JPS63138607A - Covered wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention collects a plurality of conductor strands into a stranded wire, and this 1! The present invention relates to a covered electric wire in which an insulating coating such as polyethylene is applied on the wire, and in particular to a covered iWi wire that is installed between telephone poles or the like.

[Prior Art] Hard copper wire has conventionally been used as a conductor for overhead distribution lines that are installed between utility poles. A plurality of assembled hard copper wires are twisted together, and an insulating coating made of polyethylene, polyvinyl chloride, or the like is applied to the twisted wires.

[Problems to be Solved by the Invention] On the surface of each stranded hard copper wire, a stranded wire repulsive force that tends to untwist is inevitably generated.

This twisted wire repulsive force appears as tensile residual stress on the surface of each hard copper wire. In addition, each hard copper wire may have residual stress due to curling curls formed when it was wound around a drum.

Conventional coating i! In the case of wires, the residual stress as described above may be one of the causes of wire breakage.

That is, when rainwater enters the covered wire, the inside of the covering layer becomes a corrosive environment, 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 interact with each other, stress corrosion cracking occurs in the hard copper wire, resulting in wire breakage.

If annealed copper wire is used as the conductor for the covered electric wire, the residual stress as described above is small, so the possibility of stress corrosion cracking occurring is reduced. However, on the other hand, the tensile strength inevitably decreases, and therefore, in practice, annealed copper wire cannot be used as a conductor for coated wires.

Adding Ni to Cu improves corrosion resistance.

Therefore, structural materials that require corrosion resistance often have
A Cu alloy containing Ni is used.

However, when Ni is added to Cu, the electrical conductivity decreases. Therefore, it is not preferable to entirely use a Cu alloy containing Ni as a conductor for a covered electric wire.

Therefore, an object of the present invention is to provide a coated wire that maintains a predetermined tensile strength and electrical conductivity and does not suffer from stress corrosion cracking phenomena.

[Means for Solving the Problems] The present invention provides a covered electric wire in which a plurality of conductor strands are assembled into a stranded wire, and an insulating coating is applied to the stranded wire. and,
The conductor wire located at least in the outermost layer of the stranded wire is characterized in that its core portion is made of Qu, and its surface layer portion is made of a CIJ alloy containing 5 to 70% by weight of Ni.

[Operations and Effects of the Invention] It is well known that the fractured surface of a conductor broken due to stress corrosion cracking is always covered with a black coating.

This black film is a copper oxide film. This is considered to be based on the following phenomenon. Due to the influence of rainwater that has entered between the insulation coating layer and the stranded conductor, the surface of the conductor strands becomes dry or wet. Through this repeated drying and wetting, an oxide film is formed on the surface of the conductor wire. When stress is applied to the conductor wire, the oxide film formed on the surface of the conductor wire is destroyed, and another oxide film is formed on the newly appeared surface. When this phenomenon is repeated many times, the formation of an oxide film progresses toward the center.
Eventually, the conductor wire will break.

Therefore, in order to prevent stress corrosion cracking, an oxide film should not be formed on the surface of the conductor wire even if it comes into contact with rainwater. This invention uncovers this knowledge.

FIG. 1 is a sectional view showing an example of a stranded wire for a covered electric wire according to the present invention. The illustrated stranded wire is made by twisting a plurality of conductor wires 1 together.

An insulating coating such as polyethylene is applied to this stranded wire,
It becomes a covered wire. Each conductor strand constituting the stranded wire has a core 2 made of Cu and a surface layer 3 made of Cu.

It is a Cu alloy containing Ni.

Since the surface layer portion of each conductor element wire 1 is made of a Cu alloy containing Ni, it is possible to prevent an oxide film from being formed on the surface of the conductor element J111. Therefore, even if stress is applied to the conductor strand 1, the progress of the stress corrosion cracking phenomenon described above can be effectively prevented. Furthermore, since the core portion 2 of each conductor cable wire 1 is made of Cu, it is possible to prevent a decrease in the electrical conductivity of the conductor as a whole.

In the stranded wire shown in FIG. 1, the surface layer of each conductor element s1 is made of Ni.
It is a Cu alloy containing. However, it is not necessary that the surface layer portions of all the conductor wires constituting the stranded wires be made of such a Cu alloy. For example, C
The C0
A Ni/Cu composite may also be used.

Table i of conductor strands! The amount of Ni contained in the Cu alloy (2) is limited within the range of 5 to 70% by weight in order to exhibit a good corrosion resistance improvement effect.

Further, the volume fraction of the surface layer containing 5 to 70% by weight of N1 is preferably less than 5%. This is based on the following reasons. A Cu alloy containing Ni has a higher specific resistance than tough pitch copper or oxygen-free copper. Therefore, if the volume fraction of the Cu alloy containing Ni is 5% or more, the specific resistance as a conductor rest becomes too large as a conductor for an electric wire.

