JP2001347340A - Coating agent for lost pattern casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating agent for casting by which handling time for casting operation can be saved, and also, the appearance of a cast product can be made satisfactory. SOLUTION: In this coating agent for casting to be adhered to the surface of a lost pattern, its volume ratio to an aggregate is controlled to 10 to 35%, and also, graphite is incorporated so that, after sintering, its color is made the one similar to that of the surface of the casting to be cast to composes the coating agent for casting. In this way, residues are small, also, the difference between the color of the surface of the cast product and the color of the coating agent is made small, and even in the case the coating agent remains on the surface, it is not treated as a defective in casting or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting mold for a vanishing model, and more particularly to a casting mold capable of easily performing a surface finishing treatment of a casting after casting and reducing the labor of a casting operation.

[0002]

2. Description of the Related Art Casting molds are applied to the surface of a cast product by a vanishing model casting method in order to satisfactorily finish the surface of a cast product and prevent casting defects. The mold was applied to a predetermined thickness by using a brush or by immersing the disappearance model in a solution of the mold.

The purpose of using a mold is to improve the seizure resistance. However, when the density of the mold is large, the model made of expanded polystyrene is deformed or damaged by weight, and the model is heavy because the model is heavy. It may be difficult to transport and hinder productivity. In addition, if the mixing ratio of the coating mold is not appropriate, the amount of the residue may increase, or scavenging may occur due to thermal expansion. For this reason, the components contained in the mold are appropriately combined according to the type and size of the cast product, the required accuracy, and the like, and according to the main purpose.

Then, casting is performed by a vanishing model casting method,
When removing the cast product from the mold, the mold applied to the disappearing model along with the casting sand adheres to the surface of the product,
Shot blasting or the like has been performed to remove adhering foundry sand and coating mold from the cast product.

[0005]

However, in the case where the shape of the cast product is complicated or the surface of the product has a narrow recess or the like, the mold may remain in such a portion even when shot blasting is used. In the conventional coating mold, the compounding component is determined by the action in casting, and matching with the color of the surface of the cast product has not been considered. For example, graphite
It has the effect of preventing the seizure by deteriorating the wettability between the mold and the molten metal, but in the vanishing model casting method, graphite is often not used for the mold when the product is small. In the case of large items, graphite is added to reduce the density of the coating mold and prevent deformation of the expanded polystyrene model, and may contain 35% or more graphite by volume ratio with the aggregate. .

Therefore, if a carbon component such as graphite is appropriately added according to the purpose, the color of the mold differs from the color of the cast product. If the mold remains on the surface of the cast product, the color of the portion becomes the color of the product. On the other hand, not only the appearance was spoiled, but also the post-casting treatment was considered to be inadequate, and even though the casting operation was performed without any problem, it seemed that there was a casting defect. In addition, if it is attempted to completely remove the remaining coating mold from the surface of the cast product, the removing operation takes time and effort, and increases the cost.

FIG. 3 shows the relationship between the graphite content and the residue of a cast product. As shown in FIG. 3, there is a problem that the residue increases as the graphite content increases. In particular,
It can be seen that when the Kurokami content exceeds 35% by volume, the residue rapidly increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a casting mold capable of solving the above-mentioned problems, eliminating the trouble of casting work, and improving the appearance of a cast product.

[0009]

According to the present invention, in order to solve the above-mentioned problems, the content of the carbon component in the coating mold is within the range of 10 to 35% by volume relative to the aggregate, and the casting is carried out. A mold was formed so as to have a color equivalent to the color of the surface of the casting later. Further, the linear thermal expansion coefficient of the coating mold up to 1500 ° C. is 0.08.
% Or less. In order to reduce the coefficient of linear thermal expansion, the content of carbon in the fused silica as the main aggregate is reduced. The density after drying was 1.5 g / cm ³ .

[0010] Thereby, it is possible to satisfy the requirements required as a casting mold in casting, perform a good casting operation, and even if the casting mold remains on the surface of the casting after casting,
It cannot be determined from the appearance of the casting, and does not impair the appearance. Even when thermal expansion occurs due to a carbon component such as graphite, no scooping occurs because the linear thermal expansion coefficient is set to 0.08% or less.

Therefore, it is not necessary to forcibly remove the mold by the removing operation, so that the labor and cost can be greatly reduced, and a good cast product can be obtained. Also, the density of the main aggregate is much smaller than that of alumina or zircon coating by using fused silica, so there is no deformation or breakage of the model, and the workability is large even for large castings. Can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The casting mold of the present invention will be described below.

FIG. 2 shows an example of casting. FIG. 2 shows casting by the vanishing model casting method. First, the vanishing model 10 is installed inside a casting flask 12, and casting sand 14 is charged and buried. The vanishing model 10 is made of styrene foam having a hole portion 13, and a coating mold 2 is applied to the entire surface in advance to a predetermined thickness.

