WO2023228468A1 - Twisted wire, insulated wire, and cable - Google Patents

Abstract

This twisted wire is obtained by twisting a plurality of sub-twisted wires together. Each of the sub-twisted wires has the same structure in which a plurality of strands of which the cross-sectional shapes perpendicular to the longitudinal direction are circles of the same diameter, are twisted together. The strands include a steel core wire, and a copper or copper alloy cover layer covering the surface of the core wire. The twist pitch of the sub-twisted wires is at least 40 times the diameter of the circumscribed circle of the sub-twisted wires. The twist pitch of the twisted wires is 5-20 times the diameter of the circumscribed circle of the twisted wires.

Description

Stranded wire, insulated wire and cable

The present disclosure relates to stranded wires, insulated wires, and cables.

This application claims priority based on Japanese Application No. 2022-85853 filed on May 26, 2022, and incorporates all the contents described in the said Japanese application.

Stranded wires, insulated wires, and cables used in moving parts that bend during operation in FA (Factory Automation) equipment, robots, automobiles, other industrial equipment, consumer equipment, etc. have only tensile strength and other strengths. Rather, durability against repeated bending stress, that is, bending resistance is required. On the other hand, it has been proposed to use a clad wire that includes a steel core wire and a copper coating layer that covers the drawn wire as the wire (for example, Japanese Patent Application Laid-Open No. 2020-21620 (Patent Document 1) reference). The steel core wire contributes to improved strength, and the copper coating layer provides high conductivity.

JP2020-21620A

A stranded wire according to the present disclosure is a stranded wire in which a plurality of child strands are twisted together. Each of the child stranded wires has the same structure in which a plurality of wires each having a circular cross-sectional shape perpendicular to the longitudinal direction and having the same diameter are twisted together. The strand includes a steel core wire and a copper or copper alloy coating layer that covers the surface of the core wire. The twisting pitch of the child strands is 40 times or more the diameter of the circumscribed circle of the child strands. The twisting pitch of the stranded wire is 5 times or more and 20 times or less the diameter of the circumscribed circle of the stranded wire.

FIG. 1 is a schematic diagram showing the structure of a twisted wire. FIG. 2 is a schematic diagram showing the structure of a child strand. FIG. 3 is a schematic cross-sectional view showing the structure of the wire. FIG. 4 is a schematic cross-sectional view showing the structure of the twisted wire. FIG. 5 is a schematic diagram for explaining the twist pitch of the twisted wire and the child twisted wire. FIG. 6 is a flowchart outlining a method for manufacturing stranded wire. FIG. 7 is a schematic diagram showing the structure of twisted wires in the second embodiment. FIG. 8 is a schematic diagram showing the structure of an insulated wire in Embodiment 3. FIG. 9 is a schematic diagram showing the structure of a cable in Embodiment 4. FIG. 10 is a schematic diagram showing the structure of a cable in Embodiment 5. FIG. 11 is a schematic perspective view showing a connection state between an insulated wire and a crimp terminal. FIG. 12 is a schematic diagram for explaining the tensile test method. FIG. 13 is a schematic perspective view showing the structure of a test device for a bending test. FIG. 14 is a schematic diagram for explaining the bending test method. FIG. 15 is a schematic diagram for explaining the bending test method.

[Problems that this disclosure seeks to solve]
In the above stranded wires, insulated wires, and cables, connection with crimp terminals is important as a simple connection method. However, when the above-mentioned clad wire is used as a wire, since the toughness of the steel core wire is low, the core wire may crack when connected to a crimp terminal. Due to this cracking of the core wire, a problem may arise in that the crimp strength decreases.

Therefore, it is an object of the present invention to provide stranded wires, insulated wires, and cables that not only improve bending resistance but also achieve both strength and conductivity, and can suppress cracking of core wires when connected to crimp terminals. is one of the objectives of this disclosure.

[Effects of this disclosure]
According to the above-mentioned stranded wire, it is possible not only to improve bending resistance but also to achieve both strength and conductivity, and to suppress cracking of the core wire during connection with a crimp terminal.

[Description of embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described. The stranded wire of the present disclosure is a stranded wire in which a plurality of child strands are twisted together. Each of the child stranded wires has the same structure in which a plurality of wires each having a circular cross-sectional shape perpendicular to the longitudinal direction and having the same diameter are twisted together. The strand includes a steel core wire and a copper or copper alloy coating layer that covers the surface of the core wire. The twisting pitch of the child strands is 40 times or more the diameter of the circumscribed circle of the child strands. The twisting pitch of the stranded wire is 5 times or more and 20 times or less the diameter of the circumscribed circle of the stranded wire.

The stranded wire of the present disclosure is configured by further twisting a plurality of child stranded wires, which are formed by twisting element wires together. This provides high flexibility and ensures a certain degree of bending resistance. The strands constituting the child stranded wire include a steel core wire and a coating layer made of copper or copper alloy that covers the surface of the core wire. This makes it possible to achieve both strength and conductivity. Since the shape of the cross section perpendicular to the longitudinal direction of each strand is circular with the same diameter, local stress concentration during repeated bending is reduced, contributing to improvement in bending resistance. Furthermore, by setting the twisting pitch of the child stranded wire to 40 times or more the diameter of the circumscribed circle of the child stranded wire, the wires are properly rearranged when connecting with the crimp terminal, and some of the wires are stress concentration is avoided. As a result, cracking of the core wire during connection with the crimp terminal is suppressed. Furthermore, by making the twisting pitch of the stranded wire five times or more the diameter of the circumscribed circle of the stranded wire, unevenness on the surface of the stranded wire can be suppressed and bending resistance can be improved. Furthermore, by setting the twisting pitch of the stranded wires to be 20 times or less the diameter of the circumscribed circle of the stranded wires, it is possible to avoid concentration of stress on some child strands during bending. In addition, in this application, the state in which the strands constituting a child strand have the same diameter means that the average diameter and the diameter of each strand are the same, with respect to the average diameter of a plurality of strands constituting each child strand A state in which the difference between the two is 6.0% or less.

