Pipe fittings, piping structures, manifold pipe fittings, rain gutters, and methods for manufacturing pipe fittings

Abstract

The objective is to provide pipe fittings, manifold pipe fittings, rain gutters, and methods for manufacturing pipe fittings. [Solution] The pipe joint A has a curved pipe section 1 having a flow path inside and openings at both ends, an annular first connecting section 2 surrounding the opening at one end of the curved pipe section 1, and an annular second connecting section 3 surrounding the opening at the other end of the curved pipe section 1. It is a resin integral molded product and has a parting line from the molding process in the middle of the curved pipe section 1. It is preferable that the cross section of the curved pipe section 1 including the parting line is elliptical. It is preferable that the first connecting section 2 and the second connecting section 3 are connecting sections for connecting pipes with opposing ends.

Description

[Technical Field]

[0001] This invention relates to pipe fittings, piping structures, manifold pipe fittings, rain gutters, and methods for manufacturing pipe fittings. [Background technology]

[0002] Conventionally, a resin pipe fitting called an S-socket has been known for use as a countermeasure against misalignment in drainage systems, as described in Non-Patent Document 1 below. Furthermore, a pipe fitting called an S-socket for drainage piping of rain gutters is known, as described in Non-Patent Document 2 below. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] FUNEN Across Co., Ltd. FUNEN General Catalog VOL.21, P17, P46, August 2023 <URL:https: / / funen.co.jp / wp01 / wpcontent / themes / funen / assets / download / catalog / catalog.pdf> [Non-Patent Document 2] Panasonic Housing Solutions Co., Ltd. Large-scale rain gutter high-drainage system catalog VP VU75 VP100 VP125, P5, P9, P12, June 2022 <URL:https: / / esctlg.panasonic.biz / iportal / CatalogViewInterfaceStartUpAction. do?method=startUp&mode=PAGE&catalogCategoryId=&catalogId=6236880000&pageGroupId=&volumeID=PEWJ0001&designID=> [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The aforementioned pipe fitting, referred to as an S-socket, is an S-shaped pipe fitting, consisting of a curved pipe section made of an S-shaped pipe and cylindrical socket sections formed at one or both ends of the curved pipe section. This pipe fitting is used to connect pipes by inserting the end of the pipe into the socket section at the end, while absorbing slight misalignments of the pipe.

[0005] To manufacture a pipe fitting called an S-socket, a mold is used that has a molded cavity with a shape corresponding to the outer shape of the pipe fitting. A core is placed in the molded cavity, resin is injected into the molded cavity, and after the resin hardens, the mold is removed to obtain the pipe fitting. When molding a pipe fitting using a mold and cores, one core is inserted straight into the molding cavity from the outside of one of the receiving ends of the pipe fitting, and the other core is inserted straight into the molding cavity from the outside of the other receiving end. The cores are then inserted straight into the center of the molding cavity, and the cores are aligned so that their tips abut each other in the center, after which resin is injected into the molding cavity.

[0006] In conventional resin molding using the aforementioned mold and core, two cores are used: one for molding one socket and approximately half of the curved pipe section connected to this socket, and another for molding the other socket and approximately half of the curved pipe section connected to this socket. In conventional technology, because these two cores are positioned by moving them in a straight line within the molding cavity, a linear step is inevitably created in the pipe wall along the boundary between the two cores that form approximately half of the curved pipe section. When a straight step occurs in the pipe wall of a curved section, this step protrudes towards the flow path side of the curved section, which can lead to a decrease in the quality of the pipe joint.

[0007] In view of the circumstances described above, the present invention aims to provide a pipe fitting of the S-socket type manufactured by resin molding using a mold and a core, which has a structure that does not have steps or other protrusions on the flow path side, a piping structure using the same, and a method for manufacturing the said pipe fitting. Furthermore, the present invention aims to provide a manifold pipe joint equipped with the aforementioned pipe joint and a rain gutter. [Means for solving the problem]

[0008] To solve the aforementioned problems, the present invention proposes the following embodiments. "1" The pipe joint according to this embodiment has a curved pipe section having a flow path inside and openings at both ends, an annular first connecting section surrounding the opening at one end of the curved pipe section, and an annular second connecting section surrounding the opening at the other end of the curved pipe section, and is a resin integrally molded product, and is characterized by having a parting line from the molding process in the middle of the curved pipe section.

[0009] In this form of pipe joint, there is a parting line without a step in the middle of the curved pipe section, and the parting line does not reach the first or second connection section. Therefore, compared to a structure in which a step caused by the parting line reaches the first or second connection section, drainage and accumulation of dust are less likely to occur, and water flow is not obstructed. Furthermore, since the axes of the first and second connection points are misaligned, this misalignment can be used to connect the pipes even if the pipes to be connected to the first connection point and the pipes to be connected to the second connection point are misaligned relative to each other, while absorbing the misalignment.

[0010] "2" In the pipe joint according to this embodiment, a configuration can be adopted in which the cross-section including the parting line of the curved pipe portion is elliptical.

[0011] A parting line exists in the middle of the curved pipe section, and the cross-section including the parting line is elliptical. This makes it easier to remove the core that is inserted into the molded cavity when manufactured by resin molding.

[0012] "3" In the pipe joint according to this embodiment, a configuration can be adopted in which at least one of the first connection part and the second connection part is a connection part for connecting pipes with opposing ends.

[0013] In the pipe joint, the first connection part and the second connection part can each be used for pipe connection, but for the pipes connected to the first connection part and the pipes connected to the second connection part, the direction in which their ends face each other can be selected.

[0014] In the pipe joint according to the fourth aspect, a configuration can be adopted in which the angle formed by the pipe axis of the first connection part and the pipe axis of the second connection part is 135° or more.

[0015] In the pipe joint, the first connection part and the second connection part can each be used for pipe connection, but as the pipes connected to the first connection part and the pipes connected to the second connection part, it can be used for the connection of pipes in which the angle formed by their pipe axes is 135° or more.

[0016] In the pipe joint according to the fifth aspect, a configuration can be adopted in which the inclination angle of the surface including the parting line with respect to the pipe axis of the first connection part and the inclination angle with respect to the pipe axis of the second connection part are both less than 90°.

[0017] In the pipe joint, the first connection part and the second connection part can each be used for pipe connection, but as the pipes connected to the first connection part and the pipes connected to the second connection part, it can be used for the connection of pipes in which the angle formed by their pipe axes is less than 90°.

[0018] In the pipe joint according to the sixth aspect, the first connection part is positioned above and the second connection part is positioned below, the openings of the first connection part and the second connection part are horizontal, and when the cross-section along the plane including the pipe axis of the first connection part, the central axis of the curved pipe part, and the pipe axis of the second connection part is taken as the longitudinal cross-section of the first connection part, the curved pipe part, and the second connection part, one end of the parting line is at the boundary position between the lower end side of the first connection part and the curved pipe part and is located on the side of the curved pipe part, and the other end of the parting line is at the boundary position between the upper end side of the second connection part and the curved pipe part and is located on the side of the curved pipe part. A configuration can be adopted.

[0019] "7" The piping structure according to this embodiment is characterized by comprising a pipe joint according to this embodiment and a pipe or drainage member to which the pipe joint is connected.

[0020] "8" The manifold pipe joint according to this embodiment has a curved pipe section having a flow path inside and openings at both ends, an annular first connecting section surrounding the opening at one end of the curved pipe section, and an annular second connecting section surrounding the opening at the other end of the curved pipe section, and is a resin integrally molded product, and the pipe joint having a parting line from the molding process in the middle of the curved pipe section is connected via a single pipe to a part of either an upper connecting pipe, an intermediate pipe connected to the upper connecting pipe, or a lower connecting pipe connected to the intermediate pipe.

[0021] In a manifold pipe fitting equipped with the pipe fitting according to this embodiment, a parting line exists in the middle of the curved pipe section of the pipe fitting, and the parting line does not reach the first connection part or the second connection part. Therefore, compared to a structure in which a step caused by the parting line reaches the first connection part or the second connection part, drainage and accumulation of dust are less likely to occur, and the flow of water is not obstructed. Accordingly, in the applied manifold pipe fitting, a structure is provided in which the accumulation of water and dust is less likely to occur in the part of the pipe fitting connected via a single pipe. Furthermore, since the first and second connection points of the pipe joint are offset from each other by their axial positions, this offset can be used to absorb the misalignment and allow for pipe connection even if the pipe to be connected to the first connection point and the pipe to be connected to the second connection point are misaligned relative to each other.

