JP6079675B2 - coaxial cable - Google Patents

Description

  The present invention relates to a coaxial cable having a core material inside an inner conductor.

  In recent years, in coaxial cables in which a foamed insulation layer, outer conductor, and sheath are coaxially provided in this order on the outer circumference of the inner conductor, the inner conductor is made of copper tape on the outer circumference of the rod from the viewpoint of flexibility, weight reduction, and cost reduction. A vertically wound one has been proposed (for example, see Patent Document 1).

  The coaxial cable described in Patent Document 1 includes a plastic rod, an inner conductor made of a copper tape that is vertically wound around the outer periphery of the plastic rod via an adhesive layer, and a butt portion is welded along the longitudinal direction, and an inner conductor A foamed dielectric layer provided on the outer periphery of the conductor, a tubular metal outer sheath provided on the outer periphery of the foamed dielectric layer, and a jacket provided on the outer periphery of the tubular metal outer sheath via an adhesive layer. Flexibility can be enhanced by forming the inner conductor on the plastic rod.

JP-T-2001-516123

  However, according to the conventional coaxial cable, the adhesive leaks from the adhesive layer due to heating during welding of the copper tape, and there is a risk that the attenuation of the signal transmitted by the leaked adhesive increases.

  Therefore, an object of the present invention is to provide a coaxial cable that is lightweight and excellent in flexibility and capable of forming an internal conductor without using an adhesive or welding.

  For the purpose of solving the above-mentioned problems, the present invention provides a core material made of a rubber material, an inner conductor provided on the outer periphery of the core material, and an outer member provided on the outer periphery of the inner conductor via an insulator. The rubber material comprising the conductor and constituting the core material provides a coaxial cable having an elongation smaller than that of the inner conductor and a tensile strength larger than the tensile strength of the inner conductor.

Rubber material constituting the core material, elongation 20-50%, the tensile strength is 200 to 400 N / mm ^2, wherein the inner conductor extends is 30% to 60% and a tensile strength of 100~300N / mm ² is preferable. The rubber material constituting the core material may be formed by containing a predetermined amount of sulfur and a predetermined amount of ebonite in the rubber component.

  The inner conductor may be a copper tube having an outer diameter of 5 mm or more and a thickness of 200 to 300 μm. Further, the inner conductor may be formed by vertically winding a copper tape so as to wrap the core material, and directly contacting the outer peripheral surface of the core material by passing the butt portion of the copper tape through a die without welding. Good.

  According to the present invention, it is lightweight and excellent in flexibility, and an internal conductor can be formed without using an adhesive or welding.

FIG. 1 is a front view showing a schematic configuration of a coaxial cable according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the coaxial cable shown in FIG. FIG. 3 is a diagram illustrating an example of a process of forming an internal conductor on the outer periphery of the core material illustrated in FIG. 1. FIG. 4 is a cross-sectional view of a coaxial cable according to the first modification of the present invention. FIG. 5 is a perspective view showing a schematic configuration of a coaxial cable according to Modification 2 of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, about the component which has the substantially same function, the same code | symbol is attached | subjected and the duplicate description is abbreviate | omitted.

[Embodiment]
FIG. 1 is a front view showing a schematic configuration of a coaxial cable according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the coaxial cable shown in FIG.

  The coaxial cable 1 includes a core material 2, an inner conductor 3 provided on the outer periphery of the core material 2, an outer conductor 5 provided on the outer periphery of the inner conductor 3 via an insulator 4, and a periphery of the outer conductor 5. And a sheath 6 as an insulating protective layer.

  The core material 2 is a cylindrical hollow core material made of a rubber material. The rubber material constituting the core material 2 includes, for example, a predetermined amount of sulfur and a predetermined amount of ebonite in the rubber component. More specifically, the rubber material constituting the core material 2 is, for example, natural rubber, epoxy-modified natural rubber, isobutyl rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, styrene isobrene butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber. And diene rubbers such as butyl rubber. The diene rubber may be used alone or in combination of two or more. Among these, natural rubber, isobutyl rubber, and butadiene rubber are preferable. 10 to 25 parts by mass of sulfur, 10 to 20 parts by mass of carbon black, and 3 to 30 parts by mass of an ebonite powder having an average particle size of 500 μm or less with respect to 100 parts by mass of the rubber component.

