JP2010198873A - Conductor for electric wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductor for an electric wire, excellent in toughness while having high strength; and to provide an electric wire equipped with the conductor. <P>SOLUTION: The conductor for an electric wire comprises wires of a copper alloy. The copper alloy contains, by mass ratio, 2-6% of Sn, 10-300 ppm of P, and 1-50 ppm or less of oxygen, and the balance comprises Cu and impurities. The content of the impurity is, by mass ratio, a total of 200 ppm or less. The conductor utilizes oxygen-free copper as a raw material, and is manufactured being subjected to softening treatment after wire drawing. By the softening treatment, the conductor has excellent toughness and an elongation of 10% or more. Although an amount of Sn in the conductor is relatively small, concentrations of oxygen and the impurities are low, so that the conductor has high strength. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a conductor for electric wires made of a Cu-Sn alloy and an electric wire including the conductor. In particular, the present invention relates to a conductor for electric wires having excellent toughness.

  Conventionally, conductors made of copper-based materials such as pure copper and copper alloys having excellent conductivity have been mainstream. Patent Documents 1 and 2 disclose a conductor made of a Cu—Sn alloy.

JP 04-017214 A JP 05-266719 A

  In recent years, it has been desired that a conductor for electric wires be provided with a better balance between strength and toughness (e.g., elongation) while maintaining a predetermined conductivity.

  In Cu—Sn alloys as described in Patent Documents 1 and 2, the strength tends to increase as the Sn content increases. However, since an increase in Sn causes a decrease in conductivity, there is a limit to an increase in Sn in consideration of the conductivity.

  Further, in the case of a conductor having high strength and low toughness, for example, a terminal may be attached to the end of an electric wire, and the conductor may break near the boundary with the terminal due to an impact when the terminal is assembled to a device or the like. .

  Further, the conductor structure includes a single wire structure composed of a single wire, a stranded wire obtained by twisting a plurality of wires (element wires), and a compressed stranded wire obtained by compressing the stranded wire. If the toughness of the strand itself is high, it is easy to perform twisting, and even if it becomes a stranded wire or a compression stranded wire, it is easy to maintain high toughness, and it can be a conductor excellent in toughness.

  Therefore, an object of the present invention is to provide a conductor for electric wires that is high in strength and excellent in toughness, and an electric wire including the conductor.

  The present inventors have obtained the knowledge that a copper alloy wire having high strength and excellent toughness can be obtained by applying a specific heat treatment after wire drawing by using a copper alloy having a specific composition. The present invention is based on this finding.

  The conductor for electric wires of the present invention is a conductor composed of a copper alloy wire. The above copper alloy contains Sn in a mass ratio of 2% to 6%, P in a range of 10 ppm to less than 300 ppm, oxygen in a range of 1 ppm to 50 ppm, and the balance consisting of Cu and impurities. The content of the impurities is 200 ppm or less in total by mass ratio. The electric wire of the present invention includes the above-described conductor of the present invention and an insulating layer provided on the outer periphery of the conductor.

  The conductor of the present invention is composed of a specific composition that does not contain excessive Sn and has a low oxygen concentration and impurity concentration, so that it has high strength even if the Sn content is relatively small, and has a large elongation. Excellent toughness. Therefore, the electric wire of the present invention including the conductor of the present invention is excellent in impact resistance and can sufficiently have the strength desired for the electric wire. In addition, since the wire constituting the conductor of the present invention is excellent in toughness, for example, even when a plurality of this wire is twisted to form a stranded wire, or when this stranded wire is compressed into a compression stranded wire, It is expected to be an excellent conductor. Furthermore, although the conductor of the present invention has a lower electrical conductivity than pure copper, for example, it has sufficient electrical conductivity desired for a signal line having a relatively small current value. be able to. Hereinafter, the present invention will be described in more detail. In addition, content, such as an element in a copper alloy, shows a mass ratio.

