JP3268584B2 - Pipe fitting and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint in which a ring-shaped rubber packing is provided on the inner surface of a joint body made of fiber- reinforced synthetic resin.
The present invention relates to a hand manufacturing method .

[0002]

2. Description of the Related Art For example, a buried pipe for sewage or agricultural water is a composite pipe comprising a fiber reinforced synthetic resin (FRP) layer and a resin mortar layer (hereinafter referred to as "FRPM pipe").
In many cases, a pipe joint in which a rubber packing is provided on the inner surface of a joint body made of FRP (including FRPM, the same applies hereinafter) is used as a pipe connecting means.

In this type of pipe joint, it is extremely important to increase the bonding strength of the rubber packing to the FRP joint body for sealing against a high internal pressure fluid.

Therefore, various techniques have been conventionally proposed in order to enhance the coupling between the joint body (or the pipe connected to the joint) and the packing.

[0005] As such a technique, for example, the surface shape of a joint body and a rubber packing corresponding to each other is devised, and these parts are fitted and bonded (Japanese Patent Laid-Open No. 52-107621). ), A mat made of an arbitrary fiber is bonded to the inner surface of a cylindrical rubber to form a packing, and the inner mat and the pipe are bonded with an adhesive during the packing (Japanese Utility Model Publication No. 49-26747). JP-A-53-4), a band formed by impregnating a glass fiber with a resin and directly forming a band on the surface of rubber to cure the band.
No. 9325).

As a method of integrally molding a rubber and a resin such as polyester or epoxy, a technique of blending a liquid resin with an isocyanate in an amount of about 50 to 100 PHR to bond them firmly has been known.

[0007]

However, the structure disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 52-107621 has no adhesive force itself, although the surface shape of the rubber packing or the like is devised. If the tube is inserted at an angle, the rubber packing may come off. Although the effect is certainly obtained by bonding with an adhesive, if the curing of the adhesive is not reliable or there is a shortage of the adhesive, the rubber packing may come off during the bonding operation. Further, since the rubber packing must be quickly bonded before the adhesive is applied and then cured, the operation requires skill.

[0008] Further, in Japanese Patent Publication No. 49-26747, a mat made of fiber and an adhesive are indispensable, and the number of steps is increased by the amount of bonding work (this point is described in the above-mentioned Japanese Patent Laid-Open Publication No. The same applies to the case of Japanese Patent Laid-Open Publication No. 52-107621), which leads to higher costs.

On the other hand, the one described in Japanese Patent Application Laid-Open No. 53-49325 does not require a mat or an adhesive between the joint body and the rubber packing, and has a configuration in which both are integrally formed. The number of processes is smaller than the above two,
There is an advantage that the cost is low. However, even if the liquid resin is directly supplied to the surface of the rubber and molded and cured, there is a disadvantage that the two do not adhere to each other.

Incidentally, the conventionally known method of integrally molding a liquid resin with isocyanate and compounding it with rubber involves a large amount of isocyanate, so that the cost is high and the physical properties of the resin are changed by the large amount of isocyanate. However, in most cases, there is a disadvantage that the tensile strength, hardness, elastic modulus and the like are reduced. As a result, this method is not widely used in practice.

The present invention addresses such a situation, and as a pipe joint in which a ring-shaped rubber packing is provided on the inner surface of a FRP joint body, the work of attaching rubber packing to the inner surface of the joint body can be facilitated. It is an object of the present invention to provide a method of manufacturing a pipe joint which can be manufactured at low cost and in which a rubber packing is firmly and integrally formed on the inner surface of the joint body.

[0012]

In order to achieve the above object, the present invention is characterized in that it is configured as follows.

That is, in the method for manufacturing a pipe joint according to the first aspect , a ring-shaped rubber is provided on an inner surface of a fiber-reinforced synthetic resin joint body.
Packing is provided, and the main body and packing are
In the method of manufacturing pipe joints bonded via cyanate
In addition , a ring-shaped rubber packing is arranged on a predetermined outer peripheral surface of a cylindrical mold that is made expandable and contractible, and the diameter of the cylindrical mold is increased, so that the ring-shaped rubber packing has tension. The ring-shaped rubber packing is mounted on a cylindrical mold, and an isocyanate compound is applied to the outer peripheral surface of the ring-shaped rubber packing. Then, a thermosetting resin liquid is applied to the outer peripheral surface of the ring-shaped rubber packing and the cylindrical mold. After forming an uncured molding material layer composed of the resin and the reinforcing fibers, and curing the molding material layer, the diameter of the cylindrical mold is reduced and the mold is released.

