CN111724929B - Coaxial cable for movable part - Google Patents

Abstract

The invention provides a coaxial cable for a movable part, which has electric characteristics suitable for long-distance transmission and is difficult to cause defects such as broken wires and the like even if a load reducing the diameter is applied. A coaxial cable (1) for a movable section is provided with an inner conductor (2), an insulator (3) surrounding the inner conductor (2), a wear-suppressing layer (4) surrounding the insulator (3) and formed by winding a tape member (41) in a spiral shape, an outer conductor (5) surrounding the wear-suppressing layer (4) and formed of a braided shield layer, and a sheath (6) surrounding the outer conductor (5), wherein the surface of the tape member (41) facing the insulator (3) and the surface of the tape member (41) facing the outer conductor (5) of the wear-suppressing layer (4) are made of a fluororesin.

Description

Coaxial cable for movable parts

technical field

The present invention relates to a coaxial cable for a movable part.

Background technique

In recent years, the market for human collaborative robots and small articulated robots has been expanding as a measure to improve productivity. As the robot cables used in such a robot, a cable for a movable part that is routed to a movable part of the robot and a cable for a fixed part that connects the robot and a control device are used. As the cable for the movable part, for example, a coaxial cable for the movable part that transmits a high-speed signal from a camera or the like is included.

Patent Document 1 is known as a conventional coaxial cable used in a movable part. The coaxial cable used in the movable portion of Patent Document 1 achieves improvement in high-speed signal transmission characteristics, bending resistance, and twisting resistance by making the insulator a three-layer structure.

prior art literature

patent documents

Patent Document 1: Japanese Patent No. 6394721

Contents of the invention

The problem to be solved by the invention

In recent years, robots with a wide movable range (moving range) have been put into practical use, and coaxial cables used for movable parts are also required to be able to perform long-distance transmission of tens of meters or more (for example, about 5m to 80m) . In order to reduce attenuation during long-distance transmission, it is necessary to increase the conductor cross-sectional area, but when the conductor cross-sectional area increases, the outer diameter of the coaxial cable used for the movable part also increases.

When the outer diameter of the coaxial cable used for the movable part is increased, it is difficult for the coaxial cable used for the movable part to move freely in the limited wiring space, and it is easy to use the coaxial cable used for the movable part when making a robot etc. move. A load that reduces the diameter (しごく) acts on the shaft cable. When a load is applied to reduce the diameter of the coaxial cable used for the movable part, lateral pressure friction occurs between the braided shield for the outer conductor and the insulator, and the insulator is worn and partially worn away. There is a characteristic Risk of undesirable conditions such as deterioration, short circuit or disconnection between inner and outer conductors.

Therefore, an object of the present invention is to provide a coaxial cable for use in a movable part that has electrical characteristics suitable for long-distance transmission and that is less prone to failure such as disconnection even when a load reducing the diameter is applied. .

Solution to the problem

In order to solve the above problems, the present invention provides a coaxial cable used in a movable part, which includes an inner conductor, an insulator covering the inner conductor, and a tape member wound around the insulator into a A wear-restraining layer formed in a spiral shape, an outer conductor formed of a braided shield covering the outer periphery of the wear-restraining layer, and a sheath covering the periphery of the outer conductor, wherein the wear-restraining layer includes A surface of the tape member facing the insulator and a surface facing the outer conductor are made of fluororesin.

Invention effect

According to the present invention, it is possible to provide a coaxial cable for use in a movable part that has electrical characteristics suitable for long-distance transmission and that is less prone to failure such as disconnection even when a load reducing the diameter is applied.

Description of drawings

1 is a diagram showing a coaxial cable for a movable part according to an embodiment of the present invention, wherein (a) is a cross-sectional view showing a cross section perpendicular to the length direction of the cable, and (b) is a part A therein Zoom in on the graph.

In FIG. 2 , (a) is a perspective view of the tape member, and (b) to (d) are cross-sectional views of the tape member.

Fig. 3 is a diagram illustrating a bending test.

Fig. 4 is a diagram illustrating a twist test.

Fig. 5 is a diagram illustrating a U-shaped bending test.

Fig. 6 is a diagram illustrating a diameter reduction test.

Explanation of reference signs

1...Coaxial cable for movable parts, 2...Inner conductor, 3...Insulator, 31...Unfilled extruded layer, 32...Foamed layer, 33...Non-foamed layer, 4...Abrasion suppression layer, 41... Tape part, 5...outer conductor, 51...inner braided shield, 52...outer braided shield, 6...sheath, 7...air layer.

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 is a diagram showing a coaxial cable for a movable part according to the present embodiment, in which (a) is a cross-sectional view showing a cross section perpendicular to the length direction of the cable, and (b) is an enlarged portion of A therein picture.

As shown in FIGS. 1( a ) and ( b ), the coaxial cable 1 used for the movable part is configured by sequentially providing an insulator 3 , an abrasion suppressing layer 4 , an outer conductor 5 and a sheath 6 around an inner conductor 2 . The coaxial cable 1 used for the movable part is, for example, a member for internal or external wiring of a robot used in a factory or the like, and at least a part thereof is arranged to pass through the movable part. The length of the coaxial cable 1 used for the movable part is, for example, about 5 m to 80 m. In addition, the coaxial cable 1 used for the movable part is used when transmitting a high-frequency signal with a bandwidth of, for example, 10 MHz to 6 GHz. The characteristic impedance of the coaxial cable 1 used for the movable part is, for example, 75Ω.

