JPH0664948B2 - Method for manufacturing conductor for coated electric wire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a conductor for a coated electric wire that is insulation-coated with polyethylene or the like, and particularly to a method for producing a conductor for a coated electric wire that is installed between utility poles or the like. .

[Prior Art] As a conductor for an overhead distribution line that is installed between utility poles, a hard copper wire (a wire rod obtained by cold drawing of tough pitch copper or oxygen-free copper) has been used. The assembled plurality of hard copper wires are twisted together, and an insulating coating of polyethylene, polyvinyl chloride, or the like is applied to the twisted wires. Further, there is also one in which a hard copper wire is used as a single wire and an insulating coating is applied on the single wire.

[Problems to be solved by the invention] When tough pitch copper or oxygen-free copper is subjected to cold wire drawing,
Residual stress often exists on the surface of the obtained wire. As the residual stress, there is a tensile residual stress in particular. In addition, the twisted wire repulsive force that attempts to release the twist is inevitably generated on the surface of each of the twisted hard copper wires. This stranded wire repulsive force appears as tensile residual stress on the surface of each hard copper wire. Further, each hard copper wire may have a residual stress due to a winding tendency when it is wound on a drum.

In the conventional covered electric wire, the residual stress as described above may be one of the factors to cause disconnection. That is, when rainwater enters the covered electric wire, the inside of the covering layer is easily corroded, and an oxide film is formed on the surface of the hard copper wire. When such a corrosive environment and the above-mentioned residual stress influence each other, stress corrosion cracking occurs in the hard copper wire, resulting in disconnection.

When an annealed copper wire is used as the conductor for the coated electric wire, the residual stress as described above is small, so that the possibility of the stress corrosion cracking phenomenon is reduced. However, on the other hand, a decrease in tensile strength is unavoidable, and therefore, in practice, annealed copper wire cannot be used as a conductor for coated electric wire.

In order to obtain a conductor wire having excellent corrosion resistance, it is possible to electroplate Al, Zn, Sn, Ni, etc. on the surface of the hard copper wire. However, if the coating layer is formed by the plating method, pinholes are apt to occur in the coating layer. If there is such a pinhole, when the conductor wire is placed in a corrosive atmosphere, the pinhole portion is intensively corroded, and stress corrosion cracking occurs in that portion. Further, since different metals are plated, electrolytic corrosion may occur between the copper and the plated metal.

Therefore, an object of the present invention is to provide a manufacturing method capable of obtaining a conductor for a covered electric wire which maintains tensile strength and does not cause a stress corrosion cracking phenomenon.

[Means for Solving the Problems] and [Operation and Effect] As shown in FIG. 1, the method for manufacturing a conductor for a covered electric wire according to the present invention is mainly composed of copper and is elongated in the longitudinal direction. N, A is formed on the surface of the conductor 1 having a wire processing structure.
It is characterized in that one or more elements selected from the group containing r, Ne and He are ion-implanted. In FIG. 1, the ion-implanted layer is indicated by reference numeral 2.

By ion-implanting one or more elements selected from the group containing N, Ar, Ne, and He into the conductor surface, the residual stress existing on the conductor surface is relaxed, and stress corrosion cracking resistance Improve. Further, unlike the plating method, the surface layer formed by the ion implantation method does not have pinholes and its adhesion strength is high. Therefore, the conductor has excellent corrosion resistance, and the corrosion resistance is not locally deteriorated. Furthermore, since no foreign metal is present, there is no risk of electrolytic corrosion. Moreover, since the copper conductor is not contaminated, it is advantageous for recycling.

The conductor to be ion-implanted has copper as a main component and has a wire drawing structure elongated in the longitudinal direction. Therefore, the conductor has a relatively high tensile strength and can maintain the tensile strength sufficient to withstand use as a conductor for a covered electric wire. 1 selected from the group containing N, Ar, Ne and He
The ion-implanted layer composed of one kind or two or more kinds of elements does not impair the connection characteristics of the conductor mainly composed of copper.

Conductor 1 having ion-implanted layer 2 formed as shown in FIG.
Are twisted together, and an insulating coating is applied on the twisted wire. Alternatively, the conductor 1 shown in FIG. 1 may be used as a single wire, and an insulating coating may be applied on the single wire.

