. The heat-shrinkable tube 14 is reduced in diameter by being heated in a heating furnace such as a gear oven, and is closely attached to the surface of the joint body 12 to prevent the surface of the joint body 12 from being deteriorated by ultraviolet rays or the like. Form a layer.

  The heat-shrinkable tube 14 includes a main body 26 that covers the surface of the joint main body 12 and has a thickness of 1.5 mm, for example. As shown in FIG. 5, the body 26 is formed with two insertion holes 28 and 30 that penetrate the body 26 in the thickness direction. One insertion hole 28 is formed at a position corresponding to the terminal portion 22 of the joint body 12, and the terminal portion 22 protruding from the outer surface of the joint body 12 is inserted therethrough. The other insertion hole 30 is formed at a position corresponding to the indicator 24 of the joint body 12 and is an indicator that rises when the inner surface of the receiving port 16 and the fusion surface 106 of the coated polyethylene pipe 100 are correctly fused. 24 will be inserted.

  Returning to FIG. 3 and FIG. 4, both end portions of the main body 26 protrude outward in the axial direction from the opening end of the receiving port 16 of the joint main body 12, and an annular flange 32 is formed there. The flange portion 32 is a gap formed between the open end of the receiving port 16 and the outer layer 104 of the coated polyethylene pipe 100 when the receiving port 16 of the joint body 12 receives the pipe end of the coated polyethylene tube 100 (that is, the covering). It has a length capable of covering from the upper side the range (up to the outer layer 104 remaining in the polyethylene tube 100), and in this embodiment, it is, for example, 12 mm. The axial length of the flange 32 is set corresponding to the axial length of the ring body 34 as will be described in detail later. In addition, the inner diameter of the flange portion 32 is set to be larger than the outer diameter of the coated polyethylene pipe 100 (that is, the outer diameter of the outer layer 104) corresponding to the outer diameter of the ring body 34. For example, 140 mm.

  With reference to FIGS. 6 to 10, a method of covering the surface of the joint body 12 with the heat shrinkable tube 14 will be described below.

  First, the joint body 12 is accommodated in the heat shrinkable tube 14 before shrinkage. Then, as shown in FIG. 6, the ring body 34 and the shrinkage prevention core 40 are attached to the receiving port 16 of the joint body 12.

  Here, with reference to FIG. 7, the structure of the ring body 34 is demonstrated in detail. As shown in FIG. 7, the ring body 34 is for forming the flange portion 32 of the heat-shrinkable tube 14, and is made of a material such as iron that has been quenched and formed into a hollow ring shape. 36. The length of the main body 36 in the axial direction is, for example, 12 mm, and the outer diameter thereof is, for example, 140 mm. On the inner peripheral surface of the main body 36, a convex portion 38 protruding in an annular shape is formed at one end in the axial direction. The convex portion 38 projects inward in the radial direction, and the diameter of the tip surface thereof (that is, the inner diameter of the convex portion 38) is such that the inner diameter of the receiving port 16 of the joint body 12 after heating and cooling becomes a specified value. The predetermined value is set accordingly.

  Further, the configuration of the shrinkage prevention core 40 will be described in detail with reference to FIG. As shown in FIG. 8, the shrinkage prevention core 40 is for maintaining the shape of the receiving port 16 of the joint body 12 when heat treatment is performed in a heating furnace such as a gear oven. For example, a metal such as aluminum is used. And has a main body 42 formed in a substantially hollow cylindrical shape with one end opened.

  The outer diameter of the main body 42 is set to a predetermined value so that the inner diameter of the receiving port 16 of the joint main body 12 after heating and cooling becomes a specified value, for example, 126 mm. Further, the other end of the main body 42 is expanded in a stepped shape, and a stepped portion 44 is formed there. The outer diameter of the stepped portion 44 is set substantially equal to the inner diameter of the main body 36 of the ring body 34, and is 130 mm, for example. A grip 46 is formed at the other end of the main body 40 for pulling out the anti-shrink core 40 with an air cylinder or the like when the anti-shrink core 40 is removed from the receiving port 16 of the joint main body 12. The shape of the gripping portion 46 is not particularly limited, but in this embodiment, a screw hole 48 is formed in the central portion of the other end surface of the main body 40, and the screw rod 50 is attached thereto. The threaded rod 50 is male threaded, and the male thread is screwed into the female thread of the threaded hole 48 of the main body 40 and fixed with a nut 52. A nut 54 is screwed to the tip of the screw rod 50.