As described above, according to the stranded wire of the present disclosure, it is possible to not only improve bending resistance but also achieve both strength and conductivity, as well as suppress cracking of the core wire when connecting with a crimp terminal. .

In the above stranded wire, the diameter of the strands may be 0.02 mm or more and 0.09 mm or less. By setting the diameter of the strands to 0.02 mm or more, it is possible to suppress breakage of the strands in the stranded wire manufacturing process and improve productivity. By setting the diameter of the strand to 0.09 mm or less, the difference in strain between the outside and the inside of the bend when the strand is bent is suppressed, and the bending resistance is further improved.

In the above stranded wire, the tensile strength of the core wire may be 1800 MPa or more and 4500 MPa or less. When the tensile strength of the core wire is 1800 MPa or more, it becomes easy to impart sufficient strength to the core wire. When the tensile strength of the core wire is 4500 MPa or less, it becomes easy to impart sufficient toughness to the core wire.

In the above stranded wire, the carbon content of the steel constituting the core wire may be 0.70% by mass or more and 0.95% by mass or less. The carbon content of steel has a significant impact on the strength and toughness of the steel. By setting the carbon content of the steel constituting the core wire to 0.70% by mass or more, it becomes easy to impart sufficient strength to the core wire. By setting the carbon content of the steel constituting the core wire to 0.95% by mass or less, it becomes easy to impart sufficient toughness to the core wire.

In the above-mentioned stranded wire, in a cross section perpendicular to the longitudinal direction of the strands, the area of the coating layer relative to the area of the strands may be 20% or more and 80% or less. By setting the area of the coating layer to the area of the wire to be 20% or more, it becomes easy to obtain sufficient conductivity. By controlling the area of the coating layer to 80% or less of the area of the wire, it becomes easy to obtain sufficient strength and bending resistance.

The stranded wire in one aspect of the present disclosure is a stranded wire in which a plurality of child stranded wires are twisted together. Each of the child stranded wires has the same structure in which a plurality of wires each having a circular cross-sectional shape perpendicular to the longitudinal direction and having the same diameter are twisted together. The strand includes a steel core wire and a copper or copper alloy coating layer that covers the surface of the core wire. The twisting pitch of the child strands is 40 times or more the diameter of the circumscribed circle of the child strands. The twisting pitch of the stranded wire is 5 times or more and 20 times or less the diameter of the circumscribed circle of the stranded wire. The diameter of the core wire is 0.02 mm or more and 0.09 mm or less. The tensile strength of the core wire is 1800 MPa or more and 4500 MPa or less. The carbon content of the steel constituting the core wire is 0.70% by mass or more and 0.95% by mass or less. In a cross section perpendicular to the longitudinal direction of the wire, the area of the coating layer relative to the area of the wire is 20% or more and 80% or less. In a cross section perpendicular to the longitudinal direction of the stranded wires, the plurality of child stranded wires are arranged in contact with the central child stranded wire so as to surround the central child stranded wire and the outer peripheral side of the central child stranded wire. and six first peripheral child strands. The child strands include 2 or more and 20 or less strands.

A stranded wire in another aspect of the present disclosure is a stranded wire in which a plurality of child strands are twisted together. Each of the child stranded wires has the same structure in which a plurality of wires each having a circular cross-sectional shape perpendicular to the longitudinal direction and having the same diameter are twisted together. The strand includes a steel core wire and a copper or copper alloy coating layer that covers the surface of the core wire. The twisting pitch of the child strands is 40 times or more the diameter of the circumscribed circle of the child strands. The twisting pitch of the stranded wire is 5 times or more and 20 times or less the diameter of the circumscribed circle of the stranded wire. The diameter of the core wire is 0.02 mm or more and 0.09 mm or less. The tensile strength of the core wire is 1800 MPa or more and 4500 MPa or less. The carbon content of the steel constituting the core wire is 0.70% by mass or more and 0.95% by mass or less. In a cross section perpendicular to the longitudinal direction of the wire, the area of the coating layer relative to the area of the wire is 20% or more and 80% or less. In a cross section perpendicular to the longitudinal direction of the stranded wires, the plurality of child stranded wires are arranged in contact with the central child stranded wire so as to surround the central child stranded wire and the outer peripheral side of the central child stranded wire. 6 first circumferential twisted wires arranged in contact with the first circumferential twisted wires and 12 second circumferential twisted wires arranged in contact with the first circumferential twisted wires on the outer peripheral side of the area where the first circumferential twisted wires are arranged. and, including. The child strands include 2 or more and 20 or less strands.

