JP2014002863A - Steel core aluminum stranded wire and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an increase in wire looseness in accordance with temperature rise during power transmission.SOLUTION: A steel core aluminum stranded wire comprises a steel core part and an aluminum layer formed by twisting a plurality of aluminum wires, installed on the outer periphery of the steel core part, with each other. A predetermined space is formed between the steel core part and the aluminum layer. The aluminum layer has an excess length to the steel core part.

Description

  The present invention relates to a steel core aluminum stranded wire used for an overhead power transmission line and a method for manufacturing the same.

In recent years, as an overhead power transmission line (hereinafter also simply referred to as an electric wire), for example, a steel core portion configured as a galvanized steel stranded wire and a plurality of aluminum strands provided on the outer periphery of the steel core portion are twisted together. A steel core aluminum stranded wire (Aluminum Conductor Steel Reinforced: hereinafter simply referred to as ACSR) provided with a conductor portion is widely used (see, for example, Patent Documents 1 to 6).

JP 2006-318869 A Japanese Patent Publication No.57-17842 JP 2000-353425 A Japanese Patent Laid-Open No. 61-284005 Japanese Examined Patent Publication No. 56-53922 JP 2002-25348 A

  Conventionally, a hard aluminum alloy having a continuous permissible temperature (continuous heat resistance temperature) of 90 ° C. has been adopted as a material for the aluminum wire. However, the continuous permissible temperature of the aluminum element wire is generally proportional to the current capacity of the electric wire. Therefore, in recent years, aluminum alloy materials having higher heat resistance, such as a heat-resistant aluminum alloy having a continuous allowable temperature of 150 ° C., a super heat-resistant aluminum alloy having a continuous allowable temperature of 210 ° C. Is a special heat-resistant aluminum alloy having a temperature of 230 ° C. When these heat-resistant aluminum alloys are employed, the current capacity can be increased without increasing the outer diameter of the electric wire.

  However, even if the heat resistant aluminum alloy described above is adopted as the material of the aluminum wire and the ACSR is configured to withstand power transmission at high temperatures, the slackness (slackness) of the electric wire as the temperature rises during power transmission Since it will become large, it may become difficult to ensure the insulation separation height with the ground or a structure, without rebuilding and raising the existing steel tower.

  An object of the present invention is to provide a steel core aluminum stranded wire capable of suppressing an increase in the slackness of an electric wire accompanying a temperature rise during power transmission and a method for manufacturing the same.

According to a first aspect of the invention,
A steel core aluminum stranded wire comprising: a steel core portion; and an aluminum layer formed by twisting together a plurality of aluminum strands provided on the outer periphery of the steel core portion,
A predetermined gap is provided between the steel core and the aluminum layer,
The aluminum layer is provided with a steel core aluminum stranded wire having a predetermined extra length with respect to the steel core portion.

According to a second aspect of the invention,
Of the aluminum layers, at least a layer adjacent to the steel core is formed by twisting together a plurality of the aluminum strands having cross-sectional shapes that are in surface contact with each other on the side surfaces or fitted to each other. A steel core aluminum stranded wire according to the first aspect is provided.

According to a third aspect of the invention,
In a state where no tension is applied to the steel core portion, the aluminum layer has a surplus length ratio of 0.10% or more with respect to the steel core portion. A steel core aluminum stranded wire is provided.

According to a fourth aspect of the invention,
The surplus length of the aluminum layer is stretched by applying a tension of 50% or less of the breaking load in the length direction to give elastic elongation, and is disposed on the outer periphery of the stretched steel core. The aluminum layer is formed by twisting together a plurality of the aluminum strands, and then the tension applied to the steel core is removed and the steel core is contracted. A steel core aluminum stranded wire according to any one of the first to third aspects is provided.

According to a fifth aspect of the present invention,
The gap provided between the steel core and the aluminum layer is filled with grease that does not soften even when the aluminum layer is heated to a predetermined temperature by power transmission. A steel core aluminum stranded wire according to any of the embodiments is provided.

According to a sixth aspect of the present invention,
Extending the steel core by applying a predetermined tension in the length direction to impart elastic elongation; and
Forming an aluminum layer by twisting together a plurality of aluminum strands arranged with a predetermined gap with respect to the outer periphery of the elongated steel core, and
Removing the tension applied to the steel core and shrinking the steel core to cause the aluminum layer to have a predetermined extra length with respect to the steel core. Is provided.

According to a seventh aspect of the present invention,
In the step of forming the aluminum layer, at least the steel core of the aluminum layer is twisted by twisting together a plurality of the aluminum strands having cross-sectional shapes that are in surface contact with each other or fitted to each other on the side surfaces. The manufacturing method of the steel core aluminum twisted wire as described in the 6th aspect which forms the layer which adjoins a part is provided.

According to an eighth aspect of the present invention,
The steel core according to the sixth or seventh aspect, in which the aluminum layer is caused to have a surplus length ratio of 0.10% or more with respect to the steel core part in a state where the tension applied to the steel core part is removed. A method for producing an aluminum stranded wire is provided.

According to a ninth aspect of the present invention,
In the step of extending the steel core and the step of forming the aluminum layer, the tension applied to the steel core is 50% or less of the breaking load of the steel core. The manufacturing method of the steel core aluminum strand wire as described in 1 is provided.

According to a tenth aspect of the present invention,
After forming the aluminum layer, filling the gap provided between the steel core and the aluminum layer with grease that does not soften even when the aluminum layer is heated to a predetermined temperature by power transmission. A method for producing a steel core aluminum stranded wire according to any one of the sixth to ninth aspects is provided.

  According to the steel core aluminum stranded wire and the method for manufacturing the same according to the present invention, it is possible to suppress an increase in the slackness of the electric wire accompanying a temperature rise during power transmission.

