JPH0694186A - Manufacture of insulated corrosion-resistant joint - Google Patents

Abstract

PURPOSE:To prevent fluid leakage from screwed sections by inserting core molds into a joint and filling molten resin into a cavity between the outer periphery of the core molds and the inner periphery of the joint after a metal female thread member is screwed into the end inner surface of the metal joint through a synthetic resin layer. CONSTITUTION:The outer periphery of a metal female thread member 2 is coated integrally with a synthetic resin layer 3 such as vinyl chloride resin, polyethylene, etc., and male threads 31 are formed on the outer periphery of it. The female thread member 2 is screwed into a female threads 11 formed on the inner periphery of one end of a metal joint 1 to tighten securely a rubber ring 4 between the end surface of the joint 1 and a flange 32 of the female thread member 2. Next, a core mold 6a is inserted into the female screw member 2 screwed into one end of the joint 1, and a core mold 6b comprising an inner mold 61 and a cylindrical mold 62 is inserted into the other end. Thus a molten metal is filled from a gate 60 into a cavity (a) formed between the inner periphery surface of the joint 1 and the core metal molds 6a and 6b to complete a metal joint 1 of which inner surface is covered with the synthetic resin layer 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an anticorrosion joint which prevents electrolytic corrosion due to contact of different metals and generation of red water due to oxidative corrosion.

[0002]

2. Description of the Related Art The applicant of the present invention has previously proposed, in Japanese Utility Model Application No. 2-116012, an insulating and corrosion-proof joint for connecting a water tap made of gun metal and a lining steel pipe. However, this insulating and corrosion-proof joint includes a metal joint in which the inner peripheral surface of the joint excluding female threads is covered with a synthetic resin layer, and a metal female thread member in which the outer peripheral surface is covered with a synthetic resin layer and a male screw is provided on the outer peripheral surface After preparing, since the male screw of the metallic female screw member was screwed into the female screw of the metallic joint to be connected,
If the screwing is weak, there is a risk that the fluid in the pipe may leak from the screwing surface between the male screw and the female screw.

The present invention has solved the above problems and provides a method for producing an anticorrosion joint which can surely prevent electrolytic corrosion and oxidative corrosion and never leak fluid in a pipe.

[0004]

According to the present invention, first, an outer peripheral surface of a metallic female screw member is covered with a synthetic resin layer, and a male screw is provided on the outer peripheral surface of the synthetic resin layer. Next, the male screw of this metallic female screw member is screwed into the female screw provided on the inner peripheral surface of the end of the metallic joint. Therefore, the core mold is inserted into the metal joint, and the molten resin is filled in the cavity formed between the outer peripheral surface of the core mold and the inner peripheral surface of the metal joint. is there.

[0005]

The metal joint and the female metal screw member are electrically insulated by the synthetic resin layer. Further, the synthetic resin layer is integrally fusion-bonded to the synthetic resin layer covering the inner peripheral surface of the metal joint.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional view showing a developed state of a joint component used in the present invention, FIG. 2 is a sectional view showing a state where a core mold is set in a metal joint, and FIG. It is a cross-sectional view, in which 1 is a metal joint made of cast iron or the like. The metal joint 1 is an elbow joint whose both ends are curved at 90 degrees, and female threads 11 are provided on the inner peripheral surface of each end. Reference numeral 2 is a metallic female screw member made of gun metal or the like, and an internal screw 21 is provided on the inner peripheral surface of the metallic female screw member 2.

In the present invention, first, the outer peripheral surface of the metallic female screw member 2 is integrally covered with a synthetic resin layer 3 of vinyl chloride resin, polyethylene or the like, and the male screw 31 is attached to the outer peripheral surface of the synthetic resin layer 3.
To provide. A flange-shaped collar 32 is provided on the outer periphery of one end of the synthetic resin layer 3, and one or more protrusions 33 extending in the axial direction are formed on the other end.

Next, the male screw 31 of the metallic female screw member 2 is screwed into the female screw 11 provided on the inner peripheral surface of one end of the metallic joint 1, and the end face of the metallic joint 1 and the collar 32 of the metallic female screw member 2 are joined together. Firmly tighten the rubber ring 4 interposed therebetween. Therefore, the metal joint 1 is set in an injection molding machine, the core metal mold 6a is inserted into the metal female screw member 2 screwed to one end of the metal joint 1, and the inner mold 61 is attached to the other end. Insert the core mold 6b consisting of the cylindrical mold 62,
The inclined surfaces provided at the tips of the core molds 6a and 6b are brought into contact with each other.

