JPH028882B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing an inorganic molded body, and is particularly suitable for producing an inorganic molded body having a long or thin wall portion such as a pipe by an isostatic pressing method. The present invention relates to a method for producing an inorganic molded body.

[Conventional technology] Traditionally, ceramic molding methods include:
Slime casting, extrusion, dry press molding, CIP
There are methods such as (Cold Isostatic Press) molding.
Among these, the CIP molding method uses a flexible mold and applies hydrostatic pressure (isotropic pressure), so there is no density unevenness within the molded product.
Therefore, it is an excellent molding method that has the advantages of being homogeneous with little distortion, and increasing molding density because high pressure can be applied. First of all, it is widely used.

[Problems to be Solved by the Invention] The CIP molding method involves filling a mold with raw material powder and subjecting it to isostatic pressure molding. When molding such a thin and elongated object, an inner mold (made of metal) 11 and an outer mold (made of rubber) 12 as shown in FIG. 3 are used. In this case, the gap 13 between the inner mold 11 and the outer mold 12 is
Since the gap 13 is narrow and long, it is extremely difficult to uniformly fill the forming raw material powder 14 into the gap 13.

Conventionally, in order to achieve uniform filling, it was necessary to improve the fluidity of the raw material powder for molding (for example, by using a spray dryer to create a smooth spherical powder).
Methods such as applying vibration using a vibrator etc. when filling the powder are used, but these are quite complicated processing operations, take a considerable amount of time in terms of workability, and require less equipment and equipment. From the surface etc.
The drawback was that manufacturing costs were high.

[Means for Solving the Problems] The method for producing an inorganic molded body of the present invention is a method for producing an inorganic molded body by isostatic pressing, in which one or more inorganic sheets are loaded into a mold. It is characterized by being hydrostatically pressed.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

The method of the present invention uses an inorganic sheet as a molding raw material when hydrostatic pressing is performed by CIP molding or the like.

That is, for example, when forming a thin cylindrical body 10 as shown in FIG. 2 by the method of the present invention,
Take out the inner mold (made of metal) 2 from a normal mold, wrap the inorganic sheet 1 around its side surface once, then load it into the rubber outer mold 3, seal it, and apply hydrostatic pressure using the usual method. Sprinkle and form.

At this time, the overlapping or abutting surfaces of both ends 1a of the inorganic sheet 1 wrapped around the inner mold are filled with water or the main component of the inorganic sheet used to ensure the adhesiveness of the joint. It is preferable to apply an aqueous solution or slurry of an inorganic substance, preferably with a binder added thereto, by spraying or brushing. When using an aqueous solution or slurry of an inorganic substance, its concentration is 0.
The concentration is preferably about 50% by weight, and examples of the binder to be added include PVA, MC, CMC, acrylic emulsion, starch, etc. The concentration of the binder is preferably about 0 to 5% by weight. When applying water or an aqueous solution or slurry of an inorganic substance in this way, it is preferable to dry and remove water after this application and before isostatic pressing.

Inorganic sheets used in the present invention include various ceramic papers such as ceramic paper (ceramic paper, ceramic paper (manufactured by Toyo Pulp Co., Ltd.)), alumina paper, mullite paper, aluminum hydroxide paper, silicon nitride paper, etc. Examples include all inorganic sheets such as gypsum paper and cement paper. These inorganic sheets can be prepared by conventional methods,
For example, by the method described in JP-A No. 61-40866, etc.
Easy to manufacture.

There is no particular limit to the thickness of these inorganic sheets, but if they are too thin, they will be difficult to handle.
In some cases, it may not be possible to easily produce a molded article with a desired shape. On the other hand, if the sheet is too thick, it may be difficult to wrap the sheet around the inner mold shown in FIGS. 1a and 1b. For this reason, the thickness of the inorganic sheet used is preferably about 0.2 to 3.0 mm.

When producing a relatively thick-walled molded body by the method of the present invention, for example, when producing a thick-walled cylindrical body, an inorganic sheet with a thickness approximately equal to the wall thickness is placed inside the molded body as shown in FIG. 1a. It may be formed by winding it around a mold, but as mentioned above, a thick inorganic sheet has poor winding properties, and a good molded product may not be obtained. Therefore, in such a case, as shown in the cross section in FIG.
It is preferable to wrap the inorganic sheets to the desired thickness so as not to overlap each other, and then to form the sheets.In this way, even when multiple inorganic sheets are wrapped in a layered manner,
The above-mentioned water or an aqueous solution or slurry of an inorganic substance is sprayed on the overlapping surfaces of the inorganic sheets 1 and 1', 1' and 1'', and the abutting surfaces of the end abutting parts 1a, 1'a, 1''a. It is preferable to apply by hanging or the like.

Although the case where a pressureless cylindrical body is manufactured by the method of the present invention has been described above, the method of the present invention is also effective when manufacturing a box-shaped body with a bottom.

For example, when manufacturing a box-shaped molded body 4 having the shape shown in FIG. 5, an inorganic sheet for the bottom surface is separately prepared in addition to the side surfaces, and the inside of the box-shaped body 4 of an appropriate shape is prepared as shown in FIG. An inorganic sheet for side surfaces 6 is wrapped around the side surface of the mold (medium size) 5, and an inorganic sheet for bottom surface 7 is provided at the bottom. In this case as well, on the abutting surfaces of the edges of the side inorganic sheet 6 and the abutting surfaces of the side inorganic sheet 6 and the bottom inorganic sheet 7,
Preferably, the above-mentioned water or an aqueous solution or slurry of an inorganic substance is applied.