BRIEF DESCRIPTION OF THE DRAWINGS (a) is sectional drawing of the steel core aluminum strand wire which concerns on one Embodiment of this invention, (b) is a figure which illustrates the schematic of a steel core aluminum strand wire, respectively. It is the schematic which illustrates the manufacturing method of the steel core aluminum strand wire which concerns on one Embodiment of this invention. It is the schematic which illustrates the manufacturing apparatus used for the manufacturing method of the steel core aluminum strand wire which concerns on one Embodiment of this invention. It is sectional drawing of the steel core aluminum strand wire which concerns on Example 1 of this invention. It is sectional drawing of the steel core aluminum strand wire which concerns on Example 2 of this invention.

<Knowledge obtained by the inventors>
As described above, even if the heat resistant aluminum alloy is used as the material of the aluminum wire and the ACSR is configured to withstand power transmission at high temperatures, the slackness of the electric wire increases as the temperature rises during power transmission. There was a case. In the conventional ACSR, the tension at the time of overhead wire is shared by both the steel core part and the conductor part. In this case, the linear expansion coefficient of the entire electric wire is, for example, 19 × 10 ^{−6 to} 20 × This is because it was a relatively large value of 10 ⁻⁶ / ° C.

In order to solve the problem, Patent Document 1 discloses a wire (gap-type low-sag increasing capacity wire) in which a gap is provided between the steel core portion and the conductor portion, and the tension applied to the wire is borne only by the steel core portion. Has been proposed. In such a document, the above-mentioned gap is provided, and only the steel core portion is gripped and wired, so that the temperature is higher than the transition point temperature (that is, the temperature at which the wire tension starts to be borne only by the steel core portion). In addition, the linear expansion coefficient of the entire electric wire follows the linear expansion coefficient of the steel core portion of 11.5 × 10 ⁻⁶ / ° C., which can suppress the elongation of the electric wire due to the temperature rise during power transmission and has low sag performance. There is a description that can be given. There is also a description that the slackness of the electric wire can be kept at the same level while increasing the maximum continuous allowable current of the electric wire by about twice. There is also a description that the transition point temperature becomes equal to the overhead wire temperature.

  Patent Document 2 proposes an electric wire (hereinafter simply referred to as an Invar electric wire) that uses an Invar alloy wire obtained by processing an Invar alloy, which is an Fe—Ni alloy having a very small linear expansion coefficient, as a steel core. In such a document, by using an Invar alloy wire for the steel core part, the difference in the coefficient of linear expansion between the steel core part and the conductor part can be increased, and in the temperature region above the transition point temperature, There is a description that the tension shared by the conductor part is zero, and that the overhead wire tension can be borne only by the steel core part, and that the low-sag performance can be imparted to the electric wire. There is also a description that the current capacity of the electric wire can be increased by using a heat-resistant aluminum alloy.

In Patent Documents 3 and 4, elastic tension that can be recovered is applied to the steel core part by applying tension with a wire drawing wheel or the like during manufacturing, and in this state, an aluminum wire is twisted around the steel core part. Together, the conductor part is formed, and then the tension applied to the steel core part is removed to cause each aluminum element wire to have a predetermined extra length with respect to the steel core part. (Pre-stretch electric wires) have been proposed. In these documents, by configuring as a pre-stretch electric wire, it becomes possible to bear the tension that the conductor part shares in the temperature region above the transition point temperature, and to bear the tension at the time of the overhead wire only by the steel core part, There is a description that low sag performance can be imparted to an electric wire.

  In Patent Document 5, after forming a conductor portion formed by twisting a plurality of aluminum strands on the outer periphery of a steel core portion, mechanical stress is applied to the aluminum strand using, for example, a roll. There has been proposed an electric wire (loose type electric wire) that provides elongation due to plastic deformation and provides a gap between a steel core portion and a conductor portion. In such a document, by providing a gap between the steel core part and the conductor part, the tension shared by the conductor part is made zero, so that the tension at the time of the overhead wire can be borne only by the steel core part, and the wire has low relaxation. There is a description that the performance can be imparted.

  Further, Patent Document 6 discloses an electric wire obtained by twisting a hard aluminum wire or soft aluminum wire having plastic elongation around a steel core portion to which elastic elongation is applied or not applied (low A slack increasing capacity electric wire) and a manufacturing method thereof have been proposed.

  However, according to studies by the inventors, it is considered that the electric wires described in these documents have the following problems.

  First, in the gap-type low-sag increasing capacity electric wire described in Patent Document 1, in order to load only the steel core portion with the tension applied to the electric wire and zero the tension shared by the conductor portion, After twisting back the aluminum strand, it is necessary to grip the steel core and perform the tight wire. Furthermore, it is also necessary to twist the aluminum element wire again after leaving it for about 12 hours after tightening. Therefore, the gap-type low-sag increasing capacity electric wire described in Patent Document 1 has problems such as the complexity of the construction associated with the implementation of the special construction method, the lengthening of the construction period, and the increase in overhead construction costs associated therewith. In addition, since work on the tower increases, there is room for improvement in terms of safety.

  Moreover, in the Invar electric wire described in Patent Document 2, since the transition point temperature at which the sharing of the tension is started only with the steel core is as high as 80 to 110 ° C., for example, the temperature range in which the low sag performance can be exhibited is limited. There is a problem of end.

  Moreover, the pre-stretch electric wire described in Patent Documents 3 and 4, the loose electric wire described in Patent Document 5 and the low-sag increasing capacity electric wire described in Patent Document 6 and applying a tension to the steel core Then, when attaching the clamp for tight wire work, the extra length of the aluminum strand to the steel core is exhausted by performing the wrong procedure such as cutting without attaching the jig provided to prevent the extra length from being lost. There is a problem that the low sag performance is lost.

  Moreover, in the loose electric wire described in Patent Document 5 and the low-sag increasing capacity electric wire described in Patent Document 6, since stress is applied to the aluminum element wire using a jig, plastic deformation is applied, There is a problem that nicking (such as generation of scratches) during processing is inevitable and vibration fatigue resistance performance is degraded.