[0022] "9" The rain gutter according to this embodiment is a rain gutter comprising an eaves gutter, an upper drain member installed on the bottom plate of the eaves gutter, a lower drain member connected to the upper drain member, and a downpipe connected to the lower drain member, wherein the downpipe has a curved pipe section having a flow path inside and openings at both ends, an annular first connecting section surrounding the opening at one end of the curved pipe section, and an annular second connecting section surrounding the opening at the other end of the curved pipe section, is a resin integral molded product, and a pipe joint having a parting line from the molding process in the middle of the curved pipe section is connected between the lower drain member and the downpipe.

[0023] In this configuration of rain gutters, even if the axes of the upper and lower drain members are misaligned with the axis of the downpipe, the pipe joint can absorb the misalignment and connect the rain gutter and the downpipe. Furthermore, if the connection is made using a pipe joint with a parting line in the middle of the curved section, there are fewer factors that obstruct the flow inside the curved section, making it possible to provide a rain gutter that is less likely to experience a decrease in drainage performance.

[0024] "10" The manufacturing method of the pipe joint according to this embodiment is a resin integral molded product having a curved pipe section having a flow path inside and openings at both ends, an annular first connecting section surrounding the opening at one end of the curved pipe section, and an annular second connecting section surrounding the opening at the other end of the curved pipe section, and when manufacturing a pipe joint having a parting line during molding in the middle of the curved pipe section by resin molding using a mold having a molding cavity and a core inserted into the molding cavity, a base for molding the first connecting section and the portion of the curved pipe section from the first connecting section to the middle of the curved pipe section are molded in the molding cavity. The method is characterized by using a first core having a curved extension for forming a second connecting portion within the molded cavity, a second core having a curved extension for forming a portion of the curved pipe portion that continues from the second connecting portion within the molded cavity, inserting and positioning the first core and the second core into the molded cavity while rotating them in a direction along the curved shape of the extension, bringing the tip of the extension of the first core and the tip of the extension of the second core together inside the molded cavity, and then injecting resin into the molded cavity to form the structure.

[0025] According to the manufacturing method of this embodiment, a resin integral molded product can be manufactured which has a curved pipe section having a flow path inside and openings at both ends, an annular first connecting section surrounding the opening at one end of the curved pipe section, and an annular second connecting section surrounding the opening at the other end of the curved pipe section, and which has a parting line formed during molding in the middle of the curved pipe section. Furthermore, a manufacturing method can be provided which allows for easy extraction of the first core and the second core from the molded cavity.

[0026] "11" In the manufacturing method of this embodiment, the first connecting portion is positioned above and the second connecting portion is positioned below, with the openings of the first connecting portion and the second connecting portion facing sideways, and the cross section along the plane containing the pipe axis of the first connecting portion, the central axis of the curved pipe portion, and the pipe axis of the second connecting portion is the vertical cross section of the first connecting portion, the curved pipe portion, and the second connecting portion, it is preferable that one end of the parting line is located at the boundary between the lower end of the first connecting portion and the curved pipe portion, on the side of the curved pipe portion, and the other end of the parting line is located at the boundary between the upper end of the second connecting portion and the curved pipe portion, on the side of the curved pipe portion. [Effects of the Invention]

[0027] In this form of pipe joint, there is a parting line without a step in the middle of the curved pipe section, and the parting line does not reach the first or second connection section. Therefore, compared to a structure in which a step caused by the parting line reaches the first or second connection section, drainage and accumulation of dust are less likely to occur, and water flow is not obstructed. Furthermore, since the axes of the first and second connection points are misaligned, this misalignment can be used to connect the pipes even if the pipes to be connected to the first connection point and the pipes to be connected to the second connection point are misaligned relative to each other, while absorbing the misalignment. [Brief explanation of the drawing]

[0028] [Figure 1] A perspective view showing an S-socket type pipe fitting according to the first embodiment of the present invention. [Figure 2] A perspective view showing a portion of the pipe joint in a longitudinal section. [Figure 3] A partial cross-sectional view of the pipe joint. [Figure 4] This is a vertical cross-sectional view showing the position where the core is inserted into the pipe fitting when the pipe fitting is manufactured by resin molding using a mold and a core. [Figure 5] A longitudinal cross-sectional view showing the location of the parting line formed in the pipe joint. [Figure 6]A perspective view showing an example of a first core used when manufacturing pipe fittings by resin molding using a mold and core. [Figure 7] A perspective view showing an example of a second core used when manufacturing pipe fittings by resin molding using a mold and core. [Figure 8] A partial cross-sectional view showing a pipe fitting formed in the mold cavity using the first and second cores, with the first and second cores removed from the mold cavity. [Figure 9] A perspective view showing the shape of the tip of the extension formed on the core. [Figure 10] A perspective view showing the shape of the base end of the extension formed on the core. [Figure 11] A cross-sectional view showing an example of a pipe fitting in a comparative example. [Figure 12] A cross-sectional view showing another example of a pipe fitting in the comparative example. [Figure 13] A longitudinal cross-sectional view illustrating a comparison between the parting line formed in the pipe joint of the first embodiment and the parting line formed in a conventional pipe joint. [Figure 14] A perspective view showing the stepped portion formed in a conventional pipe fitting known as an S-socket. [Figure 15] A cross-sectional view illustrating a second embodiment in which a pipe joint is applied to a manifold pipe joint. [Figure 16] A partial cross-sectional view showing the main part of the manifold joint. [Figure 17] This is a plan view showing a second embodiment in which an S-socket type pipe fitting is applied to the same manifold pipe fitting. [Figure 18] A side view showing a third embodiment in which pipe fittings are applied to the piping of a toilet. [Figure 19] A side view showing a fourth embodiment in which a pipe fitting is applied to the drainage pipe of a rain gutter. [Modes for carrying out the invention]

[0029] (First Embodiment) The pipe joint of the first embodiment according to the present invention will be described below with reference to Figures 1 to 13. The pipe fitting A according to this embodiment has the shape shown in Figures 1 to 5 and is a pipe fitting called an S-socket, which is roughly S-shaped in side view, for connecting various types of pipes. The pipe joint A of this embodiment has a roughly S-shape when viewed from the side, and includes a curved pipe section 1 having a flow path inside, a first socket section 2 which is a cylindrical (annular) first connecting section formed at one end of the curved pipe section 1, and a second socket section 3 which is a cylindrical (annular) second connecting section formed at the other end of the curved pipe section 1. The pipe joint A is made of a single molded resin product. Furthermore, either the first or second connection portion may not be a socket, but rather a socket that is inserted into a socket provided by another drainage member such as a joint, in which case the circumferential step portion 1g described later will not be formed. Before describing the details of the shape of pipe joint A, the desirable materials for constructing pipe joint A are described below.

[0030] "Regarding the constituent materials of pipe joint A" Pipe fitting A contains a resin composition (A) comprising a polyvinyl chloride resin and a heat absorbent. That is, pipe fitting A is manufactured by molding the resin composition (A). Typically, pipe fitting A is manufactured by injection molding the resin composition (A). The pipe fitting A may be a single-layer structure made entirely of resin composition (A), or it may be a multi-layer structure consisting of multiple layers. In the case of a multi-layer structure, it is sufficient if any of the layers are made of resin composition (A). For example, if the pipe fitting A has a three-layer structure consisting of a surface layer, an intermediate layer, and an inner layer, the intermediate layer may be made of resin composition (A). The resin composition (A) constituting the pipe fitting A preferably does not contain thermally expandable graphite.

[0031] [Resin composition (A)] Examples of polyvinyl chloride resins included in resin composition (A) include polyvinyl chloride homopolymers; copolymers of vinyl chloride monomer and other monomers having unsaturated bonds copolymerizable with the vinyl chloride monomer; and graft copolymers obtained by graft copolymerizing vinyl chloride monomer with a polymer other than a polyvinyl chloride resin. One type of polyvinyl chloride resin may be used alone, or two or more types may be used in combination. The polyvinyl chloride resin may be further chlorinated. Examples of methods for chlorinating the polyvinyl chloride resin include thermal chlorination and photochlorination.

[0032] Other monomers having unsaturated bonds that can copolymerize with the vinyl chloride monomer include, for example, α-olefins such as ethylene, propylene, and butylene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as butyl vinyl ether and cetyl vinyl ether; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl acrylate; aromatic vinyls such as styrene and α-methylstyrene; and N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide. The other monomers may be used individually or in combination of two or more.

[0033] Examples of polymers used for graft copolymerization of the vinyl chloride monomer include ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-carbon monoxide copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate-carbon monoxide copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, acrylonitrile-butadiene copolymer, polyurethane, chlorinated polyethylene, and chlorinated polypropylene. These polymers may be used individually or in combination of two or more.

[0034] The polyvinyl chloride resin may be crosslinked. Examples of methods for crosslinking the polyvinyl chloride resin include adding a crosslinking agent and a peroxide, irradiating with an electron beam, and using a water-crosslinkable material.