[conductor]
"composition"
The copper alloy constituting the conductor of the present invention is a Cu—Sn alloy whose main additive element is Sn. By containing 2% or more of Sn, a wire having excellent strength is obtained. As the Sn content is higher, the strength and toughness tend to increase, but the conductivity tends to decrease. Further, with the increase of Sn, tin oxide is easily generated. With this tin oxide, disconnection is likely to occur particularly during wire drawing, and it becomes difficult to continuously produce a long and thin wire rod. Therefore, the upper limit of Sn is 6%. A more preferable content of Sn is 2.5% or more and 4% or less. In particular, when the conductor has a small diameter such as a cross-sectional area of 0.2 mm ² (equivalent to 0.2 sq) or less, the strength can be further improved if the Sn content is 3% or more.

  Since the copper alloy has a low oxygen concentration of 50 ppm or less, the strength can be increased even if the Sn content is relatively low, such as 6% or less. If the oxygen concentration is to be less than 1 ppm, deoxidation treatment requires a lot of cost and labor, but the oxygen concentration is less than 1 ppm compared to 1 to 50 ppm. Since the effect of improving the strength by is not so great, the lower limit of the oxygen concentration was set to 1 ppm. If the oxygen concentration exceeds 50 ppm, the strength is reduced. Also, if the oxygen content exceeds 50 ppm, long thin wire rods can be obtained due to surface defects caused by blowholes produced during casting and the presence of tin oxide produced during production, particularly during wire drawing. It becomes difficult. In order to manufacture such a wire made of a copper alloy having a low oxygen concentration, oxygen-free copper (purity is 99.995 mass% or more and oxygen concentration (mass ratio): 10 ppm or less) is used as a raw material. Or a material having a low oxygen content, for example, a mold or crucible made of carbon, or a non-oxidizing atmosphere during heat treatment. A more preferable oxygen concentration is 1 ppm or more and 10 ppm or less.

  P (phosphorus) in the copper alloy functions as a deoxidizer, and by containing P at 10 ppm or more, the concentration of oxygen can be lowered as described above. The higher the content of P, the higher the deoxidation effect, but the lower the conductivity as P increases. In consideration of conductivity, the upper limit of P is set to less than 300 ppm. A more preferable content of P is 50 ppm or more and 200 ppm or less.

  The copper alloy has a very low content of impurities, and is a total of 200 ppm or less. By suppressing the impurities within this range and reducing the oxygen concentration as described above, it is possible to reduce a decrease in strength due to the precipitation of the oxide and to reduce disconnection due to the oxide (particularly during wire drawing). The impurity is more preferably 150 ppm or less, and a smaller amount is preferable, and therefore no lower limit is particularly set. In order to bring the impurities into the above range, it is possible to use high-purity raw materials or to dissolve them using a furnace body (crucible) that does not contain a large amount of metal elements to reduce the dissolution of impurities into copper.

  The copper alloy may further contain 0.05% or more and 0.3% or less of Ni. By containing Ni in this range, the strength can be further improved without significantly reducing the electrical conductivity.

"shape"
The wire constituting the conductor of the present invention can have various diameters (wire diameters) by appropriately adjusting the degree of processing during wire drawing. For example, a wire having a diameter of 0.1 mm or more and 0.5 mm or less is suitably used in a field in which a small diameter is desired, for example, a conveyance device such as an automobile or an airplane, various electronic components, and a conductor of an electric wire for an industrial robot. be able to.

  The wire can have various cross-sectional shapes depending on the shape of a die during wire drawing. A cross-sectional circular shape is typical, and other cross-sectional shapes such as an elliptical shape, a polygonal shape such as a rectangle or a hexagon are listed. The shape is not particularly limited.