  In addition to suppressing an increase in slack due to a temperature rise during power transmission, the present invention has these technical problems that the electric wires according to the above-mentioned patent document have, that is, simplification of construction at the time of overhead wiring, reduction from a low temperature region. The purpose is to realize at least one of the display of the sag performance, the suppression of the disappearance of the low sag performance when the excess length is exhausted, and the improvement of the vibration fatigue resistance.

<One Embodiment of the Present Invention>
Hereinafter, a steel core aluminum stranded wire (ACSR) and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings.

(Structure of steel core aluminum stranded wire)
First, the structure of the steel core aluminum twisted wire 10 which concerns on this embodiment is demonstrated using FIG. FIG. 1A illustrates a cross-sectional view of a steel core aluminum stranded wire 10 according to this embodiment, and FIG. 1B illustrates a schematic view of the steel core aluminum stranded wire 10.

  The steel core aluminum stranded wire 10 includes a steel core portion 11 and an aluminum layer 12 formed by twisting together a plurality of aluminum strands 13 provided on the outer periphery of the steel core portion 11.

  The steel core part 11 functions so as to bear the tension applied to the electric wire (steel core aluminum stranded wire 10) at the time of the overhead wire. The steel core 11 is a wire material having a tensile strength larger than that of the aluminum strand 13 and a small linear expansion coefficient, for example, a special strong galvanized steel wire having a tensile strength of 1770 MPa or more, and an ultra-strong galvanizing having a tensile strength of 1960 MPa or more. It can be formed using various wire materials such as steel wire, carbon fiber wire, Invar alloy wire, etc., and the surface of these wire materials is covered with aluminum, synthetic resin, carbon fiber, etc. Can be formed. The steel core 11 is not limited to a single wire, but may be formed by twisting a plurality of the above-mentioned wire materials having a circular cross section as shown in FIG. It may be formed by forming a wire material into an arbitrary cross-sectional shape and then twisting a plurality of wires. Further, a plurality of these wire materials can be twisted and then formed using a coated wire material coated with aluminum, synthetic resin, carbon fiber or the like. At this time, there are no restrictions on the number of twisted wires or the cross-sectional shape of the wire material.

  The aluminum layer 12 functions as a conductor portion (portion through which current flows during power transmission) of an electric wire (steel core aluminum stranded wire 10). As the aluminum strand 13 constituting the aluminum layer 12, a wire material having a small specific gravity and a small electric resistance, for example, a hard aluminum wire, a heat resistant aluminum wire, a super heat resistant aluminum wire, a special heat resistant aluminum wire, a high strength heat resistant aluminum alloy wire. Various aluminum wires for power transmission such as No. 1 aluminum alloy wire can be used. The aluminum layer 12 may be formed by twisting a plurality of aluminum strands 13 having a circular cross section, or by twisting a plurality of aluminum strands 13 after forming the above-described aluminum strand 13 into an arbitrary cross-sectional shape. May be formed. At this time, there are no restrictions on the number of twisted wires or the cross-sectional shape of the wire material.

A predetermined gap 14 is provided between the steel core part 11 and the aluminum layer 12. By providing the gap 14, only the steel core 11 can be gripped at the time of overhead wire, the tension shared by the aluminum layer 12 at the time of overhead wire is made zero, and the tension at the time of overhead wire is borne only by the steel core 11. Will be able to. In this way, by imparting tension only to the steel core portion 11 having a small linear expansion coefficient, the steel core aluminum stranded wire 10 can be provided with low sag performance. For the purpose of reliably maintaining the gap 14 between the steel core part 11 and the aluminum layer 12, among the aluminum layers 12, the layer closest to the steel core part 11 (hereinafter also referred to as the aluminum inner layer 12 a). It is preferable to form by twisting a plurality of aluminum wires 13 having cross-sectional shapes that are in surface contact with each other or fitted to each other on the side surfaces. By configuring in this way, deformation (disintegration) of the space formed inside the aluminum inner layer 12a can be prevented, and the gap 14 between the steel core portion 11 and the aluminum layer 12 can be reliably ensured. Become. In addition, the aluminum layer 12 that is not close to the steel core 11 (hereinafter also referred to as the aluminum outer layer 12b) may be formed by twisting a plurality of the above-mentioned wire materials having a circular cross section, You may form by shape | molding the above-mentioned wire material into arbitrary cross-sectional shapes, and twisting together. The gap 14 is preferably filled with grease that does not soften even when the aluminum layer 12 is heated to a predetermined power transmission temperature (for example, a temperature of 90 ° C. or higher). By filling the gap 14 with grease, the frictional resistance between the steel core part 11 and the aluminum layer 12 can be reduced, the steel core part 11 can be easily pulled out, and workability at the time of overhead wire can be improved. become able to. As the grease, various fillers such as mineral oil-based grease and silicon-based grease can be used.

Each of the plurality of aluminum strands 13 constituting the aluminum layer 12 has a predetermined extra length with respect to the steel core portion 11. Even when the aluminum layer 12 has a predetermined extra length, the tension shared by the aluminum layer 12 at the time of overhead wire can be made zero, and the tension at the time of overhead wire can be borne only by the steel core portion 11. In addition, it is preferable that the plurality of aluminum strands 13 constituting the aluminum layer 12 each have a surplus length ratio of 0.10% or more with respect to the steel core portion 11. Specifically, in a state where the steel core aluminum stranded wire 10 is not under tension, when the length of the steel core portion 11 is l _{0 [m],} length of the aluminum layer 12 is 1.001 × l ₀ [M] or more is preferable. As will be described later, the surplus length of the aluminum strand 13 extends and extends the steel core portion 11 by applying a tension of 50% or less of the breaking load in the length direction to give elastic elongation. It can be generated by removing the tension applied to the steel core part 11 after forming the aluminum layer 12 by arranging a plurality of aluminum strands 13 twisted together on the outer periphery of the steel core part 11. .

