JP7412126B2 - Flexible insulated wire - Google Patents

Description

The present invention relates to a bend-resistant insulated wire. More specifically, the present invention relates to a bend-resistant insulated wire that has excellent flexibility and is lightweight, and is particularly suitable for automotive wiring.

In recent years, as automobiles, industrial robots, electrical equipment, thermal equipment, etc. have become more sophisticated, the number of wiring locations has increased. The reliability required for the electric wires used for such wiring is also increasing. Furthermore, due to the demand for energy saving and compactness, there is also a demand for lighter weight electric wires themselves.

In response to these demands, for example, Patent Document 1 proposes an electric wire conductor for harnesses in which a stranded wire consisting of an aramid fiber bundle or string at the center and copper wires arranged around it is compressed and heat treated. . Further, Patent Document 2 relates to an overhead power transmission line, and a stranded conductor consisting of a tension member made of aramid fiber, glass fiber, etc. is arranged in the center, and a plurality of annealed copper wires are twisted on the outside thereof. An insulated wire has been proposed in which an insulated wire is provided with an insulating coating on the outside. Further, Patent Document 3 describes a structure in which a plurality of organic fibers having a maximum elongation of 10% or more are twisted around a center line made of copper or copper alloy formed to have a maximum elongation of 10% or more. , a small-diameter electric wire for a wire harness has been proposed in which the weight ratio of organic fiber to copper or copper alloy and the cross-sectional area of the thickness are specified.

Japanese Patent Application Publication No. 2008-91214 Japanese Unexamined Patent Publication No. 4-138616 Japanese Patent Application Publication No. 2003-123542

Each of the electric wires of the above-mentioned prior art has a fiber in the center, a metal wire around the outer periphery, and an insulator around the outer periphery. However, in these electric wires, some of the fibers tend to protrude from between the metal wires, which tends to deteriorate the appearance of the electric wires. Further, moisture or oil may adhere to the fibers, and the moisture or the like adhering to the fibers causes foaming or rough skin of the insulator when the insulator is provided around the outer periphery of the metal wire. Deterioration of the appearance of the electric wire, foaming of the insulator, and roughening of the surface of the wire cause local non-uniformity and reduce the bending life.

Further, in Patent Document 1, since the fiber core comes into contact with the extruded resin when covering the insulator, the fiber core may be affected by heat and may not be able to perform its function as a fiber core. Such a phenomenon is more likely to occur when the extrusion temperature is high, causing a decrease in the flex life.

The present invention has been made to solve the above problems. The purpose is to provide a bend-resistant insulated wire that has excellent flexibility and is lightweight, and is particularly suitable for automotive wiring.

The bend-resistant insulated wire according to the present invention is a stranded wire formed by twisting a fiber core and a plurality of metal wires having an outer diameter of 0.02 mm or more and 0.2 mm or less provided on the outer periphery of the fiber core. It is characterized in that it has a conductor and an insulator provided around the outer periphery of the stranded conductor, and the twisting pitch of the stranded conductor is 120 to 220 times the outer diameter of the metal wire.

According to this invention, by twisting the stranded wire conductor at a twisting pitch within the above range, the center position of the stranded wire conductor and the center position of the fiber core are shifted from each other. Due to this deviation, the load stress applied to the insulated wire is released, and the bending characteristics can be improved. Further, since the metal wires in the above range are twisted together to form a stranded conductor, the diameter of the stranded conductor can be reduced, and the entire insulated wire can be made smaller in diameter, lighter, and more flexible. As a result, it is possible to reduce stress concentration and improve tensile strength and bending properties using a large number of metal wires.

In the bend-resistant insulated wire according to the present invention, the number of metal wires constituting the stranded conductor is preferably 50 to 150. According to this invention, since the outer diameter of a stranded conductor made of a large number of metal strands becomes large, the length of the metal strands at the outer side of the stranded conductor is significantly longer than the length of the fiber core. Become. As a result, when stress is applied to the insulated wire and it bends, the significantly long metal wire can provide a margin for bending, and the bending characteristics can be improved.

In the bend-resistant insulated wire according to the present invention, the stranded conductor has an outer diameter of 1.6 mm or less. According to this invention, the stranded wire conductor having the above-described outer diameter can realize a thinner insulated wire with excellent bending resistance, and can achieve weight reduction.