  Returning to FIG. 6, when attaching the ring body 34 and the shrinkage-preventing core 40 to the receiving port 16 of the joint body 12, the ring body 34 is inserted into the flange portion 32 of the heat shrinkable tube 14, and one side ( The axial end surface of the convex portion 38 side is arranged along the opening end of the receiving port 16, and the front end surface of the convex portion 38 is arranged flush with the inner surface of the receiving port 16. The shrinkage prevention core 40 is inserted into the ring body 34 and the receiving port 16 of the joint body 12 until the stepped portion 44 is locked to the convex portion 38 of the ring body 34.

  When the attachment of the ring body 34 and the shrinkage-preventing core 40 to the receiving port 16 of the joint body 12 is finished, they are placed in a heating furnace such as a gear oven that has been heated to a predetermined temperature at which the heat-shrinkable tube 14 shrinks. And heat for a predetermined time, eg, 10-15 minutes. In addition, the insertion hole 28 is previously drilled in the main body 26 of the heat shrinkable tube 14, and the terminal portion 22 is inserted into the insertion hole 28 before heating.

  Then, the heat-shrinkable tube 14 contracts in the radial direction (that is, contracts in diameter) and comes into close contact with the outer surface of the joint body 12. At this time, the receiving port 16 of the joint body 12 tends to shrink by heating in the heating furnace, but the shape and dimensions are maintained by being held by the shrinkage preventing core 40 from the inner surface side. Further, the flange portion 32 of the heat shrinkable tube 14 is contracted by heating in the heating furnace, but is held in a shape along the outer shape of the ring body 34 by being pressed by the ring body 34 from the inner surface side.

  When the heat treatment is completed, the heat shrinkable tube 14 is appropriately cooled and solidified by passing through a cooling water tank or the like.

  Then, as shown in FIG. 9, the flange portion 32 of the heat shrinkable tube 14 is cut along the axial end surface on the other side of the main body 36, and then the ring body 34 is fixedly pressed with an air cylinder or the like. By pulling the grip 46 of the shrinkage prevention core 40, the shrinkage prevention core 40 is removed from the receiving port 16 of the joint body 12 as shown in FIG. 8.

  Finally, the ring body 34 disposed in the collar portion 32 is removed, an insertion hole 30 for inserting the indicator 24 is formed in the main body 26 of the heat shrinkable tube 14, and the operation is completed.

  Furthermore, with reference to FIG. 1, the method of comprising the coated polyethylene pipe line 200 in which the coated polyethylene pipes 100 are connected using such an electric fusion joint 10 will be described below.

  First, specifically, the coated polyethylene pipe 100 is cut into the surface of the outer layer 104 of the coated polyethylene pipe 100 using a cutter knife, a dedicated tool for removing the coated layer (not shown), or the like, and the outer layer is formed from that portion. Tear and tear 104; Then, a fused surface 106 as shown in FIG. 2B is obtained at the tube end of the coated polyethylene tube 100. Then, the fusion surface 106 is cleaned, and the pipe end portion is inserted into one receiving port 16 of the electrofusion joint 10.

  Subsequently, the outer layer 104 of the portion of the coated polyethylene pipe 100 different from that described above to be joined is removed (that is, the fused surface 106 is obtained), the fused surface 106 is cleaned, and the pipe end portion is obtained. Is inserted into the other receiving port 16 of the electric fusion joint 10.

