JP3710355B2 - Pipe end anti-corrosion structure for pipe joints - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tube end anticorrosion core of the insertion port in a pipe joint with an expansion / contraction function in which the other insertion port is inserted into one tube receiving port.
[0002]
[Prior art]
Conventionally, when a ductile cast iron pipe is buried in the ground to form a pipe line, the pipe line is subjected to anticorrosion by painting or lining over the entire pipe, and as shown in FIG. In general, the insertion port 2a of the succeeding tube 2 is inserted into 1a as shown by a chain line from the solid line and joined. In the figure, 5 is a lining layer, and 7 is a packing.
[0003]
The laying of the pipe line is not always limited only by joining with the fixed size pipes 1 and 2, and sometimes the pipe 2 must be cut and joined so as to have a predetermined length at the construction site. When the tube 2 is cut in this way, the coating is peeled off from the tube end surface serving as a cut surface, and the anticorrosion function is impaired, leading to generation of red water and the like. Therefore, anticorrosion is performed by re-applying the anticorrosive paint to the end face after the cut tube.
[0004]
Recently, even when an unsteady external force hits a pipeline directly due to an earthquake or the like, the pipe joint can be expanded and contracted, and the earthquake resistance that absorbs and relaxes the external force has been strongly demanded. The number of functions has increased. FIG. 17 shows a typical NS-type joint. A groove 3a is formed on the entire inner surface of the receiving port 1a of one pipe 1, and a lock ring 3 is fitted into the groove 3a, and the other pipe 2 is inserted. The outer surface of the end of the mouth 2a is formed into a tapered shape 2b having a downward slope toward the tip, and a groove 4a is formed in the entire rear periphery of the tapered surface 2b, and the slot 4a is engaged with the lock ring 3 The ring 4 is fitted, and the insertion port 2 a of the other tube 2 is inserted into the receiving port 1 a of the one tube 1 and the insertion ring 4 is inserted over the lock ring 3.
[0005]
In this pipe joint, the insertion port 2a can be moved from the position where the tip of the insertion port 2a hits the inner wall 1b of the receiving port 1a to the position where the insertion port ring 4 contacts the lock ring 3, and the joint is joined to the earthquake. When a large pulling force is applied due to, for example, the insertion ring 4 and the lock ring 3 are engaged with each other, detachment is prevented.
[0006]
In this NS type joint, when the pipe 2 is cut and laid so as to have a predetermined length, the tapered surface 2b and the cut ring insertion ring 4 are fitted into the outer peripheral surface of the pipe end after the cut pipe. The fitting groove 4a is formed separately. Since the anticorrosion paint is also peeled off from the groove 4a, the pipe end surface, and the tapered surface 2b, the anticorrosion paint is applied again to prevent corrosion.
[0007]
However, when anticorrosion paint is applied to the end face after the cut tube and corrosion prevention is performed again, it takes time to dry in cold weather, and it is difficult to apply in places where running water does not stop completely, such as switching work. There is a problem that it is difficult to work. Further, as a feature of the NS type joint used as an earthquake-resistant joint, when inserting the insertion port 2a into the receiving port 1a as shown by a chain line from FIG. 17, the insertion port ring 4 is inserted while expanding the lock ring 3. For this reason, there is a problem that due to the contact with the lock ring 3 at the time of insertion, the repainted anticorrosion paint is peeled off and a sufficient anticorrosion effect cannot be obtained.
[0008]
For this reason, a thin anticorrosion ring (core) made of stainless steel, synthetic resin, or the like is applied to the end surface of the cut tube as a method other than applying the anticorrosion paint again to the end surface after the cut tube to prevent the tube end Adhering with a system adhesive (Japanese Utility Model Laid-Open No. 7-22198) or the like, or attaching an anticorrosion cap (core) 6 formed of an elastic body such as rubber as shown in FIG. No. 253189, etc.), corrosion prevention is performed on the part where the anticorrosion paint is peeled off. In the figure, 8 is a ring for fixing the anticorrosion cap 6, which is made of an elastic material such as stainless steel that is split in the circumferential direction (see FIG. 3), and is fitted in the groove 9 around the inner surface of the anticorrosion cap 6. The anticorrosion cap 6 is inserted and fixed to the tube end of the opening 2a by the expansion force.
