JPS61154760A - Prevention of splash sticking - Google Patents

Abstract

PURPOSE:To prevent the sticking of a splash to a mold by coating vacuum grease to the wall surface of a crucible and executing a vacuum arc welding method (VAR). CONSTITUTION:The vacuum grease is coated to the wall surface of the crucible 1 to be used in the VAR which yields a steel or alloy by the melting and solidification of a material to be melted (consumable electrode) 2 in a vacuum. As a result, a film is formed by the combustion of the vacuum grease and the sticking of the splash 16 to the molded product is prevented. The vacuum grease is required to be coated to the upper part of the molten metal 17 surface of the crucible 1 as the splash 16 sticks more to the upper part of the surface 17 while the splash 16 melts again the lower part of the surface 17. The sticking of the splash 16 to the mold is prevented according to the above-mentioned method and therefore the steel ingot has a good surface and the VAR mold having extremely good quality is obtd. without the intrusion of foreign matter into the molten steel and without flawing of the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing splash adhesion of molded products in VAR.

[Prior art] V A R (Vacuum Are Remelzin)
The principle of g) is that, as shown in Figure 2, 2 tons of the material to be melted (consumable electrode) is melted in a water-cooled crucible, and the molten steel is solidified in the crucible, that is, melting and solidification. This is a method in which these steps are carried out one after another in small quantities under high vacuum, resulting in improved quality through vacuum separation, flotation of inclusions, and layered solidification.

In Fig. 2, 5 is a steel ingot, 4 is a jacket, 5 is a cooling water, 6 is a furnace body, 7 is a Fi consumable electrode lifting mechanism, 8 is a power source, 9 is a control board, 10 is a stayer rod, 111t stub holder, 12 indicates a stub.

In such a VAR, splash occurs due to electrode arcing, bubbling, and the like.

To explain this using Figure 1, 'tL pole 2 melts,
It becomes a droplet 13, forms a pool 14', and solidifies to form an ingot 15. At that time, a splash (pea-sized hot water balls 16 adhere to the wall of the crucible 1, and V
The splash 15 of the VC molded product (hereinafter simply referred to as mold) obtained by AR will adhere.

This type of splash not only adversely affects the steel ingot wind obtained by VAR, but also causes foreign matter to be mixed in, so it must be removed. It was done by mechanical methods, but
This not only requires manpower, but also increases the cost of one step in the removal process, resulting in an increase in the number of steps. In addition, mechanical removal of the resin causes an overhang on the mold, which has an adverse effect on the quality of the mold.

[Problem that the invention seeks to solve]

An object of the present invention is to completely prevent splash from adhering to the mold.

The aim is to avoid the input of manpower for this purpose.

Still another object of the present invention is to avoid damaging the mold for the purpose of removing splashes, and at the same time eliminate any negative effects on the steel ingot wind, and also avoid the incorporation of foreign matter.
The goal is to improve the quality of VAR molds.

[Means for solving problems]

The inventors of the present invention have conducted intensive studies on prevention of VAR splash adhesion, and have found that when vacuum grease is applied to the wall of the crucible and VARt is performed, the amount of splash adhesion to the mold is extremely reduced. Based on this, we have arrived at the present invention.

The present invention is a vacuum arc melting method (hereinafter referred to as VAR) in which the material to be melted is melted and solidified under vacuum, and the material is melted and solidified on steel or alloy.
, on the wall of the crucible used for the 1/AH,
The present invention relates to a method for preventing splash adhesion to a molded product in VARK, which is characterized by applying a substance that forms a complete film by burning the substance.

In the present invention, it is not clear why spray adhesion to the mold was prevented by applying vacuum grease to the wall of the crucible, but the grease
It is presumed that during the melting in AR, it burned, and a coating (carbon coating) made of the burned material was formed on the crucible, and the adhesion of splash was prevented based on the burrs. As mentioned above, a vacuum grill is preferable as the substance that forms a film through combustion.

The grease has little effect on the quality of the mold, and
Since it can be applied extremely thinly and uniformly, it is suitable for preventing splash adhesion according to the present invention.

In addition, an oily substance such as oil, varnish, etc. may also be used as the substance.

When applying vacuum glass, the splash 16 generated below the hot water level 17 is remelted;
Since the splash 16 adhered to the upper part of the hot water surface (No. 11 JI 7 ), it was found that it is better to apply it to the upper part of the hot water surface 17 of the crucible 1 .

〔Example〕

Example I G O, 40% (wt, same hereinafter), Ni 1.7%, O
Structural steel whose main components are Ro, 8%, and Mo 005% is coated at the coating height from the hot water surface as shown in Fig. 1 (X) t-500.
As a test, a VAR mold with no splash adhesion was obtained by applying vacuum fest (high vacuum grease, manufactured by ULVAC Service Co., Ltd.) and performing VhRl.

Although the vacuum grease burned during VARa disassembly, no gas generation was observed that would adversely affect quality.

It was also observed that the steel ingot had a good appearance.

Example 2 V
ARt- was performed and similar results were obtained.

Comparative Example 1 VAR as in Example 1 except that vacuum grease was not used.
When conducted, there was splash adhesion, which required a process of removing with pearls or spraying shot (steel grains), and the surface of the steel ingot was also poor compared to the product of the present invention.

Example 5 VAR was performed in the same manner as in Example 1 except that all oil was used instead of vacuum grease, and the same results as in Example 1 were obtained.

Example 4 VAR was performed in the same manner as in Example 1 except that varnish was used instead of vacuum grease, and the same results as in Example 1 were obtained.

〔Effect of the invention〕

(1) According to the present invention, by applying a splash prevention agent such as vacuum grease to the crucible wall surface, combustion can be prevented. Since the A film is formed and the adhesion of splash to the mold can be completely prevented, the conventional work of removing splash can be omitted, saving human labor and avoiding an increase in the number of steps.

(2) According to the present invention, since splash adhesion to the mold is prevented, the surface of the steel ingot is good, there is no contamination of foreign matter, there is no need to overhang the mold, and an extremely high-quality VAR mold can be produced. Obtained.

(31 Even if vacuum grease is used according to the method of the present invention, no gas is generated and there is no adverse effect on quality.
We were able to provide an industrially significant splash adhesion prevention technology.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of splash adhesion in VAR, and FIG. 2 is an example principle diagram of VAR. 1... Crucible 2... Material to be melted (consumable electrode) 16... Splash 14... Pool 15... Ingot

Claims (1)

[Claims] 1. In the vacuum arc melting method (hereinafter referred to as VAR) for obtaining steel or alloy by melting and solidifying the material to be melted under vacuum, the combustion A method for preventing splash adhesion to molded products in VAR, characterized by applying a substance that forms a film. 2. The method for preventing splash adhesion according to claim 1, wherein the substance that forms a film by combustion is vacuum grease. 3. Apply vacuum grease to the crucible wall above the hot water level.
A method for preventing splash adhesion according to claim 2.