JP2007203725A - Circular resin tube joint and manufacturing process thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circular resin tube joint, which has a uniform wall thickness, highly circular, and bearing a waterproof material on the inner face of the tube. <P>SOLUTION: The resin tube joint is made by integrally molding the waterproof material on the inner face of the tube, wherein the resin tube joint is manufactured by closing a canopy-less outer mold 5 having a pair of respectively independent compression mechanisms 10 after closing a canopied outer mold 3 having a pair of respectively independent compression mechanisms 10 before compressing outer molds 3 and 5 while clutching an inner mold 7 with a parison and a waterproof cloth attached. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to the manufacture of a circular resin pipe joint used in the civil engineering field, the construction field, or the electric field, and more particularly to a circular resin pipe joint formed integrally with the inner surface of a circular resin pipe joint. .

Conventionally, resin pipes are widely used in civil engineering and construction fields such as water and sewage pipes, rainwater distribution pipes or electric pipes, and polyolefin resins such as polyethylene resins and propylene resins are used.
These circular resin pipes have a length of several meters to several tens of meters and serve to transmit water, electricity, light, or the like to a remote place connected using a connection joint called a resin pipe joint.
In this case, the resin pipe joint for connection is always water-stopped by using a water-stopping material (packing) to prevent water leakage or water intrusion.

The inventor previously proposed a resin pipe joint obtained by integrally molding a water-stopping material on the pipe inner surface in Japanese Patent Application No. 2001-309207.
This resin pipe joint is a method of integrally forming a water stop material on the inner surface of a pipe by a hot compression molding method rather than an expensive injection method, and has an advantage that it can be provided at low cost from a small diameter to a large diameter resin pipe joint. However, in this method, a resin pipe joint having a uniform thickness is obtained in the case of a small-diameter resin pipe joint. However, when the diameter is 150 mm or more, the thickness of the resin pipe joint tends to be non-uniform.
That is, when the heat compression molding is performed in a circular shape with the parison and the water stop material sandwiched between the outer mold and the inner mold on the two surfaces, the parison around the position where the left and right outer molds contact is difficult to be compressed. There was a tendency to become thinner.

In Japanese Patent Laid-Open No. 2003-251686, there is a method in which a moving member is provided in at least one of the pair of outer molds in order to make the wall thickness constant, and a circular shape is formed between the outer mold and the moving member to make it uniform. is suggesting.
However, since the moving direction of the moving member is not directed toward the center of the inner mold, the thickness uniformity of the resin pipe joint is insufficient.

Problems to be solved by the invention

  The present invention has been made in view of the above-described drawbacks, and provides a resin pipe joint that eliminates the aforementioned disadvantages. That is, an object of the present invention is to provide a resin pipe joint with a water blocking material having a uniform thickness.

Claim 1 provides a resin molding machine comprising an extrusion die for extruding at least a parison, four outer molds having independent compression mechanisms, and a circular inner mold located inside the four molds. And
After extruding the parison from the extrusion die as the first step, the inner mold formed by wrapping and fixing the parison and the water stop material located inside the parison is closed with a pair of outer molds having a canopy, and the remaining canopy as the second step Close the pair of molds that do not have 4 open molds as the third step,
The fourth step is a method for producing a circular resin pipe joint, which is formed by integrally forming a water stop material for removing a product from an inner mold on the inner surface of the pipe.
That is, this method is not the parison compression by the moving member provided auxiliary to at least one of the two outer dies or at least one of the two outer dies, but four having four independent compression structures. The parison is compressed and formed into a uniform circle with the outer mold.

  A second aspect is a circular resin pipe joint product compression-formed by the manufacturing method of the first aspect.

