JPH0428772B2 - - Google Patents

Description

Detailed Description of the Invention A. Purpose of the Invention (1) Industrial Field of Application The present invention relates to a method for molding a reinforcing cylindrical fiber molded article, and in particular, to a method for molding a reinforcing cylindrical fiber molded article, in particular, a method for molding a reinforcing cylindrical fiber molded article, and particularly a method for molding a reinforcing cylindrical fiber molded article. The present invention relates to an improvement in a method for molding a reinforcing cylindrical fiber molded article by erecting an air-permeable cylindrical mold and applying suction into the mold to cause the molding material to adhere to the outer peripheral surface of the mold.

(2) Prior Art Conventionally, as a method for molding the fiber molded article, a method disclosed in JP-A-61-126357 is known.

(3) Problems to be solved by the invention In this type of molding method, the weight of the fiber molded article, and therefore the amount of fibers attached to the outer peripheral surface of the mold, is controlled by the suction action time applied to the mold. However, since the control method is indirect, strict control cannot be carried out, and as a result, there is a problem in that the weight of each fiber molded body varies widely during mass production.

In view of the above, an object of the present invention is to provide the above-mentioned molding method, which can directly control the amount of fibers attached to the mold and obtain fiber molded articles with less variation in weight during mass production.

B. Structure of the Invention (1) Means for Solving the Problems The present invention provides for an air-permeable cylindrical mold to be installed upright in a tank containing an aqueous solution of a molding material containing reinforcing fibers, and When applying a suction action to adhere the molding material to the outer peripheral surface of the mold and molding a reinforcing cylindrical fiber molded article, the concentration of the reinforcing fibers in the aqueous solution of the molding material is maintained constant. At the same time, the reinforcing fibers are uniformly dispersed, the amount of filtrated water sucked through the mold is measured, and the amount of fibers attached to the outer peripheral surface of the mold is determined from the amount of filtrated water.

(2) Effect As mentioned above, when the concentration of reinforcing fibers in the molding material is kept constant and the reinforcing fibers are still uniformly dispersed, when a suction action is applied to the inside of the mold, the material passes through the mold. An amount of reinforcing fibers corresponding to the filtrate adheres to the outer peripheral surface of the mold. Therefore, by measuring the amount of filtrate water, it is possible to directly control the amount of attached fibers and reduce the variation in weight of each fiber molded product during mass production.

(3) Example Figure 1 shows a reinforcing cylindrical fiber molded body 1 obtained through a molding process, a drying process, a firing process, etc. which will be described later. Mixed short fibers of fibers and alumina fibers are used as inorganic binders such as silica sol, alumina sol,
Or they are partially bound together by a mixed sol, and have countless voids into which the matrix can penetrate.

This fiber molded body 1 is used, for example, in order to obtain a fiber-reinforced composite cylinder sleeve by combining it with an aluminum alloy matrix when casting an aluminum alloy cylinder block. In this case, the carbon fibers mainly contribute to improving the sliding characteristics of the inner circumferential surface of the cylinder sleeve due to their lubricating ability, and the alumina fibers mainly contribute to improving the strength around the cylinder bore.

The fiber molded body 1 is obtained through the manufacturing process shown in FIG.

In Figure 2a, the mold 2 is made of shell sand (grain size
It is formed into a breathable cylindrical shape using AFS35), and has the property of completely collapsing when heated to 330-480°C.

First, the entire outer peripheral surface of the mold 2 is covered with a thin film material having a thickness of 0.10 mm and made of, for example, 6-nylon, which has air permeability and is completely burned out at the collapse temperature of the mold 2.
Cover with stockinette knitted elastic thin fabric F.

As shown in FIG. 2b, holders 3 ₁ and 3 ₂ are attached to the openings at both ends of the mold 2 by bonding, bolting, etc., and the openings are sealed.

