JP3113986B2 - Manufacturing method of anticorrosion pipe joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates relates to a method of manufacturing a corrosion pipe joint hand, details a water supply water supply pipe, hot water supply pipe, so that such chemicals and chemical plants plant piping, corrosion against the inner surface corrosion of the tube request process for producing anticorrosion pipe joint hands used for joining pipes to be.

[0002]

2. Description of the Related Art Conventionally, lining steel pipes provided with a synthetic resin layer for corrosion protection on the inner surface of the steel pipes have been widely used for water supply pipes and the like. Anticorrosion pipe joints in which a synthetic resin layer continuous with the synthetic resin layer on the inner surface of the lining steel pipe is widely used on the inner surface of the main body (Jpn.
789, etc.).

[0003]

The anticorrosion pipe joint as described above is obtained by forming a synthetic resin layer on the inner surface of a metal joint main body by an injection molding method or the like and covering (lining) the inner surface of the joint. In injection molding, synthetic resin raw materials are heated to a high temperature (15
(0 to 250 ° C.), injected into a mold by an injection molding machine, and molded. At this time, the synthetic resin layer contracts due to cooling after injection molding, and the difference in linear expansion coefficient between the metal of the joint body, for example, iron and the synthetic resin (iron: 1 × 10 ⁻⁵⁾
/ ° C, polyvinyl chloride: 7 × 10 ⁻⁵ / ° C), a gap is generally formed between the joint body and the synthetic resin layer, particularly at the end of the resin layer, and the size (diameter) increases. Significant effects will appear as the situation progresses.

When a PVC-lined steel pipe, a polyethylene powder-lined steel pipe, or the like is connected to the anticorrosion pipe joint having such a gap, if the pipe has a large thread diameter, the end of the pipe reaches the end of the resin layer. Instead, water or the like intrudes from the gap to corrode the inner surface of the metal joint main body, or when the external thread diameter of the pipe is small, the tip of the pipe pushes the synthetic resin layer into the inside and the synthetic resin layer In some cases, deformation and stress concentration occur, thereby affecting durability.

Although it is possible to eliminate the above-mentioned inconvenience by inserting a rubber ring or the like at the time of joining the pipes, the gap between the joint body and the synthetic resin layer is not completely closed. Imperfect water could not prevent water intrusion. Further, some other means such as forming a resin screw or using a lip type have been proposed, but all have problems in terms of manufacturing cost and stability of quality.

Accordingly, the present invention aims to prevent corrosion due to intrusion of water or the like from the gap due to shrinkage of the synthetic resin layer at the time of manufacturing, deformation and stress concentration of the synthetic resin layer, and improve durability. and its object is to provide a method of manufacturing a corrosion pipe joint hand possible.

[0007]

Means for Solving the Problems] To achieve the above object, the present invention is to place a metal joint body into the split mold,
After attaching an annular elastic body to the back of the threaded portion or the step at the tip of the slide core to form at the end of the metal joint body,
A slide core is inserted into a mold to form an inner surface coating cavity between the slide core and the inner surface of the metal joint body excluding the annular elastic body and the female thread portion, and then melted in the cavity. It is intended to provide a method for manufacturing a corrosion-resistant pipe joint, characterized by forming a synthetic resin layer for covering an inner surface of a metal joint main body by injecting a resin.

[0008]

[Operation] According to the above method , the gap caused by the contraction of the synthetic resin layer at the time of manufacturing is closed by the elastic force of the annular elastic body to prevent water or the like from entering when the pipe has a large thread diameter. There can in <br/>, also the pushing force when the external thread diameter of the tube is small, can be absorbed by the elastic force to prevent the deformation and stress concentration of the synthetic resin layer, further, the seal portion Can be easily manufactured to adhere to the inner surface of the lining steel pipe to improve the sealing performance with the lining steel pipe .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the drawings.

FIG. 1 shows that the present invention can be manufactured by the method of the present invention.
Sectional view illustrating an example of corrosion fittings that can, FIG. 2 is also other
Is a fragmentary cross-sectional view showing an example, FIG. 3 and FIG. 4 is an explanatory view showing an embodiment of <br/> production method of the present invention.

First, in FIG. 1, a corrosion-resistant pipe joint comprises a metal joint body 10 having female threads 11 at both ends, a synthetic resin layer 20 formed on the inner surface of the metal joint body 10,
An annular elastic body 30 having a circular cross section is mounted on the inner part of the female thread portion 11.

