Watertight structure of pipe joints and rubber rings used therefor

Abstract

To provide a water cut-off structure for a pipe joint enabling excellent construction performance and reconstruction without deteriorating water-tightness and a rubber ring used for the water cut-off structure.SOLUTION: A rubber ring 4 includes: a cylindrical-shaped cylindrical part having a tip part 41a inserted into a first space part; a tapered part 42 of which outer diameter expands from the other end part 41b side of the cylindrical part toward a direction opposite to the tip part 41a; and a reception part that receives a rubber packing 6. An inner diameter of the cylindrical part is larger than an outer diameter of an insertion port 3, and the tapered part 42 is formed so that wall thickness thereof gradually becomes thin from the other end part 41b to the tapered tip part. A push ring 5 pushes the rubber packing 6 against an end surface of the other end part 41b and an inner surface 42a of the tapered part 42. The tip part 41a of a rubber ring 4 is brought into close contact with an inner surface 21a of the first space part, and an outer surface 42b of the tapered part 42 is brought into close contact with an inner surface of a second space part.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a watertight structure for a pipe joint and a rubber ring used therein. More specifically, the invention relates to a watertight structure for a pipe joint in which the spigot of another pipe is inserted into the spigot of a ductile cast iron pipe, and a rubber ring attached to the outer surface of the spigot is pressed against the spigot by a pressure ring to stop water flow. [Background technology]

[0002] Conventionally, a watertight structure for a pipe joint such as the one described above is known, for example, from Patent Document 1. This watertight structure for a pipe joint for ductile cast iron pipes uses a rubber ring 4' as shown in Figure 9. Because the inner diameter D0 of this rubber ring 4' is smaller than the outer diameter of the insertion port 3, during installation, a lubricant or the like must be applied to the outer surface of the insertion port 3 and the inner surface of the rubber ring 4', and the rubber ring 4' must then be expanded and attached, making the work complicated.

[0003] Furthermore, one end of this rubber ring 4' has a rounded portion 4'a, and as shown in Figure 9, when the rubber ring 4' is attached to the insertion port 3, the outer diameter of the rounded portion 4'a is larger than the inner diameter of the first space 21' of the socket 2. Therefore, even if a lubricant is applied, it is difficult to press the rounded portion 4'a into the first space 21' with the press ring 5. Even if it is pressed in, the rubber ring 4' will pull the insertion port 3 further into the socket 2 than the intended joint position, requiring skilled technique to align the connection. Furthermore, when re-installing, even if the T-head bolt 9a and nut 9b are removed and the pipe fitting is disassembled, it is difficult to remove the insertion port 3 and the pressed-in rubber ring 4' from the socket 2. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 6-69574 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above-described conventional situation, the present invention aims to provide a water-stopping structure for a pipe joint that is easy to install and can be reinstalled without compromising watertightness, and a rubber ring to be used therewith. [Means for solving the problem]

[0006] In order to achieve the above object, the watertight structure of a pipe joint according to the present invention is characterized in that the outlet of another pipe is inserted into the outlet of a ductile cast iron pipe, and a rubber ring attached to the outer surface of the outlet is pressed against the outlet by a pressure ring to seal the water, and an annular rubber packing is further provided between the rubber ring and the pressure ring to be attached to the outer circumferential surface of the outlet, and the outlet has a cylindrical first space portion and a second space portion whose inner diameter expands from the first space portion towards the opening, and the rubber ring has a cylindrical portion whose tip portion is inserted into the first space portion and a second space portion whose inner diameter expands from the other end side of the cylindrical portion in the opposite direction to the tip portion. It is provided with a tapered portion whose diameter expands, and a receiving portion that receives the rubber packing and is composed of the end face of the other end of the cylindrical portion and the inner surface of the tapered portion, the inner diameter of the cylindrical portion being larger than the outer diameter of the insertion port, and the tapered portion is formed so that its thickness gradually decreases from the other end toward the tapered tip, and the pressure ring presses the rubber packing against the end face of the other end and the inner surface of the tapered portion, and causes the tip of the rubber ring to adhere to the inner surface of the first space portion and the outer surface of the tapered portion to adhere to the inner surface of the second space portion.

