JPH10321050A - Composite strand and lightweight, low dip overhead wire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make lightweight, give high tension characteristic, and suppress increases in dip at high temperatures and fatigue failure in actual work by covering the outside of a matrix made of a fusible metallic material, in which long fibers are buried as a reinforcing material with an aluminum base or copper base material. SOLUTION: Long fibers of preferably polyparaphenylene benzobisoxazole fibers which show negative coefficient of linear expansion, which are lightweight and have appropriate strength, and thereby, high strength, high elasticity, high heat resistance, and high flame resistance are obtained. A fusible metallic material is preferably selected from among Zn, Bi, Tl, Sn, Pb, and their alloy, having a melting point of 300 deg.C or lower and suitable for soldering. In order to prevent a drop in strength, the volumetric occupying ratio of long fibers in a complex material with the fusible metal material is set to 15-90%. The fusible metallic material covered with a copper base material having high melting point is melted or softened when the temperature of an electric wire, is raised, force of constraint with the long fibers is weakened, and thermal stresses between them are relaxed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite wire and a light-weight, low-sagging overhead electric wire using the same, and more particularly, to a light-weight, excellent sag suppressing effect at a high temperature, and a high efficiency in operation. A composite strand that is not prone to fatigue fracture,
The present invention relates to a lightweight, low-sagging overhead electric wire using the tension member as a tension member.

[0002]

2. Description of the Related Art Conventionally used overhead power transmission lines are:
The structure is such that a steel core obtained by twisting steel wires is used as a tension member, and a transmission line made of, for example, Al or an Al alloy is twisted and arranged around the tension member. Then, the whole is stretched between the steel towers with high tension to form a transmission line.

In the case of an overhead transmission line, the transmission capacity can be increased by increasing the load current. Therefore, in order to increase the transmission capacity, it is necessary to flow a large current through the transmission line. However, in the case of the above-described steel core Al stranded wire, the shared tension of the steel core, which is a tension member, increases due to a rise in temperature with an increase in load current, and the sag tension also fluctuates with a change in temperature. For this reason, there is a problem in that an overhead transmission line having a steel core as a tension member cannot expect a sag suppression effect when the transmission capacity is increased. Also, since the steel core has a large weight per unit length, the aluminum core wire of the steel core is liable to hang down by its own weight, and therefore, ancillary equipment capable of withstanding the need is required.

[0004] For these reasons, various lightweight low-loose overhead electric wires have been developed in which a tension member is made of a material having a small linear expansion coefficient instead of a steel core. For example, FR having a structure in which a long carbon fiber is used as a reinforcement and various plastics are used as a matrix and the reinforcement is embedded.
It is known that a P wire is used as a tension member.

When the above-mentioned FRP wire is actually operated as a tension member of an overhead transmission line, if the temperature of the overhead transmission line rises or falls based on the increase or decrease of the load on the overhead transmission line, the FRP wire is accordingly caused. The wire also expands and contracts.
However, in the case of the above-mentioned FRP wire, there is a large difference between the linear expansion coefficient of the carbon fiber as the reinforcing material and the linear expansion coefficient of the resin matrix that binds the carbon fibers. Generally, the value of carbon fiber is small and the value of resin matrix is large.

Therefore, when the FRP wire is expanded or contracted due to the above-described change in the wire temperature, thermal stress is generated between the reinforcing material and the matrix, and thermal fatigue is accumulated with time. In the worst case, the FRP wire ( Tension member) may cause fatigue failure. Further, the above-mentioned FRP wire is a material that is lightweight, has a small linear expansion coefficient, and has high tensile properties. However, even if such an FRP wire is used as a tension member, the wire of the obtained overhead transmission line as a whole is obtained. The expansion coefficient (hereinafter referred to as the equivalent linear expansion coefficient) indicates a value of about 18 × 10 ⁻⁶ / ° C., and the sag increases as the wire temperature increases.

Further, when the shared tension is applied to the tension member by 10
Even when the temperature rises to or above the transition point temperature at which 0% shift occurs, the FRP wire (tension member) elongates, so that the sag of the overhead transmission line increases with the temperature rise. On the other hand, as another tension member, a composite of FRM using lightweight inorganic fibers such as carbon fiber, silica fiber, SiC fiber, and boron fiber as a reinforcing material, and a low melting point metal such as zinc, tin, and bismuth as a matrix. An element wire is known (see Japanese Patent Application Laid-Open No. 1-104732).