The conductor of the present invention may have a single wire structure composed of one wire, or a twisted wire structure in which a plurality of the wires are twisted together. Even a thin wire rod can be made into a high strength wire rod (twisted wire) by twisting together. The number of twists is not particularly limited. For example, 7,11,19,37 are mentioned. In addition, the conductor of the present invention can be subjected to compression processing after being twisted to form a compression stranded wire. By setting it as a compression twisted wire, a wire diameter can be made smaller than the twisted state. Compressed stranded wire is obtained by, for example, twisting a plurality of wires each having a diameter of 0.1 mm or more and 0.5 mm or less, and subjecting the obtained stranded wire to compression processing with a compression ratio of 20% or less. In addition, the cross-sectional area of the compression stranded wire is 0.05 mm ² or more and 0.3 mm ² or less. The compression ratio is obtained by compression ratio = 1 − {(cross-sectional area of the stranded wire after compression) / (cross-sectional area of the stranded wire before compression)}.

"Characteristic"
The conductor of the present invention is composed of a soft material obtained by performing a specific heat treatment (softening treatment) to be described later on a wire material, a stranded wire, or a compression stranded wire composed of the Cu-Sn alloy having the specific composition described above. Excellent and elongation is 10% or more. In addition, the conductor of the present invention has high strength by being composed of the Cu—Sn alloy having the above specific composition, and has a tensile strength of 330 MPa or more. Further, the conductor of the present invention is composed of the Cu—Sn alloy having the above specific composition, so that the electrical conductivity is high and is 20% IACS or more. Depending on Sn, P, oxygen content, softening conditions, wire diameter, etc., the conductor of the present invention can satisfy elongation of 30% or more and tensile strength of 360 MPa or more.

  By appropriately adjusting Sn, P, oxygen content, manufacturing conditions (working degree during wire drawing (cross-sectional reduction rate), softening conditions, etc.), conductivity, elongation, and tensile strength satisfy the above specified ranges. Wire material etc. are obtained. Increasing Sn or decreasing oxygen tends to increase strength, and decreasing Sn or P or increasing temperature during softening tends to increase toughness and electrical conductivity. .

[Electrical wire]
The above-mentioned conductor of the present invention can be used as a conductor as it is depending on the application, or can be used as an electric wire having an insulating layer formed of an insulating material on the outer periphery of the conductor. The insulating material can be selected as appropriate. For example, polyvinyl chloride (PVC), a non-halogen resin, a material excellent in flame retardancy, and the like can be given. The thickness of the insulating layer can be appropriately selected in consideration of desired insulating strength, and is not particularly limited. A terminal can be attached to the end portion of the electric wire so that it can be connected to a connection target such as a device, thereby forming an electric wire with a terminal. It can also be set as the electric wire group which shares one terminal part with respect to a some electric wire. In this case, it is excellent in the handleability of an electric wire group by bundling a some electric wire in a lump with a binding tool.

[Production method]
The conductor of the present invention can be typically formed by a process of casting → drawing → final heat treatment (softening treatment). Moreover, this invention electric wire can be formed by providing an insulating layer in the outer periphery of the said this invention conductor.

  The casting may be billet casting, but continuous casting is preferred in which a cast material having a microstructure is obtained by refining crystal grains and crystal precipitates by rapid solidification. In continuous casting, it is more desirable to use a horizontal casting machine or a vertical casting machine that can obtain a cooling rate of 10 ° C./sec or more during solidification. When the cooling rate is 10 ° C./sec or more, crystal grains can be refined and crystal precipitates can be finely dispersed. By continuous casting, it is possible to improve strength by refining crystals and toughness by dispersing fine crystal precipitates. In particular, it is preferable to use a material having a low oxygen content, for example, a material made of high-purity carbon, for the mold and the crucible.

