JPH0448326B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to a method for manufacturing hollow molded articles from ceramic slurry. (Prior Art) In general, as shown in FIG. 4, a slurry pressure casting device used for manufacturing the above-mentioned hollow molded product includes a plaster mold 2 for casting which is erected by a support member 1, and a slurry for molding. The slurry in the supply container 4 is pressurized and supplied into the plaster mold 2 for casting. In such a casting device, water in the slurry supplied into the plaster mold 2 is gradually absorbed into the plaster mold 2, and when the deposited thickness reaches a predetermined thickness, the plaster mold is Unattached slurry is discharged from inside 2. The inked hollow molded product is then naturally dried in the plaster mold 2, and then released from the mold and subjected to drying, appropriate heat treatment, firing, etc. (Problem to be Solved by the Invention) Incidentally, in this manufacturing method, it is important to make the wall thickness of the hollow molded product a predetermined thickness, but in the past, slurry was constantly supplied from the supply container to the plaster mold. The wall thickness is adjusted by adjusting the casting time. However, when such measures are taken, due to differences in the mixing lot of slurry or variations in the water absorption and adsorption capacity of the plaster mold, etc.
Differences in wall thickness often occur between molded products, and it takes a long time to dry the molded products in the plaster mold. Therefore, the purpose of the present invention is to suppress the difference in wall thickness between molded products as much as possible by adjusting the wall thickness of the hollow molded product based on the volume of water actually absorbed by the plaster mold from the slurry. In addition, it is intended to shorten the time required for manufacturing by forcibly drying the molded product within the plaster mold. (Means for Solving the Problems) The present invention provides a method for manufacturing a hollow molded product in which a slurry is supplied into a plaster mold for casting to form a hollow molded product. The slurry is supplied according to the decrease in water content in the slurry, and when the supply amount of slurry reaches a predetermined volume, the supply is stopped and the unattached slurry in the plaster mold is discharged. This method is characterized in that hot air is supplied into the mold to dry the hollow molded product adhering to the mold, and then taken out from the mold. (Operations and Effects of the Invention) In this manufacturing method, the moisture of a predetermined volume of slurry filled in a plaster mold is absorbed by the plaster mold and gradually becomes ink, reducing the volume (moisture) in the plaster mold.
is gradually decreased, and a volume of slurry corresponding to this decrease is supplied, and an amount of slurry corresponding to this supply volume is deposited on the plaster mold.
Therefore, if the supply of slurry to the plaster mold is stopped when the supply amount of slurry reaches a predetermined capacity, and the unattached slurry is promptly discharged from the plaster mold, the thickness of the deposit inside the plaster mold can be reduced. is always approximately constant, and there is almost no difference in the wall thickness of the resulting molded product. In addition, since warm air is supplied into the plaster mold after discharging the unattached slurry, the molded product inside the plaster mold is forcibly dried, which shortens the drying time, which in turn leads to hollow molding. The time required to manufacture products can be shortened. (Embodiments) (1) Casting Apparatus A casting apparatus suitably employed in the manufacturing method of the present invention is shown in FIG. The casting device includes a supply tank 11, a cylinder 12, a plaster mold 13, and a support mechanism 1.
4 and a hot air generator 15, the supply tank 1
1, the cylinder 12 and the plaster mold 13 are connected to the first conduit 2
The plaster mold 13 and the hot air generator 15 are connected by a third conduit 23. The supply tank 11 is a known supply container that accommodates a large volume of slurry, and is equipped with an agitator 11a that uniformly stirs the contained slurry. Such supply tank 1
1, a first conduit 21 is connected to the center of its bottom via a connecting pipe 11b. cylinder 1
Reference numeral 2 designates a second supply container containing a small volume of slurry, which is made of transparent plastic and has a volume scale.As shown in FIG. , 12c in the vertical direction. In this cylinder 12, the first conduit 21 and the second conduit are connected via a connecting pipe 12d provided on the lower flange 12c.
They are connected by a conduit 22. connecting pipe 11b,
12d has first and second on-off valves 24a and 24b.
is interposed. In addition, in such a cylinder 12, the connecting pipe 1 provided on the upper flange 12b
It is connected to the fourth conduit 25 via 2e. This fourth conduit 25 is a connecting pipe 1 provided on the lid 11c of the supply tank 11 and connected to the compressor.
1d. Each connecting pipe 11d, 12e
are interposed with third and fourth on-off valves 24c and 24d, and fifth and sixth on-off valves 24e and 24f. The plaster mold 13 is a pair of vertically divided molds 13a, 1.
3b is integrated with a plurality of clamps 13c shown in FIG. 3 in the shape of a rectangular tube, and the central portion of its cross section is provided with a circular inner hole 13d that penetrates in the vertical direction.
Therefore, the plaster mold 13 can be divided into two molds 13a and 13b by removing the clamp 13c. In such a plaster mold 13, the lower base 14a of the support mechanism 14 is
A viewing plate 16a made of transparent plastic and a sealing plate 16b made of rubber are interposed between the upper surface of the plaster mold 13 and the pressing plate 14b. A connecting pipe 14c is provided on the lower surface of the lower stand 14a, and this connecting pipe 14c is provided with seventh, eighth, and ninth on-off valves 24g, 24h, and 24i, and the plaster mold 13
It is fluid-tightly connected to the lower end of the inner hole 13d and connected to the second conduit 22 and the third conduit 23. The hot air generator 15 consists of a compressor 15a and a heating section 15b, and the air supplied by the compressor 15a is heated to 40% by the heater in the heating section 15b.
The third conduit 23 is heated to a temperature of ~60°C.
It is supplied through the inner hole 13d of the plaster mold 13. In the casting apparatus having such a structure, a ceramic slurry is contained in the supply tank 11 and stirred homogeneously prior to casting, and all the on-off valves are closed. Also, cylinder 1
2. The plaster mold 13 and the hot air generator 15 are connected as shown in FIG. Then, when the third on-off valve 24c is opened to apply compressed air to the upper surface of the slurry in the supply tank 11 to pressurize it, and the first, second, and seventh on-off valves 24a, 24b, and 24g are opened, The slurry in the supply tank 11 is forced into the inner hole 13d of the plaster mold 13 through the first and second conduits 21 and 22.
When the slurry in the inner hole 13d reaches the viewing plate 16a, the sixth opening/closing valve 24f is adjusted to introduce the slurry to a predetermined height into the cylinder 12, and then the second opening/closing valve 24b is closed and the sixth opening/closing valve 24f is adjusted to introduce the slurry to a predetermined height. 3. Open the fifth on-off valves 24d and 24e.
As a result, the pumping of the slurry into the supply tank 11 is stopped, and thereafter the slurry is pumped from the cylinder 12. When the slurry in the cylinder 12 drops to a predetermined height, that is, when a predetermined amount of slurry is forced into the inner hole 13d of the plaster mold 13 from within the cylinder 12, the seventh on-off valve 24g is immediately closed. At the same time, the pressing plate 14b is loosened, and the eighth opening/closing valve 24h is opened to discharge the unattached slurry in the inner hole 13d. After removing mud, close the eighth on-off valve 24h and open the ninth on-off valve 24i,
Hot air of 40 to 60℃ is sent from the hot air generator 15 to the third conduit 2
3 into the inner hole 13d of the plaster mold 13 for a predetermined period of time. As a result, the ceramic pipe attached in the inner hole 13d is dried and the plaster mold 1
3, it can be released from the mold and taken out. Incidentally, the relationship between the supply amount V (cc) of slurry supplied from the cylinder 12 into the inner hole 13d of the plaster mold 13 and the wall thickness t (cm) of the hollow molded product is expressed by the following equation. V=ρπ{D ₀ ² −(D ₀ −2t) ² }/4×l(W ₀ −W ₁ )/
100 However, ρ: Density of the compact (g/cm ³ ), D ₀ : Outside diameter of the compact (cm), l: Length of the compact (cm), W ₀ : Slime moisture (wt%), W ₁ : Immediately after mud removal. Molded object moisture (wt%) Therefore, if the amount of slurry in the cylinder 12 supplied into the inner hole 13d of the plaster mold 13 is controlled based on the pre-calculated value of V, the wall thickness of the obtained molded object can be increased. t
is a predetermined value, and almost no difference in wall thickness occurs between molded products. (2) Casting experiment Using ceramic slurry with a moisture content of 15 wt%, the outer diameter is 40 mm, the wall thickness is 7 mm, the length is 1500 mm, and the density is 2.6 g/cm ³ .
Immediately after mud removal, a pipe with a water content of 9 wt% was molded using the casting apparatus shown in Figure 1. The amount of slurry supplied from the cylinder into the inner hole of the plaster mold during molding was controlled at 170 c.c. In addition, the temperature of the hot air blown from the hot air generator is approximately 50℃, and the wind speed inside the inner hole of the plaster mold is 1m/
sec, and the air blowing time was about 1 hour. Table 1 shows these molding conditions and the wall thickness of the molded product. Table 2 shows the results of molding pipes similar to those described above using the casting apparatus shown in FIG. 4 and adjusting the wall thickness by adjusting the casting time as a comparative example. Regarding the quality of the wall thickness of each molded product in the table, those within the range of (7±1) mm were evaluated as good, and those outside of this range were evaluated as failed. 1st
In the examples according to the present invention shown in the table, the time required for one cycle from the start of the first production to the start of the second production is a maximum of about 2 hours, whereas in the comparative example shown in Table 2 The time required for one cycle is 5 to 6 hours.

