JPS63252702A - Molding method for ceramic molded bodies - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for forming a ceramic molded body, particularly a cylindrical ceramic molded body.

Conventional technology In general, ceramics exhibit superior properties such as wear resistance, corrosion resistance, and high-temperature strength compared to metals and plastics, so they are used for pneumatic transportation of powder and granular materials such as coal, ash, coke, foundry sand, glass, and gypsum. Alternatively, it is useful for liquid transportation of granular materials such as earth and sand and blast furnace granules, and further for transportation of corrosive fluids such as corrosive gases, waste liquid slurry, and precipitated sludge.

BACKGROUND ART Conventionally, as one of the methods for molding cylindrical ceramic molded bodies such as ceramic straight pipes and curved ceramic pipes, there is a mud-smelling casting method in which mud of ceramic powder is cast into a mold. There are several methods of mud-smelling casting molding, but when molding a cylindrical ceramic molded body, the mud-draining method is generally applied. The mud removal method involves casting mud into a porous mold that has water absorption properties, such as a plaster mold.
This is a method of obtaining a cylindrical ceramic molded body having a thick wall by allowing the slurry to thicken due to water absorption in the mold over a certain period of time, and then discharging the excess slurry.

Problems to be Solved by the Invention By the way, in the above-mentioned slurry removal method, especially when manufacturing large ceramic straight pipes or ceramic curved pipes, it is difficult to make the thickness and moisture of the slurry deposited on the inner wall of the mold uniform. There was a problem that it could not be maintained and, for example, "cracking" occurred during drying.

In addition, in some cases, ceramic straight pipes and ceramic curved pipes are manufactured using cold isostatic compression molding or injection molding, but there are problems in handling the core, etc., and mold costs are high. There is a problem with this point. It is also produced by extrusion, but there are problems in that it is difficult to handle and cracks occur during drying. Furthermore, in the case of a curved pipe, there is a method in which the curved part is formed by extrusion and the straight parts at both ends are formed by straightening after extrusion, but this method still has technical problems.

As described above, in methods such as mud casting, cold isostatic compression molding, injection molding, and extrusion, there are problems such as cracking during drying and removal of the core, and it is difficult to maintain specified dimensions and quality. It takes a lot of effort to obtain the product varnish 1-
It was connected to high.

Therefore, an object of the present invention is to provide a method for molding a ceramic molded body that can solve the above problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for forming a ceramic molded body of the present invention is to form a large-diameter pipe-shaped body into which an elastic tube is fitted and a plurality of through holes are formed in the peripheral wall. In the mold,
A small-diameter pipe-shaped mold in which an elastic tube is fitted externally and multiple through holes are formed in the peripheral wall is inserted, one end between both pipe-shaped molds is closed, and then both pipe-shaped molds are closed. After putting ceramic powder or granules into the mold from the other end, the other end is closed, and then the small diameter pipe mold is closed while the through hole of the large diameter pipe mold is closed. A liquid is injected between the through-holes and the elastic tube to pre-compress the ceramic powder or granules, and then a liquid is injected through the through-holes of both pipe-shaped molds to cool the ceramic powder or granules. This is a method of molding using a hydraulic compression molding method.

Effect: According to the above-mentioned molding method, after the ceramic powder or granules are pre-compressed, the whole is molded by cold isostatic compression molding through an elastic tube, so that the ceramic powder or granules can be compressed more uniformly. There are no problems such as cracking. Furthermore, since compression is applied from the inner and outer surfaces of the cylindrical shape, a gap is created between the molds and the ceramic molded body can be easily pulled out of the mold, making it possible to easily pull out the ceramic molded body from the mold. Can be easily manufactured. Furthermore, by adjusting the pressure during pre-compression, the inner diameter of the molded tube can be changed, and the outer diameter can also be changed.

EXAMPLE Hereinafter, an example of the present invention will be explained based on FIGS. 1 to 3.

