Plastic Tee Joint

Abstract

To provide a resin tees joint capable of reducing a pressure loss of fluid passing a first corner and / or a second corner without complicating a mold structure.SOLUTION: A branch part 24 of a joint main body 11 mutually connects a first straight part 21 to which an inserted first pipe 101 is connected, a second straight part 22 to which a second pipe 102 is connected, and a third straight part 23 to which a third pipe 103 is connected. A first in-core 111 to a third in-core 113 are inserted into ends of the first pipe 101 to the third pipe 103. The second branch part 24 constitutes a first corner 31 connecting the first straight part 21 and the second straight part 22 which are disposed so as to be perpendicular with each other, and a second corner 32 connecting the second straight part 22 and the third straight part 23 which are disposed so as to be perpendicular with each other. Inner portions 61 and 62 in the first and second corners 31 and 32 are formed stepwise in a flow passage direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a plastic tee joint. [Background technology]

[0002] Page A5 of Non-Patent Document 1 discloses a "tee socket (hereinafter referred to as a resin tee joint)" used for branching cold water and hot water supply piping. As shown in Fig. 6, a resin tee joint 200 includes a T-shaped joint body 201 made of synthetic resin. The joint body 201 includes a first straight portion 211 to a third straight portion 213 and a branch portion 214. The branch portion 214 connects the first straight portion 211 to the third straight portion 213 to each other.

[0003] The branched portion 214 constitutes a first corner 215 of the flow path of the resin Tee joint 200. The first corner 215 connects the first straight portion 211 and the second straight portion 212, which are arranged to be at right angles to each other. The branched portion 214 constitutes a second corner 216 of the flow path of the resin Tee joint 200. The second corner 216 connects the second straight portion 212 and the third straight portion 213, which are arranged to be at right angles to each other. The first corner 215 and the second corner 216 share the flow path on the side of the second straight portion 212. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Onda Seisakusho Co., Ltd. "General Catalog 2018-2019", pages A5, A7, and A8 Summary of the Invention [Problem to be solved by the invention]

[0005] In the first corner 215, a portion 217 located on the inside of the flow path (hereinafter referred to as the inner portion 217) forms a right angle that bends the flow of hot and cold water abruptly. In addition, in the second corner 216, a portion 218 located on the inside of the flow path (hereinafter referred to as the inner portion 218) forms a right angle that bends the flow of hot and cold water abruptly. Therefore, when hot and cold water flows between the first straight portion 211 and the second straight portion 212, or between the second straight portion 212 and the third straight portion 213, there is a problem in that a large pressure loss occurs due to the sudden change in direction of the hot and cold water at the inner portions 217, 218.

[0006] Fig. 5(b) is the result of a CAE (Computer Aided Engineering) analysis assuming that hot and cold water flows from the first straight portion 211 to the second straight portion 212 in the plastic tee fitting 200 of Fig. 6. In the analysis results, light-colored parts indicate a high flow rate of hot and cold water, and dark-colored parts indicate a low flow rate of hot and cold water. Therefore, in the analysis results, a large change from light to dark colors in the flow path direction in the inner portion 217 (see Fig. 6) indicates the occurrence of a large pressure loss. Note that the CAE analysis is performed under the assumption that the third straight portion 213 is in a sealed state.

[0007] In order to solve such problems, it is conceivable to form the inner portion 217 of the first corner 215 and the inner portion 218 of the second corner 216 by smoothly curving them in the flow path direction, similar to the corners of the "smooth elbow" described on pages A7 and A8 of Non-Patent Document 1. However, naturally, a Tee joint has more corners and a complex flow path shape compared to an elbow joint, and therefore the mold structure of the joint body 201 is complex, so it has been difficult to injection mold the inner portion 217 of the first corner 215 and the inner portion 218 of the second corner 216 with the same smoothness as the corners of the "smooth elbow".