[0008] In the case of this composite element wire, during actual operation as a tension member, fatigue failure, which can occur in the case of an FRP wire, is unlikely to occur. However, for example, when the load on the overhead power transmission line increases and the temperature of the electric wire becomes higher than the melting point of the low-melting-point metal that is the matrix, the low-melting-point metal is melted and the transmission line disposed outside the tension member is melted. A situation occurs in which the fluid flows out of the gap between the electric wires.

[0009] Therefore, in the case of this composite elementary wire, it can be operated only in a state where the wire temperature is lower than the melting point of the matrix. That is, an overhead transmission line having the composite strand as a tension member cannot practically transmit a large load current.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the conventional tension member, and has not only a light weight and a high tensile strength, but also a small increase in the sag at a high temperature, and furthermore, the actual operation of the tension member. An object of the present invention is to provide a composite element wire that is less likely to cause fatigue failure and a lightweight low-loose overhead wire using the composite element as a tension member.

[0011]

In order to achieve the above object, in the present invention, a long fiber is used as a reinforcing material, a fusible metal material in which the long fiber is embedded is used as a matrix, and the outside of the matrix is used. Is coated with an aluminum-based or copper-based material. In particular, the long fiber is made of polyparaphenylene benzobisoxazole fiber, and the fusible metal material is
A composite wire made of zinc, bismuth, thallium, tin, lead or an alloy thereof is provided.

Further, in the present invention, there is provided a light-weight, low-sagging overhead electric wire characterized in that the above-mentioned composite wire bundle is used as a tension member.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a composite strand will be described. As shown in FIG. 1 which is a cross-sectional view, this composite strand is composed of a long fiber 1 as a reinforcing material, a matrix 2 in which the reinforcing fiber is embedded, and a layer 3 covering the outside of the matrix 2.

That is, the long fiber 1 and the matrix 2 are a fiber reinforced composite (composite), and the outside thereof is covered with the material constituting the layer 3. Here, the long fiber 1 is an element for defining the strength characteristics of the entire composite strand, and is used that is lightweight and has excellent strength characteristics such as tensile strength. As the long fiber 1, any material may be used as long as it is lightweight and has appropriate strength characteristics as a tension member. For example, polyparaphenylene benzobisoxazole fiber, aramid fiber, etc. Organic fibers; and inorganic fibers such as carbon fibers, silicon carbide fibers, alumina fibers, boron fibers, and glass fibers.

Considering that the composite wire actually functions as a tension member of an overhead transmission line, it is preferable that the coefficient of linear expansion be as small as possible so that thermal expansion due to a rise in the temperature of the wire is reduced. Most preferably, the fiber has a negative value. In view of the above, as the long fiber 1 used in the present invention,
Polyparaphenylene benzobisoxazole fibers are most preferred.

The polyparaphenylene benzobisoxazole fiber (Poly (p-phenylene-2,6-benzobisoxazole) f
iber (hereinafter, referred to as PBO fiber) is represented by the following formula:

[0017]

Embedded image

This is a fiber obtained by spinning liquid crystal of polyparaphenylene benzobisoxazole having a repeating unit of This PBO fiber has a tensile strength (Ts) of about 5.5 GPa, an elastic modulus (E) of about 280 GPa, and a melting point of 600 to 650.
° C, oxygen index 50-55, density (ρ) about 1.56 g /
cm ³ , a coefficient of linear expansion (α) of about −6 × 10 ⁻⁶ / ° C., high strength, high elasticity, excellent heat resistance and flame retardancy,
Moreover, it is lightweight. Since the coefficient of linear expansion is a negative value, it has a property that it contracts with increasing temperature.

As the matrix 2 in which the PBO fibers 1 are embedded, a fusible metal material that softens or melts at a relatively low temperature is used. In particular, a material that has good wettability to the PBO fiber of the melt and is soft at room temperature is suitable. For example, solder (melting point: 200 to 300 ° C.), tin (melting point: 232 ° C.), zinc (melting point: 419 ° C.) ), Lead (melting point 3
28 ° C.), bismuth (melting point 271 ° C.), thallium (melting point 303 ° C.), and the like. These may be used alone or as an alloy in which two or more kinds are combined. In particular, solder is preferred.

