Joints and methods for manufacturing joints

Abstract

To reduce the need for molds in joints and their manufacturing methods. [Solution] The joint 1 comprises at least two receiving portions 2 and a main body portion 3 connecting the receiving portions 2, wherein at least the main body portion 3 has an inner layer portion 31 made of resin and an outer layer portion 32 made of fiber-reinforced resin.

Description

Technical Field

[0001] The present invention relates to a joint and a method for manufacturing the joint.

Background Art

[0002] In the laying of sewer pipes, agricultural water pipes, etc., joints are used as members for connecting pipes. The material of the joint is appropriately selected according to the environment of the installation location, the fluid flowing through it, etc. One typical material is fiber-reinforced resin. Since fiber-reinforced resin belongs to a category of materials with high strength as a resin material, it is used for joints that require particularly high strength.

[0003] Examples of joints using fiber-reinforced resin as the main material can be found in, for example, Japanese Patent Application Laid-Open No. 2010-195022 (Patent Document 1) and International Publication No. 2024 / 089982 (Patent Document 2). Among these, Patent Document 1 discloses a method for manufacturing a joint including winding a reinforcing fiber bundle impregnated with a polymerizable resin composition containing a photoinitiator around a mold. The method using a mold as in Patent Document 1 is one of the typical methods for manufacturing joints made of fiber-reinforced resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The method of manufacturing fittings using molds, as described in Patent Document 1, is sometimes applied when other molding methods such as injection molding are difficult to apply, and is often applied to relatively large-diameter fittings, for example. Therefore, businesses that manufacture fittings using molds need to possess large molds, and the manufacturing costs and storage space required for this have been obstacles to expanding the range of fittings. In addition, the need to handle large molds can lead to significant equipment and human resource constraints in the manufacturing of fittings.

[0006] Therefore, it is desirable to reduce the need for molds in joints and their manufacturing methods. [Means for solving the problem]

[0007] The joint according to the present invention comprises at least two socket portions and a main body portion connecting the socket portions, wherein at least the main body portion has an inner layer portion made of resin and an outer layer portion made of fiber-reinforced resin.

[0008] A method for manufacturing a joint according to the present invention is a method for manufacturing a joint comprising at least two socket portions and a main body portion connecting the socket portions, characterized in that it includes an inner layer forming step of forming an inner layer portion made of resin at least as part of the main body portion, and an outer layer forming step of curing resin on the outside of the inner layer portion to form an outer layer portion.

[0009] With these configurations, since a mold is not required for at least the formation of the main body, it is possible to manufacture a resin-containing joint and its components without using a mold, or by reducing the dimensions of the mold used. In other words, the need for a mold is reduced.

[0010] Preferred embodiments of the present invention will be described below. However, the scope of the present invention is not limited by the examples of preferred embodiments described below.

[0011] In one embodiment, the joint according to the present invention is preferably formed by adding resin to the inner layer portion.

[0012] This configuration allows for greater flexibility in the shape of the inner layer, making it easier to create joints of the desired shape.

[0013] In the joint according to the present invention, it is preferable that the inner layer portion includes a core portion formed by adding resin with the socket portion as the base end, and the outer layer portion is formed by wrapping an inorganic fiber sheet impregnated with a thermosetting resin around the core portion and then curing the thermosetting resin.

[0014] This configuration allows for greater flexibility in the shape of the inner layer, making it easier to create joints of the desired shape. Furthermore, it tends to increase the strength of the outer layer.

[0015] In one embodiment of the joint according to the present invention, it is preferable that at least one of the socket portions is made of fiber-reinforced resin.

[0016] This configuration tends to increase the strength and dimensional accuracy of the socket.

[0017] In one embodiment, the joint according to the present invention preferably has an inner layer portion that extends across the main body portion and at least one of the socket portions.

[0018] With this configuration, the inner layer portion, which spans both the main body and the receiving portion, can be used as a core to form the outer layer portion. This reduces the need for molds not only for the main body but also for the receiving portion.

[0019] In one embodiment, the joint according to the present invention preferably has a sealing material receiving groove on the inner surface of the receiving portion for accommodating a sealing material.

[0020] This configuration makes it easier to ensure a secure connection between the fittings and the piping.

[0021] In one embodiment, the joint according to the present invention is preferably such that, for at least one pair of socket portions, the angle formed by the two directions in which the two socket portions extend is greater than 90° and less than 180°.

