JPS60234833A - Composite material structure and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a structure made of a resin-based composite material obtained by impregnating reinforcing fibers with a resin and curing the same, and a method for manufacturing the same.

(Prior art) Conventionally, as a method for manufacturing structures made of composite materials in which reinforcing fibers such as glass fibers, organic fibers, and carbon fibers are impregnated and cured with resins such as epoxy resins, polyester resins, and polyimide resins, Patent No. 3, 7/J, 7
No. 33 and Tokukai Sho! ;0-/Ako? There are some that have been disclosed in Publication No. g, etc. All of these known methods are useful for manufacturing products in which the dimensional accuracy of the outer surface of the structure has a significant effect on performance, such as aerodynamic machines such as aircraft wings, various propellers, rotor blades, etc. . The basic means of this known method is to place a molded article made of a composite material along the molding surface of a closed mold having a molding surface that can give the required external dimensions, and to A bag-shaped inner mold is placed inside the mold, and pressurized gas is introduced into the inner mold to press the molded object from the inside against the molding surface of the mold while heating and molding it.

By the way, aerodynamic machines to which this method is mainly applied are:
Since it has a flat elliptical shape, there is at least 1 piece inside.
It is necessary to provide several partition walls. Therefore, in the above method, at least two inner molds are required, and a partition wall is placed between the two inner molds. An example of using this number of inner molds is disclosed in Japanese Patent Application Laid-open No. 3377, ltlI-/, published by Sho. However, in this known method, there is a risk that the bag used as the inner mold may become suspended in the air at the corner of the partition wall and burst due to internal pressure, and the manufacturing process is labor-intensive due to the large number of inner molds. This will cause the price to rise. In addition, in a structure that uses a honeycomb core on the inner surface of the outer skin structure, there is a risk that resin may enter the core and cause the center of gravity to shift, causing flutter.Moisture may also enter the inside of the honeycomb core, causing may freeze and cause the bond to peel. Furthermore, during manufacturing, there is a risk that the partition walls placed between the inner molds may be misaligned or tilted.

To solve this problem, instead of the inner mold, a low-density core material such as honeycomb or foamed resin, which is formed slightly larger than the finished size, is inserted between the outer skin structural members and a closed mold is used. A method has also been proposed in which molding is carried out while compressing the material to some extent. However, in this method, the core material needs to be filled inside without any gaps, so the dimensional accuracy of the core material needs to be high, and the cross-sectional shape cannot be changed in a complicated manner. Further, when a core material having a honeycomb structure is used, there is a problem in that pressure cannot be uniformly applied to the outer shell structure from within, resulting in a low-quality product with many bubbles.

(Object of the Invention) An object of the present invention is to provide a composite material structure that requires only one inner mold and can be easily manufactured without fear of bursting of the inner mold, and a method for manufacturing the same.

Furthermore, another object of the present invention is to provide a composite material structure that does not cause the center of gravity to shift due to resin entering the honeycomb even when a honeycomb structure is used as the core material. be.

(Structure of the invention) In order to achieve the above object, the present invention has the following configuration.

That is, the composite material structure according to the present invention includes a skin structure made of a composite material in which reinforcing fibers are impregnated with resin, a thin layer continuous in a closed cross section adhered to the inner surface of the skin structure, and a thin layer of the thin layer. and a core material disposed inside and adhered to the thin layer, and the core material may be a low-density material such as a honeycomb structure or a hollow foam.

Further, in another aspect of the present invention, the composite structure includes:
A skin structure made of a composite material made of reinforcing fibers impregnated with resin and thickened so that the front edge forms a main girder, and a thin layer continuous in a closed cross section adhered to the inner surface of the skin structure. , a low-density core material disposed inside the thin layer and having upper and lower surfaces adhered to the thin layer, and is formed so as to have an airfoil-shaped cross section as a whole. In a preferred structure of this aspect of the present invention, an inclined surface is formed on the inner surface of the skin structure between the thick part forming the main girder and the rear edge, and the front part of the core material is arranged such that the front part follows the inclined surface. The shape is such that the front part is tapered towards the front, and the rear part is tapered towards the rear. This structure can prevent the core material from shifting due to pressure during manufacturing.