According to a third aspect of the present invention, there is provided a resin molding machine comprising at least an extrusion die for extruding the parison, four outer molds having independent compression mechanisms, and a circular inner mold located inside the four molds. After extruding the parison from the extrusion die as the first step, the inner mold formed by wrapping and fixing the parison and the water stop material located inside the parison is closed with a pair of outer molds having a canopy, and the remaining as the second step Close the pair of molds without the canopy, inject gas into the mold as the third step, and open the four molds as the fourth step,
The fifth step is a method for manufacturing a circular resin pipe joint, which is formed by integrally forming a water stop material for removing a product from an inner mold on the inner surface of the pipe.
After closing the four molds, by injecting gas from the inner mold or the like, it becomes easier to remove the product from the inner mold, and at the same time, the smoothness of the outer surface of the resin pipe joint can be improved. .
Even if the gas used here is air or N ₂ gas, the type of gas is not limited as long as it is not harmful.

  According to a fourth aspect of the present invention, there is provided a circular resin pipe joint product obtained by integrally molding a waterstop material compression-molded by the manufacturing method of the third aspect on the inner surface of the resin pipe.

Claim 5 defines the size of an outer mold having no canopy and an outer mold having a canopy, and A / B (specified in the later sentence) is in the range of 0.2 to 0.45. It is.
Next, the resin pipe joint with a water stop material of the present invention and the manufacturing method thereof will be described in more detail.
The resin pipe joint with a water stop material of the present invention is a resin pipe joint in which a water stop material is integrally formed on the inner surface of the pipe.
Here, the integral molding refers to the one that joins the water-stopping material at the same time as the molding of the resin pipe joint. Specifically, before the parison softening resin has adhesiveness when molding from the parison to the resin pipe joint. This means that the waterstop material is integrated with the parison.

In general, thermoplastic resin such as polyethylene resin, polypropylene resin, and vinyl chloride resin is used for the resin pipe joint of the present invention. However, the resin pipe joint is not limited to these resins, and has appropriate physical strength and durability as a resin pipe joint. Any thermoplastic resin may be used.
The resin pipe joint of the present invention includes not only a resin spiral pipe joint for connecting spiral pipes but also a circular resin pipe joint for connecting simple circular pipes without unevenness. Hereinafter, the resin spiral pipe joint will be described unless otherwise specified.

Next, the water stop material integrated into the resin spiral pipe joint of the present invention is rubber foam, polyurethane foam, polyolefin foam or water-swellable urethane foam / non-foam, water-swellable olefin, water-swellable rubber. Examples include foam / non-foam, water absorbent fiber nonwoven fabric, and hydrophobic fiber nonwoven fabric.
Polyurethane foam, polyolefin or rubber foam can be used regardless of whether they are closed cells or open cells, but open cells are preferred. This is because the resin spiral pipe joint is used as a female and the connection pipe is connected as a male pipe. However, when the connection pipe is screwed in a spiral shape, the open cell body is easily compressed and deformed, and can be easily twisted. . On the other hand, in the case of a closed cell body, it takes time to connect the closed cell body because it is difficult to be compressed and deformed. However, when the water-stopping material is a closed cell body, the connection purpose can be achieved by applying water or a lubricant such as a surfactant to the connecting pipe or the water-stopping material.

  The water-swellable waterstop material used in the present invention may be an open cell body, a closed cell body, or a non-foamed body. Since these water-swellable water-stopping materials swell in contact with water, they do not necessarily need to be sealed by the water-stopping material when the resin pipe joint is connected. This makes it easy to insert. When this water-swellable water-stopping material is used, a small amount of water enters or leaks from the gap between the packing and the connecting pipe immediately after the water comes, but immediately absorbs this water and swells to stop the water. It will be.

  As the polyolefin foam used in the present invention, a general-purpose polyethylene foam, a polypropylene foam, a hydrophobic foam such as a polyethylene propylene foam pair can be used, but water filled with a filler such as a water-absorbing resin is also used. Water-swellable olefin foams that swell by swell and non-foamable water-swellable olefins can also be used.