[0007] According to the above configuration, an annular rubber gasket is further provided between the rubber ring and the press ring and attached to the outer periphery of the spigot. The spigot has a cylindrical first space and a second space whose inner diameter expands from the first space toward the opening. The rubber ring has a cylindrical portion whose tip is inserted into the first space, a tapered portion whose outer diameter expands from the other end of the cylindrical portion toward the opposite direction from the tip, and a receiving portion formed by the end face of the other end of the cylindrical portion and the inner surface of the tapered portion for receiving the rubber gasket. The inner diameter of the cylindrical portion is larger than the outer diameter of the spigot, and the tapered portion is formed so that its wall thickness gradually decreases from the other end toward the tapered tip. This allows installation without the application of a lubricant, and the spigot can be inserted in a pre-assembled state, as shown in Figure 6, for example, resulting in extremely high workability. Furthermore, because the tip can be attached (inserted) so that it fits along the first space, the insertion port will not be pulled further into the receiving port than the intended joining position when pressed (joined) with the press ring. Furthermore, by gradually thinning the tapered portion toward the tapered tip, the boundary (base) between the tip of the cylindrical portion and the tapered portion is thick. This ensures the strength of the tip and makes it easy to insert and remove the tip into the first space. Furthermore, due to the shape of the tapered portion, the press ring presses the rubber packing against the end face of the other end and the inner surface of the tapered portion, so that the tip of the rubber ring adheres to the inner surface of the first space and the outer surface of the tapered portion adheres to the inner surface of the second space. This compresses and deforms the rubber packing along the tapered surface, ensuring watertightness.

[0008] In the above configuration, the outer diameter of the tip of the cylindrical portion is preferably slightly larger than the inner diameter of the first space portion, and the outer diameter of the tapered portion is preferably slightly larger than the inner diameter of the second space portion. This eliminates the need to reduce the diameter of the cylindrical portion and the tapered portion when fitting the rubber ring into the socket. Because the rubber ring is fitted with reduced diameters, it is temporarily fixed to the socket by repulsive force after fitting. This eliminates the need to hold the rubber ring down after fitting, improving workability.

[0009] In this configuration, the tapered tip may have a locking portion that locks onto the outer edge of the socket and a bulging portion that bulges inward from the locking portion, making it easier to keep the rubber packing concentric with other components during work.

[0010] In the above configuration, the inner surface of the bulge may be tapered so that the inner diameter of the bulge narrows outward. This allows the inner surface of the bulge to be flat after the rubber ring is attached to the receiving port, and does not interfere with insertion of the spigot, improving workability.

[0011] In the above configuration, the rubber ring may be made of a rubber material that is equal to or harder than the rubber packing, so that the pressure of the pressure ring mainly compresses and deforms the rubber packing, reducing its diameter and ensuring watertightness.

[0012] In this configuration, the rubber packing has a front surface facing the inner surface of the tapered portion and an inner peripheral surface facing the outer peripheral surface of the pipe, and the front surface and the inner peripheral surface preferably have a plurality of annular ridges at appropriate intervals. This allows the annular ridges to compress and deform, reducing the overall diameter of the rubber packing and ensuring close contact with the rubber ring and the spigot, ensuring strong watertightness. In this case, the inclination angle of the inner surface of the tapered portion relative to the cylindrical portion may be greater than the inclination angle of the outer surface of the tapered portion relative to the cylindrical portion. In this configuration, increasing the inclination angle of the inner surface of the tapered portion promotes rolling of the compressive deformation of the ridges on the front surface, facilitating diameter reduction. Furthermore, the large inclination angle of the inner surface prevents the rubber packing from clogging in front of the rubber ring receiving portion and facilitates disassembly.

[0013] In the above configuration, the outer surface of the tapered portion may be provided with a plurality of annular protrusions at appropriate intervals, so that even if the tapered surface of the socket is scratched, the annular protrusions can deform to fill the gaps caused by the scratch, ensuring watertightness.

[0014] In any of the above configurations, the socket of the ductile cast iron pipe is a K-type socket or a socket similar to a K-type socket. A socket similar to a K-type socket is, for example, any of an NS-type, an S-type, a US-type, a UF-type, and a U-type socket. In the present invention, the term "ductile cast iron pipe" also includes a deformed ductile cast iron pipe.

