TWI556888B - Copper or copper alloy continuous casting method - Google Patents

Description

Continuous casting method of copper or copper alloy

The present invention relates to a method for manufacturing a copper alloy wire used as a copper wire, a wire harness for a motor, a cable for a robot, or other signal wires, and more particularly to a continuous casting using a belt & wheel method. A method suitable for copper or copper alloys for wire use as described above.

Generally, high temperature strength and high thermal conductivity are required for the alloy used as a mold. The material of the casting ring used in the current belt method is centered on a Cu-Cr-Zr alloy or a Cu-Ag alloy of a high electrical conductivity (EC) (80 to 95% IACS) copper alloy. Since the electrical conductivity is generally proportional to the thermal conductivity, the material having a high electrical conductivity has good heat conductivity, and the ingot has excellent cooling ability and can exhibit high productivity (see Patent Document 1).

Further, in the initial stage of development of the belt casting machine, a casting ring made of iron was used to cast a pure copper alloy having a conductivity of 60% IACS or more. The electrical conductivity of the cast ring made of iron is 17% IACS. Compared with the cast ring made of copper, the thermal conductivity is small, so the cooling capacity is weak, and it is difficult to increase the casting speed. Further, cracking defects occur on the surface of the ring due to brittleness of iron, and it is impossible to perform a long-time casting operation.

Further, in general, in order to prevent sticking to the inner surface of the casting ring, the release material is applied. However, since the thermal resistance of the release material is large, if the thickness is varied, the solidification becomes uneven and ingot defects occur. In order to suppress the influence of the deviation of the mold release material, a material having a conductivity of 80% IACS or less is used for the casting ring (Patent Document 2).

Further, in the production of the Cu-Mg alloy, the temperature of the ingot is easily lowered to make the rolling load high, resulting in mechanical failure or machining cracking. Therefore, in order to lower the amount of heat removal and increase the temperature of the ingot, a casting ring having a mold conductivity of 20 to 50% IACS and having a low electrical conductivity is used (see Patent Document 3).

[Patent Document 1] JP-A-2008-173662

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-266764

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2010-188362

However, when a copper or copper alloy material is stretched to a small diameter line or an extremely thin line, sometimes a fine surface defect or an internal defect may cause a wire breakage, and thus a higher quality thick wire is required. Usually, the crack generated on the surface of the ingot cannot be crimped even if it is calendered in the subsequent step and remains. The reason for this is that an oxide film is formed on the surface of the ingot, and the solution is to add a peeling step in the middle, but the thick wire having a poor surface quality needs to increase the amount of peeling, thereby greatly reducing the yield. Further, if the shrinkage occurring inside the ingot is slight, there is no problem in the crimping step, but if the shrinkage is large, the crimping cannot be performed, especially in the case of stretching to a very thin line. Lead to the disconnection. Therefore, in order to stretch to a small diameter wire, or to achieve a high yield, or to improve the quality of the wire surface, it is necessary to make the surface and internal quality of the ingot good.

Usually, a casting ring made of a copper alloy of Cu-Ag alloy (EC: 92% IACS) or Cu-Cr-Zr alloy (EC: 80% IACS) is strongly cooled due to good heat conduction immediately after the molten metal contacts the mold. The air gap created by the solidification shrinkage of the cast skin at the beginning of solidification hinders the cooling. Therefore, the cooling after the start of solidification becomes uneven, and the thickness of the solidified shell is deviated, and cracks are generated at the weak portion. Especially in the case of casting an alloy having low electrical conductivity and poor thermal conductivity, a temperature gradient is easily generated in the solidified shell, and the cooling condition during solidification may seriously affect the quality of the ingot.

Further, when a casting ring having a low electrical conductivity is used as in Patent Document 2 or Patent Document 3 to greatly reduce the amount of heat removal, the generation of an air gap can be suppressed, but the casting ring has a high thermal resistance. Therefore, if the amount of heat removal is too small, the time period in which the solidified shell is thin and fragile becomes long, and there is a problem that solidification cracks easily occur. The fine cracks appear as surface defects when the calendering step becomes a thick drawing, which causes a serious problem such as breakage in the stretching step. Further, in order to remove the surface defect portion, peeling is performed after rolling, and thus the yield is also lowered. Further, when the amount of heat removal is small, it is easy to shrink at the center of the ingot, and when it is not possible to perform pressure bonding by rolling, the wire may be broken during the stretching step. In particular, since the alloy having poor heat conductivity is not easily cooled, the solidification is slow and the solidification crack or shrinkage easily occurs. In order to reduce the casting speed in order not to cause shrinkage, this leads to a significant decrease in productivity.

