JPH0347648A - Exothermic heat insulating method for casting mold - Google Patents

Abstract

PURPOSE:To impart a heat insulating effect to the casting mold and to produce a deflectless casting by pouring a molten metal into the casting mold which is coated with a facing material consisting of a far IR radioactive material as aggregate or the casting mold inserted with a plate molding in a facing sand. CONSTITUTION:The far IR radioactive material is a metal oxide, nitride, carbide and the combined materials thereof and has preferably the prescribed emissivity of a prescribed wavelength. The simple material thereof or the combined materials are calcined at and for a prescribed temp. and time. Both of a graphite facing material and white color facing material are usable as the facing material used as the aggregate of a mold coat. KIBUSHI clay is added and mixed as a binder so and with the far IR radioactive material, then kneading the power under addition of water, press-molding the mixture to a prescribed form and calcining the molding at and for the prescribed temp. and time in the case of using this powder by inserting the powder as the plate molding into the facing sand. The heat insulating effect is imparted to the casting which is a thin casting and attains a rapidly cooled structure, by which the defectless casting is produced.

Description

Detailed Description of the Invention Field of Industrial Application This invention coats a mold with a far-infrared radioactive substance or buries a plate molding in skin sand, heats the mold by injecting molten metal, and heats the mold. This invention relates to a method for preventing rapid cooling.

Summary of the Invention This invention is based on the difference in cooling rate between thick and thin parts of the product when casting castings (to make the structure change uniform, or to prevent rapid cooling of thin-walled castings). Applying a coating mold made of far-infrared radioactive material to the thin-walled parts or the entire mold of thin-walled castings, or burying molded plates of the same material in the mold skin sand, and pouring molten metal into the mold will produce far-infrared rays. This radiation causes a part or the whole of the mold to generate heat, thereby preventing a uniform structure of the casting or a rapid cooling structure of the thin-walled casting.

Conventional technology Traditionally, heat-generating heat insulators for molds have been used in the powder type, which is sprayed after pouring molten metal into the sprue or riser area, or in the form of a slab or plate molded from water glass, which is applied to the mold inlet (rather than the riser). There is a heat-generating heat insulating agent buried in the parts.

These are alumina thermite methods, in which metal oxide and aluminum are mixed in powder form and ignited to utilize the heat of the oxidation reaction of aluminum. Its chemical components consist of aluminum, aluminum oxide, silicon oxide, iron oxide, tri-iron oxide and reaction promoter. It is clear that the metal oxides among these are not subjected to firing treatment and are not far-infrared emitting materials. There is a problem in that a large amount of harmful gas is generated during the thermite reaction, and when a powder heat-generating heat insulating agent is added, a large amount of dust is scattered along with the generated gas, resulting in a deterioration of the working environment. .

Problems to be Solved by the Invention This invention utilizes the fact that far infrared rays generated by far infrared radioactive substances are absorbed by the mold material and generate heat.
After pouring molten cast iron for more than 0 minutes, the casting temperature is 100
It maintains heat generation from 0°C to 500°C and maintains the surface sand temperature of 400°C, showing the effect of preventing rapid cooling of castings, and preventing the dispersion of harmful gases and dust. This was done to provide a way to keep warm.

Means for solving the problem, that is, the present invention, involves applying a coating mold made of far-infrared radioactive material as an aggregate to a casting mold, or burying a molded plate in sand and injecting molten metal into the mold. This invention relates to a method of heat generation and heat retention for a mold, which is characterized by its characteristics.

The far-infrared emitting substance is preferably a metal oxide, nitride, carbide, or composite thereof, and has an emissivity of 9096 or more over a wavelength range of 5 microns to 20 microns. For this purpose, 13 of these simple substances or combinations are used.
It is necessary to bake at 00°C for 1 hour.

The coating agent used as the aggregate for the coating mold can be either a graphite-based mold coating agent or a white-based mold coating agent.

The coating thickness of the mold coating agent is usually 1 to 3 mm; if it is too thin, the heat generating effect will be weakened, so it is effective to apply the mold coating agent multiple times to increase the thickness.

When used as a plate molded product buried in skin sand, this material is mixed with far-infrared radioactive material powder as a binder, then water is added, kneaded, and pressure-molded into the specified shape. , and bake at 1300°C for 1 hour.

When using this clay as a binder, the amount added is 8 to 10
96 is appropriate, and moisture content is preferably 8 to 1296.

A sufficient heat retention effect can be obtained when the thickness of the plate molding is 3 to 51 nm.

Molds for applying the above-mentioned mold coating agent or molds for storing plate moldings include molds conventionally used in the field, such as synthetic sand molds (main binder: bentonite), organic self-hardening molds (furan The resin type), full mold type, carbon dioxide type, V process, etc. may be appropriately selected and used.

Effect: When molten cast iron (FC-25) is injected into a mold coated with a coating agent made of the far-infrared radioactive substance mentioned above or a mold in which a plate molding is buried in skin sand, the cooling temperature of the molten metal is slow. Thus, thin cast iron of 100 x 50 x s mm becomes white pig iron when the above-mentioned substance is not used, but gray cast iron with graphite precipitated was obtained.

Hereinafter, the present invention will be explained by examples.

Example 1 Far-infrared radioactive material (S L
02-Al□Q series) was applied as an aggregate using graphite coating material (3 mm thick) L, and the uncoated type was embedded in a flan mold of 200 x 120 mm and height 170 mm. , 1300°C cast iron (FC25)
The cooling rate of the cast iron in the mold was measured over time when molten metal was poured into the mold. The uncoated type showed a temperature of 970°C immediately after pouring the molten metal, but the one coated with the above coating agent showed a temperature of 1070°C.
5 minutes after injection, the temperature of the uncoated type was 560°C, and the temperature of the uncoated type was 760°C.
60°C, uncoated cast iron is white pig iron,
Gray cast iron was obtained from the coated mold.

Example 2 A Styrofoam mold model was embedded in the same furan mold as in Example 1, and a far-infrared radioactive material (SiO
z Al2O3 system) φ50 x 5mm disc plate 6
The cooling rate of the cast iron in the mold was measured over time when 1300°C molten cast iron (FC-25) was poured into the mold. The temperature immediately after pouring the molten metal was 1100°C, and the temperature 5 minutes after pouring was 800°C, and perfect gray cast iron was obtained.

Effects of the Invention According to the present invention, as a result of imparting a heat-retaining effect to a thin-walled casting that has a quenched structure (white pig iron in the case of cast iron), a sound casting can be manufactured.

Claims (1)

[Claims] 1. A method in which molten metal is poured into a mold in which a far-infrared radioactive substance is coated or a molded plate is buried in skin sand, and the mold is heated and kept warm by radiation of far-infrared rays.