[0008] An object of the present invention is to provide a resin tee joint that can reduce the pressure loss of a fluid passing through the first corner and / or the second corner without complicating the mold structure. [Means for solving the problem]

[0009] In order to achieve the above object, the invention of claim 1 provides a resin tee joint comprising a first straight section to be connected to a first pipe having an end thereof with a first incore inserted therein, a second straight section to be connected to a second pipe having an end thereof with a second incore inserted therein, and a third straight section to be connected to a third pipe having an end thereof with a third incore inserted therein, the branch section being integrally formed with the first to third straight sections to mutually connect the first straight section to the second straight section, the branch section forming a first corner connecting the first straight section and the second straight section which are disposed at right angles to each other, and a second corner connecting the second straight section and the third straight section which are disposed at right angles to each other, the first corner and / or the second corner having a portion located inside the flow path formed in a stepped shape along the flow path direction, and the first corner portion and / or the second corner portion forming the stepped shape being formed by exposing a tip surface of one of the first to third incores corresponding to each other to an internal space of the branch section.

[0010] According to the above configuration, at the first corner and / or the second corner, the flow of fluid in the portion located inside the flow path can be bent in multiple stages, so that the direction of the fluid is changed gradually rather than all at once, thereby reducing the pressure loss of the fluid passing through the first corner and / or the second corner.

[0011] In this way, by forming the first corner and / or second corner in a stepped shape along the flow path direction, it becomes easy to form each component for forming the stepped shape in a shape along the axial direction of the corresponding first straight portion to third straight portion, in other words, in a shape along the demolding direction of the fitting body during injection molding. In this way, the division configuration of the mold does not become complicated and the mold structure of the fitting body can be simplified compared to the case where a smoothly curved shape such as the corner of the "smooth elbow" described in the "Prior Art" is injection molded. [Brief description of the drawings]

[0012] [Figure 1] A longitudinal cross-sectional view of a plastic tee joint. [Diagram 2] FIG. [Diagram 3] Cross-sectional view taken along line AA in Figure 2. [Figure 4] Cross-sectional view of line BB in Figure 2. [Diagram 5] FIG. 4A is a diagram showing the results of CAE analysis of a plastic tee joint according to one embodiment, and FIG. 4B is a diagram showing the results of CAE analysis of a conventional plastic tee joint. [Figure 6] FIG. 1 is a longitudinal cross-sectional view of a conventional plastic tee joint. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, one embodiment of the resin tee joint of the present invention will be described. As shown in Fig. 1, the resin tee joint 1 is a branch joint for connecting a first pipe 101 on the upstream side of a cold water / hot water supply piping to a second pipe 102 and a third pipe 103 on the downstream side in a T-shape. The first pipe 101 to the third pipe 103 are made of a synthetic resin such as polybutene or cross-linked polyethylene.

[0014] As shown in Figures 1 and 2, the resin tee joint 1 comprises a T-shaped joint body 11 made of resin. The joint body 11 comprises a first straight portion 21 to a third straight portion 23 and a branch portion 24. The branch portion 24 is integrally formed with the first straight portion 21 to the third straight portion 23 so as to connect the first straight portion 21 to the third straight portion 23 to each other. Note that the resin from which the joint body 11 is made can be, for example, a mixture of polyphenylene sulfide resin and glass fiber.

[0015] As shown in Fig. 1, in the joint body 11, the first straight portion 21 and the second straight portion 22 are formed into a cylindrical shape extending linearly in directions perpendicular to each other. The branch portion 24 constitutes a first corner 31 of the flow path of the resin tee joint 1. The first corner 31 is bent at a right angle so as to connect the first straight portion 21 and the second straight portion 22. In the branch portion 24, a first corner portion 71 is formed in a portion located on the inside of the bent portion in the flow path direction.

[0016] In the joint body 11, the third straight portion 23 is formed in a cylindrical shape that is located on the same axis as the first straight portion 21 and extends linearly in a direction perpendicular to the second straight portion 22. The branched portion 24 constitutes a second corner 32 of the flow path of the resin tee joint 1. The second corner 32 is bent at a right angle so as to connect the second straight portion 22 and the third straight portion 23. In the branched portion 24, a second corner portion 72 is formed in a portion that is located inside the bent portion in the flow path direction. The first corner 31 and the second corner 32 share a flow path on the second straight portion 22 side.

[0017] The first straight portion 21 is provided with a first locking mechanism 41 that prevents the first pipe 101 connected to the first straight portion 21 from coming off. The second straight portion 22 is provided with a second locking mechanism 42 that prevents the second pipe 102 connected to the second straight portion 22 from coming off. The third straight portion 23 is provided with a third locking mechanism 43 that prevents the third pipe 103 connected to the third straight portion 23 from coming off.