Therefore, in order to manufacture a wire having a high yield which can be stretched to an extremely fine line, it is necessary to improve the surface and internal quality of the ingot, and therefore it is extremely important to carry out casting under a cooling condition suitable for heat conduction of the alloy. In particular, alloys with poor thermal conductivity are susceptible to cooling conditions. The heat conduction of the cast alloy mentioned here means a state immediately after solidification, and for example, a precipitation type alloy means heat conduction in a solid solution state.

An object of the present invention is to provide a continuous casting method of copper or a copper alloy which is excellent in ingot quality, has high cooling ability, and is excellent in productivity.

In order to achieve the above-mentioned problems, the inventors of the present invention have produced a plurality of casting rings of various electrical conductivity, and have conducted research on the conditions of the surface, internal quality, and productivity of the ingot and the thick drawn wire, and found a casting ring having a specific electrical conductivity. The present invention has been completed based on the above knowledge findings.

That is, the present invention provides the following solutions.

(1) A continuous casting method of copper or a copper alloy, wherein a depth d (mm) of a surface defect of a copper or copper alloy thick wire manufactured by a belt method satisfies the following formula (I).

D≦r×0.1 (I)

d: depth of surface defects of thick wire (mm)

r: radius of the thick wire (mm)

(2) The continuous casting method according to (1), wherein when the copper or copper alloy is produced by the belt method, the conductivity a1 (% IACS) with respect to the cast copper or copper alloy is used to satisfy the following formula: The material of the conductivity b (% IACS) of (II-1) was used as a casting ring.

0.25×a1+15≦b<0.25×a1+35 (II-1)

A1: Conductivity of the cast copper or copper alloy (% IACS)

b: conductivity of the casting ring (% IACS)

(3) The continuous casting method according to (1) or (2), wherein, when a copper alloy having a conductivity of 60% IACS or less in a solid solution state is cast by a belt method, the copper alloy is used with respect to the cast. The conductivity a2 (% IACS) satisfies the conductivity b (% IACS) of the following formula (II-2) as a casting ring.

0.25×a2+15≦b<0.25×a2+35 (II-2)

A2: Conductivity of the cast copper alloy (% IACS)

b: conductivity of the casting ring (% IACS)

(4) The continuous casting method according to (2), wherein the above-described belt method is a casting method in which a melt in a tundish is injected from a liquid injection nozzle to a turn roll. The ingot casting machine is formed by a belt and a wheel, and is cooled and solidified to form an ingot, and the ingot is continuously extracted from the mold, and the casting ring constituting the wheel is used with respect to the cast copper or A copper alloy has a casting ring of electrical conductivity in the relationship of the above formula (II-1).

(5) The continuous casting method according to (3), wherein the above-described belt method is a casting method in which a melt in a casting distributor is injected from a liquid injection nozzle to a belt and a wheel which are rotated by a rotating roller. The ingot casting machine is cooled and solidified to form an ingot, and the ingot is continuously extracted from the casting mold, and the casting ring constituting the wheel is used in the above formula (II-2) with respect to the cast copper alloy. The relationship between the electrical conductivity of the casting ring.

According to the continuous casting method of the present invention, an ingot having an excellent surface quality and internal quality can be cast, and the productivity of a high-quality copper or copper alloy thick wire which can be stretched to a very fine line can be improved by using the ingot.

The above and other features and advantages of the present invention will be apparent from the description of the appended claims.