[0022] According to this configuration, it is easy to add joints with relatively low demand to the inventory.

[0023] The method for manufacturing a joint according to the present invention further includes, as one aspect, a receiving portion forming step of curing a thermosetting resin to form at least one of the receiving portions, and it is preferable that the inner layer forming step includes forming the inner layer portion extending from the receiving portion formed in the receiving portion forming step as a base end.

[0024] According to this configuration, since the degree of freedom in the shape of the inner layer portion is high, it is easy to realize a joint having a desired shape.

[0025] The method for manufacturing a joint according to the present invention further includes, as one aspect, a resin addition molding with the receiving portion as a base end to form a core portion of the main body portion, and it is preferable that the inner layer forming step includes forming the inner layer portion.

[0026] According to this configuration, since the degree of freedom in the shape of the inner layer portion is high, it is easy to realize a joint having a desired shape.

[0027] The method for manufacturing a joint according to the present invention further includes, as one aspect, a resin impregnated inorganic fiber sheet containing the thermosetting resin is wound around the core portion and then the thermosetting resin is cured to form the outer layer portion, and it is preferable that the outer layer forming step includes forming the outer layer portion.

[0028] According to this configuration, the strength and dimensional accuracy of the receiving portion are likely to be high.

[0029] The method for manufacturing a joint according to the present invention further includes, as one aspect, a resin addition molding with the receiving portion as a base end to form a core portion of the main body portion, and it is preferable that the inner layer forming step includes forming the inner layer portion extending over the main body portion and at least one of the receiving portions.

[0030] According to this configuration, since the inner layer portion extending over the main body portion and the receiving portion can be used as a core to form the outer layer portion, the necessity of a mold can be reduced not only for the main body portion but also for the receiving portion.

[0031] In one embodiment of the method for manufacturing a joint according to the present invention, it is preferable that the inner layer forming step includes shrinking the resin shrink tube to form the inner layer portion.

[0032] This configuration makes it easy to form the inner layer.

[0033] Further features and advantages of the present invention will become clearer through the following description of exemplary and non-limiting embodiments, with reference to the drawings. [Brief explanation of the drawing]

[0034] [Figure 1] This is a cross-sectional view of the joint according to the first embodiment. [Figure 2] This is a cross-sectional view showing the fitting in use according to the first embodiment. [Figure 3] This is a cross-sectional view of the first intermediate product obtained when manufacturing a joint according to the first embodiment. [Figure 4] This is a cross-sectional view of a second intermediate product obtained when manufacturing a joint according to the first embodiment. [Figure 5] This is a cross-sectional view of the joint according to the second embodiment. [Figure 6] This is a cross-sectional view of the joint according to the third embodiment. [Figure 7] This is a cross-sectional view showing the usage state of the joint according to the third embodiment. [Modes for carrying out the invention]

[0035] Embodiments of the joint and method for manufacturing the joint according to the present invention will be described with reference to the drawings. Three exemplary embodiments of the present invention will be shown below, but before describing them, matters common to the three embodiments will be explained.

[0036] [Common matters] Each embodiment of the joint comprises at least two socket portions and a main body portion connecting the socket portions. At least the main body portion has an inner layer portion made of thermoplastic resin and an outer layer portion made of fiber-reinforced resin.

[0037] A fitting can connect the same number of pipes as the number of sockets. For example, a fitting with two sockets can connect two pipes, which allows for the extension of the flow path formed by the pipes. Here, the direction of extension of the flow path is determined by the angle θ between the two directions in which the two sockets extend. In other words, the direction in which the sockets extend can be rephrased as the direction in which the pipe extends when it is connected to the socket. For example, if the angle θ between the two directions in which the two sockets extend is 180°, the pipes are connected in a straight line by the fitting, and the flow path is extended in a straight line. Also, for example, if the angle θ between the two directions in which the two sockets extend is approximately 90°, the pipes are connected at approximately a right angle by the fitting, and the flow path is extended by bending at approximately a right angle. In the drawings of each embodiment below, the angle θ is shown as necessary.

[0038] As an example, a fitting with three sockets can connect three pipes, allowing for the extension and branching of the flow path formed by the pipes. This type of fitting is used when branching a fluid from one fluid source to two destinations, or when merging fluids from two different fluid sources. The angle formed by the directions in which the sockets extend determines the direction of extension of the flow path before and after branching, just as in the case with two sockets. The function of fittings with four or more sockets can also be understood in a similar manner.

