JPH08127830A - Production of copper alloy for wire conductor and wire conductor - Google Patents

Abstract

PURPOSE: To produce a copper alloy for wire conductor, having high strength and high electric conductivity and capable of reducing the diameter and weight of an electric wire for automobile use to a greater extent, and a wire conductor. CONSTITUTION: An ingot of a copper alloy, having a composition consisting of, by weight, 0.8-2.0% Sn, 0.03-0.1% P, 0.008-0.02% Zr, and the balance Cu with inevitable impurities, is cold-worked at >=90% reduction of area, by which a linear material is prepared. Then, the linear material is annealed at 200-400 deg.C (not including 200 deg.C and 400 deg.C) for 10-400min.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy for a wire conductor and a method for manufacturing a wire conductor, which has high strength and high electrical conductivity and is excellent in ductility and is suitable as a conductor material for an electric wire for automobiles having a small diameter.

[0002]

2. Description of the Related Art Generally, electric wires used in automobiles are divided into electric power supply electric wires and control signal electric wires. Among them, for the control signal wire, a high conductivity annealed copper wire (JIS 3102) or a tin-plated annealed copper wire plated with tin is used although the required allowable current is as small as 1 A or less. Has been done. Since these annealed copper wires or tin-plated annealed copper wires have relatively low mechanical strength (tensile strength), they must be thicker than the wire diameter that is electrically necessary to secure the strength required for electric wire conductors. Is used.

By the way, in recent years, the number of wirings in the vehicle has been rapidly increasing with the increase of various on-vehicle equipments and computerization, and the increase in vehicle weight and space occupancy due to electric wires cannot be ignored. For this reason, there is an increasing demand for thinner wires and lighter weight, and currently the cross-sectional area is 0.3 mm ²
And thin-diameter compressed annealed copper stranded wire is used. This compressed annealed copper stranded wire is obtained by twisting a plurality of annealed copper strands into a stranded wire, which is passed through a die and compressed in the radial direction. However, even with this compressed annealed copper stranded wire, the diameter and weight reduction are not sufficient, and the electric wire for automobiles is required to be further reduced in diameter and weight.

In order to further reduce the diameter and weight of automobile electric wires, use of hard copper wires, which have higher mechanical strength than annealed copper wires, has been studied as electric wire conductors. In addition, the use of a copper-clad aluminum wire that is lighter than an annealed copper wire is also being considered. Further, although the electric conductivity is slightly inferior to that of the annealed copper wire, the use of a copper tin alloy wire, a phosphor bronze wire, etc. is considered because of its high mechanical strength. In particular, the copper-tin alloy wire has a cross-sectional area of 0.
There is an example in which a small diameter of 2 mm ² is used.

[0005]

However, although the hard copper wire has the advantage of being able to secure the strength even if it has a small diameter, it is not satisfactory as an electric wire for automobiles because its elongation (ductility) is extremely small. In addition, although the copper-clad aluminum wire is lightweight, it has low strength, so measures such as thickening the wire diameter are necessary to secure the required strength, and as a result, it is possible to reduce the diameter and weight. Can not achieve the purpose.

Furthermore, the copper-tin alloy wire has a cross-sectional area of 0.2 m.
Although it has been put to practical use as an electric wire conductor of m ^2, the strength is insufficient when the cross-sectional area is smaller than that. Furthermore, the phosphor bronze wire has sufficient strength, but has a conductivity of 20% IACS.
It is extremely low as less than.

The small-diameter electric wires currently required are, for example,
The conductor cross-sectional area is 0.15 to 0.2 mm ² , and the breaking load is 9.
It is 5 kgf or more and the conductivity is 45% IACS or more. That is, the conductor cross-sectional area is required to be reduced by 30 to 50% as compared with the compressed annealed copper stranded wire having a cross-sectional area of 0.3 mm ² which has been conventionally used as a signal wire. Further, the breaking load is required to be equal to or more than the breaking load (8.0 kgf) of the compressed annealed copper stranded wire, and is preferably 9.5 kgf or more. Furthermore, although the signal line is usually used with an allowable current of 1 A or less, which does not require fuse matching, there should be no signal deterioration caused by the electric resistance of the wire conductor.
The electrical conductivity needs to be at least half the electrical conductivity of the compressed annealed copper wire, in other words, 45% IACS or more.

Considering an electric conductor having a conductor cross-sectional area of 0.15 mm ² which is formed by twisting seven strands, the characteristics required for the strands are as follows. Tensile strength is
The load is 9.5 kgf or more and the cross-sectional area is 0.15 mm ²
Therefore, it is necessary to be 64 kgf / mm ² or more. Further, the electrical conductivity must be at least half that of the compressed annealed copper stranded wire, that is, at least 45% IACS, as described above. Further, in order to secure workability and terminal crimping property when the assembled wire is used, it is necessary that the elongation is 5% or more.

