JP2007190854A - Method for forming hollow or solid FRP molded product - Google Patents

Abstract

An object of the present invention is to provide a simple molding method of a hollow or solid FRP molded product having an accurate surface both inside and outside.
When forming a hollow or solid FRP molded product using a mold composed of an upper mold, a lower mold, and a core, the core on which the prepreg is wound and laminated is divided into an upper mold and a lower mold. For example, a heat expansion member such as a heat-resistant rubber is disposed in contact with the upper die and / or the lower die, leaving a clearance of 0.2-2 mm, for example, and a heat-resistant rubber is disposed therebetween. A method for forming a hollow or solid FRP molded product comprising fixing a mold with an outer frame and then heating the mold in a heating / curing furnace.
[Selection] Figure 1

Description

The present invention relates to a method for forming a hollow or solid FRP molded product used for industrial use or as a structural member.

Fiber reinforced plastic (FRP) is a thermosetting resin such as unsaturated polyester resin, epoxy resin and polyimide resin, matrix resin of thermoplastic resin such as polyethylene, polypropylene, polyamide, PPS, PEEK, carbon fiber, glass fiber In recent years, it is used in a wide range of fields from the aerospace industry to the general industrial field.

Known methods for forming FRP into a tubular or hollow hollow member include centrifugal molding, pultrusion molding, filament winding molding, internal pressure molding, and the like. Among these methods, the internal pressure molding method (for example, Patent Document 1) is a relatively simple method, in which a cylindrical molding material is disposed in a mold cavity, and this is applied to the gold by applying pressure from the inside of the cylinder. It is a method of heat-curing in a state of being in close contact with the mold, and can be applied regardless of whether the matrix resin is thermosetting or thermoplastic. Is suitable.

In order to form a hollow tubular FRP molded product (hollow member) by the internal pressure molding method, a prepreg is usually used, and an expandable bag or tube is placed inside the prepreg disposed in the hollow tube in the mold cavity. Insert. Next, the bag or tube is inflated with compressed air, etc., pressure is applied from the inside of the mold, the prepreg is pressed against the inner wall of the mold, and the prepreg is heated and cured in this state to form the pressure bag. It has been. However, in the case of the conventional pressure bag molding method as described above, the outer surface of the hollow member is molded to an accurate surface along the mold, but the inner surface cannot always be molded with sufficient accuracy. was there.
JP-A-6-155595 JP 2003-334835 A

On the other hand, as a simple molding method for obtaining a molded product in which the inner surface of the hollow member is molded into an accurate surface, a core (mandrel or inner mold) is used, and this core (for example, made of aluminum or iron) is used. A method is also known in which a prepreg is wound and laminated, and the wound and laminated prepreg is taped or coated with a heat-shrinkable tape such as polyethylene, polypropylene, and polyester, and then heat-molded in a curing furnace or the like (medium Child taping molding). This method is a convenient method for molding a muffler, a roller and the like, but there is a problem that the accuracy of the outer surface is not good.

An object of the present invention is to provide a simple molding method of a hollow or solid FRP molded product having an accurate surface both inside and outside.

According to the first aspect of the present invention, when a hollow or solid FRP molded product is formed using a mold composed of an upper mold, a lower mold, and a core, a core in which a prepreg is wound and laminated is formed. The upper mold and the lower mold are clamped with a margin of pressing, and a thermal expansion member is arranged in contact with the upper mold and / or the lower mold, and the mold is fixed with an outer frame via the thermal expansion member, Thereafter, the mold is heated in a heating / curing furnace, which is a method for forming a hollow or solid FRP molded product.

The hollow or solid FRP molded product according to claim 1, wherein the upper die and the lower die are clamped leaving a push allowance of 0.2-2 mm. This is a molding method.

The invention according to claim 3 of the present invention is the method for forming a hollow or solid FRP molded product according to claim 1 or 2, wherein the thermal expansion member is a heat-resistant rubber.

According to the present invention, without using a large molding machine or a special molding machine, it is a simple and easy method using a normal curing furnace, a dryer, etc., and is made of a hollow FRP having an accurate surface both inside and outside. Molded articles can be manufactured. In the present invention, if an appropriate core is selected, a solid FRP molded product can be produced by leaving it in the molded body without removing it from the molded body.

In the present invention, the core in which the prepreg is wound and laminated is clamped by leaving the allowance between the upper mold and the lower mold of the mold, and the thermal expansion member is disposed in contact with the upper mold and / or the lower mold. The mold is fixed with an outer frame through the thermal expansion member, and then the mold is heated in a heating / curing furnace to form a hollow or solid FRP molded product. There is no restriction | limiting in particular as a real FRP molded article, As long as it is a hollow or solid member, what kind of shape may be sufficient as it.

The mold for shaping the outer surface of the FRP molded product used in the present invention may be a metal mold such as steel or aluminum alloy, or an FRP mold such as glass fiber. It doesn't matter. The shape and material of the inner surface shaping core (mandrel or inner mold) in the present invention are not particularly limited. When the core is removed after molding, a hollow FRP molded product is obtained. Depending on the purpose and application of the molded product, the core may be left as it is. For example, when hard foamed urethane, vinyl chloride, or polystyrene is used as the core, a solid FRP molded product having the core as the core material can be obtained.

In the present invention, first, the core on which the prepreg is wound and laminated is clamped with the upper mold and the lower mold of the mold leaving the allowance. At this time, it is preferable that the upper die and the lower die are clamped with a push margin of 0.2-2 mm. In the case of 0.2 mm or less, the effect of the thermal expansion member is hardly exhibited by subsequent heating, and in the case of 2 mm or more, it is difficult to fix with the outer frame.