The child strands have a structure including a center child strand and a first peripheral child strand as described above, or a structure including a center child strand, a first peripheral child strand, and a second peripheral child strand. As a result, the cross section perpendicular to the longitudinal direction of the stranded wire becomes nearly circular. As a result, local stress concentration during repeated bending is reduced and bending resistance is improved. Furthermore, since the child stranded wire includes two or more strands, the flexibility of the stranded wire can be ensured and the bending resistance can be improved. When the child stranded wire includes 20 or less strands, a practical outer diameter of the stranded wire can be obtained when used as an electric wire.

In the above stranded wire, the coating layer may be a plating layer. That is, the covering layer may be formed by plating. The plating layer is suitable as the coating layer of the present disclosure because its thickness can be easily adjusted and it can be formed by a simple process.

An insulated wire according to one embodiment of the present disclosure includes the stranded wire of the present disclosure described above and an insulating layer that covers the outer periphery of the stranded wire. According to an insulated wire according to one aspect of the present disclosure, the insulated wire not only has improved bending resistance, but also achieves both strength and conductivity, and can suppress cracking of the core wire when connected to a crimp terminal. Provides an insulated wire that not only improves bending resistance but also achieves both strength and conductivity by including the disclosed stranded wire, and can suppress cracking of the core wire when connected to a crimp terminal. can do.

An insulated wire according to another aspect of the present disclosure includes a core in which a plurality of insulated strands are twisted together, and a protective layer made of an insulator that covers the outer periphery of the core. Each of the insulated strands includes the strands of the present disclosure described above and an insulating layer covering the outer periphery of the strands. According to the insulated wire according to another aspect of the present disclosure, it is possible not only to improve bending resistance but also to achieve both strength and conductivity, and to suppress cracking of the core wire when connecting with a crimp terminal. By including the stranded wire of the present disclosure, an insulated wire that not only improves bending resistance but also achieves both strength and conductivity, and can suppress cracking of the core wire when connected to a crimp terminal. can be provided.

A cable according to one aspect of the present disclosure includes the insulated wire according to the above-described one aspect of the present disclosure, a shield portion made of a conductor that is arranged to surround the outer periphery of the insulated wire, and a cable that is arranged so as to surround the outer periphery of the shield portion. an outer skin layer made of an insulator. According to the cable according to one aspect of the present disclosure, the present disclosure can not only improve bending resistance but also achieve both strength and conductivity, and suppress cracking of the core wire when connecting with a crimp terminal. To provide a cable that not only improves bending resistance but also achieves both strength and conductivity by including stranded wires, and can suppress cracking of the core wire when connecting with a crimp terminal. I can do it.

A cable according to another aspect of the present disclosure includes the insulated wire according to the other aspect of the present disclosure, a shield portion made of a conductor arranged so as to surround the outer periphery of the insulated wire, and a shield portion arranged so as to surround the outer periphery of the shield portion. and an outer skin layer made of an insulator. According to a cable according to another aspect of the present disclosure, the cable has not only improved bending resistance but also achieves both strength and conductivity, and can suppress cracking of the core wire when connecting with a crimp terminal. To provide a cable that not only improves bending resistance but also achieves both strength and conductivity by including the disclosed stranded wire, and can suppress cracking of the core wire when connecting with a crimp terminal. be able to.

[Details of embodiments of the present disclosure]
Next, embodiments of stranded wires, insulated wires, and cables according to the present disclosure will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are given the same reference numerals and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic diagram showing the structure of a twisted wire. Referring to FIG. 1, stranded wire 1 in this embodiment has a structure in which a plurality of child stranded wires 10 are twisted together. In this embodiment, the plurality of child strands 10 include one central child strand 10A and six first peripheral child strands 10B. In a cross section perpendicular to the longitudinal direction of the stranded wire 1, the central child strand 10A is located at the center. The six first peripheral child strands 10B are arranged in contact with the center child strand 10A so as to surround the outer peripheral side of the center child strand 10A. The central child strand 10A is in contact with all six first peripheral child strands 10B on its outer peripheral surface. Each first peripheral child strand 10B is in contact with two circumferentially adjacent first peripheral child strands 10B and the center child strand 10A on the outer peripheral surface.

FIG. 2 is a schematic diagram showing the structure of the child strands. Referring to FIG. 2, each of the child strands 10 has the same structure in which a plurality of wires 100 whose cross-sectional shape perpendicular to the longitudinal direction is circular and have the same diameter are twisted together. In this embodiment, the plurality of wires 100 include one central wire 100A and six first peripheral wires 100B. The child twisted wire 10 includes 2 or more and 20 or less (specifically 7) strands 100. In a cross section perpendicular to the longitudinal direction of the stranded wire 1, the central strand 100A is arranged at the center. The six first peripheral wires 100B are arranged in contact with the center wire 100A so as to surround the outer peripheral side of the center wire 100A. The central strand 100A is in contact with all six first peripheral strands 100B on its outer peripheral surface. Each first peripheral strand 100B is in contact with two first peripheral strands 100B adjacent to each other in the circumferential direction and the center strand 100A on the outer peripheral surface.