The metal joint body 10 is formed of a steel material for piping or the like into an appropriate shape according to the number, angle, diameter, etc. of the lining steel pipes 12 to be connected.

The synthetic resin layer 20 covers the inner surface of the metallic joint body 10 except for the annular elastic body 30 and the female thread 11, and is made of hard polyvinyl chloride, polyethylene, polybutene, ABS (acrylonitrile butadiene styrene). ) It is formed of a thermoplastic resin such as resin or polystyrene.

At both ends of the synthetic resin layer 20, a cylindrical body (core) 21 having a predetermined space between the synthetic resin layer 20 and the female thread 11 from the synthetic resin layer 20 toward the end. Are integrally formed. This tubular body 21 is used for the lining steel pipe 1.
The seal between the cylindrical body 21 and the internal thread portion 11 is set according to the thickness of the lining steel pipe 12, and the tip of the cylindrical body 21 is The inner diameter of the lining steel pipe 12 is designed to be slightly smaller than the inner diameter of the lining steel pipe 12 and equal to or slightly larger than that of the lining steel pipe 12.

The annular elastic body 30 is made of a lining steel pipe 1.
2 is connected, the shape and the arrangement position thereof are set such that the tip of the steel pipe 12 comes into contact with the steel pipe 12, and various elastic materials such as isoprene rubber (IR), chloroprene rubber (CR), and nitrile are used. Butadiene rubber (NB
R), synthetic rubber such as styrene-butadiene rubber (SBR), heat-resistant rubber such as ethylene propylene rubber (EPDM), silicon rubber, urethane rubber, viton rubber, and soft synthetic resin such as polybutene, polypropylene, and polyethylene. Although it is possible, its elasticity is most preferably about 90 in rubber hardness.

The annular elastic body 30 integrally forms a seal portion 30a that covers the outer peripheral surface of the tubular body 21 and abuts against the inner surface of the lining steel pipe, thereby improving the sealing performance with the lining steel pipe. The seal portion 30a is formed to have a slightly larger diameter than the inner diameter of the lining steel pipe so that the sealing can be performed more reliably. ing. The annular elastic body 30 has a wedge-shaped protruding edge 30c embedded in the synthetic resin layer 20 and the cylindrical body 21 at its base and the seal portion 30a to prevent the annular elastic body 30 from coming off and to prevent the seal portion 30a from being turned up. Is being planned.

The annular elastic body 30 is formed of the synthetic resin layer 2
0 before injection molding, the female thread portion 11 of the metal joint body 10
, The end of the synthetic resin layer 20
Is arranged at a position corresponding to. With this, synthetic resin
When the layer 20 is injection molded, the injected synthetic resin is
Since the elastic body 30 is compressed and deformed, the synthetic resin
When the fat shrinks, the end of the synthetic resin layer 20 and the metal joint body 10
Even if there is a gap between the elastic body 30 and the
To close the gap and prevent water from entering. In addition,
Even if the tip of the thinning steel pipe 12 is pushed in, the annular elastic body 3
0 absorbs the indentation force and deforms.
Zero deformation and stress concentration can be prevented.

FIG . 2 shows a second embodiment of the anticorrosion pipe joint.
Therefore, the annular elastic body 31 covers the outer peripheral surface of the tubular body 21.
A sealing portion 31a for covering a tip portion of the cylindrical body 21;
With the covering part 31b at the tip of the
The inner surface of the lining steel pipe is provided on the outer peripheral surface of the seal portion 31a.
Is formed with a seal protruding edge 31d that abuts the seal protruding edge 31d. Ma
In addition, similarly to the first embodiment, the resin is embedded in the synthetic resin layer 20.
A wedge-shaped protruding edge 31c is formed, and the annular elastic body 31 is detached.
The prevention and the turning-over of the cover 31a are achieved. Said
The seal projection 31d is an obstacle for screwing the lining steel pipe.
Shape and number are arbitrary as long as they can be sealed sufficiently.
And can be set appropriately. Like this
Sealing with the inner surface of the thinning steel pipe is performed at the seal projection 31d.
And screwing of the lining steel pipe in comparison with the first embodiment.
Can be easily performed.

Next, based on FIG. 3 and FIG.
A method for manufacturing the anticorrosion pipe joint will be described. In the following explanation
Illustrates the case of manufacturing a straight pipe type anticorrosion pipe joint
However, the above-mentioned elbow-type anticorrosion pipe fittings,
The fabrication can be performed in substantially the same procedure.