In the bend-resistant insulated wire according to the present invention, the center position of the fiber core and the center position of the stranded conductor do not match. The center position refers to the center position calculated from the cross-sectional contour of the fiber core and the center position calculated from the cross-sectional contour of the stranded wire conductor, and it is preferable that the deviation between the two is 0.10 to 0.30 mm. . Such misalignment tends to cause the insulated wire to become flat when a load is applied to it, and the flat shape prevents stress from concentrating on a specific portion, allowing stress to escape and improving bending characteristics.

According to the present invention, it is possible to provide a bend-resistant insulated wire that has excellent flexibility, is lightweight, and is particularly suitable for wiring for automobiles.

1 is a schematic explanatory diagram showing an example of a bend-resistant insulated wire according to the present invention. FIG. 3 is an explanatory diagram of each dimension constituting the bend-resistant insulated wire. FIG. 3 is an explanatory diagram of a twisted state of a twisted wire conductor. FIG. 3 is an explanatory diagram showing an aspect of a bending test.

Hereinafter, the bend-resistant insulated wire according to the present invention will be explained with reference to the drawings. Note that the present invention is not limited to the illustrated embodiment.

[Bending-resistant insulated wire]
As shown in FIGS. 1 and 2, the bend-resistant insulated wire 10 (hereinafter also referred to as "insulated wire 10") according to the present invention includes a fiber core 1 and an outer diameter provided on the outer periphery of the fiber core 1. The stranded conductor 2 has a stranded conductor 2 formed by twisting a plurality of metal wires 3 having a thickness of 0.02 mm or more and 0.2 mm or less, and an insulator 4 provided on the outer periphery of the stranded conductor 2. The twist pitch P of No. 2 is 120 to 220 times the outer diameter of the metal wire 3. Note that "having" means that other configurations may be included as long as they do not impede the effects of the present invention. This means that plating or an insulating coating layer may be provided on the surface of the metal wire 3, and a fusion layer or the like may be provided on the outer periphery of the insulator 4.

In this bend-resistant insulated wire 10, by twisting the stranded conductor 2 at a twisting pitch P within the above range, the center position C2 of the stranded conductor 2 and the center position C1 of the fiber core 1 are shifted. Due to this deviation, the load stress applied to the insulated wire 10 is released, and the bending characteristics can be improved. Further, since the metal wires 3 in the above range are twisted together to form the stranded conductor 2, the diameter of the stranded conductor 2 can be reduced, and the entire insulated wire can be made smaller in diameter, lighter in weight, and more flexible. As a result, it is possible to reduce stress concentration by using a large number of metal wires 3 and improve tensile strength and bending properties.

Each component of the bend-resistant insulated wire will be explained in detail below.

(fiber core)
The fiber core 1 is an essential component located approximately at the center of the bend-resistant insulated wire 10, and is preferably a high-tensile body that functions as a winding core. As an example of the fiber core 1, a fiber yarn made by bundling a plurality of fibers is preferably used. It is preferable that the fibers constituting the fiber thread have strength and are heat resistant. Examples of fibers include polyester fibers such as Tetron (registered trademark), wholly aromatic polyamide fibers such as Kevlar (registered trademark), polyarylate fibers such as Vectran (registered trademark), and glass fibers. Further, the fiber core 1 may be formed by arbitrarily combining fiber yarns made of different materials or fiber yarns with different outer diameters.

The fiber core 1 has a concentric (perfect circular) or substantially concentric cross section made of fiber yarns made of assembled lines, twisted lines, or braided lines. At this time, in order to make the fiber core 1 more concentric or approximately concentric in cross section, it is more preferable to use the fiber threads as twisted wires. The outer diameter of the fiber core 1 is not particularly limited, but may be in the range of 0.1 to 1.0 mm, for example. Since the fiber core 1 made of fiber yarn is flexible and easily deformed, the outer diameter of the fiber core 1 is the outer diameter of the fiber core 1 when the fiber core 1 is perfectly circular, and the outer diameter of the fiber core 1 when the fiber core 1 is flat. Evaluate as the outer diameter converted from the cross-sectional area to the cross-sectional area of a perfect circle.

