JPH079071A - Molding material for casting mold and casting mold consisting of this molding material - Google Patents

Abstract

PURPOSE:To cause the deliquescence of the casting mold itself by merely resting the casting mold in the atm. air or water without executing shake-out to be executed in order to obtain an as-cast product after casting by applying impart thereto from the outside in a casting operation. CONSTITUTION:The molding material of the casting mold is constituted by agitating and mixing at last a binder and fine powder and powder and granular material of inorg. salts having a deliquescent property at required ratios. More preferably, silica sand is agitated and mixed with the molding material and the binder is the fine powder and powder and granular material of a phenolic resin and the inorg. salts having the deliquescent property are anhydrious calcium chloride.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is a mold (outer mold / core mold).
Regarding the molding material of the above, in detail, when demolding to obtain an as-cast product after casting, simply leave the mold (outer mold / core mold) in the air or water, and the deliquescent effect of the mold itself The present invention relates to a molding material for a mold that can be released from the mold.

[0002]

2. Description of the Related Art Casting is performed by melting a metal material by heating to form hot water, and then pouring the hot water into a mold called an outer mold or a core mold, which is made of molding sand, and is cooled and solidified. It is a method of manufacturing a machine tool, which can easily cast not only the one having a complicated surface shape but also a machine part having a complicated internal structure.

Therefore, the molding sand as the molding material for the mold (outer mold / core mold) has excellent bonding strength and has a coagulating property such that the mold can withstand the pressure of hot water. Appropriate size and shape, with a granularity that allows you to perfectly copy the original shape to the details of the mold and clean the skin, has excellent breathability and can easily release water vapor, gas, etc. The mold must be able to deform to some extent in response to the shrinkage of the casting metal, and must be plastic enough to avoid cracks in the casting. It is said to be preferable to satisfy various requirements such as having heat resistance so as not to cause skin burn and the like.

From the above viewpoints, therefore, as casting sand, (a) silica sand mixed with clay such as bentonite and refractory clay as a binder, (b) silica sand,
A mixture of starches such as wheat flour and corn flour,
(C) Silica sand mixed with oils such as linseed oil and fish oil, (d) Silica sand mixed with sugars such as ozin oil (papermaking pulp waste liquid), (e) Silica What mixed fine powder of carboxylic acid resin (phenol resin) in sand,
(F) A mixture of silica sand and a room temperature curable furan resin or phenol resin, which is kneaded with each curing agent, is selected and used in accordance with various molding methods.

[0005]

However, in the case of the conventional foundry sand, the unmolding for obtaining the as-cast product after the casting operation is performed by heating after removing the adhesive force of the phenol resin or the like, and then by hand. Since it is done by giving an external impact by work, or by giving an external impact by a machine called a shakeout machine,
It took time and effort to get out of shape. In addition, since noise and dust generated when the mold is removed scatters and diffuses and pollutes the air in the factory, it is not preferable for environmental hygiene, and it is necessary to secure personnel who are engaged in this type of work. The actual situation is that there is a problem. The present invention, in view of the above situation, was devised to eliminate the conventional drawbacks, as the molding material of the mold, the mold has excellent bonding strength and can withstand the pressure of hot water, Although it has good breathability and can copy the details of the original shape completely to make a mold with high dimensional accuracy, when unmolding to obtain an as-cast product after casting, simply remove the mold from the atmosphere. Alternatively, the mold can be released by simply decanting it by the deliquescent action of the mold itself, which saves labor for the mold releasing work and allows the mold releasing work to be performed without damaging the environmental hygiene in the factory. The purpose is to provide the material.

[0006]

In order to solve the above-mentioned problems, the molding material of the mold adopted by the present invention comprises at least a binder and a fine powder or granules of a deliquescent inorganic salt in a required ratio. It is characterized in that it is used when a casting having an arbitrary shape is formed by mixing with stirring and blowing it into a heated die (for outer die / core die). It is preferable to employ a fine powder or a granular material of a phenol resin as the binder. It is preferable to stir and mix silica sand at a required ratio in the molding material, but fine powder or granules of ceramics may be stirred and mixed instead of silica sand. Anhydrous calcium chloride is preferably used as the deliquescent inorganic salt. Further, it is preferable that the mold is provided with a moisture-proof means so as to prevent the mold made of a molding material containing a deliquescent inorganic salt from absorbing water in the atmosphere and self-destructing before casting.

