JPH10283844A - Steel core aluminum strand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease nicking (pressure crush) of the innermost layer aluminum element wires of a steel core aluminum strand. SOLUTION: Molded steel element wires 11 are used as the outermost layer element wires of a steel strand 12, and the peripheral surface of the strand 12 is made flat. Aluminum element wires 13 (circular or molded) are twined on the periphery of this steel strand 12 so that a steel core aluminum strand 14 is accomplished. In the stretching operation at the time of installing overhead this aluminum strand 14, a pressure is applied between the innermost layer aluminum element wires 13a and the steel strand 12 having a higher hardness at the time of passing a metallic wheel but pressure concentration on the innermost layer aluminum element wires 13a is relieved because the peripheral surface of the steel strand 12 is flat and the innermost layer aluminum element wires 13a and steel strand 12 make linear contact, different from the case of contacting of circular element wires with one another which takes place in point contacting, so that the pressure concentration on the innermost aluminum element wires 13a is mitigated to lead to a reduction of nicking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel core aluminum stranded wire used for an overhead power transmission line, and more particularly, it is suitable for use as an overhead power transmission line for long-distance extension with little nicking (crushing) of an aluminum wire. It relates to steel core aluminum stranded wires.

[0002]

2. Description of the Related Art As shown in FIG. 9, a steel stranded wire 2 obtained by twisting a steel wire 1 such as a galvanized steel wire is disposed at the center as a tension member, and an aluminum wire 3 (the innermost aluminum Steel core aluminum stranded wires 4 obtained by twisting element wires 3a) are widely used as overhead power transmission lines because they can easily realize characteristics of light weight and high tension. In this type of conventional steel core aluminum stranded wire 4, as shown in the figure, a circular wire (round wire) is used as the steel wire 1 constituting the steel stranded wire 2.

[0003]

By the way, as an extension work in erection work of an electric wire to a transmission line, in general, 1 wire is required.
After deploying a wire rope to draw a wire on a wheel set at the arm of each tower in the extension section with a hand-rolled wire, connect the wire to its end and pull out the end of the wire rope with a winch. As a result, a method of replacing wire ropes with electric wires has been implemented. In this case, in addition to the back tension to be given to the electric wire by the wire drawing vehicle, there is resistance (car wheel resistance) in the wheel car installed in each steel tower.
It becomes quite large, such as 0 kgf. When the wire is pulled on the wheel with such a large tension, the wire receives a large pressing force from the wheel. When the wire to be extended is a steel core aluminum stranded wire 4, the steel core aluminum stranded wire 4 which has undergone such a pressing force in each wheel and is subjected to such a pressing force is provided with the aluminum wire 3
Permanent deformation called nicking occurs.

[0004] This nicking is caused by the contact between aluminum strands, but since there is a large difference in hardness between aluminum and steel, in particular, the aluminum strand 3 in contact with the hard steel strand 1, that is, the innermost aluminum strand The largest nicking occurs at 3a. Since the conventional steel strands 2 are all composed of the circular steel strands 1, the contact between the outermost layer of the steel strands 2 and the innermost aluminum strand 3a is in a point contact state.
When passing through the wheel, the innermost aluminum element wire 3a is squeezed on the wheel in a state of point contact. Therefore, large nicking occurs as described above. Regarding the degree of nicking, a formula for calculating the average nicking rate of the steel core aluminum stranded wire (details omitted) has been proposed as an empirical formula, which was calculated from the results of a simulation test in the test site. In actual transmission lines, the nicking rate generally increases significantly due to the topography and other track conditions.

[0005] The above-mentioned nicking is a permanent deformation that occurs in the aluminum wire, which causes a reduction in the cross-sectional area of the aluminum wire, resulting in a decrease in tensile strength of the aluminum wire, a reduction in fatigue limit stress, and the like. Will be. This nicking
It depends greatly on the wire tension, the wheel contact angle, the wheel diameter and the number of passes through the wire during the wire drawing operation. In particular, since the wire tension and the number of passes through the wheel significantly affect the length of the wire drawing section. Nicking increases in proportion. In mountainous areas, a long line is usually used for one long line section. In other cases, a long line may be necessary. As a result, the nicking increases, resulting in a decrease in the tensile strength of the electric wire and a decrease in the vibration fatigue limit, which may be a restriction on long distance extension.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and it is possible to reduce nicking of an aluminum wire at the time of wire drawing work and to make a steel core aluminum stranded wire capable of long distance wire drawing. The purpose is to provide.

[0007]

SUMMARY OF THE INVENTION The present invention, which solves the above-mentioned problems, provides a steel core aluminum stranded wire in which an aluminum element wire as a conductive path is twisted around the outer periphery of a steel stranded wire disposed as a tension member at the center, At least the outermost strand of the steel strand is formed of a formed strand, and an outer peripheral surface of the steel strand is smoothed.

[0008]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to the embodiment shown in FIGS. FIG. 1 shows a steel stranded wire 12 according to an embodiment of the steel core aluminum stranded wire of the present invention. The steel stranded wire 12 is formed around a center circular galvanized steel wire 10 by a galvanized steel wire. 11 is twisted into one layer to make the outer peripheral surface smooth. And
For example, as shown in FIG. 2, the steel stranded wire 12 is disposed at the center as a tension member, and a circular aluminum wire 13 is twisted around the periphery thereof into, for example, two layers to form a steel core aluminum stranded wire 14.
Is configured. The innermost aluminum strand is denoted by 13a. Also,
As shown in FIG. 3, a formed aluminum strand 23 (the innermost aluminum strand is indicated by 23a) is twisted into, for example, two layers around the steel strand 12 to form a steel core aluminum strand 24. Can also. Further, as shown in FIG.
Around the periphery of the molded aluminum wire 33 (the innermost aluminum wire 33
a) may be twisted into, for example, two layers, and a circular aluminum wire 33 ′ may be twisted into the outermost layer to form a steel core aluminum stranded wire 34.