[0009]
[Problems to be solved by the invention]
In the pipe end anticorrosion structure using the anticorrosion core 6, the outer peripheral edge of the anticorrosion core 6 reaches the outer surface of the insertion ring 4. For this reason, when the insertion ring 4 when inserting the insertion opening 2a into the receiving opening 1a inserts and extends over the lock ring 3, the anticorrosion core 6 peels off or breaks due to the contact between both of them. There is a fear. In particular, when the lock ring 3 is expanded, if the anticorrosion core 6 comes into contact with the notch provided in the vicinity of the split part of the split ring 3 as it is inserted, it is damaged due to friction or the like, resulting in complete anticorrosion. The effect may not be satisfied.
[0010]
This invention makes it a subject to eliminate peeling and damage by contact friction etc. with the said lock ring 3 grade | etc., Of an anticorrosion core in view of the said situation.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a tube end anticorrosion structure with an anticorrosion core of an insertion opening fitted with the above insertion opening ring, and the outer end edge of the anticorrosion core is interposed between the insertion opening ring and the groove thereof. I decided to fix it. In this way, the anticorrosion core is difficult to peel off because its outer edge is inserted into the mouth ring and the inner edge is fixed to the fixing ring. In addition, in pipe joints where the insertion ring pushes over the lock ring and gets over it, the insertion ring is in direct contact with the lock ring without interposing the anticorrosion core. And damage is prevented. At this time, even if the anticorrosion core comes into contact with the lock ring, the inner and outer edges thereof are fixed, so that they are not easily peeled off.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
As an embodiment of the present invention, the insertion port of the other tube is inserted into the receiving port of one tube, and the outer surface of the insertion port end of the other tube is formed in a tapered shape with a downward slope toward the tip. In addition, in a pipe joint in which a groove is formed in the entire rear periphery of the tapered surface, and an insertion port ring is fitted in the groove, a taper surface and an insertion port end surface are formed from the insertion port ring groove to the entire periphery of the insertion port end. The anticorrosion core that passes through the inner surface of the anticorrosion core is inserted into the insertion ring and the groove, and the inner end edge of the anticorrosion core is fixed to the entire circumference. The structure fixed by can be adopted.
[0013]
In this configuration, it is preferable that a wear-resistant layer is formed on a portion where the outer surface of the anticorrosion core is easily worn. In this way, even if the anticorrosion core rubs against a notch such as a lock ring, it will not be worn and will not be damaged. The wear-resistant layer is formed by various means such as application, application, and integral molding of wear-resistant materials. More specifically, the anticorrosion core body is made of an elastic body such as ethylene propylene rubber, and the wear resistant layer is made of ultrahigh molecular weight polyethylene or the like.
[0014]
The ethylene propylene rubber (EPR) and the ultra high molecular weight polyethylene have the same chemical constitution, and the EPR has a vulcanization (molding) temperature of 150 ° C., for example, ultra high molecular weight such as technol (Otsuka Techno Co., Ltd .: trade name). Since the melting point of polyethylene is higher than 136 ° C., during the vulcanization of EPR, the ultrahigh molecular weight polyethylene is completely melted and reliably welded (adhered) to the ethylene molecules and propylene molecules of EPR. For this reason, an anticorrosion core having a wear-resistant layer made of ultrahigh molecular weight polyethylene is formed by, for example, placing an ultrahigh molecular weight polyethylene film in a mold and placing unvulcanized ethylene propylene rubber in the mold, and integrally vulcanizing and molding. .
[0015]
In the case of rubber, since it is generally a black surface having the same color as a metal tube or cast iron tube, it is difficult to determine whether or not the rubber anticorrosive core is attached to the insertion port. For this reason, at least one of the rubber (corrosion-proof core) or wear-resistant layer (ultra-high molecular weight polyethylene) is colored in a color different from that of metal pipes or cast iron pipes. Thus, it is preferable to prevent forgetting to attach the anticorrosion core during joint joining. When the wear resistant layer is not formed, the anticorrosion core is colored.
