Connection device of resin pipe

Abstract

To improve strength of a connection device of a resin pipe.SOLUTION: A connection device 5 includes an upper split body 10, a lower split body 20, hinge means H for rotatably coupling one end portions of the split bodies 10, 20, and fastening means 30 for fastening the other end portions of the split bodies 10, 20 so as to come close to each other. Fitting grooves 12, 22 are formed on inner peripheries of body portions 11, 21 of the split bodies 10, 20. At the time of fastening, tapered surfaces 12x, 22x of the fitting grooves 12, 22 are abutted to tapered surfaces 1y, 2y of flange portions 1a, 2a of resin pipes 1, 2, and thereby, flanges 1a, 2a of the resin pipes 1, 2 are abutted with each other. The split bodies 10, 20 mainly consist of glass fiber reinforced nylon. In the first and the second split bodies 10, 20, a hydrophobic layer made of an acrylic resin, an ethylene-vinyl acetate resin, an urethane resin, etc., is formed on inner peripheries coming into contact with the resin pipes 1a, 2a (including inner surfaces of the fitting grooves 12, 22) and end facing surfaces.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a device for connecting two plastic pipes each having a flange portion at one end. [Background technology]

[0002] When it is required to connect plastic pipes without fusing at the construction site of water supply piping, a plastic pipe with flanges at the end is manufactured in the factory by butt fusing a short pipe with a flange to a long plastic pipe body. The flange has a butt joint surface at the tip that is perpendicular to the axis of the plastic pipe and a tapered surface on the opposite side. At the construction site, a connecting device is used to connect the flanges of the two plastic pipes by butting them together.

[0003] As shown in Patent Documents 1 and 2, the connection device includes a pair of half-split divided bodies, a hinge means for rotatably connecting one end of the pair of divided bodies to each other, and a fastening means for tightening the other end of the pair of divided bodies so as to bring them closer to each other. A fitting groove is formed on the inner periphery of each of the pair of divided bodies, and a tapered surface is formed on both sides of the fitting groove, the tapered surface having the same taper angle as the tapered surface of the flange portion of the plastic pipe.

[0004] To briefly explain the process of connecting plastic pipes using the connecting device, the pair of divided bodies are opened, and the flanges of the two plastic pipes are placed in the fitting grooves of the lower divided body. Next, the upper divided body is rotated in the closing direction around the hinge means, and the flanges of the two plastic pipes are loosely fitted into the fitting grooves. Finally, when the two divided bodies are tightened by the tightening means, the tapered surfaces on both sides of the fitting groove come into contact with the tapered surfaces of the flanges of the two plastic pipes, and the tightening force is converted into an axial force that brings the flanges of the two plastic pipes closer together. As a result, the two plastic pipes are connected with the butt surfaces of the flanges coming into contact. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5740123 [Patent Document 2] Patent Publication No. 2021-50789 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 2, the strength is increased by using glass fiber reinforced resin as the main raw material of the divided bodies. When glass fiber reinforced polypropylene (GFPP) is used as the main raw material of the glass fiber reinforced resin, thermal degradation occurs when high-temperature water flows through the pipe, and the strength decreases. When glass fiber reinforced nylon (GFPA) is used as the main raw material for the segments, it has high strength and does not lose strength due to thermal degradation. However, nylon absorbs water, which causes a decrease in strength, which is an obstacle when used for water supply piping. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a device for connecting two plastic pipes having an annular flange portion at one end, comprising: The present invention comprises first and second divided bodies, hinge means for rotatably connecting one ends of the first and second divided bodies to each other along a plane perpendicular to the axis of the plastic pipe, and fastening means for fastening the other ends of the first and second divided bodies so as to bring them closer together while the first and second divided bodies sandwich the flange portions of the two plastic pipes, wherein an arc-shaped mating groove is formed on the inner circumference of the first and second divided bodies, and the inner surface of the mating groove has tapered surfaces on both sides, and when fastened by the fastening means, the tapered surfaces of the mating groove come into contact with the tapered surfaces formed on the flange portions of the two plastic pipes, thereby causing the flange portions of the two plastic pipes to be butted against each other, and the first and second divided bodies are made primarily of glass fiber reinforced nylon, and a hydrophobic layer is formed on at least the inner surface of the mating groove of the first and second divided bodies.

