JP2022041383A - Multi-core cable and method for producing the same - Google Patents

Abstract

To improve the slidability of an insulated wire of a multi-core cable.SOLUTION: A multi-core cable 1 has a plurality of insulated wires 4 twisted together. The plurality of insulated wires 4 each have a conductor 2, and an insulating layer 3 that covers the periphery of the conductor 2. The insulating layer 3 has an inner peripheral face (3a) on the conductor 2 side and an outer peripheral face 3b on the opposite side from the inner peripheral face (3a). On the outer peripheral face 3b of the insulating layer 3, a plurality of inorganic fillers IF are dispersed. The plurality of inorganic fillers IF are spherical particles.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multi-core cable and a method for manufacturing the same, and more particularly to a multi-core cable including an insulated wire in which the outer periphery of a conductor is covered with an insulating layer.

A multi-core cable having a plurality of insulated wires having a conductor and an insulating layer covering the outer periphery of the conductive wire and having a plurality of insulated wires twisted together is known. When such a multi-core cable is applied to a robot cable, there is a problem that the bending life of the robot cable is shortened due to friction and wear generated between a plurality of insulated wires.

For example, Patent Document 1 describes a technique for reducing frictional resistance between two insulated wires and a sheath by providing a lubricant between the two insulated wires and a sheath that covers the outer periphery of these insulated wires. Is disclosed.

Further, Patent Document 2 discloses a PBT resin composition containing a polybutylene tereflorate resin, a polyether ester resin, and a silicone oil, and the PBT resin composition can be used as a coating resin material for electric wires. Is disclosed.

Further, Patent Document 3 discloses that a multi-core cable composed by twisting a plurality of insulated wires is used for a robot cable, and in order to improve the smoothness of the surface of the insulating layer of the insulated wires, the insulating layer is used. Discloses a technique for applying a polyester elastomer containing an organic high molecular weight silicone polymer.

Japanese Unexamined Patent Publication No. 2017-45731 Japanese Unexamined Patent Publication No. 9-3307 Japanese Unexamined Patent Publication No. 2008-218061

In order to suppress the shortening of the bending life of the robot cable, it is effective to reduce the friction and wear generated between the plurality of insulated wires by improving the slidability of the insulated wires. Therefore, it is conceivable to apply a fluororesin such as ETFE (ethylene tetrafluoride-ethylene copolymer resin) to the insulating layer of the insulated wire. However, such fluororesins are expensive.

Further, as in Patent Document 3 described above, it is also conceivable to improve the slidability by dispersing the silicone in the polyester elastomer. However, according to the study by the inventors of the present application, it has been found that an increase in the amount of silicone added causes discharge fluctuations, which causes a problem in the appearance of the cable. Therefore, it is difficult to sufficiently improve the slidability by the technique disclosed in Patent Document 3. The present invention has been made in view of the above problems, and an object of the present invention is to provide a multi-core cable capable of improving the slidability of an insulated electric wire.

The multi-core cable according to one embodiment includes a plurality of twisted insulated wires. Here, each of the plurality of insulated wires has a conductor and an insulating layer covering the outer periphery of the conductor, and the insulating layer is opposite to the inner peripheral surface on the conductor side and the inner peripheral surface. It has an outer peripheral surface on the side. Further, a plurality of inorganic fillers are dispersed on the outer peripheral surface of the insulating layer, and each of the plurality of inorganic fillers is spherical particles.

The method for manufacturing a multi-core cable according to an embodiment includes (a) a step of preparing a plurality of conductors, and (b) an inner peripheral surface on the conductor side and an inner surface on the outer periphery of each of the plurality of conductors. A step of forming a plurality of insulated wires by forming an insulating layer having an outer peripheral surface on the opposite side to the peripheral surface, (c) a plurality of inorganic particles on the outer peripheral surface of the insulating layer of each of the plurality of insulated wires. It includes a step of applying a filler, and (d) a step of twisting the plurality of insulated wires after the step (c). Here, after the step (c), the plurality of inorganic fillers are dispersed on the outer peripheral surface, and each of the plurality of inorganic fillers is spherical particles.

According to one embodiment, the slidability of the insulated wire of the multi-core cable can be improved.