[0039] In the following embodiments, for the sake of simplicity, the explanation will be given using the example of a case where there are two sockets. Furthermore, specific examples will be given to illustrate the configuration of the extension direction of the sockets. However, none of the embodiments preclude other configurations regarding the number and extension direction of the sockets.

[0040] The resin constituting the inner layer of the main body is not particularly limited and is appropriately selected according to the required performance of the joint and the applicable manufacturing method. Examples of resins include thermoplastic resins and thermosetting resins, but are not limited to these. Examples of thermoplastic resins include high-density polyethylene (HDPE), low-density polyethylene (LDPE), propylene polymers (propylene homopolymer (PP), etc.), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polystyrene (PS), polyvinyl acetate (PVAc), acrylonitrile butadiene styrene resin (ABS resin), styrene acrylonitrile copolymer (AS resin), acrylic resin (PMMA, etc.), polyamide (PA), polyacetal (POM), polycarbonate (PC), and modified polyphenylene ether (m Examples of such materials include, but are not limited to, PPE (modified PPE, PPO), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), syndiotactic polystyrene (SPS), cyclic polyolefin (COP), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone (PSF), polyethersulfone (PES), amorphous polyarylate (PAR), polyetheretherketone (PEEK), thermoplastic polyimide (PI), and polyamideimide (PAI). In particular, from the viewpoint of further suppressing warping of the molded product, the thermoplastic resin preferably contains one or more selected from the group consisting of high-density polyethylene (HDPE), propylene polymers, polyamide (PA), polybutylene terephthalate (PBT), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), and polyacetal (POM), and more preferably contains propylene polymers. Examples of thermosetting resins include, but are not limited to, polyurethane (PU), epoxy resin (EP), phenolic resin (PF), melamine resin (MF), alkyd resin, and silicone resin.

[0041] The fiber-reinforced resin constituting the outer layer of the main body is not particularly limited and is appropriately selected according to the required performance of the joint and the applicable manufacturing method. In other words, both the matrix resin and the fiber material constituting the fiber-reinforced resin are arbitrary. Examples of matrix resins include thermoplastic resins and thermosetting resins, but are not limited to these. Examples of thermoplastic resins include high-density polyethylene (HDPE), low-density polyethylene (LDPE), propylene polymers (propylene homopolymer (PP), etc.), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polystyrene (PS), polyvinyl acetate (PVAc), acrylonitrile butadiene styrene resin (ABS resin), styrene acrylonitrile copolymer (AS resin), acrylic resin (PMMA, etc.), polyamide (PA), polyacetal (POM), polycarbonate (PC), and modified polyphenylene ether (m Examples of such materials include, but are not limited to, PPE (modified PPE, PPO), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), syndiotactic polystyrene (SPS), cyclic polyolefin (COP), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone (PSF), polyethersulfone (PES), amorphous polyarylate (PAR), polyetheretherketone (PEEK), thermoplastic polyimide (PI), and polyamideimide (PAI). In particular, from the viewpoint of further suppressing warping of the molded product, the thermoplastic resin preferably contains one or more selected from the group consisting of high-density polyethylene (HDPE), propylene polymers, polyamide (PA), polybutylene terephthalate (PBT), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), and polyacetal (POM), and more preferably contains propylene polymers. Examples of thermosetting resins include, but are not limited to, polyurethane (PU), epoxy resin (EP), phenolic resin (PF), melamine resin (MF), alkyd resin, and silicone resin. Examples of fibrous materials include, but are not limited to, glass fiber, carbon fiber, and aramid fiber. In addition, the combination of matrix resin and fibrous material is arbitrary.

[0042] There is no prejudice to the incorporation of various additives into both the resin constituting the inner layer and the fiber-reinforced resin constituting the outer layer. Examples of such additives include, but are not limited to, heat stabilizers, antistatic agents, weather stabilizers, light stabilizers, UV absorbers, anti-aging agents, antioxidants, neutralizing agents, fatty acid metal salts, softeners, dispersants, colorants, lubricants, pigments, dyes, fillers, whitening agents, antistatic agents, solvents, wetting agents, antimicrobial agents, chelating agents, flow aids, reinforcing agents, energy absorption enhancers, energy absorption inhibitors, laser absorbers, fusion agents, and finish enhancers.