[0015] In order to achieve the above-mentioned object, the rubber ring of the present invention is characterized in that, in a configuration used in a water-stopping structure of a pipe fitting in which the spigot of another pipe is inserted into the spigot of a ductile cast iron pipe, the spigot has a cylindrical first space portion and a second space portion whose inner diameter expands from the first space portion toward the opening, and the rubber ring has a cylindrical cylindrical portion whose tip portion is inserted into the first space portion, a tapered portion whose outer diameter expands from the other end side of the cylindrical portion in the direction opposite the tip portion, and a receiving portion formed by the end face of the other end of the cylindrical portion and the inner surface of the tapered portion for receiving an annular rubber gasket to be attached to the outer surface of the spigot, the inner diameter of the cylindrical portion is larger than the outer diameter of the spigot, and the tapered portion is formed so that its thickness gradually becomes thinner from the other end toward the tapered tip portion. [Effects of the Invention]

[0016] The features of the watertight structure for a pipe joint and the rubber ring used therein according to the present invention provide excellent workability and re-workability without reducing watertightness.

[0017] Other objects, configurations and effects of the present invention will become apparent from the following detailed description of the preferred embodiments of the present invention. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view showing a waterproof structure for a pipe connection according to the present invention; [Figure 2] 1 is a perspective view of a rubber ring according to the present invention. [Figure 3] FIG. 1 is an enlarged longitudinal cross-sectional view of a rubber ring. [Figure 4] FIG. [Figure 5] This is a view equivalent to Figure 4 showing the state in which a rubber ring is attached to the receiving port. [Figure 6] This is an enlarged partial cross-sectional view showing the state in which the rubber gasket and the press ring are temporarily assembled to the receiving port with the rubber ring attached. [Figure 7] 7 is a view equivalent to FIG. 6 showing the state in which the bolt and nut are tightened. [Figure 8] FIG. 10 is an enlarged longitudinal cross-sectional view showing a modified example of the rubber ring. [Figure 9] FIG. 10 is a partially enlarged cross-sectional view showing a watertight structure of a conventional pipe joint. DETAILED DESCRIPTION OF THE INVENTION

[0019] Next, the present invention will be described in more detail with reference to the accompanying drawings where appropriate. (Overview) 1, 6 and 7, the watertight structure 1 of a pipe fitting 10 according to the present invention generally comprises a socket 3 for another ductile cast iron pipe or the like inserted into a socket 2 for a ductile cast iron pipe, and a rubber ring 4 attached to the outer circumferential surface 3a of the socket 3 pressed against the socket 2 by a pressure ring 5 to effect a watertight seal. In the present invention, the watertight structure 1 further comprises an annular rubber packing 6 attached to the outer circumferential surface 3a of the socket 3 between the rubber ring 4 and the pressure ring 5.

[0020] (Socket 2) 4, the socket 2 includes a cylindrical first space 21 and a second space 22 whose inner diameter D6 increases from the first space 21 toward the opening 23. A flange 24 is provided on the outside of the opening 23, and a through-hole 25 is formed in the approximate center of the flange 24 to allow the T-head bolt 9a to pass through. In this embodiment, the socket 2 is, for example, a K-shaped socket for a ductile cast iron pipe.

[0021] (4 rubber rings) As shown in Figures 2 and 3, the rubber ring 4 comprises a cylindrical portion 41 whose tip portion 41a is inserted into the first space portion 21 of the receiving port 2, a tapered portion 42 whose outer diameter D3 expands from the other end portion 41b of the cylindrical portion 41 in the direction opposite to the tip portion 41a (the direction opposite to the insertion direction of the insertion port 3, rearward of the other end portion 41b), and a receiving portion 43 formed by the end face 41d of the other end portion 41b of the cylindrical portion 41 and the inner surface 42a of the tapered portion 42, and which receives the rubber gasket 6 described below.

[0022] The rubber ring 4 is made of a rubber material that is equal to or harder than the rubber packing 6 described below. In this embodiment, for example, the rubber hardness of the rubber ring 4 is 75° to 85°, and the rubber hardness of the rubber packing 6 is 70°.

[0023] Here, the inner diameter D1 of the cylindrical portion 41 is larger than the outer diameter D0 of the insertion port 3. Therefore, there is no need to use a lubricant, and as shown in Figure 6, for example, the insertion port 3 can be smoothly inserted in a temporary assembled state with the rubber ring 4 attached to the receiving port 2 in advance, which provides excellent workability. Furthermore, the rubber ring 4 can be easily removed from the receiving port 2 and the insertion port 3 when re-installing.

