JPH0926066A - Pipe joint - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a pipe joint in which red water containing rust does not occur even when a high-temperature liquid flows. [Structure] A joint body 2 in which a female thread 21 is formed on the inner peripheral surface of a metal tubular body, and a tubular tubular anticorrosion core made of resin that is watertightly adhered to a resin layer 42 on the inner wall of a connecting pipe 4 connected to this joint body 2. Three
In the anticorrosion core 3 of the pipe joint 1 made of, the tip side portion 34 is formed to be thicker than the back side portion 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal pipe joint having a resin anticorrosion core.

[0002]

2. Description of the Related Art As a conventional pipe joint, for example, there is a pipe joint proposed by the present applicant in Japanese Patent Application No. 5-227906. As shown in FIG. 3, the pipe joint 9 is composed of a cast iron joint body 6 and a resin anticorrosion core 7 formed inside thereof, and four ribs are provided on the outer peripheral surface of the seal portion 71 of the anticorrosion core 7. 76 ... 76 are formed. When the male screw 81 of the anticorrosion pipe 8 is screwed into the female screw 61 of the joint body 6 and attached, the resin layer 82 covering the inner circumference of the anticorrosion pipe 8
However, the seal 71 is in close contact with the outer peripheral surface thereof. Further, four ribs 76 provided on the outer periphery of the seal portion 71 increase the water tightness between the seal portion 71 and the resin layer 82 of the anticorrosion pipe 8.

[0003]

However, when the pipe joint 9 and the anticorrosion pipe 8 are connected to each other for use in hot water supply equipment and hot water is poured into the hot water supply facility, the sealing portion 71 of the anticorrosion core 7 and the resin of the anticorrosion pipe 8 are connected. High-temperature hot water may ooze out from the gap between the layer 82 and the joint body 6 and the steel pipe portion 83 of the anticorrosion pipe 8 to cause rust, which may be carried along with water and come out as red water. This is due to the following reasons. That is, when the male screw 81 of the anticorrosion pipe 8 is screwed into the female screw 61 of the joint body 6 to be attached, the resin layer 82 on the inner circumference of the anticorrosion pipe 8 reduces the diameter of the seal portion 71 of the anticorrosion core 7 inward, but as a reaction thereof, A stress (restoring force) that spreads outward is generated in the seal portion 71. When the water temperature is low, this stress increases the adhesive force, but when the water temperature is high, the resin that forms the anticorrosion core becomes slightly softer and this stress becomes weaker. As shown in the partially enlarged view of FIG. In addition, the tip portion 74 of the seal portion 71 may be deformed inward. This is because the tip portion 74 itself may be reduced in diameter due to high heat, but the base end portion 73 to which a large tightening force is applied when screwing the anticorrosion pipe 8 has an action of reducing the diameter of the tip portion 74. Is. Therefore, the degree of this deformation is usually larger in the tip end portion 74 than in the base end portion 73.

In this way, the sealing portion 71 and the anticorrosion pipe 8
The degree of adhesion of the resin layer 82 is weakened, and hot water oozes out from there, causing rust to occur in the cast iron joint body 6 and the steel pipe portion of the anticorrosion pipe 8. Once this happens, the seal portion 71 remains deformed, and even when cold water is flown thereafter, the water oozes out from the seal portion 71 and rust spreads,
Red water often comes out. If this happens, there is no other repair method than replacement.

The present invention has been proposed in view of the above circumstances, and an object thereof is to provide a pipe joint in which there is no fear that red water will come out even when a high-temperature liquid flows.

[0006]

DISCLOSURE OF THE INVENTION A pipe joint according to the present invention comprises a joint body having a female cylindrical inner peripheral surface formed with an internal thread, and a resin body which is watertightly adhered to an inner wall surface of a coupling pipe connected to the joint body. A pipe joint comprising a tubular anticorrosion core,
The anticorrosion core is formed such that the thickness of the tip side portion is thicker than the thickness of the back side portion.

Incidentally, depending on the material of the connecting pipe to be connected,
Since it may not be necessary to prevent corrosion, the configuration of the present invention need only be provided on the side where it is needed. In the above-mentioned configuration, the pipe joint includes not only a straight pipe joint (socket) but also a pipe that can connect the pipes, that is, an elbow, cheese, a valve, and the like. Further, in the above structure, the material of the anticorrosion core is, for example, vinyl chloride resin, polyethylene resin, polybutene resin or the like, from the viewpoint of easiness of processing and economy. Furthermore, the inner and outer surfaces of the joint body may be resin-coated.

