JP2007205507A - Multilayer pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer pipe easy to bend and superior in strength at welded portions of a metal intermediate layer. <P>SOLUTION: The multilayer pipe comprises a plurality of layers including the metal intermediate layer, the metal intermediate layer using band metal plates cylindrically formed with their both-side edges joined to each other and their joint portions welded to each other. The joint portions each have both-side edges shaped corresponding to each other so that the thickness of the joint portion is the same as the plate thickness of the meal intermediate layer and the joint area is larger than the face formed along the direction corresponding to the plate thickness and the longitudinal direction of the metal plate. They are formed by joining both-side edges to each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multilayer pipe composed of a plurality of layers including a metal intermediate layer among pipes used for transferring fluid such as water supply, hot water supply, cooling / heating, drainage, and air conditioning refrigerant.

  In a pipe used for transferring a fluid, various performances are required depending on the transfer conditions of the fluid. For example, pipes for hot water supply and cold / hot water are required to have long-term safety in a high temperature region, safety against electrochemical corrosion and water quality change, easy workability due to flexibility and lightness, and the like. Sprinkler piping is required to have a performance capable of withstanding severe conditions such as pressure resistance, vibration resistance, earthquake resistance, and durability.

  It is not easy to satisfy these various performances with a tube made of a single material. Therefore, the outer and inner surfaces of a metal tube (layer) with excellent mechanical strength can have heat resistance and corrosion resistance. Conventionally, three-layer pipes (multi-layer pipes) each provided (coated) with an excellent thermoplastic resin layer have been provided.

Such a three-layered tube is first formed into a cylindrical shape by joining both side edges of a strip-shaped metal plate having both side edges formed in a straight line so as to overlap or abut each other. After forming a metal tube (metal intermediate layer) by welding, a thermoplastic resin is coated (arranged) on the inner and outer peripheral surfaces of the metal tube and cut into a predetermined length. (See Patent Documents 1 and 2).
JP-T-2002-516773 Japanese Patent Laid-Open No. 7-156241

  By the way, among the three-layered tubes formed as described above, those having a metal intermediate layer in which both side edges of the band-shaped metal are overlapped and welded to each other are arranged in the circumferential direction in the axial length direction of the metal intermediate layer. Since the portion is welded with the side edges overlapped, the thickness of the metal intermediate layer is doubled only in this portion. For this reason, there has been a problem in that it is difficult to bend the tube when bending the tube as compared with the three-layer simpler having a metal intermediate layer having a constant thickness in the circumferential direction.

  On the other hand, those having a metal intermediate layer welded with both sides of the strip metal butted against each other have a smaller welded area than the metal intermediate layer welded with the side edges overlapped, and therefore the strength of the welded portion. There has been a problem that (weld strength) becomes small.

  In view of the above problems, an object of the present invention is to provide a multilayer pipe that is easy to bend and that has a high weld strength of a metal intermediate layer.

  Therefore, in order to solve the above-mentioned problems, the multilayer tube according to the present invention is formed by forming a strip-shaped metal plate into a cylindrical shape by joining both side edges thereof and welding the joint. In a multilayer tube composed of a metal tube as a metal intermediate layer and composed of a plurality of layers including the metal intermediate layer, the thickness of the bonded portion is the same as the thickness of the metal intermediate layer. The side edges are formed in corresponding shapes so that the joining area is larger than the surface along the direction corresponding to the plate thickness and the longitudinal direction of the metal plate. It is formed by joining together.

  By adopting the above-described configuration, the corresponding side edge portions are joined to each other and welded to form a metal middle so that the metal in the circumferential direction has a constant thickness (plate thickness) and a large welding area. A multilayer tube with an intermediate layer can be obtained.

  Moreover, the said junction part is good also as a structure formed by superimposing the said both-sides edge part which each has a thickness change corresponding to each other so that thickness may become fixed when superimposing.

