JP2637678B2 - Drying method of ceramic cylindrical molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying method for obtaining a ceramic cylinder having excellent dimensional accuracy.

[0002]

2. Description of the Related Art In the production of a ceramic cylindrical body, conventionally, ceramic clay has been extruded and formed, and the formed body has been placed on a support table and left to stand in the air for 2 to 3 days to air dry. The dried product is often fired. However, since the ceramic cylindrical molded body immediately after extrusion molding is still soft, when the ceramic cylindrical molded body is placed on a support table and air-dried, the horizontal dimension becomes larger than the vertical dimension. In some cases, it was deformed into an elliptical shape.
In this case, even in the subsequent firing step, the distortion of the dimension is not corrected, and a fired body deformed into an elliptical shape is produced, which has been a problem. When drying the ceramic cylindrical molded body, in order to prevent such deformation, after placing the molded body on a support base, the temperature and humidity are dried in a dryer in which the temperature and humidity are adjusted. There was a way. A method is also known in which air is blown from the lower side of the ceramic cylindrical molded body immediately after extrusion molding to cause the ceramic cylindrical molded body to float, and at the same time, air is flown into the space inside the cylindrical molded body while being dried.

[0003]

However, depending on the particle size distribution of the clay, the moisture content of the clay, the type of ceramics, etc., when the ceramic cylindrical molded body is placed on a support and dried naturally, the vertical The present inventor has discovered for the first time that the dimension in the direction becomes larger than the dimension in the horizontal direction, and the shape is transformed into a vertically long elliptical shape. In addition, the present inventor, after placing the molded body on the support table, in a dryer in which the temperature and humidity were adjusted, tried drying the temperature and humidity, but again the above deformation could not be prevented, and the cross section was not able to be prevented. However, a dried product having a perfect circular shape could not be obtained.

Further, the present inventor has made the above-mentioned ceramic cylindrical molded body float by blowing air from the lower side of the cylindrical molded body, and at the same time, flowing air into the inner space of the cylindrical molded body. I tried drying. However, the above deformation could not be prevented, and a dried body having a perfect circular cross section could not be obtained. In addition, the drying method in which air is blown from the lower side of the cylindrical molded body to float it is not suitable for mass production at all and is not practical.

[0005] An object of the present invention is to prevent a large difference between a horizontal dimension and a vertical dimension when drying a large number of ceramic cylindrical molded bodies, thereby preventing deformation from a predetermined dimension. It is to provide an efficient drying method.

[0006]

According to the present invention, there is provided a method for drying a ceramic cylindrical molded body, comprising placing the ceramic cylindrical molded body on a support base, wherein the inner surface side of the ceramic cylindrical molded body is equal to the outer surface side. A gas is flowed at a flow rate of 10 m / sec or more into at least the inner space of the ceramic cylindrical molded body so as to dry faster.

[0007]

According to the present invention, the ceramic cylindrical molded body is placed on a support base, and when it is air-dried, or when the temperature and humidity are dried, the vertical dimension becomes larger than the horizontal dimension. Has been found to be transformed into an elliptical shape. First,
This phenomenon will be described. In the schematic diagram of FIG.
An inclined surface 4 is formed on each of the projections 3c of the support base, and the ceramic cylindrical molded body 1 is placed between a pair of opposed inclined surfaces 4. When the cylindrical molded body 1 is cut in the width direction, the horizontal dimension is a and the vertical dimension is b.

When the cylindrical molded body 1 is dried, a dried body 11 is obtained as shown in FIG. Here, depending on the particle size distribution of the clay, the moisture content of the clay, the type of ceramics, and the like, the vertical dimension b of the dried body 11 was larger than the horizontal dimension a, and was deformed into a vertically long elliptical shape. Moreover, the present inventor has found that the cylindrical molded product 1 can be formed even on a flat supporting surface.
Was subjected to a drying experiment, but was also transformed into a vertically long elliptical shape. Such deformation is also against the direction of gravity.

Here, the present inventor places the cylindrical molded body on a support base and places at least 10 mm in the inner space of the cylindrical molded body.
When a gas was flowed at a flow rate of m / sec or more so that the inner surface side of the cylindrical molded body dries faster than the outer surface side, it was found that the above-mentioned deformation was remarkably suppressed.
Although the cause is not clear, it is considered that uneven shrinkage can be suppressed by promoting drying of the inner surface of the cylindrical molded body at a stage where the water content is still large. Further, according to the drying method of the present invention, a large number of cylindrical molded bodies can be processed at the same time, which is extremely suitable for mass production.

