Piping structure and prefabricated pipe

Abstract

To provide a piping structure and a prefabricated pipe that are capable of stably securing sealing performance without excessive enlargement.SOLUTION: A sealing member 30 is accommodated in a closed annular groove portion 101 formed in the circumferential direction of an opening portion 11a of a first engaging portion 13, with its inner peripheral side exposed to a flow path FP inside a first piping member 10 and a second piping member 20. A first bulging portion 12 has a first tapered surface 12b on a side opposite to a first abutting surface 12a, and a second bulging portion 22 has a second tapered surface 22b on a side opposite to a second abutting surface 22a. A joining member 90 includes a plurality of divided members 91 and 92 each having a first contact tapered surface 911a, 921a that comes into contact with the first tapered surface 12b and a second contact tapered surface 911b, 921b that comes into contact with the second tapered surface 22b, the plurality of divided members 91 and 92 being connected by a fastener extending in a direction perpendicular to the pipe axis direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a piping structure and a prefabricated piping. [Background technology]

[0002] Conventionally, resin piping members have been used as piping through which fluid flows. As a structure for connecting such piping members, a piping structure is known in which flanges provided at the ends of the piping members are opposed to each other and the flanges are engaged with each other with a packing (sealing member) sandwiched between the flanges (see, for example, Patent Document 1). Known uses of the piping structure include piping for water supply, hot water supply, drainage, air conditioning, gas, and fuel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-250407 Summary of the Invention [Problem to be solved by the invention]

[0004] In the piping structure described in Patent Document 1, when an external force (e.g., bending stress) is applied to the connected piping, stress tends to concentrate near the flanges, which are the joints between the piping components. Furthermore, compared to metal piping components, resin piping components are more susceptible to thermal expansion and contraction due to temperature changes, making them more susceptible to stress at the joints. When stress is applied to the joints in this way, the flanges may separate, resulting in water leakage.

[0005] Therefore, in the above-mentioned piping structure, a sealing member that is relatively larger than the sealing member used in metal piping is used to suppress water leakage.

[0006] However, when using a larger seal member to improve sealing performance, it is necessary to enlarge the flange of the piping member to match the size of the seal member, which results in a problem that the outermost dimensions of the piping member become larger and makes installation more difficult.

[0007] Furthermore, when a large seal member is used, the tightening torque required to compress the seal member and achieve sealing performance also becomes relatively large, which may reduce work efficiency when assembling the piping structure.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a piping structure that can stably ensure sealing performance without excessively increasing the size, and also to provide a prefabricated piping structure equipped with such a piping structure. [Means for solving the problem]

[0009] In order to solve the above problems, one aspect of the present invention includes the following aspects.

[0010] [1] A first piping member has a tubular first tubular portion that is open at both ends and a first bulging portion provided at one end of the first tubular portion, wherein the one end of the first tubular portion and the first bulging portion constitute a first engaging portion formed of a polyolefin-based resin; a second piping member has a tubular second tubular portion that is open at both ends and a second bulging portion provided at one end of the second tubular portion, wherein the one end of the second tubular portion and the second bulging portion constitute a second engaging portion formed of a polyolefin-based resin, and the second engaging portion is connected to the first engaging portion; a closed-ring seal member that is liquid-tightly sandwiched between the first engaging portion and the second engaging portion at a connecting portion between the first engaging portion and the second engaging portion; and a closed-ring joining member that surrounds and fixes the first bulging portion and the second bulging portion from an outer circumferential side at the connecting portion, wherein the first engaging portion has a first abutting surface that faces the second engaging portion and a second abutting surface that faces the second engaging portion. the second engaging portion has a second abutting surface that faces the first engaging portion and abuts against the first abutting surface; the sealing member is housed in the recessed rib portion and has an inner circumferential side exposed to flow paths within the first piping member and the second piping member; the first bulge portion has a first tapered surface opposite the first abutting surface, and the second bulge portion has a second tapered surface opposite the second abutting surface; the joining member is made of a plurality of divided members each having a first abutting tapered surface that abuts against the first tapered surface and a second abutting tapered surface that abuts against the second tapered surface, and the joining member is connected by fasteners that extend perpendicular to the pipe axis direction, thereby tightly adhering the first abutting surface and the second abutting surface and sandwiching the sealing member between the recessed rib portion and the second engaging portion.

[0011] [2] The second engaging portion is formed opposite the first engaging portion in the circumferential direction of the opening of the second tubular portion, and has a closed ring-shaped convex rib portion that fits into the concave rib portion, and the sealing member is sandwiched between the convex rib portion and the concave rib portion. [1] The piping structure described in [1].

[0012] [3] A piping structure according to [2], having a first metal plate that forms the first mating surface and the recessed streak portion of the first engagement portion, and a second metal plate that forms the second mating surface and the protruding streak portion of the second engagement portion.

[0013] [4] The piping structure described in [1], wherein the first engaging portion has a first recess formed circumferentially adjacent to the first bulge portion on the outer peripheral surface of the first tubular portion, and the second engaging portion has a second recess formed circumferentially adjacent to the second bulge portion on the outer peripheral surface of the second tubular portion, and the inner peripheral end of the joining member is inserted into the first recess and the second recess.

[0014] [5] A prefabricated pipe having the piping structure described in any one of [1] to [4], in which a fitting made of a resin material is connected to at least one of the other ends of the first tubular section and the second tubular section. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a piping structure that can stably ensure sealing performance without excessively increasing the size, and also to provide a prefabricated piping having such a piping structure. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic exploded perspective view showing a piping structure 100 according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is an enlarged end view of a connection point of the piping structure 100. FIG. [Figure 4] FIG. 4 is a partial end view illustrating the piping structure 100. As shown in FIG. [Figure 5] FIG. 5 is a partial end view illustrating the piping structure 100. As shown in FIG. [Figure 6] FIG. 6 is an end view showing the structure for preventing the packing from falling off. [Figure 7] FIG. 7 is an end view showing the structure for preventing the packing from falling off. [Figure 8] FIG. 8 is an end view showing the structure for preventing the packing from falling off. [Figure 9] FIG. 9 is an end view showing the structure for preventing the packing from falling off. [Figure 10] FIG. 10 is a cross-sectional view of a piping member 50 having a joint 40. As shown in FIG. [Figure 11] FIG. 11 is a cross-sectional view showing an example of a prefabricated piping 200 according to the first embodiment. [Figure 12] FIG. 12 is a partial end view of a piping structure 150 according to the second embodiment. [Figure 13] FIG. 13 is a cross-sectional view of a piping structure 250 according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] [First embodiment] A piping structure and prefabricated piping according to a first embodiment of the present invention will be described below with reference to Figures 1 to 11. In all of the following drawings, the dimensions and proportions of each component are appropriately changed to make the drawings easier to understand.

[0018] [Piping structure] Fig. 1 is a schematic exploded perspective view showing a piping structure 100. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1.

