JP7568466B2 - Electrical wire - Google Patents

Description

The present invention relates to an electric wire comprising a center wire, a number of conductor core wires arranged to surround the center wire, and an insulator provided to cover the number of conductor core wires.

Conventionally, electric wires have been proposed as overhead distribution lines that are laid across utility poles, steel towers, etc. and used for power transmission, etc., and that have a center wire as a tensile strength member, multiple conductor core wires twisted together while surrounding the center wire, and a resin insulator as an exterior material. For example, in one conventional overhead distribution line, multiple conductor core wires are arranged to surround the outer periphery of a center wire made of a composite material in which reinforcing fibers are impregnated with molten metal (see, for example, Patent Document 1).

JP 2001-167644 A

The conventional electric wires described above can be made lighter than those using general steel wires (e.g., galvanized steel wires or aluminum-coated steel wires) as the center wire, and have an excellent balance between strength and weight. However, when using conventional electric wires in practice, when discarding used electric wires for purposes such as the maintenance of power distribution equipment, it is difficult to separate the metal portion and the reinforcing fibers from the composite material that constitutes the center wire, which makes the disposal process complicated. In other words, the environmental impact of discarding or recycling electric wires is large.

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide an electric wire that is strong and lightweight and that reduces the environmental impact when it is disposed of, etc.

In order to achieve the above-mentioned object, the electric wire according to the present invention is characterized by the following [1] to [ 4 ].
[1]
An electric wire including a center wire, a plurality of conductor core wires arranged to surround the center wire, and an insulator provided to cover the plurality of conductor core wires,
The entire center line is
It is composed of a mixed material including polybutylene succinate (PBS) and cellulose nanofiber (CNF),
It is an electric wire.
[2]
In the electric wire according to the above [1],
The mixed material constituting the center line is
Polybutylene succinate (PBS) 100 parts by weight,
Cellulose nanofiber (CNF) is 50 parts by weight or more and 100 parts by weight or less,
In a weight ratio of
It is an electric wire.
[3]
In the electric wire according to the above [1] or [2],
The insulator is
a protrusion portion protruding radially outward from an outer circumferential surface of the insulator and extending in an axial direction;
It is an electric wire.
[4]
In the electric wire according to the above [1],
The tensile strength of the center line is 380 N/mm2 or ^more and 760 N/mm2 ^{or less} .
It is an electric wire.

According to the electric wire of the above-mentioned configuration [1], a center wire made of a mixed material containing polybutylene succinate (PBS) and cellulose nanofiber (CNF) is used as a tension member. According to the experiments and considerations by the inventors, it has been revealed that by making the center wire of a mixed material containing polybutylene succinate (PBS) and cellulose nanofiber (CNF), it is possible to obtain an electric wire that has the strength required for an electric wire (e.g., an overhead distribution line) while being lighter in weight than when a general steel wire is used as the center wire. Furthermore, polybutylene succinate (PBS) is a biodegradable resin, and cellulose nanofiber (CNF) is a fibrous material extracted from cellulose, which is the main component of plants, etc. Therefore, compared to the center wire used in the above-mentioned conventional electric wire, the environmental load when disposing of the center wire can be reduced. In addition, since the center wire is covered with an insulator and isolated from the external environment when the electric wire is in use, the biodegradability of the center wire is not an issue. Therefore, this type of electric wire is strong and lightweight, and can reduce the environmental impact when it is disposed of.

According to the electric wire having the configuration of [2] above, the mixed material constituting the center wire contains 100 parts by weight of polybutylene succinate (PBS) and 50 to 100 parts by weight of cellulose nanofiber (CNF). According to experiments and considerations by the inventors, a mixed material having such a composition has excellent tensile strength, which allows the center wire to be made thinner, and also reduces the load on the processing equipment when the mixed material is processed (e.g., extrusion molding, etc.) to manufacture the center wire.

According to the electric wire of the configuration [3] above, the insulator is provided with a protrusion (so-called fin) that protrudes radially outward from the outer peripheral surface of the insulator and extends in the axial direction. As a result, when the electric wire is used as an overhead distribution line, for example, snow accumulated on the electric wire is prevented from moving around the electric wire in the circumferential direction, thereby suppressing snow from adhering to the periphery of the electric wire (snow accretion). Furthermore, since the center wire (tensile member) of the electric wire of this configuration is lighter than a general steel wire, when a lightweight wire made of aluminum or an aluminum alloy is used as the conductor core wire, the weight of the entire electric wire is particularly light. By suppressing snow accretion on such a lightweight electric wire, for example, the oscillation of the electric wire caused by snow accretion (so-called galloping, sleet jump, etc.) can be appropriately suppressed. In this respect, the contribution of the snow accretion prevention effect of the protrusion of this configuration to the electric wire is extremely remarkable.