The rubber material that constitutes the core material 2 is preferably a rubber material that has a smaller elongation and a higher tensile strength than the conductive material that constitutes the inner conductor 3 in consideration of the flexibility and the dicing process. The elongation of the rubber material is preferably 20 to 50%, more preferably 20 to 30%. If the elongation is less than 20%, the flexibility of the coaxial cable 1 is lowered, and if the elongation exceeds 50%, the dicing process is hindered. Tensile strength of the rubber material is preferably ^{200~400N / mm 2, 200~300N / mm} 2 is more preferable. When the tensile strength is less than 200 N / mm ² , the die drawing process is hindered. When the tensile strength exceeds 400 N / mm ² , the flexibility is lowered.

The inner conductor 3 is made of a conductive material such as copper (oxygen-free copper, tough pitch copper, etc.), copper alloy, aluminum, aluminum alloy, for example. Of these conductive materials, copper is preferable in terms of conductivity and workability. The thickness of copper is preferably 200 to 300 μm in order to suppress deformation and disconnection during cable extrusion manufacturing and to reduce the weight. 100-300 N / mm < ² > is preferable and, as for the tensile strength of copper, 200-300 N / mm < ² > is more preferable. Further, the elongation of copper is preferably 30 to 60%, and more preferably 40 to 60%. The inner conductor 3 preferably has an outer diameter of 5 mm or more in order to transmit power and signals, for example. The inner conductor 3 is formed by, for example, vertically winding a copper tape so as to wrap the core material 2 and passing the butt portion of the copper tape through a drawing die without welding, thereby directly contacting the outer peripheral surface of the core material 2. That is, the inner conductor 3 is formed on the outer periphery of the core material 2 without an adhesive layer. Here, the measuring method of the elongation and tensile strength of the rubber material constituting the core material 2 is based on JIS standard K6251. The method for measuring the elongation and tensile strength of copper or copper tape constituting the inner conductor 3 is in accordance with JIS standard Z2251.

  The insulator 4 is preferably made of a material having a low dielectric constant and dielectric loss tangent in order to reduce transmission loss. As such a material, for example, an insulating resin such as polytetrafluoroethylene (PTFE), polyethylene, perfluoroalkoxyalkane (PFA) can be used, and in order to further reduce the dielectric constant and dielectric loss tangent, foamed polyethylene, foamed foam, A foamed insulating resin such as Teflon (Teflon is a registered trademark) can be used.

  The outer conductor 5 is, for example, an annular corrugated copper tube in which large diameter portions 5a and small diameter portions 5b are alternately formed along the cable longitudinal direction.

  The sheath 6 is made of, for example, polyethylene resin, ethylene-vinyl acetate polymer, fluorine resin, silicone resin, or the like.

(Manufacturing process of coaxial cable 1)
Next, an example of a manufacturing process of the coaxial cable 1 will be described with reference to FIG.

  FIG. 3 is a diagram illustrating an example of a process of forming the inner conductor 3 on the outer periphery of the core material 2. The inner conductor 3 is, for example, vertically wound with a copper tape 30 having a thickness of 200 to 300 μm so as to wrap the core material 2, and the butted portion 30 a of the copper tape 30 is not welded but passed through the opening 50 a of the drawing die 50. And compressed to a predetermined outer diameter. As a result, the copper tape 30 is in close contact with the outer peripheral surface of the core material 2 to form the internal conductor 3.

  Thereafter, the foaming agent is injected into the mixture of the foam nucleating agent and polyethylene and kneaded. As the foaming agent, an inert gas such as nitrogen gas, carbon dioxide gas, or argon gas may be used alone or a mixture of two types. Next, the kneaded material is supplied from the extrusion head to the outer periphery of the inner conductor 3 to form the insulator 4 made of foamed polyethylene. Next, the copper tape is vertically wound so as to wrap the insulator 4, the butted portions of the copper tape are welded, and then an annular corrugation process is performed to form an annular corrugated copper tube as the outer conductor 5 on the outer periphery of the insulator 4. Next, the sheath 6 is formed on the outer periphery of the outer conductor 5 by a known / conventional method.

