JP2013040387A - Twisted wire and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a twisted wire that has softness relative to a twisted wire formed of a tough pitch copper even when work hardening is caused therein during wire twisting process, and to provide a method for manufacturing the same.SOLUTION: The method for manufacturing the twisted wire includes: a hard drawn copper wire producing step where a dilute copper alloy wire containing copper with inevitable impurities, more than 2 mass ppm. oxygen, and at least one additive element of Mg, Zr, Nb, Ca, V, N, Mn, Ti and Cr is subjected to wire drawing with at least 50% processing degree so that a hard drawn copper wire is produced at the final wire diameter; a twisted wire producing step where a plurality of the hard drawn copper wires are twisted to produce the twisted wire; and a preheating step where the twisted wire is subjected to preheating to alter the hard drawn copper into an annealed copper wire.

Description

  The present invention relates to a stranded wire mainly composed of copper as a material and a method for producing the same.

  As a conventional technique, there is known a method for manufacturing a conductor in which a copper alloy rough wire is drawn to a predetermined diameter to produce a hard copper wire, and the annealed hard copper wire is annealed to produce a soft copper wire. (For example, refer to Patent Document 1).

  The conventional method for producing a conductor requires an annealing process to obtain an annealed copper wire, and the hardness of the conductor is determined by this annealing process. In addition, as a material for conventional annealed copper wire, tough pitch copper is generally used from the viewpoint of low cost.

  Moreover, the conventional CV cable uses a twisted wire so as to have bending characteristics.

  In the conventional method for producing a stranded wire, in a wire drawing process, a hard copper wire drawn to a desired wire diameter is annealed by energization heat generation using a current-carrying annealer to form a soft copper wire as a stranded wire in a stranded wire process. To do. This method is a production method that has been put to practical use as a method for producing an annealed copper wire, and is excellent in productivity in that an in-line operation is possible.

JP 11-224538 A

  However, on the other hand, at the time of stranded wire processing in the stranded wire process, work hardening of the annealed copper wire proceeds and there is a problem that a stranded wire having desired softness cannot be obtained.

  In addition, some of the stranded wires are subjected to mild compression processing in order to adjust the cross-sectional shape of the stranded wire after the stranded wire processing, but this compression processing may add work hardening to the stranded wire. In addition, there is a problem that a stranded wire having desired softness cannot be obtained.

  In this way, when the cable is not flexible, workability becomes very poor when routing inside the building or outdoors. A soft cable can maintain its bent shape even when bent and routed, but if a hard cable is used, it will remain straight even when bent into the routed shape. Because it tries to come back, there is a risk of hitting a person or an object when trying to return to its original form, and a soft cable is required.

  Accordingly, an object of the present invention is to provide a stranded wire having a softness as compared with a stranded wire made of tough pitch copper and a method for producing the same even if work hardening occurs in the stranded wire process in order to solve the above problems. It is in.

In order to achieve the above object, the present invention adds copper containing inevitable impurities, oxygen in an amount exceeding 2 mass ppm, and at least one addition of Mg, Zr, Nb, Ca, V, N, Mn, Ti, and Cr. A dilute copper alloy wire containing an element, and a hard copper wire production step of producing a hard copper wire by performing a drawing process with a workability of 50% or more so as to be a final wire diameter;
Preparing a plurality of the hard copper wires and twisting them together to produce a stranded wire; and
A preheating step of pre-heat-treating the stranded wire to transform the hard copper wire into an annealed copper wire;
It is the manufacturing method of the twisted wire characterized by including.

Further, the present invention is a dilute solution containing copper containing inevitable impurities, oxygen in an amount exceeding 2 mass ppm, and at least one additive element of Mg, Zr, Nb, Ca, V, N, Mn, Ti, and Cr. A hard copper wire preparation step of producing a hard copper wire by subjecting the copper alloy wire to a final wire diameter of 50% or more to draw a hard copper wire;
Preparing a plurality of the hard copper wires and twisting them together to produce a stranded wire; and
A preheating step of pre-heat-treating the stranded wire to transform the hard copper wire into an annealed copper wire;
A coating step of coating the outer periphery of the stranded wire with a resin;
It is the manufacturing method of the insulated wire characterized by having provided.