As shown in Fig. 2c, a mold 2 is set upright in a cylindrical tank 5 of a molding device 4 containing an aqueous solution L of a molding material containing mixed short fibers of carbon fibers and alumina fibers, alumina sol, etc. , applying suction to the forming mold 2 through the opening 7 of the holder 3 ₂ ,
The molding material is applied to the outer circumferential surface of the mold 2 via the thin cloth F to a predetermined thickness to form the fiber molded body 1.

As shown in FIG. 2d, the mold 2 is placed in a pressure container 8 of a rubber press, and pressurized air is supplied from an air pressure source 9 into the pressure container 8 to form a fiber formed body 1 through the rubber 10. The outer peripheral surface of the mold 2 is pressed with a pressure of 10 kg/cm ² to adjust the shape of the fiber molded body 1 and at the same time determine the fiber volume fraction.

In this case, the diameter of the mold 2 is slightly reduced by the pressing force, but since the thin fabric F follows the shrinking action due to its shrinking action, wrinkles do not occur in the thin fabric F. Roughening of the inner circumferential surface of the fiber molded body 1 due to transfer of wrinkles can be prevented. After the pressing force is released, the mold 2 is restored to its original state, but since the thin fabric F is stretched at this time, no problem occurs.

As shown in FIG. 2e, both holders 3 ₁ and 3 ₂ are removed from the mold 2.

As shown in FIG. 2f, the mold 2 is placed in a drying oven 11 kept in an air atmosphere,
A drying process is performed for 60 minutes at an oven temperature of 120°C to evaporate and remove moisture. During this heating and drying process, the thin cloth F starts to be incinerated. Furthermore, the mold 2 expands, but the amount of expansion is absorbed by the void created by partially burning off the thin fabric F and the buffering effect of the remaining thin fabric F. No cracks will occur due to the expansion of item 2.

As shown in Figure 2g, the mold 2 is placed in a firing furnace 12 maintained in an air atmosphere, and the mold 2 is subjected to a collapse treatment for 30 minutes at an internal temperature of 450°C, and the temperature rise process completely burn out the thin cloth F. This collapse treatment causes mold 2 to collapse 100%.

The mold 2 expands before collapsing, but the amount of expansion is due to the void created as the thin fabric is burned away.
Therefore, cracks do not occur in the fiber molded product 1 as described above.

In addition, since the fibrous shaped body 1 is in contact with the mold 2 through the thin cloth F, the shell sand that is the constituent material of the mold 2 does not adhere to and remain on the fibrous molded body 1 after the mold 2 collapses. As a result, the inner circumferential surface of the fiber molded body 1 becomes smooth.

As shown in Fig. 2h, only the fiber molded body 1 was placed in the firing furnace 12 maintained in an argon atmosphere, and the fiber molded body 1 was subjected to a firing treatment for 30 minutes at a furnace temperature of 800°C. Then, the mixed short fibers are partially bonded using alumina sol. In this case, since the firing treatment is performed in an argon atmosphere, oxidation of the carbon fibers is avoided and their weight loss is prevented. Note that other inert gases may be used instead of argon.

Next, the molding device 4 will be explained in detail with reference to FIGS. 3 to 6.

FIG. 3 shows the entire molding apparatus 4, in which a tank 5 is rotatably supported on a base 13, and a flexible Suction tank 1 via connecting pipe 15
6 is connected. The suction tank 16 is arranged on a load cell 17 that measures the amount of filtered water. The upper part of the suction tank 16 is connected to a suction system piping 20 that includes a vacuum tank 18 and a vacuum pump 19, and the lower part is connected to a drainage system piping 23 that includes a water pump 21 and a water storage tank 22.

The lower end of the hollow rod 14 is connected to a piston of a rodless cylinder 24 suspended from the base 13, thereby allowing the hollow rod 14 to be raised and lowered.

In FIGS. 4 to 6, a tank 5 containing an aqueous solution L of a molding material has an open top surface and a hollow shaft portion 25 on the outer surface of the bottom.
is supported in a hole 27 formed in the base 13 via a plurality of bearings 26 . The air passing rod 14 is the mold 2
It is provided with a mounting flange 28 at the upper end so as to be installed upright in the tank 5, and is inserted into the hollow shaft portion 25 via a plurality of seal members 29 so as to be movable up and down.

