JPS642048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to pipe joints made of reinforced plastic reinforced with fibers such as glass fibers, boron fibers, and organic fibers, particularly bent pipes such as L-shaped pipes and T-shaped pipes. The present invention relates to a method of manufacturing joints by a resin injection method.

PRIOR ART Pipe joints made of reinforced plastics have been known for a long time, and the manufacturing method for these pipe joints is usually a hand lay-up method (hand molding method). Since the hand lay-up method is a manual process, it is inefficient, requires skill, and has problems such as difficulty in obtaining homogeneous molded products and poor appearance. On the other hand, as a method for manufacturing reinforced plastic molded products, a resin injection method is known in which a male mold and a female mold are used, a fiber reinforcing material is attached to the gap between the molds, and then a synthetic resin liquid is press-fitted. This resin injecting method has the advantage of ensuring resin filling and making molded products with a beautiful appearance, but there are problems with demolding, especially of male molds, which limits its use and makes it suitable for pipe fittings. It was not used for molding. When trying to apply the resin injecting method to the molding of pipe fittings, if the pipe fitting has a straight shape, it is necessary to pull out the male mold (core mold) in one direction from one end of the molded pipe joint. However, in the case of so-called curved pipe joints that have shapes such as L, T, Y, U, cross, etc., it is not possible to remove the mold with a core mold of integral structure, and the core mold must be divided into many parts. It must be made into a mold. The assembly and disassembly of many split-type core molds is extremely complicated, making it difficult to improve productivity. If this is done, the resin liquid tends to enter the connecting part of the core mold, making it difficult to disassemble and remove the core mold, and the inner surface of the molded product must be finished to remove burrs. Because of these problems, the resin injection method has not actually been used to manufacture curved pipe joints.

Purpose of the Invention The present invention has been made in view of the current situation, and it aims to improve the productivity and quality of pipe joints, and to improve the productivity and quality of pipe joints. An object of the present invention is to provide a method for manufacturing a reinforced plastic pipe joint that allows the joint to be formed extremely easily.

Structure of the Invention The present invention is a method of molding a pipe joint by a resin injection method using an outer mold and a core mold,
As the outer mold, a rigid split mold having two or more parts is used, and as the core mold, a hollow elastic body having an integral structure is used. This core mold expands and contracts with the pressure applied to the internal hollow part, has shape retention properties at normal pressure, and can exhibit rigidity that can withstand resin injection pressure when an appropriate pressure is applied to the hollow part. It is. After installing the fiber reinforcement material in the gap between the outer mold and the core mold,
Pressurized fluid is supplied to the hollow part of the core mold to maintain the inside of the hollow part at a constant pressure so that the core mold has the necessary rigidity. In this state, a synthetic resin liquid is press-fitted into the gap between the outer mold and the core mold to integrate the fiber reinforcing material with the synthetic resin liquid and harden it. Thereafter, the pressure inside the hollow part of the core mold is reduced to normal pressure or negative pressure, and the core mold is pulled out from the molded product by utilizing its flexibility and removed from the mold. In this way, pipe fittings with complex shapes can be manufactured by the resin injection method and by using a core mold of integral structure.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. FIGS. 1 to 3 are diagrams showing an example in which the present invention is applied to molding an L-shaped pipe joint. In the same figure,
1 and 2 are two split molds that constitute a rigid outer mold (male mold), namely a lower mold and an upper mold, and these are divided into upper and lower halves at the center of the circumference of the pipe joint to be molded. There is. Note that, depending on the shape of the pipe joint to be molded, a mold divided into three or more parts may be used.
On one of the joint surfaces between the lower mold 1 and the upper mold 2 (lower mold 1 side in this example), a chemical-resistant rubber-like elastic body 7 with a thickness of about 1 to 10 mm is placed along the resin filling cavity.
The other side (upper die 2 side) is provided with a protrusion 8 having a shape that can be press-fitted to the rubber-like elastic body 7. The rubber-like elastic body 7 and the projection 8 prevent the resin press-fitted into the cavity from flowing out. Note that the arrangement of the rubber-like elastic body 7 and the protrusion 8 may be reversed.
Chemical-resistant rubber-like elastic bodies 12 for preventing resin outflow are also arranged in the circumferential direction near the ends of the inner surfaces of the lower mold 1 and the upper mold 2. Note that instead of being held by the lower mold 1 and the upper mold 2, the rubber-like elastic body 12 may be formed in an annular shape around the outer periphery of the core mold 4, which will be described later, or may be provided on both. The upper mold 2 has one or more resin injection ports 6 formed therein. Resin injection port 6
may be provided on the lower mold 1, or may be provided on both the upper mold and the lower mold.

