JPH0524937A - Method for calcining cylindrical ceramics - Google Patents

Abstract

PURPOSE:To calcine cylindrical ceramics having good dimensional accuracy at a good yield. CONSTITUTION:A green body 10 is molded to a blind cylindrical shape and plural pieces of scores 11 are formed thereon to form cut bodies 12, 13. The cutting bodies are dried and calcined in the state of stacking the cut bodies 12, 13 in such a manner that the cut body 13 exists lowermost. The lowermost cut body 13 receives the force to restrain shrinkage from a base 2 in this way. Since the cut body 13 is of a dish shape, the shrinkage force on calcination is extremely large and the cutting body shrinkes freely by overcoming this restraining force. Consequently, the calcined body having the regulated shrinkage rate on calcination is obtd. The respective cut bodies 12 on the upper side thereof are also made into the calcined bodies at the regulated shrinkage rate on calcination. The cylindrical ceramics having the extremely good dimensional accuracy are thus produced at the good yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for firing a cylindrical ceramic (either a long cylinder or a short cylinder such as a ring).

[0002]

2. Description of the Related Art When firing cylindrical ceramics, conventionally, a green body 1 formed in a cylindrical shape as shown in FIG. 5 is placed on a base 2 so that the cylinder axis direction is the vertical direction. It is dried and baked. The vertical direction of the cylinder axis is to prevent the green body 1 from being distorted by gravity. When firing ring-shaped or frame-shaped ceramics, as shown in FIG. 7, a plurality of cylindrical ceramic green bodies 1 are sliced and stacked to be fired. Reference numeral 3 in FIG. 7 indicates a cut. Further, reference numeral 4 indicates a cut body cut by the cut line 3.

[0003]

As shown in FIG. 5, when the green body 1 is fired with the cylinder axis direction being the vertical direction, since the lower end of the green body 1 is in contact with the base 2, shrinkage is restricted. As shown in FIG. 6, the lower end portion 5a of the sintered body 5 becomes distorted.

Incidentally, as shown in FIG. 7, when the green body 1 in which the cut bodies 4 are stacked is sintered, similarly, the cut body 4 (4a) arranged at the bottom is fired by the base 2. Since the contraction is restricted, there is a problem that the shape becomes distorted.

[0005]

A method for firing a cylindrical ceramic according to the present invention is a method of drying a green body formed into a tubular shape and then firing the green body, wherein the green body has a bottomed tubular shape with one end sealed. Into a plurality of cut bodies by cutting the green body in a direction perpendicular to the axis of the cylinder, and cut each of the cut bodies in the cylinder axis direction with one end of the green body at the bottom. It is characterized in that they are stacked and dried and baked in this state.

[0006]

In the method of firing a cylindrical ceramic according to the present invention, the cut body arranged at the bottom of the green body formed by stacking a plurality of cut bodies has a plate shape or a plate shape. .. Such a plate-shaped or plate-shaped green body has an extremely large shrinking force during firing shrinkage. Therefore, even if the green body is placed on the base and receives a force that restrains the firing shrinkage, Overcomes the force and almost freely shrinks by firing. As a result, each green body is uniformly fired and shrunk, and the tubular ceramics with high dimensional accuracy are fired.

[0007]

EXAMPLES Examples will be described below with reference to the drawings. 1 and 2 show an embodiment in which long cylindrical ceramics are fired. In this embodiment, a bottomed tubular green body 6 having a long tubular shape and one end side sealed is formed, a cut 7 is made along the bottom portion 6a of the green body 6, and a tubular cut body 8 is formed. And a dish-shaped cut body 9. The cut bodies 8 and 9 are stacked so that the cut bodies 9 are on the lower side, placed on the base 2, dried and fired. In this case, even if the plate-shaped cutting body 9 receives a force for restraining the firing shrinkage from the base 2, the dish-shaped cutting body 9 overcomes the restraining force and is almost freely fired and shrinkable. As a result, each of the cut bodies 8 and 9 contracts at the specified firing contraction rate, and becomes a fired body having a predetermined size.

3 and 4 show an embodiment in which a ring-shaped or frame-shaped cylindrical ceramic is fired. In this embodiment, a plurality of cuts 11 in the direction perpendicular to the cylinder axis direction are formed in a bottomed cylindrical green body 10 having a rectangular cylinder shape and one end side sealed, whereby a plurality of green bodies 10 are formed. It is composed of individual cutting bodies 12, 13. The cut bodies 12 and 13 are dried and fired in a stacked state such that the plate-shaped cut body 13 on the one end side of the green body 10 is at the bottom. Also in this embodiment,
The dish-shaped cutting body 13 overcomes the restraining force received from the base 2 and almost freely fires and shrinks, and the upper cutting body 12 also freely fires and shrinks. As a result, the tubular ceramics with the specified dimensions, which are fired at the specified firing shrinkage, are fired.

Although the prismatic green body is shown in FIGS. 3 and 4, it may be cylindrical. Further, in FIGS. 1 and 2 as well, the shape is not limited to the cylindrical shape, and may be a rectangular tube-shaped green body.

It should be noted that when firing the green body, a usual ceramic firing technique such as laying ceramic powder such as alumina on the base 2 in order to prevent fusion of the green body and the base is used in the present invention. Needless to say, it is also applicable in.

The above embodiment is an example of the present invention, and the shape of the green body and the number of cuts are not limited to those shown in the drawings. Further, a plate-shaped cut body may be used instead of the dish-shaped cut body.

[0012]

As described above, according to the method for firing cylindrical ceramics of the present invention, it is possible to fire cylindrical ceramics having good dimensional accuracy. Also, the firing yield is extremely high.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example method.

FIG. 2 is a vertical sectional view showing an example method.

FIG. 3 is a perspective view showing another embodiment method.

FIG. 4 is a vertical sectional view showing another embodiment method.

FIG. 5 is a perspective view showing a conventional example.

FIG. 6 is a longitudinal sectional view of a main part showing a conventional example.

FIG. 7 is a perspective view showing another conventional example.

[Explanation of symbols]

 6 Green body 7 Cut 8, 9 Cut body 10 Green body 11 Cut 12, 13 Cut body

Claims (1)

Claim: What is claimed is: 1. A green body formed into a tubular shape is dried and then fired, and the green body is formed into a bottomed tubular shape with one end sealed. In addition to cutting into a plurality of cut bodies by cutting in the direction perpendicular to the axial center, each cut body is placed in a state of being stacked in the cylinder axis direction with one end side of the green body at the bottom, and in this state. A method for firing cylindrical ceramics, which comprises drying and firing.