  In the wire drawing step, the degree of processing can be appropriately selected according to the desired wire diameter. When an intermediate heat treatment is appropriately performed in the middle of wire drawing, the workability at the time of the next wire drawing can be improved, and the tensile strength of the wire (soft material) after softening at the final wire diameter can be increased. The intermediate heat treatment is preferably performed at a heating temperature of 400 ° C. to 500 ° C. and a heating time of 0.5 hour to 5 hours. Also, the degree of wire drawing from the intermediate heat treatment to the final wire diameter (-ln (A / A0), or ln (A0 / A), A: cross-sectional area of the wire at the final wire diameter, A0: final wire diameter By setting the cross-sectional area of the wire after the intermediate heat treatment performed immediately before to 2.0 to 9.0, the tensile strength of the wire after softening at the final wire diameter can be further increased. The drawing degree is more preferably 5.0 or more and 8.0 or less. Furthermore, it is preferable to remove the surface defects and the oxide film by appropriately peeling in the middle of wire drawing because a wire having excellent surface properties can be obtained. As for the obtained wire drawing material, a desired number can be prepared and twisted together to form a stranded wire, or the stranded wire can be compressed to form a compressed stranded wire.

  The softening treatment is performed in order to increase the toughness of the wire by softening without extremely reducing the strength of the wire that has been increased by refinement of the crystal structure and work hardening. The conditions for the softening treatment may be appropriately selected, and both batch treatment and continuous treatment can be applied. The batch process is a process of heating in a state where a heating target is enclosed in a heating container (atmosphere furnace, for example, a box furnace), and tends to obtain a wire having a higher elongation than the continuous process. The continuous treatment includes a method using resistance heating, a method using high-frequency electromagnetic induction, a method using a heating vessel (pipe softening furnace) in a heating atmosphere, and the like, and is suitable for mass production. In the case of batch treatment, the heating temperature is preferably 400 ° C. or more and 500 ° C. or less, and the heating time is preferably 3 hours or more and 5 hours or less, and in the case of continuous treatment, the elongation of the treated wire (single wire, stranded wire, compression stranded wire) is 10 %.

The atmosphere of the intermediate heat treatment and softening treatment is preferably a non-oxidizing atmosphere in order to suppress the formation of an oxide film on the surface of the wire due to heat during the treatment. Non-oxidizing atmospheres include, for example, a vacuum atmosphere (reduced pressure atmosphere), an inert gas atmosphere such as nitrogen (N ₂ ) and argon (Ar), a hydrogen-containing gas (for example, hydrogen (H ₂ ) only, N ₂ , Ar, Reducing properties such as inert gas such as helium (He) and hydrogen (H ₂ ) and carbon dioxide containing gas (for example, mixed gas of carbon monoxide (CO) and carbon dioxide (CO ₂ )) A gas atmosphere is mentioned.

  In the above-mentioned stranded wire and compression stranded wire, softening treatment may be performed only on the wire material before twisting, softening treatment may be performed on both before and after twisting, or not applied to the wire drawing material before twisting, You may perform a softening process only to a twisted wire or a compression twisted wire. Even when only the wire before twisting is softened, this wire (soft material) is excellent in toughness.Therefore, even if the twisted wire after compression and the compression twisted wire are not softened, high toughness is achieved. It is expected that you can have.

  The conductor for electric wire of the present invention and the electric wire of the present invention are excellent in toughness while having high strength.

  Wires made of Cu-Sn alloy were prepared and their characteristics were evaluated.

<Example>
Samples are prepared in the order of preparation of raw materials → production of molten alloy (melting) → continuous casting → cold working (rolling) → cold drawing (→ intermediate heat treatment) → twisting and compression → final heat treatment (softening treatment) did. More specifically, oxygen-free copper is prepared as a raw material, dissolved in the atmosphere in a high-purity carbon crucible of a horizontal continuous casting machine (1150 to 1250 ° C.), completely melted, and then the crucible of the continuous casting machine. The tin particles and phosphorus prepared inside were added and further dissolved. The molten Cu—Sn mixed melt was cast by a horizontal continuous casting machine (mold: made of high-purity carbon) to produce a cast material (wire material having a diameter of 22 mm). The cooling rate during solidification at this time was 10 ° C./sec or more. The addition amounts of tin grains and phosphorus were adjusted so as to have the composition shown in Table 1.