[0008]

[Operation] With two pipes connected to both ends of the pipe joint,
When hot water flows through this, heat is applied to the resin anticorrosion core built into the joint body, and the anticorrosion core is deformed to some extent. However, since the anticorrosion core is formed such that the thickness of the tip side portion is thicker than the thickness of the back side portion, the tip side portion is not easily deformed. In addition, the back side portion, which is thinner than the tip side portion, is more likely to be deformed, and the deformation of the tip side portion is less likely to exert an influence of force on the tip side portion. Therefore, a gap is less likely to occur between the tip side portion of the anticorrosion core and the inner wall surface of the connecting pipe.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. FIG. 1 shows an embodiment of a pipe joint according to the present invention. As shown in FIG.
The pipe joint 1 includes a joint body 2 and an anticorrosion core 3. The joint body 2 is made of cast iron and has an internal thread 2 on its inner circumference.
Reference numerals 1 and 21 are formed in a tapered shape with a reduced diameter toward the central portion. Further, the anticorrosion core 3 is made of resin, and the tubular seal portion 31 is fitted and fixed to the annular groove 22 of the joint body 2 by the fixing portion 32. In addition, the tip portion 34 of the seal portion 31
Is thicker than the base end portion 33, and the inner end portion 35 is formed in a tapered shape. A resin layer 42 for anticorrosion is provided on the inner surface of the lining steel pipe 4, and a male screw 41 having the same screw diameter as the female screw 21 of the joint body 2 is formed on the outer periphery of the end so as to have a reduced diameter toward the pipe end 44. Has been done. Seal part 31
Is provided so that the outer peripheral surface thereof is in water-tight contact with the resin layer 42 when the lining steel pipe 4 is attached.

Next, the connecting work of the pipe joint 1 and the action when high-temperature hot water is passed through it will be described. First, the male screw 41 of the lining steel pipe 4 is screwed into the female screw 21 of the pipe joint 1. The pipe end 43 of the lining steel pipe 4 enters the screwing space 11 between the taper-shaped internal thread 21 and the seal portion 31, and the resin layer 42 forms the seal portion 31 of the anticorrosion core 3.
Move forward while tightening. Then, as shown in FIG. 1, when the screws are tightened with a predetermined torque and are fully inserted, the mounting is completed. At this time, a particularly large tightening force acts on the base end portion 33. This force acts in a direction to reduce the diameter of the integrally molded tip portion 34. Tightened seal part 31
At this time, as a reaction thereof, a stress to expand the resin layer 42 acts. Thus, the seal portion 31 and the resin layer 42 are in close contact with each other and cover the pipe end of the lining steel pipe 4.

The lining steel pipe 4a on the opposite side is also attached in the same manner. After construction, if hot water is passed through this part,
The sealing portion 31 of the resin anticorrosion core 3 is deformed to some extent by high heat, but the thick tip portion 34 is not easily deformed. In addition, since the base end portion 33, to which a large force is applied by the tightening, is deformed by itself, the tip end portion 34 is less affected by the tightening force and is less likely to be deformed.

As described above, even when hot water is poured into the pipe joint 1, the seal portion 31 and the resin layer 42 surely come into close contact with each other and cover the pipe end 44 of the lining steel pipe 4, so that red water comes out. There is no fear. FIG. 2 is a cross-sectional view of another embodiment of the pipe joint according to the present invention. A groove 56 is provided in the outer peripheral portion of the base end portion 53 of the seal portion 51 of the anticorrosion core 5 of FIG. 2, and the portion is thin. When piping is applied and hot water is passed through here, the proximal end portion 53 is deformed before the thicker distal end portion 54.
Therefore, the tip portion 54 is not deformed due to a large force in the diameter reducing direction, and there is no fear that red water will come out.

[0013]

Since the pipe joint according to the present invention is constructed as described above, the anticorrosion core is unlikely to be deformed even when a high-temperature liquid flows, and the liquid exudes from this core portion, and the joint body Since there is no risk of rusting or the metal part of the connecting pipe, there is less concern that red water containing rust will come out of the faucet.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a pipe joint according to the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the pipe joint according to the present invention.

FIG. 3 is a cross-sectional view of a known pipe joint.

FIG. 4 is an enlarged cross-sectional view of the pipe joint of FIG. 3 in a deformed state of the anticorrosion core.

[Explanation of symbols]

 1,5 Pipe joint 11 Threaded space 2 Joint body 21 Female thread 3 Corrosion-proof core 31 Seal part 32 Fixing part 33 Base end part (back side part) 34 Tip part (tip side part) 4 Lining steel pipe (connecting pipe) 42 Resin layer (Inner wall)

Claims (1)

[Claims] Claims: 1. A pipe joint comprising a metal tubular body having a female thread formed on its inner peripheral surface and a resin tubular anticorrosion core which is watertightly adhered to the inner wall surface of a connecting pipe connected to the joint body. In the pipe joint, the corrosion-resistant core is formed such that the thickness of the tip side portion is thicker than the thickness of the back side portion.