JPH0522978U - Inner surface corrosion protection fitting - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an inner corrosion-preventing pipe joint in which an adhesive layer is not peeled off and therefore a resin coating layer is not peeled off. [Structure] The inner diameter of the central portion 1b of the pipe joint body 1 is formed to be substantially equal to the inner diameter of the pipe 7 to be connected, and the female screw portion 3
Is formed on the inner side of the pipe joint body 1, and a resin coating layer 13 is formed on the inner peripheral surface including the depression 5 from the central portion of the pipe joint body 1 with an adhesive layer 11 interposed therebetween. A cylindrical portion 15 whose outer peripheral surface is in close contact with the inner peripheral surface of the pipe 7 to be connected is extended to form an annular space 17 between the cylindrical portion 15 and the female screw portion 3, and the cylindrical portion is formed. Multiple protrusions 15b on the outer periphery of 15
Is formed, and the seal member 19 is bonded onto the protrusion 15b.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an inner surface anticorrosion pipe joint, and more particularly to an inner surface anticorrosion pipe joint formed by injection molding a resin coating layer on an inner peripheral surface of a pipe joint body with an adhesive layer interposed therebetween.

[0002]

[Prior Art]

 Generally, a pipe joint in which a resin coating layer is formed on an inner peripheral surface of a pipe joint body via an adhesive layer (for example, Japanese Examined Patent Publication No. 2-51728), or an annular shape on the outer periphery of a tubular portion of the resin coating layer. A pipe joint in which a sealing member such as packing is fitted (for example, Japanese Utility Model Laid-Open No. 55-140888) is known.

[0003]

[Problems to be solved by the device]

 In this type, since the resin coating layer is formed on the inner peripheral surface of the pipe joint body by injection molding, the resin coating layer may become partially thicker or the resin coating layer may be thicker due to the structure of the pipe joint body. If there is a large fluctuation, the resin coating layer contracts during injection molding, causing peeling of the adhesive layer and peeling of the resin coating layer, or sink marks in the thick portion.

Further, in the case where the annular packing is simply fitted to the outer periphery of the tubular portion, resistance is not applied to the packing, and therefore, when the pipe is screwed into the pipe joint main body and connected, the end face of the pipe is moved. There is a problem that the packing is pressed and moves to the inner side of the tubular portion. When this moves to the back side, the packing and the pipe end face do not adhere to each other until the packing hits the back wall of the tubular portion, so that there is a problem that the pipe end face is exposed and the end face cannot be sufficiently corrosion-protected.

In order to solve this, it is necessary to use a cylindrical packing that is long in the axial direction, but this is uneconomical, and it must be devised so that the packing does not come off the cylindrical portion. There's a problem.

Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technique, to prevent peeling of the resin coating layer and partial shrinkage, and to ensure that the packing is securely attached to the end surface of the pipe. The object is to provide a pipe joint that is in close contact with the inner surface of the pipe joint and the pipe to surely prevent the inner surface from being corroded.

[0007]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention forms an inner diameter of a central portion of a pipe joint main body having an internal thread portion at an end portion to be substantially equal to an internal diameter of a pipe to be connected to the internal thread portion. , A recess is formed between the inner diameter of the central portion and the female threaded portion, the diameter of which is larger than the inner diameter of the female threaded portion, and an adhesive layer is formed from the central portion of the pipe joint body to the inner peripheral surface including the recessed portion. A resin coating layer is formed via the resin coating layer, and a cylindrical portion whose outer peripheral surface is in close contact with the inner peripheral surface of the pipe to be connected is extended at the end of the resin coating layer, and between the cylindrical portion and the female thread portion. In addition to forming an annular space, a plurality of projections extending in the circumferential direction are formed on at least the outer periphery of the cylindrical portion near the inlet, and a sealing member is bonded to the outer periphery of the projection. .

