JPH07253181A - Manufacture of corrosion proof coupling - Google Patents

Abstract

PURPOSE:To manufacture a corrosion-proof coupling having an excellent oxidizing corrosion preventive function and potential difference corrosion preventive function between different metals, even though a screw no-forming part and a screw forming part of a coupling main body are covered by different layers which can exercise a corrosion-proof function and an insulating function. CONSTITUTION:After an adhesive is applied to the screw forming part 11 of a coupling main body 1 in which a corrosion-proof layer 2 is formed to a screw no-forming part, the screw 3ab of a corrosion-proof insulating member 3 having an extension 3ac at the end is screwed to the screw forming part 11, so as to arrange the extension 3ac to the opposite position of the corrosion-proof layer 2, as well as the excessive adhesive is pushed out to the end side of the screw forming part 11 by the corrosion-proof insulating part 11, and the exessive adhesive is filled between the corrosion-proof layer 2 and the extension 3ac, so as to form a blinding member 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant insulating function for a thread forming portion or a thread non-forming portion of a joint body made of a base metal such as malleable cast iron which may cause oxidative corrosion or potential difference corrosion between different metals. The present invention relates to a method of manufacturing a corrosion-resistant joint having a structure coated with a layer that exhibits the above-mentioned properties.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 7 and 8, a corrosion resistant joint in which a thread forming portion or a thread unforming portion of a joint body made of malleable cast iron or the like is covered with a layer exhibiting a corrosion inhibiting insulation effect. Was known. In the corrosion-resistant joint of FIGS. 7 and 8,
The non-threaded portion of the joint body 100, 200 is the anticorrosion layer 1
Although it is completely covered with 03, 203, in the thread forming parts 102, 202, only the portion adjacent to the thread forming part (near the end of the thread forming part) is covered with the anticorrosion layer 103. Not too much (Fig. 7), anticorrosion layer 20
3 itself forms only the portion of the thread forming portion that is adjacent to the non-thread forming portion (the end portion of the thread forming portion) (FIG. 8).

It is considered that this is because it was technically difficult to integrally form a layer exhibiting an anticorrosive action and an insulating action over the entire non-threaded portion and the threaded portion. .

Then, as in the corrosion-resistant joint shown in FIG. 7, the entire screw non-forming portion 101 and the vicinity of the end of the screw forming portion 102 on the inner peripheral surface of the joint body 100 are coated with an anti-corrosion layer 103 made of epoxy resin or the like. In the coated one,
Since it is difficult to accurately reach the male screw a of the object to be connected A to the portion where the anticorrosion layer 103 is formed, the exposed portion c is formed on the inner peripheral surface side.
1 occurred, and there was a possibility that corrosion due to oxidation might occur from here. Moreover, while such a corrosion-resistant joint is formed of a base metal such as malleable cast iron, the object A to be connected is, for example, BC in the case of a water tap.
Since it is formed of a copper alloy or the like such as No. 6, there is a possibility that potential difference corrosion may occur due to the contact of dissimilar metals in the screwed portions of both.

On the other hand, like the corrosion-resistant joint shown in FIG. 8, a corrosion-resistant layer 203 made of an injection-molded resin layer or the like is formed continuously with the thread forming portion 202 on the inner peripheral surface of the joint body 200.
03 has a screw end portion 203a which is continuous with the screw of the screw forming portion 202, and is connected to an object A such as a water tap.
The male screw a of is a screw terminal portion 203 screwed on the anticorrosion layer 203.
Although the exposed portion c1 as shown in FIG. 7 does not occur because it is screwed up to the position where it reaches a, the shrinkage of the injection-molded resin layer at the time of forming the anticorrosion layer 203 cannot be accurately predicted, and therefore the screw terminal portion 203a. It becomes difficult to make the shape accurate, and a gap is created between the joint body 200 and the anticorrosion layer 203, so that infiltration of water is unavoidable. Therefore, the potential difference corrosion in the screwed portion cannot be eliminated.

