JPH0153604B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for manufacturing ceramics, and in particular uses a mold for hollow double-walled ceramics, and the mold is made of a self-water-absorbing material made of a porous material such as gypsum. The present invention relates to a casting method and apparatus using the same.

In the conventional casting method for manufacturing ceramics, a molding material called plastic slurry, which is made by mixing water with crushed porcelain clay or clay, or a deflocculant, which is a mixture of water glass and soda carbonate instead of water, is used. Pour the molding material into a slurry using a mold, such as a plaster mold, and let it stand for a while. When a thin layer of base material forms on the inner surface of the mold, drain the remaining molding material slurry inside. A method called sludge casting, in which the molded product is removed from the mold once the base material has hardened, was often used.

However, in the above conventional method, the molding material (sludge) is attached to the inner surface of the mold only by the self-absorbing property of the plaster mold, so the time required to form the base layer is usually
It took 45 minutes to 1 hour, and large numbers of molds were required for mass production. Furthermore, since a mold usually has multiple split molds, the molding material poured into the mold will flow toward the gaps over time, resulting in a directional pattern in the resulting molded product. When a molded product is fired, for example, a cylindrical product becomes eccentric, which causes deformation. Furthermore, it has been difficult to form threads, etc., on the mouth of the container, which requires high molding precision, for example.

The present invention aims at shortening the molding time by using a method and apparatus for producing ceramics that eliminate the above-mentioned drawbacks, is suitable for mass production, and the resulting ceramics do not deform even after firing. This made it possible to obtain a product with high strength.

The purpose of the present invention is to obtain a molded product from slurry specifically for manufacturing hollow double-walled ceramics, and the ceramics after firing are much lighter than they appear, and have sufficient strength. This method enables shortening of work time and mass production, and is generally based on a manufacturing method called casting molding, which forms the outer circumferential wall, bottom surface, and entire inner circumferential wall of the vessel to be made into a product. The key point is to use a hollow, double-walled mold for manufacturing pottery made of split molds. Sludge is fed into the hollow cavity of this mold through a downward facing gate, pressurized for a predetermined period of time, and then compressed air is released from an air pipe. This operation is repeated several times to coagulate the slurry to a predetermined thickness on the inner wall of the cavity. A stretchable membrane is fixed at its lower edge only at the lower end of the inner wall of a bell-shaped outer frame, and this outer frame is fitted onto the outer periphery of a molding base placed on a molding die and placed on the molding table. and the gate is aligned so that the slurry is fed into the mold through the gate. At this time, compressed air is sent from the air supply pipe at the top of the outer frame between the inner wall of the outer frame and the membrane, and the membrane surrounds the outer periphery of the mold under pressure, thereby creating an external pressure higher than the internal pressure of the mold. The mold will now be fixed. After agglomerating the slurry to a predetermined thickness, the air pipe at the top of the outer frame is switched to suction, the membrane inside the outer frame is sucked against the inner wall of the outer frame, and the mold is released;
The outer frame is pulled upward and then divided to take out the molded product.

The device and its operation will be explained below by means of the illustrated embodiment.

FIG. 1 is an explanatory view showing an example of a split mold for hollow double-walled ceramics according to the present invention. The mold 1 has two split molds A and A' that form the outer periphery of the vessel, and the bottom surface. The cavity 2 is formed by four split molds: one split mold B and a split mold C that forms the entire inner peripheral surface of the vessel. FIG. 2 is an explanatory diagram showing the PP cross section of FIG. 1,
FIG. 3 is an explanatory cross-sectional view of the molded product D, in which _D1 is a hollow portion constituted by a double wall.

FIG. 4 is an explanatory diagram of an apparatus for manufacturing a molded product having a hollow double wall using this mold 1, and FIGS. 5 to 7 are explanatory diagrams of the manufacturing operation. 3 is a gate for feeding and discharging slurry, 4 is a molding table, 5 is a gate of the molding table, and 16 is a molding pedestal, on which the mold 1 is set. 17 is a molded pedestal 16
The gates 3, 17, and 5 are overlapped to form a penetrating state. This gate is mud b
A conduit 6 for introducing and discharging is connected from below.
Below this conduit 6, a slurry injection pipe 7 and a slurry discharge pipe 8 are branched at a slightly different position, and each branch point has an injection valve 9 and a discharge valve 1.
0 is set. An air pipe 11 is provided through the center of the conduit 6, and a check valve 12 is provided at the tip of the air pipe 11.