[Casting method, casting device]

Fig. 1 is an explanatory view showing an example of all the steps of obtaining an ingot obtained by the continuous casting method of the present invention and further forming the same into a wire. In the method for producing the copper (or copper alloy) wire, for example, as shown in FIG. 1, the molten iron is obtained by melting the barium metal or the like of the electrolytic copper in a reducing gas atmosphere using a shaft furnace 1, and the molten copper is passed through a flow guiding groove. 2 is continuously guided into the casting distributor 3. The melt 5 in the casting distributor 3 is injected from the liquid injection nozzle (outlet) 4 into the belt casting machine 8 which is formed by the belt 6 and the wheel 7 by the rotation of the rotating roller, and is cooled and solidified to form a casting. The ingot 9 continuously draws the ingot 9 from the above mold. Although not shown differently in the figure, the wheel 7 is composed of a casting ring and a wheel body. The rolling is performed by a continuous calender 10 (two-roll method or three-roll method) up to a specific wire diameter in a state where the temperature of the solidified ingot 9 is not lowered as much as possible (preferably 800 ° C or more). Pull the wire 11. The thick drawn wire 11 is directly taken up, or further rolled by the drawing calender 12 shown in Fig. 1 to form a drawn wire 13 and wound up on the pallet 14. In Fig. 1, the setting of the stretching calender 12 is arbitrary.

Next, a longitudinal sectional view of a preferred embodiment of the belt casting machine used in the belt method of the present invention is shown in Fig. 2. Figure 3 is an enlarged cross-sectional view taken along line III-III of Figure 2.

The belt casting machine for moving the casting mode has a wheel main body 21, a casting belt 22 having a cooling action by the driving roller 24, and a casting ring 23 provided on the outer circumference of the wheel main body 21. The belt 22 described above is suitable for carbon steel or stainless steel. The wheel body 21 is also suitable for carbon steel or stainless steel. The casting ring 23 is suitable for the following materials having a specific electrical conductivity. The self-injection nozzle 25 injects a molten metal (a molten copper or copper alloy, hereinafter also referred to simply as a molten metal) 26 into the casting ring 23 on the outer circumference of the wheel 21. The injected molten metal 26 is cooled in a rotationally moving casting ring and slowly solidified to form an ingot 27. Fig. 2 schematically shows the case where the melt solidifies to form an ingot. The casting speed is preferably 6 to 15 m/min (100 to 250 mm/sec or 10 to 50 t/hr) which is practically used in normal operation, and the ingot sectional area is preferably 1930 mm ² to 6450 mm ² .

[depth of surface defects]

In the method of the present invention, it is preferable that the depth of the surface defect of the copper or copper alloy thick wire manufactured by the belt method satisfies the following formula (I).

D≦r×0.1 (I)

d: depth of surface defects of thick wire (mm)

r: radius of the thick wire (mm)

By satisfying this formula, the wire breakage in the stretching step due to surface defects of the ingot or/and the thick wire can be reduced, and a wire having a high yield which can be stretched to an extremely fine line can be manufactured. The radius r of the thick wire is not particularly limited and is usually set to 2 to 12 mm. The measuring method of d is to scan the thick drawing line by the eddy current flaw detector, and calculate according to the correlation between the output of the eddy current flaw detector and the depth of the dummy defect.

If d is too large, breakage is likely to occur in the stretching step, and it is necessary to perform a large amount of peeling in order to remove the defective portion, so that productivity is remarkably lowered.

A method of manufacturing such a copper or copper alloy thick wire will be described below.

[casting ring]

(Conductivity)

A schematic representation of the relationship between the electrical conductivity of the casting ring and the heat removal from the ingot is shown in Figures 5-7. The case where the conductivity of the casting ring is high is shown in Fig. 5, and the lower case is shown in Fig. 6, and the situation within the scope of the present invention is shown in Fig. 7. The larger the arrow, the faster the heat removal rate. Continuous casting using the previous belt method is overwhelmingly faster than the well-known DC casting or horizontal transverse continuous casting method, so the solid-liquid coexistence region exists longer in the casting direction, while in copper or In the copper alloy, the deviation of the thickness of the solidified shell is also likely to occur at the final solidified portion. Further, it is known that a casting ring of high conductivity is strongly cooled due to good heat conduction immediately after the melt contacts the ring, thereby causing an air gap caused by immediate solidification shrinkage, which hinders cooling, so that cooling does not become. Uniform, the thickness of the solidified shell is not fixed. In particular, alloys with poor thermal conductivity are more likely to produce a temperature distribution within the solidified shell than copper or copper alloys with good thermal conductivity, resulting in localized stress concentrations due to uneven thickness of the solidified shell or solidification shrinkage and heat shrinkage. Solidification cracks are generated on the surface of the ingot.