Here, in the composite material comprising the long fibers 1 and the matrix 2 described above, the volume occupancy of the long fibers is 15 to 90% (therefore, the volume occupancy of the matrix is 10 to 85%). It is preferable to set as follows. If the volume occupancy of the long fibers is less than 15%, the strength characteristics of the entire composite material, particularly the tensile strength, tend to decrease, and the effect as a tension member is reduced. On the other hand, if it exceeds 90%, the amount of the fusible metal material is too small to tie the long fibers sufficiently, so that the strength characteristics of the composite material begin to decrease. Particularly preferred volume occupancy of long fibers is 40 to 6
0%.

The matrix 2 made of this fusible metal material
Is coated with a copper-based or aluminum-based material 3. All of these materials have excellent conductivity and melting points of 1084 ° C and 660 ° C, respectively.
° C, and has a higher melting point than the material constituting the matrix 2. Therefore, even if the temperature at which the fusible metal material of the matrix is melted, the situation where the coating material 3 melts does not occur.

As the above-mentioned material, in the case of copper,
Copper alone or a copper alloy is preferred, and in the case of aluminum, aluminum alone or an aluminum alloy is preferred. The thickness of the coating is not particularly limited, but if it is too thick, the composite wire becomes heavy and goes against the demand for weight reduction, and if it is too thin, its mechanical strength is reduced and external force is applied. It is preferable that the thickness be about 0.3 to 1.0 mm, since this may easily cause breakage.

This composite strand has the following functions and effects. That is, when incorporated as a tension member of an overhead transmission line, when the temperature of the electric wire rises near or above the melting point of the fusible metal material constituting the matrix, the fusible metal material softens or melts. I do. For this reason, the binding force of the matrix to the long fibers as the reinforcing material is weakened, and the long fibers have more freedom to move in the longitudinal direction of the composite strand, and the thermally expanded long fibers and the softened or melted matrix. The thermal stress is remarkably relaxed between.

When a temperature drop occurs, the long fibers thermally shrink in the softened or molten fusible metal material. The thermal stress generated between them is extremely small. That is,
Even when the composite wire is repeatedly subjected to a temperature change of a temperature rise and a temperature drop, almost no thermal stress is generated between the long fiber and the matrix, so that the fatigue fracture is well prevented.

When the fusible metal material is completely melted and liquefied, the long fibers can be thermally expanded and contracted almost without being restricted by the matrix. In this case, since the outermost coating 3 is not melted, a situation in which the melt of the fusible metal material flows out does not occur. In the composite strand in such a state, its thermal expansion and contraction is basically regulated by the linear expansion coefficient of the long fiber. Therefore, by using a long fiber having a small linear expansion coefficient, it is possible to suppress an increase in the sag of the composite element even at a high temperature.

As described above, the coating of the outermost layer is as follows.
When the fusible metal material is melted, it acts as a sheath for preventing the melt from flowing out. In addition, it acts as follows. For example, in the case where the long fiber is a fiber such as PBO fiber which is liable to be deteriorated by ultraviolet rays, the long fiber is prevented from being deteriorated by light, and thus has a function of securing reliability as a tension member for a long period of time. .

This composite strand can be manufactured as follows. That is, first, after the long fibers are bundled to a predetermined thickness, the fibers are impregnated with the melt between the fibers by immersion or continuous running in a melt of a fusible metal material such as a molten solder. Cool the whole. As a result, a wire that is a fiber-reinforced metal composite having a predetermined diameter is obtained.

Thereafter, the above-mentioned wire is introduced into a metal pipe made of copper or aluminum and having a predetermined thickness and an inner diameter, and the entire composite wire having a predetermined diameter is formed by, for example, drawing. can get. At this time, the volume occupancy of the long fibers and the fusible metal material can be set to an appropriate value by adjusting the number of bundles of the long fibers, the thickness after the bundle, and the like.

FIG. 2 is a sectional view showing an example of a lightweight low-loose overhead wire according to the present invention. In this electric wire, a plurality (seven in the figure) of the composite strands shown in FIG. 1 are bundled to form a tension member, and a plurality of (26 in the figure) elements made of, for example, aluminum or an aluminum alloy are provided outside the tension member. The wires are arranged as transmission lines and the whole is twisted.

Since the tension member is a composite strand as described above, the wire is light as a whole, and does not cause a large increase in sag even when the wire temperature rises.
Even if the temperature of the wire changes, the tension member does not undergo fatigue fracture, and can be operated for a long period of time.

