JPS6061136A - Casting mold for slip casting - Google Patents

Abstract

PURPOSE:To improve initial strength of a casting mold for slip casting and a collapsing property after heating and to permit easy removal of an intricate core by incorporating specific pts. wt. of glue into a gypsum mold added with a vegetable material such as cellulose or the like. CONSTITUTION:Glue is incorporated at a ratio, by weight %, of 100 gypsum, 2-20 cellulose and 0.2-1.0 glue into a gypsum mold added with a vegetable material such as cellulose having water absorptivity and water insolubility or the like. The initial strength of the mold is improved by the glue added thereto and if the slip-formed article and core are heated after casting, the binding force of the mold decreases and the easy removal of the core having an intricate shape is made possible.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a slip casing for obtaining a molded body by casting slip containing refractory powder such as ceramic powder, metal powder, carbon powder, etc. The present invention relates to a slip casting mold suitable for molds for stains, and particularly for molding molded objects that require a core with a shape that cannot be removed due to a reverse slope.

[Background of the invention]

When using slip casting to mold a hollow molded body with a complicated cavity shape, that is, a molded body that requires a core with a complicated shape that cannot be removed due to a reverse gradient, it is difficult to remove the core using conventional plaster molds. Or it was impossible.

Therefore, the applicant of the present application has added a vegetable material such as flaky cellulose (vegetable fiber) in the range of 2 to 20 to the plaster mold, and by a slight heating operation, the disintegration of one mold, especially the core, has been significantly improved. We have developed a mold that improves the performance of the invention, and have filed a patent application in Japanese Patent Application No. 58-65372 prior to filing this application. However, in the technology related to that earlier application, the rate of decrease in the initial strength of the mold is somewhat large due to the addition of cellulose, and the disintegration of the mold after heating operation is not perfect, so it is even more difficult to apply. Improvement was desired.

[Purpose of the invention]

The present invention was made to solve the above-mentioned problems, and it increases the initial strength of the mold and significantly improves the mold disintegration property after heating operation, so that it can be used for cores of any complex shape. The object of the present invention is to provide a slip casting mold that is easy to remove.

[Summary of the invention]

The structure of the slip casting mold according to the present invention is that the slip casting mold is made of a gypsum mold to which a vegetable substance is added, and the gypsum mold contains glue.

As an additional note, the slip casting mold of the present invention is a gypsum mold containing flaky cellulose, which is used to cast and shape a slip containing ceramic powder, etc., in which a small amount of glue is added to the gypsum mold. It is something.

Next, the concept behind the present invention will be described.

The reason why a small amount of glue is added to a plaster mold containing vegetable substances such as cellulose is due to the addition of glue.
This is to increase the initial strength of the mold and to significantly improve the collapsibility of the mold after heating operation.

It is more preferable that the vegetable substance contained has water-absorbing properties as well as water-insoluble properties.

In the present invention, a preferred water-absorbing plant material is, for example, cellulose (vegetable fiber), and it is desirable to use cellulose in the form of short pieces. The reason for this is that the molding material has better fluidity when it is shaped into pieces. Papers made from cellulose may also be used. In this case, for example, thin paper is preferred from the viewpoint of water absorption and water insolubility, and is used after being made into pieces and uniformly dispersed in the gypsum slurry.

The reason why vegetable matter and glue are included in the plaster mold is that the addition of glue increases the initial strength of the fishing mold, and the slip molded product after casting is heated together with the core to burn off the vegetable matter and glue. This is to cause the mold to lose its cohesive strength and reduce the initial strength of the mold to near zero.

Furthermore, if the plant material is water-soluble, the plant material will be filled between the gypsum particles and water absorption will be significantly reduced, so it is preferably water-insoluble.

The reason why the gypsum mold contains a water-absorbing vegetable substance is to increase the water absorption effect of the mold from the slip and shorten the solidification time of the slip.

Glue is added in an amount of 0.2 to 1.0% to a plaster mold containing 100 parts by weight of plaster and 2 to 20 parts by weight of cellulose.
Preferably, it is 0 parts by weight.

If the amount added is less than 0.05 parts by weight, the effect of adding glue will hardly appear, that is, the initial strength of the mold will be 4 kg/
Since it remains small at less than crA, it is easily damaged during slip casting and difficult to handle, and the residual compressive strength after heating (hereinafter referred to as "residual strength") is somewhat large, making removal of the mold difficult. It is.

Furthermore, if the amount of glue added is 2,00 parts by weight or more, the hardening time of the gypsum mold will be significantly delayed due to the glue, making it impossible to put it into practical use.

Therefore, the appropriate amount of glue to be added is 0.05 to 2.00 parts by weight per 100 parts by weight of gypsum.

In order to obtain the mold of the present invention, the process from loading the slip to firing the molded body is as follows: casting the slip → disappearance of vegetable matter and glue in the mold (core) by heating → collapse and removal of the mold → This is carried out in the order of firing the molded bodies.

The mold after molding becomes sufficiently dry by heating at 80C for about 4 hours, and is in a state suitable for absorbing moisture in the slip. Since glue is added, it has sufficient initial strength compared to the case without the addition.

