JPH0295834A - Inner mold for molding frp pipe coupling - Google Patents

Abstract

PURPOSE:To improve dimensional accuracy, and facilitate mold release, and also make the mold producing cost to be inexpensive by constituting of the divided structures comprising the number of closed hollow body equivalent to the numbers of pipe coupling to be molded. CONSTITUTION:Fitting protrusions 19a, 19a of an ellipse shape is formed on the joining surface of a divided structure 2 in such a manner that the long axis may be perpendicular to the axial core of the divided structure 2, while ellipse-shaped fitting recessed parts 19b, 19b fitted with the fitting protrusions 19a, 19a are formed on each joining surface of divided structures 3, 4, and the fitting protrusion 19a and fitting recessed part 19b are fitted to each other so as to integrate the divided structure 2, 3, 4. In consequence, the divided structures 2 and 3 become the same in their shapes of joining molded parts 8, 9, so that the auxiliary mold 24 for the divided structure 2 and the auxiliary mold 26 for the divided mold 26 can be made the same as each other. Thus, the total amount of only three, namely, a main mold 21 and to kinds of auxiliary molds 22, 24(26) are sufficient for the molds to mold respective divided structures 2, 3, 4, as a result, the manufacturing cost of molds is reduced considerably.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is utilized in the technical field of molding fiber-reinforced thermosetting resin (hereinafter referred to as FRP), in which glass fibers are impregnated with a thermosetting resin material. In particular, it relates to an inner mold for molding FRP pipe joints.

(Prior art) As this type of internal mold, conventionally, for example,
Those disclosed in Japanese Patent Publication No. 89, Japanese Patent Publication No. 57-7890, or Japanese Patent Publication No. 45-6957 are known.

The inner mold described in Japanese Patent Publication No. 57-7889 G is made of a low-melting point material, and is designed to be removed from the molded product by heating to soften or melt it after molding.

Further, the inner mold described in Japanese Patent Publication No. 57-7890 is made of a brittle material, and is designed to be removed from the molded product by crushing it with a suitable jig after molding.

The inner mold described in Japanese Patent Publication No. 45-6957 is made of a thermoplastic resin pipe, and after molding, both ends are sealed, heated and softened, and the air inside is suctioned to cause buckling, so that the molded product can be separated from the molded product. It is designed to remove the mold.

(Problem to be solved by the invention) However, in any of the above inner molds, for example, T
It has been difficult or impossible to apply this method to molded products with complex shapes such as joints. In other words, the above-mentioned Special Publication Publication No. 57-7
In the case of the inner mold described in Publication No. 889 and Japanese Patent Publication No. 45-6957, the inner mold after softening or buckling gets caught inside the molded product and cannot be pulled out.
In the case of the inner mold described in Japanese Patent Publication No. 7890, there were problems in that the inner mold was difficult to crush, and moreover, crushed debris remained on the inner surface of the molded product, degrading the quality of the molded product.

In view of these conventional problems, the present invention provides an inner mold for molding an FRP pipe joint that has high dimensional accuracy, is easy to demold, and can reduce mold manufacturing costs.

(Means for Solving the Problems) In order to achieve the above object, an inner mold for molding an FRP pipe joint according to the present invention is composed of a number of divided bodies corresponding to the number of sockets of a pipe joint to be molded. Each of these divided bodies is made of a sealed hollow body made of synthetic resin, and by temporarily joining these divided bodies to each other, they can be integrated into a predetermined shape so as to be separable.

(Function) Since the mold is composed of a plurality of divided bodies, the dimensional accuracy of the entire mold depends on the dimensional accuracy of each divided body. And since the volume of the divided body is naturally smaller than the whole mold,
A mold with higher dimensional accuracy can be easily obtained than when the entire mold is constructed from one piece. In addition, if the shapes of the sockets of the molded product are the same, it is possible to use a common mold for forming the divided bodies.
It becomes possible to reduce the number of molds. Furthermore, when demolding, each segment is heated to soften it, remove air and buckle, and then each segment is pulled out from the molded product. At this time, since each divided body is separated from the mutual joint portion, it can be easily demolded without being caught in the molded product.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a front view showing an example in which the present invention is applied to an inner mold for forming a T-shaped pipe joint as an FRP pipe joint, and Fig. 2 is an inner mold for forming a bend pipe joint as an FRP pipe joint. FIG. 2 is a front view showing an example to which the present invention is applied.