[0008] According to the above configuration, the first and second halves are made of glass fiber reinforced nylon as the main material, which increases the strength of the halves, and even if high-temperature water flows through the resin pipe, the strength does not decrease due to thermal degradation. In addition, the hydrophobic layer is formed on the inner surface of the fitting groove, which is likely to come into contact with water, so that the glass fiber reinforced nylon in the fitting groove can be prevented from absorbing water, and the strength does not decrease due to water absorption. As a result, the device can be used as a connecting device for water supply piping.

[0009] Preferably, the inner periphery of the first and second divided bodies has a cylindrical pipe portion pressing surface adjacent to both axial sides of the fitting groove, and in the tightened state, the pipe portion pressing surface presses the outer circumferential surface of the pipe portion adjacent to the flange portion of the plastic pipe, and the hydrophobic layer is also formed on the pipe portion pressing surface. According to the above-mentioned configuration, water absorption by the glass fiber reinforced nylon can be prevented even on the pipe pressing surface with which water may come into contact.

[0010] Preferably, the hydrophobic layer is also formed on opposing surfaces of circumferential ends of the first and second divided bodies. According to the above-mentioned configuration, water absorption by the glass fiber reinforced nylon can be prevented even at the end facing surfaces with which water may come into contact.

[0011] Preferably, the hydrophobic layer is formed on the entire outer surfaces of the first and second divided bodies. According to this configuration, the glass fibers protruding from the outer surfaces of the first and second segments can be covered, improving the appearance.

[0012] Preferably, the hydrophobic layer is provided as a primer, with a paint applied thereon. According to the above-mentioned configuration, the appearance can be further improved by applying paint.

[0013] The hydrophobic layer contains at least one of an acrylic resin, an ethylene vinyl acetate resin, and a urethane resin. The hydrophobic layer has a thickness of 10 μm or more. Effect of the Invention

[0014] According to the present invention, high strength can be maintained even when used to connect resin pipes that constitute water supply piping. [Brief description of the drawings]

[0015] [Figure 1] 1 is a perspective view showing a plastic pipe connecting device according to an embodiment of the present invention in a state where the connection of the plastic pipes has been completed, with the connecting device and the plastic pipes being partially cut away. FIG. [Diagram 2] FIG. 2 is a perspective view showing a pair of upper and lower divided bodies of the connection device in a separated state, in which each of the pair of divided bodies is cut in half in the width direction and viewed from different directions. [Diagram 3] FIG. 4 is a cross-sectional view showing the pair of split bodies in a separated state. [Figure 4] 5A and 5B are cross-sectional views sequentially showing a process of connecting plastic pipes using the connecting device, in which (A) shows a state during the connecting process, and (B) shows a state after the connecting process is completed, with the plastic pipes omitted. [Diagram 5] 5A and 5B are longitudinal cross-sectional views sequentially illustrating a process of connecting a resin pipe using the connecting device, in which (A) shows a state during the connecting process, and (B) shows a state after the connecting process is completed. [Figure 6] FIG. 4 is an enlarged cross-sectional view of a hydrophobic layer formed on the divided body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Plastic pipe structure First, referring to Figures 1 and 5, the plastic pipes 1 and 2 of the water supply piping to be connected will be described. The plastic pipes 1 and 2 are made of a resin such as polyethylene, and have annular flanges 1a and 2a at one end. The tip surfaces of the flanges 1a and 2a form mating surfaces 1x and 2x that are perpendicular to the axis L, and the surfaces on the opposite side form tapered surfaces 1y and 2y. An annular groove 1z is formed in the mating surface 1x of the flange 1a of one of the plastic pipes 1, and an O-ring 3 is fitted into this annular groove 1z. The resin pipes 1, 2 are manufactured by butt welding a short pipe having the flanges 1a, 2a to a long resin pipe body.

[0017] A short cylindrical incore 4 is disposed on the inner circumference of one end of each of the plastic pipes 1 and 2. The incore 4 is made of stainless steel such as SUS304, and has an annular flange 4a that protrudes radially and outwardly at one end. This flange 4a engages with annular recesses 1b and 2b formed on the inner circumference of the tip of the plastic pipes 1 and 2, so that the incore 4 is attached to the plastic pipes 1 and 2 with its axial movement restricted. Because the flange 4a is housed in the recesses 1b and 2b, it does not interfere with the butting of the flanges 1a and 2a, which will be described later.

[0018] Configuration of connected devices Next, a description will be given of the connection device 5 for connecting the resin pipes 1, 2. The connection device 5 has a pair of upper and lower division bodies, that is, an upper division body 10 (first division body) and a lower division body 20 (second division body). The division bodies 10, 20 are made mainly of glass fiber reinforced nylon, and have main bodies 11, 21 each having a substantially semi-cylindrical shape.