A bell-shaped outer frame 13 is provided above the molding table so as to be movable up and down, and a membrane 14 is disposed on its inner wall, the lower edge of which is fixed only at the lower edge of the inner surface of the outer frame 13. At the top of the outer frame 13, an air supply pipe 15 for pressurizing and depressurizing air is provided.

In order to manufacture a hollow double-walled molded product using this device, first place the mold 1 on the molding pedestal 16 as shown in FIG.
and then place this pedestal 16 on the molding table 4.
The gates are overlapped and set in a penetrating shape.
Next, the outer frame 13 is lowered as shown in FIG. 5, and the outer circumference of the molding pedestal 16 is fitted and covered with the inner peripheral wall at the lower end. Next, by pressurizing compressed air a from the air supply pipe 15 at the top of the outer frame 13 between the inner wall of the outer frame and the membrane 14, the membrane surrounds the outer periphery of the mold 1, and this membrane 14
The mold 1 is always pressurized with a pressure higher than its internal pressure.

The membrane is not a thin film like that used in comb balloons, and its shape does not match the shape of the outer surface of the mold, nor does it tightly cover the entire outer surface of the mold. The membrane that holds the mold when compressed air is injected has an inner surface that is wider than the outer surface of the mold, so when pressurized, this membrane folds, overlaps, or flexes around the mold. etc. As a result, a small gap is created between the outer surface of the mold and the wrinkled portion of the film that has been folded, overlapped, or bent.
When the air inside the cavity is pressurized, the air inside the cavity leaks through the mold to the outer surface of the mold, and the leaked air passes through the gap and connects the lower end of the outer frame 13 and the mold. Pedestal 1
It is provided so that it passes through a slight gap between the two and exits outward.

In this state, the slurry b is injected into the cavity 2 of the mold 1 through the conduit 6 through the slurry injection pipe 7, by opening the injection valve 9 and through the gate.

Here, as a method of injecting slurry, the injection valve 9
After adjusting the opening of the slurry and injecting it under low pressure to make it thinly aggregate on the inner surface of the mold 1, the pressure outside the mold is increased and the injection pressure of the slurry is set to high pressure.
By maintaining this high pressure state for a certain period of time, the density of the slurry is increased and the slurry is coagulated to a desired thickness.

When feeding slurry b, the air that entered the pores of the mold itself and the air that entered the cavity 2 are:
After passing through the mold 1, it flows into the gap formed between the outer surface of the mold and the membrane and flows outward, as described above. When the slurry b is fed into the mold, the mold continues to absorb water from the slurry until the pores of the mold are filled with water. The absolute amount of water supplied to the mold as a whole is usually several times more than the amount of water that should be removed from the molded product, for example, even if part of the outer surface of the mold is tightly covered. The water absorption effect is sufficiently performed by the movement of air between the pores.

Then, compressed air is supplied from the air pipe 11,
At the same time as this compressed air is supplied, the discharge valve 10 is opened. When the discharge valve 10 is opened in this way, the area around the gate temporarily becomes negative pressure, so the cavity 2
Excess sludge inside is drained out. However, when the inside of the cavity 2 is narrow, it is not possible to exhaust everything in one operation, so the exhaust valve 10 is closed, compressed air is supplied from the air pipe 11, and after a certain period of time, the supply of compressed air is stopped and at the same time the exhaust valve 10 is closed. open. By repeating this operation several times, excess slurry is discharged little by little, and finally, compressed air is supplied and the discharge valve 10 is opened to discharge all of the slurry. Next, by evacuation from the top air pipe between the outer frame 13 and the membrane 14 and subsequent suction to reduce the pressure, the membrane 14 becomes the state shown in FIG. By raising the outer frame 13 in this state, the mold 1 is released from the external pressure, the split mold is divided, and the molded product is taken out. The outer frame can be raised and lowered using an air cylinder or a hydraulic cylinder.

The method for producing ceramics of the present invention uses the above-mentioned apparatus, and is particularly capable of producing hollow ceramics with double walls.The inside of the cavity is kept in a high-pressure state with slurry for a certain period of time, so it is extremely efficient. The thickness can be made uniform. The internal pressure within the cavity is preferably increased in two or three stages, and accordingly, the external pressure through the membrane of the outer frame must always be kept higher than the internal pressure of the cavity.

As for the slurry, thick cream-like slurry suspended in clay, clay, or sodium silicate may be used.

