JPH09306245A - Shield cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To disperse stress against repeated flexion, improve resistance, and realize a magnetic shielding property at a reasonable cost by intervening powder in a clearance of a metal braid and acting it as a friction reducer. SOLUTION: Shield cables 1 are bundled by stranding plural internal conductors 2 coated by an insulator 3, after which a tape-shaped intermediate intervening material 4 is wound and tied as one cable. And, a ferrite powder of a magnetic material is mixed with a silicon rubber not cross-linked, a paste- like mixture is generated, and this mixture is applied on an intermediate intervening material 4. Further, a metal braid 5 is wound thereon by braiding it, and the mixture is filled into the mesh of the metal braid 5 while the outer circumference thereof is narrowed by means of a dice. Then, a silicon rubber mixture is cross-linked, and a mechanically stable rubber body 6 is molded and is certainly bonded with a metal wire 5a and a ferrite powder. And, an outer coat 7 is coated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shielded cable used as a transmission path for signals and the like, and more particularly to a shielded cable which improves repetitive bending property and shields electromagnetic noise.

[0002]

2. Description of the Related Art A flexible shielded cable in which a single core or multiple cores are shielded with a metal braid is widely used in signal transmission paths for connection between electronic devices and control of FA devices, which require flexibility. The cable has the characteristics of blocking the influence of electrical noise from the outside and blocking the generation of electrical noise from the cable itself. In such a shielded cable, a magnetic shielded property has been used at a place where it is necessary to block magnetic noise as well as electrical noise. As an example, 1)
The one that inserts the cable into the ring-shaped ferrite core,
2) A tape or foil coated with a magnetic material is wrapped around the cable, 3) A magnetic material is applied to the shield conductor, 4)
Some include a mixture of magnetic material in the internal insulator or sheath.

Conventionally, as a representative example of 4) of this type of shielded cable, there is one disclosed in Japanese Patent Application Laid-Open No. 63-170811, which is shown in FIG. FIG. 4 is a perspective view of a conventional shielded cable.

In the conventional shielded cable 100 shown in FIG. 4, a signal conductor 101, a dielectric 102 surrounding the signal conductor 101, a first shield layer 103 made of a metal braid surrounding the dielectric 102, and a first shield layer 103. Insulating synthetic resin intermediate layer 104 that surrounds the first shield layer 103 and is filled with metal particles, a second shield layer 105 formed of a metal braid that surrounds the intermediate layer 104, and an outermost synthetic resin jacket 106. And a configuration including.

In the conventional shielded cable 100 based on the above structure, the shield layers 103 and 105 shield the electric field, and the intermediate layer 104 containing metal particles shields the magnetic field.
Highly reliable electromagnetic wave shielding is obtained and high flexibility is provided.

[0006]

Since the conventional shielded cable is constructed as described above, when it is used in a place where the control wire or the like wired in the arm of the industrial robot is frequently bent, By repeatedly bending the cable at the same position on the cable, the metal wires that make up the braid can be sparsely and densely moved by the movement accompanying the bending of the metal braid that is arranged with a certain gap to ensure flexibility. However, there is a problem in that the stresses of (1) and (2) are concentrated on a part, and they are rubbed against each other and worn out, and eventually the wires are broken to affect the signal transmission. The only countermeasure against such a problem was to increase the strength of the metal braid, but this was contrary to flexibility and was difficult to implement.

In addition, also in terms of adding the conventional magnetic shield characteristics, in the case where the cable of 1) is inserted into the ferrite core, the storability in the wiring of the cable is deteriorated and the appearance is deteriorated. There is a problem that the cost is high because the manufactured core is assembled to the cable and manufactured. Further, when the tape or foil coated with the magnetic material of 2) is wound around the outer circumference of the cable, the flexibility of the cable is deteriorated, the installation location is limited, and the appearance is not good. Had. There are many technical difficulties in applying the magnetic material to the shield conductor of the above 3), and there is a problem that the equipment cost for processing increases. The above-mentioned 4) in which the magnetic substance is mixed in the inner insulator or the sheath has a problem that the friction with the mixed magnetic substance may damage the cable extrusion manufacturing machine. Further, the above 2), 3), and 4) have a problem that the amount of magnetic material used in the entire cable is large and the cost is high.

The present invention has been made in order to solve the above-mentioned problems, and it prevents wear against repeated bending, disperses stress to reduce damage to the metal braid, and improves durability. It is an object of the present invention to provide a shielded cable that can realize a magnetic shielding property at low cost and can have the same appearance as usual.