A pulley 30 ₁ is fitted into the hollow shaft portion 25 , and the pulley 30 ₁ and the motor 3 supported by the base 13
A transmission belt 32 is stretched between the pulley 30 ₂ and the pulley 30 2 shown in FIG. 1 (FIG. 3). The mold 2 is removably installed on the mounting flange 28 with the opening 7 of the holder 3 ₂ aligned with the through hole 14 a of the hollow rod 14 . The tank 5 is disposed immovably on the mold 2 and is configured to be rotatable around the axis of the mold 2.

On the outer periphery of the mold 2, a plurality of rectifying plates 33 extending in the axial direction and radial direction of the mold 2 are arranged at equal intervals in the circumferential direction. The upper end of each rectifying plate 33 is fixed to the annular ceiling surface of a cover 35 covering the tank 5 via an annular mounting plate 34, and the lower end of each rectifying plate 33 is arranged near the bottom of the tank 5. The cover 35 is fixed to the upper surface of the base 13 with a plurality of bolts 40, and therefore each rectifying plate 33 is immovably disposed around the outer periphery of the forming mold 2.

A plurality of first stirring plates 36 ₁ are provided on the inner peripheral surface of the tank 5.
The first stirring plates 36 ₁ are arranged at equal intervals in the generatrix direction of the inner circumferential surface of the tank 5, and are also arranged at equal intervals in the circumferential direction of the inner circumferential surface. The tank 5 rotates clockwise as shown by the arrow in FIG. 5, and each first stirring plate ₃₆₁ is
It is inclined so that its lower edge is located on the front side in the tank rotational direction, and its upper edge is located on the rear side in the tank rotational direction.

A plurality of second stirring plates 36 ₂ whose inclinations are opposite to each of the first general plates 36 ₁ are attached to each current plate 33 so as to overlap with the rotation locus of each first stirring plate 36 ₁ . That is, for each straightening plate 33, the second stirring plates 36 ₂ at the uppermost and intermediate positions are positioned between the uppermost and intermediate positions and between the first stirring plates 36 ₁ at the intermediate and lowest positions, respectively, during tank rotation. and the lowest second stirring plate 36 ₂
is located near the bottom of the tank 5 and below the lowest first stirring plate ₃₆₁ .

When forming the fiber molded product 1, the tank 5
5 clockwise, and vacuum pump 1.
9 and the water pump 21 are operated to apply suction into the mold 2.

As a result, the growth material is stirred near the inner peripheral surface of the tank 5 due to the inclination of each of the first and second general plates 36 ₁ and 36 ₂ , and this stirring action disturbs the flow of the molding material. Since the molding material is in a flowing state, it is possible to prevent the molding material from stagnation at the bottom of the tank 5 and to sufficiently stir the molding material, thereby making it possible to uniformly disperse the mixed short fibers.

When the flow of molding material collides with each rectifying plate 33,
The flow velocity is weakened and a suction action is applied within the mold 2, so that the flow becomes a laminar flow toward the outer circumferential surface of the mold 2 as shown by the arrow in FIG. This improves the adhesion of the molding material to the mold 2, and the adhered molding material
It is almost never removed by the current.

In the above-mentioned molding operation, when the concentration of the mixed short fibers in the molding material is kept constant and the mixed fibers are uniformly dispersed, suction is applied to the inside of the mold 2, and the filter passing through the mold 2 is The amount of mixed short fibers depending on the liquid adheres to the outer peripheral surface of the mold 2. Therefore, by measuring the amount of filtered water with the load cell 17, the amount of attached fibers can be directly controlled.
It is possible to reduce variations in weight of each fiber molded body 1 during weight calculation.

After the molding operation, the cover 35 is removed and the mold 2 is moved into the tank 5 using the rodless cylinder 24.
Then, the mold 2 is raised above the hollow rod 14.
It is more important to remove it.

