JPH09174194A - Manufacture of mold and method for distingrating mold obtained by this method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply obtain a mold having desired strength by adding a specific quantity of water glass into molding sand, kneading and executing a forming and drying treatments to a mold. SOLUTION: The mold sand is used to the one having e.g. No.5-8 particle size distribution (48-150 mesh) and about 77% SiO2 content. The adding quantity of the water glass is made to 1-4wt.% to the molding sand. After forming the mold by using the molding sand adding the water glass and kneaded, the drying treatment is executed. The drying treatment is executed by blowing the air from one side of a metallic mold filling up the molding sand and sucking from the other part. The drying uses warm blasting at 80-120 deg.C. The mold is made to a core. The mold obtd. with the drying treatment is dipped into water and disintegrated. By this method, the drying time can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mold such as a core, and a method for disintegrating the mold obtained by the method, and in particular, a mold can be easily manufactured and a casting product is cast after casting. The present invention relates to the one that enables easy separation of sand.

[0002]

2. Description of the Related Art Conventionally, for example, phenol resin or water glass has been used as a binder used when molding a core. Among them, the method of using a phenol resin as a binder is known as a shell mold method, and this is kneaded into molding sand by using a phenol resin as a binder and hexamethylenetetramine as a hardening agent to form mold sand. After being manufactured, it is filled in a preheated mold and then fired to mold a mold such as a core.

When water glass is used as a binder, 4 to 6% (weight%, the same applies hereinafter) of water glass is added and kneaded to foundry sand, and the mixture is filled in a mold and then treated with CO2 gas. Then, a mold such as a core is molded.

[0004]

However, the template obtained by the former shell mold method of the above-mentioned conventional method has a problem that the disintegration property is inferior. Of the so-called resin sand, which is coated with a binder during casting, the phenol resin on the surface side of the mold that is in contact with the molten metal is thermally decomposed, but the resin sand remains inside and the strength (hardness) is increased. This is because some of them are kept).

Further, the mold obtained by using the latter water glass of the above-mentioned conventional method has a drawback in that a desired mold strength can be obtained by CO2 gas treatment, but in order to obtain the strength, the treatment time becomes long.

In order to solve the above problems, it may be possible to reduce the strength of the mold from the beginning to manufacture a mold having good disintegration property. It was not possible to maintain the strength of the mold in the above, and there was a high possibility that the casting product would become defective, and the mold strength could not be reduced from the beginning.

Therefore, the present invention has been made to solve the above-mentioned drawbacks, and an object thereof is to easily manufacture a mold that maintains a predetermined strength that does not collapse during casting, and easily collapses after casting. The present invention relates to a mold disintegration method.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the method for producing a mold according to the present invention comprises adding 1 to 4% of water glass to a molding sand and kneading the mixture, and molding a mold using the mixture.
It is characterized in that it is dried to produce a mold. Further, the above-mentioned drying is characterized by being performed with warm air of 80 to 120 ° C. The mold is a core.

In order to achieve the above-mentioned object, the method of disintegrating a mold according to the present invention is obtained by adding 1 to 4% of water glass to a molding sand, kneading the mixture, molding the mold using this, and then subjecting it to a drying treatment. It is characterized in that the obtained mold is immersed in water and collapsed. The temperature of the water is 50 ° C. or higher. The mold is a core.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The foundry sand used in the present invention is a known foundry sand, for example, having a particle size distribution of 5 to 8 (48 to 150 mesh) and Sio2 of about 77%.

The addition amount of water glass is 1% or more with respect to foundry sand. When the amount of water glass added is less than 1%, the strength required as a mold cannot be obtained.

When the amount of water glass added is about 1.5%, sufficient strength as a mold can be obtained. If the amount exceeds 4%, excess water glass is used, which is uneconomical.

The water-glass-added and kneaded mold sand is well-known for blowing, jolt squeeze, or handing into a mold of a mold, for example, a mold made of Al or FC for core production, which is configured to be passable. It is filled by the method of and is transferred to the next drying process.

The drying treatment can be carried out by blowing air from one of the molds filled with foundry sand and sucking air from the other. The air used is preferably dry air in order to accelerate the drying process, and particularly when hot air of 80 to 120 ° C. is used, it can be economically performed without requiring a particularly large heating means.

The drying time is not uniform depending on the size of the mold, but it is carried out until the water content of the water glass contained in the molding sand is removed and the molding sand is adhered to each other to increase the strength. In any case, the drying process is performed within a temperature range where the water glass does not vitrify.

By the above-mentioned drying treatment, a mold having a predetermined strength for the whole mold, that is, a strength that does not damage during casting is obtained. That is, the hardness of the entire mold is substantially uniform.
However, the water glass of this mold is not vitrified.

The mold obtained as described above is used for casting. In this case, the molten metal to be poured is Al alloy or M
In the case of g alloy, the melt temperature is around 720 ° C,
The cold mold surface is about 400 by contact with the molten metal.
The water glass does not vitrify because it drops to around ℃.

When removing the casting mold (core) after casting, if the casting product is submerged in water, the casting product will disintegrate and separate from the casting product so that the casting sand will dissolve. When the water temperature is 50 ° C. or higher, the disintegration proceeds rapidly, which is preferable.

When the mold subjected to the above drying treatment is not used immediately for casting, it is stored again in a dry indoor place so as not to absorb moisture in the air, and the required strength is maintained. It is desirable to make it dripping.

[0020]

[Example] 1.5% of water glass was added to a molding sand for cores and kneaded, and the mixture was filled in a mold having air permeability.

Next, hot air at 100 ° C. was passed through the mold to carry out a drying treatment to produce a core. When an aluminum alloy was cast using the obtained core, it was possible to perform casting while maintaining sufficient strength of the core, as in the core used in the related art. Next, when the casting product containing the core was immersed in water at 50 ° C., the molding sand forming the core collapsed so as to dissolve in water. It should be noted that this disintegration can proceed more quickly if the cast product is submerged in water before it reaches room temperature.

[0022]

EFFECTS OF THE INVENTION In the mold manufacturing method according to the present invention, 1 to 4% of water glass is added and kneaded to foundry sand, and the mold is molded using this, followed by drying to manufacture the mold. A mold having a desired strength can be easily obtained. Also,
When drying is performed with warm air of 80 to 120 ° C,
The drying process can be shortened. When the mold is a core, the core can be easily manufactured.

The mold disintegration method according to the present invention is carried out by adding 1 to 4% (% by weight) of water glass to a molding sand, kneading the mixture, molding the mold using this, and drying the resulting mold. Since it is soaked in water and disintegrated, the foundry sand can be easily removed from the foundry product. In addition, the temperature of water is 5
When the temperature is 0 ° C. or higher, the disintegration of the template can be accelerated. Furthermore, when the mold is a core, the core can be effectively disintegrated.

Claims (6)

[Claims] 1. Water glass is added to foundry sand in an amount of 1 to 4% (% by weight).
A method for producing a mold, which comprises adding and kneading, molding a mold using the mixture, and then drying the mixture to produce a mold. 2. The method for producing a mold according to claim 1, wherein the drying is performed with hot air of 80 to 120 ° C. 3. The mold manufacturing method according to claim 1, wherein the mold is a core. 4. 1-4% (wt%) water glass on the foundry sand
A method for disintegrating a mold, which comprises adding and kneading the mixture, molding the mold using the mixture, and then immersing the resulting mold in water to disintegrate it. 5. The method according to claim 4, wherein the water temperature is 50 ° C. or higher. 6. The method for disintegrating a mold according to claim 4, wherein the mold is a core.