[0019] 1 and 2, the piping structure 100 includes a first piping member 10, a second piping member 20, and a packing (sealing member) 30. In the piping structure 100, the first piping member 10 and the second piping member 20 are connected. The packing 30 is sandwiched at the connection point between the first piping member 10 and the second piping member 20. The following explains each in order.

[0020] <First piping component> The first piping member 10 is a pipe having an internal space 10S and made of a resin material. A thermoplastic resin can be suitably used as the resin material constituting the first piping member 10. Any thermoplastic resin can be used, such as hard polyvinyl chloride resin, ABS, or AES, but from the viewpoint of earthquake resistance and durability, it is preferable to use a polyolefin resin, for example.

[0021] Piping components made from polyolefin resin (polyolefin resin pipes) have higher tensile breaking elongation measured according to JIS K 6815-1 and JIS K 6815-3 than piping components made from rigid polyvinyl chloride (rigid polyvinyl chloride resin pipes). While the tensile breaking elongation of rigid polyvinyl chloride pipes is 50-150%, the tensile breaking elongation of polyolefin resin pipes is 350% or more. In particular, when using PE100 high-density polyethylene pipes using the extrapolation method specified in ISO / TR9080, the tensile breaking elongation is 500% or more. This helps prevent damage caused by earthquakes.

[0022] The polyolefin resin is not particularly limited, but suitable examples include polypropylene, polybutene, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, and poly-α-olefin.

[0023] The melt mass flow rate (MFR) of the thermoplastic resin is, for example, preferably 0.1 to 25 g / 10 min, more preferably 0.1 to 10 g / 10 min, and even more preferably 0.29 to 0.45 g / 10 min. When the MFR is equal to or greater than the lower limit, molding becomes easy. When the MFR is equal to or less than the upper limit, thermal stability can be further improved. MFR can be measured in accordance with JIS K 7210:1999 at a test temperature of 220°C and a test load of 10 kg.

[0024] The specific gravity of the thermoplastic resin is, for example, 942 to 953 kg / m 3 is preferred. The specific heat of the thermoplastic resin is preferably, for example, 1.9 to 2.3 kJ / kg·K. The thermal conductivity of the thermoplastic resin is preferably, for example, 0.46 to 0.5 W / m·K.

[0025] The melting point of the thermoplastic resin (ie, the melting temperature of the first piping member 10) is preferably 150°C to 260°C, and more preferably 180°C to 240°C.

[0026] The resin material may contain, in addition to the thermoplastic resin, known additives such as pigments, ultraviolet absorbers, antioxidants, and lubricants, as well as fillers.

[0027] The first piping member 10 may be a single-layer pipe, or may have a multi-layer structure with a surface layer on at least one of the outer and inner surfaces. The surface layer may contain, for example, at least one of inorganic fibers and organic fibers. Examples of inorganic fibers include glass fibers, carbon fibers, silicon-titanium-carbon composite fibers, boron fibers, and metal fibers. Examples of organic fibers include aramid fibers, vinylon fibers, polyester fibers, and polyamide fibers. When the surface layer contains these fibers, the tensile strength of the first piping member 10 can be increased and thermal expansion can be further suppressed.

[0028] The surface layer may also contain a fluororesin, which can improve resistance to acids, alkalis, and the like (chemical resistance).

[0029] Furthermore, a layer similar to the surface layer may be provided inside the wall of the first piping member 10 .

[0030] The first piping member 10 may be a multi-layer pipe having three or more layers including a metal layer as an intermediate layer. Suitable metal materials for the metal layer include, for example, iron, brass, copper, stainless steel, aluminum, titanium, and silver alloy.

[0031] The first piping member 10 has a tubular first tubular portion 11 that is open at both ends, and a first bulging portion 12 that is provided at one end 11E of the first tubular portion 11. In the first piping member 10, the one end 11E of the first tubular portion 11 and the first bulging portion 12 that is provided at this one end 11E constitute a first engaging portion 13. Therefore, the first engaging portion 13 is also formed from a polyolefin resin such as a polyethylene resin.

[0032] (1st tubular part) The first tubular portion 11 has a tube main body 111 and a reduced tube portion 112 that is reduced inward in the radial direction of the tube main body 111 on one end side of the tube main body 111. That is, in the first tubular portion 11, it is preferable that the inner diameter W11 of the tube main body 111 is larger than the inner diameter W12 of the smallest diameter point of the reduced tube portion 112 (W11>W12), but they may be the same diameter.

[0033] A first recess 10C is formed on the outer peripheral surface of the first tubular portion 11 (the outer peripheral surface 10x of the first piping member 10) at a position overlapping with the tube contraction portion 112 and adjacent to the first bulge portion 12 in a field of view perpendicular to the tube axis Ax, which is the central axis of the piping structure 100. The first recess 10C is formed in the shape of an endless closed ring in the circumferential direction of the first tubular portion 11. The tube contraction portion 112 and the first recess 10C are provided in the first engagement portion 13. Hereinafter, the direction in which the tube axis Ax extends will be referred to as the tube axis direction.

[0034] The inner surface of the first tubular portion 11 (inner surface 10y of the first piping member 10) is composed of surface 10y1, which is the inner surface of the pipe main body 111 and is a surface along the pipe axis Ax, surface 10y2, which is the inner surface of the narrowed pipe portion 112 and is a surface along the pipe axis Ax, and inclined surface 10y3 connecting surface 10y1 and surface 10y2.

[0035] (1st bulge) The first bulging portion 12 has a structure that protrudes in an annular shape radially outward from the first piping member 10 at the reduced pipe portion 112. The first bulging portion 12 faces a second bulging portion 22 (described later) that the second piping member 20 has.

[0036] The first engagement portion 13 has a closed annular groove portion 101 that faces the second engagement portion 23 (described later). The groove portion 101 is formed in the circumferential direction of the opening 11a of the first tubular portion 11 (i.e., the opening 10a of the first piping member 10) and accommodates the packing 30. The first engagement portion 13 and the second engagement portion 23 (described later) sandwich the packing 30.

[0037] The radially inner side of the groove portion 101 is exposed to the opening 11a of the first tubular portion 11. The groove portion 101 has a circular annular opposing surface 101a that is planar and extends perpendicular to the tube axis Ax and faces the second bulge portion 22, and a cylindrical side surface 101b that is continuous with the opposing surface 101a and extends in the tube axis direction.

[0038] That is, the end face of the first piping member 10 is composed of a groove portion 101 (opposing surface 101a, side surface 101b) and a bulging portion end face 12a (first abutting surface) that is flat and extends perpendicular to the pipe axis Ax and is continuous with the side surface 101b. The bulging portion end face 12a is located at the tip of the first piping member 10 on the second piping member 20 side in the pipe axis direction.

[0039] The first bulging portion 12 has a first tapered surface 12b on the opposite side of the bulging portion end surface 12a in the axial direction of the pipe. The first tapered surface 12b is a tapered surface whose diameter decreases as it moves away from the bulging portion end surface 12a in the axial direction of the pipe.

