JPH02232325A - Production of short fiber formed body - Google Patents

Abstract

PURPOSE:To easily produce a short-fiber formed body of complicated shape by swelling a shielding member to be allowed to adhere by suction to the master pattern plate by means of uniform humidification and uniformly providing flexibility and extensibility. CONSTITUTION:A shielding member 9 (water-soluble polyvinyl alcohol film) is uniformly humidified by means of water or solvent and swollen, which is sucked by the surface of a master pattern plate 1 and is allowed to adhere to a master pattern 4 by suction. A coated layer 17 is formed on the surface of the above shielding member 9, and then, a hollow part formed by placing a molding flask body 18 on the master pattern plate 1 is filled with a filler 19, and vibrations are applied to the above to increase filling density. Subsequently a sheet 25 is placed on the above molding flask body 18 and sucked from a decompression chamber 20 side, and a half mold is formed from the filler 19 and the master pattern plate 1 is separated. Then, two half molds are joined together, and a short fiber-dispersed solution 26 is poured into the resulting cavity 31 and sucked from the coated layer 17 side and the filler 19 side, by which a short fiber formed body 32 is formed in the cavity 31. The solidified formed body 32 is taken out together with the shielding member 9, the water-adsorbed coated layer 17, and a water-condensed layer 33 in the filler 19 and dried, by which a short fiber-reinforced formed body can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a molded body made of short fibers used in producing metal composite materials.

(Prior art and its problems) Conventionally, when casting light metal products such as aluminum, in order to improve the material quality of the light metal product, a reinforcing molded body made of inorganic short fibers was set in a mold and The method used is to cast molten metal to form a composite.

On the other hand, as a method for obtaining the above-mentioned reinforcing short fiber molded product, water, a dispersant, and in some cases a binder are added to reinforcing short fibers or whiskers (hereinafter simply referred to as reinforcing short fibers), and the mixture is sufficiently stirred to form short reinforcing fibers. A method of preparing a dispersion liquid, filtering the short fiber dispersion liquid to make a molding material, compression molding this molding material with a mold etc., and drying the obtained molded body,
A method is known in which a short fiber dispersion obtained in the same manner as described above is suction molded through a suction molding port and the resulting molded product is dried.

However, these methods have the following problems. That is, in the case of filtration and compression molding, it takes time to filter the short fiber dispersion, and it is difficult to obtain a molded article with a complicated shape by compression molding using a mold. Furthermore, in the case of molding using a suction mold, the short fiber dispersion liquid is sucked through the suction port of the suction mold, so there is a drawback that the shape of the molded product is limited by the shape of the suction port.

(Objective of the Invention) The present invention was made in view of the above-mentioned problems, and it is an object of the present invention to provide a method for easily producing a short fiber molded article having a complicated shape.

(Means for Solving the Problems) In order to achieve the above object, the present invention uniformly humidifies and swells a shielding member permeable to a solvent of a short fiber or whisker dispersion solution with water or a solvent, The shielding member is brought into close contact with the surface of the original model board by suction, a modeling frame is placed on the original model board, and a filler made of granular material such as inorganic aggregate is filled into the modeling frame. The upper surface of the material is sealed and the modeling frame is subjected to negative pressure, thereby solidifying the filling material in a vacuum and adsorbing the shielding member to the filling material side.Then, the original model board is released from the shielding member and halved. A mold is molded, the half mold is matched with another half mold molded in the same manner to form a cavity, and the short fiber dispersion solution →H→ immediately after stirring is injected into the cavity. It is characterized in that the negative pressure state of the half-split type is released afterward.

Progress of the invention The inventors had previously applied for a patent in JP-A-62-268608 as a method for forming a complex-shaped sintering prototype, and this method was applied for the production of short fiber compacts. As a result of conducting various tests, we found the following problems. That is, in the step of closely adhering the shielding member to the original member, heat softening treatment is performed using a burner or the like in order to increase the flexibility of the shielding member. For this reason, for example, when a polyvinyl alcohol film is used, dehydration reaction and deterioration occur due to heating, and polyvinyl ether is generated, resulting in a portion that becomes insoluble in the solvent, and when a short fiber dispersion solution is injected, the solvent is absorbed and removed from the shielding member. becomes uneven and becomes fleshy. Non-uniformity may occur, solvent penetration may be poor, and local defects may occur. In addition, the partial deterioration of the shielding member may cause concentrated stress, which may partially break the shielding member and cause the short fiber dispersion solution to flow out.

Here, the inventors have come to consider humidifying and swelling the shielding member as a method of uniformly imparting flexibility and extensibility to the shielding member and adhering it to the original member without using heating.

A detailed explanation will be given below based on experimental examples and examples.

Experimental Example 1> An experiment was conducted on swelling properties by changing the solvent and the type of shielding member. In order to do this, a sample of the shielding member was placed in a beaker filled with each solvent and its solubility was investigated.The results are shown in the table below.