  By adopting the above-described configuration, the joining area becomes larger than joining the side surfaces (side edge portion end faces) of the belt-like metal plate along the plate thickness direction and the longitudinal direction, and when overlapping, this overlapping portion Can be joined to have the same thickness as other portions (plate thickness) of the metal intermediate layer. Accordingly, it is possible to form a metal intermediate layer having a constant thickness (plate thickness) in the circumferential direction (uniform thickness). As a result, it is possible to form a multilayer pipe that is easily bent in an arbitrary direction and has a high weld strength of the metal intermediate layer.

  Further, the thickness change is such that one side edge portion gradually decreases toward the end portion and along one surface, and the other side edge portion extends toward the end portion and along the other surface. It is good also as a structure formed by thickness decreasing gradually.

  By adopting the above-described configuration, the joint surface has less complex irregularities, so that it becomes easier to process both side edges of the strip metal. Moreover, it becomes easy to perform welding work.

  Moreover, the said junction part is good also as a structure formed by abutting the said both-sides edge part each formed in the non-linear shape corresponding to each other.

  By adopting the above configuration, the length of the side edge portion is longer than that of the non-linear side edge portion than the straight side edge portion along the longitudinal direction. The joining area increases and the welding area also increases. As a result, a metal intermediate layer having a constant thickness in the circumferential direction and high welding strength can be obtained.

  Moreover, the said non-linear shape is good also as a structure formed so that the trough part and peak part which change in the direction orthogonal to the longitudinal direction of the said metal plate may be arrange | positioned alternately.

  Even in the above-described configuration, the length of the side edge portion is increased as described above, and thus the bonding area is increased. As a result, a metal intermediate layer having a constant thickness in the circumferential direction and a high welding strength can be obtained, and a multilayer pipe that is easy to bend in any direction and has a high weld strength of the metal intermediate layer is formed. Will be able to.

  In addition, the joint portions have thickness changes corresponding to each other so that the thickness is constant when they are overlapped, and the both side edges formed in non-linear shapes corresponding to each other are joined. It is good also as a structure formed by this.

  By setting it as the said structure, the joining area of the said junction part becomes large like the above. Therefore, it becomes possible to obtain a metal intermediate layer having a constant thickness in the circumferential direction and high welding strength, and forming a multilayer tube that is easily bent in any direction and has a high weld strength of the metal intermediate layer. Will be able to.

  The metal intermediate layer may be made of aluminum.

  By setting it as the said structure, it becomes difficult to permeate | transmit oxygen in air | atmosphere in the said multilayer tube. That is, it is possible to prevent oxygen in the atmosphere from passing through the inside (inside the pipe) through the wall of the multilayer pipe and dissolving in the fluid.

  As a result, for example, when the multilayer pipe is used as a pipe when circulating hot water for cooling and heating, etc., oxygen in the atmosphere permeates through the pipe wall of the hot water pipe and dissolves in the fluid (hot water). If the product is used for a long time in this state, oxygen dissolved in the hot water inside may oxidize and corrode metal parts such as a heat source machine, but the oxygen does not permeate the tube wall. Oxygen dissolved therein can be eliminated, and the oxidative corrosion can be prevented.

  Furthermore, since the specific gravity of aluminum is smaller than that of other metals, the weight of the multilayer pipe can be reduced, so that piping work can be easily performed, and workability is improved.

  The metal intermediate layer may be formed of copper or SUS.

  By setting it as the said structure, it can make it difficult to permeate | transmit oxygen into a pipe | tube like the above. Further, since copper or SUS has excellent corrosion resistance against water, there is no problem even if it comes into contact with water. Therefore, when the multilayer pipe is used for hot water supply or water supply, that is, the fluid flowing in the pipe is water. In this case, it is possible to directly branch out water (or hot water) flowing through the pipe by making a hole in the pipe wall where the metal intermediate layer is disposed without using a pipe joint for branching. Become.

  Moreover, it is good also as a structure which further arrange | positions a metal intermediate | middle layer so that the said metal intermediate | middle layer may be opposed.

  By setting it as the said structure, since the number of metal intermediate | middle layers increases, the intensity | strength of the said multilayer tube becomes large.