[0040] <Second piping component> The second piping member 20 is a pipe member having an internal space 20S and made of a resin material. The second piping member 20 can be made of the same material as the first piping member 10.

[0041] The second piping member 20 has a tubular second tubular portion 21 that is open at both ends, and a second bulge portion 22 that is provided at one end 21E of the second tubular portion 21. In the second piping member 20, the one end 21E of the second tubular portion 21 and the second bulge portion 22 that is provided at this end 21E constitute a second engaging portion 23. Therefore, the second engaging portion 23 is also formed from a polyolefin resin such as a polyethylene resin. In the second piping member 20, the second engaging portion 23 is connected to the first engaging portion 13.

[0042] (Second tubular part) The second tubular portion 21 has a tube main body 211 and a reduced tube portion 212 that is reduced radially inward of the tube main body 211 on one end side of the tube main body 211. That is, in the second tubular portion 21, it is preferable that the inner diameter W21 of the tube main body 211 is larger than the inner diameter W22 of the smallest diameter point of the reduced tube portion 212 (W21>W22), but they may be the same diameter.

[0043] A second recess 20C is formed on the outer peripheral surface of the second tubular portion 21 (the outer peripheral surface 20x of the second piping member 20) at a position overlapping with the tube contraction portion 212 in a field of view perpendicular to the tube axis Ax, and adjacent to the second bulge portion 22. The second recess 20C is formed in the shape of an endless closed ring in the circumferential direction of the second tubular portion 21. The tube contraction portion 212 and the second recess 20C are provided in the second engaging portion 23.

[0044] The inner surface of the second tubular portion 21 (inner surface 20y of the second piping member 20) is composed of surface 20y1, which is the inner surface of the pipe main body 211 and is a surface along the pipe axis Ax, surface 20y2, which is the inner surface of the narrowed pipe portion 212 and is a surface along the pipe axis Ax, and inclined surface 20y3 connecting surface 20y1 and surface 20y2.

[0045] (Second bulge) The second bulging portion 22 has a structure that protrudes in an annular shape radially outward from the second piping member 20 at the reduced pipe portion 212 .

[0046] The second engagement portion 23 has a closed annular convex rib portion 201 that faces the first engagement portion 13. The convex rib portion 201 fits into the concave rib portion 101 of the first piping member 10 in a view along the pipe axis Ax.

[0047] The ridge portion 201 is formed in the circumferential direction of the opening 21a of the second tubular portion 21 (i.e., the opening 20a of the second piping member 20). The outer diameter W23 of the ridge portion 201 is formed to a size that allows it to fit into the recessed ridge portion 101, and is smaller than the outer diameter W13 of the recessed ridge portion 101. This allows the ridge portion 201 to fit into the recessed ridge portion 101. The ridge portion 201 comes into contact with the packing 30 at the connection point between the first piping member 10 and the second piping member 20, and presses the packing 30 in a direction parallel to the pipe axis Ax.

[0048] The inner diameter W24 of the ridge portion 201 is equal to the opening diameter (inner diameter W22 at the reduced tube portion 212) of the second tubular portion 21 (W22 = W24). The ridge portion 201 has a circular facing surface 201a that is flat and extends perpendicular to the tube axis Ax and faces the first engagement portion 13, and a cylindrical side surface 201b that is continuous with the facing surface 201a and extends along the tube axis Ax.

[0049] That is, the end face of the second piping member 20 is composed of a convex rib portion 201 (opposing surface 201a, side surface 201b) and a bulge portion end face 22a (second abutting surface) that is flat and extends perpendicular to the pipe axis Ax and is continuous with the side surface 201b. The opposing surface 201a is located at the tip of the second piping member 20 on the first piping member 10 side in the pipe axis direction. When the convex rib portion 201 is fitted into the concave rib portion 101 of the first piping member 10, it is desirable that the bulge portion end face 22a abuts against the bulge portion end face 12a of the first engagement portion 13 and abuts in a surface-to-surface contact, but a gap may be provided.

[0050] The second bulging portion 22 has a second tapered surface 22b on the opposite side of the bulging portion end surface 22a in the tube axis direction. The second tapered surface 22b is a tapered surface whose diameter decreases as it moves away from the bulging portion end surface 22a in the tube axis direction. The second tapered surface 22b has the same taper as the first tapered surface 12b.

[0051] In FIG. 2, the cross-sectional shape of the ridge portion 201 is shown as being substantially rectangular, but is not limited to this and may be, for example, semicircular or semielliptical.

[0052] As described above, the first engagement portion 13 has a bulging portion end surface 12a facing the second engagement portion 23, and a closed-annular concave streak portion 101 facing the second engagement portion 23 and formed in the circumferential direction of the opening 11a of the first tubular portion 11. The radial inner side of the concave streak portion 101 is exposed to the opening 11a of the first tubular portion 11. The second engagement portion 23 has a bulging portion end surface 22a facing the first engagement portion 13, and a closed-annular convex streak portion 201 facing the first engagement portion 13 and formed in the circumferential direction of the opening 21a of the second tubular portion 21.

[0053] <Packing (sealing material)> The gasket 30 is a closed ring and is accommodated in the concave rib portion 101 at the connection point between the first piping member 10 and the second piping member 20, i.e., the connection point between the first engagement portion 13 and the second engagement portion 23, and is liquid-tightly sandwiched between the first engagement portion 13 and the second engagement portion 23 by being pressed in the pipe axial direction by the convex rib portion 201.

[0054] The packing 30 can be manufactured using a resin material that is commonly used as a packing material, such as ethylene-propylene rubber, isoprene rubber, chloroprene rubber, chlorosulfonated rubber, nitrile rubber, styrene butadiene rubber, chlorinated polyethylene, fluororubber, EPDM (ethylene-propylene-diene rubber), and PTFE (polytetrafluoroethylene).

[0055] Furthermore, the packing 30 may have a reinforcing fabric made of polyamide or nylon (registered trademark) inserted therein.

[0056] Various known shapes of packing 30 can be used. Among them, lip packings (V packing, U packing, L packing, J packing, etc.) and squeeze packings (O-ring, X ring, D ring) specified in JIS B 0116 are preferred as the packing 30. Among them, X-packing is preferred as the packing 30. FIG. 2 shows the use of X-packing as the packing 30.

[0057] Fig. 3 is an enlarged end view of a connection portion of the piping structure 100. Fig. 3 shows a state in which a packing 30 is sandwiched between the first piping member 10 and the second piping member 20. When the convex rib portion 201 of the second piping member 20 is fitted into the concave rib portion 101 of the first piping member 10 and the bulging portion end face 22a of the second piping member 20 is butted against and abuts against the bulging portion end face 12a of the first piping member 10, the packing 30 simultaneously contacts the opposing surface 101a of the concave rib portion 101 and the opposing surface 201a of the convex rib portion 201.