FIG. 3 is a schematic cross-sectional view showing the structure of the wire. FIG. 3 shows a cross section perpendicular to the longitudinal direction of the strand. Referring to FIG. 3, strand 100 includes a core wire 101 and a covering layer 102. Core wire 101 is made of steel. The diameter of the wire 100 is, for example, 0.02 mm or more and 0.09 mm or less. The carbon content of the steel that constitutes the core wire 101 can be, for example, 0.70% by mass or more and 0.95% by mass or less. The carbon content of the steel that constitutes the core wire 101 may be 0.90% by mass or less. As the steel constituting the core wire 101, for example, steel corresponding to piano wire specified in JIS (Japanese Industrial Standards) G3502 can be adopted. The tensile strength of the core wire 101 may be, for example, 1800 MPa or more and 4500 MPa or less. The tensile strength of the core wire 101 can be 2500 MPa or more. The tensile strength of the core wire 101 can be 3800 MPa or less.

The covering layer 102 is made of copper (Cu) or a copper alloy. The covering layer 102 covers the surface 101A (outer peripheral surface) of the core wire 101. The thickness of the covering layer 102 is constant in the circumferential direction. The coating layer 102 may be a plating layer. The covering layer 102 may be a layer formed by plating. In a cross section perpendicular to the longitudinal direction of the wire 100 (the cross section shown in FIG. 3), the area of the coating layer 102 relative to the area of the wire 100 may be 20% or more and 80% or less. Note that the state where the thickness of the coating layer 102 is constant in the circumferential direction means that the difference between the maximum value and the minimum value of the thickness is 7.0 with respect to the average value of the thickness of the coating layer 102 in each strand 100. % or less.

FIG. 4 is a schematic cross-sectional view showing the structure of the twisted wire. FIG. 5 is a schematic diagram for explaining the twist pitch of the twisted wire and the child twisted wire. FIG. 4 shows a cross section perpendicular to the longitudinal direction of the strand 1. Referring to FIGS. 4 and 5, in this embodiment, the twist pitch P of the child strands 10 is 40 times or more the diameter _d2 of the circumscribed circle of the child strands 10. Here, with reference to the reference numbers in parentheses in FIG. The length is defined as the length measured parallel to the longitudinal direction of the child strands 10. Further, in this embodiment, the twist pitch P of the stranded wire 1 is 5 times or more and 20 times or less the diameter _d1 of the circumscribed circle of the stranded wire 1. Here, with reference to the reference numbers (excluding those written in parentheses) in FIG. is defined as the length measured parallel to the longitudinal direction of the strand 1.

The stranded wire 1 of this embodiment is configured by further twisting a plurality of child strands 10, which are formed by twisting the strands 100 together. This provides high flexibility and ensures a certain degree of bending resistance. The strands 100 constituting the child stranded wire 10 include a core wire 101 made of steel and a coating layer 102 made of copper or copper alloy that covers the surface 101A of the core wire 101. This makes it possible to achieve both strength and conductivity. Since the shape of the cross section perpendicular to the longitudinal direction of each strand 100 is circular with the same diameter, local stress concentration during repeated bending is reduced, contributing to improvement in bending resistance. Furthermore, by setting the twist pitch P of the child stranded wire 10 to 40 times or more the diameter _d2 of the circumscribed circle of the child stranded wire 10, the strands 100 are appropriately rearranged when connecting with a crimp terminal, Concentration of stress on some of the wires 100 is avoided. As a result, cracking of the core wire 101 during connection with a crimp terminal is suppressed. Furthermore, by making the twist pitch P of the stranded wire 1 five times or more the diameter _d1 of the circumscribed circle of the stranded wire 1, it is possible to suppress unevenness on the surface of the stranded wire 1 and improve the bending resistance. It has become. Furthermore, by setting the twist pitch P of the stranded wire 1 to 20 times or less the diameter _d1 of the circumscribed circle of the stranded wire 1, it is possible to avoid concentration of stress on some of the child strands 10 during bending. . In this way, the stranded wire 1 of this embodiment not only improves bending resistance, but also achieves both strength and conductivity, and can suppress cracking of the core wire when connecting with a crimp terminal. It is a twisted wire.

Further, in the present embodiment, each of the plurality of child strands 10 constituting the stranded wire 1 has a central child strand 10A disposed at the center and a central child strand 10A arranged at the center in a cross section perpendicular to the longitudinal direction of the strand 1. It includes six first peripheral child strands 10B arranged in contact with the central child strand 10A so as to surround the outer circumferential side of the strand 10A. The child twisted wire 10 includes 2 or more and 20 or less strands 100. As a result, the cross section perpendicular to the longitudinal direction of the stranded wire 1 becomes nearly circular. As a result, local stress concentration during repeated bending is reduced and bending resistance is improved. Furthermore, since the child stranded wire 10 includes two or more strands 100, it is possible to ensure the flexibility of the stranded wire 1 and improve its bending resistance. Since the child stranded wire 10 includes 20 or less strands 100, it is possible to obtain a practical outer diameter of the stranded wire 1 when used as an electric wire.

Next, a method for manufacturing the stranded wire 1 in this embodiment will be described. FIG. 6 is a flowchart outlining a method for manufacturing stranded wire. Referring to FIG. 6, in the method for manufacturing stranded wire 1 according to the present embodiment, a raw material steel wire preparation step is first performed as step S10. In this step S10, a raw material steel wire is prepared. Specifically, a steel wire made of steel having a carbon content of 0.70% by mass or more and 0.95% by mass or less is prepared. The steel constituting the raw steel wire contains silicon (Si) of 0.4% by mass to 2.5% by mass, manganese (Mn) of 0.6% to 0.9% by mass, and 0.1% by mass. It may contain chromium (Cr) in an amount of 1.8% by mass or less. As the steel constituting the raw material steel wire, a piano wire rod (for example, SWRS82A) specified in G3502 can be adopted.