[0035] The average degree of polymerization of the polyvinyl chloride resin is preferably 400 to 1600, and more preferably 600 to 1400. Here, the average degree of polymerization is the average degree of polymerization measured in accordance with JIS K-6721 "Test Method for Vinyl Chloride Resin" using a resin obtained by dissolving the polyvinyl chloride resin in tetrahydrofuran (THF), removing insoluble components by filtration, and then drying and removing the THF from the filtrate. If the average degree of polymerization of the polyvinyl chloride resin is above the lower limit, the mechanical strength can be sufficiently increased, and if it is below the upper limit, sufficient moldability can be ensured.

[0036] The heat absorbent contained in resin composition (A) is a compound that has an endothermic effect when heated and suppresses the rise in temperature. For example, a compound that undergoes an endothermic reaction such as a dehydration reaction when heated can be used as the heat absorbent. Examples of compounds that undergo a dehydration reaction when heated include inorganic hydroxides such as magnesium hydroxide, aluminum hydroxide, kaolin-based minerals (kaolinite, halloysite, dickite), and hydrotalsalcite, as well as water-absorbing inorganic compounds such as sepiolite, bentonite, montmorillonite, talc, mica, quartz, zeolite, wollastonite, and nepheline cyanite. Hereinafter, inorganic hydroxides and inorganic compounds that undergo a dehydration reaction when heated will be collectively referred to as "heat-dehydrating compounds." In the case of heat-dehydrating compounds, the temperature rise can also be suppressed by the latent heat of vaporization of water produced by the dehydration reaction. Among heat-dehydrating compounds, magnesium hydroxide undergoes a dehydration reaction at temperatures above 300°C. Therefore, when magnesium hydroxide is used as a heat absorber, the dehydration reaction can be suppressed when molding the resin composition (A) to produce the pipe fitting A. Among the heat dehydration type compounds, since the dehydration reaction of aluminum hydroxide occurs at around 200°C, when using aluminum hydroxide as a heat absorbent, the heat transmitted to the pipe joint A during a fire can be absorbed quickly. Therefore, it is possible to further suppress the deformation of the pipe joint A and the impairment of its fire resistance before the pipe material 20 (the pipe for the first riser) thermally expands.

[0037] Among the heat dehydration type compounds, hydrotalcite is a kind of mineral represented by chemical name magnesium·aluminum·hydroxide·carbonate·hydrate, such as Mg6Al2(OH)16CO3·4H2O, and is a layered inorganic compound composed of a positively charged basic layer [Mg 1-x Al x (OH)2]x + and a negatively charged intermediate layer [(CO3)x / 2·mH2O]x - Many divalent and trivalent metals have a similar layered structure, and these are represented by the following general formula. [ M 2+1 -xM 3+x (OH)2] x+ [An-x / n·mH2O] x- M 2+ :Mg 2+ ,Zn 2+ divalent metal ions such as M 3+ :Al 3+ ,Fe 3+ trivalent metal ions such as An - :CO3 2- ,Cl - ,NO 3- n-valent anions such as X:0<X≦0.33 Hydrotalcite begins to dehydrate at approximately 180°C, and this crystal water is completely removed at approximately 300°C. Up to this point, synthetic hydrotalcite maintains its crystalline structure, but above approximately 350°C, the crystalline structure begins to break down, releasing water and carbon dioxide. Furthermore, synthetic hydrotalcite begins endothermic decomposition at a temperature between 60°C and 75°C lower than the thermal decomposition temperature of polyvinyl chloride resins (approximately 200°C to 300°C). Therefore, the thermal decomposition of polyvinyl chloride resins can be efficiently suppressed by the endothermic decomposition of hydrotalcite. The heat absorbent may be a combination of at least two of the following: magnesium hydroxide, aluminum hydroxide, kaolin-based minerals, or hydrotalcite.

[0038] The aforementioned heat-dehydrated compound is usually in particulate form. The volume-average particle size of the heat-dehydrated compound is preferably 0.01 μm or more and 20 μm or less, more preferably 0.05 μm or more and 2 μm or less, and even more preferably 0.05 μm or more and 1 μm or less. By setting the volume-average particle size of the heat-dehydrated compound within this range, transparency can be imparted to the pipe fitting A, and the dispersibility of the heat-dehydrated compound can be improved. The volume-average particle size of heat-dehydrated compounds was measured using a laser diffraction scattering particle size distribution analyzer. The BET specific surface area of ​​heat-dehydrated compounds is 1 m². 2 / g or more 40m 2 It is preferable that it be / g, which is 1m 2 / g or more 20m 2 It is preferable that the value is less than or equal to / g. Here, the BET specific surface area is a value obtained using nitrogen adsorption. If the volume-average particle size and BET specific surface area of ​​the heat-dehydrating compound are within the above range, it can fully exert its effect as a heat absorber, and the moldability of the resin composition (A) and the mechanical properties of the pipe fitting A can be sufficiently ensured when manufacturing the pipe fitting A.

[0039] The content of the heat absorbent in the resin composition (A) is preferably 0.01 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of polyvinyl chloride resin, more preferably 0.05 parts by mass or more and 5.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 2.0 parts by mass or less. If the content of the heat absorbent in the resin composition (A) is above the lower limit, deformation of the pipe joint A in the event of a fire can be further suppressed, and if it is below the upper limit, the moldability when manufacturing the pipe joint A can be sufficiently high, and the mechanical properties of the pipe joint A can be improved.

[0040] The resin composition (A) may contain flame retardants other than the heat absorber. Other flame retardants include antimony oxides such as hydrotalcite, antimony dioxide, antimony trioxide, and antimony pentoxide; molybdenum compounds such as molybdenum trioxide, molybdenum disulfide, and ammonium molybdate; brominated compounds such as tetrabromobisphenol A, tetrabromoethane, tetrabromoethane, and tetrabromoethane; phosphorus compounds such as triphenyl phosphate and ammonium polyphosphate; and boric acid compounds such as calcium borate and zinc borate. Among the above other flame retardants, antimony trioxide is preferred because it has a high effect in suppressing the combustion of polyvinyl chloride. Furthermore, the resin composition (A) may contain additives such as lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, heat stabilizers, heat stabilization aids, light stabilizers, ultraviolet absorbers, pigments, plasticizers, and thermoplastic elastomers. Each of the additives described later may be used individually or in combination of two or more.

[0041] "Regarding the shape of pipe joint A" The longitudinal cross-section of pipe joint A in this embodiment is as shown in Figures 2, 4, and 5. The longitudinal section of pipe joint A is defined as the section along the plane containing the pipe axis 2A of the first socket 2, the central axis 1A of the curved pipe section 1, and the pipe axis 3A of the second socket 3, as shown in Figure 4, when the first socket 2 is positioned above and the second socket 3 is positioned below, with the openings 2a of the first socket 2 and 3a of the second socket 3 oriented horizontally, as shown in Figure 4. Figure 2 shows the longitudinal section of pipe joint A, as well as a perspective view of the entire pipe joint A. Figure 5 shows the parting line PL formed when pipe fitting A is manufactured by resin molding, and which is drawn when pipe fitting A is viewed in a longitudinal cross-section. As shown in Figure 5, one end PL1 of the parting line PL is located at the boundary between the lower end of the first socket portion 2 and the curved pipe portion 1, on the curved pipe portion 1 side, and the other end PL2 of the parting line PL is located at the boundary between the upper end of the second socket portion 3 and the curved pipe portion 1, on the curved pipe side. In other words, the parting line PL is formed in the middle of the curved pipe portion 1. As shown in the perspective view of Figure 2, the parting line PL is formed to extend diagonally along the peripheral wall of the curved pipe section 1, connecting one end PL1 and the other end PL2. When a longitudinal section of the pipe joint A is drawn as shown in Figure 5, the parting line PL is drawn as a straight line connecting one end PL1 and the other end PL2. Assuming a cross-section including the parting line PL shown in Figures 4 and 5, the inclination angle of the pipe axis of the first socket section 2 with respect to this cross-section is less than 90° (for example, 45°), and the inclination angle of the pipe axis of the second socket section 3 is also less than 90° (for example, 45°).

