JPS641884B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cable core that can be effectively used for insulating strands of power cables.

(Prior Art) (Problems to be Solved by the Invention) Recently, with the rise in power transmission voltage, the size of conductors for power cables has also increased, and conductors of 2000 mm ² or more are being used.

As a result of this trend toward larger conductors, the rate of increase in the conductor's AC effective resistance relative to its DC resistance is becoming increasingly large, and there is a strong demand to reduce this. There are ways to do this.

By the way, we have discovered that an insulated wire conductor in which each wire is coated with a cupric oxide film is effective in reducing AC resistance (Japanese Patent Application Laid-Open No. 153288/1983,
-57165), but an efficient method for forming a cupric oxide film remains to be solved.

For example, various methods such as liquid oxidation and air oxidation can be considered for oxidizing the surface of a copper wire, but no definitive method has been obtained that does not require equipment costs and forms a high-quality oxide film.

Furthermore, most of the efforts to date have focused on surface oxidation of single copper wires before stranding, and sufficient consideration has not been given to the treatment of stranded wires.

For example, in the method described in JP-A-54-153288 mentioned above, in order to oxidize a single copper wire, it is heated to 300°C or higher to form a cupric oxide film on the surface, or the copper wire is oxidized with hypochlorite. There is a description of a method of forming an oxide film on the surface by immersing the wire in an oxidizing agent mixture of sodium chloride and caustic soda, but there is no description of a method of oxidizing the copper strands to the inside at once.

The same applies to JP-A-61-93508 and JP-A-61-93509.

Special Publication No. 49-36520 contains Nb-Ti, Nb-Zr,
There is a description of applying an oxidation treatment to the outer surface of a superconductor made of a superconducting material such as Nb ₃ Sn or V ₃ Ga coated with copper to form a cupric oxide film. The purpose, structure, and effects are different from oxidizing copper stranded wire.

In addition, Japanese Patent Publication No. 50-40708 discloses that in order to prevent stress corrosion cracking in overhead insulated wires, a conductor that has been annealed and stranded, or a conductor that has been mechanically stress-relieved and stranded after wire drawing, is immersed in a chemical treatment solution. Although it has been described that a cupric oxide film is formed on the surface,
The object and structure are different from those of the present invention, and the cupric oxide coating only needs to cover the surface of the outermost layer of the wire, rather than covering each strand of the stranded wire one by one.

Therefore, both have different objectives and specific means from the present invention.

(Means for Solving the Problems) The outline of the present invention focuses on an annealing line as a production line that constitutes a cable core, and an oxidation bath is placed in series with the annealing line, and the copper strands constituting the cable core are This is a method for forming an oxide film in which a cupric oxide film is formed on each strand by oxidizing immediately after annealing.

(Function) According to the present invention, the core wires that have become wires are oxidized all at once without oxidizing each of the strands constituting the cable core wire, so work efficiency is high.
In addition, since the surface of the copper wire immediately after annealing is oxidized at a high temperature, the oxidation reaction is rapid, and therefore a product of good quality can be provided at low cost.

(Example) Example 1 As shown in FIG. 1, a copper strand 20 is sent out from a delivery drum 10, guided to an electrically heated annealing device 14, annealed there, and introduced into an oxidation bath tank 16.
In this example, it also serves as a cooling water tank.

Here, the oxidizing bath 16 can be, for example, a 1-30% aqueous solution of sodium chlorite.

The oxidized copper strands 20 in this oxidizing bath are wound onto a winding drum 18.

In the above-mentioned electrical heating device 14, the copper strands 20 are heated to 500 to 800°C in a steam atmosphere and annealed, but the copper strands are not oxidized here.

However, the copper stranded wire 20 immediately after annealing is exposed to the oxidation bath 1.
6, the stranded copper wire comes into contact with the oxidizing agent at high temperature and an oxidation reaction occurs immediately, and the oxidizing agent in an aqueous solution penetrates into the inside of the stranded wire, oxidizing the surface of the internal wire. be able to.

Here, the cupric oxide film formed on the surface of the wire is 1
The thickness is approximately 10 μm, and it adheres firmly without fear of peeling. In addition, if the bath also serves as a cooling agent, the copper stranded wire can be cooled without using additional cooling water.

The stranded copper wire, on which a cupric oxide film has been formed in the oxidation bath, is wound onto a winding drum.

Example 2 FIG. 2 shows a case where a normal annealing furnace 22 was used in place of the electrical heating device 14 of Example 1, and a cupric oxide film was formed on the surface of each strand of copper stranded wire.

Embodiment 3 Figure 3 shows a wire stranding device 24 that feeds and strands copper wire from a plurality of drums and an electrical heating device 1 for annealing.
The outline of the method of making tandem line with 4 is shown,
When led to the oxidizing bath 16, the high-temperature copper stranded wires 20 come into contact with the oxidizing liquid, which boils, becomes gaseous, and penetrates into the gaps inside the stranded wires, forming a cupric oxide film on the entire surface of each strand. be done.

Note that when the oxidizing bath 16 is not linear as shown in FIGS. 1 to 3 and the copper stranded wire 20 is bent as shown in FIG. 4, the gaps between the strands widen and the oxidizing solution This makes it easier for the oxide to penetrate into the inside of the copper strands, making it possible to form an oxide film more effectively.

Although not shown in the above embodiments, a water washing and drying device may be provided after the oxidation bath, or a cable insulator extrusion device may be provided after the oxidation treatment means to carry out oxidation and extrusion coating in tandem. This allows the power cable to be manufactured more efficiently.

Furthermore, by forming an oxide film on the surface of the copper strands, the adhesion to the plastic constituting the insulator increases, and the electrical properties of the cable can be improved.

(Effects of the Invention) According to the present invention, since the high-temperature copper stranded wire immediately after annealing is introduced into the oxidation bath, the oxidation reaction is carried out extremely effectively, and the oxidizing solution easily penetrates into the inside of the stranded wire, and A cupric oxide film can be evenly formed on the surface of each strand forming a stranded wire.

[Brief explanation of the drawing]

1 to 3 are schematic diagrams showing an embodiment of the present invention, and FIG. 4 is a schematic diagram showing another example of the annealing and oxidation stage in the present invention. 10... Delivery reel, 14... Current heating device, 16... Oxidation bath, 18... Take-up reel, 20... Copper stranded wire, 22... Annealing furnace, 24...
...Twisted wire machine.

Claims (1)

[Scope of Claims] 1. A copper stranded wire, which is characterized in that the copper stranded wire constituting the cable core is passed through an oxidation bath immediately after annealing to form a cupric oxide film on the surface of each strand. Oxide film formation method. 2. The method for forming an oxide film on a copper stranded wire according to claim 1, wherein the oxidizing bath comprises an oxidizing agent dissolved in cooling water.