JP2013059950A - Core body for composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core body for a composite material capable of reducing its weight while employing a resin transfer molding method.SOLUTION: The core body 13 in use for manufacturing a sandwitch panel 11 by the resin transfer molding method has a honeycomb structure 14. Each cell 14a of the honeycomb structure 14 is filled with a closed cell foam 15.

Description

  The present invention relates to a composite material core having a honeycomb structure.

  In the field of transportation equipment such as aircraft and ships, a composite material having a core in a hollow portion is used as a light material having high rigidity. As this composite material, for example, there is a material (sandwich panel) in which a honeycomb structure as a core is interposed between a pair of upper and lower skin materials (for example, a laminate of fiber reinforced fabrics) (for example, Patent Documents). 1). In such a sandwich panel, there is autoclave molding as a method for integrating the honeycomb structure with the skin material. In this autoclave molding, an adhesive layer of a thermosetting resin is interposed between a honeycomb structure and a prepreg for forming a skin material, and the prepreg is thermoset by an autoclave to make a skin made of fiber reinforced composite material. At the same time as forming the material, it is integrated with the honeycomb structure.

  However, in the method of manufacturing a sandwich panel by heating and pressing the prepreg in an autoclave to integrate the skin material and the honeycomb structure, an expensive autoclave is required. There is a risk of damage.

  Therefore, there is a resin transfer molding method (RTM method) as a method for producing a composite material by a method other than autoclave molding. In this RTM method, a skin material made of fiber material and a honeycomb structure are placed in a mold, and a resin is injected into the mold and the skin material is impregnated with the resin to form a composite material. Manufactured.

JP 2006-289646 A

  However, when a composite material is manufactured by the RTM method, the injected resin passes through the skin material and enters and accumulates in the cells (small chambers) of the honeycomb structure, increasing the weight of the honeycomb structure. There is a problem that the weight of the composite material increases.

  An object of the present invention is to provide a composite material core that can be reduced in weight while employing the resin transfer molding method.

  In order to solve the above problems, the present invention provides a core of a composite material having a honeycomb structure, which is used when a composite material is manufactured by a resin transfer molding method using a matrix resin, the honeycomb structure Each cell of the body is filled with a foam which is in the form of closed cells in which bubbles are independently formed at least outside.

  According to this, when a composite material is manufactured by the resin transfer molding method, even if the matrix resin tries to enter the cells of the honeycomb structure, the amount of the matrix resin entering the cells by the foam can be reduced. The core body can be reduced in weight.

  In addition, a skin material, which is an aggregate of fiber bundles, is integrated with the open ends of the cells in the honeycomb structure, and the foam has at least an end surface facing the skin material formed in the form of closed cells. May be.

  According to this, at the end surface facing the skin material in the foam, the bubbles are not connected to each other, and each of the bubbles is independent. For this reason, even if the matrix resin flows toward the foam, the matrix resin only contacts the end face of the foam and does not enter each cell.

In the foam, the bubbles may be formed roughly toward the center, and the bubbles may be formed more densely from the center to the surface side.
According to this, at the end face of the foam facing the skin material, it is possible to further prevent the resin from entering each cell, and to contribute to weight reduction at the center side of the foam.

  According to the present invention, it is possible to reduce the weight while employing the resin transfer molding method.

The disassembled perspective view which shows the sandwich panel of embodiment. (A) is sectional drawing which shows the sandwich panel of embodiment, (b) is a figure which expands and shows the inside of the cell of a honeycomb structure. (A) is a figure which shows the state which has arrange | positioned the honeycomb structure on the support plate, (b) is a figure which shows the state which has arrange | positioned the cover plate on the honeycomb structure, and inject | poured resin in each cell, (c) Is a diagram showing the core body, (d) is a diagram showing a state in which the reinforcing fiber fabric and the core body are arranged in the mold.