[0007]

For example, the molding material of the mold, which is obtained by stirring and mixing silica gel sand with the phenol resin granules and the deliquescent inorganic salt granules at the required ratio, When it is blown into molds and core molds, the granular particles of phenolic resin mixed in the molding material act as a binder, and the inorganic particles have deliquescent properties between particles of silica sand and particles of silica sand. The salt granules are adhered to each other and the molding material is solidified to mold a mold (outer mold / core mold) with high dimensional accuracy. Then, since the molding material is mixed with granular particles of a deliquescent inorganic salt, after casting, if the mold is left in the air or water, the deliquescent inorganic salt absorbs water. The mold self-destroys by liquefying.
Therefore, it is not necessary to hit the mold (outer mold / core mold) from the outside to break the mold, and the mold can be unmolded simply by leaving it in the air or water.

[0008]

EXAMPLES Examples of the present invention will be described in detail below. The molding material of the mold is formed by stirring and mixing at least a binder and a fine powder or granules of a deliquescent inorganic salt with a required ratio, and silica sand is stirred and mixed at a required ratio. Is preferred. Further, preferably, the binder is a fine powder or granules of phenolic resin, and the deliquescent inorganic salt is anhydrous calcium chloride.

The molding material of the mold is, for example, silica sand 100.
On the other hand, 1.5 to 2.5% by weight of fine powder or granules of phenol resin, 5 to 25% of fine powder or granules of anhydrous calcium chloride as an inorganic salt having deliquescent property.
It is formed by stirring and mixing in a weight percentage. However, quartz sand,
The mixing ratio of phenol resin and anhydrous calcium chloride is
It is not limited to this, and the duration of the template can be controlled by the ratio of anhydrous calcium chloride which is an inorganic salt having a deliquescent property, which is appropriately selected depending on the type and shape of the core. Further, as a result of the experiment, it was found that it is also possible to mold the mold with a molding material obtained by stirring and mixing only anhydrous calcium chloride and phenol resin. In this case, since anhydrous calcium chloride has a smaller specific gravity than silica sand, it goes without saying that it is necessary to increase the weight ratio of the phenol resin in the whole.

In this embodiment, anhydrous calcium chloride was selected as the deliquescent inorganic salt, but it is not limited to this and any other salt may be used as long as it can withstand the heat during molding of the mold. Further, instead of silica sand, fine powder or granules of ceramics may be mixed by stirring. As the binder, a known material other than the phenol resin can be used, but a material that generates less gas during heating is preferable. In addition, when a processed product of sodium carbonate and bentonite was added to the molding material at a required ratio, a mold with better performance could be obtained. The bentonite processed product referred to here is a product obtained by heat-treating bentonite into particles, and it was found that the deliquescent property is improved by adding the bentonite processed product.

Next, in order to form a mold (outer mold / core mold) using the molding material of the above mold, a molding machine is used.
Moulding machine and core sand blowing machine (coreblowin
g machine) and so on. For example, when molding a molding material into a metal core box to form a core, the core sand blower is used to blow the molding material out of the tank with the force of compressed air. All you have to do is mold it into the child box. When the heating temperature of the core box becomes 200 ° C. or higher (preferably about 280 ° C.), the fine powder or powdery substance of the phenol resin is formed between the particles of silica sand and the particles of silica sand and anhydrous calcium chloride. Since the fine powder or granules are adhered to each other to solidify the molding material, a core with high dimensional accuracy can be produced. Then, the core is taken out from the core box to a drying stand made of metal and dried to obtain a core in a strong dry state. In this case, even if the heating temperature of the core box is 200 ° C. or higher to solidify the molding material, the melting point of calcium chloride is 774 ° C., so that the deliquescent property of calcium chloride does not change at all. In addition, in the above-mentioned embodiment, the case of making the core mold by using the core sand blowing machine has been described, but the present invention is not limited to this, and a molding machine or a fully automatic molding machine is used. It goes without saying that these molding materials can be used even when the outer mold is made by using the above method.