It is a perspective view which shows the multi-core cable in Embodiment 1. FIG. It is sectional drawing which shows the multi-core cable in Embodiment 1. FIG. It is a perspective view which shows the insulated wire in Embodiment 1. FIG. It is sectional drawing which shows the insulated wire in Embodiment 1. FIG. It is a process flow which shows the manufacturing method of the multi-core cable in Embodiment 1. FIG.

Hereinafter, embodiments will be described in detail with reference to the drawings. In all the drawings for explaining the embodiment, the members having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted. Further, in the following embodiments, the same or similar parts will not be repeated in principle unless it is particularly necessary.

Further, in the drawings for explaining the embodiment, hatching may be omitted in order to make the configuration easy to understand.

(Embodiment 1)
<Structure of multi-core cable 1>
Hereinafter, the multi-core cable 1 according to the first embodiment will be described with reference to FIGS. 1 to 4. The multi-core cable 1 is used, for example, as a robot cable connected to each part of the robot.

FIG. 1 is a perspective view showing a multi-core cable 1. FIG. 2 is a cross-sectional view perpendicular to the extending direction of the multi-core cable 1. FIG. 3 is a perspective view showing the insulated wire 4. FIG. 4 is a cross-sectional view perpendicular to the extending direction of the insulated wire 4.

As shown in FIGS. 1 and 2, the multi-core cable 1 includes a plurality of twisted insulated wires 4, a tape layer 5 covering the outer periphery of the plurality of insulated wires 4, and a sheath 6 covering the outer periphery of the tape layer 5. And prepare.

In the present specification, an expression such as "tape layer 5 covering the outer periphery of the plurality of insulated wires 4" means that the tape layer 5 is located around the plurality of insulated wires 4, and the plurality of insulated wires 4 are located around the plurality of insulated wires 4. A plurality of insulated wires 4 and tapes, including a case where the insulated wires 4 and the tape layer 5 are in direct contact with each other, in a state where a space or other structure exists between the plurality of insulated wires 4 and the tape layer 5. It also includes the case where the layers 5 are adjacent to each other via the space or the other structure. Such a definition is not limited to the relationship between the plurality of insulated wires 4 and the tape layer 5, but also applies to the relationship between other structures such as the tape layer 5 and the sheath 6.

Each of the plurality of insulated wires 4 has a conductor 2 and an insulating layer 3 that covers the outer periphery of the conductor 2. As shown in FIGS. 3 and 4, the conductor 2 is an aggregate stranded wire composed of a plurality of twisted conductive wires 20, and the insulating layer 3 covers the outer periphery of the plurality of twisted conductive wires 20. Covering. In addition, an interposition 7 such as a cotton thread, a rayon, or a paper string may be provided in the gap between the insulated wires 4 covered with the tape layer 5.

When the multi-core cable 1 is bent, stress is concentrated on the conductor 2 at the bending point. Here, since the conductor 2 is a plurality of conductive wires 20 twisted together, the stress is dispersed with respect to the plurality of conductive wires 20, so that the bending life of the multi-core cable 1 can be improved.

The conductive wire 20 is a single wire made of a metal material such as copper or a copper alloy. Further, a plating layer made of a metal material such as tin or nickel may be formed on the surface of the conductive wire 20, and the metal material constituting the conductive wire 20 may be aluminum or an aluminum alloy.

The insulating layer 3 has an inner peripheral surface 3a on the conductor 2 side and an outer peripheral surface 3b on the side opposite to the inner peripheral surface 3a and on the tape layer 5 side. In other words, the conductor 2 is provided inside the inner peripheral surface 3a, and the tape layer 5 and the sheath 6 are provided outside the outer peripheral surface 3b.

The tape layer 5 is provided to prevent the multi-core cable 1 from losing its shape during manufacturing, and as the material of the tape layer 5, a resin film, a non-woven fabric, paper, or the like is used. The sheath 6 is made of a resin material, for example, polyethylene, polypropylene, vinyl chloride, silicone rubber or fluororesin.

Further, the insulating layer 3 is made of a thermoplastic resin. The thermoplastic resin is, for example, polyethylene, polypropylene, polyvinyl chloride, polybutylene terefurate, an elastomer of polybutylene terefralate, a polyamide 11, an elastomer of a polyamide 11, a polyamide 12, or an elastomer of a polyamide 12.

In the first embodiment, a plurality of inorganic filler IFs are dispersed on the outer peripheral surface 3b of the insulating layer 3. The plurality of inorganic filler IFs are coated on the outer peripheral surface 3b of the insulating layer 3 by the coating method.