Next, a patenting step is performed as step S20. In this step S20, patenting is performed on the raw material steel wire prepared in step S10. Specifically, after the raw steel wire is heated to a temperature range equal to or higher than the austenitization temperature (A1 point), it is rapidly cooled to a temperature range higher than the martensitization start temperature (MS point), and then maintained in the temperature range. A heat treatment is performed. As a result, the metal structure of the raw material steel wire becomes a fine pearlite structure with a small lamella interval. Here, in the above patenting treatment, the treatment of heating the raw steel wire to a temperature range of A1 point or higher is preferably carried out in an inert gas atmosphere from the viewpoint of suppressing the occurrence of decarburization.

Next, a surface roughening step is performed as step S30. In this step S30, a surface roughening treatment is performed on the raw steel wire that has been patented in step S20. Specifically, the surface roughness of the raw steel wire is increased by bringing the surface of the raw steel wire into contact with an acid such as hydrochloric acid or sulfuric acid. The concentration of hydrochloric acid can be, for example, 35% by mass, and the concentration of sulfuric acid can be, for example, 65% by mass.

Next, a coating layer forming step is performed as step S40. In this step S40, a coating layer is formed on the first intermediate steel wire obtained by performing steps up to step S30. Specifically, for example, a coating layer made of copper (pure copper) is formed on the first intermediate steel wire by plating. Further, in addition to copper, a metal layer such as tin (Sn) or zinc (Zn) may be formed by plating, and by alloying these, a coating layer made of a copper alloy may be formed.

Next, a wire drawing step is performed as step S50. In this step S50, wire drawing (drawing) is performed on the second intermediate steel wire obtained by performing steps up to step S40. The true strain in the wire drawing process in step S50 can be, for example, 2.3 or more and 4.9 or less, and preferably 3.0 or more and 4.0 or less. Thereby, the strand 100 in this embodiment is obtained.

Next, a first stranding step is performed as step S60. In this step S60, the child stranded wire 10 is produced by twisting together the strands 100 obtained by performing steps up to step S50. Specifically, referring to FIG. 2, seven strands 100 produced in steps S10 to S50 are prepared, and one strand is twisted as a center strand 100A and six strands are twisted as a first peripheral strand 100B. match. As a result, a child twisted wire 10 is obtained. At this time, referring to FIGS. 4 and 5, the twist pitch P of the child stranded wire 10 is set to be 40 times or more the diameter _d2 of the circumscribed circle of the child stranded wire 10.

Next, a second stranding step is performed as step S70. In this step S70, the child strands 10 obtained in step S60 are twisted together to produce the strand 1. Specifically, with reference to FIG. 1, seven child strands 10 produced in step S60 are prepared, one as the central child strand 10A, and six as the first peripheral child strand 10B. Twist together. As a result, a twisted wire 1 is obtained. At this time, referring to FIGS. 4 and 5, the twist pitch P of the stranded wire 1 is set to be at least 5 times and at most 20 times the diameter _d1 of the circumscribed circle of the stranded wire 1. Through the above procedure, the stranded wire 1 of this embodiment can be easily manufactured.

(Embodiment 2)
Next, Embodiment 2, which is another embodiment of the present disclosure, will be described. FIG. 7 is a schematic diagram showing the structure of twisted wires in the second embodiment. Referring to FIG. 7 and FIG. 1, stranded wire 1 in Embodiment 2 basically has the same structure as stranded wire 1 in Embodiment 1, and produces similar effects. However, the stranded wire 1 of the second embodiment differs from that of the first embodiment in the number of child stranded wires 10 that constitute the stranded wire 1.

Referring to FIG. 7, the plurality of child strands 10 constituting the strand 1 of the present embodiment include a central child strand 10A arranged at the center in a cross section perpendicular to the longitudinal direction of the strand 1; Six first peripheral child strands 10B arranged in contact with the center child strand 10A so as to surround the outer peripheral side of the center child strand 10A, and the outer periphery of the area where the first peripheral child strands 10B are arranged. Twelve second circumferential strands 10C are disposed on the side in contact with the first circumferential strands 10B. In this embodiment, the twisted wire 1 includes 19 child twisted wires 10.

The central child strand 10A is in contact with all six first peripheral child strands 10B on the outer peripheral surface. Each first peripheral child strand 10B is in contact with two circumferentially adjacent first peripheral child strands 10B and the center child strand 10A on the outer peripheral surface. Each of the second circumferential strands 10C is in contact with two circumferentially adjacent second circumferential strands 10C and a first circumferential strand 10B located on the inside in the radial direction on its outer peripheral surface. The stranded wire 1 of this embodiment in which the number and arrangement of child stranded wires 10 included in the stranded wire 1 are changed in this way also has improved bending resistance, similar to the stranded wire 1 of the first embodiment. Rather, it is a stranded wire that achieves both strength and conductivity and can suppress cracking of the core wire when connected to a crimp terminal.

(Embodiment 3)
Next, as a third embodiment of the present disclosure, an example of an insulated wire of the present disclosure will be described. FIG. 8 is a schematic diagram showing the structure of an insulated wire in Embodiment 3. Referring to FIG. 8, insulated wire 3 of this embodiment includes a core 9 and an insulating layer 12. The core 9 has a structure in which a plurality of (here, two) insulated strands 2 are twisted together. The insulating layer 12 is made of an insulator such as resin. The insulating layer 12 is a protective layer disposed to cover the outer periphery of the core 9. The insulated stranded wire 2 includes the stranded wire 1 of the first embodiment or the second embodiment described above, and an insulating layer 11 that covers the outer periphery of the stranded wire 1. The insulating layer 11 is made of an insulator such as resin.