The core mold 4 is composed of a hollow elastic body having an integral structure.
This hollow elastic body may be any material as long as it expands and contracts under the action of internal pressure, has shape retention under normal pressure, and exhibits rigidity to withstand the pressure of press-fit resin when subjected to appropriate internal pressure. A rubber hollow body with a thickness of 4 to 6 mm is suitable. The wall thickness of 4 to 6 mm was chosen because if it is thinner than this, the shape retention under normal pressure and rigidity during molding will be insufficient, resulting in uneven wall thickness of the molded pipe fitting. This is because demolding becomes difficult unless the applied pressure and reduced pressure are increased. However, locally increasing the thickness has no effect on demolding, so there is no problem. The core mold 4 has a flange 13 at the end, and an annular convex portion 14 on the outer peripheral surface near the end. On the other hand, a recess 15 is formed on the inner surface of the outer mold facing the protrusion 14 .

Next, a method of forming a pipe joint using the above-mentioned outer mold and core mold will be explained.

First, the glass fiber reinforcement material 3 is placed in the cavity of the lower mold 1. As the glass fiber reinforcing material at this time, preform mat, chopped strand mat, roving cloth, glass cloth, etc. are used singly or in combination. A core mold 4 is placed on top of the glass fiber reinforced material 3, a glass fiber reinforced material 5 is further placed on top of the core mold 4, and the upper mold 2 is closed. Note that instead of this procedure, the core mold 4 may be first wrapped with glass fiber reinforcement, the core mold 4 may be placed inside the lower mold 1, and the upper mold 2 may be closed.

Next, a sealing lid 9 is attached to the end faces of the lower mold 1 and the upper mold 2 with the flange 13 of the core mold 4 in between, and pressurized fluid is supplied from the injection port 10 to the hollow part in the core mold 4 to pressurize it. The core mold 4 is inflated to the necessary inner diameter for the pipe joint 11 to be molded. The pressurized fluid used here may be a liquid such as water or oil, but it is convenient to use air for operational reasons. In other words, liquids require recovery operations, but air only needs to be released into the atmosphere after use.
In addition, switching to depressurization operation is easy. The following description will be made assuming that air is used. The air pressure for inflating the core mold 4 may be determined as appropriate depending on the size of the molded product (pipe joint), the wall thickness of the core mold 4, the elastic modulus, etc., but it is preferably 0.5 to 2 Kg/cm ² . Incidentally, if the molded product becomes larger, it is necessary to increase the resin liquid injection pressure, and it is preferable to set the internal pressure of the core mold to be high accordingly.

Thereafter, a cold-curing unsaturated polyester resin or epoxy resin is press-fitted into the gap between the outer mold and the core mold through the resin injection port 6 of the upper mold 2 by a conventional resin injection method. After the injected resin has hardened, when the pressure on the core mold 4 is stopped and the inside pressure is returned to normal pressure, the core mold 4 contracts due to its own elasticity, and the molded pipe fitting 11
Release from the mold. At this time, in some cases, the core type 4
The internal pressure is reduced to negative pressure. When the inside of the core mold 4 is made to have a negative pressure, the amount of contraction of the core mold becomes large, and mold release becomes more reliable. Next, the sealing lid 9 at the end of the core mold 4 is released, and the upper mold 2 is removed. After that, core type 4
is folded inside the pipe joint 11, taken out from the socket of the pipe joint 11, and the pipe joint 11 is removed from the lower mold 1. Note that the core mold may be taken out after demolding the pipe joint 11. In this way, an L-shaped pipe joint 1 made of reinforced plastic is manufactured.