The present invention provides an electric wire that is strong and lightweight and reduces the environmental impact when it is disposed of.

The present invention has been briefly described above. The details of the present invention will become clearer by reading the following description of the embodiment of the invention (hereinafter referred to as "embodiment") with reference to the attached drawings.

FIG. 1 is a perspective view showing an end portion of an electric wire according to an embodiment of the present invention with some of the components appropriately removed in order to facilitate understanding of the internal structure. FIG. 2 is a cross-sectional view of the electric wire shown in FIG. FIG. 3 is a schematic diagram of a manufacturing apparatus for manufacturing the electric wire shown in FIG.

The electric wire 1 according to an embodiment of the present invention will be described below with reference to the drawings. The electric wire 1 is typically used as an overhead distribution line that is laid across utility poles, steel towers, etc. and used for power transmission, etc. Therefore, the electric wire 1 is required to have strength (specifically, tensile strength) and light weight.

<Configuration of Electric Wire 1>
As shown in Figs. 1 and 2, the electric wire 1 according to this embodiment includes a round bar-shaped center wire 10 serving as a tensile member, a plurality of conductor core wires 20 twisted together around the center wire 10, and a cylindrical insulator 30 provided to cover the plurality of conductor core wires 20.

The center line 10 is made of a mixed material containing polybutylene succinate (PBS) and cellulose nanofiber (CNF). The specific composition of the polybutylene succinate (PBS) and cellulose nanofiber (CNF) that make up the center line 10 will be described later.

The specific gravity of cellulose nanofiber (CNF) is about 1.5, which is much smaller than the specific gravity of steel (about 7.8). Therefore, cellulose nanofiber (CNF) is extremely light compared to steel. According to the inventor's experiments and considerations, by constructing the center wire 10 from a mixed material containing polybutylene succinate (PBS) and cellulose nanofiber (CNF), it is possible to reduce the weight compared to using a general steel wire as the center wire while ensuring sufficient strength for the electric wire 1.

Polybutylene succinate (PBS) is a biodegradable resin that is biodegradable. Cellulose nanofiber (CNF) is a fibrous material extracted from cellulose, the main component of plants, etc. Therefore, compared to the center wires (made of a composite material of metal and fiber) used in the above-mentioned conventional electric wires, the environmental impact of the center wire 10 when disposed of is small. Furthermore, when the electric wire 1 is in use, the center wire 10 is covered with the insulator 30 and isolated from the external environment, so the biodegradability of the center wire 10 is not an issue.

The conductor core wires 20 are made of, for example, aluminum or an aluminum alloy. The twisting form of the twisted conductor core wires 20 is not particularly limited, but may be any of S twist, Z twist, and SZ twist (alternate twist). The number of conductor core wires 20 included in the electric wire 1 is not particularly limited, but is eight in this example.

The nominal cross-sectional area of the multiple conductor core wires 20 twisted around the center wire 10 is typically 25 ^mm2 or 58 ^mm2 . When the nominal cross-sectional area of the conductor core wire 20 is 25 ^mm2 , the outer diameter of the center wire 10 is preferably 4.3 mm and the outer diameter of the conductor core wire 20 is preferably 2.3 mm. When the nominal cross-sectional area of the conductor core wire 20 is 58 ^mm2 , the outer diameter of the center wire 10 is preferably 6.5 mm and the outer diameter of the conductor core wire 20 is preferably 3.5 mm. The outer diameters of the center wire 10 and the conductor core wire 20 are values before compression by a strand compression unit 44 described later (in other words, values at the time of unwinding by a conductor core wire supply unit 41 and a center wire supply unit 42 described later). Furthermore, as described in detail below, regarding the strength of the center wire 10, when the nominal cross-sectional area of the conductor core wire 20 is 25 ^mm2 , the maximum yield strength of the center wire 10 is preferably 5.5 kN or more, and when the nominal cross-sectional area of the conductor core wire 20 is 58 ^mm2 , the maximum yield strength of the center wire 10 is preferably 12.3 kN or more. In other words, the tensile strength of the center wire 10 is preferably 380 N/mm2 or ^more and 760 N/mm2 or ^less .