[0058] As shown in Fig. 3, the packing 30, which is an X-packing, has a groove 301 that opens to the inner periphery and continues in the circumferential direction. In the cross-sectional view of Fig. 3, a pair of ribs 302 are formed on both sides of the groove 301. The packing 30 housed in the groove portion 101 is exposed to the flow path FP, which is formed by the internal spaces 10S and 20S and through which the fluid flows, and in this case, the inner periphery side portion, which is the radially inner side and includes the groove 301, is exposed to the flow path FP. In other words, the inner periphery side portion of the packing 30, which includes the groove 301, forms part of the flow path FP.

[0059] In such a piping structure 100, when water flows through the flow path FP, the packing 30 is subjected to a load due to water pressure (symbol F1). At this time, the water in the flow path FP enters the grooves 301 of the packing 30 and applies an isotropic load to the packing 30. As a result, the packing 30 is pushed radially outward at the groove portions 101 under the load (symbol F2).

[0060] Furthermore, the water in the flow path FP spreads the pair of ribs 302, applying a load in a direction that presses one rib 302 against the opposing surface 101a of the concave rib portion 101 and the other rib 302 against the opposing surface 201a of the convex rib portion 201 (symbol F3).

[0061] As described above, when internal pressure from the water in the flow path FP is applied to the packing 30, surface pressure is generated as indicated by the arrows indicated by the symbols F2 and F3, thereby achieving a sealing effect. In the following description, such a seal that obtains surface pressure by utilizing the internal pressure received from the water in the flow path FP may be referred to as a "self-seal."

[0062] 3, in which the convex streak portion 201 fits into the concave streak portion 101, a winding path, a so-called labyrinth structure, is formed in the gap between the convex streak portion 201 and the packing 30, the gap between the first bulge portion 12 and the second bulge portion 22 outside the concave streak portion 101, more specifically, the gap between the side surface 101b and the side surface 201b, and the gap between the bulge end face 12a and the bulge end face 22a. Therefore, with the configuration shown in FIG. 3, an improved sealing effect can be expected compared to when flat surfaces without concave streak portions or convex streak portions are butted together.

[0063] As described above, the packing 30 can obtain both the surface pressure obtained when the first piping member 10 and the second piping member 20 are fastened together, and the surface pressure (self-sealing) generated when the internal pressure from the water in the flow path FP is applied. As a result, the packing 30 is pressed against the wall surface in the space surrounded by the grooved rib portion 101 and the protruding rib portion 201, and a high sealing effect is achieved with a compact piping structure.

[0064] The above-mentioned effect is also achieved when various types of packing having grooves opening to the inner periphery are used. That is, even when the above-mentioned lip packing or squeeze packing is used, a similar sealing effect can be expected as long as the grooves of the packing are exposed to the flow path FP of the piping structure 100.

[0065] <<Jointing materials>> As shown in Figures 1 to 4, the piping structure 100 has a closed-ring-shaped joining member 90 that surrounds and fixes the first bulge portion 12 and the second bulge portion 22 from the outer periphery at the connection point between the first piping member 10 and the second piping member 20, i.e., the connection point between the first engaging portion 13 and the second engaging portion 23.

[0066] As shown in FIG. 1, the joint member 90 has a pair of divided members 91 and 92 formed in a semicircular arc shape, and a pair of fasteners 93 that fasten the divided members 91 and 92 in a connected state.

[0067] The divided member 91 has a storage portion 911 formed in a substantially arcuate shape and having a storage space on its inner circumferential side, and a pair of connecting portions 912 provided at the ends of the storage portion 911. As shown in FIG. 2 , the storage portion 911 has a first abutment tapered surface 911a and a second abutment tapered surface 911b that face each other in the tube axis direction. The first abutment tapered surface 911a and the second abutment tapered surface 911b are symmetrical in shape in the tube axis direction and become increasingly separated from each other in the tube axis direction as they move radially inward. The first abutment tapered surface 911a has a tapered shape similar to that of the first tapered surface 12b of the first bulging portion 12, and the second abutment tapered surface 911b has a tapered shape similar to that of the second tapered surface 22b of the second bulging portion 22.

[0068] As shown in FIG. 1, the divided member 92 has a housing portion 921 formed in a substantially arcuate shape and having a housing space on its inner circumferential side, and a pair of connecting portions 922 provided at the ends of the housing portion 921. As shown in FIG. 2, the housing portion 921 has a first abutting tapered surface 921a and a second abutting tapered surface 921b that face each other in the tube axial direction. The first abutting tapered surface 921a and the second abutting tapered surface 921b are symmetrical in the tube axial direction and gradually move further apart in the axial direction as they extend radially inward. The first abutting tapered surface 921a has a tapered shape similar to that of the first tapered surface 12b of the first bulging portion 12, and the second abutting tapered surface 921b has a tapered shape similar to that of the second tapered surface 22b of the second bulging portion 22. The divided members 91 and 92 may have the same shape.

[0069] 1, the fixture 93 has a bolt 931 and a nut 932 that extend perpendicular to the pipe axis direction. The pair of fixtures 93 extend parallel to each other.

[0070] In such a joining member 90, the first bulge portion 12 and the second bulge portion 22 are sandwiched between the divided members 91 and 92, and a bolt 931 is inserted into the through hole 912a of the connecting portion 912 and the through hole 922a of the connecting portion 922, and locked with a nut 932, thereby surrounding the first bulge portion 12 and the second bulge portion 22 from the outer periphery.

[0071] 2, the first abutment tapered surface 911a of the divided member 91 and the first abutment tapered surface 921a of the divided member 92 abut in surface contact with the first tapered surface 12b of the first bulging portion 12, and the second abutment tapered surface 911b of the divided member 91 and the second abutment tapered surface 921b of the divided member 92 abut in surface contact with the second tapered surface 22b of the second bulging portion 22, and the inner peripheral end portions of the joining member 90 (end portion 91a of the divided member 91 and end portion 92a of the divided member 92) are inserted into the first recess 10C and the second recess 20C. This prevents the joining member 90 from shifting position.

[0072] Furthermore, when the fastener 93 is tightened, the joining member 90, which is in surface contact with the first tapered surface 12b of the first bulging portion 12 at the first contact tapered surfaces 911a, 921a and in surface contact with the second tapered surface 22b of the second bulging portion 22, generates a component force in the pipe axis direction at the contact point with the first bulging portion 12, pressing the first bulging portion 12 toward the second piping member 20, and also generates a component force in the pipe axis direction at the contact point with the second bulging portion 22, pressing the second bulging portion 22 toward the first piping member 10. As a result, the first piping member 10 and the second piping member 20 are pressed against each other in the pipe axis direction and are firmly connected. As a result, as shown in Figure 3, the bulge end surface 12a of the first bulge portion 12 of the first piping member 10 and the bulge end surface 22a of the second bulge portion 22 of the second piping member 20 come into close contact with each other, and the gasket 30 is clamped between the opposing surface 101a of the concave rib portion 101 and the opposing surface 201a of the convex rib portion 201.