As the rubber foam used in the present invention, SBR rubber, EPDM rubber, CR rubber or the like can be used.
The rubber foam used in the present invention is not limited to a general-purpose closed cell body, but a water-swellable rubber foam filled with a water-absorbing resin as well as a polyolefin foam and a non-foamable water-swellable rubber can be used. .
Here, the water-absorbing resin may be polymerized and partially crosslinked electrolyte water-absorbing resin such as polyacrylic acid soda or non-electrolyte water-absorbing resin such as hydrophilic polyurethane and ultrahigh molecular weight polyethylene oxide.

  The polyurethane foam used in the present invention is a hydrophilic closed-cell polyurethane produced from a polyether such as a general-purpose polyoxyalkylene polyol or a general-purpose polyoxyalkylene glycol, a dicarboxylic acid polyester such as adipic acid and a polyisocyanate, and Polyol is hydrophobic, for example dimer acid polyester polyol made from dimer acid and glycol, polybutadiene polyol, hydrophobic closed cell polyurethane or hydrophobic open cell polyurethane made from polyisoprene polyol and polyisocyanate can be used. is there. Closed-cell or open-cell water-swellable polyurethane filled with so-called electrolyte-based water-absorbing resin that is polymerized and partially crosslinked, such as polyacrylic acid soda, and non-electrolyte-based water-absorbing resin such as hydrophilic polyurethane and ultrahigh molecular weight polyethylene oxide In addition, non-foaming water-swellable urethane can also be used.

The water-absorbing fiber used in the present invention refers to a water-absorbing swollen fiber that swells by absorbing water. In this case, water is stopped by sealing the gap between the fibers by swelling.
The hydrophobic fiber used in the present invention refers to polyethylene fiber, polypropylene fiber, polyethylene propylene fiber or the like, but is not limited thereto, and any hydrophobic fiber may be used.

The invention's effect

The circular resin pipe joint in which the water stop material is integrally molded on the inner surface of the pipe of the present invention has a uniform pipe thickness and thus has a high roundness after molding, and the round shape of the resin pipe joint even in the winter and summer seasons. Is not deformed, it is difficult to form a gap at the time of joint, and a high water-stopping property can be obtained.

Embodiments will be described below with reference to the drawings.
FIG. 1 is a side view of an image of an example facility for carrying out the present invention.
FIG. 2 is an image perspective view showing a state in which four outer molds are closed in the facility of FIG.
FIG. 3 is an image perspective view showing a state in which four outer molds are opened in the facility of FIG.
4 is an image perspective view showing the relationship between the parison 2 extruded from the extrusion die of the extruder in FIG. 1 and the inner mold 7 around which the water blocking material 11 is wound.
FIG. 5 is a cross-sectional view of the image when the parison 2 is pushed out to the outside of the inner mold in FIG.

The extrusion die that pushes out the parison from above is located above the equipment.
The water blocking material 11 is attached to the inner mold 7 over the entire circumference of the inner mold like a stocking. In this case, it is preferable that the water stop material 11 is in close contact with the inner mold.
The four outer molds 3, 4, 5 and 6 are arranged outside the inner mold, and the outer molds 3, 4, 5 and 6 are individually provided with hydraulic cylinders 10 and are free to move. Independently, the parison 1 can be compressed by sandwiching the inner mold.
The gas 8 is injected from the inner mold and is designed to be injected into the mold from the upper end portion 8b of the inner mold 7 through the gas pipe 8a.

  The parison 2 extruded from the extrusion die 1 is extruded to the outside of the inner mold 7 to which the water stop material 11 is attached. In this case, it is preferable that the parison 2 is extruded with a diameter larger by about 9 to 20 mm than the diameter of the water blocking material 11.

FIG. 6 is an image sectional view showing a state in which the parison is compressed from the left and right by the outer molds 3 and 4 having a pair of canopies.
FIG. 7 is an image sectional view showing a state in which the inner mold 7 is compressed by the outer molds 5 and 6 having no canopy.
FIG. 8 is an image side cross-sectional view showing a state compressed by the four outer molds 3, 4, 5, 6.