[0031]

Example: Toyobo Co., Ltd. PBO fiber (linear expansion coefficient:
−6 × 10 ⁻⁶ / ° C.) to form a bundle having a thickness of 2.1 mm. This bundle is composed of a solder (melting point: 32% by weight of Pb, 16% by weight of Sn, and 52% by weight of Bi). : 150
℃), and then cooled, and further introduced into an Al tube having an inner diameter of 5 mm and a wall thickness of 0.2 mm.
The whole was subjected to wire drawing to continuously produce a composite wire having a wire diameter of 3.5 mm.

In this composite strand, PBO fiber, solder,
The volume occupancy of Al was 35%, 15%, and 50%, respectively.
%It has become. Next, seven composite wires were bundled to form a tension member. Twenty-six aluminum conductors having a wire diameter of 4.5 mm were arranged on the outer side of the tension member, and the whole was twisted to obtain the electric wire shown in FIG.

The linear expansion coefficient and the elastic coefficient of the composite wire and the aluminum conductor, and the mass per unit length, the linear expansion coefficient, and the elastic coefficient of the entire electric wire were measured. The results are shown in Table 1. Then, the above electric wire was used for a maximum working tension of 49.0.
It was stretched at a kN of 300 m over a span of 300 m, and the sag at a temperature of 20 ° C., a temperature of 90 ° C., and a temperature of 200 ° C. was measured.

For comparison, seven steel cores having a wire diameter of 3.5 mm are bundled to form a tension member, and 26 aluminum conductors having the same dimensions and characteristics as the above-described aluminum conductor are arranged outside the tension member. A conventional steel core aluminum stranded wire was manufactured. This wire was also subjected to the same sag measurement as in the example, and the results are shown in Table 1.

[0035]

[Table 1]

The following is clear from Table 1. 1) The composite strand of the present invention has a smaller elastic modulus than a steel core and slightly lower strength properties, but has a significantly lower coefficient of linear expansion and a smaller thermal expansion, and therefore, the entire electric wire, This contributes to reducing the coefficient of thermal expansion. 2) When this composite strand is used as a tension member, the strength characteristics of the obtained electric wire are slightly reduced by about 18%, though slightly lower than those of the conventional steel core aluminum wire.

3) In addition, even when the temperature of the electric wire becomes high, the increase in the sag is significantly suppressed as compared with the steel core aluminum stranded wire. Therefore, the load current for transmitting power can be made larger than before.

[0038]

As is apparent from the above description, the composite strand of the present invention is lightweight, has a small coefficient of linear expansion, exhibits an excellent sag suppressing effect at high temperatures, and has a long fiber and a matrix. Since a thermal stress is hardly generated between the material and the fusible metal material, even if it is subjected to a long-term temperature change, fatigue fracture based on the thermal stress does not occur.

Therefore, the overhead transmission line manufactured using the composite strand is light in weight and has a small sag even when the wire temperature rises due to an increase in the load current, and the sag variation hardly occurs. . Therefore, the overhead power transmission line can reduce the load on the tower, and can also lower the tower. In other words, conversely,
Even if the light-weight, low-sagging overhead electric wire of the present invention is connected to an existing steel tower, a larger load current can be applied to the electric wire than before to increase the transmission capacity.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a composite strand of the present invention.

FIG. 2 is a cross-sectional view showing one example of a lightweight low-loose overhead wire of the present invention.

[Explanation of symbols]

 Reference Signs List 1 long fiber 2 fusible metal material 3 copper or aluminum material 4 aluminum conductor

Continued on the front page (72) Inventor Jun Sakagawa 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Atsushi Higashiura 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric (72) Inventor Jiro Hiroishi 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Koichiro Mita 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric (72) Inventor Hiroaki Shiba 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (6)

[Claims] 1. A long fiber is used as a reinforcing material, a fusible metal material in which the long fibers are embedded is used as a matrix, and the outside of the matrix is coated with an aluminum-based or copper-based material. Composite strand. 2. The composite strand according to claim 1, wherein the long fiber is a fiber having a negative coefficient of linear expansion. 3. The composite strand according to claim 1, wherein the long fiber is a polyparaphenylene benzobisoxazole fiber. 4. The fusible metal material has a melting point of 300.
2. The composite strand according to claim 1, wherein the composite strand is a material having a temperature of not more than ℃. 5. The fusible metal material comprises zinc, bismuth,
The composite strand according to claim 1, wherein the composite strand is at least one selected from the group consisting of thallium, tin, and lead, or an alloy thereof. 6. A lightweight, low-sagging overhead electric wire, wherein the bundle of composite strands according to claim 1 is used as a tension member.