  The additive element added to copper containing inevitable impurities is titanium of 4 mass ppm or more and 55 mass ppm or less, and copper containing inevitable impurities is sulfur of 2 mass ppm or more and 12 mass ppm or less and more than 2 mass ppm and less than 30 mass ppm or less. Of oxygen.

  The present invention can realize a stranded wire having softness as compared with a stranded wire made of tough pitch copper even if work hardening occurs in the stranded wire process.

It is the schematic of the cable which concerns on the Example of this invention. It is a figure which shows the relationship between the heat processing conditions and the Vickers hardness of the implementation material 1 of this invention and the comparative material 1 which were produced with the conventional construction method. It is a figure which shows the relationship between the heat processing conditions of the implementation material 2 of this invention and the comparative material 2 which were produced with the manufacturing method of this invention, and Vickers hardness. It is a figure which shows the relationship between the heat processing conditions and the Vickers hardness of the implementation material 3 of this invention and the comparative material 3 which were produced with the conventional construction method. It is a figure which shows the relationship between the heat processing conditions of the implementation material 4 of this invention and the comparative material 4 which were produced with the manufacturing method of this invention, and Vickers hardness. It is a figure which shows the relationship between the heat processing conditions of the implementation material 5 of this invention and the comparative material 5 which were produced by the conventional construction method, and Vickers hardness. It is a figure which shows the relationship between the heat processing conditions of the implementation material 6 of this invention and the comparison material 6 which were produced with the manufacturing method of this invention, and Vickers hardness.

  A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 shows a schematic diagram of a cable 1 to which a stranded wire of the present invention and a manufacturing method thereof are applied.

  The cable 1 includes a conductor 2 and an insulated wire 4 having an insulator 3 that covers a stranded wire formed from a plurality of conductors 2 and a sheath 5 that covers the insulated wire 4.

  The manufacturing method of the conductor 2 which consists of this twisted wire is produced in the following processes.

  First, a dilute copper alloy wire comprising copper containing inevitable impurities, oxygen in an amount exceeding 2 mass ppm, and at least one additive element of Mg, Zr, Nb, Ca, V, N, Mn, Ti, and Cr Is subjected to wire drawing so as to be the final wire diameter to produce a hard copper wire (hard copper wire production step).

  Next, a hard copper wire is twisted together to produce a stranded wire (twisted wire process).

  This stranded wire is put into an annealing furnace and transformed into annealed copper wire (annealing step).

  The conductor 2 is manufactured by the above process, and the outer periphery of the conductor 2 is coated with a resin to form an insulator 3 to form an insulated wire 4, and the outer periphery of the insulated wire 4 is covered with a sheath 5 so that the cable 1 It is said.

  Next, the structure of the conductor used for the stranded wire which concerns on this Embodiment is demonstrated.

(1) About additive element The conductor used for the CV cable etc. which concern on this Embodiment contains the additive element selected from the group which consists of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr. A soft dilute copper alloy material with the balance being copper and inevitable impurities.

  The reason for selecting an element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr as an additive element is that these elements are easily active elements that are easily combined with other elements. This is because S can be trapped because it is easily combined with S, and the copper base material (matrix) can be highly purified and the hardness of the material can be reduced. One or more additive elements may be included. Also, other elements and impurities that do not adversely affect the properties of the alloy can be included in the alloy.

Further, in the preferred embodiment described below, it is explained that the oxygen content is better than 2 mass ppm and 30 mass ppm or less, but depending on the addition amount of the additive element and the S content, In the range provided with the property of an alloy, it can contain more than 2 mass ppm and 400 mass ppm.

(2) About composition ratio Since the twisted wire which concerns on this Embodiment is used as an electroconductive material, a thing with higher electroconductivity is preferable.

For example, the horizontal winding according to the present embodiment has a conductivity of 98% IACS (conductivity when the universal annealed copper standard is more than 100% and the resistivity 1.7241 × 10 ⁻⁸ Ωm is 100%). It is preferable to use a soft dilute copper alloy material as a soft copper material that satisfies 100% IACS or more, more preferably 102% IACS or more.