The parison extruded to the periphery of the inner mold 7 is first compressed by the outer molds 3 and 4 having a canopy, and then compressed by the outer molds 5 and 6 having no canopy.
It is preferable that the outer dies 5 and 6 are continuously compressed within 0.1 to 2.0 seconds after the outer dies 3 and 4 are compressed.
Both the outer mold and the inner mold are preliminarily supplied with cooling water, and the parison is cooled.
The gas is preferably injected immediately after the four outer molds are closed. Normally, gas is injected from the inner mold, but it may be injected from other parts. The gas to be injected may be air, N ₂ gas, or other gas, but a pressure of about 0.5 Mpa is preferable.

The injection of this gas has the effect of facilitating removal of the product from the inner mold even when the resin shrinks when the outer mold is opened. The gas can be injected from either the inner mold or the outer mold, but preferably from the inner mold. The inner mold has better product demolding properties and smooth product surface.
By injecting this gas, in the case of a spiral tube, the product can be easily removed from the inner mold while rotating. In the case of a circular tube without a spiral, a large force is required to pull out the product from the inner mold. In this case, the gas can be extracted with a small force by injecting it. Further, it is preferable that the product is removed from the inner mold before being cooled by the outside air and contracted.

In the case of a spiral tube, the outer mold that does not have a canopy is opened first, the pair of four outer molds that have the canopy are removed, the product with the inner mold is taken out, and then the product is in close contact It is preferable to hold the inner mold from the surface of the product with a jig and turn the inner mold to remove the product. Alternatively, a pair of four outer molds having a canopy may be opened first, or the product with the inner mold may not be taken out, and the product may be rotated and removed as it is.
A small burr generated at the joint of the four molds works to prevent slipping when the product is held with a jig and the inner mold is turned. The inner mold may be turned by hand, or the rotation of a motor may be used.

  FIG. 9 is a diagram showing the relationship between the sizes of the outer molds 3, 4, 5, and 6. As shown in FIG. The ratio A / B between the mold width without the canopy and the mold width with the canopy is preferably in the range of 0.2 to 0.45, more preferably in the range of 0.25 to 0.4. If A / B is less than 0.2, the uniformity of the tube thickness is reduced, and even if it is greater than 0.45, the uniformity is not improved and the hydraulic pressure increases and the cost increases. .

  FIG. 10 is a layout view of a conventionally proposed resin pipe joint mold. The outer mold consists of two molds 3 'and 4'. Since the moving members 4a and 4'b are provided as a part of the 3'4 'mold, the arc centers of the 4'a and 4'b are not directed toward the center of the inner mold. For this reason, there is a defect that the contact position with the outer molds 3 ′ and 4 ′ is difficult to have a uniform thickness.

FIG. 11 is a cross-sectional view showing a state in which two spiral pipes are joined with the spiral resin pipe joint of the present invention.
The water stop material 11 is interposed between the spiral pipes 15 and 15 ′ and the spiral resin pipe joint 16 to swell, thereby stopping water.
In particular, in the case of a type in which the water-stopping material absorbs water and swells, even if a gap is formed, the flowing water is absorbed and swollen to completely stop water leakage.

The image side view of the installation for implementing this invention. FIG. 2 is an image perspective view showing a state where four outer molds are closed in the facility of FIG. 1. FIG. 2 is an image perspective view of a state where four outer molds are opened in the facility of FIG. 1. The image perspective view which shows the relationship between the parison extruded from the extrusion die in FIG. 1, and the inner metal mold | die which set the water stop material. Cross-sectional image of the parison 2 pushed out of the inner mold wrapped with a water-stopping material An image sectional view showing the state where a pair of outer metallic molds which have a canopy were closed. Furthermore, image sectional drawing which shows the state which closed a pair of outer metal mold | die which does not have a canopy. FIG. 8 is a side cross-sectional view of the image of FIG. 7 in the process of carrying out the present invention. Sectional drawing which shows the relationship between the magnitude | size of the outer metal mold | die which has a canopy, and the outer metal mold | die which does not have a canopy. The image sectional view showing the state of the external mold of the conventional method. Sectional drawing which shows the state which joined the spiral pipe | tube with the circular resin pipe joint of this invention.

