JPS61189905A - Mold for slip casting - 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 Application of the Invention] The present invention is directed to a mold for slip casting, in which a molded product is made by casting a slip of particles such as ceramic grains, metal grains, carbon grains, etc. In particular, the present invention relates to a mold fJJ/ which is particularly suitable for producing molded products having complex shapes and thin-walled parts.

[Background of the invention]

In slip casting molding, the gap between the molds is narrow in thin-walled parts of the molded product, and therefore slip flow is poor. If the mold is water-absorbent (for example, a plaster mold), the fluidity of the slip in thin-walled areas will decrease as the slip absorbs moisture, and the slip may solidify before reaching the innermost part of the mold. As a countermeasure for this,
For example, there is a method of using a non-water-absorbing resin mold for the thin wall part as disclosed in JP-A-52-153690.
It is difficult to select a solvent for removal, and it takes a long time to melt and remove.

[Purpose of the invention]

In view of the above, it is an object of the present invention to provide a slip casting mold that controls the water absorption of the thin wall portion and is suitable for molding products with complex shapes.

[Summary of the invention]

The present invention provides a mold in which a slip is cast into the mold and am removed after solidification of the slip, in which the mold is molded with a water-bathable binder, and a non-water-absorbing film is formed on all or part of the surface of the mold. It is characterized by this.

That is, a solution of aggregate and a water-soluble binder is kneaded, compacted in a mold (for example, a wooden mold), and then a non-water-absorbing film is formed on all or part of the surface of the dried mold. .

The dried mold has the strength necessary for assembly, and since its surface is covered with a non-water-absorbing film, it has the same function as a core made of resin or the like. The core made by this method is combined with the @ mold, and the space is filled with ceramic slip.

After solidification, the shell is removed by adding water. That is, since the binding force of the water-soluble binder is reduced by the added water, it is possible to remove the water-soluble binder together with the non-water-absorbing film without applying unnecessary force to the molded article.

The present invention is characterized in that the solvent is water, and a non-water-absorbing film is not applied to areas where water-absorbing properties are desired.

For example, particles of alumina (At2031, magnesia (MgOl), zircon sand, silica sand, etc. are used as the mold aggregate, and sodium carbonate (Na2) is used as the water-soluble binder.
COsl r Carbonates such as potassium carbonate A (K2 C03), chloride) IJum (Na(,t), potassium chloride (KC2I), magnesium chloride (MgCtzl.

Lithium chloride (LicL) Z Any chloride, trisodium phosphate A (N a3P 041
3P04).

Phosphates such as dipotassium hydrogen phosphate (K2HPO4), magnesium sulfate (Mg804), sodium sulfate (Na
Sulfates such as zSO41, (#C potassium acid (K2SO41), ammonium sulfate ((NH412S 041) are used.

The mixing ratio of aggregate, binder and water is preferably 50-95% by weight for aggregate and 5-50% by weight for binder and water in terms of mold strength and economy.

The greater the amount of binder added, the more stable the mold strength becomes, the more stable the surface of the mold becomes, and the easier the handling becomes.

However, in the present invention, which aims to reduce the mold strength due to water absorption from the slip, an unnecessarily high strength is not desired. If the binder is added in excess, the surface of the mold will be roughened during drying, so it is not preferable to add more than 47% by weight. Further, if the amount of binder is less than double f%, the mold strength will be insufficient and it is not practical.

On the other hand, the amount of water added affects the workability during mold creation and the stability of the mold surface. In particular, when the water content is less than 3% of the total weight including aggregate, it becomes difficult to create a mold.

Therefore, the sum of binder and water is 5 to 50'ii based on the total weight.
Regret is appropriate.

The coating material formed on the surface of the mold preferably has a non-water absorption function. It will not work if the surface of the mold is coated or impregnated with oil-based materials such as silicone oil or petrolatum. In addition, if a film is formed by spraying a rubber or plastic film on the surface of the mold, water can be poured into the mold at the time of release, reducing the strength of the mold, and then removing the film, including the film. The surface of the molded product is also cleaner, making it more effective. There are silicone rubber and urethane sealant rubber that form such a film.
It is not limited to these.

[Embodiments of the invention]

Examples of the present invention will be described below.

[Embodiment 1] Fig. 1 is an external view of a wheel molded by the mold of the present invention, and is composed of a boss 11, a cylinder 2, and a rib 3, and the rib 3 is particularly thin. FIG. 2 shows a cross section of a mold for molding this wheel. The main molds 4a and 4b are plaster molds and have water absorption properties. Core 5 is made of plaster mold, core 5a.

5b, 6c, and 6d are water-soluble templates. Cores 6a and 6b
, 6b and 6c, 6c and 6d, and 6d and 6a facing each other were coated with a non-water-absorbing film 7.