The heating temperature for burning off the vegetable matter and glue may be around 500C, and the plaster mold will not lose its cohesive strength due to the burning off of the vegetable matter and glue.
Easily disintegrated by external forces below crA.

Therefore, the external force is preferably, for example, extremely weak compressed air or vacuum suction, which allows disintegration and removal to be performed at the same time.

An unfired molded body (semi-finished product) is produced by removing the plaster mold (core), and a complete molded body, such as ceramic or metal, is obtained by subsequent firing.

[Embodiments of the invention]

This will be explained below using specific examples.

(Example 1) Cellulose flakes, glue, and water were added to gypsum in the proportions shown in Table 1, and kneaded at 200 rP for 5 minutes.

(*) 901 pieces of 100mesh were mixed and the resulting mold slurry was poured into a wooden mold to create a diameter of φ50.
Create a test piece of XH50 and heat it in a Matsufuru furnace at 80-800C.
The mixture was heated for 60 minutes at a temperature of . After heating, the test piece was taken out and its residual strength was measured after it was left to cool in the air. The results are shown in FIG.

FIG. 1 is a diagram showing the relationship between heating temperature and residual strength of an embodiment of the present invention and a conventional slip casting mold. Compressive strength (Kg/ctd) is taken. Curve 1 in the diagram
Curve 2 is the one with no glue added, and curve 2 is the one with 0.2 parts by weight of glue added.

As is clear from the figure, when glue is added, the initial strength (strength after heating at 80CX for 4 hours) increases by 20%, although the wet strength is exactly the same. On the other hand, 400C
The residual strength after heating is lower than that without additives. Taking 400C as an example, the residual strength when no glue is added is IQ/cIIi, but when 0.2 parts by weight of glue is added, the residual strength is 0.2Kii/c.
IIi, which is actually a value of 115.

Therefore, it can be seen that the addition of glue makes it much easier to disintegrate and remove the core for slip casting than when no glue is added.

(Example 2) Cellulose flakes, glue, and water were added to gypsum in the proportions shown in Table 2, and kneaded at 20orpl for 5 minutes.

(II): 10Q megh passed 90 rQ) A test piece was prepared in the same manner as in Example 1, and 60% at 500C.
After heating for a minute, the specimen was allowed to cool inside the wall, and the residual strength of each specimen was measured. The results are shown in song +11j11 in Figure 2.

FIG. 2 is a diagram showing the relationship between the amount of glue added and residual strength and initial strength in a slip casting mold according to an embodiment of the present invention. The horizontal axis shows the amount of glue added (CH), and the vertical axis shows the residual compressive strength (Kl/crA).
and initial strength (K9/Cf/l).

As is clear from the figure, when the amount of glue added is 0.2 or more, the residual strength becomes 115 or less compared to the case where no glue is added.

(Example 3) Test pieces were prepared in the same manner as in Example 2, and the initial strength (compressive strength after heating at 80CX for 4 hours) was measured for each test piece, and the results are shown in curve 2 in FIG.

As is clear from Figure 2, the amount of glue added is 1.0-
If it is above, the initial strength of the mold will be about 3.7 to /(10) crl or less.

Therefore, it is easily damaged during slip casting and becomes difficult to handle.

As is clear from these examples, when both residual strength and initial strength are taken into account, the amount of glue added is 0.2~
1.0 parts by weight is desirable.

In addition, in these Examples, since the vegetable VlJ material and glue are possessed, the initial strength of the mold is improved, and by heating after slip casting, the mold strength can be significantly reduced.

For this reason, there is an effect that hollow molded bodies that require a core of a temporary shape that cannot be removed due to a reverse gradient can be produced extremely easily.

In addition, if the slip casting mold of this example is applied to the main mold, there is no need to divide the main mold, so it is possible to make a highly accurate molded body, and the water absorption of the plaster mold is also improved. Therefore, there are additional effects such as shortening the slip assimilation time.

(11) [Effects of the Invention] As described above, according to the present invention, the initial strength of the mold is increased, the collapsibility of the mold after heating operation is significantly improved, and a core of any complicated shape can be used. Even if there is a slip casting mold, it is possible to provide a slip casting mold that is easy to remove.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between heating temperature and residual strength of slip casting molds according to an embodiment of the present invention and a conventional slip casting mold, and FIG.
It is a diagram showing the relationship between the amount of glue added and residual strength and initial strength in a casting mold. (12) Kaya 20 Glue Fuka amount (Y)

Claims (1)

[Claims] 1. A slip plate made of a plaster mold to which vegetable matter has been added.
1. A slip casting mold for a casting bowl, characterized in that the plaster mold contains glue. 2. The slip casting mold according to claim 1, which is made of a water-absorbing plant material. 3. The mold for slip casting according to claim 1, which is made of a water-insoluble vegetable material. 4. The mold for slip casting according to claim 1, wherein the vegetable material is cellulose. 5. Gypsum: 100 parts by weight, cellulose = 2-20
The leg mold for slip casting according to claim 4, which contains 0.2 to 1.0 parts by weight of glue. 6. The mold for slip casting according to claim 1, which is made of vegetable material as paper flakes.