JPH0687066A - Production of copper-coated steel wire - Google Patents

Abstract

PURPOSE:To produce a copper-coated steel wire capable of evading the breakage of a nozzle inserted with a seed wire arranged at the bottom part of a crucible and the breaking of the seed wire, uniform in the thickness of the coated layer and excellent in the adhesion of the coated layer and the seed wire. CONSTITUTION:The hole diameter of an equal diameter straight part 21b in a hole provided in a nozzle 21 arranged at the bottom part of the crucible 1 for holding molten copper is set at larger than the diameter of the steel wire as the seed wire 7 by 0.05-0.40mm and the length of this equal diameter straight part 21b is made to be 5-30mm. Further, the atmosphere of passage where the seed wire 2 enters to the crucible 1 after cleaning the surface of the steel wire is made to be inert gas or weak reducing gas atmosphere at 160-600mmHg absolute pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a copper-coated steel wire by a dip forming method.

[0002]

2. Description of the Related Art Conventionally, a dip forming method has been known as a method for manufacturing a copper rough drawn wire. FIG. 1 is a schematic sectional view showing a method for manufacturing a copper rough-drawn wire by the dip forming method.

The crucible 1 is made of a refractory material such as graphite, and a seed wire insertion portion 2 through which a seed wire 7 is inserted is provided at the bottom of the crucible 1. Further, the molten copper 5 is supplied to the crucible 1 from the melting furnace 3 through the molten copper supply port 4. Further, below the crucible 1, a housing 12 having a capstan 8 is provided. Seed line 7 is housing 12
After the surface layer has been removed by the peeling die 6 arranged at the entrance of the device, the film is wound on the capstan 8 and passes through the seed wire insertion part 2 from the capstan 8 to enter the crucible 1. Has become. In the crucible 1, molten copper is attached around the seed wire 7 to form a copper-coated wire 9.

Above the crucible 1, a cooling tower 10 is provided.
It is provided by connecting to. The copper-coated wire 9 pulled up from the crucible 1 is water-cooled in the cooling tower 10 and cooled to a predetermined temperature. Then, the copper-coated wire 9 coming out of the cooling tower 10 is continuously rolled by a hot rolling mill (not shown) and finished to have a predetermined diameter.

By the way, in JP-A-39-18204, the surface of the seed wire 7 whose surface layer has been removed by the skinning die 6 is kept clean, and the surface of the copper-coated wire 9 has defects such as blisters and pinholes. In order to prevent the occurrence of the above, a technique is disclosed in which a vacuum pump is connected to the exhaust port 13 provided in the housing 12 and the inside of the housing 12 is maintained in a vacuum atmosphere to manufacture a copper-coated wire. Further, in JP-A-60-184461, in order to reduce the equipment cost and maintenance cost of a vacuum pump or the like, the inside of the housing 12 is made to be an inert gas atmosphere having a pressure higher than atmospheric pressure or a weak reducing gas atmosphere. It is disclosed. Furthermore, since the seed wire insertion portion 2 which is exposed to high temperature and on which the seed wire 7 slides has excellent heat resistance and wear resistance, it is generally a bush member (nozzle) made of a Mo-based alloy or the like.
JP-A-60-255255 discloses that, when a steel wire is used as the seed wire, fine debris generated from the bushing member due to sliding of the seed wire 7 causes the seed wire and the copper coating layer. And zirconia-based ceramics, silicon carbide-based ceramics, or silicon nitride-based ceramics as the bushing member in order to prevent disconnection during wire drawing and deterioration of the efficiency of the wire drawing process. It is disclosed that it is formed of a ceramic material containing as a main component.

[0006]

However, when an attempt is made to manufacture a copper-coated steel wire by combining the above-mentioned methods, there are the following problems.

FIG. 2 is a sectional view showing the seed line insertion portion of the crucible. A nozzle 21 having a seed line insertion hole is attached to the bottom of the crucible body 1a. The lower portion of the seed wire insertion hole is a conical taper portion 21a that spreads downward to guide the seed wire 7, and the upper portion thereof is a constant-diameter linear portion 21b that is a cylindrical space. There is. This equal-diameter straight line portion 21b usually has a hole diameter smaller than the diameter of the seed wire 7.
The length is set to about 50 mm, and the length (vertical length) is set to about 20 mm.