The obtained cast material was cold-rolled, processed into a wire having a diameter of 9.5 mm, and then heat-treated (450 ° C. × 3 hours, non-oxidizing atmosphere). The heat treatment material was skinned to remove the surface layer, and a wire with a diameter of 8 mm was obtained. The obtained wire was subjected to multiple passes of cold drawing to finally obtain a round wire having a diameter of 0.2 mm or 0.175 mm. Further, when forming a round wire having a wire diameter of 0.175 mm, an intermediate heat treatment (480 ° C. × 4 hours) was appropriately performed during the drawing process. The drawing degree (-ln (A / A0)) from the intermediate heat treatment to the final wire diameter was adjusted to 2.0-9.0. The obtained round wire is used as a strand, and seven strands are twisted to produce a stranded wire. The stranded wire is subjected to compression processing with a compressibility of 10%, and the cross-sectional area shown in Table 1 (mm ² ) was obtained compressed stranded wire having a (cross-sectional area: 0.22 mm ² diameter 0.2mm round wire used, the cross-sectional area: 0.13 mm round wire using the ^second diameter 0.175 mm). The obtained compression twisted wire was subjected to softening treatment (480 ° C x 3 hours, batch treatment) as a sample (Sample No. 1 to 3), and for each sample, breaking load, elongation, impact value, electrical resistivity Was measured. The results are shown in Table 1.

  In addition, samples obtained by subjecting the obtained 0.2 mm round wire to heat treatment (500 ° C x 2 hours) were used as samples. For each sample, tensile strength, 0.2% proof stress, elongation, conductivity, oxygen concentration, impurity content The amount was measured. The results are shown in Table 1.

  Tensile strength (MPa), 0.2% proof stress (MPa), elongation (%), and breaking load (N) were measured in accordance with JIS Z 2241. More specifically, a test sample is prepared, a grip test is performed at 250 mm / min, a tensile speed is 50 mm / min, and a tensile test is performed until the test sample breaks. The maximum load value at the time of the tensile test divided by the area of the cross section of the test sample is taken as the tensile strength, and the maximum load value is taken as the breaking load. Further, after the test sample is broken, the grip portion is removed and the grip interval is measured, and the value calculated by elongation = 1 − {(the grip interval after the break) / (the grip interval before the test)} is taken as the stretch. The electrical resistivity (mΩ / m) was measured by the 4-terminal method. The oxygen concentration and impurity content (both ppm by mass ratio) were examined using an ICP emission spectroscopic analyzer. The impurities were at least one element of Fe, Pb, Bi, Ag, Sb, As, Zn, Si, and Al.

The impact value (Nm) is the maximum at which one end of the sample (distance between the gauge points: 1 m) is fixed, a weight is attached to the other end, the weight is lifted upward by 1 m, then dropped freely, and the sample does not break. measuring the weight of the weight (kg), and the product value obtained by multiplying a falling distance 1m between the gravitational acceleration (9.8m / s ²⁾ to the weight.

<Comparative example>
As a comparative sample, Sample No. 100 made of pure copper was prepared as follows. Prepare oxygen-free copper, produce a pure copper casting by the horizontal continuous casting machine, and cold-roll → heat treatment → skinning → cold-stretching to the obtained casting material in the same way as the above sample Nos. 1 to 3 Wire and intermediate heat treatment were applied to finally obtain a round wire having a diameter of 0.2 mm or 0.175 mm. The stranded wire obtained by twisting the seven round wires thus obtained was subjected to compression processing with a compression rate of 10%, and the obtained compression stranded wire was subjected to softening treatment (continuous treatment). The continuous treatment was performed by adjusting the heat treatment conditions (wire speed, current value, etc.) so that the elongation of the wire after the heat treatment was about 30%. The characteristics of the obtained compression stranded wire (soft material) were measured in the same manner as in the above sample Nos. 1 to 3. The results are shown in Table 1. In addition, the characteristics of the obtained 0.2 mm round wire subjected to the above-described continuous treatment were measured in the same manner as in Sample Nos. 1 to 3. The results are shown in Table 1.