Further, when the conductivity of the casting ring is too low, the generation of the air gap can be suppressed, but since the casting ring becomes a thermal resistance, the overall cooling ability is lowered. Therefore, the growth period of the solidified shell is delayed, and the period in which the shell strength is weak is lengthened, so that solidification cracks are likely to occur. Further, if the solidification is delayed so that the final solidified portion approaches the height of the liquid injection portion, the effect of the riser becomes weak and shrinkage occurs. Alloys with poor thermal conductivity are particularly difficult to cool and therefore have a more pronounced adverse effect. For these reasons, the surface and internal defects of the ingot are generated, which become defects of the thick wire and cause breakage during stretching.

Therefore, the inventors investigated the relationship between the electrical conductivity of the treated copper or copper alloy and the electrical conductivity of the cast ring in order to study the cooling conditions for achieving the growth of the solidified shell under stable conditions.

The results of studies using various pure copper or copper alloys having different electrical conductivity are as follows. The conductivity of the casting ring (% IACS) is preferably set to the following (II-1) depending on whether the foundry is pure copper or a copper alloy. The formula or the range of the following formula (II-2). This relationship is shown in Fig. 4.

0.25×a1+15≦b<0.25×a1+35 (II-1)

A1: Conductivity of the cast copper or copper alloy (% IACS)

b: conductivity of the casting ring (% IACS)

0.25×a2+15≦b<0.25×a2+35 (II-2)

A2: Conductivity of the cast copper alloy (% IACS)

b: conductivity of the casting ring (% IACS)

That is, in the preferred embodiment of the present invention, the formation of the air gap immediately after the liquid injection can be extremely effectively suppressed by using a casting ring made of a copper alloy having a specific conductivity. Therefore, the heat transfer due to the air gap at the initial stage of solidification is moderated, and stable cooling can be performed. As a result, a stable solidified shell having uniform properties without a weak portion can be formed. By suppressing the air gap and further cooling it with a casting ring having a conductivity of a certain value or more, a sufficient cooling rate can be obtained, and shrinkage can be prevented. Further, since the supercooling is changed, the nucleation frequency is increased, and the ingot structure near the surface of the ingot can be made fine. The surface quality of the ingot can be improved by these effects, and the crack on the surface of the ingot can be suppressed. Further, by improving the quality of the ingot, the surface defects of the thick wire can be suppressed, and the quality and yield of the thick wire can be improved.

The heat transfer between the ingot and the casting ring can also be changed according to the amount of the release material applied to the surface of the ring, but it is difficult to perform fine control and is not suitable for stable operation, and can be controlled by the conductivity of the casting ring. Simpler and more stable casting.

In the above formula (II-1) or (II-2), the cooling efficiency can be sufficiently ensured by setting it to the above lower limit value, and the inside and the surface quality of the ingot can be improved, which is preferable. It is preferable to maintain the quality of the surface of the ingot by setting it as the said upper limit or less. Further, in the present invention, the conductivity is a value measured by the measurement method employed in the examples unless otherwise specified.

Particularly in the case of producing an alloy having poor heat conductivity and low electrical conductivity, the effect of the method of the present invention is remarkable since the cooling conditions have a serious influence on the quality.

(alloy)

In consideration of the above aspects, as the alloy material constituting the casting ring, Cu-Cr-Zr-Al alloy, Cu-Cr alloy, Cu-Be alloy, phosphor bronze, Carson alloy, Cu-Zn alloy are preferable. Copper alloy such as Cu-Ni-Sn alloy. The representative composition of each of the copper alloys is preferably described below.

‧Cu-Cr(-Zr-Al) alloy

Cr: 0.2% by mass to 2.0% by mass (preferably 0.3% by mass to 1.5% by mass, more preferably 0.5% by mass to 1.5% by mass)

Zr: 0% by mass to 0.5% by mass (preferably 0.08% by mass to 0.30% by mass)

Al: 0% by mass to 3.0% by mass (preferably 0.3% by mass to 2.0% by mass)

The remainder is copper and inevitable impurities

‧Cu-Be alloy

Be: 0.3% by mass to 3.0% by mass (preferably 0.5% by mass to 2.0% by mass)

Co: 0.1% by mass to 1.0% by mass (preferably 0.2% by mass to 0.6% by mass)

The remainder is copper and inevitable impurities

‧phosphor bronze

Sn: 1% by mass to 8% by mass (preferably 1% by mass to 6% by mass)

P: 0.03 mass% to 0.4 mass% (preferably 0.03 mass% to 0.1 mass%)