After the inorganic sheets 6 and 7 are attached to the inner mold 5 in this manner, the box-shaped molded body 4 can be easily manufactured by loading the inorganic sheets 6 and 7 into the outer mold and applying hydrostatic pressure.

[Function] Since the method of the present invention uses an inorganic sheet instead of conventional powder as a raw material for isostatic pressing,
Unlike conventional methods, there is no problem with powder filling unevenness in areas with small cross-sectional areas, and the uniformity of the inorganic sheet is directly imparted to the resulting molded product, making it easy to produce uniform, high-quality molded products. Can be done.

This eliminates the need for processing to improve the fluidity of the powder or for filling equipment such as a vibrator, improving workability and reducing equipment costs, processing costs, and the like.

In addition, when molding a cylindrical object, etc., the shape of the molded object is determined to some extent by the inner mold and the inorganic sheet, so there is no need to require very high precision from the outer mold, and a mold with relatively low precision can be used. It becomes possible to manufacture highly accurate molded bodies.

The method of the present invention is particularly suitable for producing a molded body having a thin wall portion or a long portion, such as a cylindrical body such as a cylinder or a container body with a bottom.

[Examples] The present invention will be explained in more detail by Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example 1 A cylindrical body was manufactured by the method shown in FIGS. 1a and 1b.

Wrap ceramic paper (manufactured by Shikoku Paper Co., Ltd.) with a thickness of 1.5 mm evenly around a metal cylinder (29.4 mmφ x 294 mm), place it in a rubber mold, remove the air, seal it, and apply hydrostatic pressure at 2000 kgf/cm ² Molded. The dimensions of the obtained molded body are 29.4mmφ (inner diameter) x 294mm (length) x
It was 1.3mmt (thickness). This cylindrical molded body is 950
It was fired at ℃ for 1 hour to obtain a ceramic cylinder of 25 mmφ x 250 mm x 1.1 mmt. This ceramic cylinder was extremely uniform and of high quality.

Example 2 250 g of alumina powder, 250 c.c. of water, 1.3 g of polyacrylic dispersant, 27 g of allyl binder and 10 g of polyethylene lubricant were mixed and stirred, and further diluted with water to make an alumina slurry with a total weight of 1.0 kg. Prepared. To this alumina slurry, an approximately 15-fold diluted aqueous solution containing 16.7 g of a cationic fixer and an approximately 10-fold diluted aqueous solution containing 12.5 g of anionic fixative were sequentially added under stirring to obtain a slurry for papermaking. The obtained slurry for paper making was made into paper by a conventional method to obtain an alumina sheet (see JP-A-61-40866). This alumina sheet had a thickness of 1.4 mm and a green density of 2.25.

This alumina sheet was wrapped around a metal cylinder in the same manner as in Example 1. Then, as shown in FIG. 4, a second alumina sheet was wrapped around the first alumina sheet so that the seams did not overlap, and then a third alumina sheet was wrapped around the first alumina sheet. At this time, in order to make the adhesion between the alumina sheets more complete, the alumina slurry was sprayed onto the outer surface of the first alumina sheet, and the second alumina sheet was wrapped around it. The same procedure was applied to the third alumina sheet.

After drying this at 100°C for 5 hours, it was placed in a rubber mold, the air was removed, and the mold was sealed, followed by CIP molding at 2500 kgf/cm ² . The obtained molded body is 30mmφ×300mm×3.6
It was mmt. This molded body was fired at 1650°C for 2 hours to obtain a sintered body. This item is 25mmφ×250mm
It was a uniform and dense alumina sintered body with a thickness of 3.0 mm, a bulk specific gravity of 3.92, and a water absorption rate of 0%.

[Effects of the Invention] As detailed above, according to the method for producing an inorganic molded body of the present invention, it is possible to easily produce extremely uniform and high-quality molded bodies even if the molded body has a thin wall portion or a long portion. can do.

In addition, the production thereof does not require special equipment such as a vibrator or special processing of powder, and can be produced efficiently at low cost.

[Brief explanation of drawings]

FIGS. 1a and 1b are diagrams illustrating the method of forming a cylindrical body according to the present invention, in which a is a perspective view and b is a longitudinal cross-sectional view. Fig. 2 is a perspective view of the molded body, Fig. 3 is a longitudinal cross-sectional view illustrating a conventional molding method, Fig. 4 is a cross-sectional view showing an example of winding an inorganic sheet, and Fig. 5 is a perspective view of the box-shaped molded body. FIG. 6 is a perspective view showing an example of winding an inorganic sheet when manufacturing the box-shaped molded product shown in FIG. 5. 1, 1', 1''...Inorganic sheet, 2...Inner mold,
3...Rubber outer mold.

Claims (1)

[Scope of Claims] 1. A method for producing an inorganic molded body by isostatic pressing, characterized in that one or more inorganic sheets are loaded into a mold and subjected to isostatic pressing. manufacturing method. 2. The manufacturing method according to claim 1, wherein water or an aqueous solution or slurry of an inorganic substance is applied to the overlapping or abutting surfaces of the inorganic sheets.