JP6797013B2 - Water supply and drainage pipes and their manufacturing methods - Google Patents

Description

The present invention relates to a water supply / drainage pipe and a method for manufacturing a water supply / drainage pipe, which are easy to construct.

Since polyethylene pipes are excellent in corrosion resistance and flexibility, they are used in the field of water supply and drainage instead of metal pipes and vinyl chloride pipes. Water tanks are installed in condominiums and other condominiums and large commercial facilities, and the water stored in the water tanks is used for water supply and drainage. If the water in the water tank is used, the water pressure and temperature at the time of water supply and drainage can be controlled, so the water supply and drainage pipes are not required to have the same performance (heat resistance, pressure resistance, etc.) as those for general houses. In recent years, due to a shortage of craftsmen and shortening of construction time, there is an increasing demand for inexpensive and easy-to-construct water supply and drainage pipes. Generally, in the polyethylene pipe used in the field of water supply and drainage, the inner layer portion in contact with water or the like to be circulated inside is made of highly durable polyethylene. Further, in order to compensate for the weakness of the polyethylene pipe, the outer layer portion is covered with a resin having a predetermined function to form the outer layer portion (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2004-225821

It has been proposed that the polyethylene pipe described above be configured to facilitate construction by providing a connecting portion having a necessary shape such as a flange at the end portion for connection with the joint. In a pipe having a configuration as in Patent Document 1, if a connecting portion is formed around the outer layer portion by injection molding, water may leak from between the inner layer portion and the outer layer portion. Further, in the pipe having the structure as in Patent Document 1, the polyethylene pipe forming the inner layer portion has high rigidity, and the pipe cannot be easily bent. Therefore, in order to change the direction of the pipe, it is necessary to measure the floor plan, cut the pipe according to the measured floor plan, and then connect the pipe to the joint, which requires specialization and time for construction.

That is, the present invention has been proposed in view of the above-mentioned problems related to the prior art, and provides a water supply / drainage pipe having excellent workability and high liquidtightness, and a method for manufacturing the same. The purpose is to do.

In order to overcome the above-mentioned problems and achieve the intended purpose, the water supply / drainage pipe of the invention according to claim 1 of the present application is used.
With a flexible pipe body,
The end of the pipe body is provided by injection molding and is provided with a joint and a connectable portion.
The pipe body
The inner layer made of polyethylene and
It is made of a resin that is more flexible than the polyethylene forming the inner layer portion, and has an outer layer portion that covers the outer peripheral surface of the inner layer portion and is thicker than the wall thickness of the inner layer portion .
The gist is that the connecting portion is made of polyethylene, and the inner peripheral surface is welded to the outer peripheral surface of the inner layer portion and the end surface of the inner layer portion is welded by the injection molding .
According to the invention of claim 1, it can be easily connected to the joint by the connecting portion provided at the end, and the flexible pipe body can be deformed by bending or the like, so that the construction is easy. Can be done. Further, since the inner peripheral surface of the connecting portion and the outer peripheral surface of the inner layer portion are directly welded, even if the connecting portion is provided at the end portion of the pipe body, the liquidtightness of the end portion can be maintained.
Further, since the wall thickness of the outer layer portion is thicker than the wall thickness of the inner layer portion, buckling of the inner layer portion can be more appropriately prevented when the pipe body is deformed by bending or the like.

The gist of the invention according to claim 2 is that the inner peripheral surface of the inner layer portion constituting the flow path and the inner peripheral surface of the connecting portion are aligned without a step .

The gist of the invention according to claim 3 is that the pipe body is provided with a recess in which the outer layer portion is recessed inward in the radial direction in the vicinity of the connection portion .
According to the invention of claim 3, the recess provided in the vicinity of the connecting portion makes it difficult to slip when connecting the connecting portion to the joint.

