JPH0587284A - Pipe joint for plastic pipe multipoint connection and method thereof - Google Patents

Abstract

PURPOSE:To perform a multipoint connection which is firm and high in watertightness by manufacturing a pipe joint with form memory resinoid, making a main pipe setting part so as to be subjected to heat fusion in a state of holding more than a semicircle of the main pipe outer circumference with restoring force to the stored form, and ensuring the heat fusion between the main pipe setting part and the main pipe. CONSTITUTION:Such a form as a dotted line holding a main pipe 11 is stored in a main pipe setting part 23 of a form memory resinoid molding body. When, a diametral expanding part 27, where a branch pipe 13 is insertable, is installed in a tip part of a branch pipe connection 25, having a cylindrical form of an inner diameter being less than an outer diameter of the branch pipe 13 stored in the diametral expanding part 27. Moreover, two heat fusing resinoid layers 29, 31 are solidly installed on each inner surface of the main pipe setting part 23 and the diametral expanding part 27. In succession, the main pipe setting part 23 is straddled on the main pipe 11 and, after it is heated and attached to the main pipe 11, a hole is bored in the main pipe 11 in the branch pipe connection, connecting the branch pipe 13 to the main pipe. With this constitution, connection of the branch pipe can be done without cutting the main pipe, thus setting to the main pipe becomes strengthened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint used for connecting a branch pipe to a main pipe made of plastic.

[0002]

2. Description of the Related Art Recently, plastic pipes have been used in place of metal pipes for water pipes, hot water supply pipes, hot spring transport pipes, etc.
For example, polyolefin pipes (polyethylene pipes, etc.) have come to be used. Compared to metal pipes, polyolefin pipes are lighter and easier to handle, have excellent corrosion resistance and chemical resistance, have less scale adhesion, are long and require few connection points, have good flexibility, etc. There are advantages.

Branch connection is indispensable even in a piping system using such a plastic pipe. Conventionally, most of the branch connections of plastic pipes are performed as follows. For example, when the branch pipe 13 is to be connected to the existing main pipe 11 as shown in FIG. 13, the main pipe 11 is cut by a predetermined length at the branch portion as shown in FIG. Then, as shown in FIG. 15, the cut end of the main pipe 11 is connected to the main pipe connection ports 17A, 17 of the T-branch pipe joint 15.
Insert into B and fuse, and further, as shown in FIG. 16, insert the branch pipe 13 into the branch pipe connection port 19 of the T branch pipe joint 13 and fuse.

The above is the case where a new branch pipe is connected to an existing main pipe, but when both the main pipe and the branch pipe are new,
The main pipe is cut in advance according to the length of the branch section, the main pipe is piped while alternately connecting the main pipe and the T branch pipe joint, and then the branch pipe is connected to each T branch pipe joint. The method is taken.

However, the conventional branch connection method has the following problems. In most cases where the main pipe is already installed, it is difficult to insert the cut end into the T-branch pipe joint after cutting the main pipe, because the main pipe is almost always fixed to a building or the like. This is because the cut length of the main pipe must be shorter than the length of the T-branch pipe joint, and therefore the main pipe must be bent in order to insert the cut end of the main pipe into the T-branch pipe joint. However, it is difficult to bend the main pipe when the main pipe is fixed on both sides of the branch portion. Deflection of the main becomes more difficult as the diameter of the main increases.

In addition, when the main pipe is newly installed, it is necessary to prepare a main pipe that is cut according to the length of the branching section, which not only takes time but also an error in the cut dimension is found at the time of piping. There is no choice but to interrupt the piping work, and the piping work is regulated, so the piping work is troublesome.

By the way, for metal pipes for water supply, a method has been established in which a branch pipe is connected to an existing main pipe while flowing water. This method is called the uninterrupted water communication method.
It is expected that this uninterrupted water connection method will be introduced for water pipes as well, but there is no established method at this time.