[0006]

By the way, the thread non-forming part and the thread forming part of the joint body are covered with separate layers exhibiting an anticorrosion function and an insulating function, and a layer for covering the thread non-forming part is formed. If a corrosion prevention function or insulation function is added to the connection part with the layer that covers the non-screwed part, the entire corrosion resistance of the joint body including the non-screwed part and the threaded part and the potential difference between different metals It has been found that an anticorrosion function is added. However, in a corrosion-resistant joint for pipes, since the boundary portion between the thread non-forming portion and the thread forming portion is located deep inside the internal space of the tubular joint body, the thread non-forming portion and the thread forming portion are formed in different layers. After coating with, it is difficult to form a plugging portion that exhibits a corrosion prevention function and an insulating function in the connection portion of both layers, and even if it is possible, it will be extremely inefficient work. Absent.

The invention has been made in view of the above circumstances, and in the case where the thread non-forming portion and the thread forming portion of the joint body are covered with separate layers capable of exhibiting an anticorrosive action and an insulating action, the thread forming portion is formed. Provided with a method for manufacturing a corrosion-resistant joint, in which the adhesive for bonding the layers covering the same is used to automatically form a plugged portion exhibiting a corrosion-proof function and an insulating function at the connecting portion of both layers. The purpose is to do.

[0008]

A method for manufacturing a corrosion-resistant joint according to the invention that achieves the above object, comprises an adhesive agent applied to the thread-forming portion of a joint body in which a corrosion-resistant layer is formed on the inner peripheral surface other than the thread-forming portion. After the application, the screw of the corrosion-resistant insulating member in which the extending portion is extended in the axial direction at the end of the tubular portion having the screw on the peripheral surface is extended to the screw forming portion coated with the adhesive. The adhesive is pushed forward toward the terminal end side of the screw forming portion by the corrosion-preventing insulating member, and the extension of the insulating-corrosion preventing member is made to face the corrosion-preventing layer. It is characterized in that the protruding portion is provided, and the space between the corrosion-resistant layer and the extending portion is filled with the excess adhesive agent extruded toward the terminal end side of the screw forming portion to form the plugged portion.

[0009]

In the method of manufacturing the corrosion resistant joint according to the invention, the corrosion resistant insulating member for covering the thread forming portion of the joint body is
It is prepared separately from the corrosion-resistant layer formed on the inner peripheral surface of the joint body other than the thread forming portion (that is, the thread non-forming portion) by film formation.

Then, the surplus of the adhesive applied to the screw forming portion for adhering the corrosion preventing insulating member to the screw forming portion causes the screw of the corrosion preventing insulating member to be screwed into the screw forming portion. Along with this, the excessive adhesive agent extruded to the terminal end side of the screw forming portion, and the excess adhesive extruded in this manner is disposed at the position opposite to the corrosion preventing layer by screwing the corrosion preventing insulating member into the screw forming portion. The extended portion of the insulating corrosion-resistant member and the corrosion-resistant layer are automatically accumulated and filled between them to form a plugged portion.

Therefore, in the corrosion-resistant joint manufactured by the method according to the present invention, the non-thread-formed portion of the joint body is formed of the corrosion-resistant layer, and the thread-formed portion of the joint body is formed of the corrosion-resistant insulating member, and the corrosion-resistant layer and the corrosion-resistant insulating member are extended. The adhesive is covered with the adhesive which forms a plugged portion between the protruding portion and each other. Further, the adhesive makes the screw of the anticorrosion insulating member and the screw forming portion of the joint body in close contact with each other.

[0012]

Embodiments of the invention will be described below with reference to the drawings.

FIG. 1 is a partial vertical cross-sectional view of the joint body 1, FIG. 2 is a partial vertical cross-sectional view of the corrosion-resistant insulating member 3, FIG. 3 is a partial vertical cross-sectional view of the corrosion-resistant joint manufactured by the method of the embodiment, and FIG. It is a partially broken side view of the corrosion-resistant joint manufactured by the method of the embodiment.
The corrosion resistant joint shown in FIG. 4 is manufactured using the joint body 1 of FIG. 1 and the corrosion resistant insulating member 3 of FIG. Then, in the corrosion-resistant joint manufactured according to the embodiment, the object to be connected is the water tap A ′.
Is.

The joint body 1 of FIG. 1 is made of malleable cast iron or the like, and is formed into an elbow shape as shown in FIG. 4 as a whole. A water tap A is provided on the inner peripheral surface of the opening of the joint body 1.
A female screw 11 having a larger screw diameter than the male screw a'of '(see FIG. 3) is screwed.