  When obtaining a soft copper material having an electrical conductivity of 98% IACS or more, as pure copper (base material) containing inevitable impurities, 3 to 12 mass ppm of sulfur, 2 mass ppm to more than 30 mass ppm of oxygen, and 4 to 55 mass ppm A soft dilute copper alloy material containing titanium is used, and a wire rod (rough drawing wire) is manufactured from the soft dilute copper alloy material.

  Here, when obtaining a soft copper material having an electrical conductivity of 100% IACS or higher, as pure copper (base material) containing inevitable impurities, 2 to 12 mass ppm of sulfur, 2 mass ppm to oxygen and 30 mass ppm or less of oxygen A soft dilute copper alloy material containing 4-37 mass ppm titanium is used.

  Further, when obtaining a soft copper material having an electrical conductivity of 102% IACS or more, as pure copper (base material) containing inevitable impurities, 3 to 12 mass ppm of sulfur, more than 2 mass ppm and oxygen of 30 mass ppm or less, A soft dilute copper alloy material containing 4 to 25 mass ppm of titanium is used.

  Usually, in the industrial production of pure copper, sulfur is taken into copper when producing electrolytic copper. Therefore, it is difficult to reduce sulfur to 3 mass ppm or less. The upper limit of the sulfur concentration of general-purpose electrolytic copper is 12 mass ppm.

  In this embodiment, so-called low oxygen copper (LOC) is targeted because it contains oxygen exceeding 2 mass ppm and not more than 30 mass ppm.

  When the oxygen concentration is low, the hardness of the conductor used for the stranded wire is difficult to decrease, so the oxygen concentration is controlled to an amount exceeding 2 mass ppm. Further, when the oxygen concentration is high, the surface of the conductor is likely to be damaged in the hot rolling process, so it is controlled to 30 mass ppm or less.

(3) About dispersed substances It is preferable that the size of the dispersed particles dispersed in the conductor used in the CV cable, the transverse winding, etc. according to the present embodiment is small, and the dispersed particles are contained in the conductor. It is preferable that many are dispersed. The reason for this is that the dispersed particles have a function as a sulfur precipitation site, and the precipitation sites are required to have a small size and a large number. As a result, the formation of the dispersed particles and the deposition of sulfur on the dispersed particles are required. This is because the purity of the matrix of the copper base material is improved and the material hardness is reduced.

Specifically, sulfur and titanium contained in the conductor are TiO, TiO ₂ , TiS, or a compound having a Ti—O—S bond or a compound having a TiO, TiO ₂ , TiS, or Ti—O—S bond. It is contained as an aggregate and the remaining Ti and S are contained as a solid solution.

(4) About the property of the conductor before twisted wire processing Use a hard copper wire. The hard copper wire is preferably 50% or more in workability or 110 or more in Vickers hardness. The reason why the degree of work or the Vickers hardness is defined in this way is that if the value is less than this value, the softening of the conductor by the heat treatment after the stranded wire processing cannot be enjoyed effectively.

(5) About the twisted wire according to the present invention The twisted wire should have a Vickers hardness of 70 or less, preferably 60 or less. The reason specified in this way is that when the Vickers hardness exceeds this value, the soft characteristics of the cable are insufficient, and there is a possibility that inconvenience may occur at the time of cable routing.

  Next, the manufacturing method of the conductor used for the twisted wire which concerns on this Embodiment is demonstrated.

  The manufacturing method of the conductor used for the twisted wire which concerns on this Embodiment is as follows. As an example, a case where Ti is selected as an additive element will be described.

  First, a soft diluted copper alloy material containing Ti as a raw material for stranded wire is prepared (raw material preparation step).

  Next, this soft dilute copper alloy material is made into a molten metal at a molten copper temperature of 1100 ° C. or higher and 1320 ° C. or lower (melt manufacturing process).

  Next, a wire rod is produced from the molten metal (wire rod production process). Subsequently, the wire rod is hot-rolled at a temperature of 880 ° C. or lower and 550 ° C. or higher (hot rolling step).