[0012] In order to obtain an as-cast product after the casting operation, the mold has to be released from the mold, but the mold-forming material according to the present invention contains decalcified anhydrous calcium chloride fine powder or granules. Since there is no need to hit the mold (outer mold / core mold) from the outside as in the conventional case to break it, the mold can be released by simply leaving the mold in the air or water. Therefore, when removing the mold,
Not only does heat treatment become unnecessary, but air pollution due to noise and dust generation is reduced, and the work environment hygiene in the factory is improved. That is, when the template (outer mold / core mold) is left in water, the anhydrous calcium chloride crystals immediately absorb water and dissolve in water, which promotes self-disintegration of the template.
According to the experiment, when left in stationary water, the small ones can be unmolded in about 2 hours, and the large ones can be released in about 5 hours. When left in running water, self-disintegration is further promoted. It was confirmed to be done. Also, when the template is left in the atmosphere, the anhydrous calcium chloride crystals absorb water in the atmosphere and then dissolve in water, so the self-degradation of the template is slower than in the case of being left in water, and it takes about 2 days. I got out of shape. However, it is also possible to increase the rate of template self-disintegration by increasing the ratio of anhydrous calcium chloride, and it is needless to say that the humidity affects the rate of self-disintegration when left in the atmosphere. Yes. Incidentally, since the mold absorbs water, the mold made of the mold material according to the present application is suitable for casting of non-ferrous metals such as aluminum alloys, but by mixing an appropriate amount of sodium carbonate into the mold-forming material, a casting in the case of cast iron It is also possible to prevent the occurrence of rust on the surface.

Further, since the mold is generally transported to another factory or the like after molding and used for casting, it is possible that the mold absorbs moisture and self-destroys between the molding and the time of casting. Must be avoided. Therefore, it is preferable that the mold made of the molding material according to the present application is provided with the moisture-proof means. As the moisture-proof means, it is necessary to shut off the mold from the outside air, and for example, sealing the mold in a vacuum state with a vinyl bag, a plastic bag or the like can be mentioned. Further, as another moisture-proof means, it is possible to apply or impregnate the surface of the mold with a water-repellent material. Examples of the water-repellent material include silicone oil and fluorine-based resin. After cooling the molded mold, the surface thereof is coated with silicone oil or the like. During casting, since the silicone oil and the like are vaporized by the high temperature of the hot water, the coating of the silicone oil and the like does not affect the self-destruction of the mold after the casting operation. In addition, it is preferable that the water-repellent material generate less gas by heating.

[0014]

In summary, according to the present invention, a binder and a fine powder or granules of a deliquescent inorganic salt are stirred and mixed at a required ratio, and a heated mold (for outer mold. Mold (outer mold / core mold) because it is used when molding a casting of any shape by blowing it into the core mold).
As a molding material of, the mold has excellent bonding strength, can withstand the pressure of hot water, has good air permeability, and it is possible to make a mold with high dimensional accuracy by completely copying the details of the original shape. When removing the mold to obtain an as-cast product after the casting operation, simply leaving the mold in the air or water allows the mold to be released by the deliquescent action of the mold itself, thus impairing the working environment hygiene in the factory. The present invention has a very useful new effect that allows the unmolding work to be performed without any need. In particular, the molding material of the mold according to the present invention is preferably used for the core, and even if the core has a complicated shape, the mold can be easily released.

 ─────────────────────────────────────────────────── ─── Continuation of front page (71) Applicant 593098277 Kenji Koizumi 1-1754 Tomonmae, Omiya-shi, Saitama Prefecture (1) (72) Inventor Hiroshi Ohira 1-28-4 Seta, Setagaya-ku, Tokyo (72) Inventor Hirotake Onoue 2397-50 Nakano, Ura-cho, Euraku-gun, Gunma Inventor Hideo Nagashima 688-7 Maruyama-cho, Ashikaga City, Tochigi Prefecture (72) Inventor Yutaka Nagashima 688-7 Maruyama-cho, Ashikaga City, Tochigi Prefecture Kenji Koizumi Saitama 1-1754 Tomonmae, Omiya, Omiya-shi, Japan

Claims (7)

[Claims] 1. A binder and a fine powder or granules of a deliquescent inorganic salt are mixed by stirring at a required ratio, and the mixture is filled in a mold (for an outer mold or a core mold) to be optional. A molding material for a mold, which is used when molding a casting in the shape of. 2. The molding material for a mold according to claim 1, wherein silica sand is stirred and mixed in the molding material. 3. The molding material for a mold according to claim 1, wherein the binder is a fine powder or granules of a phenol resin. 4. The mold forming material according to claim 1, wherein the deliquescent inorganic salt is anhydrous calcium chloride. 5. A mold molded from the molding material according to any one of claims 1 to 4. 6. The mold according to claim 5, further comprising a moisture-proof means. 7. The mold according to claim 6, wherein the surface of the mold is coated or impregnated with a water-repellent material.