An anticorrosion layer 2 made of epoxy resin or the like is formed on the inner peripheral surface of the joint body 1 other than the internal thread 11 forming portion by electrostatic coating or the like. As shown in FIG. 1, the anticorrosion layer 2 is formed up to almost the top of the final peak of the female screw 11.

The anticorrosion insulating member 3 shown in FIG. 2 is made of epoxy resin, and is formed by connecting a flange portion 3b extending outward to one end of a cylindrical portion 3a having a screw on each of the inner and outer peripheral surfaces. Tubular part 3
The female screw 3aa screwed on the inner peripheral surface side of a is the water tap A '.
Is formed so as to be screwed into the male screw a'of the
The male screw 3ab screwed on the outer peripheral surface side is formed so as to be screwed into the female screw 11 of the joint body 1. Then, the female screw 3aa and the male screw 3ab are screwed, so that the wall of the thin cylindrical portion 3a has a wavy vertical cross section. On the other hand, at the other end of the tubular portion 3a, an extending portion 3ac having an inner peripheral diameter equal to the root diameter of the male screw 3ab is axially extended.

The anticorrosion insulating member 3 shown in FIG. 2 has an extended portion 3a.
With c as the front, the joint body 1 of FIG. 1 is screwed into the internal thread 11 to which the adhesive is applied. That is, after the adhesive is applied to the female screw 11 of the joint body 1, the male screw 3ab of the anticorrosion insulating member 3 is screwed onto the female screw 11 to which the adhesive is applied, with the extending portion 3ac in front. . When the male screw 3ab of the anticorrosion insulating member 3 is screwed into the female screw 11 of the joint body 1 in this manner, the anticorrosive insulating member 3 and the joint body 1
A thin film adhesive layer (not shown in FIG. 3) is interposed between the female screws 11 to bond the two, and the gap between the two is completely filled. In this case, even if there is a gap between the male screw 3ab and the female screw 11 due to a molding error or the like of the male screw 3ab of the anticorrosion insulating member 3, the adhesive remains in the entire screwed portion including the gap and remains. An adhesive forms the adhesive layer. On the other hand, the adhesive applied to the female screw 11 but not left in the screwing portion with the male screw 3ab becomes a surplus adhesive, and this surplus adhesive is screwed together to prevent corrosion-resistant insulating member 3 Is pushed out toward the terminal end side of the female screw 11. Therefore, when the extending portion 3ac of the insulating and corrosion protection member 3 is provided at a position facing the corrosion preventing layer 2 by screwing the two, it is formed between the corrosion preventing layer 2 and the extending portion 3ac. The triangular space portion 4 is filled with the excess adhesive agent extruded toward the terminal end side of the female screw 11 to form the filling portion 5 as shown in FIG. The collar portion 3b abuts the end surface of the joint body 1 in a completely screwed state by screwing the male screw 3ab onto the female screw 11 of the joint body 1 to cover it.

By the way, the anticorrosion insulating member 3 is formed as a single unit separately from the anticorrosion layer 2 formed on the joint body 1. The forming method is injection molding or blow molding. May be rotational molding, regardless of the type. The anticorrosion insulating member 3 can be formed of a thermosetting resin such as an epoxy resin, a urea resin, a melamine resin, a polyolefin resin, a thermoplastic resin such as vinyl chloride or nylon, or an inorganic material such as ceramics.

In the corrosion-resistant joint manufactured by the method described above, when the strength of the corrosion-resistant insulating member 3 is sufficiently large, as shown in FIG. 5, the female screw 3aa of the cylindrical portion 3a is formed.
It is preferable that the pitches P1 and P2 of the male screw 3ab are made to be the same and the thicknesses t1 and t2 of the opposing walls formed by the flanks of the respective screw threads are made the same. This is because when the corrosion-resistant insulating member 3 is molded as a single body, the resin flow is good, and it is easily screwed into the joint body 1 after molding. However, when the water tap A ′ is connected to this corrosion-resistant joint, as shown in FIG. 3, a propulsive force F in the direction opposite to the advancing direction X of the water tap A ′ in the female screw 3aa is applied. If the thicknesses t1 and t2 are the same as described above, it is considered that when the strength of the anticorrosion insulating member 3 is not sufficient, the portion of the thickness t1 corresponding to the flank facing the traveling direction X side is likely to be damaged. To be Therefore, as shown in FIG. 6, the pitch P1 of the female screw 3aa may be slightly shifted in the traveling direction X side with respect to the pitch P2 of the male screw 3ab, and the thickness t1 may be made larger than the thickness t2.