  Moreover, it is good also as a structure which further arrange | positions the heat insulating material of thickness 3mm or less on the outer peripheral surface of outermost layer.

  By setting it as the said structure, a multilayer pipe | tube (multilayer pipe | tube with a heat insulating material) provided with sufficient heat retention function can be obtained, without enlarging an outer diameter too much here now. Accordingly, handling at the construction site is facilitated, and workability is improved. Furthermore, since the heat insulating material is as thin as 3 mm or less, the outer diameter of the entire multilayer tube including the heat insulating layer (heat insulating material) is not so large and bending is easy to perform.

  As described above, according to the present invention, it is possible to provide a multilayer pipe that is easy to bend and has a high weld strength of the metal intermediate layer.

  Hereinafter, a multilayer tube according to a first embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the multilayer tube 1 according to the present embodiment is formed as a cylindrical body having the same diameter in the axial direction, and the tube wall includes a plurality of layers along the circumferential direction. That is, it is configured by arranging a plurality of tubular (tubular) layers having the same central axis so as to be laminated. In the case of this embodiment, an inner layer (innermost layer) 2 formed of a thermoplastic resin from the inside of the multilayer tube 1 toward the outside (radially outward from the central axis), a metal intermediate layer 3 formed of metal, It is comprised by laminating | stacking three layers with the outer layer (outermost layer) 4 formed with a thermoplastic resin in order.

  More specifically, for example, the multilayer pipe 1 is formed as a cylindrical body having an outer diameter of 16 mm, an inner diameter of 12 mm, and a wall thickness (the thickness of the pipe wall) of about 2 mm. It is used as piping for use. The thickness of each layer is 0.90 mm for the inner layer 2, 0.20 mm for the metal intermediate layer 3, and 0.90 mm for the outer layer. Each layer is bonded via an adhesive layer (adhesive) 5. The adhesive layer 5 is made of deformed polyethylene and has a thickness of approximately 0.05 mm. In the three layers constituting the multilayer tube 1, the inner layer 2 and the outer layer 4 are made of high heat-resistant polyethylene, and the metal intermediate layer 3 is made of reinforced aluminum.

  The respective layers need not be limited to the above materials. That is, the inner layer 2 only needs to be flexible and have corrosion resistance to the fluid flowing in the multilayer tube 1, so that vinyl chloride, polyethylene, crosslinked polyethylene, polypropylene, acrylic resin, fluorine resin, amide resin Further, it may be a thermoplastic resin such as silicone resin, polyethylene terephthalate, or polybuden.

  Further, the outer layer 4 may be the same thermoplastic resin as the inner layer 2, and further protects the metal intermediate layer 3 and improves the heat retaining property, such as soft vinyl chloride resin, natural rubber, synthetic rubber, etc. It may be a plastic resin.

  Further, the metal intermediate layer 3 need not be limited to reinforced aluminum as long as it has a low oxygen permeability and can be easily bent and fixed when placed on the pipe. Therefore, metals such as aluminum, aluminum alloy, iron, copper, and SUS may be used. Further, the adhesive layer 5 need not be limited to deformed polyethylene.

  As shown in FIG. 2, the metal intermediate layer 3 is formed into a cylindrical shape by joining the side edges 31 and 32 of a single band-shaped reinforced aluminum plate to each other and welding the joint 33 as described later. It is a thing. The side edge portion 31 on one side of the reinforced aluminum plate is formed in a shape in which the outer peripheral surface (surface) is cut out from the end portion 34 by a certain width and a certain thickness in the axial length direction. The side edge portion 32 on the other side has an inner circumferential surface (width and thickness corresponding to the cutout of the side edge portion 31 on the one side) from the end portion 35 in the axial length direction by a certain width and a certain thickness. The back surface is formed in a cut-out shape. That is, when the cut-out surfaces 36 and 37 are overlapped so that the cut-out surfaces 36 and 37 are in contact (opposed), the entire surfaces of the cut-out surfaces 36 and 37 are in contact with each other, and the thickness of the overlap portion is the plate thickness of the metal intermediate layer 3. It is a notch shape which becomes the same. In the case of this embodiment, it is notched so as to have a width of 1.0 to 10.0 mm and a thickness of 0.1 mm.