Further, the manufacturing method of the pipe joint of claim 2, wherein, in the above-described manufacturing method, a ring-shaped rubber packing, to close the gap formed in the mounting surface of the said ring-shaped rubber packing and the cylindrical mold The projections made as described above are provided to prevent the thermosetting resin liquid and the reinforcing fibers from entering the mounting surface from the outer periphery of the ring-shaped rubber packing and the cylindrical mold.

The rubber constituting the rubber packing includes:
Not only natural rubber but also styrene-butadiene rubber (SB
R), ethylene-propylene-diene rubber (EPD)
M), chloroprene rubber (CR) and other synthetic rubbers may be used without particular limitation.

It is preferable that the isocyanate is diluted with a volatile solvent in an amount of 50% by weight or more and that the content of the isocyanate group (-NCO) in a diluted state is 5% or more. This is because if the isocyanate (solid content) is 50% by weight or more, it becomes unnecessarily thick when applied on rubber, and it is not preferable because the cost is high, and the isocyanate group content is 5%. If the amount is less than the above, a sufficient adhesive strength cannot be obtained between the rubber packing and the FRP due to an insufficient isocyanate group.

[0017] It should be noted, as an example of a volatile solvent referred to herein is,
Examples include ethyl acetate, methylene chloride, xylene, and butyl acetate.

As a method for applying this isocyanate,
It can be applied by a paintbrush, brush, spray or the like.

Furthermore, as the thermosetting resin, for example, epoxy resin, unsaturated polyester resins, allyl resins, cross-linked resin such as an acrylic resin. If necessary, a curing agent such as peroxide and an accelerator such as cobalt naphthenate may be added to the thermosetting resin.

Further, as the reinforcing fibers, for example, using a glass roving can this glass chop or mat, sand, also be used in combination with calcium carbonate.

[0021]

According to the above construction, since the FRP joint body and the ring-shaped rubber packing provided on the inner surface thereof are bonded via the isocyanate, the joint body is near the interface between the joint body and the packing. Hydroxyl groups and isocyanate existing in the synthetic resin on the main body side react with each other and are strongly bonded to each other.

On the other hand, in the other synthetic resin portion, i.e. FRP portion excluding the vicinity of the interface, for curing by the curing agent without the influence of the isocyanate, it is not to cause changes in physical properties such as reduced tensile strength.

Furthermore, according to the manufacturing method of the pipe joint of claim 2, wherein, the projections, the thermosetting resin solution and reinforcing fibers from the outer peripheral portion to the mounting surface of the ring-shaped rubber packing and the cylindrical mold intrusion Therefore, a pipe joint to which the thermosetting resin liquid and the reinforcing fiber unnecessary for the ring-shaped rubber packing do not adhere is manufactured.

[0024]

Embodiments of the present invention will be described below. (First Embodiment) FIG. 1 relates to a pipe joint for a buried pipe manufactured by an example of the manufacturing method of the present invention .

[0025] First, to explain this pipe joint, the tube fitting 1, as shown in the figure, the FRP-made joint body 2,
It has ring-shaped rubber packings 3, 3 provided on inner surfaces 2a, 2a at both ends thereof.

[0026] Each ring rubber packing 3, in this embodiment be made of SBR, as shown enlarged in FIG. 2,
One end is provided with a rib 3a and the other end is sealed with an insertion tube (not shown).
b is formed.

[0027] Then, as a characteristic portion, both end portions the inner surface 2a of the joint body 2, the outer surface 3c of 2a and the rubber packing 3,3, and a 3c are bonded via an isocyanate 4,4.

[0028] The pipe joint 1, the production of following the present invention
It was manufactured by an example of the method .

[0029] First, as shown in FIG. 3, a cylindrical mold (outer diameter of 900 mm) attached 10 to the ring-shaped rubber packing (see Figure 1) 3,3 in a state where appropriate have tension I do.