The cylindrical insulator 30 covers the outer circumference of the twisted conductor core wires 20. The insulator 30 is made of an insulating resin material such as polyvinyl chloride or polyethylene. As shown in Figs. 1 and 2, the outer circumferential surface of the insulator 30 is provided with a protrusion 31 (so-called fin) that protrudes radially outward and extends in the axial direction. In the example shown in Figs. 1 and 2, a pair of protrusions 31 are provided at the upper and lower end positions in the circumferential direction on the outer circumferential surface of the insulator 30. As a result, for example, when the electric wire 1 is used as an overhead distribution line, the protrusions 31 prevent snow accumulated on the electric wire 1 from moving around the electric wire 1 in the circumferential direction, and snow adhesion around the electric wire 1 (snow accretion) can be suppressed.

The insulator 30 is formed by extruding a heated and melted resin material onto the outer circumference of the multiple conductor core wires 20 that are twisted around the center wire 10, so that the resin material has a cylindrical shape with a pair of protrusions 31. This allows the center wire 10 and the multiple conductor core wires 20 that are twisted around the center wire 10 to be protected by the insulator 30.

<Apparatus and method for manufacturing electric wire 1>
Next, a manufacturing apparatus 40 for manufacturing the electric wire 1 and a manufacturing method of the electric wire 1 using the manufacturing apparatus 40 will be described.

As shown in FIG. 3, the manufacturing device 40 for manufacturing the electric wire 1 includes a conductor core wire supply unit 41 and a center wire supply unit 42. The conductor core wire supply unit 41 includes a general reel, etc., and a plurality of conductor core wires 20 are paid out from the conductor core wire supply unit 41. The center wire supply unit 42 also includes a general reel, etc., and pays out a center wire 10 that is made by kneading and extruding polybutylene succinate (PBS) and cellulose nanofiber (CNF).

Downstream of the conductor core wire supply unit 41 and the center wire supply unit 42, a twisting unit 43 is provided. A plurality of conductor core wires 20 fed from the conductor core wire supply unit 41 and a center wire 10 fed from the center wire supply unit 42 are fed into the twisting unit 43. The twisting unit 43 has a typical twisting mechanism and twists the plurality of conductor core wires 20 together to surround the center wire 10.

Downstream of the twisting section 43, a twisted wire compression section 44 and an insulator forming section 45 are provided in this order. The twisted wire compression section 44 has a general die, and compresses the multiple conductor core wires 20 twisted to surround the center wire 10 radially inward using the die. As a result, the multiple conductor core wires 20 are plastically deformed into a cylindrical shape and are tightly attached to the outer periphery of the center wire 10 as shown in Figures 1 and 2. The insulator forming section 45 has a general insulator forming mechanism, and forms a cylindrical insulator 30 provided with a pair of protrusions 31 by extruding a heated and melted resin material so as to cover the periphery of the compressed multiple conductor core wires 20. In this manner, the electric wire 1 shown in Figures 1 and 2 is manufactured.

<Preferable range of composition (weight ratio) of mixed material constituting center wire 10>
The following describes a preferred range for the composition of polybutylene succinate (PBS) and cellulose nanofiber (CNF) that constitute the center wire 10. According to experiments and considerations by the inventors, it has been found that, with regard to the composition of polybutylene succinate (PBS) and cellulose nanofiber (CNF) that constitute the center wire 10, it is preferable that the amount of cellulose nanofiber (CNF) is 50 to 100 parts by weight per 100 parts by weight of polybutylene succinate (PBS).

Specifically, it has been found that the strength required for the center wire 10 of the electric wire 1 used as an overhead distribution line can be satisfied by using 50 parts by weight or more of cellulose nanofiber (CNF) per 100 parts by weight of polybutylene succinate (PBS). Here, as the strength required for the center wire 10, for example, when the nominal cross-sectional area of the conductor core wire 20 is 25 ^mm2 , the maximum yield strength of the center wire 10 is preferably 5.5 kN or more, and when the nominal cross-sectional area of the conductor core wire 20 is 58 ^mm2 , the maximum yield strength of the center wire 10 is preferably 12.3 kN or more.

As the number of parts by weight of cellulose nanofiber (CNF) per 100 parts by weight of polybutylene succinate (PBS) increases from 50, the tensile strength of the center wire 10 increases, making it possible to reduce the diameter of the center wire 10. However, it has been found that when the number of parts by weight of cellulose nanofiber (CNF) per 100 parts by weight of polybutylene succinate (PBS) exceeds 100, the load on the extruder during extrusion of the center wire 10 can become excessively large.

As a result, by setting the composition (weight ratio) of the polybutylene succinate (PBS) and cellulose nanofiber (CNF) that constitute the center wire 10 within the above range, the center wire 10 can be made thinner due to its excellent strength, and the load on the extruder when extruding the center wire 10 can be reduced.