[0016]
Furthermore, when a groove for the insertion port ring is also newly formed, it is preferable to cover the exposed surface with a seal to prevent corrosion.
[0017]
【Example】
FIGS. 1 to 4 show an embodiment. This embodiment also relates to the NS type pipe joint shown in FIG. 17, and the cut-out insertion port 2a has a tapered surface 2b having a downward slope toward the tip. At the same time, a groove 4a is formed on the entire rearward circumference of the tapered surface 2b, and the split insertion ring 4 is fitted into the groove 4a. The EPR anticorrosion core 10 is fitted into the insertion opening 2 a having this configuration, and the outer end edge 10 a of the anticorrosion core 10 extends rearward and enters the lower surface of the insertion opening ring 4. 2a is fixed to the outer surface. The entering length of the end edge 10a is arbitrary. Moreover, the inner edge 10b of the anticorrosion core 10 also extends rearward and is fixed by a fixing ring 8 having a single split opening shown in FIG. In the figure, the same reference numerals as described above denote the same items.
[0018]
In this embodiment, as shown in FIG. 4a, after the anticorrosion core 10 is fitted and fixed by the fixing ring 8, the insertion ring 4 is fitted as shown in FIG. 4b. In this state, as shown in FIG. 17, it is inserted into the receptacle 1a. The cut surface, that is, the cut end surface 2c, the tapered surface 2b, and the groove 4a are preferably coated with anticorrosive paint, and applied to at least the groove 4a.
[0019]
In the embodiment shown in FIG. 5, the outer edge 10a is extended to the groove 4a to form the seal portion 13 of the groove 4a. At this time, as shown in FIGS. 6A and 6B, the seal portion 13 can be different from the anticorrosion core 10. The seal portion 13 may be the same as the anticorrosion core 10, but other elastic bodies, self-bonding tape, or the like can be adopted.
[0020]
In the embodiment shown in FIG. 7, the wear resistance of the outer surface of the anticorrosive core 10 is improved, and the ultrahigh molecular weight (1 million or more) polyethylene film 11 is fused around the entire core 10 or partially. A wear layer is formed to prevent EPR damage. At this time, when the insertion port 2a is inserted into the receiving port 1a, the lock ring 3 is inserted while the cutting tube insertion port ring 4 is expanded, so that the core is formed by a notch provided near the split portion of the lock ring 3. Ten tapered surfaces 10b are damaged. Moreover, since the connecting piece is attached to the split part of the insertion port ring 4, slight irregularities are formed, and the core 10 is damaged at the time of insertion by contact with the lock ring 3 due to the irregularities. For this reason, the partial wear-resistant layer 11 is a portion that may be damaged.
[0021]
The anticorrosion core 10 formed by fusing the ultrahigh molecular weight polyethylene film 11 to EPR has the same chemical structure as the ultrahigh molecular weight polyethylene and EPR. It is fused and formed integrally. This is because the vulcanization molding temperature of EPR is 150 ° C. and higher than the melting point of ultra high molecular weight polyethylene, so that the melted ultra high molecular weight polyethylene is bonded to the EPR ethylene molecules and propylene molecules to be firmly integrated. The ultra high molecular weight polyethylene film used is excellent in low friction and wear resistance, and the EPR 12 constituting the core 10 has a hardness of JIS K 6253. It is desirable that _HA is about 40 to 90 in terms of hardness according to the durometer hardness test specified in 1.
[0022]
FIG. 8 shows a mold (lower mold) 20 used for molding the anticorrosion core 10, and main parts of the molding process using the mold 20 are shown in FIGS. 9 (a) to 9 (c). First, as shown in FIG. 3A, a bend is placed on an ultra-high molecular weight polyethylene film 11 colored other than black, for example, yellow, and set in a cavity 21 that forms the outer surface shape of the core 10 of the mold 20. As shown in FIG. 4B, the unvulcanized EPR 12 is set in the cavity 21 of the mold 20 and the mold surface pressure is about 80 kgf / cm ^{2 by} the press 22 having a hot plate temperature of 150 degrees. Vulcanization molding is performed at molding pressure for about 15 minutes, and the ultrahigh molecular weight polyethylene film 11 and the EPR 12 are heat-sealed, and as shown in FIG. FIG. 7: integrally molded so that t) is 0.3 to 0.5 mm.