As shown in FIG. 4, the entire mold 10 is divided into a first to a fourth plurality of molded portions 11 to 14, and a pair of opposed first and fourth molded portions 11 to 14 are formed. The second forming portions 11 and 12 are connected to the third forming portion 13 via hinges 15 respectively. The cross-shaped cylinder 16 provided in the mold 10 allows the first and second forming parts 11 and 12 and the fourth forming part 14 to move in the radial direction, thereby reducing the diameter as a whole. And the diameter can be freely expanded. Therefore, with the diameter of the mold 10 reduced,
By mounting the rubber packings 3 and 3 on the outer surface and then expanding the diameter, the packings 3 and 3 can be mounted in a state where the packings are provided as described above.

[0031] Next, in this state, the rubber packing 3,3
Isocyanate (Desmodur R, manufactured by Bayer AG: solid content 2)
(0% by weight methylene chloride solution, isocyanate group content: 7.0 ± 0.2%). With this application, the solvent was quickly evaporated from the application surface, and a thin isocyanate film (with stickiness) was formed.

Next, the molded tubular body by supplying an unsaturated polyester resin and glass roving and chopped on an outer peripheral portion of the die 10. In this case, the unsaturated polyester resin was added with 1 pHR of methyl ethyl ketone peroxide as a curing agent and 0.1 pHR of a cobalt naphthenate solution as an accelerator. The glass roving used was 2400 count.

[0033] Then, after curing by heating 10 minutes the tubular body by a heater and demolded by reducing the diameter of the mold 10. Thereby, the pipe joint 1 of FIG. 1 was obtained. In addition, this pipe joint 1
The thickness of the parallel portion 2b was 9 mm at the parallel portion.

In the pipe joint 1 thus obtained, F
Since the RP joint body 2 and the ring-shaped rubber packings 3, 3 attached to the inner surfaces 2a, 2a of both ends thereof are adhered via the isocyanate 4, 4, the interface between the joint body 2 and the packing 3, 3 is provided. In the vicinity, the joint body 2
Hydroxyl group and isocyanate 4,4
React with each other to be firmly bonded to each other.

On the other hand, in the other synthetic resin portion, i.e. FRP portion excluding the vicinity of the interface, for curing by the curing agent without the influence of the isocyanate 4,4, will not occur change in physical properties such as reduction of tensile strength .

[0036] For this pipe joint 1, rubber packing 3
A peel test was conducted to check the adhesive strength between the FRP portion and the FRP portion (both ends of the joint body 2). As shown in FIG. 5, this test was performed by pulling the rubber packing 3 from the inner surface 2a of the FRP joint body 2 in the angle direction A of 90 ° as much as possible, but the result was that the rubber packing 3 could not withstand, It has been torn. Thereby, it was confirmed that the rubber packing 3 was firmly adhered to the inner surface 2a of the FRP joint body 2.

[0037] In addition, the rubber tensile strength of this case 200
kg / cm ^2, the peeling strength was 20.0 kg / cm ^2. (Second Embodiment) In this embodiment , unlike the one manufactured in the first embodiment, a ring-shaped rubber packing 33 having irregularities on the outer surface as shown in FIG. Was diluted with 60% by weight of ethyl acetate, the isocyanate group content was 8.5%, and the solid content was 40% by weight.) Otherwise the first
This is the same as in the embodiment.

[0038] For those of this example, was subjected to a peeling test described above, also tearing of the rubber packing has occurred to that produced in the first embodiment. Therefore, it was confirmed that the rubber packing 33 was firmly adhered to the inner surface of the FRP joint body also according to the present embodiment.

[0039] In addition, the rubber tensile strength of this case 200
kg / cm ² and the peel strength was 25.0 kg / cm ² . (First Comparative Example) A pipe joint was manufactured in the same manner as in the first example except that the isocyanate was not applied to the outer surface of the ring-shaped rubber packing.

With respect to this pipe joint, when the rubber packing was pulled from the FRP joint body by hand by performing the above-described peel test, the rubber packing came off (peel strength was 0 kg / cm ² ). Therefore, in this comparative example, it was found that the FRP joint body and the rubber packing were not bonded. (Second Comparative Example) Coronate EH (isocyanate) was added with ethyl acetate for 20 minutes.
A pipe joint was manufactured in the same manner as in Example 2 except that the mixture was diluted by weight% (therefore, the isocyanate content was 80% by weight). However, in the second example, the application of the isocyanate was completed at about 60 g / m ² , whereas in this comparative example, it was not possible to apply the isocyanate uniformly unless it was about twice as large as about 150 g / m ² .