[0008] When introducing the uninterrupted water connection method into a plastic pipe for water supply, the first example of the parts is
It is a heat fusion joint of the same shape as the saddle and service chee specified for JIS K 6775 gas polyethylene pipe joints. However, this joint has a drawback that it is difficult to perform heat fusion to the main pipe and requires skill.

The second is an electrofusion joint (hereinafter referred to as an EF joint) having the same shape as the saddle containing a heating wire and the service cord containing a heating wire defined in the same JIS K 6775 gas polyethylene pipe fitting. Since this joint can be heat-sealed with the main pipe simply by electrically heating the heating wire built in the joint surface with the main pipe, the welding work is simple, but the heat-welding with this heating wire Since only melts the inner surface of the joint and the outer surface of the main pipe, it is necessary that the inner surface of the joint and the outer surface of the main pipe are in close contact with each other during heat fusion. However, the cross section of the main pipe is often deformed during manufacturing or transportation.For example, if the main pipe is flat even a little, a gap is created between the main pipe and the inner surface of the joint to obtain a good fusion state. I can't.

[0010]

SUMMARY OF THE INVENTION The present invention provides a plastic pipe branch connection pipe joint and a plastic pipe branch connection method using the same, which solves the above problems.

In the plastic pipe branch connection pipe joint according to the present invention, a saddle-shaped main pipe attachment portion to be attached to a plastic main pipe and a tubular branch pipe connection portion to connect the branch pipe are integrally formed. Made of a shape memory resin molded body, the main pipe attachment part has a perimeter longer than half the outer circumference of the main pipe, and has a saddle shape in which at least the hem is widened to straddle the main pipe. The main pipe mounting portion holds the main pipe and memorizes the shape in which the inner peripheral surface is in close contact with the outer peripheral surface of the main pipe, and the main pipe mounting portion is memorized on the inner surface of the main pipe mounting portion. It is characterized in that a heat-fusible resin layer, which is melted at the temperature at which the shape is restored and is fused to the outer surface of the main pipe, is integrally provided.

Further, the branch pipe connecting portion has a diameter-increasing portion into which a branch pipe can be inserted, and the diameter-increasing portion has a cylindrical shape having an inner diameter equal to or smaller than the outer diameter of the branch pipe. And the inner surface of the expanded diameter portion is integrally provided with a heat-fusible resin layer that melts at the temperature at which it is restored to the memory shape and fuses to the outer surface of the branch pipe. It is desirable to keep it.

Next, in the method for branching and connecting a plastic pipe according to the present invention, after the main pipe mounting portion of the pipe joint having the above-mentioned structure is straddled over the plastic main pipe, the main pipe mounting portion is heated to restore the memory shape. Then, the heat-fusible resin layer on the inner surface is fused to the main pipe, and then a hole is formed in the main pipe in the branch pipe connecting portion, and then the branch pipe is connected to the branch pipe connecting portion. It is characterized by

[0014]

The shape-memory resin is first shaped into a certain shape by forming a mold during polymerization, and then the molded body is heated to a temperature not lower than the glass transition temperature (Tg) to form another shape. Subsequent shaping, if cooled while maintaining its shape, the primary shaped shape can be memorized in the molded body after secondary shaping,
When the molded product after the secondary shaping is subsequently heated to a temperature of the shape recovery temperature or higher (usually Tg or higher), it has a property of returning to the primary shaped shape.

The pipe joint of the present invention utilizes this property. That is, the saddle-shaped main tube mounting portion is first shaped into a shape that closely adheres to the outer peripheral surface of the main tube, and then heated,
The secondary shape is a saddle shape in which at least the hem is widened so as to be able to straddle the main pipe. Therefore, when the main pipe mounting portion is laid across the main pipe and heated, the main pipe mounting portion restores to the primary shaped shape (memory shape), and the main pipe is held and the inner peripheral surface of the main pipe mounting portion is the outer peripheral surface of the main pipe. It becomes a shape that sticks to. Since the inner surface of the main pipe mounting portion is provided with a heat-fusible resin layer that melts at the temperature at which it is restored to the memory shape,
This causes the main tube attachment portion to be heat-sealed to the main tube.