In order to overcome the above-mentioned problems and achieve the intended purpose, the method for manufacturing a water supply / drainage pipe according to claim 4 of the present application is described.
A pipe body made of an inner layer portion made of polyethylene and a resin made of a resin more flexible than the polyethylene forming the inner layer portion and having an outer layer portion covering the outer peripheral surface of the inner layer portion, and a connecting portion provided at an end portion of the pipe body. It is a manufacturing method of water supply and drainage pipes equipped with
A core having an outer diameter matching the inner flow path of the inner layer portion is inserted from the end of the pipe body.
The end of the pipe body with the inner layer exposed is set in a molding mold that defines a cavity that matches the connection to be obtained.
The pipe inserted into the cavity by filling the cavity with a polyethylene material while supporting the end of the inner layer portion facing the cavity from the inside with the core from the end to the entire end. By molding the connecting portion around the outer peripheral surface of the inner layer portion exposed at the end of the main body, the inner peripheral surface of the connecting portion is welded to the outer peripheral surface of the inner layer portion, and the flexible portion is provided. The gist is to provide the connection portion at the end of the pipe body.
According to the invention of claim 4, since the connecting portion is formed around the end portion of the pipe body in which the inner layer portion is exposed, the inner peripheral surface of the connecting portion and the outer peripheral surface of the inner layer portion can be welded. The obtained water supply / drainage pipe can be easily connected to the joint by the connecting portion provided at the end, and the flexible pipe body can be deformed by bending or the like, so that the construction can be easily performed. be able to. Further, in the obtained water supply / drainage pipe, the inner peripheral surface of the connecting portion and the outer peripheral surface of the inner layer portion are directly welded, so that even if the connecting portion is provided at the end of the pipe body, the end is liquidtight. You can keep your sex.

In the invention according to claim 5, the outer layer portion is compressed by a convex shape provided in the molding die at a portion of the pipe body that is supported by the core from the inside in the vicinity of the end inserted into the cavity. The gist is that the connection portion is injection-molded by being sandwiched so as to be used.
According to the fifth aspect of the present invention, since the vicinity of the end portion to be inserted into the cavity in the pipe main body is sandwiched by the molding mold, it is possible to prevent the pipe main body from being displaced during injection molding of the connecting portion.

According to the water supply / drainage pipe according to the present invention, it is possible to have excellent workability and improve the liquidtightness of the end portion provided with the connecting portion. According to the method for manufacturing a water supply / drainage pipe according to the present invention, a water supply / drainage pipe having a high liquidtightness at an end provided with a connecting portion and having excellent workability can be easily obtained.

It is a schematic perspective view which shows the pipe which concerns on a preferred embodiment of this invention. It is sectional drawing which shows the main part of the pipe of an Example. It is explanatory drawing which shows the manufacturing process of the pipe of an Example. It is explanatory drawing which shows the manufacturing process of the pipe of an Example.

Next, a water supply / drainage pipe (hereinafter referred to as a pipe) and a method for manufacturing the pipe according to the present invention will be described below with reference to the accompanying drawings with reference to suitable examples.

As shown in FIGS. 1 and 2, the pipe 10 according to the embodiment includes a cylindrical pipe body 12 that defines a flow path 10a through which a medium such as water can flow, and an end portion of the pipe body 12. It is provided with a connecting portion 14 which is provided in the above and is configured to be connectable to a joint (not shown) connecting the pipes 10 and 10. As a whole, the pipe body 12 has flexibility that can be deformed at the time of construction, such as bending or returning from a curved state to a straight state. The pipe 10 may have a configuration in which connecting portions 14 are provided at both ends of the pipe main body 12, or a configuration in which the connecting portions 14 are provided only at one end of the pipe main body 12.