When the above-mentioned peeling test was performed on the pipe joint of this comparative example, the rubber packing was torn.

In this case, the rubber tensile strength is 200 kg.
/ Cm 2 and the peel strength was 26.0 kg / cm ² . (Third Comparative Example) The isocyanate (Desmodur R) used in the first example was further diluted with methylene chloride to give a solid content (isocyanate content) of 10% by weight and an isocyanate group content of 3.5 as a whole. %, Adjust the solution to be
A pipe joint was manufactured in the same manner as in the first example except that the solution was used.

[0043] As a result of the peeling test of the pipe joint, FRP
Rubber packing was slightly left on the joint body side. In this case, the rubber tensile strength is 200 kg
/ Cm ² , and the peel strength was 3 to 10 kg / cm ² . (Third Embodiment) FIGS. 7 to 11 show another example of the pipe joint manufactured by the present invention .
Shown in That is, this pipe joint 1 is different from the first embodiment in that
At the center of the inner surface 2a of the FRP joint body 2 of the manufactured pipe joint 1, a stopper rubber 5 is provided, and the ring-shaped rubber packing 3 and the stopper rubber 5 have a projection 3
d, 5c. Here, only the differences will be described, and other descriptions will be omitted. The same components as those of the pipe joint manufactured in the first embodiment are denoted by the same reference numerals.

The stopper rubber 5 is made of the same material as the ring-shaped rubber packing 3. The stopper rubber 5 includes a stopper portion 5a for regulating the insertion amount of the pipe 6 inserted into the joint body 2, and a pedestal portion for stabilizing the pipe 6 inserted from one side (in the present embodiment, the right side). 5b. Then, as shown in FIGS. 7 and 8, in a state where the stopper rubber 5 is mounted on the mold 10, the gap formed on the mounting surface between the stopper rubber 5 and the mold 10 is closed from the outer peripheral portion. The protrusions 5c are provided on both peripheral edges of the pedestal 5b.

The ring-shaped rubber packing 3 is also mounted on the mold 10 so as to close the gap formed on the mounting surface between the ring-shaped rubber packing 3 and the mold 10 from the outer peripheral portion so as to close the projection 3d. Is provided.

When the unsaturated polyester resin, which is the molding material of the FRP joint body 2, and the glass roving and chop are supplied to the outer periphery of the mold 10, they are provided on the ring-shaped rubber packing 3 and the stopper rubber 5. The protruding portions 3d and 5c prevent these molding materials from entering the mounting surface. As a result, as shown in FIGS. 9 and 10, the manufactured pipe joint 1 is manufactured without any unnecessary molding material attached to the ring-shaped rubber packing 3 and the stopper rubber 5. It is not necessary to remove unnecessary molding material in later post-processing.

In the present embodiment , the projections 3d and 5c having a claw-shaped cross section are provided. However, the shape of the projection 5c is such that the gap to the mounting surface can be closed. It is not particularly limited. That is,
As shown in FIG. 11, various shapes such as a semicircular cross section (a), a mountain-shaped cross section (b), and a tapered cross section (c) may be used. However, as shown in FIG. 10, in the case of the protrusions 3 d and 5 c having the shape of the claw blade shown in this example , after the FRP joint body 2 is formed, the protrusions 3 d and 5 c are attached to the FRP joint body. It is molded in a state of being buried in 2, and the appearance is beautifully finished.

[0048] Also, the protrusion 3d, 5c is the material may be identical to the body of the ring-shaped rubber packing 3 and the stopper rubber 5, but the workability is better hardness lower than these body, intrusion prevention capability Is preferred because of the high

[0049]

As described above, according to the present invention, in a pipe joint in which a ring-shaped rubber packing is provided on the inner surface of a FRP joint body, the interface between the joint body and the rubber packing is firmly bonded via isocyanate. Will be done. In addition, compared to the bonding operation using a normal adhesive, the isocyanate coating operation can be performed easily even by a non-expert, and furthermore, since no inclusions such as mats are used, the manufacturing cost is correspondingly reduced. I will use it. This makes it possible to easily mount the rubber packing on the inner surface of the joint body, and to realize an inexpensive pipe joint in which the rubber packing is firmly and integrally formed on the inner surface of the joint body.