First, to explain an example of the inner mold for forming a T-shaped pipe joint shown in FIG. 1, this inner mold 1 is composed of three divided bodies 2.3. are each made of a sealed hollow body made of synthetic resin, and the divided bodies 2 and 3 become like this.
．． 4 are integrated into a T-shape (inverted T-shape in the figure) so that they can be separated by temporarily joining them together.

Each divided body 2.3.4 has four parts, namely, a support end forming part 5 for forming a support end supported by a rotational shaft (not shown) of a molding machine, and a molded product (not shown). A receiving recess molding part 6 for molding the socket part (omitted), a trunk molding part IO for forming the body of the molded product, and a joint molding part 7 for molding the joint part (8, 9) are integrally molded by blow molding, and the joint molded portion 7,
8゜9 (the parts are formed in the same shape.Then, the divided bodies 2, 3.4 that become like this are formed on the joint surfaces of the respective joint molding parts ?, 8.9, which will be described later. The fitting protrusions 19a and the fitting recesses 19b allow them to be joined to each other in a separable manner.As the synthetic resin constituting the divided bodies 2, 3.4, thermoplastic resins such as polypropylene can be used. Synthetic resin is preferable.

Moreover, the inner mold 11 for forming a bend pipe joint shown in FIG.
It is composed of two divided bodies 12 and 13, and these divided bodies 12 and 13 are
．． Each of the divided bodies 12 and 13 is made of a sealed hollow body made of synthetic resin, and is integrated into an L-shape so that the divided bodies 12 and 13 can be separated by temporarily joining each other.

In the case of this inner mold 11 as well, as in the case of the above-mentioned inner mold 1 for forming a T-shaped pipe joint, each of the divided bodies 12 and 13 has four parts.
It consists of two parts. That is, a support end molding section 14 for molding a support end to be supported on a rotating shaft (not shown) of a molding machine, and a receiving recess molding section for molding a socket of a molded product (not shown). 15, a body part molding part 18 for forming the body part of the molded product, and a joint part molding part 16 (17) for molding the joint part are integrally molded by blow molding. The divided bodies 12.13 thus formed can be separably joined to each other by a fitting protrusion 20a and a fitting recess 20b, which will be described later, formed on the joint surfaces of the respective joint molded parts 16.17. is being done.

Each of the divided bodies 2.degree. 3.4 of the inner mold 1 for molding the T-shaped pipe joint is molded using a mold as shown in FIGS. 3 to 5. As shown in FIG. 3, the mold 23 for molding the vertically divided body 2 includes a main mold for molding the support end molding part 5, the socket molding part 6, and the body molding part 10. A mold 21 and a sub-mold 2 for molding the joint molding portion 7
It consists of two molds. These main molds 21
and the sub mold 22 can be removably integrated with each other by a fitting means 23a. Furthermore, the divided body 3 located on the left side in FIG. 1 is different from the divided body 1 described above only in the shape of the joint molding portion 8, and therefore, as shown in FIG. and joint molding part 8
It is molded using a sub-mold 24 exclusively for molding. Furthermore, like the divided body 3, the remaining divided body 4 is also molded by the above-mentioned main mold 21 and a sub-mold 26 for exclusively molding the joint molding portion 9.