As described above, swelling was possible by combining an appropriate solvent and a shielding member. The surface dissolved in this experiment was also considered to swell.

<Experimental example 2> In order to investigate a uniform humidification method, a water-soluble polyvinyl alcohol film was used as a shielding member, water was used as a solvent, and methods of immersion in the solvent, spray method, and immersion in solvent-containing powder were investigated. did.

In the solvent immersion method, the film is immersed in water in a beaker for about 3 minutes. The spray method uses an ultrasonic humidifier from the spray port.
The film is treated with a water droplet at the 0 cm position. In the immersion method, the film is immersed for 3 minutes in a porous humidifying material prepared by uniformly adding 3 to 5% of water to a porous material (AL13PC manufactured by Showa Denko ■, particle size: 80 μm).

As a result, it was found that the dipping method and spraying method resulted in films that were easily torn and lacked flexibility and extensibility.

In the case of the embedding method, the film was humidified uniformly, and the film also exhibited good flexibility and extensibility.

Example Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 shows an original model plate (1), which includes a base (3) having a hollow chamber (2) inside.
A master model (4) is attached to the upper part of the base (3) and the master model (4), and a plurality of ventilation holes (6) communicating with the hollow chamber (2) are bored in the base (3) and the master model (4). (2) is connected to a suction device (not shown) via a hose (7) and a switching valve (8). Next, FIG. 2 shows a shielding member (9
) is shown undergoing humidification and swelling treatment.

That is, in a saucer-shaped container (IO), water was uniformly poured into a porous material (AL13PC manufactured by Showa Denko ■, particle size 80μ) for 3 to 5 minutes.
Approximately 2 c of the porous additive material (11) added by weight%
Then, a shielding member (9) made of a water-soluble polyvinyl alcohol film with a thickness of 30μ is adsorbed and held on the film holding frame (l2), and placed on the porous humidifying material (11). Place it. Note that the film holding frame (
12) has a hollow chamber (work 3) inside the wall, and a suction hole (14) communicating with the hollow chamber (13) is bored in the bottom slope, and the hollow chamber (13) is connected to a hose (15). ) and a switching valve (I6) to a suction device (not shown). Such a holding frame (12) has a hollow chamber (l3
) and a suction device (not shown) are communicated with each other to connect the holding frame (l2).
The shielding member (
9) Hold the shielding member (9) by suction by pressing it against the top surface,
It is placed on the porous humidifying material (1).

Next, the porous humidifying material (
The same material as 11) was spread evenly in a layer of about 1 cm to form the state shown in Figure 2. The shielding member (9) is left still in this state for about 3 minutes to uniformly humidify the shielding member (9). After that, the porous humidifying material (l1) on the shielding member (9) is removed, and the film holding frame (
Shielding member (9) swollen by raising l2)
was gotten.

Next, the hollow chamber (2) of the original model plate (1) is communicated with a suction device (not shown), and while a suction action is exerted on the surface of the original model plate (1), the swollen shielding member (9) is moved to the holding frame. (l2) and placed on the surface of the original model plate (1). As a result, the shielding member (9) is extended by the suction action from the original model plate (1) and is brought into close contact with the original model (4) by suction. Thereafter, the suction action of the holding frame (12) is cut off, and the holding frame (l2) is removed from the original model board (1), and a coating layer (17) is placed on the upper surface of the shielding member (9).
form.

The coating mold layer (17) was mainly composed of diatomaceous earth of several microns, which is a porous aggregate, and was formed by applying a coating agent made by adding graphite and ethyl alcohol as a solvent to this.

Next, a modeling frame (18) is placed on top of the original model board (1), and particles such as inorganic aggregate are placed in the hollow space defined by the modeling frame (18) and the original barrel board (1). Filling material made of material (19)
The filling material (19
) to increase the packing density.

The modeling frame (18) has an annular decompression chamber (20) in the main body.
), and the decompression chamber (20) is connected to a hose (21).
and is communicatively connected to a suction device (not shown) via a switching valve (22).

In addition, a large number of ventilation holes (23) communicating with the decompression chamber (2o) are bored in the inner wall of the main body, and the inner wall surface of the main body has holes for preventing the filling material (19) from passing through. A filter (24) with narrowness is installed.

In this state, the decompression chamber (2o) and a suction device (not shown) are communicated with each other, and a non-ventilated sheet (25) is placed on the upper surface of the modeling frame (18), resulting in the state shown in FIG. Through this operation, the filling material (19) receives external pressure via the sheet (25) due to the suction action from the decompression chamber (2o) side of the modeling frame (18), and is brought into a vacuum assimilation state. In this state, communication between the hollow chamber (2) of the original model board (1) and the suction device (not shown) is cut off, and when the modeling frame (18) is separated from the original model board (1), the coating layer (l7) is removed. Formed shielding member (9)
is adsorbed to the filler (19) side, and then the mold is cut out to obtain a half-split mold for injecting the short fiber dispersion solution.

