JP2000026155A - Production of ceramics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain ceramics having a nearly prescribed shape with slight deformation by disposing a heat resistant jig having a prescribed shape in a hollow conical compact formed by compacting a powdery starting material, putting them in a firing furnace and firing the compact while supporting it by the jig. SOLUTION: A powdery starting material for ceramics is compacted through a high pressure liq. or the like to form a hollow conical compact 1 similar in shape to a product. This compact 1 is disposed on a plate 5 and a heat resistant jig 3 whose shape coincides with the inside shape of the compact 1 after firing is disposed in the compact 1. The material of the jig 3 is required not to cause deformation and reaction with the compact at a high firing temp. The plate 5 is put in a firing furnace and the compact 1 is fired by heating. Even if the compact 1 is deformed by ununiform heat conduction from a heat source during the firing, the fired compact in a hot soft state is formed in the shape of the jig 3 by gravity and the objective ceramics 2 having a prescribed shape is obtd. with slight deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ceramics.

[0002]

2. Description of the Related Art FIG. 5 is a view showing a conventional method for producing ceramics. First, FIG. 5 will be described. First, in a raw material blending step (a), a predetermined amount of powder, water or a solvent, and a small amount of additives are blended in a ceramic raw material, and then, in a mixing step (b), a large number of balls for mixing are included. The container is kneaded by a rotating ball mill to form a uniform slurry. This slurry is sprayed by a spray drying device in a granulation step (c) and dried with hot air to form an aggregate of powder having high fluidity (hereinafter referred to as granules). In the next molding step (d), the granules are poured into a molding die having a combination of a rubber outer frame and a metal core, and pressed from outside the rubber die in a high-pressure liquid to compact the powder. To form a lump (hereinafter referred to as a compact) of the raw material powder having a hardness of about chalk. The formed body is processed into a shape close to a product in a formed body processing step (e), and then fired in a firing step (f) at a high temperature of usually 1000 ° C. or more for one to several days to obtain a ceramic having predetermined characteristics. (Hereinafter called a fired body) is completed. Thereafter, final processing, polishing or surface treatment is performed in the finishing step (g) as necessary.

Here, the firing step (f) will be described in more detail with reference to FIG. FIG. 6A is a view showing the inside of the firing furnace 6, and shows a state in which the hollow conical shaped body 1 placed on the base plate 5 before firing is fired. FIG. 6B is a diagram showing a relationship between a molded body before firing and a fired body after firing. In this step, in the process of receiving the heat 7 from the heat source and increasing the temperature of the molded body, the particle spacing gradually approaches (hereinafter referred to as sintering), and finally the dimensions are several percent to ten and several percent apparently. The sintered body becomes smaller (hereinafter referred to as shrinkage) and the process is completed. Electricity or gas is used as a heat source. Shrinkage proceeds as the temperature rises, and is almost completed before and after reaching a set maximum temperature. At that stage, the fired body is in a state of being softer than normal temperature.

[0004]

In the conventional method, the base plate 5 is used.
When the heat 7 was slightly unevenly transmitted, the shrinkage progressed with a time difference in the same molded body, resulting in unevenness in dimensions. As a result, as shown in FIG. 6B, there was a problem that the sintered body 2 was deformed at the stage where sintering was completed, and a predetermined shape could not be obtained. In addition, even after sintering is completed, the fired body maintains a soft state at high temperatures, so even if there is a slight inclination, the effect is greatly amplified by its own weight, which further promotes deformation. Had. These tendencies were remarkable in a molded article having a large hollow shape, particularly a thin wall shape. In addition, there is also a problem that a large amount of labor is required since the deformation requires additional processing after firing.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and when firing a hollow conical shaped body,
It is an object of the present invention to obtain a ceramic product having a shape close to a predetermined shape by firing while supporting with a heat-resistant jig having a shape after firing.

[0006]

According to a first aspect of the present invention, there is provided a ceramic for firing a molded body in a state in which a heat-resistant material having a shape corresponding to the inner surface shape after firing is arranged inside a hollow conical shaped body. It is a manufacturing method.

