JP2947867B2 - Method for forming composite material and method for forming mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a fiber-reinforced resin composite material used for structural members of aircraft and the like, and a method for forming a mold used for the same.

[Conventional technology]

BACKGROUND ART A fiber-reinforced resin composite (hereinafter, referred to as a composite) has excellent specific strength and specific rigidity, and thus has been significantly applied to structural members of an aircraft body in recent years.

Generally, in the molding of this type of structural member, prepregs cut to a predetermined size are laminated on a molding jig while changing the fiber direction one by one for a required number of sheets, and first, an external pressure is applied to the prepreg laminate by evacuation. After that, the adhesive is cured under pressure and heat in an autoclave to obtain a molded product having a predetermined shape.

[Problems to be solved by the invention]

In such a method of forming a composite material, the thickness of the prepreg laminate changes in the course of the curing reaction, and in particular, there is a disadvantage that the thickness of the corner portion tends to be thinner than the other portions. .

Recently, structural members requiring heat resistance have been molded using a thermosetting resin such as a polyimide resin. In order to form this kind of composite material with good internal quality, it is necessary to make the ratio of the reinforcing fibers contained in the composite material and the fiber volume content _Vf appropriate, but this control is a difficult point. That is, since the molding temperature of this type of composite material exceeds 300 ° C., there is a problem in the heat resistance of the member for controlling the outflow amount of the resin.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a method of forming a composite material capable of forming a molded product having excellent dimensional accuracy and internal quality even at a high molding temperature. It is another object of the present invention to provide a molding method for a molding die used in this molding method.

[Means for solving the problem]

In order to achieve the above object, the present invention covers a permeable sheet on a prepreg laminate, places a metal sheet having a plurality of holes thereon and a shape corresponding to a molded article, and places the metal sheet on the metal sheet. The method is characterized in that a vacuum bag film is placed over the inside, vacuum suction is performed on the inside thereof, and the prepreg is heated and pressurized in an autoclave while pressurizing the prepreg, thereby curing the prepreg laminate.

The present invention also provides a metal sheet having a plurality of holes on a laminate of prepregs mounted on a mandrel on a surface plate, and a vacuum bag film placed on the metal sheet, The inside of the bag film is subjected to vacuum suction, and the thin metal plate is processed into a molding die.

(Operation)

ADVANTAGE OF THE INVENTION According to this invention, while a metal thin plate follows the thickness change at the time of hardening of a prepreg laminated body, the pressure applied to a prepreg laminated body is made uniform. Further, the holes of the metal thin plate serve to pass gas generated during the curing reaction and excess resin.

Further, according to the present invention, a thin metal plate is easily formed as a forming die that conforms to a prepreg laminate by vacuum pressure.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a surface plate.
Is provided with a mandrel 2 for obtaining the shape and dimensions inside the molded product, and a suction port 3 is provided.
A vacuum circuit (not shown) is connected to the suction port 3.

Therefore, first, as shown in FIG. 1 (a), a glass cloth 4 is put on the mandrel 2 as a breathable sheet, and a prepreg 5 of a polyimide resin is divided by the required number of sheets through the glass cloth 4. Stack one by one. Furthermore, after the glass cloth 4 is stacked on the laminated prepreg 5, a thin metal plate, in this embodiment, a thin plate having a thickness of 0.3 to 0.6 mm made of an aluminum alloy is stacked, and the thin plate 6 is stacked. Mold into a mold. As shown in FIG. 3, the thin plate 6 has holes 7 formed with a predetermined hole density, and the hole diameter and hole density of the holes 7 are set according to the shape of the molded product, molding conditions, and the like. Things. The thin plate 6 is coated with, for example, a silicone-based release agent before molding. In addition, the shape of the thin plate 6 before processing is a box shape developed (FIG. 4 (a)), or a fan-shaped thin plate 6 joined to form a second half spherical shape (FIG. 4 (b)). Various variations are possible according to the shape of the molded article.

Next, the vacuum bag film 8 is set on the platen 1 so as to cover the whole of the thin plate 6, and the airtightness inside the vacuum back film 8 is secured by the sealant 9.