By the same operation as above, another half-split mold is molded, the two half-split molds are matched, and the short fiber dispersion solution (26
The injection tube (28) communicating with the bottom of the storage tank (27) in ) is communicated with the short fiber dispersion solution inlet (29) to bring it into the state shown in FIG.

In the examples, the short fiber dispersion solution (26) uses potassium titanate whiskers (manufactured by Otsuka Chemical Co., Ltd., manufactured by Kiki, chemical composition K, 0.5 T i O. true specific gravity 3.3) as the short fibers. 500 parts by weight of water and a dispersant (polymer polycarboxylic acid ammonium salt) were added to 100 parts by weight of short fibers and stirred using an ultrasonic cleaner until immediately before injection.

In this state, the gate (30) is opened and the short fiber dispersion solution (2
6) is injected into the cavity (31).

The water in the short fiber dispersion solution (26) injected in this way permeates the shielding member (9) and is further sucked into the coating layer (17) and filler (19), and as a result, the water in the short fiber dispersion solution (26) is absorbed into the cavity (3).
1) A molded body (32) made of short fibers is formed inside.

The molded article (32) made of short fibers is kept in this state for a predetermined period of time to solidify it to a state where it can maintain its shape even if it is demolded.

Next, communication between the vacuum chambers (20) of the vertically aligned modeling frames (18) (18) and a suction device (not shown) is cut off, and the vacuum state inside the modeling frames (18) is released, and the upper sheet ( 25), remove the upper modeling frame (18).
remove. This operation collapses the filler (19) that constituted the upper half mold.

Next, the solidified short fiber molded body (32) and the shielding member (
9) as well as a coating layer (17) that adsorbs water and a filler (1).
The moisture condensation layer (33) of 9) is taken out in one piece.
It will be in the state shown in the figure. This was dried at a temperature of 60 to 70°C for 8 hours, and then at 100°C for 24 hours. At this time, the coating layer (I7) and the moisture condensation layer (33) are dried, separated from the surface of the short fiber molded article (32), and collapsed to obtain a short fiber reinforced molded article having a predetermined shape.

In the examples, potassium titanate whiskers were used as short fibers, but other materials such as alumina, silicon carbide, silicon nitride,
Any material may be used as long as it is a reinforcing short fiber such as carbon or whisker.

Further, in the examples, a short fiber binder was not used, but an organic binder such as a phenol resin or polyvinyl alcohol, or an inorganic binder such as water glass may be dispersed in the solution together with the short fibers.

Furthermore, although a polyvinyl alcohol composition was used as a water-soluble shielding member in the examples, other materials such as polyethylene glycol, polyethylene oxide, methyl cellulose, carboxymethyl lose, sodium polyacrylate, polyvinyl pyrrolidone, and polyvinyl butyral were also used. A composition comprising the following may be used.

Next, the reinforced molded body formed as described above was set in a mold and preheated to 800°C, and then 730'C molten aluminum was poured and heated to 500°C under a pressure of 1000 kg/am'. A whisker-reinforced aluminum composite was obtained by holding for a minute.

(Effects of the Invention) As is clear from the above explanation, since the method of uniformly humidifying and swelling the shielding member adsorbed to the original model board with water or a solvent is used, flexibility and malleability are uniformly imparted. ,
Complex shapes can be molded easily and without any problems, and since water in the short fiber dispersion solution is suctioned and removed from the entire surface of the cavity, the molding time can be significantly shortened, and various other effects are achieved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the original model plate, Fig. 2 is a sectional view showing the humidified state of the shielding member, Fig. 3 is a sectional view showing the forming state of the half-split mold, and Fig. 4 is the forming state of the molded body. 5th cross-sectional view showing
The figure is a sectional view showing a state in which the molded body is taken out. (l): Original model plate (9): Shielding member (18): Molding frame (19): Filler (26): Short fiber dispersion solution (31): Cavity 3 Figure

Claims (1)

[Claims] A shielding member (9) permeable to the solvent of the short fiber or whisker dispersion solution (26) is uniformly moistened with water or a solvent to swell it, and the swollen shielding member (9) is attached to the original model plate (1
), place the modeling frame (18) on the original model plate (1), and place the filler (19) made of granular material such as inorganic aggregate in the modeling frame (18). ), and the upper surface of the filler (19) is sealed to create a negative pressure inside the modeling frame (18), thereby solidifying the filler (19) in a vacuum and at the same time closing the shielding member (9) with the filler. Then, the original model plate (1) is released from the shielding member (9) to form a half mold, and the half mold is matched with another half mold molded in the same manner. to form a cavity (31), inject the short fiber dispersion solution (26) immediately after stirring into the cavity (31), and then release the negative pressure state of the half-split mold. A method for producing a short fiber molded article.