【table】

[Table] Referring to these results, if the manufacturing method of the present invention is adopted, the thickness of all molded products will be (7 ± 1) mm.
, and can be controlled by an extremely simple means of supplying a constant volume of slurry.
When conventional manufacturing methods are used, there are large variations in wall thickness between molded products, often falling outside the range of (7 ± 1) mm, and the casting time must be adjusted each time, which is extremely troublesome. Yes, and it takes a long time to manufacture.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a casting device employed in a manufacturing method according to an embodiment of the present invention, FIG. 2 is an enlarged partial longitudinal sectional side view of a cylinder in the same device, and FIG. 3 is a gypsum casting device in the same device. An enlarged perspective view of the upper part of the mold;
FIG. 4 is a schematic diagram of a conventional casting device. Explanation of symbols, 11... Supply tank, 12... Cylinder, 13... Plaster mold, 14... Support mechanism, 1
5... Hot air generator, 21-23, 25... Conduit.

Claims (1)

[Claims] 1. In a method for manufacturing a hollow molded article in which a slurry is supplied into a plaster mold for casting to form a hollow molded article, after filling the slurry into the plaster mold, the amount of water reduced in the slurry in the mold is The slurry is supplied, and when the supply amount of the slurry reaches a predetermined volume, the supply is stopped and the unattached slurry in the plaster mold is discharged, and then hot air is supplied into the plaster mold to fill the mold. A method for manufacturing a hollow molded article, which comprises drying the adhered hollow molded article and then taking it out from within the same mold.