As shown in FIGS. 1 and 2, the pipe main body 12 is provided so as to define the flow path 10a and cover the inner layer portion 16 in contact with the medium flowing through the flow path 10a and the outside of the inner layer portion 16. , A multi-layer structure including an outer layer portion 18 forming an outer surface of the pipe 10. The inner layer portion 16 is made of polyethylene and has flexibility that can be bent at the time of construction or deformed from a curved state to a linear state. As the polyethylene constituting the inner layer portion 16, for example, high heat resistant polyethylene (PE-RT), cross-linked polyethylene (PE-X), high density polyethylene (PE-HD) and the like can be used. Among these, highly heat-resistant polyethylene is preferable as the inner layer portion 16 because it has high heat resistance, the wall thickness of the inner layer portion 16 itself can be made thinner, and welding with the connecting portion 14 is easy. The outer layer portion 18 is made of a resin that is more flexible than the resin constituting the inner layer portion 16, and for example, an ethylene vinyl acetate copolymer (EVA), a thermoplastic elastomer such as an olefin-based thermoplastic elastomer (TPO), or the like is used. be able to. The ethylene-vinyl acetate copolymer is preferable as the outer layer portion 18 because it can contribute to the improvement of workability and can particularly reduce the cost.

In the pipe 10, the outer layer portion 18 has a main function of protecting the inner layer portion 16 having flexibility and preventing buckling of the inner layer portion 16 when the pipe body 12 is bent. For the pipe body 12, it is preferable to set the wall thickness of the outer layer portion 18 to be thicker than the wall thickness of the inner layer portion 16 from the viewpoint of protecting the inner layer portion 16 and preventing buckling, and in particular, setting the thickness of the outer layer portion 18 to the inner layer. It is desirable to set the thickness in the range of 1.2 to 10 times the thickness of the portion 16. In the pipe main body 12, the relatively hard inner layer portion 16 is made thin and the relatively soft outer layer portion 18 is made thick, so that even if the pipe main body 12 is bent at the time of construction, it is difficult to buckle.

The connecting portion 14 is made of a thermoplastic resin that can be welded to the inner layer portion 16, and is a resin molded product made of polyethylene in the same manner as the inner layer portion 16 in the examples. As the polyethylene constituting the connecting portion 14, for example, high heat resistant polyethylene (PE-RT), high density polyethylene (PE-HD) and the like can be used, and a polyethylene material different from that of the inner layer portion 16 may be used. .. As shown in FIGS. 1 and 2, the connecting portion 14 is formed in a cylindrical shape having a diameter larger than that of the pipe body 12, and in the embodiment, the flange 14a extending in the radial direction is inserted into an end opposite to the insertion end. Be prepared for. At the end of the connecting portion 14, the inner peripheral surface of the connecting portion 14 is welded to the outer peripheral surface of the inner layer portion 16. Further, the connecting portion 14 is provided so as to cover the end surface 16a of the inner layer portion 16, and is also welded to the end surface 16a of the inner layer portion 16.

As shown in FIGS. 1 and 2, the pipe 10 is formed with a recess 20 in the vicinity of the connecting portion 14 in the pipe body 12. The recess 20 is formed so that the outer layer portion 18 is recessed inward in the radial direction and extends in an annular shape around the outer layer portion 18. In the embodiment, the plurality of recesses 20 are arranged apart from each other in the axial direction of the pipe body 12.

Next, a method of manufacturing the pipe 10 according to the embodiment will be described. First, a pipe body 12 having a two-layer structure having an inner layer portion 16 made of polyethylene and an outer layer portion 18 made of a resin more flexible than the inner layer portion 16 is prepared (FIG. 3A). The pipe body 12 can be obtained by extrusion molding or the like. The outer layer portion 18 at the end of the pipe body 12 is peeled off over the range where the connecting portion 14 is provided to expose the inner layer portion 16 at the end (FIG. 3 (b)). A core 22 having an outer diameter matching the flow path 10a is fitted inside the end portion of the pipe body 12. Here, the core 22 extends not only to the portion where the connecting portion 14 is provided, but also to the portion where the pipe main body 12 is sandwiched by the molding die 24 (FIG. 4) for forming the connecting portion 14. Placed inside.