The anticorrosion joints of FIGS. 3 and 4 manufactured by this method are coated with a sealing material on the surface of the male screw a'of the water tap A'to be connected at the time of construction, and then the male screw a ' Is screwed into the female screw 3aa of the anticorrosion insulating member 3 to be connected to the water tap A '. In the corrosion-resistant joint to which the water tap A ′ is connected in this manner, the thread-unformed portion of the joint body 1 is formed by the corrosion-resistant layer 2 so that the female screw 11 of the joint body 1 is formed.
Is completely covered by the anticorrosion insulating member 3 with the adhesive forming the filling portion 5 between the anticorrosion layer 2 and the extending portion 3ac of the anticorrosion insulating member 3. Therefore, corrosion due to oxidation is prevented. Further, since the adhesive layer is interposed between the anticorrosion insulating member 3 and the female screw 11 of the joint body 1 and the two are in close contact with each other, infiltration of water between them is prevented, and this is formed by the adhesive that collects in the space 4. This is further ensured by the presence of the clogging part 5 which is formed. Further, the presence of the corrosion-resistant insulating member 3 prevents the corrosion of the potential difference between different metals in the screwed portion of the corrosion-resistant joint and the connected object, and further, on the outer peripheral side of the corrosion-resistant joint, the end surface of the joint body 1 and the connected object. It is also prevented that water drops and the like are accumulated between them and are electrically short-circuited.

In the embodiment, the method of manufacturing the corrosion-resistant joint provided with the elbow-shaped joint body 1 has been described, but the corrosion-resistant joint manufactured by the method of manufacturing the corrosion-resistant joint according to the invention is not limited to this. Of course, the manufacturing method of the present invention can be applied to any shape such as a socket type shape.

[0022]

As is apparent from the above description, according to the present invention, the thread non-forming portion and the thread forming portion of the joint body are provided with separate layers (corrosion-resistant layer and corrosion-resistant insulating layer) capable of exhibiting a corrosion-preventing action and an insulating action. Although it is coated with a material), an adhesive for bonding a layer (corrosion-proof insulation member) that covers it to the thread forming part is used, and the corrosion-proof function and insulation are automatically applied to the connection part of these two layers. Since the clogging portion that exhibits the function is formed, it becomes possible to manufacture a corrosion-resistant joint having excellent workability and excellent oxidative corrosion prevention performance and potential difference corrosion protection between different metals without technical difficulties.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a joint body.

FIG. 2 is a partial vertical cross-sectional view of a corrosion-resistant insulating member.

FIG. 3 is a partial vertical cross-sectional view of a corrosion-resistant joint manufactured by the method according to the embodiment of the present invention.

FIG. 4 is a partially cutaway side view of a corrosion-resistant joint manufactured by the method according to the embodiment of the present invention.

5 is a partially enlarged view of FIG. 3 for explaining a corrosion-resistant insulating member.

FIG. 6 is a cross-sectional explanatory view showing a modified example of the anticorrosion insulating member.

FIG. 7 is a vertical cross-sectional view of a main part of a conventional corrosion-resistant joint.

FIG. 8 is a longitudinal sectional view of a main part of a conventional corrosion-resistant joint.

[Explanation of symbols]

 1 Joint body 2 Corrosion-proof layer 3 Corrosion-proof insulating member 3a Cylindrical part 3ab Male screw (screw) 3ac Extending part 5 Filling part 11 Female screw (screw forming part)

Claims (1)

[Claims] Claim: What is claimed is: 1. An adhesive is applied to the thread forming portion of a joint body in which an anticorrosive layer is formed on the inner peripheral surface other than the thread forming portion, and then a shaft is attached to an end of a tubular portion having a thread on the peripheral surface. The screw of the anticorrosion insulating member in which the extending portion is extended in the direction is screwed into the thread forming portion to which the adhesive is applied, with the extending portion in front, and the anticorrosion insulating material is formed. A member pushes the excess adhesive to the terminal end side of the thread forming portion, and the extension portion of the insulating corrosion-resistant member is arranged at a position opposite to the corrosion-resistant layer so that the corrosion-resistant layer and the extension portion are separated from each other. Is filled with an excess of the adhesive agent extruded toward the terminal end side of the thread forming portion to form a plugged portion.