Further, a second invention is a method for producing a ceramic in which a formed body is fired in a state in which a heat-resistant material having a shape corresponding to the shape of the outer surface after firing is arranged outside the hollow conical shaped body. .

In a third aspect of the present invention, a heat-resistant material having a shape corresponding to the shape of the outer surface after firing is placed in an inverted state,
This is a method for producing ceramics in which a hollow conical shaped body that is inverted is fired.

In a fourth aspect, a heat-resistant material having a shape corresponding to the shape of the outer surface after firing is placed in an inverted state,
This is a method for producing ceramics in which a fired ball is baked in a state in which a weight of a heat-resistant ball is included in a hollow conical shaped body inverted therein.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1A is a view showing a state before firing, and shows a state in which a hollow conical shaped body 1 is placed on a base plate 5. FIG.
(B) is a figure which shows the state after baking. In this step, if the heat transfer from the heat source to the molded body 1 is somewhat non-uniform in the process of increasing the temperature by receiving the heat from the heat source, deformation occurs in the process of sintering. However, at the stage where the sintering is completed and the temperature is maintained at a high temperature, the fired body is still sufficiently soft, so that the weight of the heat-resistant material disposed therein is reduced by its own weight, and the fired body 2 of the ceramic has a predetermined shape with little deformation. Can be obtained. As a result, the labor required for the finishing process can be minimized.
The material of the heat-resistant jig is not limited as long as it does not deform at high temperature during firing and does not react with the fired body.

Embodiment 2 FIG. 2A is a view showing a state before firing, and shows a state in which a hollow-cone-shaped molded body 1 is placed on a base plate 5. FIG. 2B is a diagram showing a state after firing. In this step, if the heat transfer from the heat source to the molded body 1 is somewhat non-uniform in the process of raising the temperature by receiving the heat from the heat source, deformation occurs in the process of sintering. However, at the stage where sintering is completed and held at high temperature, the fired body is still sufficiently soft,
Due to the weight of the heat-resistant jig placed outside, the outer surface of the fired body follows the inner shape of the heat-resistant jig processed to the correct dimensions.
Ceramic sintered body 2 with a predetermined shape with little deformation
Can be obtained. As a result, the labor required for the finishing process can be minimized. In addition, according to the experiment of the applicant, it has been found that when the load of the heat-resistant jig is too heavy, the load applied to the fired body becomes too large, and as a result, a crack at the hem portion is generated. The weight is desirably within three times the weight of the molded body. The material of the heat-resistant jig is not limited as long as it does not deform at high temperature or reacts with the fired body during firing.

Embodiment 3 FIG. 3A shows a state before firing, and shows a hollow conical shaped body 1 before firing.
Are placed upside down and are fired to form a fired body. FIG.
(B) is a figure which shows the state after baking. In this step, if the heat transfer from the heat source to the molded body 1 is somewhat non-uniform in the process of increasing the temperature by receiving the heat from the heat source, deformation occurs in the process of sintering. However, at the stage where sintering is completed and held at a high temperature, the fired body is still sufficiently soft, so that the shape of the heat-resistant jig 3 arranged outside is reduced by its own weight. The body 2 can be obtained. As a result, the labor required for the finishing process can be minimized. The material of the heat-resistant jig is not limited as long as it does not deform at high temperature during firing and does not react with the fired body.