Hereinafter, an embodiment in which the core of the composite material of the present invention is embodied as a core of a sandwich panel will be described with reference to FIGS.
As shown in FIG. 1, the sandwich panel 11 includes a skin material 12 made of an aggregate of fiber bundles (unidirectional material, woven fabric, or a laminate thereof), and a core interposed between the skin materials 12. The body 13 is formed integrally. The skin material 12 is made of inorganic fibers such as carbon fibers, glass fibers, ceramic fibers or the like, or high-strength, high-modulus organic fibers such as aramid fibers, poly-p-phenylenebenzobisoxazole fibers, and ultrahigh molecular weight polyethylene fibers. It is composed of a formed reinforcing fiber assembly (fiber material). As the reinforcing fiber assembly, for example, a unidirectional material in which fibers are aligned in the X direction, a fabric in which the fibers are arranged in the X and Y directions, and the like are used. A predetermined number is used.

  The core 13 is composed of a honeycomb structure 14 and a foam 15 filled in a hexagonal cell 14a (small chamber) of the honeycomb structure 14. The honeycomb structure 14 is an aggregate of cells 14a having the same shape, and the cells 14a may be OX, flex, bisecto, feather cell, etc. in addition to hexagons.

  The foam 15 filled in each cell 14a has a high expansion ratio, and the expansion ratio is preferably set to 5 to 20 times. This is because the higher the foaming ratio, the higher the bubble density of the foam 15 and the lighter weight of the foam 15 is achieved. As shown in FIGS. 2 (a) and 2 (b), in the foam 15, each bubble is independently formed and the bubbles are not connected. That is, the foam 15 is a closed foam formed of closed cells. In the present embodiment, closed cells are formed over the entire foam 15. In the foam 15, bubbles are formed more coarsely toward the center, and bubbles are formed closer to the inner surface of each cell 14 a from the center and toward the end surface (surface) side facing each skin material 12. .

Next, the manufacturing method of the core 13 and the sandwich panel 11 will be described.
First, the manufacturing method of the core body 13 is demonstrated. As shown in FIG. 3 (a), the honeycomb structure 14 is placed on the support plate 21, and then the cover plate 22 is placed on the honeycomb structure 14 as shown in FIG. 3 (b). . In addition, the inlet 22a is formed in the cover plate 22 in the position corresponding to each cell 14a of the honeycomb structure 14. And the material of the molten foam 15 is inject | poured in each cell 14a from the injection port 22a. Thereafter, the inlet 22 a is closed, and the material of the foam 15 is heated and foamed through the lid plate 22. Then, as shown in FIG. 3C, the core body 13 in which the cells 15a of the honeycomb structure 14 are filled with the foam 15 is manufactured.

  Next, the manufacturing method of the sandwich panel 11 using the core body 13 as a base material is demonstrated. The sandwich panel 11 is manufactured by a resin transfer molding method (RTM method). Specifically, as shown in FIG. 3 (d), a reinforcing fiber fabric 12 a as a reinforcing fiber assembly as a material of the skin material 12 is disposed in the cavity 31 of the mold 30, and the reinforcing fiber fabric is provided. The core body 13 is disposed between 12a. Then, when the matrix resin is injected into the cavity 31 from the injection port 30a of the mold 30 and the reinforcing fiber fabric 12a is impregnated and cured with the matrix resin, the skin material 12 is formed, and the core material 13 is formed by the skin material 12. The sandwich panel 11 sandwiched is manufactured. As the matrix resin, for example, a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, a phenol resin, or a vinyl ester resin, or a thermoplastic resin such as nylon or ABS resin is used. A mixed resin of a thermosetting resin and a thermoplastic resin can also be used.

Next, the operation of the core body 13 and the sandwich panel 11 will be described.
As shown in FIGS. 1 and 2, in the core body 13 and the sandwich panel 11, the open ends of the cells 14 a in the honeycomb structure 14 and the skin material 12 are joined by the matrix resin being cured and foamed. In the body 15, the end surface facing the skin material 12 and the skin material 12 are bonded together by the matrix resin being cured.

According to the above embodiment, the following effects can be obtained.
(1) The core body 13 of the sandwich panel 11 is composed of a honeycomb structure 14 and a closed-cell foam 15 filled in each cell 14 a of the honeycomb structure 14. For this reason, when manufacturing the sandwich panel 11 by the RTM method by sandwiching the core body 13 between the reinforcing fiber fabrics 12a, even if the matrix resin passes through the reinforcing fiber fabrics 12a, the foam 15 enters the cell 14a. The amount of matrix resin can be reduced. Therefore, weight reduction of the sandwich panel 11 can be achieved.