  The joining portion 33 is configured by joining the notched side edges 31 and the notched surfaces 36 and 37 of the other side edge 32 so as to contact each other. By welding these portions as described later, a band-shaped reinforced aluminum plate is formed in a cylindrical shape, and a metal tube (metal intermediate layer) 3 is formed. At this time, when the metal intermediate layer 3 is viewed in plan, the joint portion 33 of the side edge portions 31 and 32 appears linearly along the central axis (the central axis of the multilayer tube 1).

  Next, the manufacturing method of the multilayer tube according to the present embodiment will be described with reference to FIG. 3. First, the manufacturing apparatus 40 will be described.

  In FIG. 3, reference numeral 41 denotes a supply bobbin of a band-shaped reinforced aluminum material. Reference numeral 42 denotes a pretreatment tank, which can perform, for example, a degreasing treatment, a rust removal treatment, and a rust prevention treatment. 43 is a U-shaped shaping apparatus. Reference numeral 44 denotes a circular tube shaping device, in which a U-shaped band-shaped reinforced aluminum material 110 is shaped (formed) in a tubular shape. 45 is a welding machine, and is used for joining joints at both side edges of the strip-shaped reinforced aluminum material 110 shaped in a tubular shape. Reference numeral 46 denotes a thermoplastic resin extrusion die, which includes a horizontal cylindrical passage portion 461, a vertical passage portion 462, and a box portion 463 each having a discharge port for discharging an adhesive along the outer periphery of the tip portion and discharging high heat-resistant polyethylene. The vertical passage portion 462 is inserted into the opening of the semi-tubular reinforced aluminum material 110 conveyed between the U-shaped shaping device 43 and the tubular shaping device 44, and the horizontal cylindrical passage portion 461 is strengthened in the tubular shaping. It is inserted into the aluminum material, and the discharge part 464 is positioned downstream of the welding machine 45. 47 is an extrusion device for coating the outer layer of the thermoplastic resin, 48 is a cooling tank, and 49 is a cutting device.

  In order to manufacture the multilayer tube 1 using the manufacturing apparatus 40, first, the coil of the band-shaped reinforced aluminum material 110 is supplied to the supply bobbin 41.

  The coil of the reinforced aluminum material 110 is obtained by winding a strip-shaped reinforced aluminum plate having a constant width. This band-shaped reinforced aluminum plate has a side edge (longitudinal edge) surface on one side, a constant width from the end to the inside, and half of the thickness of the reinforced aluminum plate is cut out, and the other side The side edge portion back surface is formed in a shape corresponding to the cutout on the one side and half of the thickness of the reinforced aluminum plate cut out from the end portion to the inside.

  Next, after performing a predetermined pretreatment in the pretreatment tank 42, the band-shaped reinforced aluminum material 110 is passed through the U-shaped shaping device 43, and the band-shaped reinforced aluminum material 110 is shaped (formed) into a U-shape. Go. Further, the U-shaped aluminum material 110 is formed into a tubular shape by overlapping (joining) the notches formed on both side edges of the band-shaped reinforced aluminum material 110 with the tubular shaping device 44, and then combined. The eyes (joining part) are welded by a welding machine 45. The adhesive (modified polyethylene) is discharged from the outer periphery of the distal end of the horizontal cylindrical passage portion 461 of the thermoplastic resin extrusion mold 46 to the inner surface of the welded metal tube, and the thermoplastic resin (high heat resistant polyethylene) is discharged. Cover the inner peripheral surface of the metal tube.

  In this manner, after the thermoplastic resin layer (inner layer of the multilayer tube 1) is extrusion coated, the outer peripheral surface of the metal tube is coated with the thermoplastic resin layer (outer layer of the multilayer tube 1) by the extrusion device 47. The metal tube coated with the inner layer and the outer layer is cooled by passing through the cooling bath 48 and is cut into a predetermined length by the cutting device 49 to obtain the multilayer tube 1.