(Manufacturing method of steel core aluminum stranded wire)
Next, the manufacturing method of the steel core aluminum strand wire 10 mentioned above is demonstrated using FIG.

First, the steel core part 11 is extended by applying a predetermined tension to the steel core part 11 in the length direction to impart elastic elongation. FIG. 2 (a) shows the tension within the elastic limit of the steel core 11 in the length direction (left and right in the figure) with respect to the steel core 11 of length l ₀ [m] (hereinafter referred to as pre-stretch). It shows a state of applying a called load) T _p. The steel core 11 is newly given a length l ₀ (T _p / (E _s · A _s )) due to elastic elongation by applying the above-described tension T _p , and the length is l ₀ (1+ _{(T p / (E s ·} a s)) a [m]. here, _{E s} is the elastic modulus of the steel core portion 11 [N / ^{m 2],} the cross-sectional area of _{a s} are steel core 11 [M ² ].

Next, the aluminum layer 12 is formed on the outer periphery of the steel core portion 11 by twisting together a plurality of aluminum strands 13 arranged with a predetermined gap 14 with respect to the outer periphery of the elongated steel core portion 11. Form. FIG. 2B shows a state in which the aluminum strand 13 is twisted around the steel core 11 in a state where the tension Tp is applied and the layer is extended by l ₀ (T _p / (E _s · A _s )) [m] Thus, the steel core portion 11 elongated to a length l ₀ (1+ (T _p / (E _s · A _s )) [m] and the same length as the elongated steel core portion 11 (ie, l _And an aluminum layer 12 having a length of ₀ (1+ (T _p / (E _s · A _s )) [m]), and a stranded wire (a stranded wire in a state before the tension is removed) is formed. It shows the state.

  Thereafter, as shown in FIG. 2 (c), both ends of the aluminum stranded wire 10 provided with the steel core part 11 and the aluminum layer 12 are fixed by a fixing tool 15 typified by a compression-type sleeve. Take measures to prevent the extra length from being released.

Then, the tension | tensile_strength applied to the steel core part 11 is removed, and the steel core part 11 is contracted, The predetermined extra length with respect to the steel core part 11 is produced in the aluminum layer 12. FIG. That is, after fixing the steel core portion 11 and the aluminum layer 12 in the fastener 15, by removing the pre-stretch load T _p above, steel core portion 11 loses elastic elongation, its length is returned to l ₀ . On the other hand, since the length of the aluminum layer 12 remains (1+ (T _p / (E _s · A _s )), the aluminum layer 12 is formed on the steel core 11 as shown in FIG. On the other hand, the steel core aluminum stranded wire 10 according to the present embodiment is manufactured by the above-described steps, with a surplus length corresponding to T _p / (E _s · A _s ) [m].

  As described above, a plurality of aluminum elements having a cross-sectional shape in which the steel core portion 11 is in contact with each other on the side surfaces or fitted to each other immediately on the outer side while applying a tension that does not cause plastic deformation. By twisting the wire 13 while providing a predetermined gap 14 between the steel core portion 11 and having a low sag performance equal to or higher than that of a conventional gap-type low sag increasing capacity electric wire, the workability and the like are improved. An excellent steel core aluminum stranded wire 10 can be obtained.

  In addition, in order to improve the low sag performance of the steel core aluminum stranded wire 10, it is necessary to manage the tension applied to the steel core portion 11 at the time of manufacture, that is, the aluminum strand 13 to the steel core portion 11. It is extremely important to manage the excess length ratio. When an excessive tension exceeding the elastic limit is applied to the steel core part 11, the steel core part 11 is plastically deformed, and the load resistance performance of the steel core aluminum stranded wire 10 may be reduced. If the tension applied to the steel core portion 11 is too small, a sufficient extra length cannot be generated in the aluminum layer 12, and the low sag performance of the steel core aluminum stranded wire 10 may be reduced.

  In general, the tension applied to the steel core aluminum stranded wire under normal tension conditions is approximately 20% of the breaking load, although it depends on the distance between steel towers (so-called span length) and the geographical conditions. In a general steel core aluminum stranded wire in which the tension is shared by both the steel core portion and the conductor portion, when a tension of 20% of the breaking load is applied to the steel core aluminum stranded wire, It is considered that a tension of 30 to 50% of the breaking load is applied. In the steel core aluminum stranded wire 10 according to the present embodiment, the steel core portion 11 bears all the loads applied to the electric wires above the transition point temperature. Therefore, in the present embodiment, in order to prevent the load bearing performance of the steel core aluminum stranded wire 10 from being deteriorated due to plastic deformation of the steel core part 11, the tension applied to the steel core part 11 at the time of manufacture is broken. It is necessary to make it 50% or less of the load. That is, within that range, it is necessary to apply to the steel core 11 a tension that produces a surplus length sufficient for the shared tension of the aluminum layer 12 to become zero.

  On the other hand, although the surplus length is sufficient for the shared tension of the aluminum layer 12 to be zero, the inventors have experimentally determined that the surplus length ratio of the aluminum layer 12 to the steel core portion 11 is at least 0.10% or more. For example, it has been confirmed that the shared tension of the aluminum layer 12 at the time of the overhead wire is sufficient to reach zero.

  Therefore, in the present embodiment, the prestretch load (tension during manufacture) applied to the steel core 11 is set to 50% or less of the breaking load of the steel core 11 while being applied to the aluminum layer 12. Preferably, the upper limit and the lower limit are determined and adjusted so that the remaining length ratio is 0.10% or more with respect to the steel core portion 11.

(Configuration of twisted wire manufacturing equipment)
In FIG. 3, the manufacturing apparatus 20 used for the manufacturing method of the steel core aluminum twisted wire 10 which concerns on this embodiment is illustrated for reference.