Brief description of symbols

DESCRIPTION OF SYMBOLS 1 Extrusion die | dye 2 Parison 3 Outer metal mold | die 3 'which has the canopy of this invention Conventional outer metal mold | die 4' Outer metal mold | die 4 'which has the canopy of this invention Conventional type outer mold | die 4'a Movement of the outer metal mold | die 4 Member 4'b Moving member 5 of outer mold 4 Outer mold 6 without canopy of the present invention Outer mold 7 without canopy Inner mold 8 Gas hose 8a Gas pipe 8b Gas pipe end 9 Inner mold Base 10 Hydraulic machine 11 Water-absorbing swelling fiber 12 3, burr of joint of outer mold 13 Cooling water 14 Mold plate 15 Spiral pipe 16 Spiral resin pipe joint of the present invention

Claims (5)

First, there is prepared a resin molding machine comprising at least an extrusion die for extruding a parison, four outer molds having independent compression mechanisms, and a circular inner mold located inside the four molds. After extruding the parison from the extrusion head as a process, the inner mold formed by wrapping and fixing the parison and the water stop material located inside the parison is closed with a pair of outer molds having a canopy,
Close the pair of molds without the remaining canopy as the second step,
Open the outer mold as the third step,
As a fourth step, a method for manufacturing a circular resin pipe joint, which is formed by integrally forming a water stop material for removing a product from an inner mold on the inner surface of the pipe. First, there is prepared a resin molding machine comprising at least an extrusion die for extruding a parison, four outer molds having independent compression mechanisms, and a circular inner mold located inside the four molds. After extruding the parison from the extrusion head as a process, the inner mold formed by wrapping and fixing the parison and the water stop material located inside the parison is closed with a pair of outer molds having a canopy,
Close the pair of molds without the remaining canopy as the second step,
Open the outer mold as the third step,
Circular resin pipe joint formed by integrally forming a water stop material that removes the product from the inner mold as the fourth step on the inner surface of the pipe. First, there is prepared a resin molding machine comprising at least an extrusion die for extruding a parison, four outer molds having independent compression mechanisms, and a circular inner mold located inside the four molds. After extruding the parison from the extrusion head as a process, the inner mold formed by wrapping and fixing the parison and the water stop material located inside the parison is closed with a pair of outer molds having a canopy,
Close the pair of molds without the remaining canopy as the second step,
As a third step, gas is injected into the mold,
4 outer molds are opened as the fourth process,
As a fifth step, a method for producing a circular resin pipe joint, in which a water-stopping material for removing a product from an inner mold is integrally formed on the inner surface of the pipe. First, there is prepared a resin molding machine comprising at least an extrusion die for extruding a parison, four outer molds having independent compression mechanisms, and a circular inner mold located inside the four molds. After extruding the parison from the extrusion head as a process, the inner mold formed by wrapping and fixing the parison and the water stop material located inside the parison is closed with a pair of outer molds having a canopy,
Close the pair of molds without the remaining canopy as the second step,
As a third step, gas is injected into the mold from the inner mold,
4 outer molds are opened as the fourth process,
A circular resin pipe joint formed by integrally molding a water-stopping material that removes the product from the inner mold as a fifth step and opens the four outer molds to remove the product. The method for producing a circular resin joint according to claim 1 or 3, wherein a ratio of an outer mold width not having a canopy and an outer mold width having a canopy is in a range of 0.2 to 0.45.

Images