[0024] Furthermore, the outer peripheral surface of the tip 41a of the cylindrical portion 41 is flat, and does not have the rounded portion 4'a found in conventional rubber rings 4'. The thickness t of the tip 41a is equal to the height H of the protrusion 26 that forms the inner surface 21a of the first space 21. This allows the tip 41a to be inserted (attached) so that it fits along the first space 21, so that when pressed (joined) with the press ring 5, the insertion port 3 is not pulled further into the receiving port 3 than the intended joining position, improving workability.

[0025] Furthermore, the outer diameter D2 of the tip 41a of the cylindrical portion 41 is formed slightly larger than the inner diameter D5 of the first space portion 21, and the outer diameter D3 of the tapered portion 42 is formed slightly larger than the inner diameter D6 of the second space portion 22. Therefore, as shown in Figure 5, when attaching the rubber ring 4 to the socket 2, the cylindrical portion 41 and the tapered portion 42 must be reduced in diameter. The rubber repulsive force caused by this reduction temporarily fixes the rubber ring 4 to the socket 2. Note that "slightly larger" means, for example, that the outer diameters D2 and D3 of the rubber ring 4 are 1 to 3% larger than the inner diameter of the socket 2 (the inner diameters D5 and D6 of the first and second spaces 21 and 22).

[0026] The tapered portion 42 is formed so that its thickness T gradually decreases from the other end 41b toward the tapered tip portion 42x. The outer surface 42b of the tapered portion 42 is inclined at a predetermined outer inclination angle α relative to the cylindrical portion 41, and the inner surface 42a of the tapered portion 42 is inclined at a predetermined inner inclination angle β relative to the cylindrical portion 41. The inner inclination angle β is larger than the outer inclination angle α; in this embodiment, for example, the outer inclination angle α is 20.5° and the inner inclination angle β is 30°.

[0027] In the case of a K-shaped socket 2, the taper angle of the second space 22 is 20°. Therefore, it is conceivable to set the inner inclination angle β of the rubber ring 4 to approximately 20°, the same as the outer inclination angle α. However, in this case, the tapered portion 42 becomes thin to ensure the receiving portion 43, making it difficult to ensure the strength of the cylindrical portion 41 and to manufacture a rubber mold. Even if such a mold could be manufactured, rubber is difficult to restore its original shape, and the small angle makes the rubber packing prone to clogging at the corner tips, making it difficult to remove and unsuitable for re-installation. Furthermore, to facilitate the diameter reduction due to compressive deformation of the front convex rib 62a of the rubber packing 6 (described later), the inner inclination angle β must be larger than the outer inclination angle α, for example, 30°. This ensures the waterproofing of the rubber packing 6.

[0028] In addition, in this embodiment, the tapered tip 42x of the tapered portion 42 is provided with a locking portion 44 that locks onto the outer edge portion 2a of the receiving port 2 (outer surface 24a of the flange 24), and a bulging portion 45 that bulges inward (toward the center axis of the rubber ring 4) from the locking portion 44.

[0029] Moreover, the bulge 45 is tapered such that the inner diameter D4 of the bulge 45 narrows outward (toward the opening edge). As described above, the outer diameter D3 of the tapered portion 42 is slightly larger than the inner diameter D6 of the second space 22. Therefore, when the tapered portion 42 is fitted into the second space 22, the tapered portion 42 is reduced in diameter. As shown in FIG. 5 , the tapered portion 42 is also slightly reduced in diameter in the vicinity of the bulge 45 due to the reduction in diameter of the tapered portion 42. Therefore, after the rubber ring 4 is reduced in diameter (fitted into the socket 2), the inner surface 45a becomes flat (parallel to the pipe axis). This maintains contact between the outer edge 2a of the socket 2 and the contact surface 44a of the locking portion 44, ensuring stable fitting of the rubber ring 4 to the socket 2.

[0030] (Push Ring 5) As shown in Figures 1, 6, and 7, the pressure ring 5 generally has a ring-shaped main body 51 that surrounds the insertion port 3, a pressing part 52 that protrudes from the main body 51 in the pipe axial direction and presses the rubber gasket 6 described later, and a through hole 53 through which the T-head bolt 9a passes.