After that, a branching tool is inserted into the branch pipe connecting portion to make a hole in the main pipe, and then the branch pipe is connected to the branch pipe connecting portion by an appropriate method to complete the branch connection. In other words, since it is not necessary to cut the main pipe in this connecting step, the branch connecting work becomes extremely simple.

The above properties can also be used in the branch pipe connection. That is, first, the tubular branch pipe connection part is first shaped into a cylindrical shape having an inner diameter equal to or smaller than the outer diameter of the branch pipe, and then heated to expand the inner diameter into which the branch pipe can be inserted. (Secondary shaping). By doing this, after inserting the branch pipe into the expanded portion, the expanded portion is heated to restore the primary shaped shape (memory shape) so as to be in close contact with the branch pipe, and at the same time, the inner surface is heat-sealed. The branch pipe can be easily connected only by melting the heat-resistant resin layer and heat-sealing it to the branch pipe.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 show a pipe joint for branching a polyolefin pipe according to an embodiment of the present invention. This pipe fitting
Reference numeral 21 denotes a shape-memory resin molded body in which a saddle-shaped main pipe attachment portion 23 straddling the polyolefin main pipe 11 and a tubular branch pipe connection portion 25 connecting the polyolefin branch pipe 13 are integrally formed. It consists of

As the shape memory resin, for example, polynorbornene (a ring-opening polymer of a norbornene-based monomer), polyester, polyurethane, epoxy resin, nylon or the like can be used. Among them, the thermosetting polynorbornene is heat-fused. It is particularly preferable because the same kind of polymer as the polyolefin tube can be used for the resin layer, the glass transition temperature (Tg) is high, and the selection and setting of Tg is easy.

The main pipe mounting portion 23 is formed such that the length (peripheral length) along the saddle shape from one side edge to the other side edge is longer than the half circumference of the outer peripheral surface of the main pipe 11, and It has a saddle shape with the hem expanded like a solid line to straddle,
The main pipe mounting portion 23 holds the main pipe 11 and stores a shape such as a dotted line in which the entire inner peripheral surface is in close contact with the outer peripheral surface of the main pipe 11.

In order to store the shape of the saddle-shaped main tube mounting portion 23 in the shape of the dotted line, the main tube mounting portion 23 is first shaped (polymerized) into the shape of the dotted line, and then the temperature is usually higher than Tg. Then, the secondary shape is applied to the saddle shape as shown by the solid line, and the shape is maintained and cooled. As a result, the saddle-shaped main tube mounting portion 23 is given the property of returning to a memorized shape (shape like a dotted line) when heated to a temperature of Tg or higher.

The branch pipe connecting portion 25 has an enlarged diameter portion 27 into which the branch pipe 13 can be inserted, and the enlarged diameter portion 27 has an inner diameter equal to or smaller than the outer diameter of the branch pipe 13. The cylindrical shape having is stored. In order to memorize the cylindrical shape in the expanded diameter portion 27 of the branch pipe connecting portion 25, the branch pipe connecting portion is formed into a straight tube at the time of the primary shaping, and then heated to a temperature of Tg or higher and the tip portion. The diameter may be expanded (secondarily shaped) to an inner diameter larger than the outer diameter of the branch pipe, and cooled while maintaining its shape. As a result, the expanded diameter portion 27 has the property of returning to the primary shape when heated to a temperature of Tg or higher.

Further, heat-fusible resin layers 29 and 31 are integrally provided on the inner surfaces of the main pipe mounting portion 23 and the expanded diameter portion 27, respectively. These heat-fusible resin layers 29 and 31 are attached to the main pipe mounting portion.
It is made of a material that melts at the temperature at which the 23 and the expanded diameter portion 27 are restored to the memorized shape and is fused to the outer surfaces of the main pipe 11 and the branch pipe 13.