[0018] A first communication port 24a is provided at the boundary between the branch portion 24 and the first straight portion 21. A second communication port 24b is provided at the boundary between the branch portion 24 and the second straight portion 22. A third communication port 24c is provided at the boundary between the branch portion 24 and the third straight portion 23.

[0019] The first straight portion 21 to the third straight portion 23 have respective accommodating portions 25 for accommodating the ends of the corresponding first pipe 101 to third pipe 103 in the inner circumferential surfaces of the first straight portion 21 to the third straight portion 23 near the branch portion 24. Steps 26 are formed between the inner circumferential surface of each accommodating portion 25 and the inner circumferential surface of the corresponding first communication port 24a to the third communication port 24c in the branch portion 24. Each step 26 is substantially perpendicular to the inner circumferential surface of the corresponding first communication port 24a to the third communication port 24c.

[0020] Cylindrical first to third incores 111 to 113 made of metal are inserted into the ends of the first to third pipes 101 to 103, respectively. The first to third incores 111 to 113 are restricted from being inserted into the corresponding first to third pipes 101 to 103 by flanges 111a to 113a formed at the ends of the first to third incores 111 to 113. The first to third pipes 101 to 103 are inserted into the accommodation portions 25 of the corresponding first to third straight portions 21 to 23 up to the positions where the tip faces of the corresponding first to third incores 111 to 113 come into contact with the step 26.

[0021] On the inner circumferential surfaces of the first straight portion 21 to the third straight portion 23, seal portions 28 having an inner diameter larger than that of the corresponding accommodating portion 25 are provided between each accommodating portion 25 and the tip end portion of the corresponding first straight portion 21 to the third straight portion 23. In each seal portion 28, a seal ring 51, a spacer 52, a seal ring 53, and a retaining ring 54 are arranged in the same order from the accommodating portion 25 side toward the tip end side of the corresponding first straight portion 21 to the third straight portion 23.

[0022] When the ends of the first pipe 101 to the third pipe 103 are inserted into the corresponding receiving portions 25 of the first straight portion 21 to the third straight portion 23, the first pipe 101 to the third pipe 103 penetrate the seal ring 51, the spacer 52, the seal ring 53, and the retaining ring 54. At this time, the seal rings 51, 53 of each seal portion 28 are in contact with the outer circumferential surfaces of the corresponding first pipe 101 to the third pipe 103, and the hot and cold water flowing through the joint body 11 is prevented from leaking out of the resin tee joint 1 from between the outer circumferential surfaces of the first pipe 101 to the third pipe 103 and the inner circumferential surface of the seal portion 28.

[0023] The first to third locking mechanisms 41 to 43 include a retaining member 44 for retaining the corresponding first to third pipes 101 to 103 on the corresponding first to third straight portions 21 to 23, and a cap 45 for attaching the retaining member 44 to the corresponding first to third straight portions 21 to 23. The retaining member 44 is provided with an annular lock ring 48 located between a fitting ring 46 and a split ring 47. Each retaining member 44 is located adjacent to a retaining ring 54 arranged in the corresponding seal portion 28.

[0024] The cap 45 is formed in a cylindrical shape. The split ring 47 and the lock ring 48 are disposed inside the cap 45, and the fitting ring 46 is further fitted inside the cap 45, so that the split ring 47 and the lock ring 48 do not fall off the cap 45. In this state, the first lock mechanism 41 to the third lock mechanism 43, each made of the retaining member 44 and the cap 45, can be easily assembled to the corresponding first straight portion 21 to the third straight portion 23 by engaging the open end of the cap 45 with the end of the corresponding first straight portion 21 to the third straight portion 23 at the portion where the open end overlaps with the end in the radial direction.

[0025] With the first locking mechanism 41 to the third locking mechanism 43 (the holding member 44 and the cap 45) attached to the corresponding first straight portion 21 to the third straight portion 23, when the ends of the first pipe 101 to the third pipe 103 penetrate the corresponding holding member 44 and the cap 45 and are inserted into the accommodation portion 25 from the tip portions of the corresponding first straight portion 21 to the third straight portion 23, the lock ring 48 of the holding member 44 presses the outer circumferential surfaces of the corresponding first pipe 101 to the third pipe 103. This makes it possible to prevent the first pipe 101 to the third pipe 103 from coming off the corresponding first straight portion 21 to the third straight portion 23.