[0043] The material constituting the socket portion is not particularly limited and may be, for example, a thermosetting resin or a thermoplastic resin. If the material constituting the socket portion is a resin, there is no prejudice to incorporating various additives into the resin. In this case, the additives include fibrous materials. Therefore, the socket portion may be made of fiber-reinforced resin. If the socket portion is made of fiber-reinforced resin, the fiber-reinforced resin constituting the socket portion and the thermosetting resin constituting the outer layer portion of the main body may be the same or different from each other. Furthermore, multiple socket portions may be made of the same material or different from each other.

[0044] [First Embodiment] (Connection configuration) The joint 1A according to the first embodiment comprises two socket portions 2 and a main body portion 3 connecting the two socket portions 2 (Figure 1). The main body portion 3 has a core portion 31 as an inner layer portion and an outer layer portion 32 formed on the outside of the core portion. In the joint 1A, the angle θ formed by the two directions in which the two socket portions 2 extend is 135°. When the joint 1A is in use, an annular sealing material S that seals the space between the inner surface of the joint 1A (socket portion 2) and the pipe P, and a detachment prevention material R that prevents the pipe P from falling out of the joint 1A are provided, and the socket portion 2 has a sealing material receiving groove 21 for receiving the sealing material S and a detachment prevention material receiving groove 22 for receiving the detachment prevention material R on its inner surface (Figure 2).

[0045] The receiving portion 2 is preferably made of fiber-reinforced resin, and more preferably made of fiber-reinforced resin containing thermosetting resin. When the receiving portion 2 is made of fiber-reinforced resin, the strength and dimensional accuracy of the receiving portion 2 tend to be higher.

[0046] The core portion 31 is formed by additive molding of resin using a pre-manufactured socket portion 2 as the base end. The resin constituting the core portion 31 is not limited to those that can be additive molded. Therefore, as the resin constituting the core portion 31, a resin suitable for additive molding can be used by selecting the melting point, fluidity, additives, etc., from among the resins exemplified in the common items section above. Characteristics of such a resin include, for example, tensile strength, flexural modulus, chemical resistance, dimensional stability, lightness, low moisture absorption, impact resistance, abrasion resistance, and flame retardancy. The resin constituting the core portion 31 may be a polyolefin such as polyethylene or polypropylene, as an example.

[0047] The outer layer portion 32 is formed by wrapping an inorganic fiber sheet impregnated with a thermosetting resin around the outside of the core portion 31, and then curing the thermosetting resin. Therefore, the fiber-reinforced resin constituting the outer layer portion 32 is a fiber-reinforced resin containing a thermosetting resin.

[0048] (Method for manufacturing joints) When manufacturing the joint 1A, the socket portion 2 is manufactured first. The method for manufacturing the socket portion 2 is not limited as long as it is a method that can process the material constituting the socket portion 2 into the shape of the socket portion 2. If the socket portion 2 is made of fiber-reinforced resin including thermosetting resin, the socket portion 2 can be manufactured by, for example, the hand lay-up method, filament winding method, spray-up method, BMC molding method, etc. Alternatively, the socket portion 2 may be made of thermoplastic resin and manufactured by methods such as injection molding or transfer molding. The manufactured socket portion 2 can be stored and distributed on its own, so the socket portion 2 can be manufactured at any time determined independently of the manufacturing of the joint 1A.

[0049] Next, the core portion 31 is formed. In this embodiment, the core portion 31 is formed by addition molding. The core portion 31 is extended by addition molding, using the opposite end of the receiving portion 2 manufactured in the previous step (the side that functions as a receiving port, the side that receives the pipe P when in use) as the base end. For addition molding, known apparatuses such as liquid phase photopolymerization, material injection, bonding material injection, powder bed fusion bonding, material extrusion, and sheet lamination can be used. The method and apparatus for addition molding are selected within a range in which the material constituting the core portion 31 can be molded.

[0050] A first intermediate product 41 is obtained by adding a core portion 31 with the socket portion 2 as the base end (Figure 3). As shown in Figure 2, the first intermediate product 41 has a shape corresponding to approximately half of the joint 1A, and a second intermediate product 42 is obtained in which the two socket portions 2 are connected by the core portions 31 by connecting the core portions 31 of the two first intermediate products 41 (Figure 4). The connection of the core portions 31 can be done, for example, by heat fusion. Note that both the first intermediate product 41 and the second intermediate product 42 can be stored, distributed, etc., individually.