The fiber core 1 is usually expressed in fineness (dtex), which indicates the weight of fiber yarn, and 1 dtex is 1 g at a length of 10,000 m. The dtex range of the fiber core 1 of the present invention is preferably 110 to 2000 dtex. The fiber core 1 may be made of a single fiber thread or may be made of two or more types of fiber threads. When the fiber core 1 is composed of two or more types of fiber threads, the total dtex may be within the above range. If it is less than 110 dtex, bending durability tends to be insufficient. On the other hand, if it exceeds 2000 dtex, the outer diameter becomes large, which tends to affect workability and processability, and also results in insufficient bending durability.

The fiber core 1 is provided approximately at the center of the cross section of the bend-resistant insulated wire 10. "Substantially at the center" means that the center position C1 of the fiber core 1 is not located at the center position of the cross section of the bend-resistant insulated wire 10 (specifically, the center position C2 of the cross section of the stranded wire conductor 2), and the fiber core 1 This means that the center position C1 of the stranded wire conductor 2 and the center position C2 of the stranded wire conductor 2 are shifted from each other and do not match. The center position C1 of the fiber core 1 is a position calculated from the contour of the cross section of the fiber core 1, and means the so-called center of gravity position of the contour. The deviation between the center position C1 of the fiber core 1 and the center position C2 calculated from the cross-sectional contour of the stranded wire conductor 2, which will be described later, is preferably 0.10 to 0.30 mm. Such a deviation is caused by the fact that when a load is applied to the insulated wire 10, the insulated wire 10 tends to become flat, and the flat shape prevents stress from concentrating on a specific part, allowing the load stress applied to the insulated wire 10 to escape, resulting in bending characteristics. can be improved. Note that, after the stranded wire conductor 2 (described later) is provided around the fiber core 1, it is often difficult to maintain a circular or substantially circular cross-sectional shape due to the pressure applied from the stranded wire conductor 2. As shown in FIG. 1, the shape is likely to be deformed into a substantially triangular or substantially quadrangular shape.

(Twisted conductor)
The stranded wire conductor 2 is an essential component provided on the outer periphery of the fiber core 1, and is a stranded wire formed by twisting a large number of metal wires 3, as shown in FIG. By twisting a large number of metal wires 3 to form the stranded conductor 2, it is possible to shift the center position C1 of the fiber core 1 and the center position C2 of the stranded conductor 2 without making them coincide, and the weight is reduced. can also be realized.

The outer diameter of the metal wire 3 is preferably in the range of 0.02 mm or more and 0.2 mm or less. By doing so, a large number of metal wires 3 are twisted together to form the stranded wire conductor 2, so that the stranded wire conductor 2 can be made smaller in diameter, and the entire insulated wire can be made smaller in diameter, lighter in weight, and more flexible. As a result, it is possible to reduce stress concentration by using a large number of metal wires 3 and improve tensile strength and bending properties. If the outer diameter of the metal wire 3 is less than 0.02 mm, the metal wire itself becomes thin in diameter and a large number of wires are required, and the absolute value of the single wire strength becomes small. On the other hand, if the outer diameter of the metal wire 3 exceeds 0.2 mm, surface irregularities will become large.

The twist pitch P of the stranded wire conductor 2 is set to be 120 to 220 times the outer diameter d of the metal wire 3. By twisting the stranded conductor 2 at a twisting pitch P within this range, the center position C2 of the stranded conductor 2 and the center position C1 of the fiber core 1 are shifted. Due to this deviation, the load stress applied to the insulated wire 10 is released, and the bending characteristics can be improved. If P/d is less than 120 times, a load is applied to the conductor, which may cause wire breakage, and if P/d exceeds 220 times, the twist may become loose and the center position of the fiber core 1 may become unstable. be.

The number of metal wires 3 is preferably 50 to 150. If the number of metal wires 3 is less than 50, durability will be insufficient. On the other hand, when the number of metal wires 3 exceeds 150, the outer diameter becomes large, which tends to affect workability and processability. Furthermore, by configuring the number of metal wires 3 having the outer diameter range shown below within the above range, the overall outer diameter after the stranded wire conductor 2 is provided can be reduced, making the entire bend-resistant insulated wire thinner and lighter. can be realized.