Here, as shown in FIG. 8, oval fitting protrusions 19a, 19a are formed on the joining surfaces of the divided bodies 2, respectively, so that their long axes are perpendicular to the axis of the divided bodies 2, Split body 3
and forming oval fitting recesses 19b, 19b on each joint surface of the divided body 4 to fit with the fitting protrusions 19a, 19a,
When the divided bodies 2, 3.4 are integrated by fitting these fitting protrusions 19a and fitting recesses 19b, the left and right divided bodies 2 and 3 have their joint molded parts 8
, 9 have the same shape, the above-mentioned divided body 2
The sub-mold 24 for the split body 3 and the sub-mold 26 for the divided body 3 can have the same shape.

Therefore, it is sufficient to prepare a total of three molds for molding each of the divided bodies 2, 3.4: the main mold 21 and two types of sub-molds 22, 24 (26). It becomes possible to significantly reduce mold manufacturing costs.

On the other hand, each divided body 12 of the inner mold 11 for forming a bend pipe joint.
13 is a mold 30.3 as shown in FIGS. 6 and 7.
2, but these molds 30.
The configuration of 32 is also the same as that of the mold for the above-described inner mold 1 for molding a T-shaped pipe joint. That is, the mold 30 shown in FIG. It is composed of two molds, a sub-mold 29 for the purpose of The mold 32 shown in FIG. 7 is composed of two molds: the main mold 28 and a sub-mold 31 for molding the joint molding portion 17. Here, as shown in FIG. 10, a pair of fitting protrusions 20a are provided on each joint surface of the divided body 12 and the divided body 13, respectively.
When the fitting recess 20b and the fitting recess 20b are formed so as to be aligned in a direction perpendicular to the direction toward the center of curvature of the bend pipe joint and to be symmetrical with respect to the center of the joint surface, the divided body 12 and the divided body 13 are formed. Since the shapes of the joint molding parts 16 and 17 are the same, the sub-mold 29 for the above-mentioned divided body 12 and
The sub mold 31 for the divided body 13 can have the same shape. Therefore, the molds for molding each divided body 12.13 include the main mold 28 and one sub-mold 29 (31
), it is only necessary to prepare a total of two molds, making it possible to significantly reduce the manufacturing cost of the mold.

Furthermore, each divided body 2, 3 of the inner mold 1 for forming a T-shaped pipe joint and the inner mold 11 for forming a bend pipe joint described above 4.12.13
Is the shape of each joint molded part? , 8.9, 16.
If they are the same except for 17, the main molds 21 and 28 for molding the inner molds 1 and 11 can be made common. Therefore, it is possible to manufacture many types of inner molds for forming pipe joints with a small number of molds, which is convenient because the manufacturing cost of the molds can be further reduced.

FIG. 12 shows the state of molding using the mold described above.

In this figure, the divided body 3 is about to be molded,
When the synthetic resin P in a molten state is supplied from the extruder E to the inside of the mold 25 via the parison controller C, the synthetic resin P is swollen by air blown from the nozzle N facing the lower end of the mold 25. The divided body 3 is molded in close contact with the mold surface of the mold 25 and hardened by the cooling action of the water cooling means J provided in the mold 25, thereby obtaining the divided body 3 in the form of a closed hollow body.

Note that the shapes of the divided bodies 2, 3, 4, 12, 13, the shapes and numbers of the fitting protrusions 19a, 20a and the fitting recesses 19b, 20b, etc. are not limited to those shown in the illustrated example.

Next, the procedure for molding a pipe joint using the inner mold for molding an FRP pipe joint according to the present invention will be described, taking as an example the case of molding a T-shaped pipe joint.

The inner mold used for molding is the inner mold 1 shown in FIG. 1 described above. First, three divided bodies 2. 3. 4 are temporarily joined into a predetermined shape (T-shape) by fitting the respective fitting protrusions 19a and fitting recesses 19b. At this time, if the above-mentioned fitting means alone is insufficient in terms of strength, an adhesive is used in combination. This adhesive includes a split body, 3.4
For example, a true melt adhesive that melts at a temperature lower than the softening temperature of the synthetic resin constituting the adhesive is preferably used.

After the divided bodies 2, 3.4 are assembled as described above, FRP made of glass fiber impregnated with a thermosetting resin is wound around the inner mold 1 and heated and hardened.