[0073] Here, because the first engaging portion 13 and the second engaging portion 23 are made of polyolefin resin, they are prone to thermal shrinkage, which can easily generate loads in the axial direction of the pipe. For this reason, if the first engaging portion 13 and the second engaging portion 23 are connected with a fastener that extends in the axial direction of the pipe, the fastener is likely to loosen due to the load in the axial direction of the pipe. This requires periodic retightening of the fastener, which is time-consuming for maintenance. In contrast, in this embodiment, the first engaging portion 13 and the second engaging portion 23 are connected by a joining member 90 having a structure in which a divided member 91 having a first contact tapered surface 911a that contacts the first tapered surface 12b and a second contact tapered surface 911b that contacts the second tapered surface 22b and a divided member 92 having a first contact tapered surface 921a that contacts the first tapered surface 12b and a second contact tapered surface 921b that contacts the second tapered surface 22b are connected by a fastener 93 that extends perpendicular to the tube axis direction. Therefore, even if a load is generated in the tube axis direction due to thermal contraction of the first engaging portion 13 and the second engaging portion 23, the fastener 93 is not easily affected and is unlikely to loosen. This reduces the effort required for maintenance, such as retightening the fastener 93.

[0074] Although the joining member 90 is shown as being separated into the divided members 91 and 92, this is not limitative. The divided members 91 and 92 may be hinged at one of the joints 912 and 922, and fixed by a fixing device 93 only at the other of the joints 912 and 922.

[0075] 4 to 9, the detailed shape and configuration of the piping structure 100 will be described. FIGS. 4 to 9 are partial end views illustrating the piping structure 100.

[0076] The first piping member 10 and the second piping member 20 have the same shape except for the configuration of the concave rib portion 101 and the convex rib portion 201. Therefore, in the following description, when describing a configuration common to the first piping member 10 and the second piping member 20, the description of one configuration (e.g., the first piping member 10) can be understood by replacing the description of the other configuration (e.g., the second piping member 20).

[0077] (Thickness of the bulging part) 4, in the piping structure 100, the thickness A1 of the first bulging portion 12 in the pipe axial direction is equal to the thickness A2 of the second bulging portion 22 (A1=A2). The thicknesses A1 and A2 may be, for example, 96% or more, 140% or more, or 190% or more of the pipe wall thickness ratio. (Thickness of the bulging part) 4, in the piping structure 100, the thickness A1 of the first bulging portion 12 in the pipe axis direction is equal to the thickness A2 of the second bulging portion 22 (A1=A2). The thicknesses A1 and A2 may be, for example, 10 mm or more, 15 mm or more, or 20 mm or more.

[0078] When the thickness A1 of the first bulge portion 12 and the thickness A2 of the second bulge portion 22 have the above-mentioned relationship, the shape of the joining member 90 can be made plane-symmetrical with respect to a virtual plane perpendicular to the tube axis Ax, and the stress applied by the joining member 90 is well-balanced.

[0079] 5, the thickness A1 of the first bulging portion 12 may be thicker than the thickness A2 of the second bulging portion 22 (A1>A2). In this case, the shapes of the groove portion 101 and the protrusion portion 201 may be adjusted so that the packing 30 is positioned at the center of the first bulging portion 12 and the second bulging portion 22 inside the piping structure (A3=A4).

[0080] (Thickness of recess) 4, the thickness B1 of the first tubular portion 11 (contracted portion 112) at the position of the first recess 10C is preferably equal to or greater than the thickness B2 of the tube main body 111 (B1≧B2). This relationship makes it possible to prevent a decrease in strength of the contracted portion 112.

[0081] (Slope of the recess) 4, the angle θ formed between bottom surface 10C1 of first recess 10C and first tapered surface 12b of first bulge 12 continuing from bottom surface 10C1 may be 30° or more and 80° or less. Angle θ may be 30° or more and 70° or less, or 30° or more and 60° or less. The larger the angle formed by tapered surface 12b, the smaller the axial force applied to the bolt, allowing the bolt diameter to be designed to be smaller.

[0082] If the angle θ is less than 30°, the accommodation portion 921 is less likely to get caught on the first bulging portion 12 when the first piping member 10 and the second piping member 20 are joined using the joining member 90. Therefore, for example, if stress is generated that pulls the first piping member 10 apart in the pipe axis direction, the pull-out force (the force required to pull the first piping member 10 out of the joining member 90) decreases.

[0083] If the angle θ exceeds 80°, stress will be concentrated when the above-mentioned pulling force is generated, making it difficult to disperse the generated stress, which may result in a decrease in strength.

[0084] The angle θ can be defined as the angle formed by an imaginary line L1 that is parallel to the tube axis Ax in the cross section of FIG. 4 and tangent to the bottom surface 10C1, and a tangent line L2 at the center of the first tapered surface 12b.

[0085] By setting the angle θ to the above value, stress is less likely to be concentrated at the intersection R between the first recess 10C and the first bulge 12, and breakage can be suppressed.

[0086] (depth of recess) Furthermore, the radial height Z1 from the inner peripheral surface of the tube main body 211 to the inner peripheral surface of the tube-reducing portion 212 is preferably equal to or greater than the radial height Z2 from the outer peripheral surface of the tube main body 111 to the bottom surface 20C1 of the second recess 20C (Z1≧Z2). This makes it possible to prevent a decrease in strength at the position of the second recess 20C.

[0087] (Position of the groove) It is preferable that the groove 101 does not interfere with (does not overlap with) the first recess 10C in the field of view along the tube axis Ax.

[0088] (depth of grooves, protrusion of ridges) The length C1 of the groove 101 in the axial direction (the length from the opposing surface 101a in the axial direction to the bulge end surface 12a) is greater than the length C2 of the protrusion 201 in the axial direction (the length from the opposing surface 201a in the axial direction to the bulge end surface 22a) (C1>C2). The lengths C1 and C2 should be set taking into consideration the thickness of the packing 30 when it is liquid-tightly sandwiched between the groove 101 and the protrusion 201.

[0089] A length C1 from the opposing surface 101a, which is a first abutment portion that abuts against the packing 30 of the groove portion 101 in the pipe axis direction, to the bulging portion end face 12a, which is the tip of the first piping member 10 on the second piping member 20 side in the pipe axis direction, is longer than a length C3 in the pipe axis direction of the packing 30 (see FIG. 2) before the first engagement portion 13 and the second engagement portion 23 are connected, i.e., in its natural state. As a result, the packing 30, which is housed in the groove portion 101 of the first piping member 10 and abuts against the opposing surface 101a before the first engagement portion 13 and the second engagement portion 23 are connected, can be retracted inward from the bulging portion end face 12a, which is the tip of the first piping member 10 on the second piping member 20 side in the pipe axis direction. Therefore, when connecting the first engagement portion 13 of the first piping member 10 with the packing 30 set in the groove portion 101 to the second engagement portion 23 of the second piping member 20, it is possible to prevent the packing 30 from shifting position or falling off relative to the groove portion 101.