[0031] (Rubber packing 6) 6 and 7, an inner peripheral surface 61 of the rubber packing 6, which faces the outer surface 3a of the insertion port 3, is provided with a plurality of inner ridges 61a at appropriate intervals along the axial direction. Furthermore, a front surface 62 of the rubber packing 6, which faces the tapered portion 42a, is provided with a plurality of annular inner ridges 62a and annular inner recesses 62b, which are alternately arranged along the axial direction. A protrusion 63 is formed at the rear end of the rubber packing 6 to engage with the pressing portion 52 of the pressure ring 5. For example, a product such as that described in Japanese Patent Application Laid-Open No. 2003-232476 can be used as this rubber packing 6.

[0032] (Construction procedure) Here, the procedure for constructing the pipe joint will be described with reference to FIGS. As shown in FIG. 5 , first, the rubber ring 4 is attached to the socket 2. As described above, the outer diameter D2 of the tip 41a is slightly larger than the inner diameter D5 of the first space 21, and the outer diameter D3 of the tapered portion 42 is slightly larger than the inner diameter D6 of the second space 22. The inner surface 45a of the bulge 45 is tapered so that the inner diameter D4 of the bulge 45 narrows outward. As a result, when the tip 41a and the tapered portion 42 are reduced in diameter to attach the rubber ring 4 to the socket 2, the tip 41a and the tapered portion 42 come into close contact with the inner surfaces 21a and 22a of the first and second spaces 21 and 22, respectively, and the abutment surface 44a abuts against the outer edge 2a of the socket 2, temporarily securing the rubber ring 4 to the socket 2. This eliminates the need for the operator to hold down the rubber ring 4 attached to the socket 2, improving workability.

[0033] As shown in Figure 6, the rubber gasket 6 and pressure ring 5 are temporarily assembled to the socket 2 with the rubber ring 4 attached. The protruding portion 63 of the rubber gasket 6 is then engaged with the pressing portion 52 of the pressure ring 5, and a spacer 8 is sandwiched between the flange 24 of the socket 2 and the main body 51 of the pressure ring 5, and the T-head bolt 9a and nut 9b are tightened to create a temporary assembled state. This allows the rubber ring 4, pressure ring 5, and rubber gasket 6 to be temporarily fixed to the socket 2, and the rubber gasket 6 will not be pushed in during transportation to the construction site, etc. Furthermore, because the inner diameter D1 of the cylindrical portion 41 and the inner diameter D8 of the rubber gasket 6 are larger than the outer diameter of the socket 3, the socket 3 can be easily inserted in the temporary assembled state without using a lubricant, etc., resulting in extremely excellent workability.

[0034] As shown in Figure 7, the spigot 3 is inserted into the socket 2 in the pre-assembled state described above until it is positioned properly. The spacer 8 is then removed, and the T-head bolt 9a and nut 9b are tightened. This causes the pressing portion 52 to press the rubber gasket 6 toward the socket 2. However, because the rubber ring 4 is made of a harder rubber material than the rubber gasket 6, the rubber gasket 6 is primarily deformed. Therefore, due to the pressure of the pressing portion 52, the front ridge 62a is compressed and deformed by the inner surface 42a of the tapered portion 42, causing the entire rubber gasket 6 to move along the inner surface 42a toward the other end 41b, reducing its diameter. Further pressure causes the rubber gasket 6 to roll along the inner surface 42a, further reducing its diameter. The front surface 62 adheres closely to the inner surface 42a, improving watertightness. The inner ridge 61a of the inner peripheral surface 61 of the rubber gasket 6 also acts in a similar manner, compressing and deforming against the outer peripheral surface 3a of the spigot 3, causing the inner peripheral surface 61 to adhere closely to the outer peripheral surface 3a.

[0035] Furthermore, the pressure of the pressing portion 52 causes the rubber packing 6 to press against the end face 41d of the other end 41b of the rubber ring 4 and the inner surface 42a of the tapered portion 42. This pressure from the rubber packing 6 causes the tip end 41a of the rubber ring 4 to tightly contact the inner surface 21a of the first space 21, and the outer surface 42b of the tapered portion 42 to tightly contact the inner surface 22a of the second space 22. In this way, the rubber ring 4 and the rubber packing 4 hold the spigot 3 in the socket 2 and ensure watertightness of the pipe fitting 10.

[0036] Furthermore, when reinstalling, the T-head bolt 9a and nut 9b are loosened and the joints of the various components are disassembled. At this time, the rubber ring 4 is made of a harder rubber material than the rubber packing 6, and the thickness t of the tip 41a is equal to the height H of the protruding portion 26 of the socket 2. Therefore, the rubber ring 4 is not excessively deformed, and can be easily removed from the socket 2, allowing for reinstallation.

