JP2005231132A - Hermetically closed molded product manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hermetically closed molded product manufacturing method capable of manufacturing a fiber reinforced resin composite material of which the inside and outside do not communicate. <P>SOLUTION: In the hermetically closed molded product manufacturing method, prepregs 2 and 4, foamable sheets 6 and 8, and an inside mold 10 following the inside shape of a hollow split mold 100 formed of an upper mold 16 and a lower mold 18 are housed in the hollow split mold so as to go toward the center of the mold from the inner surface thereof to clamp the upper and lower molds and the split mold 100 is subsequently heated not only to foam the foamable sheets 6 and 8 but also to cure the prepregs 2 and 4. As the inside mold 10, a molded foam comprising a foamed resin is preferably used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention manufactures a hermetic molded product in which an interior and an exterior are hermetically formed by utilizing a foaming pressure of a foam sheet disposed between a prepreg laid on an inner surface of a hollow mold and an internal mold. Regarding the method.

  The fiber reinforced resin composite material is lightweight and has high rigidity, and is used for materials for sports equipment such as golf shafts, fishing rods, tennis rackets, automobiles, and aircraft.

  As a method for producing a hollow fiber-reinforced resin composite material using a thermosetting resin, a filament winding method or a bag molding method is generally used.

  The filament winding method is a method of manufacturing a molded product by winding reinforcing fibers impregnated with a thermosetting resin around a mandrel, curing the resin by heating, and then pulling out the mandrel (for example, see Patent Document 1). Hollow molded products that can be manufactured by the filament winding method are limited to simple shapes such as pipes, and hollow molded products cannot be manufactured directly.

In the bag forming method, a prepreg is laid on the inner surface of a hollow mold cavity, and the expansion bag disposed inside the prepreg is deformed by filling it with fluid to bring the prepreg into close contact with the inner surface of the mold and heating in that state. This is a method of curing the prepreg (see, for example, Patent Document 2). The bag molding method can produce various shapes of composite materials by changing the shape of the mold, and is a general method for producing a hollow composite material.
JP 2000-301612 A (Claim 1) JP-A-5-329856 (Claim 1)

  The fiber reinforced resin composite material may require a hollow molded product having a shape in which the space between the inside and the outside is completely airtight depending on the application. For example, aircraft members are required to have high strength in addition to being lightweight, but a sealed shape with the inside closed is advantageous in terms of strength.

  In the bag forming method, it is necessary to inflate a bag placed inside the prepreg after the hollow mold is clamped and to inflate it, and it is necessary to provide an inlet for filling the bag with the fluid. For this reason, it is impossible to manufacture a sealed fiber-reinforced resin composite material whose inside is completely closed.

  An object of the present invention is to provide a method for producing a hermetic molded product capable of producing a fiber-reinforced resin composite material having a shape in which an inside and an outside are formed airtight.

  As a result of diligent research, the present inventor has placed a foam sheet made of resin that foams by heating and an internal mold having almost the same shape as the interior space of the mold in place of the conventional bag in the hollow mold. The inventors have found that a hermetic molded product in which the interior and the exterior are hermetically formed can be easily manufactured, and have completed the present invention.

  The present invention for solving the above problems is described below.

  [1] From the inner surface of the hollow split mold toward the center of the mold, the prepreg, the foam sheet, and the internal mold following the internal shape of the split mold are housed in the prepreg, the foam sheet, and the mold is clamped, and then the split mold is heated. A process for producing a hermetic molded product in which the foamed sheet is foamed and the prepreg is cured.

  [2] The method for producing a hermetic molded product according to [1], wherein the shape of the hollow split mold is an airtight shape between the inside and the outside.

  [3] The method for producing a hermetic molded product according to [1], wherein the internal mold is a molded foam made of a foamed resin.

  [4] The method for producing a hermetic molded product according to [1], wherein the internal mold has a volume 0.7 to 0.8 times the internal space shape of the hollow split mold.