The heat-fusible resin layers 29 and 31 may be made of any material that can be heat-sealed to the polyolefin pipe to be connected. The material obtained is preferred. For example, when polynorbornene is used as the shape memory resin, high density polyethylene, medium density polyethylene, low density polyethylene, polybutene-1, ethylene-propylene copolymer, polypropylene, ethylene-vinyl acetate copolymer (EVA), ethylene Polymers having an olefin as a main component such as an acrylic ester copolymer (EAA) and an ethylene-ethylacrylic acid copolymer (EEA) can be used. These may be used alone or in appropriate combination of two or more. Further, when using a resin that does not fuse to the shape memory resin molded body, it is necessary to devise such as applying an adhesive to the outer circumference of the heat fusible resin layers 29 and 31 to mold the shape memory resin.

The heat-fusible resin layer 31 on the side of the branch pipe connecting portion 25
It is more convenient not only to provide the enlarged diameter portion 27 but also to provide the entire inner surface of the branch pipe connecting portion 25 in terms of manufacturing. This is because the heat-fusible resin layer 31 is used when the pipe joint is molded (primary molding).
This is because the heat-fusible resin pipe for use in molding the inner surface of the branch pipe connection portion 25 can be used.

Next, a method of branching and connecting a polyolefin pipe with the pipe joint 21 will be described. First, saddle-shaped main tube mounting part 23
Over the main pipe 11, and the main pipe mounting portion 23 is heated to a temperature of Tg or higher. Then, the main pipe mounting portion 23 is restored to the memory shape, and as shown in FIG. 3, the entire inner peripheral surface is brought into close contact with the outer peripheral surface of the main pipe 11, and the heat-fusible resin layer 29 is melted and the main pipe 11 Heat fusion with the outer surface. As a result, the main pipe mounting portion 23 is
It was firmly and watertightly attached to.

Next, a hole making tool is inserted into the branch pipe connecting portion 25 to make a hole 32 in the main pipe 11. This drilling is the main 11
It is desirable to perform it while sucking air so that chips do not get inside. Finally, the branch pipe 13 is inserted into the expanded diameter portion 27, and the expanded diameter portion 27 is heated to a temperature of Tg or higher. Then, the expanded diameter portion 27 is restored to the memory shape and adheres to the outer peripheral surface of the branch pipe 13 as shown in FIG.
Heat fusion with the outer surface of the. As a result, the branch pipe 13 is firmly and watertightly connected to the branch pipe connecting portion 25. This completes the branch connection.

Next, another embodiment of the present invention will be described with reference to FIGS.
Will be described. 4 and 5 show the state after the shape memory processing, and FIG. 6 shows the state before the shape memory processing. That is, the pipe joint 21 of the present embodiment shown in FIGS. 4 and 5 memorizes the shape of FIG. This pipe joint 21 is different from the above embodiment in that the distance between both side edges of the main pipe mounting portion 23 is smaller than the outer diameter of the main pipe (see FIG. 4), and the branch pipe connecting portion 25 is made slightly longer. That is, the ball valve 33 is built in the middle part thereof. The handle 35 of the ball valve 33 is exposed to the outside.

The main pipe mounting portion 23 is subjected to shape memory processing as shown in FIG.
If it is molded into such a shape, the main pipe mounting part 23 will be elastic and deformed so that both side edges will open slightly when straddling the main pipe, and then it will return to its original shape. The stability is improved and the installation work becomes easier. It is desirable that the distance between both edges be at least 75% and less than 100% of the outer diameter of the main pipe.

Further, the reason why the ball valve 33 is built in the branch pipe connecting portion 25 is to allow the branch pipe to be connected while the water is flowing through the existing main pipe. Ie this fitting
In the case of making a branch connection by using 21, the main pipe mounting portion 23 is attached to the main pipe in the same manner as in the above embodiment, and then the ball valve 33 is opened (set as shown in FIG. 4).
Drill the main pipe through the 33 holes. When a hole is made in the main pipe, water spouts, but the water flow causes chips to flow out.