[0023]
Here, the bent shape and dimensions of the ultrahigh molecular weight polyethylene film 11 can be set in any way by the anticorrosion core 10 to be molded, and in the drawing, it is a mold manufactured for the NS type joint insertion port 2a. It goes without saying that any shape of the insertion opening 2a of another joint can be integrally vulcanized by changing the mold 20 (cavity 21) to a shape corresponding to the shape. Also, the ultra high molecular weight polyethylene film 11 is fixed to the press 22 side, the ultra high molecular weight polyethylene film 11 is heat-sealed to the unvulcanized EPR 12, and the core 10 inner surface side is also lined with the ultra high molecular weight polyethylene film 11. A way to do this is also conceivable. Furthermore, the outer circumferential surface tube axial length and the outer peripheral portion thickness of the molded tube end anticorrosion core 10 can be arbitrarily set within a range that does not inhibit the bending and expansion / contraction allowed for the joint.
[0024]
The thickness of the ultrahigh molecular weight polyethylene film 11 is preferably 0.05 mm to 0.4 mm. If the film 11 is too thin, the film 11 is thermally deformed when it is set on the mold 20, so that the bend cannot be held and cannot be fused at a predetermined location. On the other hand, if it is too thin, the original purpose of not damaging the EPR 12 due to the formation of a hole at the time of fusion cannot be achieved. On the other hand, when a too thick one is used, the shape of the thin portion is greatly deformed after cooling due to the difference in shrinkage between the rubber 12 and the ultrahigh molecular weight polyethylene 11. Moreover, if it finishes too thickly, the problem that the convex part of the core 10 and a joint inner surface will contact strongly and cannot join will generate | occur | produce.
[0025]
In this case, “deforms greatly” means that if the film 11 is too thick, it may be covered with the film 11 even if it does not need to be fused when pressed, This includes that the intrusion cannot be completely prevented, and that if the film 11 is too thick, there is a possibility that the tube end anticorrosion core 10 is made of only the ultrahigh molecular weight polyethylene film 11 instead of being integrated with the rubber 12. However, in this case, if the rubber part is reduced, there is a problem that the inner and outer diameter tolerances of the connecting pipes 1 and 2 cannot be absorbed.
[0026]
By the above-described method, the ultrahigh molecular weight polyethylene film 11 is partially fused to the EPR 12 to form the anticorrosion core 10 in which the EPR portion remains (not fused), so that the EPR 12 has an allowable inner and outer diameter of the pipe. Smoothly absorb the difference. Incidentally, when the film 11 is welded to the entire surface of the core 10, that is, when the EPR 12 is wrapped with the film 11, the EPR 12 therein is also hardly deformed, and the absorption effect is deteriorated. On the other hand, the tensile stress of the portion lined with the ultrahigh molecular weight polyethylene film 11 is about twice that of the EPR 12 alone, the tear strength is about 1.5 times, and physical properties such as sliding (wear) are improved.
[0027]
Here, simply covering the ultrahigh molecular weight polyethylene film 11 and the EPR 12 with the inner and outer surfaces of the insertion port 2a cannot make the two tight, and cannot prevent water from entering between them. By being molded, the boundary between the EPR 12 and the ultrahigh molecular weight polyethylene film 11 is also formed on a surface without a seam (groove, step), and can be tight and can prevent water from entering.