[0042] Thus, since the parting line PL is formed to extend diagonally along the circumferential wall of the curved pipe section 1, for example, if the end of the parting line PL on one socket side is taken as the starting point and the end of the parting line PL on the other socket side is taken as the ending point, and viewed from the direction of the central axis of one socket, the starting point of the parting line PL is hidden by the circumferential step section 1g or 1i and cannot be seen from the one socket side. In other words, the starting point of the parting line PL is not located between the central axis of the socket and the circumferential step section when viewed from the direction of the central axis of the socket. To put it another way, the starting point of the parting line PL is not located within the range obtained by projecting the opening circle of the opening 1h or 1f created by the circumferential step section of the socket in the direction of the central axis of the socket, but the ending point of the parting line PL is located within that range. Furthermore, in order to facilitate the removal of the mold core, it is preferable that the starting point of the parting line PL is not located within the range obtained by projecting the opening circle of the opening 2a or 3a created by the socket in the direction of the central axis of the socket, while the ending point of the parting line PL is located within that range. This makes it less likely for the core to interfere with the socket when it is removed.

[0043] The parting line PL is formed in this way because, when manufacturing pipe fitting A, it is produced by resin molding using a mold and a core, and a core 7 with the shape shown in the perspective views of Figures 6 and 7 is used. These cores 7 are placed in the cavity of a mold (not shown) so as to reach the position shown by the dashed line in Figure 4, and then resin molded.

[0044] The core 7 shown in Figure 6 has a disc-shaped base 7A with a thickness approximately equal to the depth of the first socket 2, and an extension 7B that protrudes outward from one end face 7a of the base 7A. The base 7A is disc-shaped with two circular end faces 7a and a circumferential surface 7b sandwiched between the two end faces 7a. The core 7 has a curved, substantially cylindrical (curved shape) extension 7B that protrudes outward from one end face 7a of the base 7A. A flat tip surface 7C is formed at the tip of the extension 7B. In the state shown in Figure 6, with the end face 7a of the core 7 upright, the tip surface 7C of the extension 7B is facing diagonally downward. In the state shown in Figure 6, the length of the outer curved portion 7d on the upper side of the extension 7B is longer than the inner curved portion 7e on the lower side of the extension 7B. The base portion 7A and the extension portion 7B are connected via a connector (not shown), and the base portion 7A and the extension portion 7B are relatively movable and separable. When the core 7 is removed from the pipe joint A, the base portion 7A and the extension portion 7B move individually and separate, and are pulled out from the pipe joint A. The base portion 7A and the extension portion 7B are connected via a connector (not shown), and when the extension portion 7B is rotated, the base portion 7A rotates while being pulled out from the first socket portion 2. The core 7 shown in Figure 7 has the same shape as the core 7 shown in Figure 6, but is positioned so that the orientation of its tip surface 7C is diagonally upward.

[0045] The core 7 in the state shown in Figure 6 is shown to roughly correspond to the orientation of the first socket portion 2 on the right side of the pipe joint A shown in Figures 4 and 5. In Figure 4, the first socket portion 2 is positioned on the right side, but during molding, the base portion 7A in Figure 6 is positioned inside the first socket portion 2 on the right side of Figure 4 as indicated by the dashed line. During molding, the diagonally downward-facing extension portion 7B shown in Figure 6 is positioned inside the curved pipe portion 1 that is continuous with the first socket portion 2 in Figure 4 as indicated by the dashed line. When manufacturing pipe fitting A, cores 7, 7 are placed in the molded cavity of a mold having a shape that mimics the outer shape of pipe fitting A. To form the right-side first socket portion 2 shown in Figure 4, the core 7 shown in Figure 6 is placed in the molding cavity of the mold as indicated by the dashed line on the right side of Figure 4. To form the second socket portion 3 shown on the left side of Figure 4, a core 7 shown in Figure 7 is prepared, with its tip surface 7C facing diagonally upward, and placed in the molding cavity of the mold as shown by the dashed line on the left side of Figure 4. As described above, the two cores 7 shown in Figure 4, positioned in the mold cavity, can be placed with their tip surfaces 7C in close contact with each other. The arrangement of the two cores 7 in the mold cavity is shown by the dashed line in Figure 4. To distinguish between the two cores 7, one core 7 can be called the first core 7, and the other core 7 can be called the second core 7.

[0046] As shown in Figure 4, by positioning the outer curved portion 7d of the right-side core 7, resin injection into the mold cavity forms the pipe wall 1B to the right of the parting line PL shown in Figure 5 in the curved pipe section 1 between the first socket portion 2 and the second socket portion 3. More specifically, the outer curved pipe wall 1E of the pipe wall 1B of the curved pipe section 1 is formed on the outside (upper side) of the outer curved portion 7d of the right-side core 7 in Figure 4. The inner curved pipe wall 1F of the pipe wall 1B of the curved pipe section 1 is formed on the outside (lower side) of the inner curved portion 7e of the right-side core 7 in Figure 4. As shown in Figure 4, by positioning the outer curved portion 7d of the left core 7, resin injection into the mold cavity forms the pipe wall 1C to the left of the parting line PL shown in Figure 5 in the curved pipe section 1 between the first socket portion 2 and the second socket portion 3. More specifically, in the core 7 positioned on the left side of Figure 4, the outer curved pipe section 1G of the pipe wall 1C of the curved pipe section 1 is formed on the outside (lower) side of the outer curved portion 7d. In the core 7 positioned on the left side of Figure 4, the inner curved pipe section 1H of the pipe wall 1B of the curved pipe section 1 is formed on the outside (upper) side of the inner curved portion 7e. Figure 8 shows a partial cross-section of the mold K and a longitudinal cross-section of the pipe joint A formed in the mold cavity S of the mold K. Note that Figure 8 shows the state after the left and right cores 7, 7 have been removed from the mold cavity S, leaving only the molded pipe joint A in the mold cavity S.

[0047] In the pipe joint A shown in Figures 4 and 5, the inner diameter of the first socket portion 2 is formed to be slightly larger than the opening diameter of the opening 1f on the right side of the curved pipe portion 1. Therefore, a circumferential step portion 1g is formed between the opening 1f of the curved pipe portion 1 and the first socket portion 2 outside of it. In the pipe joint A shown in Figures 4 and 5, the inner diameter of the second socket portion 3 is formed to be slightly larger than the opening diameter of the opening 1h on the left side of the curved pipe portion 1. Therefore, a circumferential step portion 1i is formed between the opening 1h of the curved pipe portion 1 and the second socket portion 3 outside it. The curved pipe portion 1 has openings 1f and 1h at both ends.

[0048] In pipe joint A, only a circumferential step 1g is formed between the inner surface of the curved pipe section 1 and the inner surface of the first socket section 2, and only a circumferential step 1i is formed between the inner surface of the curved pipe section 1 and the inner surface of the second socket section 3. Therefore, a smooth inner surface without any protrusions facing inward (towards the flow path) is formed along the entire length of the curved pipe section 1. Since a pipe (not shown) is inserted into the first socket section 2, the end of the pipe abuts against the circumferential step 1g, resulting in the flow path inside the curved pipe section communicating with the pipe connected to the first socket section 2 without any steps. Since another pipe (not shown) is inserted into the second socket section 3, the end of the other pipe abuts against the circumferential step 1i, resulting in the flow path inside the curved pipe section communicating with the pipe connected to the second socket section 3 without any steps.

[0049] The molding cavity S of the mold for forming pipe fitting A has a shape that replicates the outer shape of pipe fitting A inside the mold. Therefore, in order to insert two cores 7 into the molding cavity S in a facing position as shown in Figure 4, it is necessary to insert one core 7 into the molding cavity from the entrance on one end of the molding cavity while rotating it, and then insert the other core 7 into the molding cavity from the entrance on the other end of the molding cavity while rotating it. Therefore, the shape of the extension portion 7B of the core 7 needs to be formed into a special shape as described below.

[0050] Figure 9 shows the core 7 with the base 7A facing the back and the extension 7B facing the front, with the tip surface 7C viewed from the front. The relationship in which the outer curved portion 7d is located above the inner curved portion 7e in the core 7 shown in Figure 6 is the same in the core 7 shown in Figure 9. In the core 7 shown in Figure 9, the width (internal diameter in the horizontal direction) of the tip surface 7C is indicated by (1), and the height (internal diameter in the vertical direction) is indicated by (2). For example, in the case of pipe fitting A connecting pipes with a nominal diameter of 75A, the dimensions of (1) can be 77.20 mm and the dimensions of (2) can be 72.17 mm. Dimension (1) is slightly larger than dimension (2). That is, the relationship (1) > (2) holds. Therefore, the tip surface 7C is formed in an elliptical shape with the inner diameter of (1) as the major axis and the inner diameter of (2) as the minor axis.