When the main pipe has a hole, the drilling tool is pulled out, and the ball valve 33 is immediately closed (rotated by 90 °) to stop the jet of water. After that, a branch pipe is connected to the expanded diameter portion 27 in the same manner as in the above-described embodiment, the pipe on the side of the branch pipe is completed, and then the ball valve 33 is opened. In this way, it becomes possible to connect the branch pipes with water flowing in the main pipes.

Since the structure and method of use other than the above are the same as those of the above-mentioned embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted.

FIG. 7 shows still another embodiment of the present invention.
This pipe joint 21 is also for connecting a branch pipe while allowing water to flow through the existing main pipe. In this pipe joint 21, the main pipe mounting portion 23 has the same structure as that of the embodiment of FIG. 1, but the branch pipe connecting portion 25 has a vertical portion 25 which rises vertically from the main pipe mounting portion 23.
a and a horizontal portion 25b extending laterally from the vertical portion, and the structure is such that the drilling part 37 is screwed into the vertical portion 25a. The heat-sealable resin layer 29 is provided on the inner surface of the main pipe attachment portion 23, and the expanded diameter portion 27 having the heat-sealable resin layer 31 on the inner surface is formed at the tip of the branch pipe connection portion 25. That is the same as in each of the above embodiments.

As shown in FIG. 8, the perforating part 37 has a right-angled passage 39 through which water passes in the lower half portion as shown by an arrow, and a serrated blade 41 for making a hole in the main pipe at the lower end. And has a male screw portion 43 on the outer periphery of the upper half portion. On the inner surface of the upper end of the vertical portion 25a of the branch pipe connecting portion, a female screw portion 44 to which the male screw portion 43 of the hole making component 37 is screwed is formed.

This pipe joint 21 is used as follows. First, as shown in FIG. 9, the main pipe mounting portion 23 is straddled over the main pipe 11 in which water is still flowing, and the branch pipe is connected to the expanded diameter portion 27 of the branch pipe connecting portion 25.
Insert 13. Next, the main pipe mounting portion 23 and the expanded diameter portion 27 are heated to restore the memory shape as shown in FIG.
And heat-bond to the branch pipe 13. Then, as shown in Fig. 11, screw in the drilling part 37, and use the blade 41 at the tip to
Make a hole in 11. As a result, the main pipe 11 and the branch pipe 13 communicate with each other through the passage 39 of the punching part 37. Chips generated during drilling are branched by the water flow flowing from the main pipe 11 to the branch pipe 13.
It is discharged to the outside through 13.

FIG. 12 shows another embodiment of the present invention.
In this pipe joint 21, in order to facilitate heating of the main pipe mounting portion 23, the heat-fusible resin layer 29 is formed of a conductive resin and is integrated with the main pipe mounting portion 23. Reference numeral 47 is an electrode attached to both ends of the conductive heat-sealing resin layer 29, and 49 is a lead wire. In this case, no hole is formed in the portion of the main pipe mounting portion 23 located inside the branch pipe connecting portion 25. This is for making the electric resistance of the heat-sealing resin layer 29 uniform (preventing holes in the heat-sealing resin layer 29).

This pipe joint 21 restores the main pipe mounting portion 23 to the memorized shape by electrically heating the conductive heat-sealing resin layer 29 after the main pipe mounting portion 23 is straddled over the main pipe. At the same time, the heat-fusible resin layer 29 is fused to the main pipe. The configuration other than the above and the method of use are the same as in the embodiment of FIG.

In each of the above-described embodiments, the diameter-expanded portion 27 subjected to shape memory processing is provided at the tip of the branch pipe connecting portion 25. However, the tip of the branch pipe connecting portion 25 has such an enlarged portion. A structure in which the heat-sealing resin layer is simply provided on the inner surface may be used without providing the heat-sealing resin layer. However, in this structure, it is necessary to make the clearance with the main pipe considerably small.