In this way, after the cavity a is formed between the outer peripheral surfaces of the core molds 6a and 6b inserted into the metal joint 1 and the inner peripheral surface of the joint, the gate provided on the core mold 6a is formed. From 60, the cavity a is filled with molten resin. Then, the cavity a is filled with the molten resin, and the synthetic resin layer 3 covering the outer peripheral surface of the metallic female screw member 2 is formed.
And the protrusion 33 are integrally fused and joined. Therefore,
Wait for the molten resin to cool and solidify, then the core mold 6a,
When 6b is extracted, the corrosion-resistant joint shown in the sectional view of FIG. 3 is obtained.

In this insulating and corrosion-resistant joint, the female screw 11 of the metal joint 1 and the female female screw member 2 are screwed together via the synthetic resin layer 3, and the synthetic resin layer 3 is located on the inner peripheral surface of the joint on the inner side of the female screw 11. Is fused integrally with the synthetic resin layer 5 covering the. Further, since the protrusion 33 extending from the synthetic resin layer 3 is integrally fused with the synthetic resin layer 5 and functions as a rotation stopper for the metallic female screw member 2, the metallic female screw member 2 is provided with a water tap or the like. When screwed, there is no risk that the metallic female screw member 2 will slip out and slip out, or the fluid in the pipe will leak from the screwing face between the female screw 11 and the male screw 31 provided on the outer peripheral surface of the synthetic resin layer 3.

At the other end of the anticorrosion joint, a tubular shape is formed which extends from the synthetic resin layer 5 covering the inner peripheral surface of the metal joint 1 and has a predetermined gap with the female screw 11. Since the body 51 is provided, when the end portion of the lining steel pipe is screwed into the female screw 11, the inner peripheral surface of the pipe end portion is in close contact with the outer peripheral surface of the tubular body 51, and leakage of fluid in the pipe is reliably prevented. .

In the above embodiment, the case where the metal joint is the elbow joint is illustrated, but the present invention is not limited to this elbow joint, and may be applied to a socket joint, a T-shaped joint and the like. it can.

[0013]

As described in detail above, according to the present invention, the internal thread of the metal joint and the internal thread member of the metal are insulated by the synthetic resin layer, so that electrolytic corrosion due to contact of dissimilar metals is surely prevented. Moreover, since the inner peripheral surface of the metal joint is integrally covered with the synthetic resin layer, the generation of red water due to oxidative corrosion is reliably prevented. Further, in the present invention, the synthetic resin layer interposed between the female screw of the metal joint and the metal female screw member and the synthetic resin layer covering the inner peripheral surface of the metal joint are integrally fusion-bonded to each other. Therefore, there is no possibility that the metallic female screw member idles when the water tap or the like is screwed into the metallic female screw member, or the fluid in the pipe leaks from the screwing surface with the metallic joint.

[Brief description of drawings]

FIG. 1 is a sectional view showing a developed state of a joint part used in the present invention.

FIG. 2 is a cross-sectional view of a state in which a core mold is set inside a metal joint.

FIG. 3 is a cross-sectional view of an insulation and corrosion protection joint obtained according to the present invention.

[Explanation of symbols]

 1 Metal Joint 2 Metal Female Thread Member 3 Synthetic Resin Layer 4 Rubber Ring 5 Synthetic Resin Layer a Cavity 6a Core Mold 6b Core Mold

Claims (1)

[Claims] 1. A metallic female screw member is screwed into a female screw provided on an inner peripheral surface of an end of a metallic joint via a synthetic resin layer, and an inner peripheral surface of the joint on the inner side of the female screw is covered with a synthetic resin layer. In manufacturing the insulated corrosion-resistant joint, first, the outer peripheral surface of the metallic female screw member is coated with a synthetic resin layer and the male screw is provided on the outer peripheral surface of the synthetic resin layer, and then the male screw of the metallic female screw member is made of the metal. After screwing into the female thread of the joint,
A core metal mold is inserted into a metal joint, and a molten resin is filled in a cavity formed between the outer peripheral surface of the core metal mold and the inner peripheral surface of the metal joint. Production method.