In the present invention, the thermal expansion member is further disposed in contact with the upper mold and / or the lower mold, and the mold is fixed by the outer frame via the thermal expansion member. The thermal expansion member may be anything as long as it is heat resistant and has a property of expanding by heat. Preference is given to heat-resistant rubber. The material and shape of the outer frame are not particularly limited, and any outer frame can be used. Further, the fixing method may be any method or means such as a method of screwing using a bolt or a method using a bolt and a nut.

Next, in the present invention, the mold fixed by the outer frame via the thermal expansion member is heated in a heating / curing furnace. As the heating / curing furnace, a normal curing furnace, a dryer or the like is used. The heating and curing conditions are usually 90 to 180 ° C. for 1 to 2 hours.

The fiber reinforced plastic (FRP) of the present invention is a composite material obtained by impregnating and curing a matrix resin such as a thermosetting resin or a thermoplastic resin in a fiber reinforcing material, but is used in the present invention. There are no particular restrictions on fiber reinforcements and matrix resins. Examples of the fiber reinforcing material include carbon fiber, glass fiber, aramid fiber, boron fiber, and metal fiber. Preferred is carbon fiber.

Examples of the thermosetting resin include epoxy resins, unsaturated polyester resins, phenol resins, vinyl ester resins, cyanate ester resins, urethane acrylate resins, phenoxy resins, alkyd resins, urethane resins, maleimide resins and cyanate ester resins. There are resins selected from prepolymerized resins. These can also be used as one type or a mixture of two or more types. Examples of thermoplastic resins include polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplastic polyimide, and polyamideimide. is there. Two or more of these resins may be used in combination.

The fiber reinforcement is usually composed of warp and weft such as plain weave, twill weave, satin weave, etc., and the fiber bundle is aligned in one direction into a sheet shape, and this is uniaxially stitched with stitch threads in the perpendicular direction It is used in the form of a woven fabric, a multi-axis woven fabric in which a plurality of sheet-like materials arranged in one direction are stacked at different angles and stitched with a stitch thread in a perpendicular direction. The prepreg of the present invention is a molded intermediate material in which a fiber reinforcing material is impregnated with a matrix resin such as a thermosetting resin or a thermoplastic resin to adjust the fluidity and adhesiveness to improve the handling property. The resin content is usually 30 to 70% by weight.

An example of the molding method according to the present invention will be described with reference to the drawings. 1 in FIG. 1 (cross section) is an upper mold of a mold for shaping the outer surface of an FRP molded product, 2 is a lower mold, 3 is a core, 4 is wound and laminated on the core The arranged prepregs, 5 are thermal expansion members arranged in contact with the upper mold, and 6 is an outer frame. FIG. 1 shows a state in which the mold is clamped with a push allowance 7, and this mold is fixed by an outer frame 6 via a thermal expansion member 5. For example, as shown in FIG. 1, the bolt 8 and the nut 9 can be used for fixing. Although only one location is fixed in FIG. 1, several locations may be fixed as required. When a mold fixed with an outer frame via a thermal expansion member is heated in a heating / curing furnace, the thermal expansion member expands to completely close the mold, and FRP molding with an accurate surface both inside and outside Goods are obtained. Hereinafter, the present invention will be described more specifically with reference to examples.

As a carbon fiber prepreg, a plain fabric (W-3101, manufactured by Toho Tenax Co., Ltd.) using a carbon fiber HTA3K (manufactured by Toho Tenax Co., Ltd., general-purpose grade carbon fiber, 3000 filaments) as a warp weft was impregnated with a general-purpose epoxy resin. What was used (resin content: 40%). 5 layers of this prepreg are stacked so that the lamination pattern is (0/90), (± 45), (30/120), (± 45), (0/90), and is shown in FIG. 1 (cross section). The core was wound and laminated as shown.

Then, as shown in FIG. 1, the core was clamped with an upper mold and a lower mold, and heat-resistant silicone rubber was arranged in contact with the upper mold, and the whole was fixed with an outer frame. Then, the metal mold | die fixed with the outer frame was put into the heating and hardening furnace, and it heated at 120-130 degreeC for 1.5 hours. After the mold was taken out and cooled, the upper mold, the lower mold, and the core were removed from the mold. As a result, an FRP molded product in which the inner and outer surfaces were accurately molded was obtained.

It is a figure (sectional drawing) for demonstrating the shaping | molding method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper mold for outer surface shaping mold 2 Lower mold for outer surface shaping mold 3 Core 4 Prepreg 5 Thermal expansion member 6 Outer frame 7 Push allowance of upper mold and lower mold 8 Bolt 9 nut

Claims (3)

When forming a hollow or solid FRP molded product using a mold consisting of an upper mold, a lower mold, and a core, the core with the prepreg wound and laminated is left with a press margin between the upper mold and the lower mold. Then, the thermal expansion member is placed in contact with the upper mold and / or the lower mold, and the mold is fixed with the outer frame through the thermal expansion member, and then the mold is heated in a heating / curing furnace. A method for forming a hollow or solid FRP molded product. 2. The method for forming a hollow or solid FRP molded product according to claim 1, wherein the upper die and the lower die are clamped leaving a press margin of 0.2-2 mm. The method for molding a hollow or solid FRP molded product according to claim 1 or 2, wherein the thermal expansion member is a heat-resistant rubber.

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