Regarding the relationship between the twist pitch P of the metal wire 3 and the outer diameter of the stranded wire conductor 2, "twist pitch P (mm)" ÷ "outer diameter of the stranded wire conductor (mm)" is 5 times to 25 Preferably, the range is twice that. By setting it within this range, untwisting can be suppressed, variations in bending properties can be reduced, and the cross section can be easily rounded, so that good appearance and durability can be obtained. If this value is less than 5 times, the metal wire 3 will be wound tightly, so the stranded conductor 2 will tend to overlap more, and the metal wire 3 may float. As a result, the cross section may not be round, may become stiff and may not satisfy the bending characteristics, or may vary. On the other hand, if this value exceeds 25 times, the twist becomes loose and the threads may pop out, causing the thread to unravel during work. As a result, the cross section may not be round, and the bending properties may vary.

The metal wire 3 is not particularly limited in type as long as it is a metal with good conductivity, but may be a metal conductor with good conductivity such as a copper wire, a copper alloy wire, an aluminum wire, an aluminum alloy wire, a copper-aluminum composite wire, or the like. Preferred examples include those on which a plating layer is applied. Copper wire and copper alloy wire are particularly preferred. As the plating layer, a solder plating layer, a tin plating layer, a gold plating layer, a silver plating layer, a nickel plating layer, etc. are preferable. An insulating film (not shown) may be provided on the surface of the metal wire 3 if necessary. The type of insulating film is not particularly limited, but examples include common enamel films, such as urethane, polyester, polyesterimide (PEI), polyimide (PI), polyamideimide (PAI), and the like. The thickness is not particularly limited, but may be of type 1, type 2, or type 3 according to the general Japanese Industrial Standards (JIS C 3202:2014).

The outer diameter D2 of the stranded wire conductor 2 is preferably 1.6 mm or less. By doing so, the stranded wire conductor 2 having the outer diameter D2 can realize a reduction in diameter of the insulated wire 10 having excellent bending resistance, and can achieve weight reduction. The lower limit of the outer diameter of the stranded conductor 2 is not particularly limited, but can be set to 0.12 mm depending on the outer diameter of the fiber core 1 and the outer diameter and number of the metal wires 3 described above.

(Insulator)
The insulator 4 is provided to cover the stranded conductor 2. For example, after the stranded wire conductor 2 is provided, it can be formed by resin extrusion or the like so as to cover the outer periphery thereof. The constituent material of the insulator 4 may be any insulating and heat-resistant resin material, such as polyimide resin, acrylic resin, polyvinyl chloride (PVC), polyamide resin, polyester resin, fluorine resin, etc. can be mentioned. The thickness of the insulator 4 may be approximately 0.05 mm or more and 1.0 mm or less, but the thicker the better in order to improve the bending characteristics, and preferably approximately 0.1 mm to 0.3 mm, for example.

The relationship between the thickness of the insulator 4 and the outer diameter of the stranded conductor 2 is: "Thickness of the insulator 4 (mm)" ÷ "Outer diameter of the stranded conductor (mm)" is 0.15 to 0.30. It is preferable that it is in the range of . By keeping it within this range, both durability and flexibility can be achieved. If this value is less than 0.15, durability may be insufficient. On the other hand, if this value exceeds 0.30, flexibility may be insufficient.

Preferably, the thickness of the insulator 4 is uniform. However, since the insulator 4 is mainly formed by resin extrusion, the surface after the stranded wire conductor 2 is provided, which is a stage before resin extrusion, has small surface irregularities based on the metal wires 3. preferable. In the present invention, since the stranded conductor 2 formed by twisting a large number of metal wires 3 is provided so as to cover the fiber core 1, the unevenness on the surface of the stranded conductor 2 is reduced. Therefore, after the insulator 4 is formed on the outer periphery by resin extrusion, the surface unevenness of the outer diameter becomes small, and the thickness of the insulator 4 becomes uniform at each part. As a result, local stress concentration can be reduced and the bending life can be extended.

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that the present invention is not limited thereby.

[Example 1]
As the fiber core 1, a fiber thread (660 dtex, outer diameter of about 0.245 mm) made of aramid (polyamide) fiber was used. On this fiber core 1, 100 annealed copper wires each having an outer diameter of 0.08 mm were twisted together at a twisting pitch of 15 mm to form a stranded wire conductor 2 having an outer diameter of 0.97 mm. Next, an FEP resin (insulator 4) was formed with a thickness of 0.2 mm by melt extrusion, and an insulated wire 10 with an outer diameter of 1.4 mm was produced. In this insulated wire 10, "twisting pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 15.5, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 15.5. "diameter (mm)" is 0.21, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded wire conductor 2" is 9%, "cross-sectional area of one metal wire 3" ÷ The "cross-sectional area of fiber core 1" was 11%.