[0090] For example, with the packing 30 set in the recessed streak portion 101, the opposing surface 201a of the convex streak portion 201 at the tip of the second piping member 20 is brought into contact with the bulging end face 12a at the tip of the first piping member 10, and the second piping member 20 is then slid perpendicular to the pipe axis Ax to fit the convex streak portion 201 into the recessed streak portion 101, thereby facilitating the connection work. If the packing 30 protrudes forward beyond the bulging end face 12a at the tip of the first piping member 10, it may come into contact with the convex streak portion 201 and be pushed by the convex streak portion 201, resulting in displacement or detachment relative to the recessed streak portion 101. If the recessed streak portion 101 is exposed on the inner circumferential side of the first tubular portion 11, there is no structure to support the packing 30 from the inner circumferential side of the first tubular portion 11, making the packing 30 particularly susceptible to displacement or detachment. By retracting the gasket 30 of the concave rib portion 101 of the first piping member 10 inward in the pipe axis direction from the bulging portion end face 12a, to facilitate the work, even if the opposing surface 201a of the convex rib portion 201 of the second piping member 20 is abutted against the bulging portion end face 12a of the first piping member 10 and the second piping member 20 is slid to fit the convex rib portion 201 into the concave rib portion 101, the gasket 30 is less likely to come into contact with the second piping member 20 and become displaced or fall off.

[0091] Here, the length C3 of the packing 30 in the pipe axial direction is preferably 200% or less in terms of the pipe wall thickness ratio. On the other hand, the length C1 from the opposing surface 101a of the groove portion 101 to the bulge portion end face 12a at the tip of the first piping member 10 is preferably 60% or more in terms of the pipe wall thickness ratio.

[0092] When the first engagement portion 13 of the first piping member 10 and the second engagement portion 23 of the second piping member 20 are connected, the length (C1-C2) in the pipe axis direction from the opposing surface 101a, which is the first abutment portion that abuts the packing 30 of the recessed rib portion 101 in the pipe axis direction, to the opposing surface 201a, which is the second abutment portion that abuts the packing 30 of the protruding rib portion 201 in the pipe axis direction, is shorter than the length C3 in the pipe axis direction of the packing 30 in its natural state (see FIG. 2) before the first engagement portion 13 and the second engagement portion 23 are connected. As a result, when the first engagement portion 13 and the second engagement portion 23 are connected, the packing 30 arranged between the recessed rib portion 101 and the protruding rib portion 201 is compressed in the pipe axis direction.

[0093] 3, when the packing 30 has a groove 301 on the inner circumferential side, a self-sealing effect can be obtained. In this case, if the pair of ribs 302 are crushed by the convex rib portion 201 so that they come into contact with each other, it may be difficult to apply internal water pressure from inside the groove 301 in a direction that widens the ribs 302, and self-sealing may not occur. Therefore, it is preferable that the lengths C1 and C2 are lengths that do not cause the pair of ribs 302 to come into contact with each other.

[0094] It is preferable that the length (C1-C2) in the pipe axis direction from the opposing surface 101a of the concave rib portion 101 to the opposing surface 201a of the convex rib portion 201 when the first engagement portion 13 and the second engagement portion 23 are connected is set in relation to the length C3 in the pipe axis direction of the packing 30 before the first engagement portion 13 and the second engagement portion 23 are connected so that the compression rate of the packing 30 in the pipe axis direction is 5% to 40%.

[0095] As described above, the length C3 of the packing 30 in the pipe axis direction is preferably 200% or less in terms of the pipe wall thickness ratio. On the other hand, the length (C1-C2) in the pipe axis direction from the opposing surface 101a of the recessed rib portion 101 to the opposing surface 201a of the protruding rib portion 201 is preferably 10% or more in terms of the pipe wall thickness ratio.

[0096] (Protrusion amount of bulge) The first piping member 10 and the second piping member 20 are both configured to have bulging portions (first bulging portion 12, second bulging portion 22) in the contracted pipe portions 112, 212. The amount of radial outward protrusion of the bulging portion is the distance (symbol X) from the outer surface of the pipe main body 211 to the outermost radial portion of the second bulging portion 22.

[0097] On the other hand, when a bulge portion is provided in a tubular portion (first tubular portion 11, second tubular portion 21) that does not have a contracted portion, the protrusion amount of the bulge portion corresponds to the distance Y from the bottom of the second recess 20C to the radial outermost part of the second bulge portion 22.

[0098] That is, in the piping structure 100, by providing a bulging portion in the tubular portion having a contracted portion, the protrusion amount X of the bulging portion can be reduced. As a result, when attempting to improve sealing performance by using a large sealing member in the piping structure, even if the bulging portion of the piping member is made larger to match the size of the sealing member, the outermost dimension of the piping member can be reduced, and a decrease in work efficiency can be suppressed.

[0099] (Gasket fall prevention structure) 6 to 9 are end views showing the structure for preventing the packing from falling off. When the groove portion 101 is exposed on the inner circumferential side of the first tubular portion 11, as in the case of the groove portion 101 described above, there is no structure for supporting the packing 30 from the inner circumferential side of the first tubular portion 11, and therefore the packing 30 is prone to displacement or falling off. For this reason, the first piping member 10 and the second piping member 20 may be configured as shown in the following Figs. 6 to 9.

[0100] 6, the first piping member 10 may have support recesses 102 at the corners on the outer circumferential side of the grooved streak portion 101, into which a part of the packing 30 is inserted to support the packing 30. The support recesses 102 are provided in the circumferential direction of the first piping member 10 along the corners of the grooved streak portion 101.

[0101] The support recesses 102 may be provided around the entire circumferential circumference of the first piping member 10, or may be scattered at equal intervals in the circumferential direction of the first piping member 10. When the support recesses 102 are scattered at multiple locations, the multiple support recesses 102 may be the same size or different sizes.

[0102] In this case, it is desirable that the portion 30 a of the packing 30 inserted into the support recess 102 be molded into the same shape as the cross-sectional shape of the support recess 102 .

[0103] Also, as shown in Figure 7, the first piping member 10 may have a first support protrusion 103 at the inner end of the groove portion 101 (the end of the groove portion 101 on the pipe axis Ax side) that protrudes into the inside of the groove portion 101 and supports the gasket 30.

[0104] Similarly, as shown in Figure 8, the first piping member 10 may have a first support protrusion 104 at the tip end of the groove portion 101 (the end of the groove portion 101 on the side of the bulge portion end face 12a) that protrudes into the groove portion 101 and supports the gasket 30.

[0105] The first support protrusions 103, 104 may be provided all around the circumference of the first piping member 10, or may be provided discretely. In addition, the groove portion 101 may have both of the first support protrusions 103, 104 formed therein.

[0106] Furthermore, as shown in Figure 9, the second tubular portion 21 may have a second support protrusion 202 at the tip end of the convex rib portion 201, more specifically, at the inner end of the convex rib portion 201, which supports the packing 30 from the inner side.

[0107] The second support protrusions 202 may be provided around the entire circumferential circumference of the second tubular portion 21, or may be scattered at equal intervals in the circumferential direction of the second piping member 20. When the second support protrusions 202 are scattered at multiple locations, the multiple second support protrusions 202 may be the same size or different sizes.