In the coating mold 2, the aggregate is fused silica, and the amount of carbon added is 35% so that graphite as a carbon component becomes a color similar to the color of the surface of the cast product. An appropriate amount is contained within the following range. Further, other necessary components are added to the coating mold 2 as appropriate. Further mold 2
Is adjusted such that the coefficient of linear thermal expansion is 0.08% or less.

The molten metal is poured from the gate 16 to produce a cast product. After the casting, the casting frame 12 is released and the cast product is taken out, and then shot blasting is performed on the entire surface of the cast product to remove the coating mold 2 and the molding sand 14 attached thereto. Coating mold 2
Is made to have the same color as the surface of the cast product by adding an appropriate amount of graphite.
Even if the mold 2 remains on the surface of the cast product, such as inside, the color is the same, so it is almost impossible to visually determine whether the mold 2 remains on the surface of the cast product. No scooping or the like was observed.

Therefore, no inconvenience occurs even if the mold after casting is not completely removed, and a cast product with much reduced labor and cost after casting can be obtained.

If the cast product is large, for example, if the weight of the product is 10,000 kg or more, the density of the coating mold 2 after drying is 1.5 g / cm ³ or less. With such a setting, a good cast product can be obtained without deformation of the disappearing model due to the weight of the applied coating mold 2, and productivity can be improved.

Experimental Example Next, an experimental example of a coating mold will be described. In the experiment, the aggregate was made of fused silica, the amount of scaly graphite as a carbon component was changed from 0% to 60%, and the composition was changed every 5 to 10%, and 8% of clay was added thereto to form a mold. . Further, a small amount of a surfactant, a styrene-based binder and water are added for dispersion and thickening, and the density after drying is 1.5 g / cm.
A coating pattern of Baume 60 was manufactured as ³ or less.

In the experiment, using a vanishing model 10 having a shape as shown in FIG. 2, each mold was applied to a predetermined thickness.
It was manufactured by pouring. After casting, the product was unframed and the product was taken out, followed by shot blasting to remove the coating mold and the like adhering to the surface. Then, a comparison was made between the casting mold surface remaining in the concave portion of the product and the casting surface because shot blast did not reach sufficiently.

The results are shown in FIG. When the carbon content was 0% or 5%, the color of the mold was white and the residual was conspicuous on the casting surface. When the content exceeded 35%, the color of the mold became close to black and became blacker than the color of the surface of the casting, and in this case, the residual was conspicuous.

Thus, the graphite content is 10% or more and 35% or more.
% Or less, and preferably in the range of 20% to 25%, the color difference from the casting is small and good.

The state of the residue is shown in the right column of FIG. The residue area was obtained by grinding the upper surface 11 of the cast product 10 by 5 mm and measuring the area of the residue portion in that state. As shown in FIG. 1, the residue area increases as the amount of graphite increases. This shows that the graphite content of 35% or less is a range that does not cause the problem of the residue of the cast product.

The carbon component contained in the coating mold 2 may be earth graphite, anthracite, electrode scrap, or quiche graphite, instead of scaly graphite as in the above example. In addition, other than fused silica, white aggregates such as natural silica, mullite, alumina, and magnesia may be used. still,
When the respective components are different, the densities are different, so that the volume ratio of the scale graphite and the other carbon components changes accordingly.

[0024]

According to the casting mold of the present invention, the residue of the casting after casting is small, and since the casting mold has the same color as the casting surface, even if the casting mold remains on the surface, There is no appearance defect of the cast product, there is no need to completely remove the coating mold after casting, and labor and cost can be reduced, and since the colors are similar, it is misunderstood that there is a casting defect. There is no.

Further, the density of the coating after drying is 1.5 g / c.
By set to m ³ or less, even when applied to evaporative pattern, can be deformed to model the weight of the coating type without obtaining good cast product.

[Brief description of the drawings]

FIG. 1 is a diagram showing experimental results.

FIG. 2 is a state showing a casting state.

FIG. 3 is a diagram showing the relationship between graphite and residues.

[Explanation of symbols]

 2 Coating mold 10 Disappearance model 11 Top surface 12 Casting frame 13 Hole 14 Casting sand 16 Gate

Claims (2)

[Claims] 1. A casting mold for applying to a surface of a disappearing model, wherein a volume ratio of the casting mold is 10 to 35% with respect to an aggregate, and after the casting, a color similar to the color of the surface of the casting is obtained. A coating mold for casting, characterized by containing an amount of a carbon component. 2. The main aggregate is made of fused silica at 1500 ° C.
The coefficient of linear thermal expansion up to 0.08% or less, and the density of the mold after drying is 1.5 g / cm ³ or less, the mold for vanishing model casting according to claim 1, characterized in that: .