The remainder is copper and inevitable impurities

Carson alloy

Ni: 1% by mass to 5% by mass (preferably 1.1% by mass to 5% by mass)

Si: 0.2% by mass to 1.3% by mass (preferably 0.3% by mass to 1.3% by mass)

The remainder is copper and inevitable impurities

‧Cu-Zn alloy

Zn: 10% by mass to 50% by mass (preferably 20% by mass to 45% by mass)

The remainder is copper and inevitable impurities

‧Cu-Ni-Sn alloy

Ni: 0.1% by mass to 5% by mass (preferably 1% by mass to 2% by mass)

Sn: 0.1% by mass to 1% by mass (preferably 0.3% by mass to 0.5% by mass)

The remainder is copper and inevitable impurities

[The pure copper material cast]

In view of the characteristics of the above-described belt method and the phenomenon at the time of casting, it is preferred to cast a pure copper such as refined copper or oxygen-free copper as described below in the casting method using the casting ring of the present invention.

‧ Silver-containing copper or oxygen-free copper

Ag: 0.03 to 0.20% by mass

‧ tin-containing or copper-free copper

Sn: 0.05 to 0.70% by mass

[The cast copper alloy]

In consideration of the characteristics of the above-described belt method and the phenomenon at the time of casting, in the casting method using the casting ring of the present invention, it is preferable to cast a copper alloy having the following composition, which is particularly effective.

‧Cu-Sn alloy

Sn: 0.2% by mass to 8% by mass

The remainder is copper and inevitable impurities

Carson alloy

Ni: 1.0% by mass to 5.0% by mass

Si: 0.2% by mass to 1.3% by mass

The remainder is copper and inevitable impurities

‧Cu-Cr alloy

Cr: 0.1% by mass to 1.5% by mass

The remainder is copper and inevitable impurities

‧Cu-Cr-Zr alloy

Cr: 0.1% by mass to 1.5% by mass

Zr: 0.01% by mass to 0.5% by mass

The remaining part of copper and the inevitable impurities

‧Cu-Cr-Sn alloy

Cr: 0.1% by mass to 1.5% by mass

Sn: 0.01% by mass to 0.5% by mass

The remainder is copper and inevitable impurities

‧Cu-Zr alloy

Zr: 0.01% by mass to 2.0% by mass

The remainder is copper and inevitable impurities

‧Cu-Fe-P alloy

Fe: 0.1% by mass to 1.5% by mass

P: 0.01% by mass to 0.5% by mass

The remainder is copper and inevitable impurities

‧Cu-Ni-Sn alloy

Ni: 0.2% by mass to 2.5% by mass

Sn: 0.01% by mass to 1.0% by mass

The remainder is copper and inevitable impurities

[Examples]

Hereinafter, the present invention will be described in further detail based on examples, and examples thereof, such as samples and their production conditions, are merely specific examples, and the present invention is not limited thereto. In addition, in the following description, unless otherwise indicated, the % of composition shows the mass %.

[Example 1]

As shown in Tables 1 to 9, a casting ring having an ingot having a cross-sectional area of 3220 mm ² having an electric conductivity of 15 to 80% IACS was used. The component compositions of the alloy materials constituting the casting ring are collectively described at the end of the following examples and comparative examples. A fine copper (TPC) containing 0.03% Ag (see Table 1) of Φ8 mm, a refined copper containing 0.15% of Sn (refer to Table 2), and refined copper containing 0.3% Sn were produced by the SCR method at a casting speed of 20 ton / hr. (Refer to Table 3), refined copper containing 0.7% Sn (refer to Table 4), Cu-0.3%Cr-0.3%Sn (refer to Table 5), Cu-0.5%Cr alloy (refer to Table 6), Cu-1.5% Ni-1.0%Sn (refer to Table 7), Cu-2.5%Ni-0.6%Si Carson alloy (refer to Table 8) and Cu-1.0%Fe-0.3%P (refer to Table 9) copper or copper alloy Wire and stretch to Φ0.1 mm. According to the detection result of the eddy current flaw detector when manufacturing the thick wire, and the observation of the stomatal nest amount when the longitudinal section of the ingot is observed, and whether the product is stretched after the peeling of the thick wire, the product is judged to be good or bad, and the result is shown. In Tables 1-9.