<Action and Effects>
As described above, according to the electric wire 1 of the present embodiment, the central wire 10 made of a mixed material containing polybutylene succinate (PBS) and cellulose nanofiber (CNF) is used as a tension member. According to experiments and considerations by the inventors, the central wire 10 made of a mixed material containing polybutylene succinate (PBS) and cellulose nanofiber (CNF) can be made lighter than a general steel wire while ensuring sufficient strength as the electric wire 1. Furthermore, polybutylene succinate (PBS) is a biodegradable resin, and cellulose nanofiber (CNF) is a fibrous material extracted from cellulose, which is the main component of plants, etc. Therefore, compared with the central wire used in the above-mentioned conventional electric wire, the environmental load at the time of disposal is small. Furthermore, since the central wire 10 is covered with the insulator 30 and isolated from the external environment during use of the electric wire 1, the biodegradability of the central wire 10 is not an issue. Therefore, the electric wire 1 according to the present embodiment has excellent strength and light weight, and can reduce the environmental load at the time of disposal.

Furthermore, according to the electric wire 1 of this embodiment, the mixed material constituting the center wire 10 preferably contains 100 parts by weight of polybutylene succinate (PBS) and 50 parts by weight or more and 100 parts by weight or less of cellulose nanofiber (CNF). According to experiments and considerations by the inventors, a mixed material with such a composition has excellent strength, making it possible to reduce the diameter of the center wire 10, and also reduces the load on the extruder when the mixed material is extruded to form the center wire 10.

Furthermore, according to the electric wire 1 of this embodiment, the insulator 30 is provided with a protrusion 31 that protrudes radially outward from the outer circumferential surface of the insulator 30 and extends in the axial direction. This makes it possible to suppress snow accumulation on the electric wire 1, for example, when the electric wire 1 is used as an overhead distribution line. Furthermore, the center wire 10 (tensile member) of the electric wire 1 is lighter than a typical steel wire, and a lightweight conductor core wire 20 made of aluminum or an aluminum alloy is used, so that the weight of the entire electric wire 1 is particularly light. By suppressing snow accumulation on the lightweight electric wire 1 in this way, for example, the oscillation of the electric wire 1 caused by snow accumulation can be appropriately suppressed. In this respect, the contribution of the snow accumulation prevention effect of the protrusion 31 to the electric wire 1 is extremely significant.

<Other Aspects>
The present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above-described embodiments, and appropriate modifications, improvements, etc. are possible. In addition, the material, shape, size, number, arrangement location, etc. of each component in the above-described embodiments are arbitrary as long as the present invention can be achieved, and are not limited.

For example, in the above embodiment, the insulator 30 is provided with a protrusion 31 that protrudes radially outward from the outer circumferential surface of the insulator 30 and extends in the axial direction. However, such a protrusion 31 does not necessarily have to be provided on the insulator 30.

Here, the features of the electric wire 1 according to the present invention described above will be briefly summarized and listed in the following [1] to [3].
[1]
An electric wire (1) comprising a center wire (10), a plurality of conductor core wires (20) arranged so as to surround the center wire (10), and an insulator (30) provided so as to cover the plurality of conductor core wires (20),
The center line (10) is
It is composed of a mixed material including polybutylene succinate (PBS) and cellulose nanofiber (CNF),
Electric wire (1).
[2]
In the electric wire (1) described in the above [1],
The mixed material constituting the centerline (10) is
Polybutylene succinate (PBS) 100 parts by weight,
Cellulose nanofiber (CNF) is 50 parts by weight or more and 100 parts by weight or less,
In a weight ratio of
Electric wire (1).
[3]
In the electric wire (1) according to the above [1] or [2],
The insulator (30) is
The insulator (30) has a protrusion (31) protruding radially outward from an outer circumferential surface thereof and extending in an axial direction.
Electric wire (1).

Reference Signs List 1 Electric wire 10 Center wire 20 Conductor core wire 30 Insulator 31 Protrusion portion

Claims (4)

An electric wire including a center wire, a plurality of conductor core wires arranged to surround the center wire, and an insulator provided to cover the plurality of conductor core wires,
The entire center line is
It is composed of a mixed material including polybutylene succinate (PBS) and cellulose nanofiber (CNF),
Electric wire. The electric wire according to claim 1,
The mixed material constituting the center line is
Polybutylene succinate (PBS) 100 parts by weight,
Cellulose nanofiber (CNF) is 50 parts by weight or more and 100 parts by weight or less,
In a weight ratio of
Electric wire. The electric wire according to claim 1 or 2,
The insulator is
a protrusion portion protruding radially outward from an outer circumferential surface of the insulator and extending in an axial direction;
Electric wire. The electric wire according to claim 1,
The tensile strength of the center line is 380 N/mm ² More than 760N/mm ² Below is the
Electric wire.

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