JPH0390302A - Manufacture of inorganic product - Google Patents

Abstract

PURPOSE:To form a molded product in a short time even it is a thick one by a method wherein slurry stock in a forming space is pressurized and heated under the condition that suction force by vacuum is applied to the forming space. CONSTITUTION:Under the condition that molds are closed, slurry stock 30 is forced from a screw type extruder 23 in a forming space, which are formed by forming recesses 3a and 13a. By sucking under vacuum through suction and compression pipes 4 and 14, which are respectively provided in a top force and in a bottom force, the water content in the slurry 30 is extracted by suction. The slurry stock 30 fed to the forming space is heated in a pipe 24, which extends from the screw type extruder 23, and, further heated by planar heat generating bodies, which are respectively built in the top and bottom forms 2 and 12, at the stage being forced in the forming space. Thus, the formation of the slurry is rapidly completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a method for producing inorganic products such as ceramics.

[Prior Art] Ceramic products are generally molded by a casting method in which raw material slurry is injected into a mold and molded. This type of casting method can be roughly divided into the following two types.

The first method uses a plaster mold as a mold, pours the raw material slurry into the plaster mold, uses the fine pore structure of the plaster mold to absorb moisture, and creates a molded body, which is then removed. This method involves molding, hardening, and then firing.

The second method is to make a mold using a porous material with water permeability such as a porous plastic material, pressurize and inject the raw material slurry into the mold, and dehydrate the molded product using the pressure. This method involves making a mold, removing it from the mold, and then firing it.

The first method described above has the disadvantage that production efficiency is extremely low because it takes time to dehydrate the water in the raw material slurry. The second method has extremely high production efficiency because pressure is applied to the raw material slurry to perform forced dehydration. Moreover, even when molding a molded product with a complicated shape, it has the advantage that molding can be performed with less molding distortion.

[Problem to be solved by the invention]

In this way, the second casting method described above is excellent in terms of molding efficiency and moldability, but when molding a thick-walled product, it is still necessary to dehydrate the water in the raw material slurry. The problem is that it takes a long time to complete. In order to solve such problems, it is possible to evacuate the inside of the mold to facilitate dehydration, or to increase the injection pressure of the raw material slurry. However, no matter which method is tried, when molding a thick-walled molded product, the raw material slurry that is in contact with the mold surface in the molding space quickly dehydrates and solidifies. Because the water in the raw material slurry cannot be smoothly dehydrated, it is not possible to shorten the molding time. As described above, conventionally it has been impossible to mold thick-walled molded products in a short time using the casting method, and there is a strong desire for improvement.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a method that allows even thick-walled molded products to be molded in a short time.

[Means for Solving the Problems] In order to achieve the above object, the method for manufacturing an inorganic product of the present invention uses an upper mold and a lower mold, at least one of which has water permeability, and is manufactured using both of the molds. A method for manufacturing an inorganic product, in which a raw material slurry is injected into a molding space and water is dehydrated using the water permeability of the mold to create a molded product, and the molded product is made into an inorganic product through a curing process. In the molding process, a vacuum suction force is applied to the molding space, and pressure and heat are applied to the raw material slurry in the molding space.

[Effect]

That is, as mentioned above, when molding a raw material slurry by the casting method, the method of the present invention applies vacuum suction force to the raw material slurry and pressurization pressure, and heats it in that state. It adds thermal energy due to Therefore, the boiling point of water in the raw material slurry is lowered under reduced pressure, making it easier to evaporate at low temperatures. As a result, in the mold of the mold, before the dehydration and solidification of the raw material slurry that is in contact with the mold surface begins, the raw material slurry on the center side is dehydrated, and the raw material slurry that is in contact with the mold surface is dehydrated. Not only this, but also the water content of the raw material slurry in the center is quickly dehydrated. Therefore, even thick molded products can be dehydrated in a short time and can be made into molded products. Furthermore, in the method of the present invention, the moisture in the raw material slurry is evaporated and dehydrated at a low temperature of less than 100°C, so that the molded product structure Ii component in the raw material slurry is not thermally denatured by heating. Therefore, it becomes possible to dehydrate thick-walled products in a short period of time without adversely affecting the molded product.

Next, examples will be described.

〔Example〕

FIG. 1 shows a casting apparatus used in the present invention.

In the figure, reference numeral 1 indicates a square plate-shaped upper base plate of the upper mold, including a square plate-shaped base plate 20 of a hydraulic cylinder 19 and four arms 21.
22, and are moved up and down by the drive of a hydraulic cylinder 19. This upper base plate l is provided with an upper formwork 2 having a U-shaped cross section facing downward, and a porous elastic body 3 made of resin with continuous pores is disposed within the U-shaped upper formwork 2. has been done. A molding recess 3 a is formed on the surface of the porous elastic body 3 .