  Next, a controller power cable (not shown) is connected to the power source, and the power source is turned on to start up. Then, the connection terminal of the output cable extending from the controller is connected to the terminal portion 22 of the electrofusion joint 10. Then, when an electric current is passed through the heating wire 18, heat is generated, and this heat melts the inner surface of the receiving port 16 and the fusion surface 106 of the coated polyethylene pipe 100 to perform electrofusion bonding. In addition, when the inner surface of the receiving port 16 and the fused surface 106 of the coated polyethylene pipe 100 are correctly fused, the indicator 24 of the joint body 12 rises, but the raised indicator 24 is inserted into the insertion hole 30. The

  After the energization, when the fusion surface is cooled and solidified, the terminal portion 22 and the indicator 24 of the electric fusion joint 10 protruding to the outside from the insertion holes 28 and 30 of the heat shrinkable tube 14 are removed with a cutter or the like. And the insertion holes 28 and 30 are sealed with waterproof tapes (not shown), such as a butyl tape, and an operation | work is complete | finished. However, when the rising degree of the indicator 24 is small, it is not always necessary to remove the indicator 24, and the insertion hole 30 together with the raised indicator 24 may be sealed with waterproof tape.

  In this embodiment, the gap formed between the open end of the receiving port 16 of the joint body 12 and the outer layer 104 of the coated polyethylene pipe 100 can be covered by the flange portion 32 of the heat shrinkable tube 14. Are connected to each other by the electric fusion joint 10, the fused surface 106 of the coated polyethylene pipe 100 is not exposed to the outside, and the fused surface 106 can be prevented from being deteriorated by ultraviolet rays or the like.

  That is, when the coated polyethylene pipe 100 is connected using the electric fusion joint 10 to form a pipe line, the receiving port 16 of the joint body 12 and the fusion surface 106 of the coated polyethylene pipe 100 are merely fusion bonded. Thus, weather resistance can be imparted to the entire pipeline. Therefore, unlike Patent Document 1, it is not necessary to perform the two energization (fusion) operations at the construction site, and the workability is improved accordingly.

  Moreover, since the coating layer is formed on the surface of the joint body 12 by bringing the heat-shrinkable tube 14 into close contact with the surface of the joint body 12, the coating layer is strong against impact from the outside, and the coating layer falls off. Therefore, it is possible to suppress the possibility of deterioration of the weather resistance due to the occurrence of the phenomenon.

  Further, since the covering layer is less likely to drop off, for example, the electrofusion joint 10 can be applied without any problem even in an environment in which the pipe line is exposed to the outside.

  Further, in this embodiment, the joint main body 12 is accommodated in the heat shrinkable tube 14, and heated in a heating furnace with the shrinkage preventing core 40 inserted into the receiving port 16, whereby the heat shrinkable tube 14 is heated. It was made to cover the surface of. Accordingly, during the heating in the heating furnace, the receiving port 16 of the joint body 12 to be thermally contracted is pressed from the inner surface side by the shrinkage preventing core 40, so that the shape and dimensions of the receiving port 16 can be maintained. It is.

  Here, if the shape of the receiving port 16 of the electrofusion joint 10 is deformed even a little, there is a risk of causing a bonding failure such that the coated polyethylene pipe 100 cannot be inserted into the receiving port 16.

  However, according to this embodiment, since the joint body 12 is heated with the shrinkage-preventing core 40 inserted into the receiving port 16, deformation of the receiving port 16 is suppressed by the shrinkage-preventing core 40. It is possible to prevent the occurrence of poor bonding between the joint fitting 10 and the coated polyethylene pipe 100.

  Furthermore, in this embodiment, the heat shrinkable tube 14 is heated in a heating furnace with the ring body 34 inserted into the flange portion 32, thereby forming the flange portion 32 in a shape along the outer shape of the ring body 34. As a result, the inner diameter of the flange 32 of the heat shrinkable tube 14 can be set to an appropriate dimension.

  In the above-mentioned embodiment, the case where the surface of the socket-type joint body 12 is covered with the heat shrinkable tube 14 is shown. However, the present invention is not limited to this, and may be a bend type, a flange type, an elbow type, or the like. The heat shrinkable tube 14 may be covered on the surface of the other type of joint body 12. However, when it is difficult to cover the entire surface of such other type of joint body 12 with a single heat shrinkable tube 14, a plurality of heat shrinkable tubes 14 are prepared, and they are adjacent to each other. Covering the surface of the joint body 12 so that the ends of the contraction tube 14 overlap each other is preferable because the entire surface of the joint body 12 can be reliably covered.