[0051] Finally, the outer layer portion 32 is formed. For example, the outer layer portion 32 can be formed by wrapping an inorganic fiber sheet impregnated with a thermosetting resin around the outside of the core portion 31 of the second intermediate product 42, and then curing the thermosetting resin. The conditions for curing the thermosetting resin can be appropriately selected depending on the type of thermosetting resin used.

[0052] Since the second intermediate product 42 is the same as the joint 1A except that it does not have an outer layer portion 32, the angle θ between the two socket portions 2 in the joint 1A is determined when the second intermediate product 42 is completed. The size of this angle depends on the angle (θ1 in Figure 3; hereinafter referred to as the angle at the tip of the core portion 31) that the opening surface at the tip of the core portion 31 of the two first intermediate products 41 that are connected to each other makes with the extension direction of the core portion 31. In this embodiment, the angle θ1 at the tip of the core portion 31 of the two first intermediate products 41 is set to 67.5° (half of 135°), and by connecting these two, the bending angle of the core portion 31 in the second intermediate product 42 (θ2 in Figure 4) can be made to 135°.

[0053] Since the core portion 31 is formed by addition molding, the angle θ1 at the tip of the core portion 31 of the first intermediate product 41 can be changed arbitrarily and easily. Therefore, the bending angle θ2 of the core portion 31 of the second intermediate product 42 can be changed arbitrarily and easily, which means that the bending angle θ of the joint 1A can be changed arbitrarily and easily. Accordingly, according to this embodiment, a joint 1A with any bending angle θ selected according to customer requests can be easily manufactured.

[0054] Industrially used fittings have high demand for those that connect pipes in a straight line (θ = 180°) and those that connect pipes at approximately right angles (θ = 85-95°), while demand for fittings with other θ values ​​is smaller. However, from the perspective of a fitting manufacturer and seller, stocking fittings with low demand and establishing a system to easily supply them can be expected to make it easier to obtain orders for various types of fittings, including those with high demand. According to this embodiment, fittings with low demand can be manufactured in a timely manner when requested, so a wide variety of fittings can be supplied without holding excessive inventory. Therefore, this is beneficial for the entire fitting manufacturing and sales business.

[0055] Although the above describes a method for connecting two first intermediate products 41 of the same shape, it is also possible to connect first intermediate products 41 of different shapes. For example, a large number of first intermediate products 41 with a relatively versatile tip angle of 90° may be kept in stock and used as one of the first intermediate products 41, while the other first intermediate product 41 may be manufactured each time according to the bending angle of the ordered joint 1A, and the two may be connected.

[0056] [Second Embodiment] (Connection configuration) The joint 1B according to the second embodiment comprises two socket portions 2 and a main body portion 5 that connects the two socket portions 2 (Figure 5). The configuration and manufacturing method of the socket portions 2 are the same as in the first embodiment. The main body portion 5 has a core portion 51 as an inner layer portion and an outer layer portion 52 formed on the outside of the core portion 51.

[0057] The core portion 51 is manufactured as a separate cylindrical member from the receiving portion 2 and then connected to the receiving portion 2. The resin constituting the core portion 51 is not limited to any material that can form a cylindrical member. In this embodiment, the case in which the core portion 51 is manufactured by sleeve processing will be described as an example. In this case, it is preferable to use a thermoplastic resin that softens at a relatively low temperature due to its ease of molding, and for example, the core portion 51 is made of polyvinyl chloride.

[0058] The outer layer portion 52 is formed by wrapping an inorganic fiber sheet impregnated with a thermosetting resin around the outside of the core portion 51, and then curing the thermosetting resin. Therefore, the fiber-reinforced resin constituting the outer layer portion 52 is a fiber-reinforced resin containing a thermosetting resin. This point is the same as in the first embodiment.

[0059] (Method for manufacturing joints) When manufacturing the joint 1B, the socket portion 2 is manufactured first. The method for manufacturing the socket portion 2 is the same as in the first embodiment.

[0060] Next, the core portion 51 is manufactured. The core portion 51 is a cylindrical member that is pre-formed into a desired shape and can be manufactured by sleeve processing using a thermoplastic resin as the material. In this embodiment, the core portion 51 can be stored and distributed independently. Also, in this embodiment, the manufacturing of the receiving portion 2 and the manufacturing of the core portion 51 can be carried out independently.

[0061] Next, the receiving parts 2 are connected to both ends of the core part 51. Adhesive or the like may be used to secure the receiving parts 2 to the core part 51.