Next, an example of the fiber molded body 1 will be explained.

(a) Preparation of aqueous solution L of molding material As reinforcing fibers, 0.005 to 0.1% by weight of carbon fibers with an average diameter of 6 to 8 μm and an average length of 0.8 mm and 0.22% of alumina fibers with an average diameter of 3 to 4 μm and an average length of 100 to 200 μm are used. ~0.8% by weight, 4-6% by weight of silica sol or alumina sol as inorganic binder, and 0.2% by weight of antifoaming agent and surfactant.
% by weight and 93.4-95.4% by weight water (32). The calculated fiber concentration in the tank 5 of the molding material obtained in this way is 5.6
g/Kg.

(b) Dimensions of mold 2 The upper outer diameter is 78 mm, the lower outer diameter is 74 mm, and the thickness is 5 mm.

Using the aqueous solution L of the molding material and the mold 2, a molding operation is performed with the apparatus 4 under the conditions of a tank rotation speed of 40 rpm and a degree of vacuum of -63 cmHg, with the aim of obtaining a fiber molded article 1 having a weight of 56 g. .

From the relationship between the amount of fibers attached to the outer peripheral surface of the mold 2 and the amount of filtration that has passed through the mold 2, and therefore the amount of filtrate water, it is necessary to filtrate in order to mold the fiber molded body 1 having a weight of 56 g as described above. water amount
It is necessary to set it to 6800g.

In this case, since the amount of water present from the tank 5 to the suction tank 16 is 3200 g, it is sufficient to measure 10000 g (6800 g + 3200 g) of the filtrate using the load cell 17.

Figure 7 shows 100 fiber molded bodies 1 based on the above.
A histogram is shown when the weights of the fiber molded bodies 1 were determined.

As is clear from FIG. 7, according to the present invention, 56
It is possible to obtain a fiber molded article 1 with a small variation in weight of ±2 g.

For comparison, 100 fiber molded bodies were similarly molded using the molding device 4, measuring the suction action time for 2 minutes, and their weights were found to be 56±.
It has been found that there is a large variation in weight, as shown in 3.5g.

C. Effects of the Invention According to the present invention, the concentration of reinforcing fibers in the molding material is kept constant, and the suction action is applied inside the mold while the reinforcing fibers are uniformly dispersed.
The amount of reinforcing fibers corresponding to the filtrate passing through the mold can be attached to the outer circumferential surface of the molded body, and by measuring the amount of filtrate water, it is possible to directly determine the amount of fibers attached to the outer circumferential surface of the mold. By controlling this, it is possible to reduce the variation in weight of each fiber molded product during mass production.

[Brief explanation of drawings]

Figure 1 is a perspective view of the fiber molded body, Figure 2 is a manufacturing process diagram of the fiber molded body, Figure 3 is a front view of an embodiment of the molding device, and Figure 4 is a longitudinal sectional view of the main parts of the molding device. ,
Fig. 5 is a sectional view taken along the line shown in Fig. 4, Fig. 6 is a perspective view showing the relationship between the first and second stirring plates and rectifying plates, and Fig. 7 is a histogram showing the relationship between the weight and number of fiber molded bodies. be. L...Aqueous solution of molding material, 1...Fiber molded body,
2... Molding mold, 5... Tank, 6... Suction tank, 17... Load cell, 18... Vacuum tank,
19...Vacuum pump, 21...Water pump.

Claims (1)

[Claims] 1. A breathable cylindrical mold is set upright in a tank containing an aqueous solution of a molding material containing reinforcing fibers, and the molding material is attached to the outer peripheral surface of the mold by applying suction to the mold. When molding a reinforcing cylindrical fiber molded article, the concentration of reinforcing fibers in the aqueous solution of the molding material is kept constant, and the reinforcing fibers are uniformly dispersed and sucked through the mold. A method for molding a reinforcing cylindrical fiber molded body, comprising measuring the amount of filtrated water and determining the amount of fibers attached to the outer peripheral surface of the mold from the amount of filtrated water.