[0019] The main body portions 11, 21 of the divisional bodies 10, 20 have a circumferential dimension slightly shorter than that of a complete semicylinder. That is, as shown in Fig. 3, both circumferential end faces 11x, 11y (end-facing surfaces) of the main body portion 11 of the upper divisional body 10 are slightly set back from a plane P passing through the radial center C of the inner circumference of the main body portion 11 and are parallel to this plane P. Similarly, the circumferential end faces 21x, 21y (end-facing surfaces) of the main body portion 21 of the lower divisional body 20 are slightly set back from a plane P' passing through the radial center C' of the inner circumference of the main body portion 21 and are parallel to this plane P'.

[0020] The inner periphery of the main body 11, 21 of the divided body 10, 20 has a fitting groove 12, 22 extending in a substantially semicircular shape in the circumferential direction and a semicylindrical pipe pressing surface 13, 23 adjacent to both axial sides of the fitting groove 12, 22. The diameter of the pipe pressing surface 13, 23 is equal to the outer diameter of the pipe of the resin pipe 1, 2 (excluding the flanges 1a, 2a). The inner surface of the fitting groove 12, 22 has tapered surfaces 12x, 22x on both sides, and a bottom surface 12y, 22y in the center that forms a semi-cylindrical surface with a diameter larger than that of the pipe portion pressing surface 13, 23. The taper angle of the tapered surfaces 12x, 22x is equal to that of the tapered surfaces 1y, 2y of the flange portions 1a, 2a of the plastic pipes 1, 2. The diameter of the bottom surfaces 12y, 22y is equal to the outer diameter of the flange portions 1a, 2a. The cross-sectional shape of the fitting groove 12, 22 is approximately equal to that of the flange portions 1a, 2a when the butt surfaces 1x, 2x of the flange portions 1a, 2a are in contact with each other, as described later.

[0021] An engagement portion 15 is provided integrally with the main body 11 at one circumferential end of the main body 11 of the upper half body 10. The engagement portion 15 has a protrusion 15a that protrudes radially outward from one end of the main body 11, and an extension 15b that extends downward (toward the lower half body 20) from the tip of the protrusion 15a, beyond the end face 11x, and perpendicular to the end face 11x. The lower surface of the protrusion 15a forms an end-facing surface 15x that is flush with the end face 11x of the main body 11.

[0022] An engagement hole 16 is formed in the engagement portion 15 of the upper half body 10. This engagement hole 16 has a main hole portion 16a formed in the extension portion 15b and penetrating in the radial direction, and an escape recess portion 16b formed in the protrusion portion 15a and connected to the main hole portion 16a. The main hole portion 16a is substantially rectangular and occupies a portion between a lower surface 16x of the engagement hole 16 and an imaginary extension surface of the end opposing surface 15x. This lower surface 16x serves as a load receiving surface, as will be described later. The relief recess 16b is located above the imaginary extension plane of the end opposing surface 15x (opposite the lower division body 20) and is open only radially outward. The horizontal dimension of the relief recess 16b is equal to the horizontal dimension of the main hole portion 16a.

[0023] An engagement protrusion 25 extending radially outward is formed integrally with the main body 21 at one circumferential end of the main body 21 of the lower half body 20. The cross-sectional shape of the engagement protrusion 25 is rectangular, and its upper surface forms an end opposing surface 25x that is flush with the end surface 21x of the main body 21. The vertical and horizontal dimensions of the engagement protrusion 25 are slightly shorter than the vertical and horizontal dimensions of the main hole portion 16a of the engagement hole 16 of the upper half body 10. As described later, the engagement protrusion 25 of the lower divisional body 20 is inserted into the engagement hole 16 of the upper divisional body 10 to form a hinge means H. This hinge means H connects the upper divisional body 10 to the lower divisional body 20 so as to be rotatable relative to each other along a plane perpendicular to the axis L of the resin pipes 1, 2.

[0024] Support parts 18, 28 protruding radially outward are formed integrally with the main body parts 11, 21 at the other circumferential end parts of the main body parts 11, 21 of the divided bodies 10, 20. The support parts 18, 28 have end facing surfaces 18x, 28x that are flush with the end faces 11y, 21y of the main body parts 11, 21. Through holes 18a, 28a are formed in the support parts 18, 28. A pair of anti-rotation projections 29 are formed on the underside of the support part 28 and located on both sides of the through hole 28a. As shown in FIG. 4(B), fastening means 30 for fastening the supports 18 and 28 includes a bolt 31 and a nut 32.