[0039]

As described above, according to the present invention, the branch pipe can be connected without cutting the main pipe. Therefore, in the case where both the main pipe and the branch pipe are newly installed, the main pipe is long. It is possible to efficiently perform the piping work by using the plastic pipe of the above. In addition, when the main pipe is already installed or the branch pipe is newly installed, not only can the branch pipe be connected easily, but also water etc. is poured into the main pipe. It is also possible to perform branch connection work as it is.

In particular, according to the present invention, the pipe joint is made of a shape memory resin, and the main pipe mounting portion is heat-sealed in a state of holding a half or more of the outer periphery of the main pipe by the restoring force to the memorized shape. Therefore, fusion between the main pipe mounting portion and the main pipe becomes reliable, and a strong and highly watertight branch connection can be performed.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a pipe joint according to an embodiment of the present invention.

FIG. 2 is a side view of the pipe joint of FIG.

3 is a cross-sectional view showing a state in which a branch pipe is connected to a main pipe with the pipe joint of FIG.

FIG. 4 is a partially cutaway front view of a pipe joint according to another embodiment of the present invention.

5 is a side view of the pipe joint of FIG.

6 is a sectional view of the pipe joint of FIG. 4 before a shape memory process is performed.

FIG. 7 is a front view of a pipe joint according to still another embodiment of the present invention.

8 is a front view of a drilling part used in the pipe joint of FIG. 7. FIG.

9 is a front view showing a first stage of a branch connection method using the pipe joint of FIG. 7. FIG.

10 is a front view showing an intermediate stage of a branch connection method using the pipe joint of FIG.

11 is a front view showing a final stage of a branch connection method using the pipe joint of FIG.

FIG. 12 is a perspective view of a pipe joint according to still another embodiment of the present invention.

FIG. 13 is a side view showing a first stage of a conventional branch connection method.

FIG. 14 is a side view showing a second stage of a conventional branch connection method.

FIG. 15 is a side view showing a third stage of a conventional branch connection method.

FIG. 16 is a side view showing a final stage of a conventional branch connection method.

[Explanation of symbols]

11: Main pipe 13: Branch pipe 21: Pipe joint 23: Main pipe attachment part 25: Branch pipe connection part 27: Expanded part 29, 31: Heat-fusible resin layer 33: Ball valve

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Satoshi Okada 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (4)

[Claims] 1. A shape-memory resin molded body in which a saddle-shaped main pipe attachment portion to be attached to a plastic main pipe and a tubular branch pipe connection portion to connect the branch pipe are integrally formed, The pipe mounting part has a perimeter longer than the half circumference of the main outer peripheral surface, and has a saddle shape in which at least the hem is widened so as to straddle the main pipe. The shape is such that the inner surface of the main tube is held in close contact with the outer surface of the main tube by holding it, and the inner surface of the main tube mounting section is melted at the temperature at which the main tube mounting section is restored to the memorized shape. A plastic pipe branch connection pipe joint, characterized in that a heat-fusible resin layer that is fused to the outer surface of the main pipe is integrally provided. 2. The branch pipe connecting portion has a diametrically expanded portion into which a divergent pipe can be inserted, and the diametrically expanded portion has a cylindrical shape having an inner diameter equal to or smaller than the outer diameter of the branch pipe. The inner surface of the expanded portion is integrally provided with a heat-fusible resin layer that melts at the temperature at which the expanded shape is restored to the outer surface of the branch pipe. A pipe joint for branch connection of a plastic pipe according to claim 1. 3. The pipe joint for plastic pipe branch connection according to claim 1, wherein a ball valve is built in an intermediate portion of the branch pipe connection portion. 4. The main fitting part of the pipe joint according to claim 1, 2 or 3 is made to straddle a plastic main pipe, and then the main fitting part is heated to restore to a memorized shape and adheres to the main pipe. The heat-fusible resin layer on the inner surface is fused to the main pipe, and after making a hole in the main pipe in the branch pipe connecting portion, the branch pipe is connected to the branch pipe connecting portion. Plastic pipe branch connection method.