[0062] Finally, the outer layer portion 52 is formed. The method for forming the outer layer portion 52 is the same as in the first embodiment. That is, the outer layer portion 52 is formed by wrapping an inorganic fiber sheet impregnated with thermosetting resin around the core portion 51 after the receiving portions 2 are connected to both ends and curing it.

[0063] The angle θ between the two socket portions 2 in the joint 1B is determined by the bending angle of the core portion 51. In this embodiment, the core portion 51 is manufactured as an individual part, and molds may be used to improve efficiency. In this case, while the manufacturing efficiency of the core portion 51 is good, the shape of the resulting core portion 51 may be limited by the molds used. In other words, compared to the manufacturing method of the joint 1A, the manufacturing method of the joint 1B makes it difficult to freely change the bending angle θ as required, but it is suitable for mass production. Therefore, the manufacturing method of the joint 1B is particularly suitable for applications with relatively high demand, such as connecting pipes in a straight line (where θ is 180°) or connecting pipes at approximately right angles (where θ is around 85-95°).

[0064] [Third Embodiment] (Connection configuration) The joint 1C according to the third embodiment comprises two socket portions 71 and a main body portion 72 connecting the two socket portions 71 (Figure 6). The joint 1C has a two-layer structure throughout, with the inner layer portion 73 and the outer layer portion 74 both extending over the socket portions 71 and the main body portion 72. When the joint 1C is in use, an annular sealing material S is provided to seal the space between the inner surface of the joint 1C (socket portion 71) and the pipe P, and the socket portion 71 has a sealing material receiving groove 75 on its inner surface for accommodating the sealing material S (Figure 7).

[0065] The anti-detachment material receiving groove 22 present in the socket portion 2 of the first and second embodiments is absent in the socket portion 71 of this embodiment. By adopting a configuration without the socket portion 71, the structure of the socket portion is simpler compared to the joints of the two embodiments described above, which has the advantage of being easier to manufacture and lowering costs. The possibility of the pipe P detaching from the joint varies depending on the usage environment of the joint, etc., and if the possibility of detachment is small, the use of the anti-detachment material R is not required. In this case, it is possible to apply the joint 1C of this embodiment and obtain benefits such as cost reduction.

[0066] The inner layer portion 73 is a tubular member made of resin. The resin constituting the inner layer portion 73 is not limited to being a material that can form a tubular member. The inner layer portion 73 is understood as the core portion 51 of the second embodiment with the portion constituting the receiving portion 71 added. Therefore, it is preferable that the inner layer portion 73 be a thermoplastic resin that can be manufactured by sleeve processing or the like and softens at a relatively low temperature.

[0067] The outer layer portion 74 is formed by wrapping an inorganic fiber sheet impregnated with a thermosetting resin around the outside of the inner layer portion 73, and then curing the thermosetting resin. Therefore, the fiber-reinforced resin constituting the outer layer portion 74 is a fiber-reinforced resin containing a thermosetting resin. This point is the same as in the first and second embodiments.

[0068] (Method for manufacturing joints) When manufacturing the joint 1C, the inner layer portion 73 is manufactured first. For example, when applying sleeve processing, a sleeve pipe with an inner diameter corresponding to the finished dimensions of the main body portion 72 of the inner layer portion 73 is cut to the desired length, and sleeve processing is applied to both ends to form a shape corresponding to the inner surface of the socket portion 71. In this embodiment, the inner layer portion 73 can be stored and distributed independently.

[0069] Next, the outer layer portion 74 is formed. In the first and second embodiments, the outer layer portion was formed only on the main body portion, but in this embodiment, an integrated outer layer portion 74 is formed extending from the receiving portion 71 to the main body portion 72. Compared to the first and second embodiments, there is a difference in the extent to which the outer layer portion 74 is formed, but the method of formation itself is essentially the same; that is, the outer layer portion 74 is formed by wrapping an inorganic fiber sheet impregnated with thermosetting resin around a pre-manufactured inner layer portion 73 and curing it.

[0070] In this embodiment, the shape of the portion of the inner layer 73 corresponding to the main body 72 directly reflects the shape of the sleeve pipe used as the raw material. Therefore, the angle θ between the two socket portions 71 in the joint 1C is limited to the range in which the sleeve pipe can be processed to create the angle when manufacturing the inner layer 73, resulting in less freedom compared to the two embodiments described above. On the other hand, the number of components used is fewer than in the two embodiments described above, making it easier to manufacture compared to the two embodiments described above.

