JPS6157105B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a spheroidizing method.

Conventionally, the most common method for manufacturing spheroidal graphite cast iron is to place alloy ingots, alloy grains, or alloy powder in a ladle for spheroidization treatment, and then process the molten cast iron by flowing it into the ladle. It was

There is also a method of pouring molten cast iron into a mold and adding a granular spheroidizing agent to make it spheroidized (for example, Japanese Patent Publication No. 1855/1983).

Recently, a method has been used in which alloy grains or alloy powder for spheroidizing treatment are placed in a mold, molten cast iron is poured, and then the molten metal is spheroidized within the mold.

However, in the method of spheroidizing the molten metal in a ladle, it is not possible to perform the spheroidization process immediately before pouring the molten metal into the mold, and it takes time to pour the molten metal after the spheroidization process. material (e.g. Mg
In some cases, the so-called fading phenomenon occurs, which is the disappearance of metals (alloys, etc.).

In addition, in the method of adding a powder spheroidizing agent while injecting molten cast iron into the mold, substances that do not completely react remain as inclusions, which significantly shortens the life of the cutter in later machining and impairs machining accuracy. There are drawbacks that make it worse. Furthermore, when the powder comes into contact with molten metal, it oxidizes and generates oxides (slag), which leaves a large amount of dross in the casting, which is unfavorable in terms of quality and has poor castability.

Also, in the latter method of spheroidizing in the mold,
The spheroidizing alloy did not completely dissolve into the molten cast iron, and as a result, so-called segregation occurred, in which spheroidized portions and non-spheroidized portions were formed.

The present invention was invented to solve these drawbacks, and is a spheroidizing method characterized by injecting a molten spheroidizing material into molten cast iron at the time of pouring the molten cast iron into a mold. It is.

The method will be explained in detail below. In the figure, 1 is a melting furnace for molten spheroidized material, 2 is the molten metal,
3 is a ladle for molten cast iron, 4 is molten cast iron, 5 is a mold,
5a and 5b are mold pouring ports.

In the present invention, first, oxides (slag) of the molten cast iron and the molten spheroidized material are removed separately. As one of the spheroidizing treatment methods in which molten cast iron and molten spheroidized material are reacted immediately before pouring, as shown in FIG. A spheroidized molten metal 2 is added to a hot water ladle 3 from a treated material melting furnace 1 or a ladle (not shown), and the treated molten metal is poured into a mold 5.

Next, as shown in Fig. 2, the spheroidizing method involves pouring the respective molten metals from the ladle 3 filled with molten cast iron 4 and the melting furnace 1 or ladle filled with molten cast iron 2 into the mold 5. , a ladle 3 containing molten cast iron 4 and a spheroidized molten metal 2 are placed above the pouring port 5a of the mold 5.
The melting furnace 1 and the ladle are positioned and the molten metals 2 and 4 are poured into the mold 5 from both of them.
4 reacts so that the molten cast iron becomes spheroidized.

Further, as shown in FIGS. 3 and 4, a pouring port 5a for molten cast iron 4 and a pouring port 5b for molten spheroidized material 2 are separately provided in the mold 5, and both melting furnaces 1 and ladle 3 are provided separately. Pour the molten metals 2 and 4 from the pouring port 5, respectively.
There is also a method of pouring the metal into the mold 5 from b, 5a and performing the spheroidization treatment within the mold 5.

When Fe-Si-Mg alloy is used as a spheroidized material, conventionally the minimum weight percentage of Mg is about 2%, but using this, the residual Mg in spheroidal graphite cast iron is 0.04% or more. However, according to the method of the present invention, the amount of Mg in the Fe--Mg alloy may be 1% by weight or less, and spheroidized graphite cast iron can be obtained even with 0.1% by weight of Mg.

Note that the melting temperature of Fe-Si-Mg is preferably 1300°C or lower, preferably about 1300°C to 1200°C. Also,
The smaller the temperature difference with the molten cast iron (approximately 1400℃), the smoother the reaction will take place.

Since the present invention is as described above, it has the following effects.

(1) The amount of spheroidized metal (for example, Mg, etc.) may be small.

(2) Fading phenomenon can be prevented.

(3) There is no need to set the spheroidized material inside or outside the mold.

(4) Segregation is eliminated and sound castings can be easily produced.

(5) Since there is no need to melt the spheroidizing alloy with molten cast iron, the temperature of the molten cast iron does not have to be higher than necessary, so the melting furnace lasts longer.

(6) Since oxides generated by melting the spheroidized material can be removed before injection, dross generation is prevented and castability is improved.

[Brief explanation of the drawing]

1 to 4 are schematic illustrations for explaining the method of the present invention. DESCRIPTION OF SYMBOLS 1... Melting furnace for molten metal of spheroidized material, 2... Molten metal of spheroidized material, 3... Ladle for molten cast iron, 4... Molten cast iron, 5... Mold, 5a, 5b... Pouring spout.

Claims (1)

[Claims] 1. A spheroidizing method characterized by injecting a molten spheroidizing material into molten cast iron when pouring the molten cast iron into a mold.