[0008]

[Action]

 According to the present invention, since the inner diameter of the central portion of the pipe joint body is almost the same as the inner diameter of the connecting pipe, the thickness of the resin coating layer injection-molded on the inner surface of the pipe joint body is almost the entire length of the pipe joint body. It becomes uniform. Therefore, when the resin is injection-molded, it is cooled uniformly and quickly, so that sink marks do not occur and the resin coating layer does not peel off. Further, both ends of the resin coating layer penetrate into the recess and are firmly adhered thereto, and further, between the central portion and both ends are firmly adhered to the inner peripheral surface of the main body through the adhesive layer. Therefore, the phenomenon that the resin coating layer is peeled from the both ends does not occur. Furthermore, a plurality of projections extending in the circumferential direction are formed on the outer circumference of the tubular portion, and a sealing member is bonded onto the projections, and the circumferential surface of the projections is inside the pipe. Since it closely adheres to the peripheral surface, when the pipe is screwed into the female thread and the end face of this pipe is moved to the inner side of the tubular part, the seal member is placed in contact with the seal member and the seal member is placed on the outer periphery of the protrusion. Since the seal is locked, the sealing and fixing of the seal member is reliable, the seal member is compressed and adheres to the pipe end face, and the seal member is sandwiched between the inner peripheral surface of the pipe and the outer peripheral surface of the tubular portion. Therefore, the inner surface of the pipe is reliably sealed. Therefore, the corrosion of the end surface of the pipe and the inner surface of the joint is surely performed. The protrusion may be formed in a ring shape or a spiral shape.

[0009]

【Example】

 Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a metal pipe joint body, and female screw portions 3 are screwed on the inner circumferences of both end portions 1 a 1, 1 a of the pipe joint body 1. The pipe joint body 1 is formed such that the inner diameter of the central portion 1b is approximately the same as the inner diameter of the pipe 7 to be connected, and thus the inner diameter of the central portion 1b is smaller than the inner diameters of both end portions 1a.

A recess 5 having a diameter larger than the inner circumference of the female thread 3 is formed at the terminal end 3 a of the female thread 3 connected to the inner circumference of the central portion 1 b of the pipe joint body 1. The portion 5 serves as a relief portion for the female screw portion 3a processed on both end portions 1a of the pipe joint body 1.

On the inner peripheral surface of the central portion 1 b of the pipe joint body 1, a resin coating layer 13 such as polybutene resin or crosslinked polyethylene resin is formed by injection molding with a hot melt adhesive layer 11 interposed therebetween. Both ends 13a of the resin coating layer 13 penetrate into the recess 5, and the resin coating layer 13 is adhered to the inner peripheral surface of the recess 5 via the hot melt adhesive layer 11. . The hot melt adhesive layer 11 is melted by the heat at the time of resin molding, and the resin coating layer 13 is firmly adhered to the joint body 1.

Further, at both ends of the resin coating layer 13, a tubular portion 15 having substantially the same thickness as the resin coating layer 13 is integrally extended, and the outer periphery of the tubular portion 15 and the female screw portion 3 An annular void 17 is formed between the inner surface of the hollow portion 5 and the end surface 15c of the tubular portion 15 between the inner surface of the hollow portion 5 and the inner periphery of the hollow portion 5. .

Explaining the tubular portion 15 in detail, as shown in FIG. 2, a plurality of projecting portions 15b are formed on the outer periphery of the tubular portion 15 near the entrance, and the plurality of projecting portions 15b are formed on the plurality of projecting portions 15b. A sealing member 19 made of a room temperature vulcanizing type rubber ring or the like is bonded. When connecting the pipe 7 to the pipe joint body 1, the inner circumference of the resin coating layer 7a on the inner surface of the pipe 7 comes into contact with the outer circumferences of the multiple projections 15b of the tubular portion 15. According to this, since the tubular portion 15 and the pipe 7 are in close contact with each other, the inner peripheral surface of the pipe joint body 1 is completely protected from the fluid.

The seal member 19 is adhered to the vicinity of the inlet of the tubular portion 15, and when the pipe 7 is connected to the female screw portion 3 of the pipe joint body 1, the protrusion 15 a slides on the seal member 19. Since resistance is applied, the sealing member 19 does not move easily even if the tip surface of the tube 7 moves to the inner side of the tubular portion 15, and only when the pushing force overcomes this sliding resistance. The seal member 19 moves to the inner side of the tubular portion 15.