[0071] [How to use the three embodiments] Based on the differences in the characteristics of the three embodiments described above, a business that manufactures and sells fittings can, for example, use each embodiment in the following ways: For relatively inexpensive models in the company's fitting lineup that do not support the use of anti-loosening material R, the third embodiment, which is relatively easy to manufacture, can be applied to reduce manufacturing costs. For models that support the use of anti-loosening material R and have relatively high demand for angled bends (for example, those with θ around 45°, 90°, and 180°), the second embodiment can be applied to achieve both the complex shape of the socket and mass production. For models that support the use of anti-loosening material R and have relatively low demand for angled bends, the first embodiment can be applied and produced on a made-to-order basis. By having a product lineup as described above, it is possible to respond to a wide range of demands while optimizing the production system to suit the size of demand for each model, thereby increasing the overall added value of the business that manufactures and sells fittings.

[0072] [Other Embodiments] With regard to other configurations, the embodiments disclosed herein are illustrative in all respects, and it should be understood that the scope of the present invention is not limited thereto. Those skilled in the art will readily understand that modifications can be made as appropriate without departing from the spirit of the invention. Therefore, other embodiments modified without departing from the spirit of the invention are naturally included within the scope of the present invention. [Industrial applicability]

[0073] This invention can be applied to the laying of sewer pipes, agricultural water pipes, and the like. [Explanation of Symbols]

[0074] [First Embodiment] 1A: Fittings 2: Receptacle 21: Sealing material receiving groove 22: Groove for housing anti-dropping material 3: Main body 31: Core part 32: Outer layer part 41: First intermediate product 42:Second intermediate product

[0075] [Second Embodiment] 1B: Fittings 2: Receptacle 21: Sealing material receiving groove 22: Groove for housing anti-dropping material 5: Main body 51: Core part 52:Outer layer part

[0076] [Third Embodiment] 1C: Fitting 71: Receptacle 72: Main body 73: Inner layer 74:Outer layer part 75: Sealing material receiving groove

Claims

1. It comprises at least two receiving parts and a main body connecting the receiving parts, A joint having at least one main body portion comprising an inner layer made of resin and an outer layer made of fiber-reinforced resin.

2. The joint according to claim 1, wherein the inner layer portion is formed by resin addition molding.

3. The inner layer portion includes a core portion formed by adding resin with the receiving end as the base end, The joint according to claim 1, wherein the outer layer portion is formed by wrapping an inorganic fiber sheet impregnated with a thermosetting resin around the core portion and then curing the thermosetting resin.

4. The joint according to claim 1, wherein at least one of the receiving portions is made of fiber-reinforced resin.

5. The joint according to claim 1, wherein the inner layer portion extends over the main body portion and at least one of the receiving portions.

6. The joint according to claim 1, having a sealing material receiving groove on the inner surface of the receiving portion for accommodating a sealing material.

7. The joint according to any one of claims 1 to 6, wherein for at least one pair of the socket portions, the angle between the two directions in which the two socket portions extend is greater than 90° and less than 180°.

8. A method for manufacturing a joint comprising at least two socket portions and a main body portion connecting the socket portions, An inner layer forming step in which an inner layer made of resin is formed as at least part of the main body, A method for manufacturing a joint, comprising: an outer layer forming step of curing a thermosetting resin on the outside of the inner layer to form an outer layer.

9. The process further includes a step of forming a socket by curing a thermosetting resin to form at least one of the socket portions, The method for manufacturing a joint according to claim 8, wherein the inner layer forming step includes forming the inner layer portion that extends from the socket portion formed in the socket portion forming step as the base end.

10. The method for manufacturing a joint according to claim 9, wherein the inner layer forming step includes forming a core portion of the main body by adding resin with the receiving portion as the base end.

11. The method for manufacturing a joint according to claim 10, wherein the outer layer forming step includes wrapping an inorganic fiber sheet impregnated with the thermosetting resin around the core portion and then curing the thermosetting resin to form the outer layer portion.

12. The method for manufacturing a joint according to claim 8, wherein the inner layer forming step comprises forming the inner layer portion that extends over the main body portion and at least one of the receiving portions.

13. A method for manufacturing a joint according to any one of claims 9 to 12, wherein the inner layer forming step includes shrinking the resin shrink tube to form the inner layer portion.

Images