(Operation and effect of the embodiment)
According to the present embodiment, the following operations and effects are achieved.
(1) Since the core material 2 is formed from a rubber material whose elongation is smaller than that of the internal conductor 3, the core material 2 can withstand the tension during the drawing of the die, and the internal conductor 3 can be used without using an adhesive or welding. It can be brought into close contact with the outer peripheral surface of the core material 2.
(2) Since the core material 2 is made of a rubber material whose tensile strength is larger than the tensile strength of the inner conductor 3, and the inner conductor 3 is formed on the outer periphery of the core material 2, the inner conductor only of the copper pipe without the core material 2 Flexibility and flexibility are improved.
(3) Even if the outer diameter of the inner conductor 3 is increased, since a thin copper tube is used as the inner conductor 3, the weight of the power cable can be reduced.
(4) Since an annular corrugated copper pipe is used as the outer conductor 5, the flexibility is higher than that of a smooth copper pipe.

[Modification 1]
FIG. 4 is a cross-sectional view of a coaxial cable according to the first modification of the present invention. In the above-described embodiment, a pipe-shaped material is used as the core material 2, but the first modification uses a solid cylindrical material as the core material 12. According to the modified example 1, the effects (1) to (4) of the present embodiment can be achieved, and the tensile force at the time of dicing can be increased as compared with the cylindrical core material 2.

[Modification 2]
FIG. 5 is a perspective view of a coaxial cable according to the second modification of the present invention. In the above embodiment, the case where the foamed insulating resin is used as the insulator 4 has been described. However, in the second modification, the support member 7 made of a spiral resin and the surrounding air layer are used as the insulator. It is. The support member 7 supports the outer conductor 5 from the inner conductor 3 side. According to the second modification, the effects (1) to (4) of the present embodiment can be achieved, and the flexibility can be increased as compared with the case where the foamed insulating resin is used as the insulator 4.

[Modification 3]
The coaxial cable according to Modification 3 of the present invention is the same as that of Modification 2 except that a slot for radiating electromagnetic waves is formed in the outer conductor, a suspension line is provided in parallel with the outer conductor, and the outer conductor and the suspension line are collectively bundled with a sheath. This is a leaky coaxial cable that is covered. In the third modification, a part of the signal transmitted through the cable is emitted as a radio wave from the slot to the outside and leaked, thereby enabling communication between the mobile body and the fixed station. This modification 3 also has the same effect as this embodiment. Note that the hanging line need not be provided.

  The embodiments of the present invention are not limited to the above-described embodiments, and various embodiments are possible. The outer conductor may be a metal pipe such as a smooth copper pipe. The outer conductor may be a spiral Golgate tube. Also by these, the same effect as this embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Coaxial cable, 2 ... Core material, 3 ... Internal conductor, 4 ... Insulator, 5 ... External conductor, 5a ... Large diameter part, 5b ... Small diameter part, 6 ... Sheath, 7 ... Support member, 12 ... Core material, 30 ... Copper tape, 30a ... butting part, 50 ... drawing dies, 50a ... opening

Claims (5)

A core material formed from a rubber material;
An inner conductor provided on the outer periphery of the core material;
An outer conductor provided through an insulator on the outer periphery of the inner conductor,
The rubber material constituting the core material has an elongation smaller than the elongation of the inner conductor and a tensile strength larger than the tensile strength of the inner conductor.
coaxial cable. Rubber material constituting the core material, elongation 20-50%, the tensile strength is 200 to 400 N / mm ^2,
The inner conductor has an elongation of 30 to 60% and a tensile strength of 100 to 300 N / mm ² .
The coaxial cable according to claim 1. The rubber material constituting the core material includes a predetermined amount of sulfur and a predetermined amount of ebonite in the rubber component.
The coaxial cable according to claim 1 or 2. The inner conductor is a copper tube having an outer diameter of 5 mm or more and a thickness of 200 to 300 μm.
The coaxial cable according to any one of claims 1 to 3. The inner conductor is formed by winding the copper tape vertically so as to wrap the core material, and directly contacting the outer peripheral surface of the core material by passing the butt portion of the copper tape through a die without welding.
The coaxial cable according to claim 4.

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