Furthermore, a suction/compression pipe 4 having a large number of openings on the outer peripheral surface is inserted inside the porous elastic body 3, and the end thereof is connected to a vacuum pump via a vacuum suction pipe 5 and a compressed air vibro. (not shown) and a compressed air pump (not shown). Reference numerals 7 and 8 indicate switching valves for switching between the vacuum suction and compressed air. 11
is a lower base plate of the lower mold corresponding to the upper base plate l, and is supported and fixed by a support column 91O. 12 is the lower base plate 1 mentioned above
1 is a lower formwork with a U-shaped cross section, and a porous elastic body 13 made of resin and having continuous pores is disposed inside.

The surface of this porous elastic body 13 is also formed with a molding recess 13a, similar to the porous elastic body 3 of the upper mold 2, and a suction/compression pipe 14 is inserted inside. A vacuum suction vibrator 15 and a compressed air vibrator 16 are connected to the end of this suction/compression pipe 14.
They are each operated by a vacuum pump (not shown) and a compressed air pump (not shown). 17.18
is a switching valve for switching between the vacuum suction and compressed air. 23 is a screw type extruder, and the tip of this extruder 23 is inserted into the lower formwork 1 by means of a vibrator 24.
It communicates with the second molding recess 13a. 29 is a supply port for supplying the raw material slurry 30 to the screw extruder 23, and 25 is a motor that drives the screw of the screw extruder 23. What should be noted is the upper formwork 2 above.
In addition, a planar heating element 35 having a built-in heating wire (chrome wire) is installed in the lower formwork 12 to heat the entire mold, and the screw extruder 23
A hot wire 36 is wound around the outer periphery of the vibrator 24 extending from the vibrator 24 to heat the raw material slurry 30 that is extruded through it.

In this configuration, as shown in FIG. 1, with the mold closed, the molding recesses 3a, 1
The raw material slurry 30 is press-fitted into the molding space created in step 3a. And suction/compression vibrator 4 of upper mold and lower mold
, 14 performs vacuum suction, and the moisture in the raw material slurry 30 is suctioned and dehydrated. At this time, the raw material slurry 30 supplied into the molding space is heated in a vibrator 24 extending from the screw extruder 23, and when it is press-fitted into the molding space, the raw material slurry 30 is heated in the upper and lower mold frames 2. It is heated by a planar heating element 35 built in 12.

Therefore, the moisture in the raw material slurry 30 is quickly dehydrated, and the molding of the raw material slurry 30 is quickly completed.

When the molded rod is formed in this way, compressed air is discharged from the suction/compression vibrator 14 of the lower mold to separate the molded rod from the mold surface, and at the same time, the hydraulic cylinder 19 is actuated to move the upper mold to the upper mold. As shown in Figure 2, the mold is raised, and a molding rod holder plate (not shown) is inserted into the space between the upper mold and the lower mold. In this case, the suction/compression vibrator 4 of the upper mold maintains the suction state. Therefore, the molding rod 31 is raised while being sucked into the molding recess 3a of the upper mold.

Next, in this state, compressed air is fed into the suction/compression pipe 4 of the upper mold by switching the switching valves 7 and 8. As a result, the forming rod 31 falls from the mold surface of the upper mold into the tray. Then, the molded rod taken out into the tray is
When a plurality of pieces are collected, they are put into a curing device such as an autoclave or a baking furnace and hardened by baking and curing.

The results of the examples in which continuous casting was carried out in this manner are shown in the following table in comparison with the comparative examples in which casting was carried out without heating.

In both cases, the amount of dough is 10) cg, the thickness of the product is set to 10 mm, and the dehydration time is compared when making a raw material slurry containing 25% water into a molded product with a water content of 8% by weight. are doing.

(The following is a blank space) As is clear from the above table, it can be seen that in the example, the time required for dehydration can be reduced to about 1/3 of that of the conventional example.

In the above embodiments, the raw material slurry is heated in both the upper and lower mold frames and the raw material slurry supply vibrator, but the heating method is not limited to this. For example, when producing a raw material slurry, the water to be used may be heated in advance and then used, or the entire apparatus may be placed in a high temperature room or the like for work.

〔Effect of the invention〕

As described above, the present invention injects raw material slurry under pressure into the molding space of a molding die, applies vacuum suction to the raw material slurry under the pressure, and heats the raw material slurry at the same time. becomes dehydrated quickly. Therefore, even thick molded products can be molded in a short time.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus used in the present invention, and FIG. 2 is an explanatory diagram of its operation. l... Upper base board 2.12... Formwork 3.13...
Porous elastic body 3a, 13a... recess for molding 4, 1
4...Suction/compression vibe 24...Pipe 35.
... Planar heating element 36 ... Heat wire

Claims (1)

[Claims] (1) Using an upper mold and a lower mold, at least one of which has water permeability, raw material slurry is injected into the molding space created by both molds and dehydrated using the water permeability of the mold, and molded. This is a manufacturing method for inorganic products in which a product is made and then converted into an inorganic product through a curing process. A method for manufacturing inorganic products characterized by applying pressure and heat to a raw material slurry in a space.