[0028]
10 to 16 show other embodiments, and the embodiment of FIG. 10 is obtained by extending the ultrahigh molecular weight polyethylene film 11 to the extended portion (outer edge) 10a (seal portion 13) of the EPR 12. 11 and 12, the extension portion 10a of the EPR 12 is stopped, and the extension portion is formed only by the ultrahigh molecular weight polyethylene film 11. FIG. In FIGS. 13 and 14, contrary to FIGS. 11 and 12, the ultrahigh molecular weight polyethylene film 11 is only the exposed portion of the core 10. FIG. 15A shows an ultra-high molecular weight polyethylene film having only a tapered surface 10c, and FIG. 15B shows a case where the anticorrosion core 10 is fused to the inner surface, the end surface, and the entire outer surface of the tapered surface 10c. . In the embodiment shown in FIGS. 16A and 16B, the fixing ring 8 is positioned by simply forming a step 9 a instead of the groove 9. This embodiment can also be adopted in those shown in FIGS. 5 to 7 and FIGS. In addition, in each Example, the thickness (outer diameter) of the outer peripheral part of the insertion port 2a can be arbitrarily set by changing the formation thickness of the EPR 12 and the film 11.
[0029]
In addition, although the Example was a case of NS type joint, of course, this invention can be employ | adopted also in the other pipe joint which has the insertion port ring 4. FIG.
[0030]
【The invention's effect】
Since this invention was carried out as described above, peeling and damage of the anticorrosion core can be effectively prevented. For this reason, the anticorrosion function can be maintained over a long period of time.
[Brief description of the drawings]
1 is a perspective view of an essential part of one embodiment. FIG. 2A is a cross-sectional view taken along line AA in FIG. 1, and FIG. 1B is an enlarged view of an essential part of FIG. Fig. 4 is a perspective view of a fixing ring. Fig. 4 is a view showing the operation of the same embodiment. Fig. 5 is a cross-sectional view of an essential part of another embodiment. FIG. 8 is a sectional view of the main part of another embodiment, FIG. 8B is an enlarged view of the main part of FIG. 8A and FIG. (A) is a cross-sectional view of the main part of another embodiment, (b) is an enlarged view of the main part of (a). FIG. 11 (a) is a cross-sectional view of the main part of another embodiment, (b) is ( FIG. 12A is a cross-sectional view of a main part of another embodiment. FIG. 13B is an enlarged view of a main part of FIG. 13A. FIG. Cross-sectional view of main parts, (b) is an enlarged view of main parts of (a). [FIG. 14] (a) is a cross-sectional view of main parts of another embodiment, (b) FIG. 15 is a cross-sectional view of main parts of other examples. FIG. 16 is a cross-sectional view of main parts of other examples. FIG. 17 is a partial cross-sectional view of an example of a pipe joint structure. 18] Cross section of the main part of the conventional example [Explanation of symbols]
1, 2 Tube 1a Receiving port 2a Inserting port 2b Inserting port tapered surface 3 Lock ring 3a Locking ring groove 4 Cutting tube insertion ring 4a Inserting ring groove 5 Lining 6, 10 Corrosion-proof core 8 Fixing ring 10a Core outer edge 10b Core inner edge 10c Core taper surface 11 Wear resistant layer (ultra high molecular weight polyethylene film)
12 EPR
13 Sealing part

Claims (2)

The insertion port 2a of the other tube 2 is inserted into the receiving port 1a of the one tube 1, and the outer surface of the insertion port end of the other tube 2 is formed in a tapered shape with a downward slope toward the tip. In the pipe joint in which the groove 4a is formed in the entire rear periphery of the tapered surface 2b and the insertion ring 4 is fitted in the groove 4a,
The anticorrosion core 10 extending from the insertion opening ring groove 4a to the inner surface through the insertion opening end face is fitted to the entire circumference of the insertion opening end, and the outer edge of the anticorrosion core 10 is the lower surface of the insertion opening ring 4 The insertion ring 4 is inserted from the tip of the insertion ring 4 and is interposed between the insertion ring 4 and the outer surface of the insertion opening 2a and fixed by the diameter reducing force of the insertion opening ring 4, and the inner edge of the anticorrosion core 10 is all A pipe end anticorrosion structure in a pipe joint, wherein the pipe end is fixed by a fixing ring 8 over the circumference.   2. The pipe according to claim 1, wherein the main body of the anticorrosion core 10 is made of ethylene propylene rubber 12, and a wear resistant layer 11 made of ultrahigh molecular weight polyethylene is formed on a portion of the outer surface of the core which is easily worn. Pipe end anticorrosion structure for joints.

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