As shown in FIG. 3, the manufacturing apparatus 20 suitably used in the present embodiment includes a payoff (feeder) 21 that feeds the wound steel core part 11, and a prestretch load T on the fed steel core part 11. the extending line wheel 22 as the tensioning means for loading the _p, a pressure pump 23 for filling the grease in the gap 14 provided between the steel core 11 and the aluminum layer 12, pre-stretch load T _p is the load A stranded wire machine 24a that twists the aluminum wire 13 around the steel core 11 to form the aluminum inner layer 12a, and a stranded wire machine 24b that twists the aluminum wire 13 around it to form the aluminum outer layer 12b. And a double capstan 25 as a tension load means for generating a predetermined tension between the wire drawing wheel 22 and the steel core aluminum stranded wire 10 after being manufactured. A winding machine 26, and a.

Pre-stretch load T _p is applied between the extended line wheel 22 and a double capstan 25, between the extended line wheel 22 and strander 24a, the applied tension to the steel core 11 A tension meter 27 for measuring is provided.

  The combination of the wire drawing wheel 22 and the double capstan 25 shown in FIG. 3 can be considered as a typical tension load means, but the pre-stretch load required for the steel core portion 11 is applied. A manufacturing apparatus having another configuration may be used as long as it can be stably applied.

  Since the tension applied to the steel core portion 11 is exhausted by passing through the double capstan 25 and being taken up by the winder 26, both ends of the steel core aluminum stranded wire 10 are compressed before passing through the double capstan 25. By tying with the fixing tool 15 typified by the sleeve, it is possible to obtain a stranded wire that is held without releasing the extra length of the aluminum strand 13 with respect to the steel core portion 11. In addition, this fixing tool 15 is not limited to a compression-type sleeve, For example, you may use a clamp etc.

  Further, in order to prevent so-called laughter (local loosening of the strands constituting the electric wire) from occurring due to the extra length of the aluminum strand 13 being moved and gathered at one place during the winding operation or the wire drawing operation. If necessary, a plurality of the above-described fixing tools 15 may be attached to an intermediate portion other than the end of the steel core aluminum stranded wire 10 at an arbitrary quantity and an arbitrary interval.

(Effect according to this embodiment)
According to the present embodiment, one or a plurality of effects shown below are produced.

(A) The steel core aluminum stranded wire 10 according to the present embodiment has a predetermined gap 14 between the steel core portion 11 and the aluminum layer 12. Furthermore, the aluminum layer 12 has a predetermined extra length with respect to the steel core part 11. The steel core aluminum stranded wire 10 configured in this way is held by holding only the steel core portion 11 while maintaining the surplus length of the aluminum layer 12, thereby reducing the tension shared by the aluminum layer 12 to the overhead wire. It becomes possible to load only the steel core 11 with the tension at the time. As a result, the elongation of the steel core aluminum stranded wire 10 due to the temperature rise accompanying power transmission can be made to depend only on the linear expansion coefficient of the steel core portion 11, and the steel core aluminum stranded wire 10 has low sag characteristics. Can be granted.

(B) By transitioning the steel core aluminum stranded wire 10 according to this embodiment while maintaining the surplus length of the aluminum layer 12, the transition point temperature can be lowered (for example, about the same as the temperature at the time of overhead wire). For example, compared with the Invar electric wire etc. which were described in patent document 2, a low sag characteristic can be acquired from a low temperature area | region. That is, the transition point temperature of the steel core aluminum stranded wire 10 according to the present embodiment depends on the atmospheric temperature at the time of manufacture and the tension applied at the time of manufacture, and therefore, from 80 ° C. to 110 ° C. which is the transition point temperature of the Invar wire. Can be set to a low temperature, and the above-mentioned low sag characteristic can be obtained from a lower temperature region.

(C) According to the present embodiment, a plurality of aluminum strands having a cross-sectional shape in which at least the layers close to the steel core portion 11 of the aluminum layer 12 are in surface contact with each other on the side surfaces or are mutually fitted. 13 are twisted together. Thereby, the gap 14 between the steel core part 11 and the aluminum layer 12 is ensured, and the low sag characteristic can be obtained more reliably.

(D) According to the present embodiment, the aluminum layer 12 is not less than 0.10% with respect to the steel core portion 11 in a state where no tension is applied to the steel core aluminum stranded wire 10 (steel core portion 11). Has a surplus length ratio. Thereby, the above-described low sag characteristic can be more reliably exhibited.

(E) According to this embodiment, when the steel core aluminum stranded wire 10 is manufactured, the tension applied to the steel core part 11 is set to 50% or less of the breaking load of the steel core part 11. Therefore, plastic deformation of the steel core part 11 can be prevented, and a decrease in load bearing performance of the steel core aluminum stranded wire 10 can be prevented.

(F) When the gap type low-sag increasing electric wire described in Patent Document 1 is used by laying the steel core aluminum stranded wire 10 according to the present embodiment while maintaining the surplus length of the aluminum layer 12 Therefore, it is possible to omit the tension release work after the tight connection necessary for the cable. In other words, there is no need for tension release work such as untwisting, retwisting the aluminum wire during overhead wire work, and leaving it for 12 hours after overhead wire on the tower, shortening the work time in high places, shortening the construction period, and reducing the cost. An advantageous effect in terms of safety can be obtained. In addition, in order to carry out the overhead wire while maintaining the surplus length of the aluminum layer 12, when cutting the steel core aluminum stranded wire 10, the fasteners 15 are attached to both ends of the cut portion so that the surplus length of the aluminum strand 13 is not opened. Only one procedure of attaching in advance is increased, and the workability can be said to be equal to or higher than that of the pre-stretch electric wire described in Patent Documents 3 and 4, for example.