Further, each of the plurality of inorganic filler IFs is spherical particles, for example, silica or alumina. When the insulating layer 3 is made of the above-mentioned thermoplastic resin, silica or alumina has a weak interaction with the thermoplastic resin, so that silica or alumina is easily distributed on the surface (outer peripheral surface 3b) of the thermoplastic resin. Become. The BET specific surface area of the plurality of inorganic filler IFs with respect to the outer peripheral surface 3b is 5 m ² / g or more and 25 m ² / g or less.

Since the plurality of inorganic filler IFs of such spherical particles are dispersed on the outer peripheral surface 3b of the insulating layer 3, the slidability of the insulated wire 4 can be improved. note that. Spherical particles include not only those that are strictly spherical, but also particles that differ by at least 95% (number average) of the maximum and minimum diameters of a representative sample by 10% or less.

By the way, the inventors of the present application have also considered applying talc on the outer peripheral surface 3b of the insulating layer 3. Talc is a powder made of hydrous magnesium silicate (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ). By applying talc, the slidability of the insulated wire 4 can be improved, and the shortening of the bending life of the multi-core cable 1 can be suppressed. However, according to the study by the inventors of the present application, the talc of the plate-shaped particles could not obtain a sufficient effect as compared with the inorganic filler IF of the spherical particles in terms of slidability and bending life. ..

By applying the inorganic filler IF of spherical particles, the spherical particles roll between the plurality of insulated wires 4 when the multi-core cable 1 is bent, so that a sufficient effect can be obtained from the viewpoint of slidability and bending life. Can be done.

The BET specific surface area of the plurality of inorganic filler IFs with respect to the outer peripheral surface 3b is 5 m ² / g or more and 25 m ² / g or less. The size of the inorganic filler IF with respect to the surface area is shown relatively large.

When the BET specific surface area is less than 5 m ² / g, aggregation of the inorganic filler IF occurs, and it becomes difficult to obtain sufficient slidability. On the other hand, when the BET specific surface area is larger than 25 m ² / g, a plurality of inorganic filler IFs are expressed as large particles on the outer peripheral surface 3b of the insulating layer 3, so that the appearance of the insulating layer 3 becomes difficult to be smooth and the outer peripheral surface 3 becomes difficult to smooth. The large particles act as protrusions on the surface 3b. Then, between the plurality of insulated electric wires 4, the protrusions may damage each other's insulating layer 3 and cause dielectric breakdown of the insulating layer 3.

On the other hand, in the first embodiment, the BET specific surface area of the plurality of inorganic filler IFs with respect to the outer peripheral surface 3b is 5 m ² / g or more and 25 m ² / g or less, so that these problems can be suppressed.

As described above, according to the multi-core cable 1 in the first embodiment, the slidability of the insulated wire 4 can be improved by the inorganic filler IF of spherical particles. Therefore, since the friction and wear generated between the plurality of insulated wires 4 can be reduced, even when the multi-core cable 1 is applied to a cable having a high bending frequency such as a robot cable, the multi-core cable 1 is used. It is possible to prevent the bending life of the cable from being shortened. Further, since it is not necessary to apply an expensive material such as fluororesin to the insulating layer 3 and the insulating layer 3 can be formed with a relatively inexpensive material, the multi-core cable 1 can be manufactured by an inexpensive method.

That is, according to the first embodiment, the reliability of the multi-core cable 1 can be improved, and the increase in the manufacturing cost of the multi-core cable 1 can be suppressed.

<Manufacturing method of multi-core cable 1>
Hereinafter, a method for manufacturing the multi-core cable 1 according to the first embodiment will be described with reference to FIG.

In step S1, a plurality of conductors 2 are prepared. Each of the plurality of conductors 2 can be formed by preparing a plurality of conductive wires 20 and twisting the plurality of conductive wires 20 together.

In step S2, the insulating layer 3 is formed. The insulating layer 3 is formed on the outer periphery of one conductor 2 by extrusion molding using an extruder. As a result, one insulated wire 4 is formed. Further, by repeating step S2 for the plurality of conductors 2, a plurality of insulated wires 4 can be obtained.