[0026] Next, the first corner 31 and the second corner 32 will be described in detail. 1 and 4, in a portion 61 located inside the flow path of the first corner 31 (hereinafter referred to as the inner portion 61), the second communication port 24b of the branching portion 24 is located on the same axis as the corresponding second incore 112 and is formed as a partial cylinder having a diameter larger than the inner diameter of the second incore 112. Therefore, in the inner portion 61, the inner circumferential side of the tip surface of the second incore 112 is exposed to the internal space of the branching portion 24, and this exposed portion forms an angular portion 73 for the first corner.

[0027] In a portion 62 located inside the flow path of the second corner 32 (hereinafter referred to as the inner portion 62), the second communication port 24b of the branching portion 24 is located on the same axis as the corresponding second incore 112 and is formed as a partial cylinder having a diameter larger than the inner diameter of the second incore 112. Therefore, in the inner portion 62, the inner circumferential side of the tip surface of the second incore 112 is exposed to the internal space of the branching portion 24, and this exposed portion forms an angular portion 74 for the second corner.

[0028] 1 and 3, in a portion 65 located outside the first corner 31, the first communication port 24a of the branch portion 24 is located on the same axis as the corresponding first incore 111 and is formed as a partial cylinder having the same diameter as the inner diameter of the first incore 111. Therefore, in this portion 65, no step is formed in the axial direction between the inner circumferential surface of the first incore 111 and the inner circumferential surface of the first communication port 24a.

[0029] However, in the inner portion 61 of the first corner 31, the first communication port 24a of the branch portion 24 is partially cylindrically recessed so that the area obtained by projecting the internal space of the corresponding first incore 111 in the axial direction protrudes radially outward. Therefore, in the inner portion 61, the inner circumferential side of the tip surface of the first incore 111 is exposed to the internal space of the branch portion 24, and this exposed portion forms the first corner corner portion 75.

[0030] In this way, the inner portion 61 of the first corner 31 is formed in a stepped shape along the flow path direction of the first corner 31 by the multiple first corner corner portions 71, 73, 75. Therefore, when hot and cold water flows between the first straight portion 21 and the second straight portion 22, the flow of hot and cold water in the inner portion 61 can be bent in multiple stages by the multiple first corner corner portions 71, 73, 75. As a result, the direction of the hot and cold water in the inner portion 61 is changed gradually rather than all at once, and the pressure loss of the hot and cold water passing through the first corner 31 can be reduced.

[0031] Figure 5(a) shows the results of a CAE analysis under the same conditions as Figure 5(b), assuming that hot and cold water flows from the first straight section 21 to the second straight section 22 in the plastic tee fitting 1 of Figure 1. The analysis results show no significant change from light to dark in the flow path direction in the inner part 61 (see Figure 1), i.e., no significant pressure loss. It is not difficult to imagine that CAE analysis results equivalent to those in Figure 5(a) can be obtained even if it is assumed that hot and cold water flows from the second straight section 22 to the first straight section 21 in the plastic tee fitting 1 of Figure 1.

[0032] 1 and 3, in a portion 66 located outside the second corner 32, the third communication port 24c of the branch portion 24 is located on the same axis as the corresponding third incore 113 and is formed as a partial cylinder having the same diameter as the inner diameter of the third incore 113. Therefore, in this portion 66, no step is formed in the axial direction between the inner circumferential surface of the third incore 113 and the inner circumferential surface of the third communication port 24c.

[0033] However, in the inner portion 62 of the second corner 32, the third communication port 24c of the branch portion 24 is partially cylindrically recessed so that the area obtained by projecting the internal space of the corresponding third incore 113 in the axial direction protrudes radially outward. Therefore, in the inner portion 62, the inner circumferential side of the tip surface of the third incore 113 is exposed to the internal space of the branch portion 24, and this exposed portion forms the second corner portion 76.

[0034] In this way, the inner portion 62 of the second corner 32 is formed in a stepped shape along the flow path direction of the second corner 32 by the multiple second corner corner portions 72, 74, 76. Therefore, when hot and cold water flows between the second straight portion 22 and the third straight portion 23, the flow of hot and cold water in the inner portion 62 can be bent in multiple stages by the multiple second corner corner portions 72, 74, 76. As a result, the direction of the hot and cold water in the inner portion 62 is changed gradually rather than all at once, and the pressure loss of the hot and cold water passing through the second corner 32 can be reduced.