After hardening, the inner mold 1 is softened by heating, and each divided body 2.3.
Either air is sucked from each of the divided bodies 2, 3.4 to buckle them, or each divided body 2, 3.4 is buckled around its respective axis. Finally, each divided body 2, 3.
4 are pulled out from the sockets of the molded product, demolding is completed, and a molded product is obtained. At this time, since the divided bodies 2, 3.4 are only temporarily joined, the above-mentioned pulling out can be performed without any support. Furthermore, even if the adhesive described above is used for temporary bonding, the adhesive will melt before the inner mold 1 softens, so each buckled divided body 2, 3, 4
can be easily pulled out.

Although the case of forming a T-shaped pipe joint has been described above, the case of forming a bend pipe joint is also similar to the above.

Note that the inner mold for molding FRP pipe joints according to the present invention is not limited to molding pipe joints as in the above embodiments, but can also be used for molding pipes such as short pipes in which two or more branch pipes are provided on the pipe wall. It can also be applied to molding joints, Y-shaped pipe joints, or reducers.

(Effects of the Invention) As explained above, the inner mold for molding an FRP pipe joint of the present invention is composed of divided bodies each having a number of sealed hollow bodies corresponding to the number of sockets of the pipe joint to be molded. Therefore, the dimensional accuracy can be easily improved compared to the case where the entire mold is molded at once. Therefore, a molded article with high dimensional accuracy can be obtained, and this method is particularly effective when molding a large-sized molded article.

Furthermore, if the shapes of the respective socket portions of the molded product are the same, the divided bodies can be made common, and the number of molds for molding the divided bodies can be reduced. Therefore, production costs can be further reduced.

Furthermore, since it consists of a plurality of divided bodies, and each divided body is a sealed hollow body made of synthetic resin, and is integrated by temporarily joining each other, demolding from the molded product requires that each divided body be This can be done with an extremely simple operation of heating and softening the molded product, removing air or twisting it to cause it to buckle, and then pulling out each segment from each socket of the molded product. Therefore, it can be applied to pipe joints of any complicated shape.

[Brief explanation of drawings]

The drawings illustrate embodiments of the invention; FIG. 1 shows a T-shaped FR
A side view of the inner mold for PTM manual molding, Figure 2 is a front view showing the inner mold for molding a pend-shaped FRP pipe joint, and Figures 3 to 5.
The figure is a central longitudinal sectional view showing the mold for forming each divided body constituting the inner mold for molding the FRP pipe joint shown in Fig. 1,
Figures 7 and 7 are central vertical cross-sectional views showing the molds for molding each divided body constituting the inner mold for molding a bend-shaped FRP pipe joint, and Figure 8 is a central vertical sectional view showing the mold for molding the FRP pipe joint shown in Figure 1. FIG. 9 is a partially cutaway front view showing the joined state of the joint molded parts of each divided body forming the inner mold, and FIG. Front view showing the shape,
Fig. 10 is a partially cutaway front view showing the joined state of the joint molding parts of each divided body constituting the inner mold for molding the FRP pipe joint shown in Fig. 2, and Fig. 11 is a partially broken front view showing the joint state of the joint molding parts of the divided bodies composing the inner mold for molding the FRP pipe joint shown in Fig. 2. FIG. 12 is a front view showing the shapes of a fitting protrusion and a fitting recess formed on the surface, and a schematic sectional view showing an example of blow molding of a divided body constituting an inner mold for molding an FRP pipe joint. 1.11...Inner mold for forming FRPi joint 2.3.4,1
2.13...Divided body

Claims (1)

[Claims] 1) It is composed of a number of divided bodies corresponding to the number of sockets of the pipe joint to be molded, and each of these divided bodies is a sealed hollow body made of synthetic resin, and these divided bodies are temporarily joined to each other. An inner mold for forming an FRP pipe joint, characterized in that the inner mold is separably integrated into a predetermined shape by