  For example, in an electrofusion joint 10 according to another embodiment of the present invention, the joint body 12 includes a curved pipe portion 56, and connects two coated polyethylene pipes 100 in a curved shape. Hereinafter, the same number is attached | subjected about the part which is common in the electric fusion joint 10 shown in FIG. 1, and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 12 and 13, the curved pipe portion 56 is formed in a curved tubular shape having a predetermined bending angle (11.25 degrees in this embodiment), and both end openings thereof are formed on the coated polyethylene pipe 100. It becomes the receiving port 16 which receives a pipe end. Each of the receiving ports 16 is formed as an electrofusion joint 58. A heating wire 18 is embedded in the inner surface of each receiving port 16. In addition, two terminal portions 22 connected to the heating wire 18 and one indicator 24 are formed on the outer surface of each receiving port 18 so as to protrude.

  The surface of the joint body 12 is covered with the heat shrinkable tube 14. The body 26 of the heat shrinkable tube 14 has insertion holes 28 and 30 at positions corresponding to the terminal portions 22 and the indicators 24 of the receiving ports 16. Is formed. Further, both end portions of the main body 26 protrude outward in the axial direction from the open ends of the receiving ports 16, and annular collar portions 32 are formed there. As shown in FIG. 14, the flange portion 32 is formed between the opening end of the receiving port 16 and the outer layer 104 of the coated polyethylene tube 100 when the receiving port 16 of the joint body 12 receives the tube end of the coated polyethylene tube 100. Cover the gap that can be made from above.

  In the case where a coating layer is formed on the surface of the joint body 12, the joint body 12 is accommodated in the heat-shrinkable tube 14 before shrinkage, although illustration is omitted. Then, the ring body 34 and the shrinkage prevention core 40 are attached to each receiving port 16 of the joint body 12.

  Subsequently, they are put in a heating furnace such as a gear oven and heated at a predetermined temperature for a predetermined time, whereby the heat shrinkable tube 14 is reduced in diameter and brought into close contact with the surface of the joint body 12. When the heat treatment is completed, the heat shrinkable tube 14 is appropriately cooled and solidified by passing through a cooling water tank or the like.

  Then, the flange portion 32 of the heat-shrinkable tube 14 is cut along the axial end surface of the ring body 34, and then the shrinkage prevention core 40 is removed, and the ring body 34 disposed in the flange portion 32 is further removed, Exit.

  Also in this embodiment, as in the embodiment of FIG. 1, weather resistance can be imparted to the entire pipe line with a simple operation, and therefore, workability is excellent. Moreover, since the coating layer which coat | covers the outer surface of the joint main body 12 is strong with respect to the impact from the outside, and a fall of a coating layer etc. does not arise easily, possibility of the deterioration of a weather resistance resulting from it can be suppressed.

  In this embodiment, the joint body 12 includes the bent pipe portion 56 having a bending angle of 11.25 degrees. However, the present invention is not limited to this, and the bending angles are 90 degrees, 45 degrees, and 22.5 degrees. The same applies to the joint main body 12 including a curved pipe portion of the same degree.

  Furthermore, in the above-described embodiment, when the ring body 34 and the shrinkage prevention core 40 are attached to the receiving port 16 of the joint body 12, the ring body 34 is inserted into the flange portion 32 of the heat shrinkable tube 14, and Although the axial end surface is arranged along the opening end of the receiving port 16 so that the tip end surface of the convex portion 38 is flush with the inner surface of the receiving port 16, it is not necessary to be limited to this.

  For example, during heating in the heating furnace, the flange 32 that is thermally contracted is pressed from the inner surface side, whereby the flange 32 can be held in a shape in which the inner diameter is larger than the outer diameter of the coated polyethylene pipe 100. If it is, the shape of the ring body 34 will not be ask | required in particular.

  Further, the shrinkage preventing core 40 is inserted into the ring body 34 and the receiving port 16 of the joint body 12 until the stepped portion 44 is locked to the convex portion 38 of the ring body 34. However, the present invention is not limited to this. Nor.

  For example, the shape and dimensions of the receiving port 16 of the joint body 12 can be maintained by pressing the receiving port 16 of the joint body 12 to be thermally contracted from the inner surface side during heating in the heating furnace. If there is, the shape of the shrinkage-preventing core 40 is not particularly limited.