[0050] In the other synthetic resin portion, i.e. FRP portion excluding the surface portions in the joint body, unaffected isocyanate, does not cause change in physical properties such as reduced tensile strength. Therefore, it is not necessary to consider such a change in physical properties at the time of manufacturing.

Further , according to the manufacturing method of the second aspect, it is possible to manufacture a pipe joint to which the thermosetting resin liquid and the reinforcing fiber unnecessary for the annular packing are not adhered. No need to work
The number of manufacturing steps and the manufacturing cost can be reduced.

[Brief description of the drawings]

[1] One of the pipe joint made with an example of the manufacturing method of the present invention
It is an axial longitudinal sectional view showing an example .

FIG. 2 is a partially enlarged longitudinal sectional view showing a part of a ring-shaped rubber packing in the pipe joint in an enlarged manner.

FIG. 3 is a process diagram showing a manufacturing process of the pipe joint, showing a state where a ring-shaped rubber packing is mounted on a mold.

FIG. 4 is a longitudinal sectional view showing the structure of the mold.

FIG. 5 is an explanatory view used to explain a peeling test of a rubber packing and showing a state in which the rubber packing is peeled off from a FRP joint body which is a test piece.

FIG. 6 is a partial longitudinal sectional view of a ring-shaped rubber packing used for a pipe joint manufactured in a second embodiment of the present invention.

FIG. 7 is a process diagram showing a manufacturing process of the manufacturing pipe joint according to the third embodiment of the present invention, showing a state where a rubber packing and a stopper rubber are mounted on a mold.

FIG. 8 is a partially enlarged longitudinal sectional view showing a part of a rubber packing and a stopper rubber in an enlarged manner.

FIG. 9 is a longitudinal sectional view showing a pipe joint manufactured in a third embodiment of the present invention.

FIG. 10 is a partially enlarged longitudinal sectional view showing a part of a rubber packing and a stopper rubber in FIG. 9 in an enlarged manner.

FIG. 11 is a partial longitudinal sectional view showing another embodiment of the projection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pipe joint 10 Die 2 FRP joint main body 2a Joint main body inner surface 3,33 Ring-shaped rubber packing 3d Projection 4 Isocyanate 5 Stopper rubber (ring-shaped rubber packing) 5c Projection

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-828 (JP, A) JP-A-3-114611 (JP, A) JP-A-49-15849 (JP, A) JP-A-51- 117326 (JP, A) JP-A-53-49325 (JP, A) JP-A-52-107621 (JP, A) Japanese Utility Model Application No. Sho 59-40684 (JP, U) Japanese Utility Model Application No. Sho 59-75989 (JP, U) JK 49-26747 (JP, Y1) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 70/00-70/88

Claims (2)

(57) [Claims] (1) The inner surface of a fiber-reinforced synthetic resin joint body is
Rubber packing is provided, and the main body and packing are
And a ring-shaped rubber packing is disposed on a predetermined outer peripheral surface of a cylindrical mold capable of expanding and contracting, and the cylindrical mold is provided with the rubber mold. The ring-shaped rubber packing is attached to a cylindrical mold in a state where the ring-shaped rubber packing has tension, and an isocyanate compound is applied to the outer peripheral surface of the ring-shaped rubber packing. Forming an uncured molding material layer composed of a thermosetting resin liquid and reinforcing fibers on the outer peripheral surface of the rubber packing and the cylindrical mold,
A method for manufacturing a pipe joint, comprising reducing the diameter of a cylindrical mold and removing the mold after curing the molding material layer. 2. The manufacturing method according to claim 1 , wherein the ring-shaped rubber packing is provided with a projection for closing a gap formed in a mounting surface between the ring-shaped rubber packing and the cylindrical mold. A method of manufacturing a pipe joint, comprising preventing a thermosetting resin liquid and a reinforcing fiber from entering a mounting surface from an outer peripheral portion of a ring-shaped rubber packing and a cylindrical mold.