[0108] The first piping member 10 and the second piping member 20 have a structure for preventing them from falling off, which prevents the packing 30 from shifting out of position, improving work efficiency.

[0109] [Prefabricated piping] 10 and 11 are explanatory diagrams of an example of a prefabricated piping system having the above-described piping structure.

[0110] 10 is a cross-sectional view of a piping member 50 having a joint 40. The piping member 50 has the above-mentioned first piping member 10, the joint 40, a piping member 41, and a socket 42, which are connected in this order in the axial direction. The joint 40 connects the first piping member 10 and the piping member 41. The socket 42 is located at the end of the piping member 41.

[0111] The first piping member 10 constituting the piping member 50 has a first bulging portion 12 with a groove portion 101 at one end 11E1 of the first tubular portion 11, and is connected to the fitting 40 at the other end 11E2 of the first tubular portion 11. The method of connecting the first tubular portion 11 and the fitting 40 can be selected according to the properties of the materials of the first tubular portion 11 and the fitting 40, such as fusion bonding or adhesive bonding.

[0112] The joint 40 is a piping member (pipe joint) made of a resin material, and is connected to the first piping member 10 in order to route the piping member along an intended path. As the material of the joint 40, the resin material described above as the material of the first piping member 10 can be used.

[0113] The piping member 41 is a straight pipe made of a resin material. As the material of the piping member 41, the resin material mentioned above as the material of the first piping member 10 can be used.

[0114] The socket 42 is a so-called electric fusion joint and has a heating wire inside. The socket 42 has a terminal 42x connected to the heating wire. The socket 42 is connected to the piping member 41.

[0115] In the piping member 50, the internal space of the first piping member 10, the internal space of the fitting 40, the internal space of the piping member 41, and the internal space of the receiving portion 42 are continuous and communicate from the opening 10a at the end of the first piping member 10 to the opening 42a at the end of the receiving portion 42.

[0116] Although FIG. 10 shows a curved pipe as the joint, various known joints can be used.

[0117] At the connection point between the first piping member 10 and the fitting 40 and at the connection point between the fitting 40 and the piping member 41, a bead B of molten resin is formed continuously in the circumferential direction on the inner and outer circumferential surfaces of the pipe. On the inner circumferential side of the first tubular section 11, it is preferable that the radial height Z1 from the inner circumferential surface of the pipe main body 111 to the inner circumferential surface of the tube-reducing section 112 is the same as or lower than the height Z3 of the bead B. This makes it possible to suppress pressure loss due to the tube-reducing section 112.

[0118] 11 is a cross-sectional view showing an example of a prefabricated piping 200 of this embodiment. In the prefabricated piping 200, a fitting 40 is connected to the first piping member 10 of the above-mentioned piping structure 100, and a tee 60 is connected to the second piping member 20. A bead B is formed at the connection point between the second piping member 20 and the tee 60.

[0119] Tee 60 is a piping member (pipe joint) made of a resin material, and is connected to second piping member 20 to branch the piping member into intended paths. Tee 60 has a main pipe 61 and a branch pipe 62 that is connected to and communicates with main pipe 61.

[0120] 11 is an example, and various known configurations can be used as joints. Also, a known configuration for connecting to a pipe may be connected to the end of the joint.

[0121] In the prefabricated piping 200, for example, the first piping member 10 is provided to equipment (e.g., a pump, a water heater, other prefabricated piping, etc.) installed at the construction site, the second piping member 20 is used as the connecting piping member, and the first bulge portion 12 and the second bulge portion 22 are butted together and fixed with a joining member 90, thereby making it possible to easily perform piping work at the construction site.

[0122] In addition, because there is no need to fabricate the bulge at the construction site, butt welding at the construction site is unnecessary, and therefore, no bead that would accompany butt welding is formed near the bulge of the prefabricated pipe.

[0123] The piping structure having the above-described configuration can stably ensure sealing performance without excessively increasing the size, and can also prevent a decrease in the efficiency of assembly work.

[0124] Furthermore, the prefabricated piping structure described above is easy to install and ensures stable sealing performance. It also makes it possible to prevent a decrease in the efficiency of the assembly work of the piping structure.

[0125] [Second embodiment] Fig. 12 is a schematic perspective view of a piping structure 150 according to a second embodiment of the present invention, and is a cross-sectional view corresponding to Fig. 4. In the second embodiment, components common to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0126] In the first embodiment, the first tubular portion 11 has a narrowing portion 112, and the inner surface 10y of the first piping member 10 is composed of a surface 10y1, a surface 10y2, and an inclined surface 10y3. However, in the piping structure 150 of the second embodiment, the first piping member 160 does not have a narrowing portion 112, the outer diameter of the first tubular portion 161 is a constant outer diameter, and the inner surface 160y of the first piping member 160, excluding the groove portion 101, is a constant diameter.

[0127] Similarly, in the first embodiment, the second tubular portion 21 has a narrowing portion 212, and the inner surface 20y of the second piping member 20 is composed of surface 20y1, surface 20y2, and inclined surface 20y3, but in the piping structure 150 of the second embodiment, the second piping member 170 does not have a narrowing portion 212, the outer diameter of the second tubular portion 171 is a constant outer diameter, and the inner surface 170y of the second piping member 170 is a constant diameter.

[0128] [Third embodiment] Fig. 13 is a schematic cross-sectional view of a piping structure 250 according to a third embodiment of the present invention, and is a cross-sectional view corresponding to Fig. 2. In the third embodiment, components common to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0129] As shown in FIG. 13 , in the piping structure 250, the opposing surface 101 a and the side surface 101 b of the groove portion 101 of the first piping member 10 and the bulging portion end surface 12 a of the first bulging portion 12 are formed by a first metal plate 410 made of a metal material. The first metal plate 410 has a portion forming the opposing surface 101 a, a portion forming the side surface 101 b, and a portion forming the bulging portion end surface 12 a integrally formed. The first piping member 10 is formed by insert molding the first metal plate 410 with a resin material 411 during injection molding or pipe end thermal processing. For example, when injection molding the resin material of the first piping member 10, the first metal plate 410 is set in a mold, and molten resin material is injected into the mold in this state, thereby integrating the first metal plate 410 with the resin material 411. The first metal plate 410 may be bonded to the molded resin material 411 with an adhesive.

[0130] Examples of the metal material for the first metal plate 410 include aluminum alloy, SUS (stainless steel), magnesium, and the like.

[0131] In the first piping member 10 of the piping structure 250, the portion forming the opposing surface 101a, the portion forming the side surface 101b, and the portion forming the bulge end surface 12a are made of the first metal plate 410, which allows for increased dimensional accuracy of the opposing surface 101a, the side surface 101b, and the bulge end surface 12a. This eliminates the need for long-term pressure application during injection molding, slow cooling in the mold, or cutting in a separate process after molding, which are required to accurately form these components with resin, thereby improving productivity. Furthermore, by forming the opposing surface 101a, the side surface 101b, and the bulge end surface 12a of the first piping member 10 from the first metal plate 410, the mold release method can be simplified, which also improves productivity. Furthermore, by forming the opposing surface 101a, the side surface 101b, and the bulging portion end surface 12a of the first piping member 10 from the first metal plate 410, deformation of these surfaces due to creep caused by internal pressure or thermal compression can be suppressed.