[0051] Figure 10 shows a cross-sectional view of the base end of the extension 7B of the core 7. The base end of the extension 7B refers to the position of the extension 7B that is closest to the base 7A. In this cross-section, the width (inner diameter) in the vertical direction is shown by (3), and the width (inner diameter) in the horizontal direction is shown by (5). The width (inner diameter) in the 45° direction, which is midway between the vertical and horizontal directions, is shown by (4). The inner diameter in the 45° direction refers to the inner diameter along the direction obtained by rotating 45° clockwise with respect to the vertical direction, considering the base end cross-section of the extension portion 7B as the clockwise plane. The inner diameter in the horizontal direction refers to the inner diameter along the direction obtained by rotating 90° clockwise with respect to the vertical direction. Furthermore, the inner diameter in the 135° clockwise direction is shown in (6). For example, the inner diameter of (3) can be 77.20 mm, the inner diameter of (4) can be 76.99 mm, the inner diameter of (5) can be 77.17 mm, and the inner diameter of (6) can be 76.99 mm. That is, the relationship between the inner diameters is (3) ≈ (5) > (4) = (6).

[0052] Due to the difference in dimensions between (1) and (2) mentioned above, the cross-section of the extension 7B is elliptical. Also, the dimension of (1) (77.2 mm) at the tip of the extension 7B is approximately equal to the dimension of (5) (77.17 mm) at the base of the extension 7B. In contrast, the dimension of (2) (72.17 mm) at the tip of the extension 7B is smaller than the dimension of (3) (77.2 mm) at the base of the extension 7B, so the vertical dimension of the extension 7B is slightly tapered. In other words, the extension portion 7B is an ellipse in which the inner diameter is larger on the side that is 90° circumferentially shifted from the side defined as the outer curved portion 7d and the inner curved portion 7e, and the extension portion 7B has a tapered shape on the side defined as the outer curved portion 7d and the inner curved portion 7e.

[0053] By making the extension portion 7B of the core 7 the aforementioned elliptical and tapered shape, when removing the rotary core 7 from the mold cavity while rotating it after molding, removal becomes easier. When the core 7 is rotated in the direction indicated by arrow R in Figure 6 to remove it from the mold, the extension portion 7B is made to have the shape described above, which makes removal possible. Specifically, first, the base portion 7A is separated from the extension portion 7B and moved in the direction of the pipe axis 2A to pull out only the base portion 7A from the first socket portion 2. Then, as shown in Figure 4, the right-side core 7 inserted inside the molded pipe joint A is rotated clockwise in the direction of arrow R1, and then pulled outwards from the axis of the first socket portion 2 to be removed. Similarly, the core 7 inserted on the left side of the pipe joint A shown in Figure 4 can be removed by rotating it counterclockwise in the direction of arrow R2, and then pulling it outwards from the axis of the second socket portion 3.

[0054] Furthermore, in order for the two cores 7 to be removable from pipe fitting A, the following conditions must also be satisfied. Figures 11 and 12 show examples where the core cannot be extracted due to the shape of the two cores and pipe fitting. The pipe joint B shown in Figure 11 has a first socket portion 2 and a second socket portion 3 equivalent to those of the pipe joint A of the first embodiment, but the shape of the curved pipe portion 41 is different. In pipe joint B, the radius of curvature of the outer curved pipe wall 41E of the curved pipe portion 41 is formed to be smaller than the radius of curvature of the outer curved pipe wall 1E in the curved pipe portion 1 of the first embodiment. The circumferential surface of the extension portion 42B of the core 42, shown by the two-pointed line, is located inside the outer curved pipe wall 41E. Reference numeral 42C indicates the tip surface of the core 42.

[0055] In the core 42 with the shape shown in Figure 11, the radius of curvature of the circumferential surface of the extension portion 42B is too small, causing the inner circumference of the extension portion 42B to contact the inner surface of the first socket portion 2, making it impossible to remove the core 42. Therefore, unless the radius of curvature of the circumferential surface of the extension portion 42B is made larger than that shown in Figure 11, the core 42 will not be able to be removed from the pipe joint B after molding.

[0056] The pipe joint C shown in Figure 12 has a first socket portion 2 and a second socket portion 3 equivalent to those of the pipe joint A of the first embodiment, but the shape of the curved pipe portion 43 is different. In pipe joint C, the curvature of the outer curved pipe wall 43E of the curved pipe portion 43 is formed to be greater than the curvature of the outer curved pipe wall 1E in the curved pipe portion 1 of the first embodiment. The circumferential surface of the extension portion 44B of the core 44, shown by the two-pointed line, is positioned inside this outer curved pipe wall 43E.

[0057] In the core 44 with the shape shown in Figure 12, the curvature of the circumferential surface of the extension portion 44B is too large, causing the outer circumference of the extension portion 44B to contact the inner surface of the first socket portion 2, making it impossible to remove the core 44. Therefore, unless the radius of curvature of the circumferential surface of the extension portion 44B is made smaller than that shown in Figure 12, the core 44 will not be able to be removed from the pipe joint C after molding.

[0058] The core 7 of the first embodiment has an extension portion 7B having a curvature intermediate between the curvature of the extension portion 42B in the core 42 shown in Figure 11 and the curvature of the extension portion 44B in the core 44 shown in Figure 12. If the extension 7B of the core 7 is as described above, then when removing the right-hand core 7 in the direction of arrow R1 in Figure 4, even if the contour of the outer curved portion 7d is extended in the direction of rotation of the core 7, the contour extension line (dotted line) will be located inside the inner surface of the first socket portion 2 and the opening 2a, so there is no problem when removing the extension 7B of the core 7 from the pipe joint A. In the case of this inside position, for the inner diameter dimensions of the size described above, it is preferable that the contour extension line of the outer curved portion 7d is located about 2 mm or more inside the inner circumferential surface of the first socket portion 2. Furthermore, in the case of core 7, even if the contour of the inner curved portion 7e is extended in the rotational direction of core 7, the extended contour portion is located inside the inner surface of the first socket portion 2, so there is no problem when pulling out the extension portion 7B of core 7 from pipe joint A.

[0059] Figure 13 is a longitudinal cross-sectional view showing the parting line PLO in a conventional pipe fitting D, referred to as an S-socket. Even in the conventional pipe joint D, the basic structure is the same as that of the pipe joint A in the first embodiment, having a first socket portion 2 and a second socket portion 3, and an S-shaped curved pipe portion 8 between the first socket portion 2 and the second socket portion 3. In the conventional technology, as shown by the dashed line in Figure 13, a pipe joint D is formed by molding using two cores 9, each having a disc-shaped base 9A for forming the first socket portion 2 and a fingertip-shaped extension 9B formed protruding from one side of the base 9A. Figure 13 shows an example of the arrangement of the two cores 9 when manufacturing a curved pipe portion 8, as indicated by the dashed line.

[0060] As shown in Figure 13, each fingertip-shaped extension 9B is fingertip-shaped, having a flat portion 9d with a flat surface on the nail side and a belly portion 9e with a curved surface on the ventral side. The core 9, located on the right side, is positioned with the flat portion 9d facing downwards and the belly portion 9e facing upwards. The core 9, located on the left side of Figure 13, is positioned with its flat portion 9d facing upwards and its abdominal portion 9e facing downwards. As shown in Figure 13, the arrangement of cores 9, 9 allows the base 9A of the right core 9 to be used for forming the first socket portion 2, and the base 9A of the left core 9 to be used for forming the second socket portion 3. In addition, the belly portion 9e of the right core 9 and the belly portion 9e of the left core 9 are used together to form the curved pipe portion 8. To achieve the arrangement shown in Figure 13, one core 9 is inserted linearly from the outside of one end of the mold cavity, and the other core is inserted linearly from the outside of the other end of the mold cavity, thereby enabling molding using the mold cavity.

[0061] Figure 14 shows an example of a pipe fitting manufactured using two cores 9 shown in Figure 13 and a mold. The pipe joint D shown in Figure 14 has an S-shaped curved pipe section 8 on one side of the second socket section 3, and a convex step section 8A is formed on the inner surface of this curved pipe section 8, protruding into the flow path of the curved pipe section 8. This step section 8A is an inevitable result when forming the pipe joint D, which has a first socket section 2 and a second socket section 3 with offset axes from each other, by using two cores 9, each having an extension 9B protruding from a base 9A, to form the curved pipe section 8.