  (2) The foam 15 was filled in the cells 14 a of the honeycomb structure 14 in the core 13. And the joining site | part to the skin material 12 of the core 13 becomes not only the opening end of the honeycomb structure 14, but the end surface of the foam 15, and it becomes joining by surface contact. For this reason, compared with the case where the joining part of the core body 13 and the skin material 12 is only the open end (joining by line contact) of the honeycomb structure 14, the joining area of the core body 13 and the skin material 12 is increased. Thus, the reliability related to the bonding between the core body 13 and the skin material 12 is improved.

  (3) The foam 15 is an independent foam formed of closed cells, and a large number of bubbles are independent and are not connected to one. For this reason, in the foam 15, the matrix resin is prevented from entering the inside of the foam 15 through the bubbles. As a result, the amount of the matrix resin that enters the honeycomb structure 14 can be minimized, and an increase in the weight of the core body 13 and thus the sandwich panel 11 can be suppressed.

  (4) In the foam 15, bubbles are formed more coarsely toward the center thereof, and bubbles are formed closer to the inner surface of each cell 14 a and closer to the end surface facing each skin material 12. For this reason, at the end surface facing the skin material 12, it is possible to contribute to weight reduction on the center side of the foam 15 while suppressing the amount of the matrix resin entering the bubbles.

  (5) The sandwich panel 11 is manufactured by the RTM method. For this reason, unlike the case where the sandwich panel 11 is manufactured by autoclave molding, a device such as an expensive autoclave is not required, and the sandwich panel 11 can be manufactured at low cost.

  (6) The foam 15 has a high expansion ratio of 5 to 20 times. For this reason, the foam 15 can be filled in the entire cell 14a of the honeycomb structure 14 to reduce the density and contribute to weight reduction while suppressing the penetration of the matrix resin into the cell 14a.

  (7) In addition to the honeycomb structure 14, the core body 13 is filled with the foam 15 in the cell 14a. For this reason, the strength of the sandwich panel 11 can be ensured by both the honeycomb structure 14 and the foam 15, and the strength of the sandwich panel 11 can be increased as compared with the case where the core body 13 is only the honeycomb structure 14. it can.

In addition, you may change the said embodiment as follows.
In the embodiment, the foam 15 is embodied such that the bubbles are formed more coarsely toward the center and the bubbles are formed more densely from the center to the surface side, but the present invention is not limited thereto. The bubbles may be uniformly formed over the entire foam 15, or the bubbles may be randomly formed over the entire foam 15.

  In the embodiment, the entire foam body 15 is closed cells, but in order to suppress the matrix resin from entering the foam body 15, even if only the end surface facing the skin material 12 is closed cells. Good.

  The matrix resin is not limited to a thermosetting resin, and for example, a thermoplastic resin such as polyamide, polybutylene terephthalate, polycarbonate, polyoxymethylene, or polyphenylene ether may be used.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(B) The foaming ratio of the foam is 5 to 20 times. The core of the composite material according to any one of claims 1 to 3.

  (B) The core of the composite material according to claim 2 or 3, wherein the skin material is joined to an end face of the foam that faces the skin material.

  DESCRIPTION OF SYMBOLS 11 ... Sandwich panel as composite material, 12 ... Skin material, 12a ... Reinforcing fiber fabric as an aggregate of fiber bundles, 13 ... Core body, 14 ... Honeycomb structure, 14a ... Cell, 15 ... Foam.

Claims (3)

A matrix resin, which is used when a composite material is manufactured by a resin transfer molding method using a matrix resin and has a honeycomb structure,
A core of a composite material in which each cell of the honeycomb structure is filled with a foam that is in the form of closed cells in which bubbles are independently formed at least outside.   A skin material, which is an aggregate of fiber bundles, is integrated with an opening end of the cell in the honeycomb structure, and at least an end surface of the foam facing the skin material is formed in the closed cell shape. Item 2. A core of the composite material according to Item 1.   The core of the composite material according to claim 1 or 2, wherein the foam is formed so that the bubbles are formed more coarsely toward the center and the bubbles are formed closer to the surface side from the center.

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