[Measurement of Conductivity]

The conductivity of the casting ring was measured using a AutoSigma 3000 (trade name) manufactured by GE Inspection Technologies, Inc., to measure the polished surface of the casting ring.

For the detection results of the eddy current flaw detector shown in Tables 1 to 9, the small defect satisfying the above formula (I) is set to "s", and the large defect that does not satisfy the formula (I) is set to "1", and the count is for each One ton detected the number of each. Further, the deepest (maximum defect depth) of the surface defects detected and measured was defined as the surface defect depth d (mm).

The center porosity is taken from the ingot of the length of 1 m, and the longitudinal section of the central portion is observed, and the extension length of the pore nest having a width of 0.5 mm or more is measured. In addition, the determination of the amount of peeling and the disconnection is based on the Φ8 mm thick pull line 5000 kg as shown on the one side peeled with a thickness of 0 to 0.2 mm and stretched to Φ 0.1 mm, and the disconnector is evaluated as " × (not available), and the unbroken person is evaluated as "○ (may)".

In the "Evaluation" in the rightmost column of Tables 1 to 9, when the one-side peeling is 0 mm, the unbroken one is evaluated as "◎ (excellent)", and the one-side peeling is 0 mm. When the one-side peeling is 0.1 mm, the unbroken one is evaluated as "○ (good)", and the one-side peeling is 0.1 mm when the thread is broken, and the one-side peeling is 0.2 mm when the thread is not broken. The evaluation was "△ (may)", and when the one side was peeled to 0.2 mm, the disconnected person was evaluated as "x (not)".

Table 10 shows the electrical conductivity of each copper or copper alloy and the lower limit and upper limit of the electrical conductivity of the mold defined by the following formula (II). The conductivity of the copper or copper alloy cast here refers to the conductivity in a solid solution state. The formula (II) is a combination of the above formula (II-1) and the formula (II-2), and is equivalent thereto.

0.25×a+15≦b<0.25×a+35(II)

a: Conductivity of cast copper or copper alloy (% IACS)

b: conductivity of the casting ring (% IACS)

Any of the alloys has the following results: when the casting ring satisfying the condition of the formula (II) (i.e., the formula (II-1) and the formula (II-2)) is used, the maximum defect depth satisfies the formula (I), and the flaw detection result is broken. The line judgment is excellent. Further, when a casting ring having a conductivity not lower than the lower limit is used, the cooling ability is insufficient, so that the supply of the melt to the center portion of the ingot is insufficient, which causes a large shrinkage and causes a disconnection failure. It is known that a casting ring having a conductivity not exceeding the upper limit is preferable because it is possible to prevent deterioration of the surface quality of fine cracks on the surface of the ingot as described above. Further, it is known that, in the case where the region of the formula (II) is not satisfied, the alloy having a conductivity of the cast alloy higher than 60% IACS can be avoided by peeling if the conductivity of the cast ring is not extremely low. The wire is broken, but the alloy below 60% IACS is broken even if it is peeled 0.2 mm on one side. The present invention is particularly effective for alloys having a casting alloy conductivity of 60% IACS or less.

[Example-2]

An embodiment when changing the casting speed.

Carson alloy of Cu-2.5% Ni-0.6% Si ingot to the sectional area of 3220 mm ^2, having the conductivity of the various tables shown in casting ring 11 (the mold), the casting speed is changed, except that with the embodiment Casting was carried out in the same manner as in Example 1.

The casting speed V, which is the relative speed, was evaluated by using a casting ring of 80% IACS based on the usual casting speed V ₀ (200 mm/sec). Vr=V/V ₀ .

When the casting speed is too fast with respect to the cooling rate, the ingot temperature is excessively high, and the strength of the ingot is lowered to cause cracks, or the center portion of the ingot remains large and shrinks. Therefore, the judgment of the result of the implementation is that the Φ8 mm thick wire 5000 kg is peeled 0.1 mm on one side and the unbroken one is evaluated as "○ (可)", and the wire breaker is evaluated as "× (not available).

The results are shown in Table 11.

Judging the broken wire when Φ8 mm thick wire 5000 kg is peeled 0.1 mm and stretched to Φ0.1 mm

○: no disconnection

×: There is a broken line

The casting ring having the conductivity of the range specified by the present invention can suppress the generation of the air gap, so that it can be cooled more effectively than the high-conductivity casting ring in the initial stage of solidification, and since the electrical conductivity is higher than that of the iron casting ring, The overall cooling capacity can be made higher than the high conductivity ring. The casting speed can be increased by a factor of 1.2 in the region satisfying the formula (II) (i.e., the formulae (II-1) and (II-2)) in the experiment using the casting rings of various conductivity.