When a copper-coated steel wire is manufactured by the conventional dip forming method, the housing 12 shown in FIG. 1 is used.
When the inside is evacuated, the molten copper at the bottom of the crucible receives a total pressure of the pressure corresponding to the height of the molten metal in the crucible and the external pressure (1 atm). That is, normally, since there is a bath height of about 800 mm in the crucible, in the case of pure copper molten metal, about 0.7 atmospheric pressure is applied to the molten copper at the bottom of the crucible by the pressure,
If it is made anti-vacuum, a pressure of about 1.7 atm is being applied. In this way, when the inside of the housing is evacuated, about 1.
Since a large pressure of 7 atm is applied to the molten copper at the bottom of the crucible, the nozzle 21 is
The depth at which the molten copper is inserted into the gap between the inner surface of and the seed line 7 becomes large.

By the way, in order to manufacture a copper-coated steel wire, M
Since a nozzle made of o-based alloy causes seizure due to sliding of the steel wire, it is necessary to use a nozzle made of ceramics. If the nozzle is made of, for example, silicon nitride ceramics, the ceramic has a remarkably lower thermal conductivity than the Mo-based alloy, so that the molten copper in the crucible is likely to be inserted between the seed wire and the inner surface of the nozzle. That is, if the thermal conductivity of the nozzle itself is high like a nozzle made of Mo-based alloy, the molten copper inserted into the gap between the inner surface of the nozzle and the seed line is immediately solidified by the heat radiation cooling effect of the nozzle and solidified metal. Is attached to the periphery of the seed wire and returns to the inside of the crucible as it travels above the seed wire, and molten copper further solidifies on the solidified metal.Therefore, the molten copper is inserted into the tapered portion of the nozzle. There is nothing to lose. However, when the inside of the housing is evacuated and a material having a low thermal conductivity such as silicon nitride-based ceramics is used for the nozzle, the heat radiation and cooling effect of the nozzle is poor, and therefore molten copper inserted between the inner surface of the nozzle and the seed wire is used. Reaches the taper part,
When the molten copper solidifies in this tapered portion, the solidified metal becomes a wedge shape along the surface of the tapered portion. If the wedge-shaped solidified metal adheres to the periphery of the seed wire and is pulled upward as the seed wire travels, the nozzle may be broken or the seed wire may be broken, and as a result, It may be impossible to continue the operation.

Further, when a ceramic nozzle is used and the inside of the housing is set to an atmosphere of an inert gas or a weak reducing gas at atmospheric pressure or higher, the molten copper in the crucible forms the inner surface of the nozzle and the seed line as described above. It is not inserted between the two, so you can operate stably for a long time,
Although it is possible to avoid causing defects such as blowholes, gas entrapment occurs between the molten copper and the seed wire at the moment when the seed wire enters the crucible, and this gas makes it difficult for heat exchange. Since the solidification amount of the molten copper is reduced, there are problems that the thickness of the coating layer becomes non-uniform, the adhesion between the coating layer and the seed wire is reduced, and the quality is reduced.

The present invention has been made in view of the above problems, and it is possible to avoid breakage of the nozzle and disconnection of the seed line due to the insertion of molten copper between the inner surface of the nozzle and the seed line, An object of the present invention is to provide a method for producing a copper-coated steel wire, which is capable of producing a copper-coated steel wire having a uniform thickness of the coating layer and good adhesion between the coating layer and the seed wire.

[0012]

A method for producing a copper-coated steel wire according to the present invention comprises: cleaning the surface of a steel wire; immersing the steel wire in molten copper held in a crucible; In the method for producing a copper-coated steel wire in which molten copper is adhered and solidified and then hot-rolled to obtain a copper-coated steel wire, from the time of cleaning the surface of the steel wire to the immersion in the molten copper The passage atmosphere of the steel wire is 160 to 600 mmHg of an inert gas or an atmosphere of weak reducing gas in absolute pressure, the ceramic nozzle having an insertion hole through which the steel wire is inserted at the bottom of the crucible is arranged, Adjust the length of the straight line of equal diameter of the insertion hole from 5 to 3
The diameter of the straight line is equal to 0 mm, and the diameter of the straight line is set to be 0.05 to 0.40 mm larger than the diameter of the steel wire.

In the present application, copper means pure copper and copper alloy.

[0014]

The present inventors have found that the pressure of the inert gas or the weak reducing gas in the housing when manufacturing the copper-coated steel wire and the shape (hole diameter and linear length) of the equal-diameter straight line portion of the ceramic nozzle. , The stability of the operation, the uniformity of the solidification amount, and the relationship between the adhesion between the coating layer and the seed wire were investigated. As a result, the following was revealed.