In the above-mentioned steel core aluminum strands 14, 24, 34, the outermost layer of the galvanized steel strand 11 of the center steel strand 12 as a tension member is a formed strand, and the steel strand 1
2 is smoothed, so that the innermost aluminum strands 13a, 23a, 33a to be twisted around the outer circumference and the steel stranded wire 12 are in contact with the wire (in the case of FIG. 2) or the surface contact (in the case of FIG. 2). 3 and 4). Therefore, the pressure acting on the innermost aluminum strands 13a, 23a, 33a from the steel strand 12 side is reduced, and the innermost aluminum strands 13a, 23a, 33a are reduced.
Nicking of 23a and 33a is reduced. This gives
Restrictions on long-distance drawing are reduced, and long-distance drawing can be performed longer than before.

The above-described steel stranded wire 12 is a single-layer stranded wire. However, when a multi-layer stranded steel stranded wire is used, as shown in FIG. 5, a central steel wire 40 and an inner-layer steel wire 40 are used. May be a circular galvanized steel strand, and a formed strand may be used as the outermost galvanized steel strand 41 to form a steel stranded wire 42. Then, for example, as shown in FIG.
For example, similarly to FIG. 4, a formed aluminum wire 43 (which is the innermost aluminum wire) and a circular aluminum wire 43 'are twisted around the outer periphery of 2 to form a steel core aluminum wire 44.

As shown in FIG. 7 or FIG. 8, like the aluminum core stranded wire 54 or 64, the formed steel wire 51 or 61 in the steel stranded wire 52 or 62 of the tension member is used.
Alternatively, a molded aluminum-coated steel wire can be used. FIG.
Is a formed aluminum covered steel wire in which an aluminum coating 51b is formed around a formed steel wire 51a. The formed steel wire 61 in FIG. 8 is a formed aluminum covered steel wire obtained by applying an aluminum coating 61b to a circular steel wire 61a and then processing it into a fan shape by drawing. In the illustrated example, a circular aluminum wire 5 is provided around the outer periphery of the steel stranded wire 52 or 62 of the tension member.
3 or 63 (the innermost aluminum strand is 53a or 63a
Are twisted into, for example, two layers.

The steel strand of the steel strand is not limited to the galvanized steel wire and the aluminum-coated steel wire described above, but various steel wires such as a galvanized invar wire and an aluminum-coated invar wire can be used. Further, as the aluminum wire around the steel wire, an aluminum wire such as a hard aluminum wire or an aluminum alloy wire can be used.

Further, in each of the above-mentioned embodiments, a smooth steel stranded wire having an outer peripheral surface is obtained by using a formed steel wire having a fan-shaped cross section as the outermost wire of the steel stranded wire. Since a certain degree of nicking prevention effect can be obtained even if the entire outer peripheral surface is not smooth, a normal steel stranded wire consisting of twisted circular steel wires alone is passed through a circular hole and compression-molded to form the outermost layer. It is also conceivable to obtain a partially smooth surface by partially crushing a circular steel wire.

[0014]

According to the steel core aluminum stranded wire of the present invention, the outermost layer of the steel stranded wire serving as the tension member is formed of a formed wire, and the outer peripheral surface of the steel stranded wire is smoothed. The contact between the innermost aluminum strand and the steel strand that is twisted around its outer periphery becomes wire or surface contact, and the pressure acting on the innermost aluminum strand from the steel strand side is reduced. Nicking of the wire could be reduced. As a result, restrictions on long-distance wire drawing have been reduced, and it has become possible to perform long-distance wire drawing longer than before.

[Brief description of the drawings]

FIG. 1 is a sectional view of a steel stranded wire in a steel core aluminum stranded wire according to one embodiment of the present invention.

FIG. 2 is a sectional view of a steel core aluminum stranded wire according to one embodiment of the present invention using the steel stranded wire of FIG. 1;

FIG. 3 is a cross-sectional view of a steel core aluminum stranded wire according to another embodiment of the present invention using the steel stranded wire of FIG. 1;

FIG. 4 is a sectional view of a steel core aluminum stranded wire according to still another embodiment of the present invention using the steel stranded wire of FIG. 1;

FIG. 5 is a sectional view showing another embodiment of the stranded steel wire according to the present invention.

6 is a cross-sectional view of a steel core aluminum stranded wire according to one embodiment of the present invention using the steel stranded wire of FIG. 5;

FIG. 7 is a cross-sectional view of a steel core aluminum stranded wire showing still another embodiment of the present invention.

FIG. 8 is a cross-sectional view of a steel core aluminum stranded wire showing still another embodiment of the present invention.

FIG. 9 is a cross-sectional view of a conventional steel core aluminum stranded wire.

[Explanation of symbols]

11, 41, 51, 61 Formed steel strand (outermost strand of steel strand) 12, 42, 52, 62 Steel strand 13, 23, 33 (33 '), 43, 53, 63 Aluminum strand 13a , 23a, 33a, 43a, 53a, 63a
Innermost aluminum wire 14, 24, 34, 44, 54, 64 Steel core aluminum stranded wire

Claims (1)

[Claims] 1. A steel core aluminum stranded wire in which an aluminum wire as a conductive path is twisted around the outer periphery of a steel stranded wire disposed at the center as a tension member, wherein at least the outermost layer wire of the steel stranded wire is formed by a forming element. A stranded steel core aluminum wire characterized by having a smooth outer peripheral surface of the stranded steel wire.