  Further, the wire rod that has undergone the hot rolling process is subjected to wire drawing and heat treatment (wire drawing, heat treatment step).

  As a heat treatment method, traveling annealing using a tubular furnace, electric annealing using resistance heat generation, or the like can be applied. In addition, batch-type annealing is also possible. Thereby, the conductor used for the twisted wire which concerns on this Embodiment is manufactured.

  In addition, the conductor is manufactured using the soft dilute copper alloy material containing the above-described sulfur of 2 mass ppm to 12 mass ppm, oxygen of 2 mass ppm to 30 mass ppm, and titanium of 4 mass ppm to 55 mass ppm. Is preferred.

  Therefore, the present inventor has studied the following two measures in order to realize a decrease in the hardness of the conductor used in the stranded wire according to the present embodiment and an improvement in the conductivity of the conductor.

  And the conductor used for the twisted wire which concerns on this Embodiment was obtained by using together the following two measures for manufacture of a copper wire rod.

First, the first strategy is to prepare a molten Cu in a state where titanium (Ti) is added to Cu having an oxygen concentration exceeding 2 mass ppm. It is considered that TiS and titanium oxide (for example, TiO ₂ ) and Ti—O—S particles are formed in the molten metal.

Next, the second policy aims to facilitate the precipitation of sulfur (S) by introducing dislocations in the copper, and the temperature in the hot rolling process is set to the temperature in the normal copper production conditions (that is, , 950 ° C. to 600 ° C.) lower temperature (880 ° C. to 550 ° C.). With such a temperature setting, S can be precipitated on dislocations or by using titanium oxide (for example, TiO ₂ ) as a nucleus.

  By the first and second measures described above, sulfur contained in copper crystallizes and precipitates, so that a copper wire rod having desired soft characteristics and desired conductivity is obtained after cold drawing. be able to.

  The conductor used for the stranded wire according to the present embodiment uses SCR continuous casting equipment, has few scratches on the surface, has a wide manufacturing range, and can be stably produced.

  By SCR continuous casting and rolling, a wire rod is manufactured with an ingot rod working degree of 90% (30 mm) to 99.8% (5 mm). As an example, a condition for manufacturing a wire rod of φ8 mm with a processing degree of 99.3% is adopted.

  The molten copper temperature in the melting furnace is preferably controlled to 1100 ° C. or higher and 1320 ° C. or lower. When the temperature of the molten copper is high, blowholes increase, and scratches are generated and the particle size tends to increase, so the temperature is controlled to 1320 ° C. or lower. Moreover, although the reason for controlling to 1100 degreeC or more is because copper is hardened easily and manufacture is not stable, molten copper temperature is desirable as low as possible.

  As for the temperature of the hot rolling process, it is preferable to control the temperature in the first rolling roll to 880 ° C. or lower and the temperature in the final rolling roll to 550 ° C. or higher.

  These casting conditions are different from normal pure copper production conditions, and aim to further reduce the solid solubility limit, which is the driving force for sulfur crystallization in molten copper and precipitation of sulfur during hot rolling. Is.

  Further, the temperature in the normal hot rolling process is 950 ° C. or less in the first rolling roll and 600 ° C. or more in the final rolling roll, but for the purpose of reducing the solid solution limit, It is desirable to set 880 ° C. or lower for the first rolling roll and 550 ° C. or higher for the final rolling roll.

  The reason why the temperature in the final rolling roll is set to 550 ° C. or higher is that when the temperature is lower than 550 ° C., the obtained wire rod has many scratches and the manufactured conductor cannot be handled as a product. The temperature in the hot rolling process is preferably as low as possible while controlling the temperature to 880 ° C. or lower in the first rolling roll and 550 ° C. or higher in the final rolling roll. By setting such a temperature, the hardness of the conductor matrix can be made close to that of high-purity copper (5N or more).