[0025] Plastic pipe connection process using a connection device The process of connecting the plastic pipes 1, 2 using the connecting device 5 will now be described. As shown in Figures 4(A) and 5(A), first, the flange portions 1a, 2a of the plastic pipes 1, 2 are placed on the lower divided body 20 with the O-ring 3 brought close enough to lightly contact the abutting surface 2x of the plastic pipe 2. The flange portions 1a, 2a are aligned with the fitting groove 22, and a part of them is received in the fitting groove 22.

[0026] Next, the upper half body 10 is moved laterally toward the lower half body 20 while still in an inclined position, and the engagement protrusion 25 is inserted into the engagement hole 16 of the engagement portion 15. At this time, a part of the tip of the engagement protrusion 25 comes out of the main hole portion 16a of the engagement hole 16, but can be received in the relief recess 16b.

[0027] Next, the upper division body 10 is rotated about the fulcrum F (the point where one end of the load-receiving surface 16x contacts the underside of the engaging protrusion 25) so as to move closer to the lower division body 20, whereby the support portion 18 of the upper division body 10 moves closer to and faces the support portion 28 of the lower division body 20. In this state, parts of the flange portions 1a, 2a are also accommodated in the fitting groove 12 of the upper division body 10. In addition, the engaging protrusion 25 of the lower division body 20 fits within the main hole portion 16a of the engaging hole 16 of the upper division body 10.

[0028] Next, with the nut 32 fitted between the pair of anti-rotation projections 29 so as not to rotate, the bolt 31 is passed through the through holes 18a, 28a of the support parts 18, 28 of the division bodies 10, 20, screwed into the nut 32, and turned in the tightening direction, as shown in FIG. 4(B). As a result, the flange parts 1a, 2a of the resin pipes 1, 2 are clamped between the lower division body 20 and the upper division body 10 and tightened. This tightening force is converted into an axial force that moves the flange parts 1a, 2a closer to each other by the action of the tapered surfaces 12x, 22x on both sides of the fitting grooves 12, 22 and the tapered surfaces 1y, 2y of the flange parts 1a, 2a. As a result, as shown in FIG. 5(B), the butt surfaces 1x, 2x of the flange parts 1a, 2a come into surface contact with each other with the elastic deformation of the O-ring 3. In this way, the connection process is completed.

[0029] Tightening the bolt 31 brings the support parts 18, 28 closer to each other, and a force acts in the direction in which the opposite sides move apart. Therefore, the engagement protrusion 25 strongly hits the load-receiving surface 16x of the engagement hole 16 of the engagement part 15. This allows the lower division body 20 and the upper division body 10 to strongly tighten the flange parts 1a, 2a.

[0030] In the above-mentioned fastened state, the inner surfaces of the fitting grooves 12, 22, i.e., the tapered surfaces 12x, 22x and the bottom surfaces 12y, 22y, contact the tapered surfaces 1y, 2y and the outer peripheral surfaces of the flange portions 1a, 2a of the plastic pipes 1, 2, respectively, and the pipe portion pressing surfaces 13, 23 contact the outer peripheral surfaces of the pipe portions adjacent to the flange portions 1a, 2a in the plastic pipes 1, 2. Also, in this fastened state, the end faces 11x, 11y of the main body portion 11 of the upper division body 10 and the end faces 21x, 21y of the main body portion 21 of the lower division body 20 face each other closely, the engaging portion 15 of the hinge means H and the end facing surfaces 15x, 25x of the engaging projection 15 face each other closely, and the end facing surfaces 18x, 28x of the supporting portions 18, 28 face each other closely.

[0031] Formation of a hydrophobic layer The divided bodies 10 and 20 are injection molded products made mainly of glass fiber reinforced nylon. Therefore, they have high strength and can maintain their high strength without thermal degradation even when high-temperature water flows through the water supply pipe. However, nylon is water absorbent, and there is a risk of strength loss due to water absorption. For example, when it absorbs about 1 to 5% water, the strength decreases by up to 50% compared to the bone dry state. Therefore, in this embodiment, a hydrophobic layer 50 (see FIG. 6) is formed on the surface of the divided bodies 10, 20 that may come into contact with water if a small amount of water leakage occurs from the joint of the resin pipes 1, 2. This hydrophobic layer 50 is formed by applying a resin containing at least one of an acrylic resin, an ethylene vinyl acetate resin, and a urethane resin by spraying. The hydrophobic layer 50 has a thickness of 5 to 30 μm, and more preferably a thickness of 10 to 30 μm.