That is, the pressure inside the housing is made absolute.
If it is less than 160 mmHg, the hole diameter in the equal-diameter straight line portion of the insertion hole of the nozzle arranged at the bottom of the crucible is 0.05 than the diameter of the seed wire.
Even if the length of the straight line having the same diameter is 5 to 30 mm, the hot water (molten copper) can be inserted into the nozzle. If the length of the equal-diameter linear portion is set to 35 mm or the hole diameter is set to the seed wire diameter +0.04 mm to prevent insertion, the steel wire bends when passing through the equal-diameter linear portion. Due to the resistance of the nozzle, the nozzle may be damaged.
The pressure inside the housing is 160 mmHg or more in absolute pressure, and the hole diameter of the equal-diameter straight line portion is 0.05 mm or less than the diameter of the seed wire.
Up to 0.40 mm and the length of the straight part of equal diameter is 5 to 30 m
By setting m, it is possible to avoid nozzle deficiency and practically ignore the insertion of hot water into the seed wire insertion part, resulting in good uniformity of coating layer thickness and good adhesion between steel wire and coating layer. It was found that various copper-coated steel wires can be manufactured.

On the other hand, when the pressure in the housing was further increased and an attempt was made to produce a copper-coated steel wire, when the absolute pressure in the housing exceeded 600 mmHg and reached around 620 mmHg, the steel wire of the copper-coated steel wire produced There was a problem in the adhesiveness between the copper coating layer and. That is, it was found that peeling between the steel wire and the copper coating layer started to occur on the end surface when cut with the clipper. Further, it has been found that when the absolute pressure in the housing exceeds 760 mmHg (that is, when the atmospheric pressure is exceeded), the coating layer has a non-uniform thickness. The mechanism of poor adhesion and uneven coating layer thickness is involved in minute irregularities on the surface of the steel wire, which is the seed wire (unevenness due to rubbing between wires with a capstan, indentation with pinch rollers, etc.). The generated gas acts as a heat insulating material when passing through the molten copper and delays the solidification of the molten copper adhering to the periphery of the seed wire, resulting in a portion where heat is not sufficiently exchanged between the steel wire and the molten copper. ,
It is considered that the copper coating layer becomes thin or the adhesion is deteriorated at that portion. The present invention has been made based on such experimental results.

That is, in the present invention, the passage atmosphere of the steel wire (seed wire) between the cleaning of the surface and the immersion of the steel wire in the molten copper is 160 to 600 mm in absolute pressure.
In the range of Hg, and, set the hole diameter of the equal-diameter straight line portion of the insertion hole of the nozzle arranged at the bottom of the crucible by 0.05 to 0.40 mm larger than the diameter of the steel wire, and set the length of this equal-diameter straight line portion. Five
The thickness of 30 to 30 mm prevents molten copper from being inserted between the inner surface of the nozzle and the steel wire. by this,
It is possible to effectively prevent the destruction of the nozzle and the breakage of the steel wire as the seed wire due to the solidification of molten copper in the lower part of the insertion hole (tapered part), and further, the adhesion between the steel wire and the copper coating layer. It is possible to prevent defects and uneven thickness of the copper coating layer.

Although only the kind of gas in the passage atmosphere of the steel wire is arbitrary considering only avoiding the insertion of molten copper, the passage atmosphere of the steel wire is not restricted from the viewpoint of preventing oxidation of the steel wire. It is necessary to use an atmosphere of active gas or weakly reducing gas. Further, it is necessary to prevent the oxidation of the steel wire from the stage where the steel wire has been cleaned by peeling or the like. Therefore, in the present invention, the atmosphere from the cleaning of the surface of the steel wire to the seed wire insertion portion is set to the inert gas atmosphere or the weak reducing gas atmosphere having the predetermined pressure as described above.

The nozzle material is at least one selected from the group consisting of silicon carbide ceramics, silicon nitride ceramics, and zirconia ceramics because it has excellent resistance to molten copper and thermal shock resistance. It is preferable to use a ceramic material whose main component is a kind of ceramic.

[0020]

EXAMPLES Next, examples of the present invention will be described in comparison with comparative examples.

An attempt was made to manufacture a copper-coated steel wire under the following conditions using the apparatus shown in FIGS.