  As an example, an indication of positioning when inserting the anti-shrinkage core 40 is displayed by pasting an object described in paint or paper on the outer peripheral surface of the main body 42 of the anti-shrinkage core 40. By doing so, there is no need to lock the stepped portion 44 of the shrinkage-preventing core 40 to the convex portion 38 of the ring body 34. That is, it is not necessary to form the stepped portion 44 in the shrinkage preventing core 40, and it is not necessary to form the convex portion 38 on the inner peripheral surface of the ring body 34.

  Further, if the shrinkage prevention core 40 can be removed from the receiving port 16 of the joint body 12 after the heat treatment in the heating furnace, the gripping portion 46 is not necessarily provided at the other end of the body 42 of the shrinkage prevention core 40. There is no need to form.

  Furthermore, the ring body 34 may be formed integrally with the shrinkage prevention core 40. For example, in the above-described embodiment, when the anti-shrink core 40 is removed from the receiving port 16 of the joint body 12, the grip portion 46 of the anti-shrink core 40 is pulled with an air cylinder or the like while the ring body 34 is fixedly held. However, when the ring body 34 is formed integrally with the shrinkage prevention core 40, the joint body 12 is removed with a vise (vise) or the like when the shrinkage prevention core 40 is removed from the receiving port 16 of the joint body 12. In a fixed state, it is preferable to pull the grip 46 of the shrinkage prevention core 40 with an air cylinder or the like.

  It should be noted that the specific numerical values such as the diameter and height described above are merely examples, and can be appropriately changed as necessary.

DESCRIPTION OF SYMBOLS 10 ... Electrofused joint 12 ... Joint main body 14 ... Heat-shrinkable tube 16 ... Receptacle 18 ... Heating wire 22 ... Terminal part 24 ... Indicator 28, 30 ... Insertion hole 32 ... Girder part 34 ... Ring body 40 ... Shrink prevention core 100 ... Coated polyethylene pipe 102 ... Inner pipe 104 ... Outer layer 200 ... Coated polyethylene pipe

Claims (5)

An electric fusion joint for coated polyethylene pipes used to connect the coated polyethylene pipes,
A joint body made of polyethylene and having a receiving port for receiving the pipe end of the coated polyethylene pipe, and is covered with the surface of the fitting main body and protrudes axially from the opening end of the receiving port, and has an inner diameter that is the coated polyethylene pipe An electrofusion joint for a coated polyethylene pipe, comprising a heat-shrinkable tube having a flange portion that is larger than the outer diameter. The joint body is provided with a heating wire embedded in an inner surface of the receiving port, a terminal portion provided to project from the outer surface of the receiving port and energizing the heating wire, and a projecting surface from the outer surface of the receiving port. And an indicator for indicating that the inner surface of the receiving port and the pipe end of the coated polyethylene pipe are fused,
The electrofusion joint for coated polyethylene pipes according to claim 1, wherein an insertion hole for inserting the terminal portion and the indicator is formed in the heat shrinkable tube.   The joint body was accommodated in the heat-shrinkable tube before shrinkage, and heated with the shrinkage-preventing core inserted into the receiving port, thereby shrinking the heat-shrinkable tube and covering the surface of the joint body. The electrofusion joint for coated polyethylene pipes according to claim 1 or 2.   The electrofusion joint for coated polyethylene pipes according to claim 3, wherein an inner diameter of the flange portion is set by a ring body integrated with or attached to the shrinkage prevention core. 5. A coated polyethylene pipe in which coated polyethylene pipes, in which the outer peripheral surface of an inner pipe formed of polyethylene is coated with an outer layer, are joined using the electric fusion joint for coated polyethylene pipes according to any one of claims 1 to 4. ,
The length of the outer layer to be removed from the portion to be joined to the coated polyethylene pipe is set to a length that allows the joint body to receive the pipe end portion of the coated polyethylene pipe by the flange of the heat-shrinkable tube. Set the range to the remaining outer layer of the tube to a predetermined length that can be covered,
Furthermore, after the fusion-bonded polyethylene pipe and the electro-welded joint for the coated polyethylene pipe are fusion-bonded, the terminal portion of the joint body is removed to seal the insertion hole of the heat-shrinkable tube. Pipeline.

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