Therefore, the seal member 19 is pushed after the end face of the pipe 7 is reliably brought into contact with the seal member 19, so that when the connection of the pipe 7 is completed, the end face of the pipe 7 is sealed by the seal member 19. Since the seal member 19 is sandwiched between the seal member 19 and the outer peripheral surface of the tubular portion 15, the sealability against internal water is significantly improved, and the pipe end surface is surely covered with the seal member 19. Corrosion protection of the pipe 7 and the pipe joint body 1 is performed.

Although the present invention has been described based on the embodiment, it is obvious that the present invention is not limited to this.

For example, the female threads 3a made of a resin coating layer may be formed so that the female threads 3 at both ends of the pipe joint body are continuous to the inner surface of the resin coating layer adhered in the recess. In this case, the protrusion 15b on the outer periphery of the cylindrical portion 15 may be formed as a male screw-like protrusion having the same pitch as the female screw 3a in consideration of the shape of the mold. According to this, it is possible to obtain the effect that the projection 15b for improving the sealing property can be formed at the same time when the female screw 3a is formed. Further, as the protrusion 15b, a male thread-like protrusion having the same pitch as that of the female screw portion 3 is formed in two to three threads so that the engagement with the seal member 19 is surely performed. May be improved. The protrusion 15b may be provided over the entire outer peripheral surface of the tubular portion 15.

[0019]

[Effect of the device]

 As is clear from the above description, according to the present invention, the thickness of the resin coating layer formed on the inner peripheral surface of the pipe joint body is uniform over almost the entire length thereof, so that the resin coating layer is No thick portion is formed in the layer, so that sink marks do not occur during so-called injection molding, and thus peeling of the resin coating layer is reliably prevented. Further, both ends of the resin coating layer penetrate into the recess, and both ends are firmly adhered to the inner peripheral surface of the recess through the adhesive layer, so that when the pipe is connected, Even if the tip contacts, the defect that the resin coating layer peels off is completely eliminated. Furthermore, since a plurality of protrusions are formed on the outer peripheral surface of the tubular portion and the seal member is adhered to the outer periphery of the protrusion, the seal member fixed near the inlet is compressed when the pipe is connected. Since the end surface of the pipe is covered with the seal member and the sealing member is sandwiched between the end face of the pipe and the outer surface of the tubular portion to seal, the pipe and the pipe joint body can be reliably protected from corrosion. Further, since the seal member is adhered to the outer circumference of the protrusion, there is no fear that the seal member will come off before connecting the pipe.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a pipe according to an embodiment of the present invention after connection with a pipe.

FIG. 2 is a longitudinal sectional view showing a state before connection with a pipe according to an embodiment of the present invention.

[Explanation of symbols]

 1 Pipe Joint Main Body 1a Both Ends 1b Central Part 3 Female Threaded Part 3a Resin Female Thread 5 Dimple 7 Inner Surface Resin Coated Steel Pipe 7a Inner Resin Coated Layer 11 Adhesive Layer 13 Resin Coated Layer 13a Both Ends of Resin Coated Layer 15 Cylindrical Part 15a Tip of tubular part 15b Plural projections 17 Void 19 Seal member

Claims (1)

[Scope of utility model registration request] 1. An inner diameter of a central portion of a pipe joint body having an internal thread portion on an inner periphery of an end is formed to be substantially equal to an internal diameter of a pipe to be connected to the internal thread portion, and the inner diameter of the central portion and A recessed portion having a diameter larger than the inner diameter of the female threaded portion is formed between the female threaded portion and a resin coating layer via an adhesive layer from the central portion of the pipe joint body to the inner peripheral surface including the depressed portion. A cylindrical portion whose outer peripheral surface is in close contact with the inner peripheral surface of the pipe to be connected is formed at the end of the resin coating layer, and the annular portion is formed between the cylindrical portion and the female screw portion. And forming a plurality of protrusions extending in the circumferential direction on the outer periphery of at least the inlet of the cylindrical portion, and bonding a seal member to the outer periphery of the plurality of protrusions. Inner corrosion protection pipe fitting.