The present invention makes it possible to significantly shorten the molding time to obtain the desired wall thickness of the molded product, and because the slurry in the cavity is maintained at high pressure, the particles of molding material reach the joint between the split molds. There is no directionality in the arrangement, and the density of the molded product becomes larger and more uniform, improving its strength. This makes it possible to create large, dish-shaped containers, tall vases, etc., which were previously difficult to create, as well as hollow, lightweight containers. Unusual ceramics were created, with no deformation after firing, with high dimensional accuracy, and with great density and strength. In addition, it became possible to mold vessels into free and complex shapes, create hollow ceramics, and reduce weight.

With the present invention, conventional manual work and muscular work involving heavy objects can be easily automated, and even women and women can easily mold by simply operating a switch, resulting in uniform product quality, quality control, shortening of molding cycles, and improved quality. This made mass automated production possible.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of a split mold for a container with a hollow double wall used in the present invention, Fig. 2 is a sectional view taken along line P-P in Fig. 1, and Fig. 3 is an explanatory diagram showing an example of a split mold for a container having a hollow double wall used in the present invention. FIG. 4 is an explanatory diagram of the molded product, FIG. 4 is an explanatory diagram of the apparatus for manufacturing the present invention, FIGS. 5 to 7 are schematic diagrams showing the steps of the ceramic molding method of the present invention, and FIG. FIG. 6 is an explanatory diagram showing the injection process, FIG. 6 is an explanatory diagram showing the pressurization process, and FIG. 7 is an explanatory diagram showing the slurry discharge process. A, A', B, C...each split mold of the mold, D...
Molded product with hollow double walls, D ₁ ...
The hollow part, 1... mold, 2... mold cavity, 3, 5, 17... gate, 4... molding table, 6... conduit, 7... slurry injection pipe, 8... slurry discharge Pipe, 9... Injection valve, 10... Discharge valve, 11... Air pipe, 12... Backflow prevention valve,
13...Outer frame, 14...Membrane, 15...Air pipe, 1
6... Molding base, a... Compressed air, b... Sludge.

Claims (1)

[Claims] 1. When molding a mold by injecting a slurry of a molding material into a mold made of a porous material that has self-water absorbing properties, a flexible membrane such as rubber that spreads along the inner wall is attached to the lower edge of the mold. The mold is set on a molding base so that the bell-shaped outer frame fixed thereon can be inserted into the outer edge of the molding base, which is fixed on the molding base with its gate facing downward, and the above-mentioned Pressurized air at least higher than the internal pressure of the mold is sent between the outer frame and the membrane to completely pressurize and cover the outer periphery of the mold with the membrane, and the mold is used to cover the outer peripheral wall, bottom surface, and lower surface of the molding device. This is a hollow, double-walled mold for making utensils, which is made up of split molds that form the entire inner peripheral wall of the utensil.After feeding slurry from the gate into the hollow cavity of the mold under external pressure from a membrane, the slurry is pressurized for a predetermined period of time, and After coagulating the slurry to a predetermined thickness on the inner wall of the mold, the slurry other than the one coagulated on the inner wall of the mold is discharged with air.This operation is repeated several times to coagulate the slurry to a predetermined thickness, and then the mold is removed. After draining excess slurry from the membrane, the membrane is sucked into the inner wall of the outer frame by reducing the pressure between the outer frame and the membrane, the outer frame is raised, the mold is dissolved from the membrane, and the split molds are divided. A method for manufacturing hollow double-walled ceramics, characterized by removing the molded product. 2. When molding a vessel by injecting a slurry of molding material into a mold, the mold made of a porous material with self-absorbing properties forms the outer circumferential wall, bottom surface, and entire inner circumferential wall of the vessel. A mold for making hollow double-walled utensils consisting of a mold (hereinafter simply referred to as a mold)
The mold is stacked on a molding table and a molding pedestal placed on top of the molding table, with all gates penetratingly aligned, and this gate is connected to a slurry conduit leading from the bottom of the molding table into the gate. A slurry injection pipe and a slurry discharge pipe are connected to each other near the lower end of the pipe, and each branch point is provided with an injection valve and a discharge valve, respectively, and a pipe for supplying compressed air into the mold through the pipe. An air pipe is provided, and on the molding table there is provided a bell-shaped outer frame that covers the inner wall and is movable up and down and has a flexible membrane such as rubber that is fixed only at the lower end of the inner periphery. A ventilation pipe for supplying compressed air is provided at the top between the membrane and the outer frame so that the membrane fits into and covers the outer periphery of the molded pedestal, and when the membrane is fitted into the molded pedestal, compressed air is supplied. A ceramic manufacturing apparatus having a hollow double wall that can be fed between a membrane and an outer frame to surround the outer periphery of the mold via the membrane and pressurize it.