[Example 2]
Example 1 was performed except that 50 metal wires with an outer diameter of 0.08 mm were twisted at a twisting pitch of 11 mm to form a stranded wire conductor 2 with an outer diameter of 0.72 mm, and an insulated wire 10 with an outer diameter of 1.1 mm was produced. I did the same. In this insulated wire 10, "twisting pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 15.3, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 15.3. "diameter (mm)" is 0.28, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded wire conductor 2" is 19%, "cross-sectional area of one metal wire 3" ÷ The "cross-sectional area of fiber core 1" was 11%.

[Example 3]
Example 1 was performed except that 50 metal wires with an outer diameter of 0.11 mm were twisted at a twisting pitch of 14 mm to form a stranded wire conductor 2 with an outer diameter of 0.94 mm, and an insulated wire 10 with an outer diameter of 1.3 mm was produced. I did the same. In this insulated wire 10, "twisting pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 14.9, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 14.9. "diameter (mm)" is 0.21, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded wire conductor 2" is 10%, "cross-sectional area of one metal wire 3" ÷ The "cross-sectional area of fiber core 1" was 20%.

[Example 4]
Example 1 was performed, except that 150 metal wires with an outer diameter of 0.09 mm were twisted at a twisting pitch of 18 mm to form a stranded wire conductor 2 with an outer diameter of 1.17 mm, and an insulated wire 10 with an outer diameter of 1.6 mm was produced. I did the same. In this insulated wire 10, "twisting pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 15.4, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 15.4. "diameter (mm)" is 0.17, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded wire conductor 2" is 5%, "cross-sectional area of one metal wire 3" ÷ The "cross-sectional area of fiber core 1" was 13%.

[Example 5]
Example 1 was performed, except that 150 metal wires with an outer diameter of 0.05 mm were twisted at a twist pitch of 11 mm to form a stranded wire conductor 2 with an outer diameter of 0.76 mm, and an insulated wire 10 with an outer diameter of 1.2 mm was produced. I did the same. In this insulated wire 10, "twist pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 14.5, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 14.5. "diameter (mm)" is 0.26, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded wire conductor 2" is 16%, "cross-sectional area of one metal wire 3" ÷ The "cross-sectional area of fiber core 1" was 4%.

[Example 6]
A fiber thread (440 dtex, outer diameter approximately 0.20 mm) made of aramid (polyamide) fiber was used as the fiber core 1, and 50 metal wires each having an outer diameter of 0.08 mm were twisted at a twisting pitch of 11 mm to have an outer diameter of 0.72 mm. The procedure was the same as in Example 1, except that the stranded conductor 2 was an insulated wire 10 having an outer diameter of 1.1 mm. In this insulated wire 10, "twisting pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 15.3, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 15.3. "diameter (mm)" is 0.28, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded wire conductor 2" is 13%, "cross-sectional area of one metal strand 3" ÷ The "cross-sectional area of fiber core 1" was 16%.

[Example 7]
A fiber thread (440 dtex, outer diameter approximately 0.20 mm) made of aramid (polyamide) fiber was used as the fiber core 1, and 150 metal wires each having an outer diameter of 0.05 mm were twisted at a twisting pitch of 11 mm to have an outer diameter of 0.76 mm. Example 1 was carried out in the same manner as in Example 1, except that the stranded conductor 2 was used as an insulated wire 10 having an outer diameter of 1.2 mm. In this insulated wire 10, "twist pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 14.5, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 14.5. "diameter (mm)" is 0.26, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded wire conductor 2" is 11%, "cross-sectional area of one metal wire 3" ÷ The "cross-sectional area of fiber core 1" was 6%.

[Comparative example 1]
Example 1 was performed except that 30 metal wires each having an outer diameter of 0.08 mm were twisted at a twisting pitch of 9 mm to form a stranded wire conductor 2 with an outer diameter of 0.58 mm, and an insulated wire 10 with an outer diameter of 1.0 mm was prepared. I did the same. In this insulated wire 10, "twisting pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 15.5, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 15.5. "diameter (mm)" is 0.34, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded wire conductor 2" is 31%, "cross-sectional area of one metal wire 3" ÷ The "cross-sectional area of fiber core 1" was 11%.