The insulated wire 3 of this embodiment not only has improved bending resistance, but also achieves both strength and conductivity, and can suppress cracking of the core wire when connected to a crimp terminal. By including the stranded wire 1 of form 1 or 2, it is possible not only to improve bending resistance but also to achieve both strength and conductivity, and to suppress cracking of the core wire 101 when connecting with a crimp terminal. It is an insulated wire. Further, the insulated stranded wire 2 constituting the core 9 can also be used as an insulated wire. That is, an insulated stranded wire 2 as an insulated wire in another embodiment includes the stranded wire 1 of the first or second embodiment described above, and an insulating layer 11 that covers the outer periphery of the stranded wire 1. The insulated stranded wire 2 not only has improved bending resistance, but also achieves both strength and conductivity, and can suppress cracking of the core wire 101 when connected to a crimp terminal. By including the strands 1 of 2, the insulated wire not only improves bending resistance but also achieves both strength and conductivity, and can suppress cracking of the core wire 101 when connected to a crimp terminal. It becomes.

(Embodiment 4)
Next, as Embodiment 4 of the present disclosure, an example of the cable of the present disclosure will be described. FIG. 9 is a schematic diagram showing the structure of a cable in Embodiment 4. Referring to FIG. 9, cable 300 includes stranded wire 1 of Embodiment 1 or Embodiment 2, insulating layer 4 disposed so as to cover outer periphery 1A of stranded wire 1, and outer peripheral surface of insulating layer 4. 4A, and an outer skin layer 6 that is arranged to cover the outer periphery 5A of the shield part 5. To explain from another point of view, the cable 300 includes the insulated stranded wire 2 as the insulated wire described in the third embodiment, and the shield portion 5 made of a conductor arranged so as to surround the outer periphery of the insulated stranded wire 2. , and an outer skin layer 6 made of an insulator disposed so as to surround the outer periphery of the shield portion 5. The shield portion 5 may have a structure in which metal wires are woven. As the metal wire constituting the shield portion 5, the strand 100 in the above embodiment may be employed.

The cable 300 of this embodiment not only has improved bending resistance, but also achieves both strength and conductivity, and can suppress cracking of the core wire 101 when connecting with a crimp terminal. By including the stranded wire 1 of form 1 or 2, it is possible not only to improve bending resistance but also to achieve both strength and conductivity, and to suppress cracking of the core wire 101 when connecting with a crimp terminal. It is a cable.

(Embodiment 5)
Next, as Embodiment 5 of the present disclosure, another example of the cable of the present disclosure will be described. FIG. 10 is a schematic diagram showing the structure of a cable in Embodiment 5. Referring to FIG. 10, a cable 400 according to the present embodiment includes the insulated wire 3 (see FIG. 8) described in the third embodiment, and a conductor made of a conductor arranged so as to surround the outer periphery of the insulated wire 3. It includes a shield part 5 and an outer skin layer 6 made of an insulator and arranged so as to surround the outer periphery 5A of the shield part 5. The shield portion 5 may have a structure in which metal wires are woven. As the metal wire constituting the shield portion 5, the strand 100 in the above embodiment may be employed.

The cable 400 of this embodiment not only has improved bending resistance, but also achieves both strength and conductivity, and can suppress cracking of the core wire 101 when connected to a crimp terminal. By including the stranded wire 1 of form 1 or 2, it is possible not only to improve bending resistance but also to achieve both strength and conductivity, and to suppress cracking of the core wire 101 when connecting with a crimp terminal. It is a cable.

An experiment was conducted to confirm the bending resistance of the stranded wire, insulated wire, and cable of the present disclosure, and the suppression of cracking of the core wire when connected to a crimp terminal. The experimental procedure is as follows.

Twisted wire 1 was prepared according to the manufacturing method described in Embodiment 1 above. The outer peripheral surface of this stranded wire 1 was covered with an insulating layer 11 to produce an insulated wire (insulated stranded wire 2). SWRS82A, which is a piano wire specified in JIS G3502, was used as the raw material steel wire prepared in step S10. In step S40, a pure copper coating layer 102 was formed by plating. By adjusting the thickness of the coating layer 102, the area ratio of the coating layer 102 in a cross section perpendicular to the longitudinal direction of the wire 100 was changed. In step S50, wire drawing was performed so that the outer diameter (diameter) of the wire 100 was 0.05 mm. Furthermore, in step S60, the twisting pitch of the child stranded wire 10 was changed to 60, and the number of strands 100 included in the child stranded wire 10 was varied in the range of 7 to 16. Further, in step S70, the twist pitch of the twisted wire 1 was changed. In this way, samples A to S were obtained. Further, in step S10, raw steel wires having different outer diameters and carbon contents were prepared, and by wire drawing in step S50, the outer diameter of the strands 100 was changed, thereby producing samples T to W.

Then, for the obtained sample, (1) the strength of the crimp part when connected to the crimp terminal and (2) the bending resistance were measured as follows.