[0032] In this embodiment, a hydrophobic layer 50 is formed on the entire inner periphery of the divided bodies 10, 20 which contact the resin pipes 1, 2 and on the faces which are close to and opposed to each other. The inner periphery of the divided bodies 10, 20 includes the inner surfaces of the fitting grooves 12, 22 (that is, the tapered surfaces 12x, 22x and the bottom surfaces 12y, 22y) and the pipe portion pressing surfaces 13, . The adjacent opposing surfaces of the divided bodies 10, 20 include end surfaces 11x, 11y, 21x, 21y of the main bodies 11, 21 and end opposing surfaces 15x, 25x, 18x, 28x.

[0033] As described above, the hydrophobic layer 50 is formed on the inner periphery and opposing surfaces of the divided bodies 10, 20, so that the glass fiber reinforced nylon of the divided bodies 10, 20 can be prevented from absorbing water, thereby preventing a decrease in strength due to water absorption and allowing high strength to be maintained.

[0034] experiment Two types of dumbbell-shaped glass fiber reinforced nylon test pieces of the same size were prepared. Test piece (1) had the above hydrophobic layer of 10 to 20 μm formed thereon, and test piece (2) had no hydrophobic layer formed thereon. A creep test was carried out on both test pieces in warm water at 80°C, and the rupture times were compared, with the results shown in Table 1 below. From Table 1, the effect of the hydrophobic layer was confirmed. [Table 1]

[0035] The hydrophobic layer 50 may be formed only on the inner surfaces of the fitting grooves 12, 22 which are most likely to come into contact with water. Moreover, the hydrophobic layer 50 may be formed on the entire outer surfaces (exposed surfaces) of the divided bodies 10 and 20. When glass fiber reinforced nylon is injection molded, minute fibers protrude from the outer surface of the molded product, marring the appearance. However, by covering these with the hydrophobic layer 50, the appearance can be improved.

[0036] When the hydrophobic layer 50 is formed on the entire outer surface of the divided bodies 10, 20, the appearance can be further improved by using a primer for the hydrophobic layer and applying paint 60 (see FIG. 6) over the entire surface of the primer.

[0037] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the hinge device may include an axis member, a link, etc. that are separate from the first and second divisional bodies. The fastening means can also be modified in various ways. [Industrial Applicability]

[0038] The present invention can be applied to an apparatus for connecting plastic pipes having flanges at their ends. [Explanation of symbols]

[0039] 1, 2 Plastic pipe 1a, 2a Flange section 1x, 2x butt faces 1y, 2y tapered surface 5 Connecting Devices 10 Upper division body (first division body) 20 Lower divided body (second divided body) 11x, 11y, 21x, 21y End faces of main body (opposite end faces) 12, 22 Fitting groove 12x, 22x tapered surface 12y, 22y bottom 13, 23 Pipe clamping surface 15x, 25x, 18x, 28x End facing surface 30 Fastening means 50 Hydrophobic layer 60 paint H Hinge Means

Claims

1. The pipe end of each of the two resin pipes is butted against each other at annular flange portions, and a first and a second divided body are provided to cover the flange portions from an outer circumferential side. A resin pipe connecting device, comprising a hydrophobic layer on the inner surface of the first and second divided bodies.

2. 2. The resin pipe connecting device according to claim 1, wherein the first and second divided bodies are also provided with hydrophobic layers on their opposing surfaces.

3. 3. The resin pipe connecting device according to claim 1, wherein the hydrophobic layer is also formed on the outer surfaces of the first and second divided bodies.

4. The resin pipe connecting device according to claim 1 , wherein the hydrophobic layer is a primer.

5. 5. The resin pipe connecting device according to claim 1, wherein the hydrophobic layer contains at least one of an acrylic resin, an ethylene vinyl acetate resin, and a urethane resin.

6. 6. The resin pipe connecting device according to claim 1, wherein the hydrophobic layer has a thickness of 5 [mu]m or more.

7. 7. The plastic pipe connecting device according to claim 1, wherein the first and second divided bodies are made mainly of glass fiber reinforced nylon.

8. The resin pipe connecting device according to any one of claims 1 to 7, A water supply piping having a resin pipe connected to the resin pipe connection device.

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