The skin 1x7 is made of one-component silicone rubber with a thickness of 0.1 wm formed on the surface, one with a urethane sealant rubber formed on the surface of 0.1 cm, one with silicone oil impregnated on the surface, and petroleum jelly. Each sample was prepared with a film formed on its surface. In addition, the cores 6a, 6b, 6
c, 6d aggregate is alumina powder, alumina powder, 10
To 0 parts by weight, 16 parts by weight of a solution in which 105 parts by weight of potassium carbonate as a binder was dissolved in 100 parts by weight of water was added.

The above @-type combination and alumina slip (15 parts by weight of water were added to 100 parts by weight of Z4 μm particles and stirred for 6 hours) were poured into the flask. Cores 6a and 6b, 6b and 5c
, 5c and 6d, and 6d and 6a were coated with the non-water-absorbing film 7, so the fluidity of the slip was extremely good.

After pouring the slip, it was confirmed that each part was completely solidified in one hour, and the main molds 4a, 4b and core 5 were released.

In addition, the cores 6a, 6b, 6c, and 6d absorbed moisture and disintegrated easily, so that they could be easily removed together with the coating 7.

[Example 2] In the mold combination of Example 1, cores 6a, 6b, 6c, and 6d were prepared as shown in the following table, with A, B, and C, respectively.
, D were created.

(Parts by weight) Cores 5a, 5b, 6c, 6d (a film 7t of silicone rubber was formed on the entire surface of the D side), and after the rubber had hardened, the same alumina slip as in Example 1 was poured in. After the slip had solidified,
Main mold L1 core 5 is released, cores 6a, 6b, 6c, 6d
The silicone rubber film 7, which had been softened and removed by injecting water from above, was also removed.

The A-type part made of any composition could be easily released from the mold, and the wheel surface was clean. In addition, with this method, no excessive force was applied to the wheel during demolding, so there was no occurrence of cracks in the thin wall portion (rim).

〔Effect of the invention〕

As explained above, according to the present invention, by using a slip casting mold in which a mold is made from a water-soluble binder and a non-water-absorbing film is applied to all or part of the surface of the mold, thin-walled In addition to controlling the water absorption capacity of the parts, after the slip has solidified, the disintegrated cast and film can be easily removed by adding water to the water-soluble cast iron or absorbing the water in the slip, so thin-walled parts can be easily removed. Cracking can be prevented even in molded products that have complex shapes or require a core.

[Brief explanation of the drawing]

FIG. 1 is an external view of a molded product molded by the mold of the present invention, and FIG. 2 is an explanatory diagram showing the state of assembly of the mold of the present invention. 4a, 4b...-main mold, 5...core, 6a, 6b, 6
c.

Claims (1)

[Scope of Claims] 1. In a mold in which a slip is cast into the mold and the mold is removed after the slip has solidified, the mold is molded with a water-soluble binder and a non-water-absorbing film is formed on its surface. A slip casting mold featuring: 2. Claim 1, characterized in that the mold aggregate is alumina, magnesia, zircon sand, or silica sand particles.
Mold for slip casting as described in section. 3. The mold for slip casting according to claim 1, wherein the binder is carbonate. 4. The mold for slip casting according to claim 3, wherein the carbonate is sodium carbonate or potassium carbonate. 5. The slip casting mold according to claim 1, wherein the binder is a chloride. 6. The slip casting mold according to claim 5, wherein the chloride is sodium chloride, potassium chloride, magnesium chloride, or lithium chloride. 7. The slip casting mold according to claim 1, wherein the binder is a phosphate. 8. The slip casting mold according to claim 7, wherein the phosphate is trisodium phosphate, tripotassium phosphate, or dipotassium hydrogen phosphate. 9. The mold for slip casting according to claim 1, wherein the binder is a sulfate. 10. The slip casting mold according to claim 9, wherein the sulfate is magnesium sulfate, potassium sulfate, sodium sulfate, aluminum sulfate, or ammonium sulfate. 11. The slip casting mold according to any one of claims 3, 5, 7, and 9, characterized in that alcohol is added to the binder. 12. The slip casting mold according to claim 1, wherein the mold is provided with a cavity. 13. Aggregate; 50-95% by weight, binder and water; 5-50
The slip casting mold according to claim 1, characterized in that the amount is expressed as % by weight. 14. The slip casting mold according to claim 1, wherein the non-water-absorbing film is a urethane sealant rubber, a room-temperature curing silicone rubber, or an oxime-free one-component silicone rubber. 15. The slip casting mold according to claim 1, wherein the non-water-absorbing film is an oil-based paint. 16. The slip casting mold according to claim 15, wherein the oil-based paint is silicone oil or vaseline. 17. The slip casting mold according to claim 1, wherein the non-water-absorbing film is a vinyl resin paint.