(1) Strength of connection part when connected to crimp terminal FIG. 11 is a schematic perspective view showing a connection state between an insulated wire and a crimp terminal. FIG. 12 is a schematic diagram for explaining the tensile test method. Referring to FIG. 11, the crimp terminal 80 includes a main body 83, a conductor barrel 81 connected to the main body 83, and an insulator connected to the opposite side of the conductor barrel 81 from the side connected to the main body 83. ration barrel 82. When connecting the insulated stranded wire 2, which is an insulated wire, to the crimp terminal 80, the insulating layer 11 at the end of the insulated stranded wire 2 is first removed to expose the stranded wire 1. Then, by crimping the conductor barrel 81, the exposed strands 1 are held by the conductor barrel 81, and the insulating layer 11 is held by the insulation barrel 82. At this time, if cracks occur in the core wire 101 of the strands 100 constituting the stranded wire 1 held by the conductor barrel 81, the strength of the connection between the conductor barrel 81 and the stranded wire 1 decreases.

In this experiment, for each sample, while the stranded wire 1 was held by the conductor barrel 81 as described above, the insulated stranded wire 2 and the crimp terminal 80 were held in a state where the insulation layer 11 was not held by the insulation barrel 82. Connected. Then, as shown in FIG. 12, a tensile test is performed with the main body 83 of the crimp terminal 80 held by the first chuck 91 of the tensile tester, and the insulated stranded wire 2 held by the second chuck 92 of the tensile tester. The strength of the connection was evaluated based on the load at break.

(2) Flexibility Fig. 13 is a schematic perspective view showing the structure of a test device for a bending test. 14 and 15 are schematic diagrams for explaining the bending test method. Referring to FIG. 13, bending test device 70 includes mandrels 71 and 72, a pair of jigs 73a and 73b, and a weight 74. A weight 74 is attached to one end of the insulated stranded wire 2 in the longitudinal direction. In this test, the mass of the weight 74 was 100 g. A pair of jigs 73a and 73b sandwich the insulated strands 2. Mandrels 71 and 72 each having a cylindrical shape are arranged between the weight 74 and the jigs 73a and 73b. The outer circumferential surface 711 of the mandrel 71 and the outer circumferential surface 721 of the mandrel 72 contact the outer circumferential surface of the insulated stranded wire 2 . The longitudinal direction of the mandrels 71 and 72 is perpendicular to the longitudinal direction of the insulated stranded wire 2. The diameter Q of the mandrels 71, 72 is 20 mm (see FIGS. 14 and 15). The state shown in FIG. 13 is assumed to be the initial state. Then, the test is conducted as follows.

Referring to FIGS. 13 to 15, first, the insulated strand 2 is bent in the direction of arrow _R1 in FIG. At this time, the insulated strands 2 are bent along the outer circumferential surface 711 of the mandrel 71, as shown in FIG. The maximum bending angle θ ₁ of the insulated strands 2 is 90°. Next, after returning to the initial state shown in FIG. 13, the insulated strands 2 are bent in the direction of arrow _R2 in FIG. At this time, the insulated strands 2 are bent along the outer peripheral surface 721 of the mandrel 72, as shown in FIG. The maximum bending angle θ ₂ of the insulated strands 2 is 90°. The above operation was repeated, and the number of times each sample was bent until the strand 1 in the stranded insulated wire 2 broke was investigated.

Table 1 shows the experimental results of (1) and (2) above.

The state where the column of twist pitch/ _d2 of child stranded wire in Table 1 is ∞ (infinity) means the state in which the strands constituting the child strand are not twisted, that is, the strands are in the longitudinal direction of the child strand. It means the state of being arranged parallel to the direction. In addition, the expression "No breakage" in the column of the number of bends before breakage in Table 1 means that no breakage occurred after 10 million bendings and the test was discontinued.

Referring to Table 1, the strength of the connections of samples A to C in which the value of the twist pitch/d ₂ (diameter of the circumscribed circle of the child strands) of the child strands is 40 or less, which is within the range of the present disclosure, is , the value of the twist pitch/ _d2 of the child strands clearly exceeds the strength of the connections of samples D, E, H, K, N and Q, which are outside the scope of the present disclosure. This is considered to be because cracking of the core wire 101 during connection with the crimp terminal 80 was suppressed. In addition, regarding samples F and G in which the twist pitch/d ₁ (diameter of the circumscribed circle of the stranded wire) of the stranded wire is outside the range of 5 or more and 20 or less, which is the range of the present disclosure, other samples are Although it did not break even after repeated bending, it did break at an early stage. In addition, regarding sample G, since the surface of the stranded wire 1 had large irregularities, it was also confirmed that poor insulation occurred. From the above experimental results, it was confirmed that the stranded wire, insulated wire, and cable of the present disclosure not only improve bending resistance but also suppress cracking of the core wire when connected to a crimp terminal.

It should be understood that the embodiments and examples disclosed herein are illustrative in all respects and are not restrictive in any respect. The scope of the present invention is defined not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all changes within the scope.

