JP3178297B2 - Method for transferring Cu or Cu alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to oxygen (O ₂₎ and deacidification with lysis step a melt of Cu or Cu alloy has a concentration of 10ppm or less, relates to a method of Utsuriyu the casting process, In particular, the present invention relates to a method for transferring Cu or Cu alloy in which the O ₂ concentration in the molten metal is prevented from increasing at the time of transferring the molten metal.

[0002]

2. Description of the Related Art Cu and Cu alloys (hereinafter sometimes referred to as Cu alloys) are good conductors of electricity and heat and are also excellent in workability. Widely used in By the way, Cu
The properties of the alloy products are affected by the O ₂ concentration in the Cu alloy,
In general, reduction of O ₂ concentration leads to improvement of product quality,
It is considered that the O ₂ concentration in the Cu alloy is preferably as low as possible. For this reason, in the melting and casting process of the Cu alloy, various molten metal deoxidation methods and measures to prevent reoxidation of the deoxidized molten metal have been conventionally performed.

As a molten metal deoxidation method, a method called poling has been known for a long time. In this method, raw pine logs are put into the molten metal, and Cu ₂ O in the molten metal is reduced by a gas such as CO or H ₂ emitted from the raw wood. The present inventors have also proposed a molten metal deoxidation method as disclosed in JP-A-5-25559. In this technique, after a solid reducing agent such as charcoal is sprayed on the surface of the molten Cu alloy, an inert gas such as Ar gas is blown into the molten Cu alloy and / or an inert gas is sprayed on the surface of the molten Cu alloy. This configuration makes it possible to remove generated CO ₂ gas in the molten metal and from the surface of the molten metal as quickly as possible. On the other hand, as measures to prevent the deoxidized molten metal from re-oxidizing, the surface of the molten metal is usually covered with a carbon-based solid reducing agent,
A method of using a reducing gas atmosphere such as O gas has been used. With these molten metal deoxidation methods and reoxidation prevention measures,
A certain effect has been obtained.

[0004]

However, as a practical matter, the fact is that the ingot finally obtained contains a larger amount of O ₂ than desired. That is, even if the O ₂ concentration is treated deoxidation obtained following JIS oxygen-free copper levels of the molten metal 10ppm in a melting furnace and cast according to conventional processes, the O ₂ concentration in the obtained ingot is at least 15 ~
It is generally about 20 ppm, and it is extremely difficult to maintain the O ₂ concentration level obtained in the melting furnace in the ingot as it is. This is thought to be due to mixing in the molten metal for some reason when the molten metal deoxidized in the melting furnace is transferred to the casting machine.

[0005] Therefore, in order to produce an oxygen-free copper level ingot capable of exhibiting extremely good properties, a vacuum melting method or a vacuum casting method is used, or a special melting facility is used. However, there is a problem in terms of productivity or cost.

The present invention has been made to solve such technical problems in the prior art, and an object of the present invention is to prevent the O ₂ concentration in the molten metal from increasing at the time of hot water transfer, and It is an object of the present invention to provide a method for transferring Cu or a Cu alloy capable of producing an ingot of oxygen-free copper level even in a melting and casting facility.

[0007]

According to the present invention, which has achieved the above object, there is provided a method for producing a molten copper or Cu alloy having an oxygen concentration of 10 ppm or less by a deoxidizing treatment in a melting step.
When the molten metal is transferred to the casting step, at least the molten metal drop portion having a drop height of 20 mm or more is covered with a cover member among the molten metal drop portions existing during the process of transferring the molten metal from the melting furnace to the casting machine. This is a method for transferring Cu or a Cu alloy having a gist in forming an inert gas flow.

In the above method, an inert gas introduction hole and an inert gas discharge hole are provided in the cover member, and the inert gas is introduced from the inert gas introduction hole at a flow rate of 0.2 times / min or more of the volume of the region. It is effective to adopt a configuration in which the inert gas is introduced from the inert gas discharge hole while introducing the gas, so that the effect of the present invention is maximized.

[0009]

The present inventors have studied from various angles the cause of an increase in the O ₂ concentration in a molten Cu alloy (or Cu) when a molten metal is transferred from a melting furnace to a casting machine. as a result,
It has been found that the molten metal drop existing during the molten metal transfer process from the melting furnace to the casting machine has a great effect on the increase in the O ₂ concentration. That is, in the hot water transfer process, as shown in FIG. Between the casting machine 4 and the casting machine 4, there is a molten metal head 5 which cannot be eliminated due to its structure. ₍₂ ) It was found that it greatly affected the increase in concentration. This is probably because the molten metal 6 flows as if it were a waterfall in the molten metal head 5, and the surface area of the molten metal 6 increases rapidly, and it is difficult to coat the molten metal head 5 with a solid reducing agent or the like. It is considered that the molten metal 6 absorbs O ₂ in the outside air at this portion because the molten metal 6 is exposed to the outside air during the hot water transfer process.