The present invention has been made in view of the above problems, and it is possible to satisfy these characteristics and further reduce the diameter and weight of an electric wire for an automobile. It is an object to provide a method for manufacturing an alloy and a wire conductor.

[0010]

The copper alloy for electric wire conductors according to the present invention is Sn; 0.8 to 2.0% by weight, P; 0.0.
3 to 0.1% by weight and Zr; 0.008 to 0.02
It is characterized by containing wt% and the balance consisting of Cu and inevitable impurities.

The method of manufacturing an electric wire conductor according to the present invention is S
n: 0.8 to 2.0% by weight, P: 0.03 to 0.1
% And Zr: 0.008 to 0.02% by weight, the ingot of a copper alloy containing the balance of Cu and inevitable impurities is cold-worked at a surface reduction rate of 90% or more to form a linear material. The method is characterized by including a step of obtaining and a step of annealing this linear material.

[0012]

The reason for adding each component and the reason for limiting the composition of the copper alloy according to the present invention will be described below.

Sn (Tin) Sn has the action of improving the strength of the copper alloy. However, when the Sn content is less than 0.8% by weight, the strength improving effect is not sufficient. On the other hand, Sn content is 2.0% by weight
If it exceeds, not only the effect of improving the strength commensurate with the added amount cannot be obtained, but also the conductivity is lowered. Therefore, Sn
The content is 0.8 to 2.0% by weight.

P (phosphorus) P has the effect of improving the ductility of the copper alloy. But P
If the content is less than 0.03% by weight, the effect of improving the ductility characteristics is smaller than that of the tin alloy. On the other hand, the P content is 0.
If it exceeds 1% by weight, the electric conductivity is remarkably reduced. Therefore, the P content is 0.03 to 0.1% by weight.

Zr (Zirconium) Zr has the effect of improving the heat resistance of the copper alloy.
When the Zr content is less than 0.008% by weight, heat resistance cannot be sufficiently improved. On the other hand, if the Zr content exceeds 0.02% by weight, it may hinder the improvement of ductility, and causes inconvenience such as difficulty in casting. Therefore, the Zr content is 0.008 to 0.02% by weight.

In the method of this embodiment, the ingot of the copper alloy having the above composition is cold worked at a surface reduction rate of 99% or more. If the area reduction rate during cold working is less than 99%, the increase in strength due to work hardening is insufficient and the expected tensile strength cannot be obtained.

Thereafter, this linear material is applied to, for example, 200-40.
1 at 0 ℃ (excluding 200 ℃ and 400 ℃)
Annealed for 0 to 400 minutes, its tensile strength and ductility (elongation)
To the desired range. If the temperature during annealing is 200 ° C or lower, the ductility is not sufficient, and if it is 400 ° C or higher, the tensile strength decreases. Further, if the annealing time is less than 10 minutes, the ductility recovery effect is small, and if it is 400 minutes or more, not only there is nothing contributing to the improvement of properties, but also the strength is lowered. Therefore, the annealing condition is that the temperature is 200 to 400 ° C.
(However, 200 ° C and 400 ° C are not included), and the annealing time is preferably 10 to 400 minutes. The more preferable range of the annealing temperature is 250 to 300 ° C., and the more preferable range of the annealing time is 30 to 300 minutes.

When a plurality of wire rods annealed in this way are twisted together to form an electric wire conductor, the area reduction rate is 23%.
By circularly compressing within the limit to reduce voids in the stranded wire, it is possible to obtain a conductor having a further reduced diameter and good circularity. In this case, if the surface reduction rate exceeds 23%, it becomes necessary to deform in the longitudinal direction, resulting in a marked decrease in workability. Therefore, the area reduction rate is preferably 23% or less.

[0019]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples outside the scope of the claims.

First, oxygen-free copper was added with the amount of S shown in Table 1 below.
After n, P and Zr were added and melted in an induction heating furnace, a rod-shaped ingot having a diameter of 8 mm was continuously cast. The melting and casting were performed in an argon gas atmosphere.

Next, this rod-shaped ingot is cold worked by swaging and die drawing to have a diameter of 0.161 mm.
Wire drawing (area reduction rate 99.96%) was performed. Then, it was annealed under the conditions shown in Table 1 together.

With respect to the wire rod thus obtained, the strength,
Elongation, conductivity and castability were evaluated. However, the strength and elongation were examined by a tensile test. Regarding conductivity,
It was evaluated by measuring the electric conductivity (% IACS).
Further, the castability was evaluated by the state of the surface of the rod-shaped ingot during casting.

Furthermore, as conventional examples 1 and 2, soft copper wire and hard copper wire were prepared, respectively. Then, these conventional examples 1,
For 2 as well, annealing was performed in the same manner as in Examples and Comparative Examples,
The strength, elongation and conductivity were measured. The results are summarized in Table 2.