Embodiment 4 FIG. 4A is a view showing the inside of a firing furnace, in which a hollow conical shaped body 1 before firing is placed upside down and turned into a fired body by firing. It is shown. FIG. 4 (b)
Is a view of this from above. In this step, if the heat transfer from the heat source to the molded body 1 is somewhat non-uniform in the process of increasing the temperature by receiving the heat from the heat source, deformation occurs in the process of sintering. However, at the stage where sintering is completed and held at a high temperature, the fired body is still sufficiently soft and a uniform load is applied from the inner surface by the heat-resistant ball,
The weight of the heat-resistant ball 4 and the weight of the fired body itself follow the shape of the heat-resistant jig 3 disposed outside, and the fired body 2 of ceramics having a predetermined shape with little deformation can be obtained. As a result, the labor required for the finishing process can be minimized. The material of the heat-resistant jig and the heat-resistant ball is not limited as long as it does not deform or react with the fired body at the time of firing. According to the experiments conducted by the applicant, when the amount of the heat-resistant ball is too large, the load applied to the fired body becomes too large, and as a result, problems such as cracks and cracks occur. It is desirably less than twice.

[0014]

According to the first aspect of the present invention, even if the temperature distribution of the firing furnace is uneven and deformation occurs during the sintering process, when the fired body is softened at the time of holding at a high temperature, the heat-resistant material disposed inside is It becomes possible to obtain a ceramic fired body having a predetermined shape with little deformation due to its own weight according to the shape of the jig. As a result, the labor required for finishing can be minimized.

According to the second aspect of the present invention, even if the temperature distribution of the firing furnace is non-uniform and deformation occurs during the sintering process, when the fired body is softened at the time of holding at a high temperature, the heat-resistant material disposed inside is It becomes possible to obtain a ceramic fired body having a predetermined shape with little deformation due to its own weight according to the shape of the jig. As a result, the labor required for finishing can be minimized.

According to the third aspect of the present invention, even if the temperature distribution of the firing furnace is non-uniform and deformation occurs during the sintering process, when the fired body is softened at the time of holding at a high temperature, the heat-resistant material placed outside The fired body inverted to the shape of the jig is under its own weight,
It is possible to obtain a ceramic fired body having a predetermined shape with little deformation. As a result, the labor required for finishing can be minimized.

According to the fourth aspect of the present invention, even if the temperature distribution of the firing furnace is non-uniform and deformation occurs during the sintering process, when the fired body is softened at the time of holding at a high temperature, the heat-resistant material disposed inside is The weight of the heat-resistant ball in which the fired body inverted to the shape of the jig is incorporated is equal to the weight of the heat-resistant ball, and it is possible to obtain a fired body of the ceramic having a predetermined shape with little deformation.
As a result, the labor required for finishing can be minimized.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of a ceramic manufacturing method according to the present invention.

FIG. 2 is a view showing a second embodiment of the method for producing ceramics according to the present invention.

FIG. 3 is a diagram showing a third embodiment of the method for producing ceramics according to the present invention.

FIG. 4 is a view showing a fourth embodiment of the method for producing ceramics according to the present invention.

FIG. 5 is a general flow of manufacturing a ceramic product.

FIG. 6 shows a conventional method for producing a fired ceramic body.

[Explanation of symbols]

1 molded body, 2 fired body, 3 heat-resistant jig, 4 heat-resistant ball, 5 base plate, 6 firing furnace, 7 heat.

Claims (4)

[Claims] 1. A fired body is fired in a state in which a heat-resistant jig having a shape corresponding to the inner surface shape after firing is arranged inside a hollow conical shaped body in which raw material powder is compacted. Manufacturing method of ceramics. 2. The method according to claim 1, wherein the compact is fired in a state where a heat-resistant jig having a shape corresponding to the shape of the fired outer surface is arranged on the outer surface of the hollow conical compact obtained by compacting the raw material powder. Manufacturing method of ceramics. 3. A method in which a heat-resistant jig having a shape corresponding to the shape of the outer surface after firing is placed in an inverted state, and a hollow conical shaped body in which raw material powder is compacted therein is fired in an inverted state. Manufacturing method of ceramics characterized by the following. 4. A heat-resistant jig having a shape corresponding to the shape of the outer surface after firing is placed in an inverted state, and a hollow conical shaped body in which raw material powder is compacted is placed in an inverted state, and placed inside thereof. A method for producing ceramics, characterized in that firing is performed in a state in which a weight of a heat-resistant ball is included.