JP2010281411A - Resin pipe joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin pipe joint capable of further surely preventing slipping-out of a resin pipe, even when the resin pipe cannot be held by fastening of a ring by an excessive tensile load, when enhancing pull-out strength more than conventional strength. <P>SOLUTION: This resin pipe joint has an in-core having a tapered outer surface part for diametrically expanding the pipe end of the resin pipe and driven into the pipe end, and a chuck ring for inserting the resin pipe and fastening and holding an insertion part of the resin pipe to and by the in-core by further contracting a diameter by threaded engagement to a body of a nut. The tapered outer surface part of the in-core is set at an inclination capable of diametrically expanding a distal end part of the resin pipe projecting from the chuck ring in a larger diameter than a diameter contracting time inner diameter of the chuck ring, and a tooth capable of biting in an inner peripheral surface of the distal end part to pull-out of the resin pipe, is arranged in a plurality in an annular shape, and a tooth capable of biting in an outer peripheral surface of the resin pipe, is also arranged in a plurality in an annular shape on an inner peripheral surface of the chuck ring. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a joint of a resin pipe represented by a polyethylene double-layer pipe for water supply, and relates to an improved structure that can more reliably prevent the resin pipe from coming out.

  The metal joint of the polyethylene double-layer pipe for waterworks is a ring as a main body part, a ring (chuck ring) as a retaining part attached to the outside of the resin pipe, and tightening (screwing) to the cylinder. A nut (cap nut) as a tightening part for reducing the diameter of the pipe and an in-core as a shaft core part for holding the pipe end of the resin pipe with the reduced diameter ring, and the resin pipe is inserted through the nut and the ring. The resin tube is tightened and fixed toward the incore by reducing the diameter of the ring by the procedure of driving the incore into the tube end and then tightening the nut into the trunk.

  In addition, according to the published standard (Non-Patent Document 1) regarding polyethylene pipe metal joints for waterworks of the Japan Waterworks Association, the incore has a tapered outer surface, and its large diameter side is subjected to a slip-out prevention treatment, and the resin pipe According to the type, it is classified into one type and two types. In a metal joint for type 1 pipe, as shown in Patent Document 1, when an external force in the drawing direction is applied to the end of the in-core, a flange is formed on the end of the in-core. Contacts the ring to prevent the resin tube from coming out.

  On the other hand, in the metal joint for two types of pipes, as shown in FIG. 5, the in-core 20 does not have a flange (buttock) at the end 21, but has several shallow grooves 23 on the outer surface 22 on the large diameter side. The groove 23 becomes a frictional resistance and prevents the resin pipe P from coming out.

JP 2009-79750 A

"Polyethylene pipe metal fittings for waterworks", Japan Waterworks Association Standard, Japan Waterworks Association, August 9, 2004, p. 2, p. 6-7

  By the way, the in-core is an independent member that is separate from the body and the ring, and when this is driven firmly into the resin tube, if an external force in the pulling direction is applied to the resin tube, it simply slides integrally with the resin tube. Therefore, it goes without saying that the incore alone does not prevent the resin tube from being pulled out, and most of the resin tube removal prevention function is realized by tightening the ring. However, conventional metal joints have a ring with a smooth inner surface, so the resin pipe slides out of the ring due to a relatively small tensile load, which is sufficient for earthquakes and crustal deformation. It was hard to say that it was possible to cope with.

  Therefore, it is conceivable to form biting teeth that are caught on the resin tube surface on the inner surface of the ring. In fact, the present applicant has already applied for a resin pipe joint in which an acute bite tooth 31 is formed on the inner surface 30 of the ring as shown in FIG. 6 (Japanese Patent Application No. 2007-334604). Although the pulling strength higher than that of the conventional metal joint was confirmed by adopting it, there were still problems to be solved.

  That is, since the polyethylene pipe for water supply, which is the object to be joined, has softness, it is possible to obtain high pulling strength by biting the above-mentioned biting teeth of the chuck ring on its surface, but on the other hand, excessive tensile load is applied. When this occurs, the plastic resin tube is stretched and the wall of the tube is thinned, and the biting depth of the biting teeth becomes shallow, or the surface of the resin tube is damaged by the biting teeth. To do. However, even if the holding force of the resin pipe by the ring is reduced by such an excessive tensile load, the resin pipe is not immediately pulled out from the joint. This is because the pipe end of the resin pipe is enlarged by the in-core to be larger than the reduced diameter inner diameter of the ring, thereby preventing the resin pipe from coming out of the ring.