The present inventors have further studied from the viewpoint of preventing the absorption of O ₂ in the molten metal drop section 5. As a result, if the molten metal head 5 having at least a predetermined falling height among the molten metal heads 5 is covered with a cover member described below and an inert gas flow is formed in the covered area, O ₂ to the molten metal 6 can be formed. the absorption is prevented, reduced O ₂ concentrations in melting furnace without increasing the Utsuriyu process, mass cast while maintaining the O ₂ concentration is found that can be produced, and have completed the present invention.

The inventors of the present invention have investigated the relationship between the height of the molten metal head 5 and the increase in the O ₂ concentration of the molten metal 6 with the molten metal head 5 exposed to the outside air. The results shown in FIG. Obtained. The conditions for dissolution and hot water transfer are as follows. (Melting / migration conditions) Melt type: Pure Cu (Initial O ₂ concentration in the melt: 10 ppm) Melt temperature: 1200 ° C. Width of the gutter 2: 500 mm Melt depth: 300 mm Melt flow rate: 40 kg / min

As is apparent from FIG. 2, when the height of the molten metal drop 5 becomes 20 mm or more, the O ₂ concentration in the molten metal 6 becomes 10%.
ppm (that is, the O ₂ concentration in
pm or more) and the initial goal of obtaining oxygen-free copper levels with O ₂ concentrations of 10 ppm or less is no longer achieved. According to the present invention, as shown in the examples described below, even under such a situation, it was possible to prevent the absorption of O ₂ during the process of hot water transfer and maintain the O ₂ concentration in the molten metal at 10 ppm. . That is, the present invention needs to be implemented at least in the molten metal drop portion 5 where the drop height is 20 mm or more.

As described above, the present invention is characterized in that the molten metal head 5 is covered with the cover member 7 and an inert gas flow is formed in the covered area. The specific configuration was also discussed. As a result, for example, between the melting furnace 1 and the hot water gutter 2, FIG.
In addition, as shown in FIG.
The periphery of the molten metal drop portion 5 is covered with a cover member 7, and an inert gas introduction hole 9 and an inert gas discharge hole 10 are provided in a region 8 covered by the cover member 7. It has been found that a configuration in which an inert gas such as Ar is introduced from above and the gas is discharged from the inert gas discharge hole 10 to form an inert gas flow in the region 8 is particularly effective. In FIG. 3, reference numeral 11 denotes a solid reducing agent sprayed on the surface of the molten metal 6, and the melting furnace 1 is tilted in the direction of arrow A when the molten metal is poured.

The inert gas used at this time is in the region 8
It is preferable to introduce at a flow rate of 0.2 times / min or more of the volume. That is, FIG. 5 is a graph showing the relationship between the flow rate of the inert gas (the ratio to the volume of the region 8: times / minute) and the amount of increase in O ₂ in the molten metal 6. It can be seen that the amount of increase in O ₂ in the molten metal 6 is extremely suppressed when the time is equal to or longer than minutes. The conditions at this time were as follows, except that Ar (Ar gas pressure: 5 kg / cm ² ) was used as the inert gas.
The case of FIG. 2 was the same. As described above, the amount of increase in O ₂ in the molten metal 6 varies depending on the flow rate of the inert gas because no matter how the molten metal head 5 is cut off from the outside air by the cover member 7, air passing through a small gap, Alternatively, it is considered that air or the like accompanying the surface of the molten metal 6 is absorbed into the molten metal 6 by the stirring effect in the molten metal head 5. Therefore, setting the flow rate of the inert gas as described above is extremely important in securing the inert gas atmosphere and preventing the absorption of O ₂ into the molten metal 6 even under the above-described circumstances. It is significant.

The material of the cover member 7 used in the present invention is not particularly limited as long as it can cover the periphery of the molten metal drop portion 5 and has heat resistance, and includes various metal materials and refractories. . The inert gas to be used is not limited, and nitrogen, helium, or the like can be used in addition to the Ar gas described above and in the following examples.

In the present invention, the molten metal head 5 existing during the hot water transfer process is covered by the cover member 7, and the effect is obtained when the molten metal head 5 is applied to the molten metal head 5 having a drop height of at least 20 mm as described above. It is exhibited in. Therefore, as will be described later, the effect of the present invention can be achieved even if the molten metal dropping portion 5 covered by the cover member 7 is selected only at a position where the drop height is 20 mm or more. However, all the molten metal heads 5 (the height of which falls 20 m
m) is covered with the cover member 7,
Of course, the area 8 may be shielded from the outside air.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples are not intended to limit the present invention. It is included in the technical scope.