[0035] Furthermore, it is not difficult to imagine that if it is assumed that hot and cold water flows from the second straight section 22 to the third straight section 23 in the plastic tee joint 1 of Figure 1, or if it is assumed that hot and cold water flows from the third straight section 23 to the second straight section 22, it will be possible to obtain CAE analysis results equivalent to those of Figure 5(a).

[0036] Here, in the plastic tee fitting 1 of Figure 1, when the nominal diameter of the corresponding first pipe 101 to third pipe 103 is "13A", that is, when the dimensions of each component corresponding to the first straight section 21 to third straight section 23 are set to correspond to "13A", the equivalent pipe length of the plastic tee fitting 1 was measured.

[0037] According to the results of the measurements, the equivalent pipe length was 1.1 m to 1.2 m when hot and cold water flowed between the first straight portion 21 and the second straight portion 22, or when hot and cold water flowed between the second straight portion 22 and the third straight portion 23. This result indicates that the equivalent pipe length was reduced by approximately 20% compared to the conventional resin tee fitting 200 (see Figure 6) under the same conditions.

[0038] In addition, in the plastic tee fitting 1 of Figure 1, when the nominal diameter of the corresponding first pipe 101 to third pipe 103 is "16A", that is, when the dimensions of each component corresponding to the first straight section 21 to third straight section 23 are set to correspond to "16A", the equivalent pipe length of the plastic tee fitting 1 was measured.

[0039] According to the results of the measurements, the equivalent pipe length was 1.9 m to 2.0 m when hot and cold water flowed between the first straight portion 21 and the second straight portion 22, or when hot and cold water flowed between the second straight portion 22 and the third straight portion 23. This result indicates that the equivalent pipe length was reduced by approximately 20% compared to the conventional resin tee fitting 200 (see Figure 6) under the same conditions.

[0040] Furthermore, in the plastic tee fitting 1 of Figure 1, when the nominal diameters of the first pipe 101 and the third pipe 103 are "16A" and the nominal diameter of the second pipe 102 is "13A", that is, when the dimensional settings of each component corresponding to the first straight section 21 and the third straight section 23 are set to correspond to "16A" and the dimensional settings of each component corresponding to the second straight section 22 are set to correspond to "13A", the equivalent pipe length of the plastic tee fitting 1 was measured.

[0041] According to the results of the measurement, when hot and cold water flows from the first straight section 21 to the second straight section 22, or from the third straight section 23 to the second straight section 22, the equivalent pipe length was 1.0 m to 1.1 m, equivalent to the second pipe 102 on the downstream side, i.e., equivalent to a pipe with a nominal diameter of "13A". This result shows that the equivalent pipe length was reduced by approximately 20% compared to the conventional plastic tee fitting 200 (see Figure 6) under the same conditions.

[0042] In this embodiment, the following effects can be obtained. (1) By forming the inner portions 61, 62 of the first corner 31 and the second corner 32 in a stepped shape along the flow path direction, it becomes easy to form each component for forming the stepped shape in a shape along the axial direction of the corresponding first straight portion 21 to third straight portion 23, in other words, in a shape along the demolding direction of the fitting body 11 during injection molding. In this way, the division configuration of the mold does not become complicated and the mold structure of the fitting body 11 can be simplified compared to the case where a smoothly curved shape such as the corner of the "smooth elbow" described in the "Prior Art" is injection molded.

[0043] (2) The first corner portions 73, 75 and the second corner portions 74, 76 are formed by utilizing the exposed tip surfaces of the first to third incores 111 to 113. Therefore, the inner shape of the branch portion 24 can be simplified by only forming the first corner portion 71 and the second corner portion 72, and the mold structure of the joint body 11 can be further simplified.

[0044] (3) At the inner portion 61 of the first corner 31, only the inner circumferential side of the tip surface of the first incore 111 is exposed to the internal space of the branch portion 24, and the outer circumferential side of the tip surface is abutted against the corresponding step 26 and is not exposed to the internal space. In other words, even by forming the first corner corner portion 75, the abutment between the first incore 111 and the step 26 can be maintained without interruption in the circumferential direction in the annular region, and the watertightness of the entire abutment region can be maintained well. Therefore, for example, hot and cold water flowing through the branch portion 24 does not flow directly toward the seal ring 51 corresponding to the first straight portion 21, and thus a decrease in the watertightness of the resin tee joint 1 can be prevented.