  As shown in FIGS. 1 and 2, the multilayer tube 1 manufactured as described above has a uniform thickness in the circumferential direction of the metal intermediate layer 3, and therefore, along the place where the multilayer tube 1 is disposed. It becomes easier to bend when bent into a different shape.

  That is, by providing notches corresponding to each other at both side edges of the belt-like reinforced aluminum plate for forming the metal intermediate layer 3, the contact (joining) area when the both side edges are overlapped to form a cylinder. And the metal intermediate layer 3 having a uniform thickness in the circumferential direction and a large joint area can be formed. become. Therefore, the multilayer tube 1 including the metal intermediate layer 3 is easier to bend than a conventional multilayer tube in which the thickness of the joint portion (overlapping portion) of the metal intermediate layer is larger than the plate thickness.

  In addition, the present embodiment is applied to the metal intermediate layer of the conventional multilayer tube in which both side edges of the straight strip-shaped aluminum plate whose both side edges are along the longitudinal direction are joined to each other and welded. The metal intermediate layer 3 of the multilayer tube 1 is joined by overlapping the both side edges of the band-shaped reinforced aluminum plate with both side edges notched so that the notched surfaces 36 and 37 are in contact (opposing), In order to weld such a joint, the weld area is increased, and the weld strength of the weld is improved. Therefore, by providing such a metal intermediate layer 3, it is possible to obtain a multilayer tube that is easy to bend and has a high weld strength of the metal intermediate layer.

  Next, a multilayer tube according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. Since the multilayer tube according to this embodiment has substantially the same configuration as the multilayer tube according to the first embodiment except for the metal intermediate layer, only the metal intermediate layer 6 will be described in the following description. About the corresponding structure, the same name and the same code | symbol as 1st embodiment are attached | subjected, and description is omitted.

  Similarly to the first embodiment, the metal intermediate layer 6 is formed in a cylindrical shape by joining the side edges 61 and 62 of a single reinforced aluminum plate to each other and welding the joint 63. The side edge portion 61 on one side of the reinforced aluminum plate is formed in a shape in which concave portions and convex portions in the direction orthogonal to the longitudinal direction are alternately arranged. More specifically, a shape having an inclined side of 45 ° with respect to the longitudinal direction of the reinforced aluminum plate, and a valley portion and a mountain portion that are bent at right angles are continuously arranged (a so-called zigzag shape). Is formed. The side edge 62 on the other side has alternating protrusions (peaks) and recesses (valleys) in the direction perpendicular to the longitudinal direction so that the end corresponds to the side edge on the one side. It is formed in the shape arrange | positioned. That is, when the side edge portions 61 and 62 are brought into contact with each other, the peak portion on one side and the valley portion on the other side are in contact with each other without any gap, and the valley portion on one side and the peak portion on the other side are without gaps. It is a side edge shape that makes contact. In the case of the present embodiment, the zigzag shape is such that the length of the hypotenuse is 1.0 to 10.0 mm and the angle of the bent portion is 90 °.

  The metal intermediate layer 6 is formed by joining the side edge portion 61 on one side and the side edge portion 62 on the other side of the zigzag so as to abut each other and welding the portion. At this time, when the metal intermediate layer 6 is viewed in plan, the joint 63 between the side edges 61 and 62 appears as a zigzag shape along the central axis.

  The metal intermediate layer 6 according to the present embodiment need not be limited to reinforced aluminum, and may be formed of various metals as in the first embodiment.

  As described above, the multilayer tube according to this embodiment is formed with a uniform (constant) thickness in the circumferential direction of the metal intermediate layer 3 as in the first embodiment. It becomes easy to bend when it bends in the shape along.

  That is, since both side edge portions of the belt-like reinforced aluminum plate are brought into contact with each other and joined, the thickness of the joined portion is the same as the thickness (plate thickness) of other portions. Therefore, as in the first embodiment, the thickness in the circumferential direction of the metal intermediate layer 6 formed from the band-shaped reinforced aluminum plate is uniform (constant), and the multilayer tube 1 including the metal intermediate layer 6 has a desired thickness. It becomes easy to bend the shape.