[0062] As shown in Figure 13, a parting line PLO is formed along the boundary between the flat portion 9d of the core 9 inserted from the right and the flat portion 9d of the core 9 inserted from the left. Also, as shown in Figure 13, a parting line PLO is generated along the ridge that forms the top of the stepped portion 8A. As long as the core 9 shown in Figure 13 is used, if the inclination of the flat portion 9d is changed, the core 9 will not be able to be removed from the mold cavity, so the parting line PLO is inevitably formed in the position shown in Figure 13. Since the end of this parting line PLO reaches the first receiving portion 2 or the second receiving portion 3, the stepped portion 8A becomes noticeable from the receiving portion side. Furthermore, even if the inclination of the flat portion 9d of the core 9 is changed, the parting line PLO cannot interfere with the circumferential step portion 1g or 1i (if the flat portion 9d interferes with the circumferential step portion, the circumferential step portion will take on a shape as if it were shaved off by the inclination of the flat portion 9d). Therefore, both the start and end points of the parting line PLO are visible without being hidden by the circumferential step portion when viewed from the direction of the central axis of the socket. In other words, both the start and end points of the parting line PLO are located between the central axis of the socket and the circumferential step portion when viewed from the direction of the central axis of the socket. To put it another way, both the start and end points of the parting line PLO are located within the range obtained by projecting the opening circle of the opening 1h or 1f created by the circumferential step portion of the socket in the direction of the central axis of the socket. In a pipe fitting D having a stepped portion 8A, depending on the orientation of the pipe fitting D, there is a risk of drainage pooling in the stepped portion 8A, and water and dust may accumulate in the stepped portion 8A. Also, depending on the orientation of the pipe fitting D, the stepped portion 8A may act as drainage resistance, potentially reducing the drainage speed.

[0063] In contrast, if the pipe joint A has the structure shown in Figures 1 to 5, there is no stepped section on the inside of the curved pipe section 1, so no drainage accumulation occurs inside. Therefore, according to the pipe fitting A of the first embodiment, it is possible to provide a pipe fitting of higher quality than the conventional pipe fitting D.

[0064] In the first embodiment, pipe fitting A has a piping structure in which one pipe is connected to the first socket 2 and another pipe is connected to the second socket 3. The orientation of the opening 2a of the first socket 2 and the orientation of the opening 3a of the second socket 3 are 180° apart. Therefore, the end of the pipe connected to the first socket 2 and the end of the pipe connected to the second socket 3 can be said to be pipes with their ends facing each other. The present invention can also be applied to pipe joints with a structure in which the angle between the pipe axis 2A of the first socket 2 and the pipe axis 3A of the second socket 3, as shown in Figure 4, is 135° or more, such as 45° elbow pipes (where the inclination angle between the pipe axis 2A of the first socket 2 and the pipe axis 3A of the second socket 3 is 135°) and 90° elbow pipes (where the inclination angle between the pipe axis 2A of the first socket 2 and the pipe axis 3A of the second socket 3 is 91.1°).

[0065] The pipe fitting A of the first embodiment may be connected to other drainage members, such as drainage manholes like rainwater manholes or sewage manholes connected to horizontal pipes installed underground, to form a piping structure. The drainage manhole has a cylindrical body that is circular or square when viewed from above, a bottom surface provided at the base of the body, and a receiving port or opening provided on the side of the body. The receiving port or opening of this drainage manhole and the jack or receiving port of the pipe fitting A are connected via adhesive or a rubber ring to form a piping structure. Furthermore, pipe fitting A may include both a first socket portion 2 and a second socket portion 3, and may be connected to the drain manhole via a short pipe to either socket portion.

[0066] "Second Embodiment" Figure 15 shows a second embodiment in which pipe fitting A shown in Figures 1 to 5 is applied to a manifold pipe fitting (drainage manifold pipe fitting) 10. The manifold joint 10 of this embodiment is used for building drainage and is applied to the portion of the through-hole H formed in the floor slab YS. In the embodiment shown in Figure 15, a first vertical pipe P1 of the upper floor is provided above a through hole H formed in the floor slab YS, and a second vertical pipe P2 of the lower floor is provided below it, with a manifold joint 10 provided between them.

[0067] The manifold joint 10 comprises an upper connecting pipe 11 and a lower connecting pipe 12 connected to the upper connecting pipe 11 via an intermediate pipe 15. The upper connecting pipe 11 has a vertical pipe connection portion 13 that can be connected to a first vertical pipe P1, a horizontal pipe connection portion 14 that protrudes from the side of the vertical pipe connection portion 13 and can connect to a single-pipe horizontal pipe P3, and a lower end portion 13A inserted into a through hole H. The manifold joint 10 of this embodiment is composed of an upper connecting pipe 11, a lower connecting pipe 12, and an intermediate pipe 15, which are resin joint components. The intermediate pipe 15 is not required, and the upper connecting pipe 11 and the lower connecting pipe 12 may be directly connected. In this case, either the lower end of the upper connecting pipe 11 or the upper end of the lower connecting pipe 12 serves as the socket, and the other as the receptacle. In the following description, the upper connecting pipe 11 side of the vertical pipe connection 13, along the central axis O of the vertical pipe connection 13, will be appropriately referred to as "upper," and the lower connecting pipe 12 side as "lower."

[0068] The vertical pipe connection section 13 is equipped with a weir plate 13a on its inner surface. The weir plate 13a is installed at an angle of -30° to +30° from the vertical. If the installation angle is tilted more than 20°, the swirling flow of the wastewater swirled by the inclined plate may not be sufficiently weird, potentially causing backflow into the horizontal pipe P3. Furthermore, if the installation angle is tilted more than -30°, the rebound of the received wastewater will be large, potentially disrupting the wastewater flow and causing large pressure fluctuations within the pipe.

[0069] The horizontal pipe connection portion 14 extends cylindrically outward in the radial direction perpendicular to the central axis O from the circumferential wall of the vertical pipe connection portion 13. In this embodiment, two horizontal pipe connection portions 14 are arranged in the circumferential direction of the vertical pipe connection portion 13. Note that the number and direction of extension of the horizontal pipe connections 14 are not limited to this configuration and can be changed as desired. As shown in Figure 1, a horizontal pipe (single pipe) P3 is connected to the tip of each horizontal pipe connection 14.

[0070] The upper connecting pipe 11 is made of a polyvinyl chloride resin composition containing, for example, 0.1 to 1.0 parts by weight of non-expandable graphite per 100 parts by weight of polyvinyl chloride resin. The upper connecting pipe 11 is obtained, for example, by injection filling the polyvinyl chloride resin composition into the cavity of a molding machine. An intermediate pipe 15 is connected to the lower end of the upper connecting pipe 11. The outer diameter of the intermediate pipe 15 is smaller than the outer diameter of the vertical pipe connection portion 13 of the upper connecting pipe 11. The upper part of the peripheral wall of the intermediate pipe 15 is fitted inside the lower end portion 13A of the vertical pipe connection portion 13. Alternatively, the intermediate pipe 15 may have a socket with an outer diameter larger than the outer diameter of the vertical pipe connection portion 13 of the upper connecting pipe 11.

[0071] The intermediate pipe 15 is made of a resin composition containing, for example, a polyvinyl chloride resin and thermally expandable graphite, which is a thermally expandable refractory material. That is, the intermediate pipe 15 is made by molding a resin composition containing a thermally expandable refractory material. The intermediate pipe 15 is made, for example, by extrusion molding of the resin composition. The intermediate pipe 15 may be a single-layer structure made entirely of a resin composition containing a thermally expandable refractory material, or it may be a multi-layer structure consisting of multiple layers. In the case of a multi-layer structure, it is sufficient that any one of the layers is formed from a resin composition containing a thermally expandable refractory material. For example, if the intermediate pipe 15 has a three-layer structure consisting of a surface layer, an intermediate layer, and an inner layer, the intermediate layer may be made from a resin composition containing a thermally expandable refractory material, and the surface layer, intermediate layer, and inner layer may contain a heat absorbent in their resin compositions.

[0072] The lower connecting pipe 12 consists of a pipe body that is narrower in diameter at the bottom than at the top. The lower connecting pipe 12 includes a connecting pipe section 16 located at its upper end and connected to the lower end of the intermediate pipe 15, a tapering inclined pipe section 17 connected below the connecting pipe section 16, and a lower pipe section 18 connected to the lower end of the inclined pipe section 17, to which the second vertical pipe P2 is connected. The connecting pipe section 16, the inclined pipe section 17, and the lower pipe section 18 are integrally formed, for example, by injection molding of a synthetic resin material.

[0073] The inner diameter of the connecting pipe section 16 is larger than the outer diameter of the intermediate pipe 15. The lower part of the peripheral wall of the intermediate pipe 15 is fitted inside the connecting pipe section 16. The outer diameter at the upper end of the inclined pipe section 17 is smaller than the outer diameter of the connecting pipe section 16. Therefore, a circumferential step section 16a is formed at the boundary between the lower end of the connecting pipe section 16 and the upper end of the inclined pipe section 17. The outer diameter at the lower end of the inclined pipe section 17 is smaller than the outer diameter at the upper end of the inclined pipe section 17. The outer diameter of the connecting pipe section 16 may be smaller than the inner diameter of the intermediate pipe.