[0024]

[Table 1]

[0025]

[Table 2]

As is clear from Table 2, Examples 1 to 1
All of 7 had good castability, and also had good strength, elongation and conductivity. On the other hand, in Comparative Example 1 having a small Sn content, the elongation and the conductivity were good, but the strength was low. In addition, Comparative Example 2 with a large Sn content
The sample had high strength, but both elongation and conductivity were low.

The ductility of Comparative Example 3 having a low P content is 4.
It was as low as 3%, which was not satisfactory. Further, in Comparative Example 4 in which the P content was large, the strength and the elongation were sufficient, but the conductivity was low.

In Comparative Example 5 in which the Zr content was low, the annealing was excessive and the strength decreased. Furthermore, in Comparative Example 6 in which the Zr content was high, the castability was poor and microcracks were generated.

The conventional example 1 which is an annealed copper wire has a strength of 2
It was as low as 1.1 kgf / mm ^2, and the elongation of Conventional Example 2 which is a hard copper wire was as low as 1%.

Next, a copper alloy having the same composition as in Example 7 was processed into a linear shape under the same conditions as in Example 7, and then annealed under the conditions shown in Table 3 below. Then, the tensile strength and elongation of these wire rods were examined. The results are summarized in Table 3 below. However, the upper numerical value in Table 3 is the tensile strength (kgf / m
m ² ) and the numerical value on the lower side is elongation (%).

[0031]

[Table 3]

As is clear from Table 3, when the annealing temperature is as low as 200 ° C. and as high as 400 ° C., the tensile strength is 64 kgf / mm ² and the elongation is 5% or more even if the annealing time is adjusted. If the conditions required for the wires of the small-diameter electric wire cannot be satisfied, and the annealing time is less than 10 minutes or more than 400 minutes, the above conditions are satisfied even if the annealing temperature is adjusted. I couldn't.

The scope of application of the copper alloy according to the present invention is not limited to the conductor of an electric wire for an automobile, and can be applied as a conductor of an electric wire used in various devices.

Next, examples and comparative examples in which the area reduction rate is variously changed will be described. Table 4 below shows the relationship between the area reduction rate when cold-working a copper alloy ingot to obtain a linear material and the tensile strength of the obtained linear material. The annealing conditions are both 270
It was heated to ℃ for 1 hour.

[0035]

[Table 4]

As shown in Table 4, when the area reduction rate is 99% or more as defined in claim 2 of the present application, a sufficiently high tensile strength is obtained.

Next, as described in claim 4, an example and a case of manufacturing a stranded wire by twisting a plurality of annealed linear materials and compressing them at a predetermined area reduction ratio Here is an example: Table 5 below shows the relationship among the twisted wire configuration, the area reduction rate, and the roundness.

[0038]

[Table 5]

However, in Table 5, the diameter of the wire and the number of the wire are shown in the configuration column. That is, in the case of 0.26 / 7, the diameter of the strand is 0.26 mm, and seven strands are twisted together. The cross-sectional area is the cross-sectional area obtained from the outer diameter.

As shown in Table 5, when the area reduction ratio is 23% or less, the twisted wire having high roundness can be obtained without the collapse of the wire.

[0041]

As described above, the copper alloy for electric wire conductors according to the present invention has a high strength and conductivity because it contains a predetermined amount of Sn, P and Zr and the balance is Cu and unavoidable impurities. It is extremely suitable as a conductor material for electric wires for automobiles having a small diameter.

Further, according to the method of the present invention, since the copper alloy is cold-worked at a predetermined surface reduction rate and then annealed under predetermined conditions, an electric wire conductor having high strength and electrical conductivity and large elongation is obtained. be able to. Further, by compressing the twisted wire under a predetermined condition, a twisted wire having a high roundness can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuki Suzuki 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Stock Company

Claims (4)

[Claims] 1. Sn: 0.8 to 2.0% by weight, P;
A copper alloy for electric wire conductors, containing 0.03 to 0.1% by weight and Zr; 0.008 to 0.02% by weight, and the balance being Cu and inevitable impurities. 2. Sn: 0.8 to 2.0% by weight, P;
A copper alloy ingot containing 0.03 to 0.1% by weight and Zr; 0.008 to 0.02% by weight, the balance being Cu and unavoidable impurities, is cold-rolled at a surface reduction rate of 99% or more. A method of manufacturing an electric wire conductor, comprising: a step of processing to obtain a linear material; and a step of annealing the linear material. 3. The temperature during annealing exceeds 200 ° C., and 4
The method for producing an electric wire conductor according to claim 2, wherein the temperature is lower than 00 ° C., and the annealing time is 10 to 400 minutes. 4. The method for producing an electric wire conductor according to claim 2, wherein a plurality of the annealed linear materials are twisted together and compressed at a surface reduction rate of 23% or less.