JP3000405B2 - Method of forming fiber molded article for fiber reinforced composite member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a fiber molded article for a fiber-reinforced composite member.

[0002]

2. Description of the Related Art Conventionally, as this kind of molding method, there is a method in which a short fiber, for example, a slurry-like molding material in which whiskers are dispersed in a liquid is poured into a mold, and then the liquid is removed and the short fibers are deposited. Are known.

[0003]

However, according to the conventional method, the density of the deposits tends to increase with the removal of the liquid.
There is a problem that the drainage path formed between the short fibers in the sediment decreases and it takes much time to remove the liquid, and as a result, the productivity of the fiber molded body is poor.

[0004] In view of the above, it is an object of the present invention to provide a molding method capable of shortening the liquid removal time and improving the productivity of a fiber molded article.

[0005]

According to the present invention, there is provided a method for forming a fiber molded article for a fiber-reinforced composite member, comprising the steps of: mixing a short fiber and a modified fiber having a plurality of needle-like portions extending from a core portion; Is injected into a mold, and the liquid is removed and the mixed fibers are deposited.

[0006]

1 and 2 show a fiber molded article 1 for a fiber-reinforced composite member obtained according to the present invention. The fiber molded article 1 is composed of a short fiber (including a whisker) 2 and a modified fiber 3 which are substantially more similar. It is formed in a disk shape.

The short fiber 2 has a predetermined length satisfying a relationship of L / D> 1 when the length is L and the diameter is D. In this embodiment, the aluminum borate whisker (9Al ₂ O ₃ .2B ₂ O ₃ whiskers) are used. The length L of this aluminum borate whisker is 10
２０20 μm, and the diameter D is 0.5-3 μm. As the deformed fiber 3, as shown in FIG. 3, a tetrapod shape having a plurality of needles 5 extending from the core portion 4 in the illustrated example, and a zinc oxide whisker (ZnO
Whisker) is used. In this zinc oxide whisker, the length of the needle portion 5 from the core portion 4 is 10 to 100 μm.
m.

[0008] In the fiber molded article 1, the short fibers 2 are dispersed in a random state throughout the fiber molded article 1, and the deformed fibers 3 are substantially uniformly dispersed in the aggregate of the short fibers 2.

Next, a method of forming the fiber molded body 1 will be described.

FIG. 4 shows a molding die 6 used in the present invention. The molding die 6 is slidably fitted into a mold body 8 having a cavity 7 opening upward. A plurality of drain holes 10 are formed on the bottom surface of the cavity of the mold body 8.
The inlets of the drain holes 10 are covered with a filter 11, and the outlet side is connected to a suction pump 12.

First, a mixed fiber composed of the short fibers 2 and the modified fibers 3 is dispersed in a liquid, in this embodiment, water to prepare a slurry-like molding material.

Next, as shown in FIG. 4, a predetermined amount of the slurry-like molding material A is injected into the cavity 7.

[0013] Thereafter, as shown in FIG.
2 and the pressurizing punch 9 is lowered to remove the liquid and deposit the mixed fibers to form the fiber molded body 1.

During the deposition of the mixed fibers, the densities of the short fibers 2 are hindered by the needle-shaped portions 5 of the irregular fibers 3 and the sediment is kept at a low density. Many drainage passages can be formed in between, thereby shortening the liquid removal time and improving the productivity of the fiber molded body 1.

Specific examples of molding conditions of the fiber molded body 1 are as follows.

Dimensions of fiber molded body: diameter 86 mm, length 25
mm; slurry-like molding material: water 1000 cc, mixed fiber 68
g, blended amount of irregular fiber: 7% by volume;
30 kg / cm ² ; suction pressure of suction pump: 100 Torr. The blending amount (volume%) of the modified fiber 3 is represented by (V ₂ / V ₂ ) where V ₁ is the volume of the mixed fiber (sum of the volumes of the short fiber 2 and the modified fiber 3) and V ₂ is the volume of the modified fiber 3. V ₁ ) × 100.

The needle-shaped portion 5 of the deformed fiber 3 may be broken during handling or the like. However, if at least two needle-shaped portions 5 are provided, there is an effect of shortening the liquid removing time. The effect is improved as the number of the needle-shaped portions 5 increases.

FIG. 6 shows the relationship between the amount of the modified fiber 3 and the liquid removal time. As the liquid, 1000
cc of water was used.

It is apparent from FIG. 6 that the liquid removal time can be shortened by blending the modified fiber 3 in an amount of 0.3% by volume or more. A preferable blending amount of the modified fiber 3 for obtaining the time shortening effect is 0.5% by volume or more. However, since the abrasion resistance of the deformed fiber 3 is originally lower than that of the short fiber 2, when the blending amount of the deformed fiber 3 exceeds 55% by volume,
There is a possibility that the wear resistance of the composite member is impaired. In this respect, the amount of the modified fiber 3 is preferably equal to or less than 55% by volume.

FIG. 7 shows the relationship between the amount of the modified fiber 3 and the minimum volume fraction Vf that can be molded in the fiber molded article 1. As is clear from FIG.
When the volume is 3% by volume or more, the minimum volume fraction Vf decreases, and therefore, it is possible to obtain a thick and low-density fiber molded body 1.

[0021]

According to the present invention, by using, as the slurry-like molding material, a mixture containing short fibers and irregular fibers, it is possible to shorten the liquid removal time and improve the productivity of the fiber molding. be able to.

[Brief description of the drawings]

FIG. 1 is a perspective view of a fiber molded body.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a perspective view of a modified fiber.

FIG. 4 is an explanatory view showing a state in which a slurry-like molding material is injected into a molding die.

FIG. 5 is an explanatory view during the formation of a fiber molded body.

FIG. 6 is a graph showing the relationship between the amount of modified fibers and the liquid removal time.

FIG. 7 is a graph showing the relationship between the amount of modified fibers and the minimum volume fraction of a fiber molded article that can be molded.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fiber molded body 2 Short fiber 3 Irregular fiber 4 Core part 5 Needle-like part 6 Mold A Slurry-like molding material

Continuation of front page (56) References JP-A-2-138426 (JP, A) JP-A-1-2422734 (JP, A) JP-A-1-242735 (JP, A) JP-A-2-61014 (JP) , A) Japanese Patent Publication No. 3-68090 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 1/09 D04H 1/00-18/00

Claims (1)

(57) [Claims] 1. A slurry-like molding in which a mixed fiber comprising a short fiber (2) and a modified fiber (3) having a plurality of needle-like parts (5) extending from a core part (4) is dispersed in a liquid. Material (A)
Is injected into a molding die (6), and then the liquid is removed and the mixed fibers are deposited, thereby molding a fiber molded body for a fiber-reinforced composite member.