[0018]

【Example】

Example 1 Pure Cu and a Cu alloy (Cu-Fe system) were melted and deoxidized under the following conditions, and a molten metal having an O ₂ concentration of 7 ppm was obtained. (Melting condition) Melting furnace: High frequency induction furnace (5t) Melting temperature: 1200 ° C Deoxidizing treatment: Charcoal cover + Ar gas injection (20Nl / min)

The obtained melt is placed in a melting furnace (outlet diameter: 1).
(50 mm) through the molten metal head 5 having a drop height of 50 mm, and the molten metal was transferred to the hot water gutter 2 at a flow rate of 50 kg / min. At this time, the molten metal head 5 was covered with a cover member 7 as shown in FIG. The volume of the blocked area 8 was 1 m ³ , and an air flow was formed in the area 8 by introducing Ar gas at a flow rate of 0.2 m ³ into the area 8. When the O ₂ concentration in the molten metal 6 after being transferred to the transfer trough 2 was measured, it was 7 to 8 ppm, and hardly increased.

The molten metal 6 is then transferred to the casting machine 4,
Casting was performed. The surface of the molten metal 6 at this time was covered with graphite powder (solid reducing agent). After the molten metal was transferred to the casting machine 4, the molten metal 6 was cast by semi-continuous casting of 50 mm / min (300 mmφ × 5 pieces), and the O ₂ concentration of the obtained ingot was measured. Met.

[0021] Example 2 pure Cu and Cu alloys (Cu-Ni-based), was dissolved and treated deoxidation under the following conditions, O ₂ concentration is 10ppm
Was obtained. (Melting conditions) Melting furnace: Shaft furnace (5 t / hr) Melting temperature: 1200 ° C Deoxidation treatment: Combustion adjustment of shaft furnace + material adjustment

The obtained molten metal 6 is discharged from a shaft furnace and transferred to a hot water trough 2 (width: 300 mm, depth: 200 mm). 5 and flowed to the casting gutter 3 at a flow rate of 40 kg / min. At this time, the molten metal drop portion 5 was covered with a cover member 7 as shown in FIG. The volume of the blocked area 8 was 0.5 m ³ , and an Ar gas was introduced into the area 8 at a flow rate of 0.1 m ³ to form an air flow in the area 8. Further, the surface of the molten metal 6 was covered with graphite (solid reducing agent) from the time when the molten metal was discharged from the shaft furnace to the time when the molten metal 6 reached the casting machine 4. O in molten metal 6 on hot water gutter 2
_{2 When the} concentration was measured, it was 10 ppm, and there was almost no increase.

After the molten metal 6 is transferred to the casting machine 4, the molten metal 6 is subjected to semi-continuous casting of 30 mm / min.
Was cast (300 mm square x 2 pieces), and the O ₂ concentration of the obtained ingot was measured.

[0024]

As described above, according to the method of the present invention, it is possible to prevent the oxygen concentration in the molten metal from increasing at the time of hot water transfer, and even in a general melting / casting facility, It has become possible to produce copper level ingots.

[Brief description of the drawings]

FIG. 1 is a schematic view for explaining a general molten metal transfer process.

FIG. 2 is a graph showing the relationship between the height of a molten metal drop 5 and the increase in the O ₂ concentration of the molten metal.

FIG. 3 is a schematic explanatory view showing a state where a molten metal drop portion 5 between a melting furnace 1 and a hot water gutter 2 is covered with a cover member 7;

FIG. 4 is a schematic explanatory view showing a state where a molten metal drop portion 5 between the hot water transfer gutters 2 is covered with a cover member 7;

FIG. 5 is a graph showing a relationship between a flow rate of an inert gas and an increase amount of O ₂ in a molten metal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Transfer gutter 3 Casting gutter 4 Casting machine 5 Molten head 6 Molten 7 Cover member 8 Area 9 Inert gas introduction hole 10 Inert gas discharge hole 11 Solid reducing agent

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kiyomasa Oga 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Research Institute (72) Inventor Motohiro Arai Nishi-ku, Kobe-shi, Hyogo 1-5-5 Takatsukadai Kobe Steel, Ltd.Kobe Research Institute (72) Inventor Hirofumi Okada 14-1, Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Kobe Steel, Ltd.Nagofu Works (72) Inventor Eiji Yoshida 14-1, Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Inside the Kofu Steel Works Chofu Works (72) Inventor Joji Masuda 14-1, Nagafu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Inside the Kofu Steel Works Chofu Works (56) References JP-A-53-80331 (JP, A) JP-A-5-25559 (JP, A) JP-A-60-180998 (JP, U) JP-A-59-34839 (JP, U) (58)査the field (Int.Cl. ^7, DB name) B22D 35/00 B22D 11/00

Claims (2)

(57) [Claims] When a molten metal of Cu or a Cu alloy whose oxygen concentration is reduced to 10 ppm or less by a deoxidizing treatment in a melting step is transferred to a casting step, the molten metal is present in a step of transferring from a melting furnace to a casting machine. A method for transferring Cu or a Cu alloy, comprising: covering at least a molten metal drop portion having a drop height of 20 mm or more with a cover member, and forming an inert gas flow in the covered area. 2. An inert gas introduction hole and an inert gas discharge hole are provided in the cover member, and an inert gas is introduced from the inert gas introduction hole at a flow rate of 0.2 times / minute or more of the volume of the region. 2. The hot water transfer method according to claim 1, wherein the hot water is discharged from the inert gas discharge hole.