In step S3, a plurality of inorganic filler IFs are applied. By the coating method, a plurality of inorganic filler IFs can be dispersed on the outer peripheral surface 3b of the insulating layer 3. For example, the insulated wire 4 is immersed in a water tank filled with a solution containing a plurality of inorganic filler IFs of spherical particles. As a result, a plurality of inorganic filler IFs are applied and dispersed on the outer peripheral surface 3b of the insulating layer 3. Such a coating step is sequentially performed on a plurality of insulated wires 4.

Here, this coating step also serves as a cooling step after the formation of the insulating layer 3. Further, by applying the inorganic filler IF, the step of separately forming the lubricating layer on the outer peripheral surface 3b of the insulating layer 3 can be omitted. Therefore, this coating process can simplify the manufacturing process.

Further, in the step of the lubricating layer, powder is used as a lubricant, but when the terminals of the plurality of insulated wires 4 are processed, the powder flies, and the powder adheres to the exposed conductor 2, and a plurality of the powders adhere to the exposed conductor 2. The insulated wire 4 may be short-circuited. On the other hand, in the first embodiment, since the inorganic filler IF is applied using the water tank, such a fear does not occur.

In step S4, a plurality of insulated wires 4 in which a plurality of inorganic filler IFs are dispersed on the outer peripheral surface 3b are twisted together. Next, in step S5, the tape layer 5 is wound around the outer periphery of the plurality of twisted insulated wires 4. Next, in step S6, the sheath 6 is formed on the outer periphery of the tape layer 5 by extrusion molding using an extruder.

This completes the production of the multi-core cable 1.

Although the present invention has been specifically described above based on the embodiments, the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof.

For example, in the first embodiment, the case where the multi-core cable 1 is used as a robot cable is illustrated, but the multi-core cable 1 is used for transmitting an electric signal and is used for various electric devices. Can be applied to. For example, the multi-core cable 1 can also be applied to a cabtire cable.

1 Multi-core cable 2 Conductor 3 Insulation layer 3a Inner peripheral surface of insulation layer 3 3 Outer surface of insulation layer 3 4 Insulation wire 5 Tape layer 6 Sheath 7 Intervening 20 Conductive wire IF Inorganic filler

Claims (8)

Equipped with multiple twisted insulated wires,
Each of the plurality of insulated wires has a conductor and an insulating layer covering the outer periphery of the conductor.
The insulating layer has an inner peripheral surface on the conductor side and an outer peripheral surface on the opposite side to the inner peripheral surface.
A plurality of inorganic fillers are dispersed on the outer peripheral surface of the insulating layer,
A multi-core cable in which each of the plurality of inorganic fillers is spherical particles. In the multi-core cable according to claim 1,
The plurality of inorganic fillers are a multi-core cable coated on the outer peripheral surface. In the multi-core cable according to claim 1,
A multi-core cable in which each of the plurality of inorganic fillers is silica or alumina. In the multi-core cable according to claim 3,
The insulating layer is a multi-core cable made of a thermoplastic resin. In the multi-core cable according to claim 4,
The thermoplastic resin is a polycore, which is polyethylene, polypropylene, polyvinyl chloride, polybutylene terefurate, an elastomer of polybutylene terefurate, an elastomer of polyamide 11, a polyamide 11, a polyamide 12, or an elastomer of polyamide 12. cable. In the multi-core cable according to claim 5,
A multi-core cable having a BET specific surface area of the plurality of inorganic fillers with respect to the outer peripheral surface of 5 m ² / g or more and 25 m ² / g or less. In the multi-core cable according to claim 1,
A multi-core cable further comprising a tape layer covering the outer periphery of the plurality of insulated wires and a sheath covering the outer periphery of the tape layer. (A) Step of preparing a plurality of conductors,
(B) A step of forming a plurality of insulated wires by forming an insulating layer having an inner peripheral surface on the conductor side and an outer peripheral surface on the opposite side to the inner peripheral surface on the outer periphery of each of the plurality of conductors. ,
(C) A step of applying a plurality of inorganic fillers to the outer peripheral surface of the insulating layer of each of the plurality of insulated wires.
(D) After the step (c), the step of twisting the plurality of insulated wires.
Equipped with
After the step (c), the plurality of inorganic fillers are dispersed on the outer peripheral surface, and the inorganic filler is dispersed.
A method for manufacturing a multi-core cable, wherein each of the plurality of inorganic fillers is spherical particles.

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