[0009]

SUMMARY OF THE INVENTION A shielded cable according to the present invention comprises a wire core in which one or a plurality of internal conductors are respectively covered with an insulator, an insulating intermediate interposition material covering the wire core, A flexible shielded cable including a metal braid wound on an intermediate interposer to shield the inner conductor, and an insulating outer jacket covering the outermost circumference, and ensuring flexibility of the metal braid. The powdery material is interposed in the gap in the braid provided for. As described above, in the present invention, the powdery material is present in the gap between the metal braids, and acts as an anti-friction agent between the metal braids, so that the direct contact between the metal braids is reduced even when repeated bending is performed. Wear of the metal braid is reduced, disconnection is less likely to occur, and reliability is improved.

Further, in the shielded cable according to the present invention, the powdery material is formed of a magnetic material, if necessary.
As described above, in the present invention, by disposing the magnetic material in the gap between the metal braids, the shielding effect of both the electric field shielding by the metal braiding and the magnetic field shielding by the magnetic material can be expected, and the electromagnetic interference can be surely prevented. At the same time, the appearance of the cable is exactly the same as usual, the flexibility is not impaired at all, special equipment is not required, it can be simplified, and the manufacturing process does not increase, and it can be manufactured at low cost.

In the shielded cable according to the present invention, the powdery material is held by a binding agent having elasticity so as not to move in the gap in the metal braid, if necessary. As described above, in the present invention, the binder having elasticity is interposed in the gap of the metal braid to hold the powdery material, so that the powdery material can be prevented from falling off and unevenly distributed, and can be bent repeatedly. Even if it is broken, the movement amount of the metal braid is made uniform and does not cause significant densification, the stress applied to the metal braid is dispersed, the metal braid is less likely to rub, and there is almost no wear. .

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

(One Embodiment of the Present Invention) Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 is a sectional view of the shielded cable according to the present embodiment, FIG. 2 is a schematic perspective view of the shielded cable according to the present embodiment, and FIG. 3 is a schematic configuration of a metal braid of the shielded cable according to the present embodiment. It is a figure.

In each of the above figures, a shielded cable 1 according to the present embodiment has a plurality of inner conductors 2 covered with an insulator 3 and a plurality of inner conductors 2 which are twisted together and wound around the outside. A tape-shaped intermediate interposer 4 which is covered and fixed by turns, a metal braid 5 wound on the intermediate interposer 4 and braided with a plurality of thin metal wires 5a in a mesh shape, and this metal Ferrite powder 8 filled in the gaps of the braid 5, rubber body 6 as a binder for holding the ferrite powders 8 in the gaps of the metal braid, and a synthetic resin jacket 7 covering the outside. It is the structure provided with.

In the method of manufacturing the shielded cable 1, first, a plurality of inner conductors 2 covered with an insulator 3 are twisted and bundled into one, and then a tape-shaped intermediate interposer 4 is wound,
Put together in one cable. Thereafter, the ferrite powder 8 as a magnetic material is kneaded with the uncrosslinked silicon rubber to form a paste-like mixture, and this mixture is applied onto the intermediate interposer 4. The metal braid 5 is wound on the applied mixture while being braided, and the mixture is packed into the mesh of the metal braid 5 while squeezing the outer periphery with a die. Then, the silicone rubber admixture is crosslinked to form a mechanically stable rubber body 6, which is securely bonded to the metal wire 5a of the metal braid 5 and the ferrite powder 8.

By making the mixture into a rubber body 6 by this cross-linking, it is possible to improve the workability such as attaching a connector after completion of the shielded cable 1 by eliminating the stickiness and to prevent the ferrite powder 8 from falling off. To do. Finally, the metal braid 5 is covered with a synthetic resin jacket 7 to complete the process. In addition to UV crosslinking, the silicone rubber may be crosslinked by a method such as a heat crosslinking method or a water crosslinking method at a temperature at which the insulator 3 of the shielded cable 1 and the intermediate interposer 4 are not thermally deteriorated. it can.

Next, the bent state and the magnetic shield state of the shielded cable according to the present embodiment based on the above configuration will be described. When the shielded cable 1 is bent,
The movement of the metal wire 5a forming the metal braid 5 is restricted by the rubber body 6 between the metal braids 5, the mesh of the metal braid 5 is uniformly spread on the outer peripheral side of the cable bending portion, and the metal braid 5 is formed on the inner peripheral side thereof. Since the meshes of N are uniformly narrowed, no significant density is generated, and the stress applied to the metal braid 5 is dispersed.
Further, since the ferrite powder 8 and the rubber body 6 are present in the gap, the metal braid 5 is less likely to be rubbed, is hardly worn, and is not broken, so that the reliability is greatly improved.

