JP2003094448A - Manufacturing method for frp hollow structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily mold an FRP hollow structure of a complicated shape. SOLUTION: After arranging a reinforcing fiber base material on the outer periphery of a hollow core comprising an elastic material, the core is fitted in a die. Then, a resin is poured in, and the reinforcing fiber base material is impregnated with the resin. After the resin is hardened, the pressure in the core is reduced, an the core is shrink-deformed. The shrink-deformed core is taken out from a molded FRP hollow structure for this manufacturing method for the FRP hollow structure.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing an FRP hollow structure, and more particularly to a method for manufacturing an FRP hollow structure molded by using a hollow core and a mold.

[0002]

2. Description of the Related Art Conventionally, a hollow core, for example, a stretchable rubber tube is used as a core, a reinforcing fiber base material is arranged on the outer periphery of the core, and the core is set in a mold and the inside of the rubber tube is pressurized. A molding method known as internal pressure molding is known in which a reinforcing fiber base material is impregnated with a resin in this state.

In such a molding method, a rubber-made tubular core is usually used, and the rigidity is low, so that it is difficult to cope with the molding of a large structure or a structure having a complicated shape. Also, when molding a relatively large FRP hollow structure, it is difficult to handle the expandable core, and it is difficult to perform a predetermined molding. Furthermore, the core used for molding is usually left as it is in the molded body,
It is difficult to remove the core after molding. In particular, it is more difficult when the molded product is large, has high rigidity, has a complicated shape, or has an undercut shape.

[0004]

The problem to be solved by the present invention is whether it is an FRP hollow structure having a complex-shaped portion or a relatively large FRP hollow structure.
An object of the present invention is to provide a method for manufacturing an FRP hollow structure which can be easily and inexpensively molded, and can be molded a plurality of times using the same core, that is, can be mass-produced.

[0005]

In order to solve the above-mentioned problems, a method for producing an FRP hollow structure according to the present invention is a method in which a reinforcing fiber base material is placed on the outer periphery of a hollow core made of an elastic material. Insert the core into the mold, inject the resin to impregnate the reinforcing fiber base, cure the resin, and then depressurize the core to shrink and deform the core, and mold the shrink-deformed core. FR
The method is characterized by taking out from the P hollow structure.

In the method for manufacturing the FRP hollow structure described above, after the resin is cured, the core is placed in a heating furnace together with the molded FRP hollow structure, and after-curing the FRP hollow structure by heating, It is also possible to decompress the inside of the core that has been softened by heating so that the core is contracted and deformed, and the contracted and deformed core is taken out from the molded FRP hollow structure.

The hollow core to be used may be made of rubber, but is preferably made of a thermoplastic resin. As a thermoplastic resin,
For example, polyethylene can be used. The hollow core made of such a material can be produced by blow molding or rotational molding. Since it is blow molding or rotational molding of resin, even a core having a complicated shape can be easily manufactured as long as a mold for core molding can be manufactured.

In the method according to the present invention, the core is expanded toward the inner surface of the cavity by pressurizing the inside of the core or / and depressurizing the inside of the cavity of the mold before injecting the resin. You may allow it. By doing this, the reinforcing fiber base material arranged on the outer periphery of the core can be pressed along the inner surface of the cavity,
Since the resin is impregnated in this state, it is possible to more accurately form the target shape and improve the surface quality of the formed product.

Further, the hollow core used in the method according to the present invention can be repeatedly used. That is, after the contracted and deformed core is taken out from the molded FRP hollow structure, the inside of the core is pressurized, particularly the inside of the core softened by heating is pressurized to initialize the shape of the core. It is possible to restore the shape and use it for the next molding of the FRP hollow structure. The number of times of repeated use depends on the restored state of the core to the initial shape, but it can be repeated at least several times, and the cost merit in molding a relatively large FRP hollow structure is extremely large.

In the method for manufacturing an FRP hollow structure according to the present invention as described above, a hollow core made of an elastic material is preliminarily molded and prepared, and a reinforcing fiber base material is arranged on the outer periphery of the core. Since the resin is injected and impregnated after the FRP hollow structure having a complicated shape is mounted in the mold, it is possible to relatively easily mold the FRP hollow structure. Also,
By making the core from an elastic material that is elastically deformable but has its own shape-retaining property instead of elastic rubber, handling during molding becomes easy, and a relatively large F
Even an RP hollow structure can be easily molded.