  After the base material copper is melted in the shaft furnace, it is preferably flowed into the trough in a reduced state. That is, in a reducing gas (for example, CO) atmosphere, the wire rod is stably manufactured by casting while controlling the sulfur concentration, titanium concentration, and oxygen concentration of the dilute alloy and rolling the material. It is preferable. In addition, mixing of copper oxide and / or a particle size larger than a predetermined size degrades the quality of the manufactured conductor.

  From the above, a soft dilute copper alloy material that is softer than the conductor of tough pitch copper (TPC) can be obtained as a raw material for the conductor used in the stranded wire according to the present embodiment.

  A plating layer can also be formed on the surface of the soft dilute copper alloy material. Furthermore, the shape of the soft dilute copper alloy material is not particularly limited, and can be a round cross-section, a rod, or a flat conductor.

  In the present embodiment, the wire rod is manufactured by the SCR continuous casting and rolling method, and the soft material is manufactured by hot rolling, but the twin roll type continuous casting rolling method or the Properti type continuous casting and rolling method is adopted. You can also.

(Effect of embodiment)
The insulated wire according to this embodiment has high productivity, excellent softening temperature, little work hardening at the time of cable completion, and excellent soft flexibility. In addition, the insulated wire according to the present embodiment can reduce energy costs such as electric power consumed in the annealing process of the conductor, equipment costs in the annealing process, equipment maintenance costs, time required for the annealing process, labor costs, and the like.

  Below, the Example of the strand wire used as a conductor of the cable of this invention or an insulated wire is described.

Example 1;
First, a φ8 mm copper wire (wire rod, workability 99.3%) having an oxygen concentration of 7 mass ppm to 8 mass ppm, a sulfur concentration of 5 mass ppm, and a titanium concentration of 13 mass ppm was prepared.

  Next, the wire rod is drawn (working degree: 89.4%) to obtain a final wire diameter (for example, φ2.61 mm), and then, for example, a twisted wire having seven strands is prepared, Finish to size. Next, after putting into an annealing furnace and making a tempered copper stranded wire at a predetermined temperature and time, it is coated with a resin to form the insulator 3 (coating step).

  This annealing step is performed, for example, by heating at a low temperature in a batch type annealing furnace. At the time of annealing, heat at an annealing temperature (150 ° C. to 180 ° C.) is applied to the conductor 2.

Comparative Example 1
The sample of Comparative Example 1 was produced in the same manner as in the above example except that tough pitch copper was used as a raw material.

  Using the conductive material of Example 1 and the tough pitch copper of Comparative Example 1, a hard copper wire drawn from a conventional 8.0 mm diameter to a desired final diameter of 2.61 mm was annealed with a current-carrying annealer. The strands made of annealed copper wire are twisted together to produce a stranded wire, and the results of measuring the Vickers hardness after heat treatment under the respective heat treatment conditions are shown in FIG. It was.

  It can be seen from FIG. 2 that the Vickers hardness of the conductors of both the comparative material 1 and the implementation material 1 are not much different from those in the initial state even after heat treatment.

  Next, using the conductor material of Example 1 and the tough pitch copper of Comparative Example 1, based on the manufacturing method of the present invention, a hard copper wire drawn from φ8.0 mm to a desired final wire diameter φ2.61 mm is twisted. FIG. 3 shows the results of measuring the Vickers hardness after the combined stranded wires were heat-treated under the respective heat-treatment conditions to obtain the working material 2 and the comparative material 2.

  As shown in FIG. 3, the material obtained by annealing the stranded wire obtained by twisting the hard copper wires is not changed at 150 ° C. and 1 h in the comparative material 2, and finally the Vickers hardness is up to 86 HV by the heat treatment at 180 ° C. and 1 h. Although it does not decrease, it can be seen that the embodiment material 2 is a sufficiently soft stranded wire at 60 ° C. for 1 hour at 150 ° C. and 61 HV at 180 ° C. for 1 hour.

  Moreover, in the implementation material 2, in the comparatively low-temperature annealing conditions of 150 degreeC and 1 h, a remarkable difference arises in terms of a soft characteristic compared with the comparison material 2, and after twisting a hard copper wire It can be seen that there is a particularly significant difference when annealed.