  Thus, even after the resin tube cannot be held by tightening the ring, the resin tube can be held to a certain extent by preventing the end of the expanded pipe from being pulled out by the in-core. As a result, the tensile load is concentrated on the abutting portion between the ring and the end of the expanded pipe, and the phenomenon of trying to escape from the in-core occurs through the ring. In this respect, the previous application adopts the same in-core as the conventional type 2 metal joint for pipes shown in FIG. 5, and the groove formed on the outer peripheral surface exerts a knurling function to prevent the resin pipe from coming out. Although the groove is shallow, the inner core of the resin tube is not so strong and the incore has a tapered outer surface that tapers in the tensile direction (the direction of the resin tube coming out). When the pipe starts to come out of the in-core, the pawl does not work and there is a possibility that the resin pipe comes out of the joint at once.

  The present invention has been made in order to solve the above-mentioned problems, and the purpose of the present invention is to increase the pull-out strength compared to the conventional case, and the resin tube cannot be held by tightening the ring due to excessive tensile load. However, it is to provide a resin pipe joint that can more reliably prevent the resin pipe from coming out.

  In order to achieve the above-described object, in the present invention, an in-core having a tapered outer peripheral surface portion that expands the pipe end of the resin pipe and is driven into the pipe end, and the resin pipe are inserted and screwed to the barrel of the nut. And a chuck ring for tightening and holding the insertion portion of the resin tube to the in-core, and the tapered outer peripheral surface portion of the in-core has a tip portion of the resin tube protruding from the chuck ring. An inclination angle capable of expanding to a larger diameter than the inner diameter at the time of diameter was used, and a plurality of teeth that could bite into the inner peripheral surface of the tip portion with respect to the drawing of the resin tube was provided in an annular shape.

  The parts constituting the resin pipe joint of the present invention are the same as conventional polyethylene pipe metal joints for water supply, but the inclination angle of the tapered outer peripheral surface portion in the in-core is larger than that of the conventional one, and the inner peripheral surface has biting teeth. It differs from the conventional joint in that it is formed. That is, according to the present invention, the pipe end of the resin tube is expanded to a larger diameter than the inner diameter when the chuck ring is contracted by the in-core, so that the diameter-expanded pipe end (the tip portion of the resin pipe) is the chuck ring. To prevent the chuck ring from slipping out. In this state, since the in-core biting teeth bite into the inner peripheral surface of the end of the diameter-expanded pipe, the pulling strength of the resin pipe is higher than before. In particular, even if an excessive tensile load is applied to the resin pipe that causes the holding function of the resin pipe to be lowered or lost due to the tightening of the chuck ring, the ring contact structure outside the tip portion expanded by the in-core described above By the two tooth biting structures inside the tip portion, it is possible to prevent the resin tube from being pulled out by the tensile load.

  Further, by providing a plurality of teeth that can bite into the outer peripheral surface of the resin tube on the inner peripheral surface of the chuck ring, the pulling strength can be further increased.

  Furthermore, by making the tooth sawtooth wave shape in the direction that resists the pulling out of the resin tube, the edge becomes sharper with respect to the pulling out direction of the resin tube, and the tooth tends to bite in the opposite direction. There is little resistance to movement, and the in-core driving and inserting work into the chuck ring can be performed smoothly.

  Note that if the inclination angle of the tapered outer peripheral surface portion of the incore is less than 4 degrees, the diameter of the tube end cannot be effectively expanded. Since the force to slip through increases, it is preferable to set the angle within a range of 4 to 5 degrees.

  Furthermore, by making the inner diameter of the incore uniform over the entire area, the thickness of the tapered outer peripheral surface portion is increased, and the strength can be ensured even when teeth are formed by engraving the peripheral groove.

  According to the present invention, since the inclination angle of the tapered outer peripheral surface portion of the in-core is larger than that of the conventional one, and the biting teeth are provided on the outer peripheral surface, even when the holding capacity of the resin tube by the chuck ring is reduced, The diameter expansion structure of the tip portion protruding from the chuck ring and the tooth biting structure prevented the resin tube from coming off, and the final pulling strength of the resin tube could be increased. Furthermore, by providing biting teeth on the inner peripheral surface of the chuck ring, the initial pulling strength can be increased compared to the conventional case.