(G) The steel core aluminum stranded wire 10 according to the present embodiment is converted into a normal gap-type low-sag wire at the time of wire-tightening even when the surplus length of the aluminum layer 12 is exhausted for some reason. By performing an operation similar to the operation performed on the aluminum wire (tension releasing operation on the aluminum strand), it is possible to impart low sag performance again. Therefore, the steel core aluminum stranded wire 10 according to the present embodiment includes a pre-stretch electric wire described in Patent Literatures 3 and 4, a loose electric wire described in Patent Literature 5 and a low sag increase described in Patent Literature 6. There is an advantage that mistakes at the time of construction do not immediately become defective when compared with electric wires etc. that are capacitative wires and tension is applied to the steel core.

  In this case, the workability in the overhead wire work can be improved by filling the gap 14 provided between the steel core part 11 and the aluminum layer 12 with grease. That is, by filling the gap 14 with grease, the frictional resistance between the steel core part 11 and the aluminum layer 12 can be reduced, the steel core part 11 can be easily pulled out, and the workability in the above-described tension releasing operation is improved. Can be improved. The gap 14 is filled with grease that does not soften even when the aluminum layer 12 is heated to a predetermined temperature (power transmission temperature), thereby preventing the grease from flowing out of the gap 14 at the time of temperature increase. I can do it.

(H) According to this embodiment, when the steel core aluminum stranded wire 10 is manufactured, the aluminum strand 13 is not plastically deformed. Therefore, the steel core aluminum stranded wire 10 according to the present embodiment has high vibration fatigue resistance compared to, for example, the loose wire described in Patent Document 5 and the low-sag increased capacity wire described in Patent Document 6. have.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, It can change variously in the range which does not deviate from the summary.

FIG. 4 is a cross-sectional view of the steel core aluminum stranded wire 10 according to the first embodiment of the present invention. The steel core aluminum stranded wire 10 according to Example 1 is similar to the above-described embodiment in that the steel core portion 11 is located in the center, and the aluminum inner layer 12a is disposed with a gap 14 provided on the outer periphery of the steel core portion 11. And an aluminum outer layer 12b disposed so as to be in contact with the outer periphery of the aluminum inner layer 12a. An aluminum layer 12 as a conductor portion is formed by the aluminum inner layer 12a and the aluminum outer layer 12b. The gap 14 is filled with a filler such as grease having a predetermined viscosity coefficient.

  The steel core part 11 is formed by twisting together strands such as a plurality (here, seven) of special strong galvanized steel wires, and is configured to share overhead wire tension. A pre-stretch load 28910 [N] (33% of the breaking load of the steel core 11 and 20.9% of the breaking load of the steel core aluminum stranded wire 10) is applied to the steel core 11 at the time of manufacture. And

  The aluminum inner layer 12 a is formed by twisting together a plurality of aluminum strands 13 having a fan-shaped cross section or a trapezoidal cross section that are in surface contact with each other on the side surface, and is disposed as the innermost layer of the aluminum layer 12. In Example 1, the aluminum wire 13 constituting the aluminum inner layer 12a is made of a special heat-resistant aluminum alloy, and as shown in Table 7 of the Japan Electrical Wire Manufacturers Association Standard JCS0374 “Calculation Standard for Bare Wire Allowable Current”. It has a temperature of 210 ° C.

  The aluminum outer layer 12 b is formed by twisting a plurality of aluminum strands 13 having a circular cross section, and is disposed as the outermost layer of the aluminum layer 12. In the first embodiment, the aluminum wire 13 constituting the aluminum outer layer 12b is made of a special heat-resistant aluminum alloy in the same manner as the aluminum wire 13 constituting the aluminum inner layer 12a.

  The transition point temperature of the steel core aluminum stranded wire 10 according to Example 1 is calculated as 20 ° C. according to the following formula when the manufacturing temperature is 30 ° C. This can be said to be equivalent to the transition point temperature (equivalent to the outside air temperature at the time of close connection) equivalent to the existing gap-type increased capacity wire.

_{T p (t) = T p30} + E s · A s (α a -α s) (t-30)
However,
T _p (t): Pre-stretch load at a temperature of t ° C. [N]
T _p30 : Pre-stretch load at a temperature of 30 ° C. [N]
E _s : Elastic modulus of steel core [N / m ₂ ]
A _s: cross-sectional area of the steel core portion _[m 2]
α _s : Linear expansion coefficient of steel core (= 11.5 × 10 ⁻⁶ / ° C.)
α _a : Linear expansion coefficient of aluminum (= 23.0 × 10 ⁻⁶ / ° C.)
t: Transition temperature [° C]

  Table 1 shows calculation results of allowable current values and catenary approximations performed for the steel core aluminum stranded wire according to Comparative Example 1 (commonly called “ADR”) and the steel core aluminum stranded wire 10 according to Example 1. The results of calculation of the sag by are shown respectively. Table 1 is calculated based on the calculation standard described in JCS0374, and the calculation conditions are as follows.

Current capacity calculation condition (JCS0374 recommended value)
Ambient temperature 40 ℃
Wind speed 0.5m / s
Solar radiation 0.1 W / cm ²
Emissivity of wire surface (emissivity) η 0.9
Wind direction angle 45 °

Sag-tension calculation condition (catenari approximation)
Ambient temperature 20 ℃
Overhead tension 27620N
Wind speed 0.0m / s
Icing snow thickness 0.0mm
Span length 350m
Manufacturing temperature 30 ° C
Pre-stretch load 28910N
Transition temperature 20 ° C

  As is apparent from Table 1, the steel core aluminum stranded wire 10 of Example 1 using a super heat-resistant aluminum alloy wire as the aluminum strand 13 was about twice as large as that of Comparative Example 1 at 210 [° C.]. While having a current capacity, the sag at the maximum continuous permissible current is suppressed to the same extent. Moreover, since both mass and an outer diameter are smaller than the comparative example 1, the load added to a steel tower can also be made small.

  A calculation example of the extra length ratio of the aluminum layer 12 performed on the steel core aluminum stranded wire 10 according to Example 1 is shown below.