Next, the end portion of the pipe body 12 with the inner layer portion 16 exposed is set in the molding die 24 that defines the cavity 26 that matches the connection portion 14 to be obtained (FIG. 4A). The molding die 24 is closed, and the end portion of the pipe body 12 with the inner layer portion 16 exposed is arranged inside the cavity 26. Further, when the molding die 24 is closed, the vicinity of the forming portion of the connecting portion 14 at the end portion of the pipe main body 12 (near the end portion inserted into the cavity 26 in the pipe main body 12, hereinafter simply referred to as a near portion) is formed in the molding die. Hold by 24. At this time, the vicinity portion of the pipe body 12 is sandwiched by the molding die 24 so as to compress the outer layer portion 18 inward in the radial direction, and the pipe body 12 is fixed so as not to move. In the embodiment, the sandwiched portion of the pipe body 12 in the molding die 24 has a convex shape 28, and the convex shape 28 bites into the outer layer portion 18 of the vicinity portion.

Next, the cavity 26 is filled with a polyethylene material to be the connecting portion 14, and the connecting portion 14 is formed around the outer peripheral surface of the inner layer portion 16 exposed at the end of the pipe body 12 inserted into the cavity 26 (FIG. 4). (b)). By inserting the inner layer portion 16 into the cavity 26 and injection molding in this way, the inner peripheral surface of the connecting portion 14 and the outer peripheral surface of the inner layer portion 16 are welded, and the connecting portion 14 is attached to the end portion of the pipe body 12. It is fixed (Fig. 4 (c)). Here, the connecting portion 14 of the embodiment is formed so as to cover the end surface 16a of the inner layer portion 16 and is also welded to the end surface 16a. Then, in the pipe 10 from which the connecting portion 14 is formed and taken out from the molding die 24, a recess 20 derived from the sandwiching of the molding die 24 is formed in the vicinity portion.

Since the pipe 10 is provided with a connecting portion 14 at the end portion, the pipe 10 can be easily connected to the joint without requiring scraping work of the outer surface of the pipe body 12 and subsequent cleaning work. .. Further, since the pipe body 12 can be deformed by bending or the like, it is possible to pipe the pipe by an appropriate route according to the situation at the site without performing processing such as cutting at the time of construction. As described above, the pipe 10 can be easily constructed and has excellent workability. Since the pipe 10 is not the outer layer portion 18 but the outer peripheral surface of the inner layer portion 16 made of polyethylene and the inner peripheral surface of the connecting portion 14 made of polyethylene are directly welded, the pipe 10 is between the pipe body 12 and the connecting portion 14. It is possible to prevent the liquid flowing through the flow path 10a from leaking out. Further, since the connecting portion 14 is provided so as to cover the end surface 16a of the inner layer portion 16 and is welded to the end surface 16a, the pipe 10 can more reliably prevent the leakage of the liquid. As described above, according to the pipe 10 of the embodiment, even if the connecting portion 14 is provided at the end portion of the pipe main body 12, the liquidtightness of the end portion can be maintained.

As described above, the connection is welded to the outer peripheral surface of the inner layer portion 16 by a simple process of inserting the end portion of the pipe body 12 with the inner layer portion 16 exposed into the cavity 26 and injection molding the connection portion 14. A pipe 10 having a portion 14 can be obtained. Further, since the connecting portion 14 is formed around the inner layer portion 16, there is no gap between the connecting portion 14 and the inner layer portion 16, and the connecting portion 14 can be appropriately welded to the inner layer portion 16. Further, since the connecting portion 14 is not provided around the outer layer portion 18, it is possible to suppress the influence of heat on the outer layer portion 18 when the connecting portion 14 is formed. Therefore, the obtained pipe 10 can prevent the liquid flowing through the flow path 10a from leaking through between the pipe main body 12 and the connecting portion 14, and the connecting portion 14 is provided at the end of the pipe main body 12. However, the liquidtightness of the end portion can be maintained.