[0132] In the piping structure 250, the opposing surface 201a and the side surface 201b of the protruding strip portion 201 of the second piping member 20 and the bulging portion end surface 22a of the second bulging portion 22 are formed by a second metal plate 420 made of a metal material. In the second metal plate 420, a portion forming the opposing surface 201a, a portion forming the side surface 201b, and a portion forming the bulging portion end surface 22a are integrally formed. The second piping member 20 is formed by insert molding the second metal plate 420 with a resin material 421 during injection molding or pipe end thermal processing. For example, when injection molding the resin material 421 of the second piping member 20, the second metal plate 420 is set in a mold, and in this state, molten resin material is injected into the mold, thereby integrating the second metal plate 420 with the resin material 421. The second metal plate 420 may be bonded to the molded resin material 421 with an adhesive.

[0133] As the metal material of the second metal plate 420, the same metal material as the metal material of the first metal plate 410 can be used.

[0134] In the second piping member 20 of the piping structure 250, the portion forming the opposing surface 201a, the portion forming the side surface 201b, and the portion forming the bulge end surface 22a are made of the second metal plate 420, which allows for increased dimensional accuracy of the opposing surface 201a, the side surface 201b, and the bulge end surface 22a. This eliminates the need for long-term pressure application during injection molding, slow cooling in the mold, or cutting in a separate process after molding, which are required to accurately form these components from resin, thereby improving productivity. Furthermore, by forming the opposing surface 201a, the side surface 201b, and the bulge end surface 22a of the second piping member 20 from the second metal plate 420, the mold release method can be simplified, thereby also improving productivity. Furthermore, by forming the opposing surface 201a, the side surface 201b, and the bulging portion end surface 22a of the second piping member 20 from the second metal plate 420, deformation of these surfaces due to creep caused by internal pressure or thermal compression can be suppressed.

[0135] The piping structure 250 can improve the dimensional accuracy of the opposing surfaces 101a and side surfaces 101b of the recessed rib portions 101 of the first piping member 10 and the bulging portion end surfaces 12a of the first bulging portions 12 over a long period of time without reducing productivity, and can improve the dimensional accuracy of the opposing surfaces 201a and side surfaces 201b of the protruding rib portions 201 of the second piping member 20 and the bulging portion end surfaces 22a of the second bulging portions 22 over a long period of time without reducing productivity. Therefore, the piping structure 250 can suppress a decrease in the watertightness of the packing 30 between the first piping member 10 and the second piping member 20 over a long period of time without reducing productivity.

[0136] In the first piping member 160 of the second embodiment, similarly to the first piping member 10 of the third embodiment, the opposing surface 101a and the side surface 101b of the concave streak portion 101 and the bulging portion end surface 12a of the first bulging portion 12 may be formed from the first metal plate 410. In the second piping member 170 of the second embodiment, similarly to the second piping member 20 of the third embodiment, the opposing surface 201a and the side surface 201b of the convex streak portion 201 and the bulging portion end surface 22a of the second bulging portion 22 may be formed from the second metal plate 420.

[0137] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on the design, specifications, etc., without departing from the spirit of the present invention. [Explanation of symbols]

[0138] 10,160...First piping member, 10C...First recess, 11,161...First tubular part, 11a, 21a...Opening, 11E, 21E...One end, 12...First bulge, 12a...Bulge part end surface (first abutting surface), 1 2b...first tapered surface, 13...first engagement part, 20,170...second piping member, 20C...second recessed part, 21,171...second tubular part, 22...second bulging part, 22a...bulging part end surface (second abutting surface), 22b...second Tapered surface, 23...second engaging portion, 30...packing (sealing member), 40...joint, 90...jointing member, 91, 92...dividing member, 91a, 92a...end portion, 93...fixing device, 100, 150, 250...piping structure, 101...concave portion, 201...convex portion, 410...first metal plate, 420...second metal plate, 911a, 921a...first abutting tapered surface, 911b, 921b...second abutting tapered surface, 200...prefabricated piping, FP...flow path.

Claims

1. a first piping member having a first tubular portion having a tubular shape with both ends open and a first bulging portion provided at one end of the first tubular portion, the one end of the first tubular portion and the first bulging portion constituting a first engaging portion formed of a polyolefin-based resin; a second piping member having a second tubular portion having both ends open and a second bulging portion provided at one end of the second tubular portion, the one end of the second tubular portion and the second bulging portion constituting a second engaging portion formed of a polyolefin resin, and the second engaging portion being connected to the first engaging portion; a closed-ring seal member that is liquid-tightly sandwiched between the first engaging portion and the second engaging portion at a connection point between the first engaging portion and the second engaging portion; a closed-ring joining member that surrounds and fixes the first bulge portion and the second bulge portion from an outer circumferential side at the connecting portion, the first engaging portion has a first abutting surface facing the second engaging portion, and a closed annular recessed portion facing the second engaging portion and formed in a circumferential direction of the opening of the first tubular portion, the second engaging portion has a second abutting surface that faces the first engaging portion and abuts against the first abutting surface, the sealing member is accommodated in the groove portion, and an inner circumferential side thereof is exposed to flow paths in the first piping member and the second piping member, the first bulging portion has a first tapered surface on the opposite side to the first abutting surface, the second bulging portion has a second tapered surface on the opposite side to the second abutting surface, The joining member is a piping structure in which a plurality of divided members, each having a first abutment tapered surface that abuts the first tapered surface and a second abutment tapered surface that abuts the second tapered surface, are connected by fasteners extending perpendicular to the pipe axis direction, thereby tightly adhering the first abutment surface and the second abutment surface and sandwiching the sealing member between the groove portion and the second engagement portion.

2. the second engaging portion has a closed annular convex portion that faces the first engaging portion and is formed in a circumferential direction of the opening of the second tubular portion and that fits into the concave portion, The piping structure according to claim 1 , wherein the sealing member is sandwiched between the ridge portion and the groove portion.

3. a first metal plate that forms the first abutting surface of the first engagement portion and the recessed streak portion; a second metal plate that forms the second abutting surface of the second engaging portion and the protruding strip portion; The piping structure according to claim 2 ,

4. the first engaging portion has a first recess formed in the outer circumferential surface of the first tubular portion adjacent to the first bulging portion in the circumferential direction, the second engaging portion has a second recess formed in the outer circumferential surface of the second tubular portion adjacent to the second bulging portion in the circumferential direction, The piping structure according to claim 1 , wherein an inner peripheral end of the joining member is inserted into the first recess and the second recess.

5. The piping structure according to any one of claims 1 to 4, A prefabricated pipe in which a fitting made of a resin material is connected to at least one of the other end of the first tubular portion and the other end of the second tubular portion.

Images