[Comparative example 2]
A stranded conductor 2 with an outer diameter of 1.40 mm was obtained by twisting 220 metal wires with an outer diameter of 0.08 mm at a twist pitch of 21 mm, and an insulated wire 10 with an outer diameter of 1.8 mm was prepared. I did the same. In this insulated wire 10, "twist pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 15.0, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 15.0. "diameter (mm)" is 0.14, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded wire conductor 2" is 4%, "cross-sectional area of one metal wire 3" ÷ The "cross-sectional area of fiber core 1" was 11%.

[Comparative example 3]
Example 1 was performed, except that 160 metal wires with an outer diameter of 0.12 mm were twisted at a twist pitch of 27 mm to form a stranded wire conductor 2 with an outer diameter of 1.78 mm, and an insulated wire 10 with an outer diameter of 2.2 mm was produced. I did the same. In this insulated wire 10, "twisting pitch (mm)" ÷ "outer diameter of stranded conductor (mm)" is 15.2, and "thickness of insulator 4 (mm)" ÷ "outer diameter of stranded conductor" is 15.2. "diameter (mm)" is 0.11, "cross-sectional area of fiber core 1" ÷ "total cross-sectional area of stranded conductor 2" is 3%, "cross-sectional area of one metal wire 3" ÷ The "cross-sectional area of fiber core 1" was 24%.

[Bending test]
A bending test was conducted for each example and comparative example by the method shown in FIG. 4. In the bending test, as shown in FIG. 4, the insulated wire 10 with a length of 1000 mm produced in each example and comparative example is sandwiched between mandrels 42 and 42 with a radius of 5 mm, and a load 41 is applied to the lower end of the insulated wire 10. was attached, and the number of bends was measured in the direction perpendicular to the mandrel 42 at a rate of 30 times per minute, with one bend being 90 degrees on each side. The number of times of bending was evaluated as the number of times until the resistance value of the insulated wire 10 increased by 10%. The insulated wires of Examples 1 to 7 were all bent more than 20,000 times, and the measurement was terminated when the bending number was exceeded. On the other hand, in Comparative Examples 1 to 3, the number of bendings did not reach 20,000 times.

[Misalignment of center position]
The resulting bend-resistant insulated wire 10 was cured in a resin, a cross section was cut out, polished and observed under a microscope, and the distance L between the center position C1 of the fiber core 1 and the center position C2 of the stranded wire conductor 2 was measured. .

[Twisting pitch of stranded conductor]
Table 1 shows the relationship between the twist pitch P of the stranded conductor 2 and the outer diameter d of the metal wire 3 for the insulated wires of Examples 1 to 7 and Comparative Examples 1 to 3. The insulated wires of Examples 1 to 7 exhibiting good bending characteristics all had P/d within the range of 120 to 220.

1 Fiber core 2 Stranded conductor 3 Metal wire 4 Insulator 10 Flexible insulated wire A1 Cross-sectional area of fiber core A2 Cross-sectional area of stranded conductor A3 Cross-sectional area of one metal wire D1 Outer diameter of fiber core D2 Twisting Outer diameter of wire conductor D3 Outer diameter of bend-resistant insulated wire d Outer diameter of metal wire C1 Center position of fiber core C2 Center position of stranded conductor L Distance between C1 and C2 P Twisting pitch of stranded conductor T Insulator thickness of

Claims (2)

A fiber core made of twisted fiber threads with an outer diameter of 0.1 to 1.0 mm , and a metal wire provided on the outer periphery of the fiber core with an outer diameter of 0.02 mm to 0.2 mm. It has a stranded wire conductor made up of 50 to 150 twisted wires, and an insulator provided on the outer periphery of the stranded wire conductor, and an insulating film is not provided on the surface of the metal wire, and the stranded wire is The twisting pitch of the conductor is 120 to 220 times the outer diameter of the metal wire, and the center position of the fiber core and the center position of the twisted wire conductor do not match, and the difference therebetween is 0.10 to 0. A bend-resistant insulated wire characterized by having a thickness of .30 mm . The bend-resistant insulated wire according to claim 1 , wherein the stranded conductor has an outer diameter of 1.6 mm or less.

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