In this embodiment, an annular convex portion 14 is provided on the outer peripheral surface near the end of the core mold 4, and a recess 15 is provided on the corresponding portion of the outer mold.
, the pipe wall near the end of the molded pipe fitting 11 protrudes in an annular shape on the outer periphery and forms an annular recessed part on the inner periphery. Pipe joints having a concave part on the inner periphery are extremely preferable because during construction, the joint can be completely sealed by simply inserting the annular rubber packing into the concave part and then inserting the straight pipe. .

FIG. 4 shows another embodiment of the method of attaching the sealing lid 9. As shown in FIG. In this embodiment, an inward flange 16 is provided at the open end of the core mold 4A, and a sealing lid 9 is attached using a stopper plate 17 fixed to the inside of the flange 16.
A sealing lid 9 is placed in the groove 18 formed in the lower mold 1 and the upper mold 2.
We are using a method of fitting and fixing the parts. According to this method, before setting the core mold 4 on the outer mold,
Since the sealing lid 9 can be attached to the core mold, it is easy to attach and remove it, and if a plurality of core molds with sealing lids are prepared in advance, work efficiency can be significantly improved.

Effect of the invention According to the present invention, the following effects can be obtained.

(1) Since a hollow elastic body with an integral structure is used as the core mold, there is no need for disassembly and assembly, which is required when using a split core mold, and demolding is extremely easy as the internal pressure is maintained at normal or negative pressure. can be done. As a result, it has become possible to use the resin injection method for molding pipe joints.

(2) Since molding is performed using the resin injection method, pipe fittings of stable quality can be obtained without requiring highly skilled workers unlike the hand lay-up method.

(3) Much more productive than the traditional hand lay-up method.

(4) The appearance is beautiful because a highly rigid outer mold is used. Furthermore, since it is a resin injection method, the resin is reliably filled and a defect-free product can be obtained.

(5) Since a core mold made of a hollow elastic body is used, it is possible to remove the mold even if a convex portion is formed on the outer periphery of the core mold, and by providing a convex portion 14 on the outer periphery of the core mold as in the illustrated embodiment, A pipe joint having a concave portion on the inner periphery can be easily manufactured.

[Brief explanation of the drawing]

FIG. 1 shows an outer mold used in an embodiment of the method of the present invention.
A front sectional view showing the state in the middle of assembling the core molds,
Figure 2 is a side sectional view of the end of the mold with the outer mold and core mold combined and resin injected, Figure 3 is a horizontal sectional view in the same state as Figure 2, and Figure 4 is another example. FIG. 2 is a side sectional view similar to FIG. 2 illustrating an example; DESCRIPTION OF SYMBOLS 1... Lower mold, 2... Upper mold, 4... Core mold, 3, 5... Glass fiber reinforcement material, 6... Resin injection port, 11... Pipe joint.

Claims (1)

[Claims] 1 After using an outer mold made of a rigid split mold of two or more parts and a core mold made of a hollow elastic body of integral structure, and installing fiber reinforcement material in the gap between the outer mold and the core mold. , supplying pressurized fluid to the hollow part of the core mold to maintain the inside of the hollow part at a constant pressure, and in this state,
A synthetic resin liquid is press-fitted into the gap between the outer mold and the core mold to integrate the fiber reinforcement material and the synthetic resin liquid, and after curing, the pressure inside the hollow part of the core mold is set to normal pressure or negative pressure to produce a molded product. A method for manufacturing reinforced plastic pipe joints, which is characterized by demolding.