First, FIG. 3 shows a metal joint in a split mold 40.
This shows a state where the main body 41 is set, and a metal joint
The body 41 has a pair of slide cores inserted from both sides thereof.
Fixed at a predetermined position between 42 and 42 by a magnet 43
The inner part of the female thread part 41a of the metal joint body 41
Alternatively, the step at the tip of the slide core 42
An annular elastic body 44 is mounted in advance. Female thread
Attachment of the annular elastic body 44 to the back of 41a is performed using a metal joint.
Before setting the main body 41 to the split mold 40,
This can be done using a suitable jig, and as described above,
Attach to the tip of ride core 42 and ring simultaneously with injection molding
An elastic body 44 can be attached. In addition, the female screw part 41
The attachment of the annular elastic body 44 to the inner part of
It can be done easily.

The slide core 42 is made of the aforementioned synthetic resin.
Core 42a and cylinder 42b for forming layers and cylinder
Angi is linked with the opening and closing operation of the split mold.
With the action of an interlocking mechanism such as
Into the body 41, as shown in FIG.
To form a synthetic resin layer and a cylindrical body
A bit 45 is formed. In addition, the slide core 42 includes
A line leading to the gate 40a and the runner 40b of the split mold 40
An inner 42c is provided.

FIG. 4 shows a state in which the split molds are closed.
If the synthetic resin is injected from the gate 40a,
The synthetic resin is filled in the cavity 45 and the above-described synthetic resin layer is formed.
And a cylindrical body is formed. Next, the cooling holes (not shown)
Cooling resin is cooled and solidified by flowing cooling water, and then the mold
Is opened, the slide core 42 returns to the position shown in FIG.
The projecting mechanism such as a pin is activated, and the synthetic resin layer and the cylindrical body
Anticorrosive pipe joint having an annular elastic body 44 from the mold
break away.

As described above, before injection molding of a synthetic resin, a ring is used.
Since the elastic body 44 is set in advance, as described above,
The synthetic resin at the time of out-molding compresses and deforms the annular elastic body 44,
The gap created when the synthetic resin contracts is
Can be closed, and deformation of the synthetic resin layer during pipe joining
And stress concentration can be prevented.

[0024]

As described above, the production method of the present invention
According to this, a seal portion that covers the outer peripheral surface of the cylindrical body formed on the synthetic resin layer is formed on the annular elastic body attached to the inner portion of the female thread portion, and the annular elastic body that forms the seal portion and the cylindrical shape are formed. Easy to use anti- corrosion pipe joints that are integrally connected to the synthetic resin layer that forms the body
Can be manufactured .

The protection having the structure manufactured as described above
For esophageal joints, detach the annular elastic body from the synthetic resin layer and
The seal can be prevented from turning over the body,
To improve sealing with the lining steel pipe
ing. Therefore, a rubber ring was inserted at the time of piping construction.
Screw-in pipes for reliable corrosion protection
Can be done .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a corrosion-resistant pipe joint that can be manufactured by the method of the present invention.

FIG. 2 is a sectional view of a main part showing another example .

FIG. 3 is an explanatory view showing one embodiment of the manufacturing method of the present invention .

FIG. 4 is also an explanatory view.

[Explanation of symbols]

10, 41: metal joint body, 11, 41a: female thread, 12: lining steel pipe, 13: inner lining layer,
20 ... synthetic resin layer, 21 ... cylindrical body, 30, 31, 44 ...
Annular elastic body, 30a, 31a ... seal part, 30c, 31
c: wedge-shaped protruding edge, 40: split mold, 42: slide core

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-208385 (JP, A) JP-A 60-1667878 (JP, U) JP-A 62-194988 (JP, U) JP-A 53-208 29808 (JP, U) Japanese Utility Model 60-6045692 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16L 15 / 04,58 / 18 B29C 45/14

Claims (1)

(57) [Claims] 1. A metal joint body is arranged in a split mold.
To be formed at the end of the metal joint body,
After attaching the annular elastic body to the step at the tip of the slide core,
A ride core is inserted into a mold, and the slide core and the ring are inserted.
Inner surface of the metal joint body excluding the elastic body and the female thread
To form an inner surface coating cavity, and then
Inject molten resin into cavity
Anticorrosion characterized by forming a synthetic resin layer covering the surface
Manufacturing method of pipe fittings .