[0074] The outer diameter of the lower pipe section 18 is smaller than the outer diameter of the connecting pipe section 16, and larger than the outer diameter of the lower end of the inclined pipe section 17. The size of the lower pipe section 18 in the direction of the central axis O is smaller than the size of the connecting pipe section 16 in the direction of the central axis O. The second vertical pipe P2 of the lower floor is fitted inside the lower pipe section 18 from below, thereby connecting the second vertical pipe P2 to the lower connecting pipe 12.

[0075] The upper end of the upper connecting pipe 11 to which the first vertical pipe P1 is connected is provided with a vertical bush 21, a vertical packing 22, and a vertical ring 23. The vertical bush 21 comprises a fitting portion 21a, a swivel vane 21b, and a swivel vane support leg portion 21c. The fitting portion 21a is cylindrical in shape, having a smaller diameter than the upper end of the vertical bush 21, and fits into the vertical pipe connection portion 13 of the upper connecting pipe 11.

[0076] The swivel blade 21b is supported by the swivel blade support leg 21c such that the projected area of ​​the swivel blade 21b, viewed in the direction of the pipe axis, is 5% to 30% of the internal cross-sectional area of ​​the first vertical pipe P1, and the inclination angle is 20° to 50°. The swivel blade support leg 21c extends almost the same width as the horizontal width of the swivel blade 21b and extends almost from the lower end of the fitting portion 21a, with its lower edge inclined to follow the inclination of the swivel blade 21b. The swivel blade support surface of the swivel blade support leg 21c is formed in a circular arc shape in cross-section, and supports the swivel blade 21b slightly above its lower edge. Note that the swivel vane 21b is applied when high drainage performance is required depending on the size of the building and the number of drainage fixtures; therefore, it may be omitted in buildings where high drainage performance is not required.

[0077] The vertical packing 22 is made of a rubber material commonly used in drainage equipment, such as ethylene-propylene-diene rubber (EPDM). The vertical packing 22 has a lip portion 22a at its upper end that tightly seals to the outer surface of the first vertical pipe P1, and its upper end surface is fitted into the vertical bush 21 so as to substantially coincide with the upper end surface of the vertical bush 21. Furthermore, as shown in Figure 16, the lip portion 22a is designed to gradually decrease in diameter towards the lower end when the first vertical pipe P1 is not inserted. The upper end of the lip portion 22a is approximately the same diameter as or slightly larger than the outer diameter of the first vertical pipe P1, while the lower end is smaller in diameter than the outer diameter of the first vertical pipe P1. A stepped portion 22b is formed at the lower end of the lip portion 22a, projecting radially inward. The end of the first vertical pipe P1 abuts against this stepped portion 22b, absorbing the thermal expansion and contraction of the first vertical pipe P1.

[0078] The vertical ring 23 is fitted onto the upper end of the vertical bush 21, and a flange portion 23a provided at one end prevents the vertical packing 22 from detaching from the vertical bush 21. The vertical bushings 21 to the vertical ring 23 can be assembled and integrated beforehand, and then the fitting portion 21a of the vertical bushing 21 can be fitted onto the vertical pipe connection portion 13 of the upper connecting pipe 11 and bonded together. The tip of the horizontal pipe connection section 14, which connects the horizontal pipe P3, is provided with a horizontal bush 31, a horizontal packing 32, and a horizontal ring 33. One end of the horizontal bush 31 is fitted and bonded to the horizontal pipe connection portion 14 of the upper connecting pipe 11, while the other end is enlarged in diameter.

[0079] The horizontal packing 32 is made of a rubber material commonly used in drainage equipment, such as ethylene-propylene-diene rubber (EPDM). The horizontal packing 32 is fitted to the enlarged other end of the horizontal bush 31 and tightly seals to the outer surface of the horizontal pipe P3 in a watertight manner. The horizontal ring 33 is fitted onto the enlarged diameter portion of the horizontal bush 31, and a flange portion 33a provided at one end prevents the horizontal packing 32 from detaching from the vertical ring 23. Furthermore, the vertical bush 21, vertical ring 23, and horizontal bush 31, horizontal ring 33 are all obtained by injection molding a polyvinyl chloride resin composition containing 0.1 to 1.0 parts by weight of non-expandable graphite per 100 parts by weight of polyvinyl chloride resin.

[0080] The through-holes H in the floor slab YS are filled with a filler material (sound insulation material) M such as mortar or rock wool, and the upper end of the lower connecting pipe 12, the intermediate pipe 15, and the lower end of the upper connecting pipe 11 are embedded in the filler material M. The upper end of the inclined pipe section 17 and the connecting pipe section 16 of the lower connecting pipe 12 are embedded in the filler material M. The portion of the upper connecting pipe 11 below the lower end of the horizontal pipe connection section 14 (lower end 14A) is embedded in the filler material M. It is preferable to use mortar with excellent residue retention properties as the filler material M. Then, the end of the horizontal pipe P3 is inserted into the horizontal bush 31 via the horizontal ring 33 and the horizontal packing 32, thereby connecting the horizontal pipe (single pipe) P3.

[0081] As shown in Figures 15 and 16, two pipe fittings A are connected to the manifold pipe fitting 10, as shown in Figure 17. As shown in Figure 15, the right-hand horizontal pipe P3 is fitted into the first socket 2 of one pipe fitting A, connecting one pipe fitting A. Similarly, the left-hand horizontal pipe P3 shown in Figure 15 is fitted into the first socket 2 of the other pipe fitting A, connecting the pipe fitting A. The second socket 3 of each pipe fitting A is connected to other pipes P4 and P5.

[0082] As shown in Figure 17, by connecting pipe fitting A to opposing positions on the manifold pipe fitting 10, pipes P4 and P5 can be connected at a position slightly offset horizontally from the horizontal pipe connection section 14. Therefore, even if the axial position of the horizontal pipe connection section 14 of the manifold pipe fitting 10 and the axial positions of pipes P4 and P5 are slightly misaligned, the pipes can be connected while eliminating the misalignment. Figure 17 shows the case where pipes P4 and P5, which are horizontally axially misaligned with respect to the manifold joint 10, are connected. However, even if pipes P4 and P5 and the horizontal pipe connection part 14 are slightly misaligned in the vertical or diagonal direction, the pipe joint A can be used for misalignment adjustment by adjusting the height positions of the first socket part 2 and the second socket part 3. In this case, conventional pipe fittings D, as shown in Figure 13, have a convex step portion 8A that protrudes into the flow path of the curved pipe section 8. As a result, sewage and waste accumulate in the step portion 8A within the curved pipe section 8, obstructing drainage. However, pipe fitting A does not have a step portion 8A, so sewage and waste do not accumulate within the curved pipe section 8.

[0083] Furthermore, not only to adjust for misalignment, but also because if piping P4 is equipped with facilities that forcefully drain wastewater, such as toilets, there is a risk of wastewater from piping P4 flowing back into piping P5 on the opposite side of piping P4. Therefore, it is sometimes prohibited to install piping on the side of piping P5 that is opposite to piping P4. Even in such cases, in this embodiment, by connecting pipes P4 and P5 via pipe joint A, the force of the drainage is reduced in the S-shaped flow path of pipe joint A, preventing backflow into the opposing pipe. In such cases, it is preferable that the manifold joint 10 used is pre-connected to the horizontal pipe connection part 14 with an adhesive or the like at the factory where the manifold joint 10 is manufactured.

[0084] "Third Embodiment" Figure 18 shows a third embodiment in which pipe fitting A shown in Figures 1 to 5 is applied to the connection of the toilet drain pipe. In this embodiment, the drain pipe 52 of the toilet 51 installed on the floor slab 50 is installed horizontally along the floor slab, and the end of this drain pipe 52 is fitted into the first socket 2 of the pipe joint A. A horizontal pipe 55A (single pipe) provided in a manifold pipe joint 55 that connects the drain pipes 53 and 54 of the upper and lower floors of the building is fitted into the second socket 3 of the pipe joint A.

[0085] In Figure 18, drain pipes 53 and 54 and a manifold pipe fitting 55 are installed in the piping space R on the back side of the partition wall 56 located behind the toilet bowl 51. When the horizontal position of the horizontal pipe 55A of the manifold pipe fitting 55 is slightly lower than the horizontal position of the drain pipe 52 of the toilet bowl 51, the pipe fitting A is applied to absorb the misalignment of the piping and connect the pipes. As shown in Figure 18, pipe fitting A can connect pipes while absorbing vertical misalignment even when the pipe positions are slightly misaligned in the vertical direction.