Reference numeral 1 denotes a large-diameter pipe-shaped mold (hereinafter referred to as large-diameter mold) having a plurality of through holes 2 formed in its peripheral wall, into which an elastic tube 3 made of rubber, plastic, or the like is fitted. Reference numeral 4 denotes a small-diameter pipe-shaped mold (hereinafter referred to as a small-diameter mold) which is disposed within the large-diameter mold 1 and has a plurality of through holes 5 formed in the peripheral wall, and is made of the same material as the elastic tube 3. An elastic tube 6 is fitted onto the outside. 7 and 8 are in close contact with the upper and lower ends of the small-diameter mold 4 arranged at the same central position in the large-diameter mold 1, and are connected to the central space chamber 9 inside the small-diameter mold 4 and between the two molds 1 and 4. These rain jackets 7.8 are an upper lid and a lower lid for sealing the annular space chamber 10, and are fastened and fixed by tie bolts 11. An injection hole 12 for liquid injection is formed in the upper M7, and a blind stopper 13 is provided in the through hole 2 of the large-diameter mold 1 so that it can be attached or removed with a screw or the like.

Next, a method for forming a ceramic straight pipe will be described.

First, as shown in FIG. 1, the large-diameter mold 1 is placed on the upper surface of the lower lid 8, and the small-diameter mold 4 is placed in the center of the large-diameter mold 1. Next, ceramic powder or granules A such as alumina, zirconia, silicon nitride, or silicon carbide are filled into the annular space chamber 10 between the two molds 1 and 4. After filling,
The upper cover 7 is attached under atmospheric pressure or reduced pressure, and the annular space chamber 10 is sealed by tightening the tie bolts 11.

Next, after the through hole 2 of the large-diameter mold 1 is closed with a blind stopper 13, liquid is injected under pressure into the central space chamber 9 through the injection hole 12 of the upper lid 7. Then, the liquid enters between the through hole 5 of the small diameter mold 4 and the elastic tube 6, as shown in FIG.
The ceramic powder or granules A are compressed and precompressed (for example, at a pressure of about 70 kgf/7), that is, preformed.

Note that in this state, a predetermined gap is created between the small diameter mold 4 and the elastic tube 6. Thereafter, molding is performed by cold isostatic compression molding. That is, a liquid is supplied under pressure from the through holes 2 and 5 of each of the molds 1 and 4, and the ceramic powder or granules A are uniformly pressed from the inner and outer surfaces to compression mold.

After molding, the upper and lower lids 7 and 8 may be removed and the tubular ceramic molded body taken out. This extraction can be easily performed since there are gaps between the inner and outer surfaces of the molded body and the molds 1 and 4. By changing the pressure of the pressurizing liquid during pre-compression, the inner diameter of the compact can be adjusted, and in combination with the pressure during cold isostatic compression, the outer diameter or thickness of the compact can be adjusted. is also adjustable.

By the way, in the above embodiment, the manufacturing of straight pipes has been described, but of course it can also be applied to manufacturing curved pipes. In addition, during molding, after filling the annular space chamber with ceramic powder or granules, the through hole of the large-diameter mold was closed with a blind plug. It's okay.

Effects of the Invention According to the method for molding a ceramic molded body of the present invention, the ceramic powder or granules are pre-compressed and then molded as a whole by cold isostatic compression molding through an elastic tube. The granules can be compression molded more uniformly, and problems such as cracking do not occur.

In addition, since compression is applied from the inner and outer surfaces of the cylindrical shape, a gap is created between the molds and the ceramic molded body can be easily extracted from the mold. It can be easily manufactured and leads to cost reduction. Furthermore, by adjusting the pressure during pre-compression, the inner diameter of the molded tube can be changed, and the outer diameter can also be changed.

[Brief explanation of drawings]

1 to 3 are cross-sectional views for explaining a molding method according to an embodiment of the present invention. 1...Large diameter pipe-shaped mold, 2...Through hole, 3...
Elastic tube, 4...Small diameter pipe-shaped mold, 5...Through hole, 6...Elastic tube, 7...Top lid, 8...
Lower lid, 10... Annular space chamber, 12... Injection hole, 13
...Blind plug.

Claims (1)

[Claims] 1. A large diameter pipe-shaped mold into which an elastic tube is fitted inside and a plurality of through holes formed in the peripheral wall, and a small diameter pipe into which an elastic tube is fitted externally and a plurality of through holes are formed in the peripheral wall. Insert the pipe-shaped mold, then close one end between both pipe-shaped molds, then put ceramic powder or granules inside from the other end between both pipe-shaped molds, and then close the other end. The ends are closed, and then, with the through-hole of the large-diameter pipe-like mold closed, a liquid is injected between the through-hole of the small-diameter pipe-like mold and the elastic tube to form ceramic powder or granules. 1. A method for forming a ceramic molded body, which comprises pre-compressing a ceramic powder or granules using a cold isostatic compression molding method by injecting a liquid through the through-holes of both pipe-shaped molds.