According to the manufacturing method described above, since the nearby portion of the pipe body 12 is sandwiched by the molding die 24, it is possible to prevent the pipe body 12 from being displaced during injection molding of the connecting portion 14. Moreover, since the outer layer portion 18 is sandwiched by the convex shape 28 of the molding die 24 so as to be compressed by utilizing the flexibility of the outer layer portion 18, the pipe body 12 can be held more reliably. Further, the injection pressure at the time of injection molding of the connecting portion 14 can be increased so that the connecting portion 14 and the outer layer portion 18 can be welded more reliably. Then, in the obtained pipe 10, the recess 20 remaining in the vicinity of the connecting portion 14 becomes a non-slip when connecting the connecting portion 14 to the joint, so that the connection work to the joint can be facilitated.

According to the manufacturing method described above, since the portion of the pipe body 12 to which the connecting portion 14 is injection-molded is supported from the inside by the core 22, the flexible inner layer portion 16 is prevented from being deformed and connected. The portion 14 can be formed appropriately. Further, since the portion of the pipe body 12 sandwiched by the molding die 24 is supported from the inside by the core 22, deformation of the pipe body 12 can be prevented.

(Change example)
Not limited to the above-described embodiment, it can be changed as follows, for example.
(1) In the embodiment, the pipe body having a two-layer structure is mentioned, but the present invention is not limited to this, and a layer different from the inner layer portion and the outer layer portion is provided, such as providing an intermediate layer between the inner layer portion and the outer layer portion. It may have three or more layers.
(2) The presence / absence, number, shape, etc. of recesses provided in the vicinity of the connection portion in the pipe body are not limited to the examples.

12 Pipe body, 14 Connections, 16 Inner layer, 18 Outer layer, 20 Recesses,
24 Mold, 26 Cavity

Claims (5)

With a flexible pipe body,
The end of the pipe body is provided by injection molding and is provided with a joint and a connectable portion.
The pipe body
The inner layer made of polyethylene and
It is made of a resin that is more flexible than the polyethylene forming the inner layer portion, and has an outer layer portion that covers the outer peripheral surface of the inner layer portion and is thicker than the wall thickness of the inner layer portion .
The connection portion is made of polyethylene, and the water supply / drainage pipe is characterized in that the inner peripheral surface is welded to the outer peripheral surface of the inner layer portion and the end surface of the inner layer portion is welded by the injection molding . The water supply / drainage pipe according to claim 1 , wherein the inner peripheral surface of the inner layer portion constituting the flow path and the inner peripheral surface of the connecting portion are aligned without a step . The water supply / drainage pipe according to claim 1 or 2 , wherein the pipe body is provided with a recess in which the outer layer portion is recessed inward in the radial direction in the vicinity of the connection portion . A pipe body made of an inner layer portion made of polyethylene and a resin made of a resin more flexible than the polyethylene forming the inner layer portion and having an outer layer portion covering the outer peripheral surface of the inner layer portion, and a connecting portion provided at an end portion of the pipe body. It is a manufacturing method of water supply and drainage pipes equipped with
A core having an outer diameter matching the inner flow path of the inner layer portion is inserted from the end of the pipe body.
The end of the pipe body with the inner layer exposed is set in a molding mold that defines a cavity that matches the connection to be obtained.
The pipe is filled with a polyethylene material and inserted into the cavity while the end of the inner layer portion facing the cavity is supported from the inside by the core from the end to the entire end. By molding the connection portion around the outer peripheral surface of the inner layer portion exposed at the end portion of the main body, the inner peripheral surface of the connection portion is welded to the outer peripheral surface of the inner layer portion, and the flexible portion is provided. A method for manufacturing a water supply / drainage pipe, which comprises providing the connection portion at an end portion of the pipe body. The portion of the pipe body near the end inserted into the cavity, which is supported by the core from the inside , is sandwiched by the convex shape provided in the molding die so as to compress the outer layer portion. The method for manufacturing a water supply / drainage pipe according to claim 4, wherein the connection portion is injection-molded.

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