Example 1 A steel wire having a diameter of 12.70 mm containing 0.15% by weight of C was used as a seed wire, and a hole diameter of a straight line having an equal diameter was 12.75 mm (steel wire diameter +0.05 m).
m), using a nozzle made of silicon nitride ceramics with a length of 30 mm, the inside of the housing is filled with N ₂ gas, the absolute pressure of the housing is 160 mmHg, and the height of the molten metal in the crucible is 800 mm. While supplying the pure copper molten metal to the steel wire, the steel wire was continuously run to manufacture a copper-coated steel wire. As a result, no nozzle defect or insertion of molten copper occurred, and stable operation could be performed for a long time of more than 10 hours. Further, the uniformity of the coating layer of the copper-coated steel wire after production was good, and the adhesion between the steel wire and the copper coating layer was also good.

Example 2 The hole diameter of the straight part of equal diameter of the nozzle was 13.10 mm (steel wire diameter +0.40 m).
m) and the operation was carried out in the same manner as in Example 1 except that the length was 5 mm. As a result, similar to Example 1, stable operation could be performed for a long time exceeding 10 hours. Further, the uniformity of the coating layer of the copper-coated steel wire after production was good, and the adhesion between the steel wire and the copper coating layer was also good.

Example 3 The operation was performed under the same conditions as in Example 2 except that the pressure inside the housing was 600 mmHg in absolute pressure. As a result, similar to Examples 1 and 2, stable operation could be performed for a long time exceeding 10 hours. Further, the uniformity of the coating layer of the copper-coated steel wire after production was good, and the adhesion between the steel wire and the copper coating layer was also good.

Comparative Example 1 The diameter of the straight line portion of the nozzle is 12.75 mm (steel wire diameter +0.05 m).
m), the length was 5 mm, and the pressure inside the housing was 150 mmHg in absolute pressure, and an operation was attempted under the same conditions as in Example 1. As a result, although the nozzle was not damaged by running the steel wire during the preheating of the crucible, the molten copper was wedged along the surface of the taper part at the taper part of the nozzle due to the insertion of the hot water into the seed wire insertion hole during tapping. It solidifies, and the wedge-shaped solidified portion adheres to the periphery of the seed line and is pulled up as the seed line travels, causing breakage of the nozzle and breakage of the seed line, making it impossible to continue operation. .

Comparative Example 2 Comparative Example 1 except that the length of the straight line of equal diameter of the nozzle was 30 mm.
Attempted to operate under the same conditions as. As a result, similar to Comparative Example 1, although the nozzle was not damaged, the nozzle and the seed line were broken due to the insertion of the hot water.

Comparative Example 3 Comparative Example 1 except that the length of the straight line of equal diameter of the nozzle was 35 mm.
Attempted to operate under the same conditions as. As a result, nozzle failure occurred due to running of the steel wire during the preheating of the crucible, and the operation could not be achieved.

Comparative Example 4 The diameter of the straight line portion of the nozzle is 12.74 mm (steel wire diameter +0.04 m).
m) and an operation was attempted under the same conditions as in Comparative Example 1 except that the length was 30 mm. As a result, nozzle failure occurred due to running of the steel wire during the preheating of the crucible, and the operation could not be achieved.

Comparative Example 5 Example 1 except that the length of the equal-diameter straight line portion of the nozzle was 4 mm.
Attempted to operate under the same conditions as. As a result, similar to Comparative Example 1, although the nozzle was not damaged, the nozzle and the seed line were broken due to the insertion of the hot water.

Comparative Example 6 The hole diameter of the straight line portion of the nozzle having the same diameter is 13.15 mm (seed wire diameter +0.45 m).
An operation was attempted under the same conditions as in Example 2 except that m) was used. As a result, similar to Comparative Example 1, although the nozzle was not damaged, the nozzle and the seed line were broken due to the insertion of the hot water.

Comparative Example 7 The operation was carried out under the same conditions as in Example 1 except that the pressure in the housing was 600 mmHg in absolute pressure, and the hole diameter of the straight line portion of the equal diameter of the nozzle was 13.15 mm (seed wire diameter +0.45 mm). I tried. As a result, similar to Comparative Example 1, although the nozzle was not damaged, the nozzle and the seed line were broken due to the insertion of the hot water.

Comparative Example 8 Operation was carried out under the same conditions as in Example 1 except that the pressure inside the housing was 620 mmHg in absolute pressure. As a result, insertion was not caused when tapping hot water, stable operation was possible, and the uniformity of the copper coating layer was good. However, it was found that the adhesion between the steel wire and the copper coating layer in the copper-coated steel wire after production was not good from the cut surface with the clipper.

Comparative Example 9 Operation was carried out under the same conditions as in Example 1 except that the pressure inside the housing was 762 mmHg in absolute pressure. As a result, the nozzle was not damaged and the hot water was not inserted at the time of running the seed wire during the preheating of the crucible before the hot water was discharged, and stable operation was possible. However, the thickness of the copper coating layer was not uniform in some places, and naturally, in such a place, the adhesion between the steel wire and the copper coating layer was poor.