[0037] For example, for a pipe with a nominal diameter of 200, a tightening torque of about 20 Nm ensures watertightness of 2 MPa. Furthermore, with a tightening torque of 60 Nm, the pipe (insertion port 3) can be easily removed from the fitting body (receptacle port 2) by loosening the T-head bolt 9a and nut 9b and swinging the pipe fitting 10 by hand without using any tools. The removed pipe can then be inserted directly into the fitting body without resistance, allowing for re-installation. With a tightening torque of 100 Nm, a tool must be used to remove the pipe from the fitting body, but re-installation is possible in the same manner as above.

[0038] (Other embodiments) Finally, the possibility of other embodiments will be mentioned. Note that the same reference numerals are used to designate the same components as those in the above embodiment.

[0039] In the above embodiment, the inner surface 45a of the bulging portion 45 of the rubber ring 4 is tapered so that the inner diameter D4 of the bulging portion 45 narrows outward (toward the opening edge). However, for example, as shown in Figure 8(a), the inner surface 45a may be formed flat (parallel to the pipe axis). However, forming the inner surface 45a of the bulging portion 45 into a tapered shape as in the above embodiment makes it less likely that a gap will form between the rubber packing 6 and the rubber ring 4, making it easier to insert the insertion port 3 and preventing misalignment of the respective components.

[0040] Furthermore, in the above embodiment, no irregularities are provided on the outer surface 42b of the tapered portion 42 of the rubber ring 4. However, for example, as shown in Fig. 8(b), a plurality of annular protrusions 47 may be provided at appropriate intervals on the outer surface 42b. As a result, even if scratches occur on the tapered inner surface 22a of the second space portion 22, the deformation of the annular protrusions 47 can fill the gaps caused by the scratches, ensuring watertightness.

[0041] As shown in Fig. 1(c), it is also possible to omit the locking portion 44 and the bulging portion 45. However, the embodiment in which the locking portion 44 and the bulging portion 45 are provided is superior in terms of keeping the rubber packing 6 concentric with other members.

[0042] In the above embodiment, a K-shaped ductile cast iron pipe socket has been described as an example. Applicable K-shaped pipes include the K-shaped joint type specified in JIS G 5527 for ductile cast iron pipes, the K-shaped ductile cast iron pipe sockets specified in JWWA G 113 for ductile cast iron pipes for water supply and JWWA G 114 for ductile cast iron pipes for water supply (published by the Japan Water Works Association), and the K-shaped joint type specified in JSWAS G-1 for ductile cast iron pipes for sewerage (published by the Japan Sewage Works Association). However, the present invention is not limited to these K-shaped ductile cast iron pipes, and can also be applied to ductile cast iron pipes similar to the K-shaped ductile cast iron pipes. For example, the present invention can be applied to NS-shaped, S-shaped, US-shaped, UF-shaped, and U-shaped ductile cast iron pipes. The same is true for ductile cast iron pipes.

[0043] In the above embodiment, the rubber ring 4 is formed from a rubber material harder than the rubber packing 6, and an example has been given in which the rubber hardness of the rubber ring 4 is 75° to 85° and the rubber hardness of the rubber packing 6 is 70°. However, the rubber hardness is not limited to the above numerical values, and the rubber ring 4 may be formed from a rubber material with the same hardness as the rubber packing 6. For example, the rubber hardness of the rubber ring 4 may be 70° to 80°, and the rubber packing 6 may be formed from a rubber material with a rubber hardness of 70°. [Explanation of symbols]

[0044] 1: Watertight structure, 2: Receptacle, 2a: Outer edge, 3: Insertion port, 3a: Outer surface, 4, 4A, 4B, 4C: Rubber ring, 5: Press ring, 6: Rubber packing, 8: Spacer, 9a: T-head bolt, 9b: Nut, 10: Pipe joint, 21: First space, 21a: Inner surface, 22: Second space, 22a: Inner surface, 23: Opening, 24: Flange, 24a: Outer surface, 25: Through hole, 26: Protrusion, 40: Main body, 41: Cylindrical portion, 41a: Tip, 41b: Other end, 41c: Outer surface of other end, 41d: End surface, 42: Tapered portion, 42a: Inner surface, 42b: Outer surface, 42x: Tapered tip (end), 43: Receptacle, 4 4: locking portion, 44a: contact surface, 45: bulge portion, 45a: inner surface, 47: annular protrusion, 51: main body portion, 52: pressing portion, 53: through hole, 61: inner peripheral surface, 61a: inner convex rib, 62: front surface, 62a: front convex rib, 62b: front concave rib, 63: protrusion, D0: outer diameter of insertion port, D1: inner diameter of cylindrical portion, D2: outer diameter of cylindrical portion, D3: outer diameter of tapered portion, D4: inner diameter of bulge portion, D5: inner diameter of first space portion, D6: inner diameter of second space portion, D7: outer diameter of rubber packing, D8: inner diameter of rubber packing, H: height of protrusion, T: thickness of tapered portion, t: thickness of tip portion, α: inclination angle of outer surface, β: inclination angle of inner surface