Further, with respect to the magnetic field, the ferrite powder 8 between the metal braids 5 captures the lines of magnetic force, converts the energy into heat or the like and dissipates it. That is, since the ferrite powder 8 acts as a magnetic pole at the end of the magnetic force line, the ferrite powder 8
The magnetic field disappears around and the high shielding effect is obtained.

As described above, the shielded cable according to the present embodiment has excellent durability, is less likely to be broken even by repeated bending, and is greatly improved in reliability. Further, both the electric field shielding effect by the metal braid 5 and the magnetic field shielding effect by the ferrite powder 8 can be expected, and the electromagnetic interference can be surely prevented, and the ferrite core or the tape / foil is not required on the outer circumference of the cable. The material cost and processing cost will be lower, the cable appearance will be the same as usual, and the flexibility will not change. Further, also in processing, since the mixture containing the ferrite powder 8 is packed while squeezing the metal braid 5, no special equipment is required, and the equipment cost is not required and the processing cost is not increased. Further, since the ferrite powder 8 as a magnetic body is small enough to enter the gap of the metal braid 5, the material cost can be suppressed and the manufacturing cost can be reduced.

In the shielded cable according to the above-mentioned embodiment, ferrite was used as the magnetic material powdery substance to be interposed in the gap of the metal braid 5, but magnetite, or ferrite or magnetite coated with another metal. It is also possible to adopt a configuration using a powder.

In the shielded cable according to the above-mentioned embodiment, silicon rubber is used as the rubber body. However, in addition to this, nitrile butyl rubber, chloroprene rubber, butyl rubber, ethylene propylene rubber or the like may be used. You can also

Further, in the shielded cable according to the above-mentioned embodiment, the ferrite powder 8 interposed in the gap of the metal braid 5 is held by the rubber body 6, but the ferrite powder 8 is not used. It is also possible to adopt a configuration in which the metal braid 5 can freely move in the gap.

[0022]

INDUSTRIAL APPLICABILITY As described above, in the present invention, the powdery material is present in the gap between the metal braids and acts as an anti-friction agent between the metal braids, so that the metal braids can be bent even if they are repeatedly bent. There is an effect that the direct contact of the wire is reduced, the wear of the metal braid is reduced, the wire is less likely to be broken, and the reliability is improved. Further, in the present invention, by disposing the magnetic material in the gap between the metal braids, the shielding effect of both the electric field shielding by the metal braiding and the magnetic field shielding by the magnetic material can be expected, and it is possible to reliably prevent electromagnetic interference. The external appearance of the cable is exactly the same as usual, the flexibility is not impaired at all, there is no need for special manufacturing equipment, and the manufacturing process can be simplified. Further, in the present invention, the binder having elasticity is interposed in the gap of the metal braid to hold the powdery material, so that the powdery material is prevented from falling off and unevenly distributed, and is repeatedly bent. Even if the movement amount of the metal braid is made uniform and the density is not significantly increased, the stress applied to the metal braid is dispersed and the metal braid is less likely to be rubbed and hardly wears. Have an effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a shielded cable according to an embodiment of the present invention.

FIG. 2 is a schematic configuration perspective view of a shielded cable according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a metal braid of a shielded cable according to an embodiment of the present invention.

FIG. 4 is a perspective view of a conventional shielded cable.

[Explanation of symbols]

 1, 100 Shielded cable 2 Inner conductor 3, 102 Insulator 4 Intermediate interposer 5 Metal braid 5a Metal wire 6 Rubber body 7, 106 Outer sheath 8 Ferrite powder 101 Signal conductor 103, 105 Shield layer 104 Intermediate layer

Claims (3)

[Claims] 1. A wire core in which one or a plurality of internal conductors are respectively covered with an insulator, an insulating intermediate interposer material covering the wire core, and the inner portion wound on the intermediate interposer material. A flexible shielded cable comprising a metal braid that shields the conductor and an insulating jacket that is coated on the outermost periphery, wherein a powder is provided in a gap in the braid provided for ensuring the flexibility of the metal braid. A shielded cable characterized by interposing the body. 2. The shielded cable according to claim 1, wherein the powdery material is formed of a magnetic material. 3. The shielded cable according to claim 1 or 2, wherein the powdery material is held in a gap in the metal braid with a binder having elasticity.