1 stranded wire, 1A outer periphery, 2 insulated stranded wire, 3 insulated wire, 4 insulating layer, 4A outer periphery, 5 shield part, 5A outer periphery, 6 outer skin layer, 9 core, 10 child stranded wire, 10A center child stranded wire, 10B 1st peripheral stranded wire, 10C 2nd peripheral stranded wire, 11 insulating layer, 12 insulating layer, 70 bending test device, 71 mandrel, 72 mandrel, 73a jig, 73b jig, 80 crimp terminal, 81 conductor barrel, 82 insulation barrel, 83 main body, 91 first chuck, 92 second chuck, 100 strand, 100A central strand, 100B first peripheral strand, 101 core wire, 101A surface, 102 coating layer, 300 cable, 400 cable , 711 outer peripheral surface, 721 outer peripheral surface, P twist pitch, R ₁ arrow, R ₂ arrow, θ ₁ maximum bending angle, θ ₂ maximum bending angle.

Claims (12)

1. A stranded wire in which a plurality of child strands are twisted together,
   Each of the child stranded wires has the same structure in which a plurality of wires whose cross-sectional shape perpendicular to the longitudinal direction is circular with the same diameter are twisted together,
   The wire is
   steel core wire,
   A coating layer made of copper or copper alloy that covers the surface of the core wire,
   The twisting pitch of the child stranded wire is 40 times or more the diameter of the circumscribed circle of the child stranded wire,
   The stranded wire has a twist pitch that is 5 times or more and 20 times or less the diameter of the circumscribed circle of the stranded wire.
2. The stranded wire according to claim 1, wherein the diameter of the wire is 0.02 mm or more and 0.09 mm or less.
3. The stranded wire according to claim 1 or 2, wherein the core wire has a tensile strength of 1800 MPa or more and 4500 MPa or less.
4. The stranded wire according to any one of claims 1 to 3, wherein the carbon content of the steel constituting the core wire is 0.70% by mass or more and 0.95% by mass or less.
5. The stranded wire according to any one of claims 1 to 4, wherein in a cross section perpendicular to the longitudinal direction of the strand, the area of the coating layer with respect to the area of the strand is 20% or more and 80% or less. .
6. A stranded wire in which a plurality of child strands are twisted together,
   Each of the child stranded wires has the same structure in which a plurality of wires whose cross-sectional shape perpendicular to the longitudinal direction is circular with the same diameter are twisted together,
   The wire is
   steel core wire,
   A coating layer made of copper or copper alloy that covers the surface of the core wire,
   The twisting pitch of the child stranded wire is 40 times or more the diameter of the circumscribed circle of the child stranded wire,
   The twisting pitch of the stranded wire is 5 times or more and 20 times or less the diameter of the circumscribed circle of the stranded wire,
   The diameter of the core wire is 0.02 mm or more and 0.09 mm or less,
   The tensile strength of the core wire is 1800 MPa or more and 4500 MPa or less,
   The carbon content of the steel constituting the core wire is 0.70% by mass or more and 0.95% by mass or less,
   In a cross section perpendicular to the longitudinal direction of the strand, the area of the coating layer relative to the area of the strand is 20% or more and 80% or less,
   The plurality of child strands have a cross section perpendicular to the longitudinal direction of the strands,
   a central child strand located in the center;
   six first peripheral child strands arranged in contact with the center child strands so as to surround the outer peripheral side of the center child strands;
   The child strands each include 2 or more and 20 or less of the strands.
7. A stranded wire in which a plurality of child strands are twisted together,
   Each of the child stranded wires has the same structure in which a plurality of wires whose cross-sectional shape perpendicular to the longitudinal direction is circular with the same diameter are twisted together,
   The wire is
   steel core wire,
   A coating layer made of copper or copper alloy that covers the surface of the core wire,
   The twisting pitch of the child stranded wire is 40 times or more the diameter of the circumscribed circle of the child stranded wire,
   The twisting pitch of the stranded wire is 5 times or more and 20 times or less the diameter of the circumscribed circle of the stranded wire,
   The diameter of the core wire is 0.02 mm or more and 0.09 mm or less,
   The tensile strength of the core wire is 1800 MPa or more and 4500 MPa or less,
   The carbon content of the steel constituting the core wire is 0.70% by mass or more and 0.95% by mass or less,
   In a cross section perpendicular to the longitudinal direction of the strand, the area of the coating layer relative to the area of the strand is 20% or more and 80% or less,
   The plurality of child strands have a cross section perpendicular to the longitudinal direction of the strands,
   a central child strand located in the center;
   six first peripheral child strands arranged in contact with the center child strand so as to surround the outer peripheral side of the center child strand;
   12 second circumferential twisted wires arranged on the outer peripheral side of a region where the first circumferential twisted wires are arranged in contact with the first circumferential twisted wires,
   The child strands each include 2 or more and 20 or less of the strands.
8. The stranded wire according to any one of claims 1 to 7, wherein the coating layer is a plating layer.
9. The stranded wire according to any one of claims 1 to 8,
   An insulated wire, comprising: an insulating layer covering the outer periphery of the stranded wire.
10. a core in which a plurality of insulated strands are twisted together;
    a protective layer made of an insulator that covers the outer periphery of the core,
    Each of the insulated strands is
    The stranded wire according to any one of claims 1 to 8,
    An insulated wire, comprising: an insulating layer covering the outer periphery of the stranded wire.
11. The insulated wire according to claim 9;
    a shield made of a conductor arranged to surround the outer periphery of the insulated wire;
    A cable comprising: an outer skin layer made of an insulator and disposed so as to surround the outer periphery of the shield portion.
12. The insulated wire according to claim 10;
    a shield made of a conductor arranged to surround the outer periphery of the insulated wire;
    A cable comprising: an outer skin layer made of an insulator and disposed so as to surround the outer periphery of the shield portion.

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