Methods for producing conductor wires whose surface layer is made of a Cu alloy containing N1 include the cladding method, which involves inserting C1 into a CuNi tube and reducing its surface area, and hot extrusion or isostatic pressure extrusion of the CuNi tube and CLI rod. There is an extrusion method in which wire is drawn after extrusion processing. Alternatively, caNts can be applied to the surface of the Cu wire by CVD such as thermal CVD, plasma CVD, or low pressure CVD.
It is also possible to adopt a method of forming the layer by a method such as a sputtering method, a plating method, or the like. Further, after forming CuNi1ll on the surface of the wire by CVD, sputtering, or plating, surface reduction processing such as stretching may be performed.

In order to satisfy the above-mentioned volume ratio, CVD, sputtering, or plating is more suitable than cladding or hot extrusion.

Furthermore, Cu constituting the core and CuN constituting the surface layer.
In order to improve the adhesion with the i-alloy, one or more layers of a single metal or an alloy of two or more elements may be disposed at the interface. Furthermore, a polymer coating layer may be formed around the strands to improve stress corrosion cracking resistance or insulation.

[Example 1] Diameter 6.0! Illφ tough pitch copper wire was prepared.

It also contains 10% by weight of Ni and has an outer diameter of 6.8111φ.
A CuNi alloy tube with an inner diameter of 6.4 φ was prepared. Then, a tough pitch copper wire was inserted into the CuNi alloy tube and cladded to a diameter of 6.151111+1φ using a high-angle die. This Cu Ni /Ctl complex is
．． The wire was drawn to a diameter of 0111+1φ to obtain a conductor strand.

After collecting 19 of the above conductor strands into a twisted wire, a polyethylene coating was applied. Then, when a stress corrosion cracking test was conducted by injecting diluted ammonia water between the conductor and the conductor, no breakage of the conductor was observed even after 3 months had passed.

For comparison, a coating using hard copper wire as the conductor element 'I!
When a similar test was conducted on 11m, the conductor developed stress corrosion cracking after 1 month, and l! 1si1shita.

[Example 2] A CuNi alloy tube containing 301ff1% of Ni, having an outer diameter of 260 mmφ, an inner diameter of 240 mmφ, and a length of 5001 Ill was prepared. Also, the outer diameter is 238fflI! An oxygen-free copper rod with lφ and length of 480 m5 was prepared. And Cu
An oxygen-free copper rod was inserted into a Ni alloy tube, both sides of the tube were covered with oxygen-free copper, and then vacuum sealed by electron beam welding. This was placed in a furnace maintained at a temperature of 700°C, and at 3 hours
! i was extruded by hot extrusion to give 3Q+ms+φ. Then, cut off the Cu parts at both ends, and
Only the i/CI composite was wire-drawn to a wire of 2', 0IllWφ, which was used as a conductor wire.

After collecting 19 of the above conductor strands into a twisted wire, a polyethylene coating was applied. Then, when a stress corrosion cracking test was performed by injecting diluted ammonia water between the coating layer and the conductor, no breakage of the conductor was observed even after 3 months had passed.

[Example 3] A tough pitch copper wire with a diameter of 2.0IIIlφ was made of Cu on four sides.
-30% N: By continuously supplying the CuNi film to the surface of the tough pitch copper wire into a sputtering device surrounded by a target, a conductor element wire was formed. The CuNi film thickness was approximately 10 μm.

After collecting 19 of the above conductor strands into a twisted wire, a polyethylene coating was applied. Then, when a stress corrosion cracking test was conducted by injecting diluted ammonia water between the coating layer and the conductor, no breakage of the conductor was observed even after 3 months had passed.

[Example 4] Diameter 2. An oxygen-free copper wire of ○Illφ was continuously supplied into the plasma reaction vessel. Into the plasma reaction vessel, cu
caa gas at a rate of 0.3fl/ll1in, Ni
(Go), gas is fed at a rate of 0.2 fL/l1in, and Ar gas is fed at a rate of 1u/win. Plasma was generated between the parallel plate electrodes using 13.56 MHz radio waves, and carbon was applied to the oxygen-free copper wire.
A uNi alloy layer was formed to obtain a conductor wire. The thickness of the CuNi alloy layer was 5 μm.

The 19 conductor strands were assembled into a stranded wire, which was then covered with polyethylene. Then, when a stress corrosion cracking test was conducted by injecting diluted ammonia water between the coating layer and the conductor, no breakage of the conductor was observed even after 3 months had passed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a stranded conductor for N electric wires according to the present invention. In the figure, 1 is a conductor strand, 2 is a core portion, and 3 is a surface layer portion. Figure 1

Claims (2)

[Claims] (1) It is a covered electric wire in which a plurality of conductor strands are assembled into a stranded wire and an insulating coating is applied to the stranded wires, and at least the conductor strand located in the outermost layer of the stranded wire has a core. With Cu,
A coated electric wire, the surface layer of which is made of a Cu alloy containing 5 to 70% by weight of Ni. (2) The covered electric wire according to claim 1, wherein the surface layer portion has a volume percentage of less than 5%.