[0010] When air is used as the gas flowing into the inner space of the cylindrical molded body, the cost can be reduced most. Further, gas may be supplied from a cylinder. The temperature of the gas may be from 10 to 80C, preferably from 20 to 60C. Heating the gas above room temperature can reduce the drying time.

Further, when the cylindrical molded body is dried until the moisture content of the dried body after drying becomes 9% by weight or less, the amount of deformation of the dried body is further reduced. If the moisture content at this time exceeds 9% by weight, when the dried body is left in the air, the deformation of the dried body proceeds somewhat.

[0012] It is more preferable that the primary dried body is further dried secondarily after the cylindrical molded body is primarily dried according to the present invention, from the viewpoint of preventing cracks during firing.

In particular, with respect to the following ceramics having strict dimensional accuracy, it has been found that the vertical dimension of the dried body becomes larger than the horizontal dimension and is deformed into a vertically long elliptical shape.

A stabilized or partially stabilized zirconia powder,
LaMnO ₃ , L with or without various additives
A cylindrical compact obtained by kneading a perovskite-based composite oxide powder such as aCrO ₃ , an alumina powder, a mullite powder and a binder, and molding. In particular, yttria-stabilized or partially-stabilized zirconia powder, La (Sr) MnO ₃ , La
(Ca) A cylindrical molded body obtained by kneading and molding a MnO ₃ powder and a binder.

Further, the particle size distribution of the clay is 0.1 to 20 μm.
And when the moisture content of the clay is 5 to 15%, the vertical dimension of the dried body becomes larger than the horizontal dimension,
It was found that it was transformed into a vertically long elliptical shape.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The support base used in the present invention is preferably provided with a plurality of elongated grooves, and the dimensions and shape of the grooves can be selected so that the ceramic cylindrical molded body can be placed in these grooves. The profile in the width direction of the groove may be an arc, a triangle, or the like. A support having a flat surface can also be used.

Hereinafter, more specific experimental results will be described. To 100 parts by weight of the yttria-stabilized zirconia powder having an average particle diameter D ₅₀ = 5 μm, 3 parts by weight of polyvinyl alcohol was added as a main binder, kneaded, and the water content was 1%.
2% by weight of a kneaded product was obtained. This was put into a vacuum kneader, and a cylindrical molded body having an outer diameter of 20 mm, a thickness of 2 mm, and a length of 1500 mm was extruded.

Next, the cylindrical molded body 1 was placed on the support 3 by a method schematically shown in FIGS. 1, 2 and 3, and the cylindrical molded body 1 was dried. The flat plate 3a of the support 3 is substantially rectangular, and a leg 3b is provided below the flat plate 3a. On the upper surface of the flat plate 3a, a projection 3 having a slender, triangular cross section in the width direction.
A plurality of c are provided substantially parallel to each other.

An inclined surface 4 is formed on each of the projections 3c, and the cylindrical molded body 1 is placed between a pair of opposed inclined surfaces 4. Note that the angle formed by the inclined surface 4 with the horizontal plane is preferably 15 to 75 degrees,
More preferably, the angle is 30 to 45 degrees. In the present embodiment, this angle is 45 degrees.

As shown in Table 1 below, air was flowed on the inner surface side and / or outer surface side of the cylindrical molded body 1 to perform drying. That is, Examples 1 to 4 of the present invention and Comparative Examples 5 and 8 shown in Table 1
In, air was flowed into the inner space 5 of the cylindrical molded body 1. Table 1 also shows the flow rate (m / sec) at this time. Invention Example 4
In Comparative Examples 7 and 8, air was caused to flow on the outer surface side of the cylindrical molded body 1. Table 1 also shows the flow rate (m / sec) at this time.

Table 1 shows the time (minutes) for flowing air. However, in Comparative Example 6, air was flowed for three days,
In Comparative Example 7, air was flowed for one day.

The dried body 11 after drying (see FIG. 4)
Was measured for the inner surface side, outer surface side, and the entire dried body 11 of the dried body 11, respectively. Dried body 1
The difference (amount of deformation of the dried body) ba (mm) between the horizontal dimension a and the vertical dimension b of 1 was measured. The number of measurements for each example was 10 and the average value is shown in Table 1.

Here, in an experimental example in which air was flowed into the inner space 5 of the cylindrical molded body 1, air was supplied as follows. Immediately after the cylindrical molded body 1 was placed on the support 3 as shown in FIG. 2, air was flowed inside the cylindrical molded body 1. At this time, as schematically shown in FIG. 1, one end of the flexible tube 7 was attached to the outlet of the blower 6, and the other end of the flexible tube 7 was attached to the distributor 8.