  According to the present invention, even if the shape of the molded product is a hermetically sealed shape formed between the inside and the outside which cannot be manufactured by the conventional bag molding method, it is easily made of a fiber reinforced resin composite material. A sealed molded product can be obtained. By using a molded foam made of a foamed resin as the internal mold, it is possible to produce a lightweight and high-strength sealed molded product.

  Hereinafter, the manufacturing method of the hermetic molded product of the present invention will be described with reference to FIG.

  First, the prepregs 2 and 4 are laid on the inner surface of the split mold 100 formed by the upper mold 16 and the lower mold 18 (FIG. 1A). The split mold 100 is a closed hollow mold whose inside has an elliptical cross section and does not communicate with the outside. The prepreg 4 is affixed to the upper die 16 and is cut in alignment with the lower end surface of the upper die 16. On the other hand, the prepreg 2 is attached to the lower mold 18 and has a protruding portion 5 that protrudes upward from the upper end surface of the lower mold 18 and is cut. Examples of the prepregs 2 and 4 include a sheet in which reinforcing fibers such as carbon fibers are aligned in one direction and impregnated with a thermosetting resin such as an epoxy resin.

  Next, the foam sheet 6, the internal mold 10 made of a foam, and the foam sheet 8 are sequentially stacked on the inner surface of the prepreg 2 laid on the lower mold 18 (FIG. 1B). The shape of the internal die 10 is a shape that follows the internal space shape of the split die 100.

  As the foam sheets 6 and 8, a known film can be used without particular limitation as long as it is a resin film that expands and expands when heated. However, the internal mold 10 and the prepregs 2 and 4 made of a foam after cooling can be used. Those that adhere are preferred. Furthermore, the foam sheets 6 and 8 are preferably cured at about 100 to 130 ° C. The expansion ratio of the foamed sheets 6 and 8 by heating is preferably 1.75 to 2.5 times. Examples of the foam sheet that can be preferably used in the present invention include a sheet made of a modified epoxy resin such as Redux 212-NA (manufactured by Ciba Geigy).

  The material of the internal mold 10 made of a foam is a heat-foamed resin, which has a compressive strength and heat resistance to transmit the foaming pressure to the prepreg when the prepreg is pressurized by foaming the foamed sheet in the subsequent process. Any known material can be used as long as it has the following. Examples of the foam that can be preferably used in the present invention include polymethacrylimide hard foams such as Lohacell 31, 51, 71, and 110 (manufactured by Sanwa Trading Co., Ltd.). Since the foam becomes a part of the molded product after molding, it is preferably lightweight.

  Next, after the protruding portion 5 of the prepreg 2 is overlapped with the peripheral edge of the prepreg 4 to close the split mold 100, the split mold 100 is clamped (FIG. 1 (c)). Accordingly, the prepregs 2 and 4, the foam sheets 6 and 8, and the internal mold 10 are accommodated in this order from the inner surface of the split mold 100 toward the center of the mold in the split mold 100. In this state, the entire mold is heated. By heating, the foam sheets 6 and 8 are foamed, and the prepregs 2 and 4 are pressed from the inside of the split mold 100 toward the outside and are in close contact with the inner surface of the split mold 100.

  After the prepregs 2 and 4 are heat-cured, the prepregs 2 and 4 are taken out from the split mold 100 to obtain a sealed molded product 1 (FIG. 1D). The hermetic molded product 1 has a foamed resin layer 14 and an internal mold 10 made of a foam inside a fiber reinforced resin layer 12 formed in a shell shape composed of heat-cured prepregs 2 and 4. The foamed sheets 6 and 8 are foamed by heating to form a foamed resin layer 14, and become an element constituting the sealed molded product 1 together with the internal mold 10.

  As the prepregs 2 and 4, known prepregs can be used without limitation.

  In the above description, the protruding portion 5 is formed on the peripheral edge of the prepreg 2, and the peripheral edge of the prepreg 4 and the protruding portion 5 are overlapped when the mold is clamped to form a sealed molded product. In the case where 8 has adhesiveness, the end portions may be bonded by attaching the peripheral end portions of the prepregs 2 and 4 without providing the protruding portion 5.