Claims

1. A watertight structure for a pipe joint in which the spigot of another pipe is inserted into the spigot of a ductile cast iron pipe, and a rubber ring attached to the outer surface of the spigot is pressed against the spigot by a pressure ring to stop water flow. An annular rubber packing is further provided between the rubber ring and the press ring to be attached to the outer circumferential surface of the insertion port, The socket includes a cylindrical first space and a second space whose inner diameter increases from the first space toward an opening thereof, The rubber ring includes a cylindrical portion having a tip end inserted into the first space, a tapered portion whose outer diameter increases from the other end of the cylindrical portion in a direction opposite to the tip end, and a receiving portion that receives the rubber packing and is formed by the end surface of the other end of the cylindrical portion and the inner surface of the tapered portion, The inner diameter of the cylindrical portion is larger than the outer diameter of the insertion port, The tapered portion is formed so that its thickness gradually decreases from the other end toward the tapered tip, A waterproof structure for a pipe fitting in which the pressure ring presses the rubber gasket against the end face of the other end and the inner surface of the tapered portion, and the tip of the rubber ring is tightly attached to the inner surface of the first space portion, and the outer surface of the tapered portion is tightly attached to the inner surface of the second space portion.

2. 2. A water-stopping structure for a pipe fitting according to claim 1, wherein the outer diameter of the tip of the cylindrical portion is slightly larger than the inner diameter of the first space portion, and the outer diameter of the tapered portion is slightly larger than the inner diameter of the second space portion.

3. 3. A watertight structure for a pipe joint according to claim 2, wherein said tapered tip portion is provided with a locking portion that locks onto the outer edge of said socket and a bulging portion that bulges inward from said locking portion.

4. 4. The watertight structure for a pipe joint according to claim 3, wherein the inner surface of the bulge is tapered so that the inner diameter of the bulge narrows outward.

5. 2. The waterproof structure for a pipe joint according to claim 1, wherein the rubber ring is made of a rubber material that is equal to or harder than the rubber packing.

6. 6. A water-stopping structure for a pipe fitting as described in claim 5, wherein the rubber gasket has a front surface facing the inner surface of the tapered portion and an inner surface facing the outer surface of the pipe, and the front surface and the inner surface have a plurality of annular ridges provided at appropriate intervals.

7. 7. The watertight structure for a pipe joint according to claim 6, wherein an inclination angle of the inner surface of the tapered portion relative to the cylindrical portion is larger than an inclination angle of the outer surface of the tapered portion relative to the cylindrical portion.

8. 2. The watertight structure for a pipe joint according to claim 1, wherein a plurality of annular projections are provided at appropriate intervals on the outer surface of the tapered portion.

9. 9. The watertight structure of a pipe joint according to claim 1, wherein the socket of the ductile cast iron pipe is a K-type socket or a K-type socket similar to the K-type socket.

10. A rubber ring used in the watertight structure of a pipe joint in which the spigot of another pipe is inserted into the spigot of a ductile cast iron pipe, The socket includes a cylindrical first space and a second space whose inner diameter increases from the first space toward an opening thereof, The rubber ring includes a cylindrical portion having a tip end inserted into the first space, a tapered portion whose outer diameter increases from the other end of the cylindrical portion in a direction opposite to the tip end, and a receiving portion formed by the end surface of the other end of the cylindrical portion and the inner surface of the tapered portion, for receiving an annular rubber packing to be attached to the outer peripheral surface of the insertion opening; The inner diameter of the cylindrical portion is larger than the outer diameter of the insertion port, The tapered portion is a rubber ring formed so that its thickness gradually decreases from the other end toward the tip.

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