The upper half sectional view of the resin pipe joint which shows one embodiment of the present invention Same as above, in-core upper half section Same as above, enlarged sectional view showing in-core biting teeth Comparison table showing the results of the pull-out test of the prototype of the present invention and the conventional product Conventional metal fittings for polyethylene pipes for waterworks Resin pipe joint showing another prior art

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an upper half cross-sectional view of a resin pipe joint according to an embodiment of the present invention, in which 1 is an outer peripheral surface whose outer diameter is increased from the insertion tip (left side in the drawing) toward the rear end. It is a taper-shaped incore, and the pipe end is expanded and deformed by being press-fitted into the pipe end of the resin pipe P. More specifically, as shown in FIG. 2, an insertion taper portion 1a, a horizontal portion 1b, and a tapered outer peripheral surface portion 1c substantially the same as the inner diameter of the resin pipe P are formed from the tip end side. In this embodiment, the inclination angle θ of the tapered outer peripheral surface portion 1c is set to 5 degrees. The tapered outer peripheral surface portion 1c is provided with a plurality of biting teeth 1d. As shown in FIG. 3, the biting tooth 1d is provided by carving a right triangular triangular circumferential groove 1e having an apex angle α of 60 degrees, and has a cross-sectional saw facing in a direction to resist pulling out of the resin tube. It has a wave shape, and the right-angled edge portion 1f bites into the inner peripheral surface of the tube end. However, since the biting teeth 1d are oriented in the direction against the pulling out of the resin tube, the biting teeth 1d do not obstruct the driving of the incore 1 with respect to the tube end. Moreover, in this embodiment, since the inner diameter 1g of the incore 1 is uniform over the entire region and the thickness of the tapered outer peripheral surface portion 1c is ensured, the strength of the incore 1 is not reduced even by engraving the peripheral groove 1e.

  Next, 2 is a main body (cylinder) provided with a water passage hole 2a, and an outer sleeve 3 is integrally projected at one end (left side in the drawing) coaxially with the water passage hole 2a. is there. The outer sleeve 3 has a pipe end of the resin pipe P expanded in diameter by the in-core 1 and is inserted for a predetermined length together with the in-core 1, and the inner peripheral surface on the opening side thereof has a reverse taper shape, that is, an opening. A throttle port 3a is formed which is reduced in diameter from the end toward the back end. Further, a male screw 3b is formed on the outer peripheral surface of the outer sleeve 3 to which a cap nut described later can be screwed.

  4 is a chuck ring, and the outer diameter of the annular body through which the resin pipe P can be inserted (the drawing, the right side) is reduced to the same inclination angle as the throttle port 3a to form the outer peripheral surface taper portion 4a. With the maximum outer diameter portion 4b as a terminal, the rear end side outer diameter is reduced in the direction opposite to the outer peripheral surface taper portion 4a to form the rear end taper portion 4c. By these taper portions 4a and 4c, the chuck ring 4 has a substantially barrel-like appearance in which a part around the axis is enlarged. Further, a biting tooth 4d is projected from a part of the peripheral surface on the rear end side of the inner hole of the chuck ring 4. In the case of this embodiment, sawtooth-shaped biting teeth 4d having a cross section inclined against the drawing of the resin tube P are formed in duplicate.

  Reference numeral 5 denotes a cap nut that encloses the chuck ring 4 and is screwed into the male screw 3b of the outer sleeve 3, and has an inner collar 5b that penetrates an insertion hole 5a through which the resin pipe P can be inserted. Yes. Further, the inner peripheral surface 5c of the inner flange 5b is inclined from the female screw portion 5d toward the insertion hole 5a. The inclined inner peripheral surface 5c has a gentler inclination angle than the rear end taper portion 4c of the chuck ring 4 and can ride on the maximum outer diameter portion 4b of the chuck ring 4 as the cap nut 5 is tightened into the outer sleeve 3. .

  Next, the connection procedure of the resin pipe P by the resin pipe joint having the above-described configuration will be described. First, the resin pipe P is inserted in advance through the cap nut 5 and the chuck ring 4 in this order, and the incore 1 is hammered at the pipe end. Etc. and press fit. And if this pipe end is inserted in the outer sleeve 3 and the cap nut 5 is tightened, the connection is completed.

  According to the above connection procedure, by tightening the cap nut 5, the chuck ring 4 is axially moved on the resin pipe P by being pushed by the inner flange 5b, and the outer peripheral surface tapered portion 4a is the throttle port 3a of the outer sleeve 3. Fit in watertight. Then, as the insertion depth of the outer peripheral surface taper portion 4a increases, the chuck ring 4 starts to reduce the diameter while maintaining the water tightness with the throttle port 3a, and the front end side of the inner hole is connected to the expanded outer peripheral surface of the pipe end. The sealing portion is formed on the contact surface, and the biting teeth 4d on the rear end side bite into the outer peripheral surface of the tube end to hold the resin tube P so that it can be prevented from coming off.