As shown in FIG. 1 (b), when the degree of vacuum in the space 10 inside the vacuum bag film 8 increases due to the vacuum suction from the suction port 3, the thin plate 6 becomes
It is bent and molded as a mold.

Next, a method of forming a composite material using the thin plate 6 formed as described above will be described.

Similarly to the above, as shown in FIG. 2 (a), the mandrel 2 was overlaid in the order of glass cloth 4, prepreg 5, glass cloth 4, thin plate 6, and glass cloth 4 and covered with the vacuum bag film 8. Thereafter, vacuum suction is performed from the suction port 3 to apply atmospheric pressure to the prepreg 5 via the thin plate 6, and the shape of the prepreg 5 is adjusted between the mandrel 2 and the thin plate 6.

Next, the prepreg 5 is pressurized and heated in an autoclave and molded (FIG. 2 (b)). At this time, heating temperature 32
The molding was performed under the molding conditions of 0 ° C. and a pressure of 14 atm.

During the curing, a uniform pressure is applied to the prepreg 5 via the thin plate 6, and since the material of the thin plate 6 is a soft aluminum alloy, the thin plate 6 fits into the corners of the laminated prepreg 5 and is cured by adhesive. Since the change in the thickness of the prepreg 5 can be easily followed, it is possible to prevent the thickness of the prepreg 5 from being defective.

On the other hand, the gas generated in the process of curing the prepreg 5 is exhausted through the holes 7 of the thin plate 6, and the generation of voids due to the residual gas can be prevented.

Also, the excess resin flows out through the holes 7 of the thin plate 6 to the outside, but the amount of the outflow depends on the hole diameter and the hole density of the holes 7 of the thin plate 6.
The value of the fiber volume content _Vf can be controlled to an appropriate value. In fact, the molding conditions described above, the preferred pore diameter of the hole 7 of the thin plate 6 is 1.0Mm～1.8Mm, range pore density 0.5-1 pieces per 1 cm ² is in keeping appropriate values of the fiber volume content ratio V _f Met.

In this manner, the thin plate 6 itself has heat resistance even at a molding temperature of 300 ° C. generally required for molding a polyimide resin, and can be widely applied to various composite materials.

〔The invention's effect〕

As is clear from the above description, according to the present invention, since a thin metal plate with a hole is used as a mold,
By setting the dimensional accuracy and the fiber volume content _Vf to appropriate values, it is possible to mold a molded article having excellent internal quality even at a high temperature.

In addition, the above-mentioned thin plate has effects such as being able to be easily formed in a molding process of a molded product by vacuum pressure so as to conform to a prepreg.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the steps of a method for forming a composite material mold according to the present invention, FIG. 2 is an explanatory view showing steps of a method for forming a composite material according to the present invention, and FIG. FIG. 4 is a perspective view showing a modified example of a thin plate used as a molding die. 1 ... surface plate, 2 ... mandrel, 3 ... suction port, 4 ...
Glass cloth, 5: prepreg, 6: thin plate, 7:
Holes, 8 ... vacuum bag film, 9 ... sealant.

Claims (2)

(57) [Claims] 1. A method of molding a composite material, wherein a vacuum bag film is put on a laminate of prepregs, the inside of the vacuum bag film is vacuum-evacuated, and the laminate is pressurized and heated to be cured in an autoclave. A permeable sheet is placed on the laminate of prepregs, a thin metal plate having a plurality of holes and having a shape corresponding to a molded product is placed thereon, and a vacuum bag film is placed on the thin metal plate, and the inside of the thin metal plate is evacuated. And heating the prepreg in an autoclave while applying pressure to the prepreg, thereby curing the prepreg laminate. 2. A metal thin plate having a plurality of holes is placed on a prepreg laminated body placed on a mandrel on a surface plate, and a vacuum bag film is put on the metal thin plate.
A method of forming a composite material forming die, wherein the inside of the vacuum bag film is vacuum-evacuated and the thin metal plate is processed into a forming die.