JPS6212196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for hot forming ceramic products.

Ceramics products including ceramic parts are
By hot isostatic pressing, a product that is denser and has higher strength can be obtained compared to other methods.

Conventionally, when hot isostatically forming a ceramic product with a complicated shape, a binder is mixed with the ceramic raw material, and after cold forming with a press or the like, the surface of the cold formed product 1 is coated as shown in Figure 1. The coating layer 2 was formed by applying molten glass such as silica glass or Vycor glass, and the inside of the coating layer 2 was evacuated using a degassing pipe 3, and then molded by hot static pressure method. However, with this method, there was a problem in that it was very difficult to form the coating layer 2 of molten glass on the surface of the cold-formed product 1 having a complicated shape, and it required a great deal of labor and time. It is also conceivable to form the coating layer 3 by immersing the cold-formed product 1 in molten glass.
However, in the case of the glass coating mentioned above, it is necessary to completely remove the glass coating by shot blasting etc. after hot isostatic pressing, and the dimensional accuracy of the formed and sintered product is poor, and the grinding process after sintering is required. had expended a great deal of effort.

The present invention solves the above-mentioned conventional drawbacks, and aims to provide a method for hot forming ceramic products that can form complex-shaped ceramic products in a short time.

In order to achieve the above object, the method of hot forming ceramic products of the present invention includes a cylindrical outer mold, and an upper mold and a lower mold that are slidably fitted into the outer mold. Fill the mold with ceramic powder, evacuate the inside of the mold, pour molten glass onto the outer surfaces of the upper and lower molds, seal the upper and lower molds in the outer mold with a glass layer, and heat the mold. It is configured to be placed in an isostatic pressure forming apparatus and subjected to hot isostatic press forming.

According to this configuration, there is no need to cover the ceramics with a glass coating layer after cold working, and the entire mold is placed in a hot isostatic press forming apparatus for hot isostatic press forming, resulting in high dimensional accuracy. Ceramic products can be molded easily and in a short time.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 2, 4 is a cylindrical outer mold, 5 is a middle mold, 6 is an upper mold, and 7 is a lower mold. These molds are made of high-melting point metal such as tungsten or molybdenum. O-rings 8 and 9 are attached to the circumferential surface of. Reference numerals 10 and 11 are degassing pipes passing through the upper mold 6 and lower mold 7, 12 and 13 are ceramic powders such as zircon oxide, and 14 and 15 are glass layers.

During molding, first, the middle mold 5 is fixed in the outer mold 4, and then a predetermined amount of ceramic powders 12, 13 are filled into the recesses formed by the outer mold 4 and the middle mold 5, and then the O-rings 8 and 9 are filled. The upper mold 6 and the lower mold 7 equipped with the molds are inserted into the outer mold 4, and during pressing from above and below, the air inside the molds 4 to 7 is degassed from the degassing pipes 10 and 11. Put a stopper on it and occlude it. Next, molten glass is poured into the outer surfaces of the upper mold 6 and lower mold 7 to form a glass layer 14 as shown in FIG.
After forming a mold 15 and sealing the upper mold 6 and lower mold 7 in the outer mold 4, the molds 4 to 7 are placed in a hot static pressure molding device, and a predetermined gas pressure is applied while heating them to a predetermined temperature. In addition, hot static pressure molding is performed. Two piston crowns made of ceramics are thus obtained.

In this way, there is no need for glass coating after cold working and glass removal after molding as in the prior art. Furthermore, since the process is in-mold, ceramic products with good dimensional accuracy can be easily mass-produced, and costs can be reduced through mass-production. Furthermore, there is no need for a binder to maintain the shape after cold working, making it economical. In addition, the upper mold 6 and lower mold 7 are compressed along the inner peripheral surface of the outer mold 4, so dimensional accuracy is good, and the entire outer surface of the upper mold 6 and lower mold 7 is evenly compressed by gas pressure. Therefore, there is no need to use a strong material.

In the above embodiment, an example of forming a piston crown was explained, but the present invention is not limited to this shape, but can be applied to ceramic products of various shapes, and is particularly effective when the shape of the top and bottom surfaces is complex. It is.

Furthermore, in the above embodiment, an example was explained in which two ceramic products were molded at the same time.
Of course, they may be molded one by one.

As explained above, according to the present invention, ceramic products with complicated upper and lower surfaces can be easily mass-produced, and costs can thereby be reduced. Furthermore, it is economical as it does not require a binder;
Various advantages can be obtained, such as improved dimensional accuracy and no need for strength of the mold.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of ceramics coated with molten glass according to a conventional method, and FIG. 2 is a cross-sectional view of a molded state according to a hot forming method according to an embodiment of the present invention. 4...outer mold, 6...upper mold, 7...lower mold, 12,
13...Ceramics powder, 14,15...Glass layer.

Claims (1)

[Claims] 1 Fill a mold with ceramic powder, which has a cylindrical outer mold and an upper mold and a lower mold that are slidably fitted into the outer mold, evacuate the inside of the mold, and remove the upper mold and the lower mold. Molten glass is poured into the outer surface of the mold, the upper and lower molds are sealed in the outer mold by a glass layer, and the mold is placed in a hot isostatic press molding device to perform hot isostatic press molding. A hot forming method for ceramic products.