  In addition, the side edges 61 and 62 that are joined to each other when they are formed into a cylindrical shape have a shape in which peaks and valleys are alternately arranged in a direction orthogonal to the central axis direction (longitudinal direction). Since it is formed, the contact area becomes larger when joining than the linear side edges along the longitudinal direction. Accordingly, the welding area is increased and the welding strength is improved. Therefore, as in the first embodiment, by providing the metal intermediate layer 6, it is possible to obtain a multilayer tube that is easy to bend and has a high weld strength of the metal intermediate layer.

  The multilayer pipe of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention.

  For example, as shown in FIG. 2, in the first embodiment, the joint surface (joint portion) 33 is formed so as to appear stepwise in the axial length direction, but it is not necessary to be limited to this. As shown in FIG. 6 (a), in the axial length direction, the joining surface 70 is at a constant angle with respect to the outer peripheral surface 71 and the inner peripheral surface 72. As shown in FIG. 6 (b), the joining surface 80 advances in the circumferential direction in the axial length direction, while the thickness direction extends from the outer circumferential surface 81 to the inner circumference as shown in FIG. After going back to the surface 82 and returning from the inner peripheral surface 82, which is the opposite direction, to the outer peripheral surface 81, it again appears in the shape from the outer peripheral surface 81 toward the inner peripheral surface 82, that is, substantially S-shaped. May be formed. Even with such a joint surface, the joint area increases, so the weld area also increases and the weld strength increases. In addition, since the thickness of the junction can be kept the same as the plate thickness, the thickness of the junction (overlapping portion) of the metal intermediate layer is larger than that of the conventional multilayer tube, which is thicker than the plate thickness. easy.

  In the second embodiment, the joining surface 63 is formed on the outer peripheral surface of the metal intermediate layer 6 so as to appear in a zigzag shape along the central axis. However, the present invention is not limited to this, and the joining surface 63 is not limited thereto. As shown in FIGS. 6C and 6D, 'may appear in an arc shape or may appear in a meandering shape. That is, if it is a joining surface that appears as a shape other than a linear shape along the central axis on the outer peripheral surface, the joining area increases and the welding strength increases.

  In addition, even on the outer peripheral surface as shown in FIG. 7, even a joint surface 63 ′ that appears in a zigzag shape along the central axis and has a certain angle with the circumferential direction in the axial length direction is joined. The area can be increased.

  Further, in the present embodiment, the metal intermediate layer 3 is configured as a three-layer tube in which the inner layer 2 and the outer layer 3 are disposed one by one on the inner peripheral surface and the outer peripheral surface, but it is necessary to be limited to this. Alternatively, a multilayer pipe in which a plurality of thermoplastic resin layers are disposed on the inner and outer peripheral sides of the metal intermediate layer 3 may be used.

  In addition to the metal intermediate layer 3, an intermediate layer made of metal may be further provided. In that case, the metal layers may be adjacent to each other (may be stacked so as to face each other), or may be disposed so as to sandwich another layer between the metal layers. In that case, each metal layer does not need to be the same material, and may be formed with a different material. Similarly, in the thermoplastic resin layer, the inner layer 2 and the outer layer 4 are formed of the same thermoplastic resin, but they need not be formed of the same material, and may be formed of different materials.

  Moreover, when comprised from a some thermoplastic resin layer, each layer may be formed with the same raw material, and may be formed with a different raw material.

  Moreover, it is good also as a multilayer tube with a heat insulating material by arrange | positioning 3 mm or less heat insulating material (heat insulating material) in the outer peripheral surface of the multilayer tube 1 which concerns on this embodiment. In this case, since the inner layer 2 and the outer layer 4 formed of thermoplastic resin are respectively disposed on the inner side and the outer side of the metal intermediate layer 3, even if the thickness of the heat insulating material is reduced, the fluid flowing inside is sufficiently kept warm. can do. In addition, by reducing the thickness of the heat insulating material, the outer diameter of the multilayer tube with the heat insulating material does not become too large, so that it is easy to bend and handle at the construction site.