Is In steel core aluminum stranded wire 10 according to Embodiment ^{_{1, E s = 205.9 [N}} / m 2], a ^{A s = 49.48 [m 2]} , pre-stretch applied to the steel core 11 Since the load is 28910 [N], which is 33% of the breaking load of the steel core portion 11, the length of the steel core aluminum stranded wire 10 is 1. by the above-described formula l ₀ (Tp / (Es · As)). 0028 × _l is 0 [m], the excess length of the aluminum layer 12 for the steel core portion 11 the tension has been removed is 0.28%.

  In the steel core aluminum stranded wire 10 according to the first embodiment, since the aluminum layer 12 has an extra length with respect to the steel core portion 11 in the overhead wire state, the aluminum inner layer 12a and the aluminum outer layer 12b have an overhead wire tension. All overhead wire tension is applied only to the steel core 11 without being applied. Therefore, the temperature elongation of the steel core aluminum stranded wire 10 according to the first embodiment is not affected by the linear expansion coefficient of the aluminum strand 13 and is determined only by the linear expansion coefficient of the steel core portion 11, and therefore, a general ACSR As compared with, the increase in slack with temperature rise can be greatly reduced.

In Example 1, although the super heat-resistant aluminum alloy strand was used as the aluminum strand 13, and the example which formed the steel core part 11 with the galvanized steel wire was demonstrated, various other Examples and modifications can be considered. . For example, as the aluminum strand 13, a heat resistant aluminum alloy strand or a high strength heat resistant aluminum alloy strand may be used instead of the super heat resistant aluminum alloy strand. Moreover, the steel core part 11 may be an electric wire formed of an aluminum-clad steel wire, a zinc-aluminum-plated steel wire, a synthetic resin, its stranded wire, carbon fiber, and its stranded wire instead of the galvanized steel wire. Further, the aluminum layer 12 may have a laminated structure of three or more layers. Moreover, you may use the wire material which has the shape of the fan-shaped cross section or the trapezoidal cross section as the aluminum strand 13 which forms the layer after the 2nd layer. Thus, the present invention can be implemented with various materials without departing from the spirit of the present invention.

  FIG. 5 is a cross-sectional view of a steel core aluminum stranded wire 10 according to Example 2 of the present invention. The steel core aluminum stranded wire 10 according to Example 2 is arranged with the steel core part 11 positioned at the center and the gap 14 provided on the outer periphery of the steel core part 11 as in the above-described embodiment and Example 1. The aluminum inner layer 12a and the aluminum outer layer 12b arranged so as to contact the outer periphery of the aluminum inner layer 12a are provided. An aluminum layer 12 as a conductor portion is formed by the aluminum inner layer 12a and the aluminum outer layer 12b. The gap 14 is filled with a filler such as grease having a predetermined viscosity coefficient.

  The steel core 11 is formed, for example, by twisting a plurality (here, seven) of aluminum-covered Invar alloy strands, and is configured to handle overhead wire tension. A pre-stretch load 13830 [N] (33% of the breaking load of the steel core 11 and 17.8% of the breaking load of the steel core aluminum stranded wire 10) is applied to the steel core 11 at the time of manufacture. And

  The aluminum inner layer 12 a is formed by twisting together a plurality of aluminum strands 13 having a fan-shaped cross section or a trapezoidal cross section that are in surface contact with each other on the side surface, and is disposed as the innermost layer of the aluminum layer 12. In Example 2, the aluminum strand 13 constituting the aluminum inner layer 12a is made of a heat-resistant aluminum alloy, and as shown in Table 7 of the Japan Electrical Wire Manufacturers Association Standard JCS0374 “Calculation Standard for Bare Wire Allowable Current”. 150 ° C.

  The aluminum outer layer 12 b is formed by twisting a plurality of aluminum strands 13 having a trapezoidal cross section, and is disposed as the outermost layer of the aluminum layer 12. In the second embodiment, the aluminum wire 13 constituting the aluminum outer layer 12b is made of a heat-resistant aluminum alloy in the same manner as the aluminum wire 13 constituting the aluminum inner layer 12a.

  In Table 2, the steel core aluminum stranded wire according to Comparative Example 2 (commonly called “HAWK” ACSR), the steel core aluminum stranded wire according to Comparative Example 3 (having an aluminum conductor cross-sectional area equivalent to that of Comparative Example 2, TACIR, which is a heat-resistant aluminum stranded wire having an aluminum-covered invar core, commonly referred to as “HAWK”), and a calculation result of allowable current values performed on the steel core aluminum stranded wire 10 according to Example 2 and a catenary approximation The calculation results of sag and their respective values are shown. Table 2 is calculated based on the calculation standard described in JCS0374, and the calculation conditions are as follows.

Current capacity calculation condition (JCS0374 recommended value)
Ambient temperature 40 ℃
Wind speed 0.5m / s
Solar radiation 0.1 W / cm ²
Emissivity of wire surface (emissivity) η 0.9
Wind direction angle 45 °

Sag-tension calculation condition (catenari approximation)
Ambient temperature 20 ℃
Overhead wire tension 20% of the minimum tensile load of each wire
ACSR 16400N
TACIR 17960N
Electric wire 15500N of Example 2
Wind speed 0.0m / s
Icing snow thickness 0.0mm
Span length 350m
Manufacturing temperature 30 ° C
Pre-stretch load 13830N

  As is apparent from Table 2, in Comparative Example 3 (TACIR “HAWK”) configured as an Invar wire, the maximum continuous allowable current increased 1.6 times compared to Comparative Example 2 (ACSR “HAWK”). However, it is suppressed to the same degree of sag under the above conditions. However, the overhead wire tension is 1,560 [N], the mass is about 10%, the outer diameter is increased by 0.62 [mm], and the load on the steel tower increases. Therefore, reinforcement or raising is necessary depending on the steel tower strength. There are cases where