[0086] "Fourth Embodiment" Figure 19 shows a fourth embodiment in which pipe joint A, shown in Figures 1 to 5, is applied to a rain gutter. The rain gutter 60 shown in Figure 19 is installed along the roof 63 which is supported by the exterior wall 62 of the building, and a pipe joint A is connected to the downpipe 64 which is connected to the eaves gutter 61 installed at the eaves of the roof 63. The eaves gutter 61 is horizontally suspended and supported at the eaves of the roof 63 by a support 65. The gutter 61 has a concave cross-section, with a base plate 61A and side plates 61B erected on both sides of the base plate 61A in the width direction. The gutter 61 is installed along the roof 63 on the eaves side. The support 65 is assembled in a rectangular frame shape, and its upper end 65A is fixed to the roof 63 by a fastener 66. Multiple support 65s are provided along the eaves of the roof 63 at predetermined intervals, and the gutter 61 is supported by multiple support 65s.

[0087] An upper drain member 67 is positioned on the bottom plate 61A of the gutter 61, and a lower drain member 68 is positioned below the bottom plate 61A, with the upper drain member 67 and the lower drain member 68 connected. The lower drain member 68 is provided so as to penetrate the bottom plate 61A of the gutter 61, and its internal flow path is in communication with the internal flow path of the upper drain member 67.

[0088] An outer cylindrical portion 70 is formed at the bottom of the lower drain member 68 so as to protrude downward, and this outer cylindrical portion 70 is connected to the first socket portion 2 of the pipe joint A. A downpipe 64, supported along the outer wall 62, is connected to the second socket portion 3 of the pipe joint A. In the structure of the fourth embodiment, the second receiving portion 3 is installed closer to the outer wall 62 than the first receiving portion 2, and the downpipe 64 is connected to the second receiving portion 3. Furthermore, the outer cylinder portion 70 and the first receiving portion 2 are not limited to being directly connected; they may also be connected via a downpipe 64 of a predetermined length.

[0089] In the fourth embodiment, a downpipe 64 is installed along the outer wall 62, and the axis of the upper drain member 67 and the axis of the lower drain member 68 are located slightly away from the outer wall 62 than the position where the downpipe 64 is installed. As shown in Figure 19, even if the horizontal position of the axis of the downpipe 64 is misaligned with respect to the axis of the upper drain member 67 and the axis of the lower drain member 68, the pipe joint A can absorb this misalignment, making it possible to connect to the downpipe 64. The downpipe 64 shown in Figure 19 is fixed to the exterior wall 62 by fittings (not shown), but even if the distance from the exterior wall 62 to the center of the eaves gutter 61 and the distance from the exterior wall 62 to the downpipe 64 are slightly different, connection using pipe joint A is possible.

[0090] In this embodiment, the upper drain member 67 is preferably a high-drainage type upper drain member that has, for example, a top plate 67A and a plurality of support walls 67B that support the top plate 67A, with a drain opening 67C formed between the plurality of support walls 67B. With this upper drain member 67, even in the event of heavy rainfall, when a large amount of rainwater flows into the downpipe 64 via the gutter 61, the proportion of air drawn into the downpipe 64 is small. Therefore, a full flow is created inside the downpipe 64 using the siphon effect of the upper drain member 67. In the downpipe 64, which has become a full flow due to the upper drain member 67, the siphon effect occurs, and the flow velocity of the rainwater sucked in from the upper drain member 67 increases due to the induced siphon effect, enabling high-speed drainage. In this case, conventional pipe fittings D, as shown in Figure 13, have a convex step portion 8A that protrudes into the flow path of the curved pipe section 8. This reduces the flow velocity in the curved pipe section 8, hindering the occurrence of the siphon effect and the increase in flow velocity due to the induced siphon effect. However, pipe fitting A does not have a step portion 8A and therefore does not hinder the siphon effect. [Explanation of Symbols]

[0091] A...Pipe joint, 1...Bent pipe section, 1A...Central axis, 1f, 1h...Opening, 2...First socket section (first connection section), 2A...Pipe axis, 2a...Opening, 3...Second socket section (second connection section), 3A...Pipe axis, 3a...Opening, 7...Core (First core: Second core), 7A...Base, 7B...Extension section, 10...Collector pipe joint, 11...Upper connecting pipe, 12...Lower connecting pipe, 13...Vertical pipe connection section ,14…Horizontal pipe connection, 15…Intermediate pipe, P3…Horizontal pipe (single pipe), 51…Toilet bowl, 52…Drain pipe, 55…Collection pipe joint, 55A…Horizontal pipe (single pipe), 60…Rain gutter, 61…Eaves gutter, 62…Exterior wall, 63…Roof, 64…Downpipe, 67…Upper drain member, 68…Lower drain member, K…Mold, S…Molding cavity, PL…Parting line, PL1…One end, PL2…Other end

Claims

1. A curved pipe section having a flow path inside and openings at both ends, The curved pipe section has an annular first connecting portion surrounding the opening at one end and an annular second connecting portion surrounding the opening at the other end. A pipe fitting made of a single piece of resin, having a parting line from the molding process in the middle of the curved pipe section.

2. The cross-section of the curved pipe portion, including the parting line, is elliptical. The pipe fitting according to claim 1.

3. At least one of the first and second connecting portions is a connecting portion for connecting pipes with opposing ends. The pipe fitting according to claim 1.

4. The angle between the pipe axis of the first connection and the pipe axis of the second connection is 135° or more. The pipe fitting according to claim 1.

5. The inclination angle of the first connection portion and the inclination angle of the second connection portion of the surface including the parting line with respect to the pipe axis are both less than 90°. The pipe fitting according to claim 1.

6. When the first connecting portion is positioned above and the second connecting portion is positioned below, with the openings of the first and second connecting portions facing sideways, and the cross-section along the plane containing the pipe axis of the first connecting portion, the central axis of the curved pipe portion, and the pipe axis of the second connecting portion is defined as the vertical cross-section of the first connecting portion, the curved pipe portion, and the second connecting portion, One end of the parting line is located at the boundary between the lower end of the first connection and the curved pipe section, on the side of the curved pipe section, and the other end of the parting line is located at the boundary between the upper end of the second connection and the curved pipe section, on the side of the curved pipe section. The pipe fitting according to claim 1.

7. A pipe fitting according to any one of claims 1 to 6, The pipe fittings are connected to a pipe or drainage member, Piping structure.

8. A curved pipe section having a flow path inside and openings at both ends, A pipe joint having an annular first connecting portion surrounding the opening at one end of the curved pipe section and an annular second connecting portion surrounding the opening at the other end of the curved pipe section, and being a resin integral molded product, with a parting line from the molding process in the middle of the curved pipe section, A single pipe is connected to a part of either the upper connecting pipe, the intermediate pipe connected to this upper connecting pipe, or the lower connecting pipe connected to this intermediate pipe. Manifold pipe joint.

9. A rain gutter comprising a eaves gutter, an upper drain member installed on the bottom plate of the eaves gutter, a lower drain member connected to the upper drain member, and a downpipe connected to the lower drain member, With respect to the aforementioned downpipe, A curved pipe section having a flow path inside and openings at both ends, The pipe joint, which is a resin integral molded product and has an annular first connecting portion surrounding the opening at one end of the curved pipe section and an annular second connecting portion surrounding the opening at the other end of the curved pipe section, is connected between the lower drain member and the downpipe, and has a parting line from the molding process in the middle of the curved pipe section. Rain gutter.

10. A resin integral molded product having a curved pipe section with a flow path inside and openings at both ends, an annular first connecting section surrounding the opening at one end of the curved pipe section, and an annular second connecting section surrounding the opening at the other end of the curved pipe section, wherein the pipe joint has a parting line in the middle of the curved pipe section, when manufactured by resin molding using a mold with a molding cavity and a core inserted into the molding cavity, A base portion for forming the first connecting portion within the molding cavity, and a first core having a curved extension portion for forming the portion of the curved pipe section that continues from the first connecting portion within the molding cavity, A second core is used, which has a base for forming the second connecting portion within the molding cavity and a curved extension for forming the portion of the curved pipe section that continues from the second connecting portion within the molding cavity. The first core and the second core are inserted into the molded cavity while rotating them in a direction along the curved shape of the extension, and the tip of the extension of the first core and the tip of the extension of the second core are brought together inside the molded cavity. The resin is injected into the molded cavity to form the shape. A method for manufacturing pipe fittings.

11. When the first connecting portion is positioned above and the second connecting portion is positioned below, with the openings of the first and second connecting portions facing sideways, and the cross-section along the plane containing the pipe axis of the first connecting portion, the central axis of the curved pipe portion, and the pipe axis of the second connecting portion is defined as the vertical cross-section of the first connecting portion, the curved pipe portion, and the second connecting portion, One end of the parting line is located at the boundary between the lower end of the first connection and the curved pipe section, on the side of the curved pipe section, and the other end of the parting line is located at the boundary between the upper end of the second connection and the curved pipe section, on the side of the curved pipe section. A method for manufacturing a pipe joint according to claim 10.

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