Furthermore, the method for manufacturing a composite structure according to the present invention includes: along the molding surface of a rigid mold having a molding surface of a desired shape;
An outer skin structure material made of a composite material made of reinforcing fibers impregnated with resin is arranged, and an inner mold K having a closed cross-section hollow shape made of a thin film of a material that is adhesive to the composite material is adhesively bonded to the inner mold. A core material encapsulated therein is placed within the outer skin structure material, and pressurized gas is introduced into the inner mold while applying compressive force to the core material using the mold to mold the outer skin structure from the inside. The outer shell structure material, inner mold, and core material are integrally molded by pressing them onto the molding surface of the mold and heating them at the same time. As the core material, it is desirable to use a breathable, low-density material. For example, Nomex honeycomb or open-cell foamed resin may be used.

(Effect of the invention) In the present invention, on the inner surface of the outer skin structure made of composite material,
Since a continuous thin film with a closed cross section is adhered and a core material is placed inside the thin film, the thin film can be used as an inner mold during manufacturing, and only seven inner molds are required. therefore,
This prevents the problem of the thin film floating in the air at the corners during manufacturing and bursting due to internal pressure, and also eliminates the possibility that the resin contained in the outer skin structure will enter the core material and cause a change in the center of gravity.

Furthermore, since there is no need to use a partition wall in the center, there is no need to worry about displacement or inclination of the partition wall.

Furthermore, the core material can be inserted only where it is needed, and there is no need to increase its dimensional accuracy.

(Description of Examples) First Example (FIG. 1) As shown in FIG. 1, an upper mold 1 and a lower mold 2 having molding surfaces 1a and 2a, respectively, are prepared. Next, the bodies 3 and 4 to be molded to form the outer skin structure are formed from a composite material made of reinforcing fibers impregnated with resin, and the bodies 3.4 to be molded are each molded on the molding surface 1a of the upper die 1.2.

2a. This example concerns the manufacture of rotor blades for rotorcraft, and the object to be formed 3.4 is:
A thick wall portion 3a+4a serving as a main beam is provided in a portion corresponding to the front edge of the blade cross section. Further, on the front edge, a peg 5 for adjusting the center of gravity position is arranged so as to be sandwiched between the objects to be formed 3 and 4.

Further, an inner mold 6 is prepared in which a tube or sheet made of a thin film adhesive to the composite material is made into a tube shape, and a core material 7 having a honeycomb structure is placed within this inner mold 6.

The core material 7 is arranged with the cells facing up and down, and the dimension in the vertical direction, that is, the thickness is slightly thicker than the thickness of the core material 7 when completed. An adhesive 8 is applied to the upper and lower surfaces of the core material 7.

The core material 7 contained in the inner mold 6 is placed between the upper and lower molded objects 3.4, and the upper mold 1 and the lower mold 2 are closed. Next, pressurized gas is introduced into the inner mold 6, and the molded objects 3, 4 are pressed against the molding surface 1a of the mold by the pressure.

Molding is performed by heating while pressing against 2a. The inner mold 6 is bonded to the molded objects 3 and 4 while molding them. Moreover, since the core material 7 is somewhat thick, it is slightly crushed in the compression direction by the pressure applied from the mold 1.2, and is adhered to the inner mold 6 on the upper and lower surfaces. The core material 7 is preferably one that has air permeability between cells, such as Nomex honeycomb, and if this type of honeycomb is used,
It is possible to prevent the cells from being crushed by the pressure introduced into the inner mold 6. When using a foamed resin body as the core material 7, it is preferable to use one with open cells.