  On the other hand, the steel core aluminum stranded wire 10 according to Example 2 has a maximum allowable current capacity equivalent to that of Comparative Example 3 (TACIR “HAWK”), but has a mass compared to Comparative Example 2 (ACSR “HAWK”). Is kept at an increase of about 1.3%, the overhead wire tension is reduced by 900 [N], the outer diameter is reduced by 0.78 [mm], and the load on the steel tower is the same. Further, the sag at the maximum continuous permissible current is also 0.8 [m] compared with Comparative Example 2 (ACSR “HAWK”) and compared with Comparative Example 3 (TACIR “HAWK”) under the above-mentioned conditions. Therefore, it is possible to simply replace the comparative example 2 (ACSR “HAWK”) with the steel core aluminum stranded wire 10 according to the example 2 without rebuilding the steel tower. Become. The decrease in the sag is because the transition point temperature is shifted to 64 ° C. to the lower temperature side than the conventional Invar wire, and the low sag effect is exhibited from a lower temperature region.

  A calculation example of the extra length ratio of the aluminum layer 12 performed on the steel core aluminum stranded wire 10 according to Example 2 is shown below.

Is In steel core aluminum stranded wire 10 according to Embodiment ^{_{2, E s = 152.0 [N}} / m 2], a ^{A s = 43.11 [m 2]} , pre-stretch applied to the steel core 11 since the load is 30% of the breaking load of the steel core portion 11 13830 [N], the equation _l 0 described previously (Tp / (Es · as) ), the length of the steel core aluminum stranded wire 10 1. 0021 × _l is 0 [m], the excess length of the aluminum layer 12 for the steel core portion 11 the tension has been removed is 0.21%.

  In the steel core aluminum stranded wire 10 according to the second embodiment, similarly to the first embodiment, the aluminum layer 12 has an extra length with respect to the steel core portion 11 in the overhead wire state. No overhead wire tension is applied to 12b, and all overhead wire tensions are applied only to the steel core portion 11. Accordingly, the temperature elongation of the steel core aluminum stranded wire 10 according to the second embodiment is not affected by the linear expansion coefficient of the aluminum element wire 13 and is determined only by the linear expansion coefficient of the steel core portion 11. In comparison, an increase in slack with a rise in temperature can be greatly reduced.

  In Example 2, although the example which used the heat-resistant aluminum alloy strand as the aluminum strand 13 and formed the steel core part 11 with the aluminum covering invar alloy wire was described, various other Examples and modifications can be considered. . For example, as the aluminum wire 13, a super heat-resistant aluminum alloy wire or a high-strength heat-resistant aluminum alloy wire may be used instead of the heat-resistant aluminum alloy wire. Moreover, you may form the steel core part 11 with an aluminum covering steel wire, a zinc aluminum plating steel wire, a synthetic resin, its stranded wire, carbon fiber, and its stranded wire instead of an aluminum covering invar alloy wire. Further, the aluminum layer 12 may have a laminated structure of three or more layers. Moreover, you may use the wire material which has the shape of the fan-shaped cross section or the trapezoidal cross section as the aluminum strand 13 which forms the layer after the 2nd layer. Thus, the present invention can be implemented with various materials without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Steel core aluminum strand wire 11 Steel core part 12 Aluminum layer 13 Aluminum strand 14 Space | gap

Claims (10)

A steel core aluminum stranded wire comprising: a steel core portion; and an aluminum layer formed by twisting together a plurality of aluminum strands provided on the outer periphery of the steel core portion,
A predetermined gap is provided between the steel core and the aluminum layer,
The aluminum layer has a predetermined extra length with respect to the steel core portion. Of the aluminum layers, at least a layer adjacent to the steel core is formed by twisting together a plurality of the aluminum strands having cross-sectional shapes that are in surface contact with each other on the side surfaces or fitted to each other. The steel core aluminum stranded wire according to claim 1, wherein The aluminum layer has a surplus length ratio of 0.10% or more with respect to the steel core portion in a state where no tension is applied to the steel core portion. Steel core aluminum stranded wire as described in 1. The surplus length of the aluminum layer is stretched by applying a tension of 50% or less of the breaking load in the length direction to give elastic elongation, and is disposed on the outer periphery of the stretched steel core. The aluminum layer is formed by twisting together a plurality of the aluminum strands, and then the tension applied to the steel core is removed to cause the steel core to contract. The steel core aluminum stranded wire according to any one of claims 1 to 3. The gap provided between the steel core and the aluminum layer is filled with grease that does not soften even when the aluminum layer is heated to a predetermined temperature by power transmission. The steel core aluminum stranded wire according to any one of 1 to 4. Extending the steel core by applying a predetermined tension in the length direction to impart elastic elongation; and
Forming an aluminum layer by twisting together a plurality of aluminum strands arranged with a predetermined gap with respect to the outer periphery of the elongated steel core, and
A step of removing a tension applied to the steel core portion and causing the steel core portion to contract to cause the aluminum layer to have a predetermined extra length with respect to the steel core portion. A method of manufacturing a stranded wire. In the step of forming the aluminum layer, at least the steel core of the aluminum layer is twisted by twisting together a plurality of the aluminum strands having cross-sectional shapes that are in surface contact with each other or fitted to each other on the side surfaces. The method of manufacturing a steel core aluminum stranded wire according to claim 6, wherein a layer close to the portion is formed. The excess length ratio of 0.10% or more is generated in the aluminum layer with respect to the steel core portion in a state where the tension applied to the steel core portion is removed. Manufacturing method for steel core aluminum stranded wire. In the step of extending the steel core and the step of forming the aluminum layer, the tension applied to the steel core is 50% or less of the breaking load of the steel core. The manufacturing method of the steel core aluminum strand wire in any one of. After forming the aluminum layer, filling the gap provided between the steel core and the aluminum layer with grease that does not soften even when the aluminum layer is heated to a predetermined temperature by power transmission. The method for producing a steel core aluminum stranded wire according to any one of claims 6 to 10, wherein:

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