  The internal mold 10 made of foam preferably has a volume before molding of about 0.7 to 0.8 times the internal space shape of the split mold 100. In addition, the shape is not particularly limited as long as the entire prepreg can be pressurized from the inside by the foaming pressure of the foam sheet, but it is about 0.85 to 0.95 times the internal space shape of the split mold 100. It is preferable that the scale is similar.

  As the internal mold 10, a foamed resin cut out in accordance with the internal shape of the split mold can be used as it is as a molded foam, but a molded foam preformed by a press can be preferably used.

  The heating temperature when the prepreg is heat-cured is preferably about 100 to 130 ° C.

  Furthermore, although the above example has been described using two divided types, the number of divided types is arbitrary. Moreover, the sectional shape of the split type can also be arbitrary. In the above example, a closed hollow type in which the inside does not communicate with the outside is used as the split type, but it can be used without being limited to the closed hollow type as long as the prepreg can be pressurized by the foaming pressure of the foam sheet. it can. Furthermore, although the foam was used as the internal mold, it is not limited to this and can be composed of any material.

Example 1
A prepreg was laid on the inner surface of a split mold consisting of an upper mold and a lower mold, and one foam sheet (Redux212-NA, manufactured by Ciba-Geigy) was placed on the prepreg. Laminated structure of prepreg is W-3101 / Q-195 (± 45) 1ply / W-3101 / Q-195 (0/90) 1ply (above, manufactured by Toho Tenax Co., Ltd.) ). Thereafter, an internal die (Rohacell 31IG, manufactured by Sanwa Trading Co., Ltd.) was placed in the cavity formed by the split die, and the upper die and the lower die were clamped. The split mold and the molding material were placed in a curing furnace and heated at 80 ° C. for 30 minutes, and then heated at 130 ° C. for 2 hours to heat and cure the prepreg to obtain a rotor blade.

  The top view of the obtained rotor blade is shown in FIG. 2, and the side view is shown in FIG. The rotor blade 20 is a fiber reinforced resin composite material formed in a plate shape having a substantially quadrangular front view, and has a hole 22 for inserting a shaft serving as a rotating shaft on one end side thereof. A sectional view taken along line aa shown in FIG. 2 is shown in FIG. The cross-sectional shape of the rotor blade 20 along the aa line is a streamlined bulge at the center, and includes a foamed resin layer 26 and an internal mold 28 made of a foam inside the fiber reinforced resin layer 24 forming the outermost layer. To do.

  The rotor blade 20 had a maximum length in the direction connecting the rotation center and the rotation tip of 20 cm and a specific gravity of 0.9.

Comparative Example 1
A rotor blade was manufactured in the same manner as in Example 1 except that six foam sheets were laminated and used instead of the internal mold. The specific gravity of the obtained molded product was 1.25.

It is explanatory drawing which shows an example of the manufacturing method of the sealing molded product of this invention. It is a top view which shows the rotor blade manufactured in the Example. FIG. 3 is a side view of the rotor blade shown in FIG. 2. It is sectional drawing of the rotor blade in the aa line shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing molded product 2, 4 Prepreg 5 Protruding part 6, 8 Foam sheet 10 Internal type 12 Fiber reinforced resin layer 14 Foamed resin layer 16 Upper mold | type 18 Lower mold | type 100 Split type

Claims (4)

From the inner surface of the hollow split mold toward the center of the mold, the prepreg, the foam sheet, the internal mold following the internal shape of the split mold is housed in the prepreg, the mold is clamped, and then the split mold is heated to A method for producing a hermetic molded product in which a foamed sheet is foamed and the prepreg is cured. The method for producing a hermetic molded product according to claim 1, wherein the shape of the hollow split mold is a shape in which an interior and an exterior are hermetically formed. The method for producing a hermetic molded product according to claim 1, wherein the internal mold is a molded foam made of a foamed resin. The method for producing a hermetic molded product according to claim 1, wherein the internal mold has a volume 0.7 to 0.8 times the internal space shape of the hollow split mold.

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