Since the inner mold 6 is made of a thin film, the molded objects 3 and 4 are molded by internal pressure.
It goes without saying that the pressure can be applied uniformly, and that the inner mold will not be left floating in the corner, unlike when a partition is placed between them, and there will be no risk of rupture. A highly homogeneous structure can be obtained. Moreover, the core material 7 is
They can be placed only where necessary in view of the strength and rigidity of the structure, and there is no need to increase the processing accuracy of the core material 7.

Further, the resin of the molded objects 3 and 4 does not enter the core material 7, and the center of gravity does not change during manufacturing. Furthermore, since the single core material 7 is housed inside the inner mold 6,
There is no fear that moisture will enter the core material 7 during use. In this example, the object to be formed 3.4 has slopes 3b, 4b formed on the inner surface between the thick parts 3a, 4a and the rear edge, and the core material 7 is formed on the slopes 3b, 4b. Since it has a forward tapered part 7a corresponding to the rear edge and a rearward tapered part 7b corresponding to the rear edge, the core material 7 is moved from the front to the rear during molding due to the pressure from the molds 1 and 2. No more displacement.

In this example, a honeycomb structure inner lining 99. ．． 10 are placed,
Furthermore, an inner skin 11.12 is arranged along the inside of the molded bodies 3, 4. Moreover, the width of the core material 7 in the front-rear direction is smaller than that of the previous example. This example has the advantage that the processing of the core material 7 is easier than in the previous example.

Third Embodiment (Fig. 3) In this example, the core material disposed in the inner mold 6 is divided into a high-density front part 14 and a low-density rear edge part 15. The rear edge is in contact with 5! The adhesive 16 is used for adhesion.

In this example, the torsional rigidity of the whole can be increased by directing the shear flow generated in the thick parts 3a, 4a of the outer skin structure constituted by the molded bodies 3゜4 to the high-density front edge part 14, Accordingly, the weight of the rear edge portion 15 can be reduced.
It has the advantage of

Embodiment 2 (FIG. 9) In this example, the molded bodies 23 and 24 serving as the outer skin structure do not have a thick wall portion, and furthermore, a bell for adjusting the center of gravity at the leading edge is not used. Further, the dimensions of the core material 7 are smaller than those in FIG.

The structure of this example is suitable for helicopter tail rotors, fans, etc.

[Brief explanation of the drawing]

1, 2, 3, and 1I are cross-sectional views showing different embodiments of the present invention, respectively.

Claims (5)

[Claims] (1) An outer skin structure made of a composite material in which reinforcing fibers are impregnated with a resin, a thin layer that is continuous in a closed cross section and is adhered to the inner surface of the outer skin structure, and the thin layer that is arranged inside the thin layer. A composite structure consisting of a core material bonded to (2) A skin structure made of a composite material made of reinforcing fibers impregnated with resin and thickened so that the leading edge forms the main girder;
It consists of a thin layer that is continuous in a closed cross section and is bonded to the inner surface of the skin structure, and a low-density core material that is placed inside the thin layer and whose upper and lower surfaces are bonded to the thin layer, and the overall structure has an airfoil shape. Composite structure in cross section (3) In the above item 2, a slope is formed on the inner surface of the skin structure between the thick part forming the main girder and the rear edge, and the front part of the core material is arranged such that the front part follows the slope. A composite structure that tapers toward the front and tapers toward the rear at the rear. (4) Along the molding surface of a rigid mold having a molding surface of a desired shape, an outer skin structure material made of a composite material in which reinforcing fibers are impregnated with resin is arranged, and a material having adhesive properties to the composite material is arranged. A core material that can be adhered to the inner mold is enclosed inside a closed-section hollow inner mold made of a thin film of , and is placed in the outer skin structure material and compressed into the core material by the mold. Pressurized gas is introduced into the inner mold while applying force to press the outer skin structure from the inside against the molding surface of the mold, and at the same time, the outer skin structure material, the inner mold, and the core material are integrally molded. Manufacturing method for featured composite structures (5) A method for manufacturing a composite structure in the above item, wherein the core material is made of a breathable low-density material.