After molding the FRP hollow structure, the hollow core is contracted and deformed by internal decompression, and taken out from the molded FRP hollow structure. Therefore, FR after molding
It is also possible to avoid the core remaining in the P hollow structure. In addition,
A mold release agent or a mold release sheet may be appropriately arranged so that the core and the molded FRP hollow structure during pressure reduction can be easily separated from each other. The core taken out can be restored to the initial shape by pressurizing the inside, and can be repeatedly used for molding at least several times. Therefore, the core manufacturing cost per product is significantly reduced, and the FRP
It becomes possible to mass-produce the hollow structure at low cost.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. 1 to 6 are
1 shows a method for manufacturing an FRP hollow structure according to an embodiment of the present invention, and particularly shows an example of forming a fuselage of a small airplane. However, the present invention is not limited to this, and is applicable to molding of any FRP hollow structure.

First, a hollow core 1 as shown in FIG. 1 is prepared. The core 1 is made of an elastic material, particularly a thermoplastic resin, and is made by blow molding using polyethylene in this embodiment. For molding the hollow core,
It is also possible to perform so-called rotational molding, in which resin powder is charged into a rotating mold, and the resin powder is dispersed along the inner surface of the mold and melt-molded. The wall thickness of the hollow core 1 is, for example, about 2 to 5 mm. On the outer surface of the core 1, FRP
The groove 2 for molding the frame portion of the hollow structure is formed, and the resin groove 3 which serves as a resin flow path for favorably diffusing the resin at the time of resin injection described later is formed.

On the outer periphery of the hollow core 1, a reinforcing fiber base material 4 is arranged, for example, as shown in FIG. The reinforcing fiber base material 4 can be prepared in advance in the form of divided preforms according to the part of the FRP hollow structure to be molded, and it is mounted on the outer periphery of the core 1. This will make layup easier. Also in the form of the preform of the reinforcing fiber base material 4, depending on the part of the FRP hollow structure, for example, the frame part, the outer skin part, or the like, only a plurality of reinforcing fiber base materials are laminated, or the reinforcing fiber base material. It can be formed to have a core material interposed between base materials. It is preferable to use a lightweight foam (for example, urethane foam) or a honeycomb structure as the core material.

The reinforcing fibers used for the reinforcing fiber base material 4 are not particularly limited, and carbon fibers, glass fibers, aramid fibers, and hybrid forms thereof can be used, depending on the application and required characteristics. It may be selected appropriately.

A core 1 having a reinforcing fiber base material 4 arranged on the outer periphery thereof.
Is mounted in a mold 5 as shown in FIG. Mold 5
In the present embodiment, the mold is composed of molds 5a and 5b, and by closing them, the cavity 6 having a predetermined shape is formed inside.
Is formed. At this time, a gel coat 7 may be applied to the inner surface of the cavity 6 if necessary.

When the core 1 on which the reinforcing fiber base material 4 is arranged is mounted in the mold 5, for example, the state shown in FIG. 4 is obtained. That is, the reinforcing fiber base material 4 having a laminated structure, the sandwich structure portion having the core material 8, and the like are arranged on the outer periphery of the core 1, and are mounted in the cavity 6. At this time,
When a gap is formed between the reinforcing fiber substrate 4 and the inner surface of the cavity 6 as shown in FIG.
By depressurizing the inside by vacuuming and / or pressurizing the inside of the core 1, the core 1 can be expanded toward the inner surface of the cavity 6 and pressed against the inner surface to eliminate the gap. By the expansion of the core 1 as described above, the reinforcing fiber base material 4 is formed in a straight state with no looseness in the circumferential direction, and the original high mechanical characteristics can be exhibited.

In this state, while heating the mold to a predetermined temperature (for example, about 70 ° C.), the resin 10 is injected into the cavity 6 from the resin tank 9 as shown in FIG. Although a pump can be used for injecting the resin, the resin can be naturally introduced into the cavity 6 by injecting the resin while depressurizing the inside of the cavity 6 with the vacuum line 11. The injected resin 10 flows through the resin groove 3 and the reinforcing fiber base material 4 described above, and is quickly impregnated into the reinforcing fiber base material 4. As the injection resin, a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, a bismaleimide resin, a thermosetting polyimide resin, or a phenol resin is used.

After the resin is injected, if the mold 5 is heated to the predetermined temperature and kept for a predetermined time, the resin starts to gel in about 40 minutes, and the resin is hardened in about 2 hours.

After the resin is cured, the molded FRP hollow structure is removed from the mold 5 together with the core 1. After that, if necessary, it is put in a heating furnace and heated to about 120 ° C. to perform after-curing. However, this compulsory after-cure is unnecessary in some cases, and it is also possible to simply leave the after-cure. When the after-curing is performed at a high temperature, the core 1 remaining inside the molded FRP hollow structure can be softened, which facilitates the next core removal.

While performing the above-mentioned after-curing, the inside of the core 1 is decompressed by suction to shrink and deform the core 1 as shown in FIG. 6 to form the shrink-deformed core 21.
The hollow structure 22 is taken out. Especially as mentioned above, 120
When the core 1 is depressurized while performing after-curing at about ℃, the core 1 is softened and easily contracts and deforms,
Moreover, since the core 21 that has been contracted and deformed is also flexible, it can be taken out from the FRP hollow structure 22 more easily.