  In this case, examples of the heat insulating material include foamed thermoplastic resins such as foamed crosslinked polyethylene, foamed polypropylene, foamed acrylic resin, and foamed urethane resin, and glass wool.

1 is a partially cutaway perspective view of a multilayer tube according to a first embodiment. (A) of the multilayer tube which concerns on the embodiment shows a front view, (b) shows a plan view. The schematic block diagram of the manufacturing apparatus of the multilayer tube concerning the embodiment is shown. The partial notch cross-sectional perspective view of the multilayer tube which concerns on 2nd embodiment is shown. (A) of the multilayer tube which concerns on the embodiment shows a front view, (b) shows a plan view. (A) and (B) are front views of modified examples of the joint portion of the multilayer tube according to the first embodiment, and (C) and (D) are joint portions of the multilayer tube according to the second embodiment. The top view about these modifications is shown. (A) shows the front view about the modification of the junction part of the multilayered tube which concerns on 1st and 2nd embodiment, (b) shows the same top view.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multilayer pipe, 2 ... Inner layer, 3 ... Metal intermediate | middle layer (metal pipe), 4 ... Outer layer, 5 ... Adhesive layer, 6 ... Metal intermediate | middle layer, 33 ... Joining part (joint surface), 40 ... Manufacturing apparatus, 41 ... Supply bobbin, 42 ... pretreatment tank, 43 ... U-shaped shaping device, 44 ... tubular shaping device, 45 ... welding machine, 46 ... thermoplastic resin extrusion mold, 461 ... horizontal cylindrical passage, 462 ... vertical passage 463 ... Box part, 464 ... Discharge part, 47 ... Extrusion device, 48 ... Cooling tank, 49 ... Cutting device, 63, 63 '... Joining part (joining surface)

Claims (10)

  A strip-shaped metal plate is formed into a cylindrical shape by joining both side edges thereof, and a metal tube formed by welding the joint is used as a metal intermediate layer, and a plurality of layers including the metal intermediate layer In the multi-layer tube constituted by the metal pipe, the joining portion has a thickness that is the same as the thickness of the metal intermediate layer, and the joining area has a direction corresponding to the plate thickness and the metal. A multilayer pipe characterized in that the side edges are formed in corresponding shapes so as to be larger than the plane along the longitudinal direction of the plate, and the side edges are joined to each other.   The multilayer pipe according to claim 1, wherein the joining portion is formed by superposing the both side edge portions having thickness changes corresponding to each other so that the thickness becomes constant when they are superposed. .   The thickness change is such that one side edge gradually decreases in thickness toward one end and along one surface, and the other side edge increases in thickness toward the end and along the other surface. The multilayer pipe according to claim 2, wherein the multilayer pipe is formed by gradually decreasing.   The multilayer pipe according to claim 1, wherein the joint portion is formed by abutting the side edge portions formed in non-linear shapes corresponding to each other.   5. The multilayer according to claim 4, wherein the non-linear shape is formed so that valleys and peaks changing in a direction orthogonal to a longitudinal direction of the metal plate are alternately arranged. tube.   The joint portions have thickness changes corresponding to each other so that the thickness is constant when they are overlapped, and by joining the both side edges respectively formed in non-linear shapes corresponding to each other. The multilayer pipe according to claim 1, wherein the multilayer pipe is formed.   The multilayer pipe according to any one of claims 1 to 6, wherein the metal intermediate layer is formed of aluminum.   The multilayer pipe according to any one of claims 1 to 6, wherein the metal intermediate layer is formed of copper or SUS.   The multilayer tube according to claim 1, further comprising a metal intermediate layer disposed so as to face the metal intermediate layer.   The multilayer tube according to any one of claims 1 to 9, wherein a heat insulating material having a thickness of 3 mm or less is further disposed on the outer peripheral surface of the outermost layer.

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