[Example 3]

Casting, rolling, and drawing were performed in the same manner as in Example 1 using various casting rings having different electrical conductivity for various copper or copper alloys. The crystal grain size (μm) of the ingot was measured by the intersection method in a direction perpendicular to the grain growth direction at a position of 2 mm from the surface of the ingot. Further, evaluation was carried out in the same manner as in Example 1. Further, the upper limit of the formula (II) of the casting ring (i.e., the formula (II-1) and the formula (II-2)) is 60% IACS, and the lower limit is 16% IACS.

The results obtained are shown in Table 12.

It is understood that, compared with the comparative example in which the conductivity is too high, by using the casting ring having the conductivity of the range of the present invention, the supercooling in the vicinity of the mold becomes large and the nucleation frequency becomes high, so that the surface of the ingot can be made. The ingot structure in the vicinity is refined to improve the surface quality of the ingot. As a result, surface defects can be alleviated, and even if there is less peeling, no breakage occurs, and stretching can be performed.

The composition of the casting ring of each conductivity used is shown in Table 13.

The present invention is not limited to the details of the present invention, and is not intended to limit the scope of the present invention. The scope of the invention should be interpreted to the fullest extent.

The present invention is based on the priority of Japanese Patent Application No. 2011-003452, filed on Jan.

1‧‧‧ shaft furnace

2‧‧‧Rough

3‧‧‧ casting dispenser

4‧‧‧Exit

5, 26‧‧‧ melt

6, 22 ‧ ‧ belt

7, 21‧‧ round

8‧‧‧Roller casting machine

9, 27‧‧‧ ingots

10‧‧‧Continuous calender

11‧‧‧Cut wire

12‧‧‧ stretching calender

13‧‧‧Stretched material

14‧‧‧Board

23‧‧‧ casting ring

24‧‧‧Drive roller

25‧‧‧Injection nozzle

Fig. 1 is a schematic explanatory view showing a step of manufacturing a wire in an embodiment of a continuous casting method using the belt method of the present invention.

Fig. 2 is a cross-sectional view schematically showing a preferred embodiment of a belt casting machine used in the continuous casting method of the present invention.

Fig. 3 is an enlarged cross-sectional view showing a section III-III of the casting machine shown in Fig. 2.

Figure 4 is a graph showing the relationship between the electrical conductivity of the cast alloy and the electrical conductivity of the cast ring.

Fig. 5 is an explanatory view schematically showing heat removal in the case where the conductivity of the casting ring is high.

Fig. 6 is an explanatory view schematically showing heat removal in the case where the conductivity of the casting ring is low.

Fig. 7 is an explanatory view schematically showing heat removal when the conductivity of the casting ring is within the range of the present invention.

twenty one. . . wheel

twenty two. . . band

twenty three. . . Casting ring

twenty four. . . Drive roller

25. . . Injection nozzle

26. . . Melt

27. . . Ingot

Claims (2)

A continuous casting method of copper or copper alloy, the depth d (mm) of surface defects of a copper or copper alloy thick wire manufactured by a belt & wheel method satisfies the following formula (I), and When a copper alloy having a conductivity of 60% IACS or less in a solid solution state is cast by a belt method, conductivity (b) satisfying the following formula (II-2) with respect to the conductivity a2 (% IACS) of the cast copper alloy is used ( %IACS) material as casting ring, d≦r×0.1 (I)d: depth of surface defect of thick wire (mm) r: radius of thick wire (mm) 0.25×a2+15≦b<0.25×a2 +35 (II-2) a2: Conductivity of the cast copper alloy (% IACS) b: Conductivity of the cast ring (% IACS). The continuous casting method according to claim 1, wherein the wheel method is a casting method in which a molten metal in a tundish is injected from a liquid injection nozzle to a turn by a turn roll. The ingot is formed by a belt and a wheel, and is cooled and solidified to form an ingot, and the ingot is continuously withdrawn from the mold, and the casting ring constituting the wheel is used with respect to the cast copper alloy. The casting ring of the conductivity of the relationship of the formula (II-2).