In forming the FRP hollow structure 22 as described above, the hollow core 1 having a predetermined shape is prepared in advance, so that even a structure having a complex-shaped portion can be easily formed. You can Also, the resin core 1 is
Since it has a relatively high rigidity at room temperature, it is easy to handle from the lay-up of the reinforcing fiber base material 4 to the mounting in the mold 5, and even when molding a relatively large structure,
The molding operation is extremely easy.

After the FRP hollow structure 22 is molded, the core 1 in a softened state due to high temperature can be easily contracted and deformed by internal decompression, and the contracted and deformed core 2 is obtained.
The removal of 1 is also very easy.

The extracted contracted and deformed core 21 is in a state similar to that of a balloon that has been deflated, so that it is possible to restore the initial shape (the shape shown in FIG. 1) by pressurizing the inside. Yes, so that it can be used repeatedly for the same molding. It is more effective to perform the restoration work to the initial shape while heating the shrinkage-deformed core.
Although it depends on the shape maintenance state of the core 1, it can be used repeatedly enough at least several times.

Further, as shown in FIG. 4, if the core 1 is expanded toward the inner surface of the cavity 6 and then the resin is injected, a more accurate shape can be formed along the inner surface of the cavity 6. In addition, the surface of the molded product becomes smoother and the surface quality can be improved.

[0026]

As described above, according to the method for manufacturing an FRP hollow structure of the present invention, an FRP hollow structure having a complex-shaped portion and a relatively large FRP hollow structure can be easily and accurately manufactured. It becomes possible to integrally mold to a target shape well. Also, the workability of a series of molding is good, and moreover,
Since the core can be used repeatedly, the desired FRP
The hollow structure can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view of a core used in a method for manufacturing an FRP hollow structure according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which a reinforcing fiber base material is laid up on a core.

FIG. 3 is an exploded perspective view of a mold.

FIG. 4 is a schematic vertical sectional view showing a state in which a core and a reinforcing fiber base material are mounted in a mold.

FIG. 5 is a perspective view showing a state of resin injection.

FIG. 6 is a perspective view showing how the core is taken out.

[Explanation of symbols]

1 hollow core 2 Frame forming groove 3 resin groove 4 Reinforcing fiber base material 5, 5a, 5b mold 6 cavities 7 gel coat 8 core material 9 Resin tank 10 resin 11 Vacuum line 21 Shrinkage-deformed core 22 FRP hollow structure

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akihiko Kitano             1515 Tsutsui, Oita, Matsumae-cho, Iyo-gun, Ehime             Les Ehime Factory (72) Inventor Yasuhiro Tsuchiya             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Yuichi Takano             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Hiroyuki Koyama             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F-term (reference) 4F202 AA36 AD16 AG07 AJ03 CA01                       CB01 CK42 CK82 CM30 CM90                 4F204 AA36 AA37 AA39 AA40 AA41                       AD16 AG07 AJ03 AJ11 EA03                       EA04 EB01 EB11 EF05 EF27                       EK13 EK17 EK24 EK25

Claims (7)

[Claims] 1. A hollow core made of an elastic material is provided with a reinforcing fiber base on the outer periphery thereof, and then the core is mounted in a mold and resin is injected to impregnate the reinforcing fiber base to cure the resin. After that, the pressure inside the core is reduced to cause the core to contract and deform, and the contracted and deformed core is taken out from the molded FRP hollow structure. 2. After curing the resin, the core is put into a heating furnace together with the molded FRP hollow structure, and the core is heated by heating.
After curing the RP hollow structure, decompress the inside of the core softened by heating to shrink and deform the core,
The method for producing an FRP hollow structure according to claim 1, wherein the shrink-deformed core is taken out from the molded FRP hollow structure. 3. The method for producing an FRP hollow structure according to claim 1, wherein the hollow core is made of a thermoplastic resin. 4. The method for producing an FRP hollow structure according to claim 1, wherein the core is produced by blow molding or rotational molding. 5. The core is expanded toward the inner surface of the cavity by pressurizing the inside of the core or / and depressurizing the inside of the cavity of the mold before injecting the resin.
The method for manufacturing the FRP hollow structure according to claim 1. 6. After the contracted and deformed core is taken out from the molded FRP hollow structure, the inside of the core is pressed to restore the shape of the core to the initial shape, and the next molding of the FRP hollow structure is performed. The FRP according to any one of claims 1 to 5, which is used for
Hollow structure manufacturing method. 7. After taking out the core from the FRP hollow structure, the inside of the core is pressurized while the core is softened by heating to restore the shape of the core to the initial shape. FR
The method for producing an FRP hollow structure according to claim 6, which is used for molding a P hollow structure.