  As another comparative sample, Sample No. 200 with a small Sn content was prepared in the same manner as Sample Nos. 1 to 3. However, the properties of the compression stranded wire and the 0.2 mm round wire were measured as they were without being softened. The results are shown in Table 1.

As shown in Table 1, Sample Nos. 1 to 3 containing 2 to 6 mass% (here 2 to 5 mass%) of Sn and having a low oxygen concentration have high tensile strength and high rupture load, and high strength. Nevertheless, it can be seen that the elongation and impact values are high and the toughness is excellent. Specifically, sample Nos. 1 to 3 have a tensile strength of 330 MPa or more, a cross-sectional area of 0.22 mm ² (equivalent to 0.22 sq), a breaking load of 70 N or more, and a cross-sectional area of 0.13 mm ² Even in the case of (corresponding to 0.13 sq), the breaking load is 45 N or more. In Sample No.1~3 extends is 10% or more, when the cross-sectional area of 0.22 mm ^2, the impact value is 12N · m or more, the impact value 6N · Even if the cross-sectional area of 0.13 mm ² m That's it. Furthermore, sample Nos. 1 to 3 have a relatively low Sn and P content, so there is little decrease in conductivity, 20% IACS or more, and electrical resistivity is 667 mΩ / m or less. . Therefore, it is expected that sample Nos. 1 to 3 can be suitably used as, for example, a conductor of a signal line. In addition, as shown in Table 1, when the cross-sectional area is as small as 0.13 mm ² (equivalent to 0.13 sq), it contains a relatively large amount of Sn in the range of 2 to 5% by mass, resulting in higher strength and higher toughness. It can be seen that a simple conductor is obtained.

  On the other hand, although sample No. 100 of pure copper has high electrical conductivity and elongation, it turns out that it is inferior in intensity compared with sample No. 1-3. Sample No. 200 with a small amount of Sn and not subjected to softening treatment has high conductivity and strength, but is inferior in toughness as compared with Sample Nos.

  The compression stranded wire (soft material) of the prepared sample Nos. 1 to 3 is used as a conductor, and an insulating layer (thickness 0.2 mm) is formed on the outer periphery of this conductor using an insulating material (here, halogen-free insulating material). When the electric wire was produced, it was produced without any problems. Since this electric wire has sufficient mechanical properties desired for the electric wire as described above and has electric conductivity suitable for the signal line, it is expected to be particularly suitable for the signal line.

  The above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, Sn, P, oxygen content, wire diameter, and the like can be changed as appropriate.

  The electric wire of the present invention can be preferably used for wiring of a transport device such as an automobile or an airplane, various electronic components, an industrial robot, and the like. Moreover, this invention conductor can be utilized suitably for the constituent material of the said this invention electric wire.

Claims (6)

A conductor for electric wires composed of a copper alloy wire,
The copper alloy contains, by mass ratio, Sn 2% to 6%, P 10ppm to less than 300ppm, oxygen 1ppm to 50ppm, the remainder consisting of Cu and impurities,
Content of the said impurity is a mass ratio, and is a total of 200 ppm or less, The conductor for electric wires characterized by the above-mentioned.   2. The electric wire conductor according to claim 1, wherein the conductor is composed of a compression stranded wire obtained by compressing a stranded wire obtained by twisting a plurality of the wire members.   3. The electric wire conductor according to claim 1, wherein the conductor has an elongation of 10% or more.   The conductor for electric wires according to any one of claims 1 to 3, wherein the copper alloy further contains 0.05% to 0.3% of Ni by mass ratio.   The conductor for electric wires according to any one of claims 1 to 4, wherein the tensile strength is 330 MPa or more and the electrical conductivity is 20% IACS or more.   An electric wire comprising the conductor according to any one of claims 1 to 5 and an insulating layer provided on an outer periphery of the conductor.