The dispenser 8 is provided with a plurality of nozzles 9. Opening 2 on the side of extrusion rear part 1b of cylindrical molded body 1
Nozzles 9 were inserted into B, respectively. When air is blown out from each nozzle 9, the air flows through the inner space 5 of the cylindrical molded body 1, and is extruded into the opening 2 </ b> A on the front part 1 a side.
Blew out from In this embodiment, the temperature of the air is set to 30 ° C.

[0025]

[Table 1]

As can be seen from Table 1, in Examples 1 to 4 of the present invention, air is caused to flow in at least the inner space 5 of the cylindrical molded body 1 so that the inner surface side of the cylindrical molded body 1 is dried at least as quickly as the outer surface side. Then, the amount of deformation of the dried body 11 (b−
a) was remarkably reduced to 0.15 mm or less.
On the other hand, in Comparative Example 5, although the air flow rate was 5 mm / sec, the amount of deformation (ba) of the dried body 11 was 0.18 mm.

On the other hand, in Comparative Example 6, although the cylindrical molded body 1 is naturally dried, the amount of deformation of the dried body 11 is large, and it takes three days to dry, so it is not suitable for mass production.
In Comparative Example 7, air was caused to flow on the outer surface side of the cylindrical molded body 1,
Although no air is flowed through the inner space 5, the drying body 11 is not suitable for mass production because the amount of deformation of the drying body 11 is large and drying takes time.

In Comparative Example 8, air is flown on the outer surface side and the inner space 5 of the cylindrical molded body 1. However, in the dried body 11, the moisture content is smaller on the outer surface side than on the inner surface side. And drying is progressing. As a result, the amount of deformation of the dried body 11 reaches 0.35 mm.

Note that La (Ca) MnO ₃ powder, La
(Sr) MnO ₃ powder, LaCrO ₃ powder or alumina powder and a binder were kneaded respectively. And about each cylindrical molded body obtained by molding each of these kneaded materials,
Experimental results similar to those described above were obtained. The present invention is also effective in the case where the horizontal dimension a of the dried body 11 becomes larger than the vertical dimension b and is deformed into a horizontally long elliptical shape.

[0030]

As described above, according to the present invention, when the ceramic cylindrical molded body is dried, a difference is generated between the horizontal dimension and the vertical dimension of the dried body, and a predetermined value is obtained. Deformation from dimensions can be prevented. Moreover, according to the drying method of the present invention, a large number of cylindrical molded bodies can be dried at the same time, which is very suitable for mass production.

[Brief description of the drawings]

FIG. 1 supplies gas to an inner space 5 of a cylindrical molded body 1,
FIG. 3 is a plan view schematically showing a dry state.

FIG. 2 is a perspective view showing a state in which a plurality of cylindrical molded bodies 1 are mounted on a support 3;

FIG. 3 is a front view schematically showing a state in which a plurality of cylindrical molded bodies 1 are mounted on a support 3;

FIG. 4 is a front view schematically showing a state in which the dried body 11 is placed on a support 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical molded body 2A, 2B opening 3 Support stand 5 Inside of cylindrical molded body 11 Dry body a Horizontal dimension of dry body 11 b Vertical dimension of dry body 11

Claims (4)

(57) [Claims] 1. A ceramic cylindrical molded body is placed on a support, and at least an inner space of the ceramic cylindrical molded body is dried so that an inner surface side of the ceramic cylindrical molded body is dried at least as quickly as an outer surface side. A method of drying a ceramic cylindrical molded body, characterized by flowing a gas at a flow rate of 10 m / sec or more. 2. The ceramic tubular molded body according to claim 1, wherein the ceramic cylindrical compact is at least one ceramic powder selected from the group consisting of stabilized zirconia powder, partially stabilized zirconia powder, lanthanum manganate powder, lanthanum chromite powder, alumina powder, and mullite powder. The method for drying a ceramic tubular molded body according to claim 1, wherein the ceramic tubular molded body is obtained by kneading and molding a binder and a binder. 3. A method according to claim 1, wherein the particle size distribution of the clay forming the ceramic cylindrical molded body is 0.1 to 20 μm, and the water content of the clay is 5 to 15%. 3. The method for drying a ceramic cylindrical molded body according to 1 or 2. 4. A ceramic cylindrical molded body is placed on a support table, and at least an inner space of the ceramic cylindrical molded body is dried so that an inner surface side of the ceramic cylindrical molded body is dried at least as quickly as an outer surface side. A method for drying a ceramic tubular molded body, comprising: obtaining a primary dried body by flowing a gas at a flow rate of 10 m / sec or more through the air, and then secondary drying the primary dried body.