The absolute pressure inside the housing, the hole diameter and the length of the straight part of the equal diameter of the nozzle in these Examples and Comparative Examples are summarized in Table 1 below, and the stability and quality of operation are summarized in Table 2 below. However, the column of nozzle hole diameter in Table 1 is shown by the difference from the diameter of the seed line. In addition, in the nozzle defect column of Table 2, the case where there is no nozzle defect is ○, and the case where nozzle defect occurs is ×.
Indicated by. In addition, in the column of hot water insertion, x indicates that nozzle breakage or seed line breakage occurred due to insertion of molten copper, and o indicates when neither occurred. Further, in the column of coating uniformity, the case where the thickness of the copper coating layer is uniform is shown by ◯, and the case where the thickness is not uniform is shown by x. Further, in the column of adhesion, the case where the adhesion between the copper coating layer and the seed wire is good is indicated by ◯, and the case where the adhesion is not sufficient is indicated by x.

[0035]

[Table 1]

[0036]

[Table 2]

From Tables 1 and 2, the pressure in the housing is 160 to 600 mmHg in absolute pressure, and the diameter of the straight line portion of the seed wire insertion portion nozzle is 0.05 to 0.40 than the diameter of the seed wire.
Only when mm is large and length is 5 to 30 mm,
It can be seen that stable operation can be performed and the uniformity and adhesion of the copper coating layer are good.

In the above-mentioned embodiment, the case where pure copper is used as the molten metal and steel (carbon steel) is used as the seed wire has been explained. However, when the seed wire is Fe--Cr alloy (stainless steel), Alternatively, it is needless to say that the same effect can be obtained even when a copper alloy is used as the molten metal. Further, as the material of the nozzle, the case where the silicon nitride ceramics is used has been described in the above embodiment, but the same effect can be obtained also in the case of the silicon carbide ceramics or the zirconia ceramics. Furthermore,
In each of the above-described embodiments, the inside of the housing is made to be a nitrogen gas atmosphere, but an inert gas such as argon gas and hydrogen gas each contain 1 volume%, carbon monoxide contains 4 volume%, and the balance consists of nitrogen gas. The same effect can be obtained with a weak reducing gas.

[0039]

As described above, according to the present invention, the ceramic nozzle having the equal-diameter straight line portion of a predetermined shape is arranged at the bottom of the crucible for holding the molten copper to clean the surface of the steel wire. Since the steel wire passage atmosphere between the immersion and the immersion of the molten copper is made into an atmosphere of an inert gas of 160 to 600 mmHg or an atmosphere of weak reducing gas at absolute pressure, the copper-coated steel wire is manufactured. It is possible to produce a copper-coated steel wire having a uniform coating layer thickness and good adhesion between the coating layer and the seed wire.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a method for manufacturing a copper rough wire by a dip forming method.

FIG. 2 is a cross-sectional view showing a seed line insertion portion of a crucible.

[Explanation of symbols]

 1; crucible 2; seed wire insertion part 3; melting furnace 4; molten copper supply port 5; molten copper 6; peeling die 7; seed wire 8; capstan 9; steel coated wire 10; cooling tower 12; housing 21; Nozzle 21a; Tapered portion 21b; Equal-diameter linear portion

Claims (2)

[Claims] 1. A surface of a steel wire is cleaned, the steel wire is immersed in molten copper held in a crucible, the molten copper is adhered and solidified around the molten copper, and then hot rolling is applied to the copper coating. In the method for producing a copper-coated steel wire for obtaining a steel wire, the passage atmosphere of the steel wire between the cleaning of the surface of the steel wire and the immersion in the molten copper is 160 to 600 mmHg of inertness in absolute pressure. A gas or weak reducing gas atmosphere, a ceramic nozzle provided with an insertion hole through which the steel wire is inserted at the bottom of the crucible, and the length of the equal-diameter straight line portion of the insertion hole is 5 to 3
The method for producing a copper-coated steel wire is characterized in that the hole diameter of the straight line of equal diameter is set to 0 mm and is set to be larger than the diameter of the steel wire by 0.05 to 0.40 mm. 2. The nozzle is made of a ceramic material containing at least one ceramic selected from the group consisting of silicon carbide ceramics, silicon nitride ceramics and zirconia ceramics as a main component. 1. The method for producing a copper-coated steel wire according to 1.