[0045] The same is true for the first corner corner 73 and the second corner corner 74, which are formed by utilizing the exposed tip surface of the second incore 112, and the second corner corner 76, which is formed by utilizing the exposed tip surface of the third incore 113, and similarly, hot and cold water can be prevented from flowing directly toward the seal ring 51 corresponding to the second straight portion 22 or the seal ring 51 corresponding to the third straight portion 23.

[0046] <Another example> The present invention can also be implemented in the following manner, for example. For only one of the first corner 31 and the second corner 32, the corresponding inner portion 61, 62 may be formed in a stepped shape along the flow path direction.

[0047] The first corner portions 73, 75 and the second corner portions 74, 76 are removed, and the first corner portion 71 and the second corner portion 72 are each formed in a stepped shape (multiple corners) along the flow path direction.

[0048] In the above embodiment, the flow of hot and cold water in the inner portion 61 of the first corner 31 was bent in three stages (three first corner corner portions 71, 73, 75), but this can be changed to a configuration in which the flow of hot and cold water is bent in multiple stages other than three stages, such as two stages, four stages, five stages, six stages, etc.

[0049] In the above embodiment, the flow of hot and cold water in the inner portion 62 of the second corner 32 was bent in three stages (three second corner corner portions 72, 74, 76), but this can be changed to a configuration in which the flow of hot and cold water is bent in multiple stages other than three stages, such as two stages, four stages, five stages, six stages, etc.

[0050] The present invention may be implemented in a resin tee joint having a structure that branches in three or more directions.

[0051] Next, the technical concept that can be understood from the above embodiment will be described. (A) A resin joint body having a branch portion integrally formed with the first straight portion to the third straight portion so as to mutually connect a first straight portion to which a first pipe made of polybutene or cross-linked polyethylene having a first incore inserted into an end thereof is connected, a second straight portion to which a second pipe made of polybutene or cross-linked polyethylene having a second incore inserted into an end thereof is connected, and a third straight portion to which a third pipe made of polybutene or cross-linked polyethylene having a third incore inserted into an end thereof is connected, the branch portion defines a first corner connecting the first straight portion and the second straight portion that are disposed at right angles to each other, and defines a second corner connecting the second straight portion and the third straight portion that are disposed at right angles to each other, At the first corner and / or the second corner, a portion located inside the flow path is formed in a stepped shape along the flow path direction, The first corner portion and / or the second corner portion forming the stepped shape are formed by exposing the tip surface of one of the corresponding first to third incores to the internal space of the branch portion, forming a resin tee joint. [Explanation of symbols]

[0052] 1...plastic tee fitting, 11...fitting body, 21...first straight portion, 22...second straight portion, 23...third straight portion, 24...branch portion, 31...first corner, 32...second corner, 61...inner portion, 62...inner portion, 71...corner for first corner, 72...corner for second corner, 73...corner for first corner, 74...corner for second corner, 75...corner for first corner, 76...corner for second corner, 101...first pipe, 102...second pipe, 103...third pipe.

Claims

[Claim 1] a resin joint body having a branch portion integrally formed with the first straight portion to the third straight portion, so as to mutually connect a first straight portion to which a first pipe having a first incore inserted into an end thereof is connected, a second straight portion to which a second pipe having a second incore inserted into an end thereof is connected, and a third straight portion to which a third pipe having a third incore inserted into an end thereof is connected; the branch portion defines a first corner connecting the first straight portion and the second straight portion that are disposed at right angles to each other, and defines a second corner connecting the second straight portion and the third straight portion that are disposed at right angles to each other, At the first corner and / or the second corner, a portion located inside the flow path is formed in a step shape along the flow path direction. the first corner portion and / or the second corner portion forming the stepped shape are formed by exposing a tip surface of one of the first inner core and the third inner core corresponding to the tip surface to an internal space of the branch portion, A resin tee joint in which the first corner and / or the second corner are formed in a stepped shape by exposing the corresponding tip surfaces of the first and third incores, and in a portion located outside the flow path, the tip surface is not exposed to the internal space of the branching portion, and therefore no step is formed in that portion due to the exposure of the tip surface.

Images