  In the process of twisting the conventional annealed copper wire, the twisted wire may become hard due to processing strain when twisted, but as in the present invention, using a copper material added with a predetermined additive element, By twisting the hard copper wire and then annealing the stranded wire, it is possible to cover the insulator with the soft stranded wire.

  Next, a cable (insulated cable) 1 is produced by extrusion coating a sheath 5 (for example, a vinyl sheath, a polyethylene sheath, a flame resistant polyethylene sheath).

  The cable manufacturing method of the present embodiment is not limited to a stranded single-core insulated cable, but is an insulated cable produced by twisting a plurality of insulated wires and further extruding a sheath. May be.

Example 2;
First, the manufacturing process of the stranded wire is the same as that of the first embodiment.

  Next, while running this stranded wire, it annealed through the tubular furnace and produced the stranded wire, and it was set as the implementation material 4. FIG.

  The sample of the comparative example was manufactured in the same manner as the above-described embodiment material 4 except that tough pitch copper was used as a raw material.

  Moreover, the conductor material of Example 1 and the tough pitch copper of Comparative Example 1 were annealed with a current-carrying annealer by drawing a hard copper wire having a desired final wire diameter of φ2.61 mm from φ8.0 mm, which is conventionally practiced. FIG. 4 shows the results of measuring the Vickers hardness after heat-treating each of the heat treatment conditions after preparing a stranded wire by twisting together the strands made into an annealed copper wire to make the embodiment material 3 and the comparative material 3. Indicated.

  It can be seen from FIG. 4 that the Vickers hardness of the conductors of both the comparative material 3 and the implementation material 3 are not much different from those in the initial state even after the heat treatment.

  On the other hand, the execution material 4 and the comparative material 4 were heat-treated as described above after twisting a twisted copper wire drawn from φ8.0 mm to a desired final wire diameter φ2.61 mm. The result of having measured the Vickers hardness of is shown.

  As shown in FIG. 5, the material obtained by annealing the stranded wire obtained by twisting the hard copper wires is reduced only to 76 HV in the comparative material 4, but is reduced to 61 HV in the implementation material 4 and becomes a sufficiently soft conductor. I understand that.

  Also in Example 2 above, the same effect as in Example 1 above is recognized, using a copper material added with a predetermined additive element, twisting this hard copper wire, and then annealing the twisted wire, The conductor 2 can be effectively softened by the heat treatment in this annealing step.

  For this reason, even if work hardening occurs in the stranded wire process, it is possible to realize a stranded wire having softness compared to a stranded wire made of tough pitch copper.

  Next, a stranded wire is produced with the conductor 2, and the insulated wire 4 is produced by extrusion-coating the resin on the stranded wire. Next, the cable 1 is produced by extruding the sheath 5 on the insulated wire 4.

Example 3;
[Example of lightly compressed tin-plated stranded wire]
For example, a production example of 37 light compression tin plating stranded wires having a diameter of 0.26 mm will be described.

  Production up to φ8.0 mm is performed in the same manner as in Examples 1 and 2.

  A wire having a desired final wire diameter of 0.9 mm is manufactured by drawing from φ8.0 mm, hot tin plating is performed on this 0.9 mm diameter, and then 0.26 mm diameter is obtained by cold drawing. Until it is drawn. After twisting 37 obtained tin-plating strands with a twisting machine, the wire is subjected to mild compression to adjust the cross-sectional shape of the twisted wire to a circular cross-section. This is referred to as an implementation material 6.

  Usually, hot tin plating is performed with a diameter of 0.9 mm, and then the wire drawn to a diameter of 0.26 mm by cold drawing is passed through an energization annealer and annealed by resistance heating due to energization. A 26 mm diameter tinned annealed copper wire is obtained. Using this as a stranded wire, a material using the same raw material as in Example 1 is referred to as Example Material 5, and a material using tough pitch copper (TPC) as a raw material is referred to as Comparative Material 5.

  Comparative material 6 is manufactured in the same manner as Example 6 except that tough pitch copper (TPC) is used as a raw material, and 37 tin-plated soft copper wires having a diameter of 0.26 mm are twisted together and subjected to mild compression. I prepared what I did.