  Further, when the cap nut 5 is tightened, the inner peripheral surface 5c of the inner flange 5b rides on the maximum outer diameter portion 4b of the chuck ring 4 and presses the maximum outer diameter portion 4b in the radial direction, thereby the chuck ring 4 The rear end side is reduced in diameter. Accordingly, the diameter of the chuck ring 4 is reduced uniformly over the entire length, and the biting teeth 4d can be deeply bitten into the outer peripheral surface of the pipe end. In this operation, the chuck ring 4 is more easily and reliably reduced in diameter by the slit 4e, so that the tightening torque of the cap nut 5 can be reduced.

  In this way, the chuck ring 4 tightens the resin pipe P toward the in-core 1 and the biting teeth 4d bite into the outer peripheral surface of the resin pipe, whereby the initial pulling strength is exhibited. Although it is superior to the conventional joint that employs a ring that does not have the teeth 4d, in the present invention, even when an excessive tensile load exceeding the initial pulling strength is applied to the resin pipe P, the following is performed. The final pullout strength is obtained to prevent the resin tube from being pulled out. That is, the tip portion P1 protruding from the chuck ring 4 is expanded by the in-core 1 to have a larger diameter than the inner diameter when the chuck ring 4 is contracted, so that this portion is caught by the tip of the chuck ring 4 and from the chuck ring 4 Omission is prevented. In addition, the biting teeth 1d of the in-core 1 bite into the inner peripheral surface of the tip portion P1 as the resin pipe P is pulled out, and this is inhibited, so that the pull-out from the in-core 1 is also prevented. Therefore, in the present invention, a large pulling strength is finally exhibited by both of these pull-out preventing structures.

  A pull-out test was conducted on a prototype of a joint applied to a polyethylene double-layer pipe for water supply having a nominal diameter of 50, and the final pull-out strength was examined. This prototype has a circumferential groove with an in-core 1 having a total length of 45 mm, an inner diameter of the front end of 41 mm, an outer diameter of 43 mm, an outer diameter of the rear end of 49 mm, a depth of 1.2 mm and an apex angle of 60 degrees. Three 1e are provided. The pull-out test was based on that described in Non-Patent Document 1.

  FIG. 4 is a comparison table showing the results of the pull-out test for the conventional product and the three prototypes (Nos. 1 to 3) of the present invention. The conventional product is 12.35 kN, and the pipe completely comes out of the joint. In contrast, in the present invention, in any of the prototypes, the pipe did not completely come out of the joint with a tensile load exceeding this. As shown in this result, the present invention has a higher pulling strength than the conventional resin pipe joint. Moreover, in the present invention, the higher the yield of the resin tube before the resin tube comes out, the higher the drawing strength.

  In the above-described embodiment, the reverse taper-shaped rear end taper portion 4c is provided on the rear end side of the chuck ring 4. However, this may be omitted, and a flare tube composed of only the outer peripheral surface taper portion 4a on the front end side may be used. Good. The material is preferably a synthetic resin such as a polyacetal resin, but may be a metal or the like.

1 In-core 2 Body (torso)
4 Chuck ring 5 Cap nut

Claims (5)

An in-core having a tapered outer surface portion that expands the pipe end of the resin pipe and is driven into the pipe end, the resin pipe is inserted, and the diameter of the resin pipe is reduced by screwing with a nut body. And a tapered outer surface portion of the in-core can expand the tip portion of the resin tube protruding from the chuck ring to a larger diameter than the inner diameter when the chuck ring is contracted. A resin pipe joint having an inclined angle and a plurality of annular teeth that can bite into the inner peripheral surface of the tip portion with respect to the drawing of the resin pipe. The resin pipe joint according to claim 1, wherein a plurality of teeth that can bite into the outer peripheral surface of the resin pipe are provided in an annular shape on the inner peripheral surface of the chuck ring. The resin pipe joint according to claim 1 or 2, wherein the annular tooth has a saw-tooth shape with a cross section oriented in a direction against the pulling out of the resin pipe. The resin pipe joint according to claim 1, 2, or 3, wherein the inclination angle of the tapered outer surface portion of the in-core is 4 to 5 degrees. The resin pipe joint according to any one of claims 1 to 4, wherein the inner diameter of the in-core is uniform over the entire area.

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