The conductor to be ion-implanted is not limited to a single wire. For example, as shown in FIG. 2, a plurality of conductor wires 3 are twisted together, and N, Ar, N
One or more elements selected from the group including e and He may be ion-implanted. In FIG. 2, the ion-implanted layer is designated by the reference numeral 4.

Furthermore, the conductor to be ion-implanted does not have to be a round wire, but may be, for example, a tape-shaped material.

As described above, according to the present invention, it is possible to obtain a conductor for a covered electric wire that maintains tensile strength and does not cause a stress corrosion cracking phenomenon.

[Examples] (1) Example 1 A conductor having the structure shown in FIG. 1 was manufactured. That is, diameter 2
N was ion-implanted at an acceleration voltage of 50 KeV on the surface of a tough pitch copper wire having a tensile strength of 48 kg / mm ² in mm. On this occasion,
N atom concentration is 1 in the area of 0.2 μm surface thickness
It was set to 0% or more.

The tensile strength of the tough pitch copper wire thus obtained was almost the same as that before N ion implantation. Moreover, almost no decrease in conductivity was observed after ion implantation.

Tensile stress 2 is applied to the conductor obtained as described above.
A stress corrosion cracking test with 0 kg / mm ² of ammonia solution showed that the breaking time of conventional tough pitch copper wire was 2
It did not break even after double the time.

(2) Example 2 He and Ne were deposited in a region of a thickness of 0.1 μm on one surface of a beryllium copper alloy tape 5 having a thickness of 0.25 mm and a width of 25 mm, the cross-sectional structure of which was schematically shown in FIG. The acceleration voltage 150
Ion implantation was performed with KeV. In FIG. 3, the ion implantation layer is designated by reference numeral 6.

The tape thus obtained is bent into a U shape with a curvature of 12.5R so that the ion-implanted side is on the outside,
It was left to stand under an atmosphere of ammonia vapor. For comparison, a beryllium copper alloy tape that had not been ion-implanted was similarly bent into a U shape and restrained, and then left in an atmosphere of ammonia vapor. As a result, the ion-implanted tape was not yet broken even after the time three times as long as the time when the comparative sample was broken due to stress corrosion cracking.

When the beryllium copper alloy tape obtained by the method of the present invention was used as a conductor connector, the connection characteristics were good.

(3) Example 3 As shown in the cross-sectional structure in FIG. 4, 19 conductor wires 7 made of tough pitch copper are twisted together, and Ar is ion-implanted on the surface of the stranded wire conductor at an acceleration voltage of 200 KeV. did. The ion-implanted portion is within a region having a thickness of approximately 0.2 μm at the surface exposed to the outside.

The stranded wire conductor thus obtained was subjected to the following stress corrosion cracking test while the twisted shape was restrained at both ends.

Applied stress: 20 kg / mm ² Solution used: NH ₄ Cl 53.5 g / CuCl ₂ · 2H ₂ O 4.26 g / ammonia water 21 cc / Test method: The lower end of the stranded wire conductor is immersed in the above solution,
A stress corrosion cracking test was performed at a cycle of 70 ° C., 36 hours, room temperature, and 18 hours.

For comparison, a stress corrosion cracking test under the same conditions was performed on a stranded conductor of the same shape made of tough pitch copper that was not ion-implanted. This comparative sample generated stress corrosion cracking from the outermost wire after 48 days. However, the twisted-wire conductor of the present invention having the ion-implanted layer on the surface did not cause stress corrosion cracking even after 96 days.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an example of a conductor obtained by the method of the present invention. FIG. 2 is a sectional view schematically showing another example of the conductor obtained by the method of the present invention. FIG. 3 is a sectional view schematically showing still another example of the conductor obtained by the method of the present invention. FIG. 4 is a sectional view schematically showing still another example of the conductor obtained by the method of the present invention. In the figure, 1 is a conductor and 2 is an ion implantation layer.

Claims (3)

[Claims] 1. A surface of a conductor mainly composed of copper and having a wire drawing structure elongated in the longitudinal direction is provided with N, Ar, N.
A method for producing a conductor for a covered electric wire, comprising ion-implanting one or more elements selected from the group containing e and He. 2. The method for producing a conductor for covered electric wire according to claim 1, wherein the conductor is a single wire conductor. 3. The method for producing a conductor for a covered electric wire according to claim 1, wherein the conductor is a stranded conductor.