  FIG. 6 shows a Vickers hardness test of a cross-section after heat treatment at each temperature for 1 hour of the comparative material 5 and 37 of the comparative material 5 in which 37 soft tin-plated copper wires having a diameter of 0.26 mm were stranded. It is the graph which compared the result.

  The comparative material 5 is formed by twisting 37 0.26 mm-diameter tin-plated hard copper wires made of tough pitch copper (TPC).

  FIG. 7 shows Vickers hardness test results after heat treatment at each temperature of Comparative Material 6 and Example Material 6 in which 37 pieces of 0.26 mm diameter tin-plated hard copper wires were twisted and subjected to mild compression processing. It is the graph compared.

  From FIG. 5, in the conventional construction method, the Vickers hardness decreases only to 85 (HV) even when using the implementation material 5, but in the implementation material 6 in which the hard copper wire of FIG. After the heat treatment for 1 h, the Vickers hardness decreases to 70 (HV) and becomes soft.

  By annealing this material and the stranded wire, the Vickers hardness of the stranded wire, which has conventionally been reduced only to 85 (HV), can be reduced to 70 (HV). Furthermore, at 180 ° C. and 1 h, the temperature can be reduced to 66 (HV), that is, a soft stranded wire can be obtained.

  As mentioned above, according to said Examples 1-3, since it can be set as a cable with a soft stranded wire, even if it is work-hardened by processing distortion when producing a stranded wire, a soft insulated wire or cable can be used. Can be obtained. Compared to a conventional twisted wire made of tough pitch copper (TPC), which is a comparative material, even if a hard copper wire is twisted and annealed at the same temperature, a softer twisted wire can be obtained.

  As a result, the cost of electricity can be reduced. That is, there is no need for a large annealing apparatus for the annealing process. Therefore, it is possible to heat the conductor 2 with low-cost equipment, and it is possible to produce the cable 1 that is less affected by work hardening.

  As mentioned above, although embodiment of this invention and its Example were demonstrated, embodiment and Example described above do not limit the invention which concerns on a claim. It should be noted that not all combinations of features described in the embodiments and examples are necessarily essential to the means for solving the problems of the invention.

1 Cable 2 Conductor 3 Insulator 4 Insulated Wire 5 Sheath

Claims (5)

A dilute copper alloy wire containing copper containing inevitable impurities, oxygen in an amount exceeding 2 mass ppm, and at least one additive element of Mg, Zr, Nb, Ca, V, N, Mn, Ti, Cr, A hard copper wire production process for producing a hard copper wire by drawing a wire with a workability of 50% or more so as to obtain a final wire diameter;
Preparing a plurality of the hard copper wires and twisting them together to produce a stranded wire; and
A preheating step of pre-heat-treating the stranded wire to transform the hard copper wire into an annealed copper wire;
A method for producing a stranded wire, comprising:   2. The method for producing a stranded wire according to claim 1, wherein the additive element is titanium of 4 mass ppm or more and 55 mass ppm or less, and includes sulfur of 2 mass ppm or more and 12 mass ppm or less and oxygen of more than 2 mass ppm and 30 mass ppm or less. . A dilute copper alloy wire containing copper containing inevitable impurities, oxygen in an amount exceeding 2 mass ppm, and at least one additive element of Mg, Zr, Nb, Ca, V, N, Mn, Ti, Cr, A hard copper wire production process for producing a hard copper wire by drawing a wire with a workability of 50% or more so as to obtain a final wire diameter;
Preparing a plurality of the hard copper wires and twisting them together to produce a stranded wire; and
A preheating step of pre-heat-treating the stranded wire to transform the hard copper wire into an annealed copper wire;
A coating step of coating the outer periphery of the stranded wire with a resin;
A method for producing an insulated wire, comprising:   4. The method for producing an insulated wire according to claim 3, wherein the additive element is titanium of 4 mass ppm to 55 mass ppm, and includes sulfur of 2 mass ppm to 12 mass ppm and oxygen of more than 2 mass ppm and not more than 30 mass ppm. .   A stranded wire obtained by the method for producing a stranded wire according to claim 1 or 2.