(inner conductor 2)

The internal conductor 2 is formed by twisting a plurality of bare metal wires made of copper or the like to obtain a sub-stranded wire, and further twisting a plurality of sub-stranded wires to obtain a composite stranded wire. The sub-twisted wires are composed of a plurality of bare metal wires which are collectively twisted, and the inner conductor 2 is formed by concentrically twisting a plurality of sub-twisted wires. The inner conductor 2 is constituted by complex twisting, which can improve the flexibility of the coaxial cable 1 used in the movable part, so that it can be easily wired. In addition, even if repeated bending and twisting are applied to the movable part, the bare metal wire can Wire breakage is less likely to occur, and the bending resistance and twist resistance are improved. In addition, by forming the inner conductor 2 as the composite twisted wire as described above, even if a load to reduce the diameter is applied to the coaxial cable 1 used for the movable part, disconnection and the like are less likely to occur, which is effective.

In order to obtain sufficient bending resistance and twist resistance, as the bare metal wire used for the inner conductor 2, a material having an elongation strength of 220 MPa or more and an elongation of 5% or more is used. In addition, in order to suppress the amount of attenuation during long-distance transmission, the conductor cross-sectional area of the inner conductor 2 can be made 0.75 mm ² or more. In this embodiment, for example, as the bare metal wire used for the internal conductor 2, a tinned annealed copper wire with a bare wire diameter of 0.08 mm is used, and 7 sub-stranded wires obtained by twisting 30 tinned annealed copper wires are used. Concentric twisting can constitute the inner conductor 2. The outer diameter of the inner conductor 2 at this time is about 1.41 mm, and the conductor cross-sectional area is about 1.04 mm ² .

(insulator 3)

The insulator 3 is formed to cover the inner conductor 2 . As the insulator 3 , it is desirable to use a material with a low dielectric constant in order to improve the transmission characteristics of high-frequency signals (more specifically, to prevent attenuation when transmitting high-frequency signals with a bandwidth of, for example, 10 MHz to 6 GHz over long distances). In this embodiment, a material having the following three-layer structure is used as the insulator 3: a non-substantial extruded layer 31 provided on the outer periphery of the inner conductor 2; The foam layer 32 and the non-foam layer 33 bonded to the outer periphery of the foam layer 32 .

The non-substantial extruded layer 31 is formed by extruding through a tube using a low dielectric constant non-foamed resin material. The non-substantial extruded layer 31 is formed by tube extrusion, so that when the non-substantial extruded layer 31 is formed, the resin material will not enter between the bare metal wires of the internal conductor 2, and between the internal conductor 2 and the non-substantial extruded layer 31 There will be some gaps between them. Thereby, the inner conductor 2 and the non-substantial extruded layer 31 can move independently of each other, and the bending resistance and twist resistance can be further improved. As the non-substantial extruded layer 31, a fluororesin material formed of, for example, FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), or the like can be used. In this embodiment, the non-substantial extruded layer 31 made of FEP and having a thickness of 0.3 mm can be formed.

The foam layer 32 is a low dielectric constant layer that ensures good electrical properties at high frequencies, and is made of foamed insulating resin material. The degree of foaming of the foam layer 32 may be 30% or more and 70% or less. This is because when the degree of foaming of the foamed layer 32 is less than 30%, the dielectric constant increases so that the long-distance transmission characteristics of high-frequency signals deteriorate, and when the degree of foaming exceeds 70%, the foamed layer 32 becomes If it is too soft, it will be easily crushed by external force when it is bent, and the transmission characteristics of high-frequency signals will be degraded. The foam layer 32 is formed of a resin material having a lower melting point than the resin material used for the non-substantial extruded layer 31 , and is not bonded to the non-substantiated extruded layer 31 . Thus, when the coaxial cable 1 used for the movable part follows the movement of the robot, the non-full extruded layer 31 with respect to the longitudinal direction of the coaxial cable 1 used for the movable part can be pressed against the foamed layer. 32 can move independently, so that the bending resistance and the twisting resistance can be further improved. As the foam layer 32, a material containing, for example, radiation-crosslinked foamed polyethylene or foamed polypropylene can be used. In this embodiment, a foam layer 32 with a thickness of 1.15 mm made of radiation cross-linked foamed polyethylene is formed.

The non-foamed layer 33 is a layer for protecting the foamed layer 32 and is formed by full extrusion using the same resin material as the foamed layer 32 . The non-foamed layer 33 is formed by full extrusion, whereby the foamed pores appearing on the surface of the foamed layer 32 are filled, and the non-foamed layer 33 and the foamed layer 32 are bonded together. As the non-foamed layer 33, a resin material including a non-foamed insulating resin having an elongation of 300% or more, a tensile strength of 15 MPa or more, and a dielectric constant of 2.5 or less can be used. The load when bending the coaxial cable 1 used for the movable part increases radially outward, and by increasing the elongation and tensile strength of the non-foamed layer 33, it is difficult to bend and twist the coaxial cable 1 repeatedly. Cracks are formed in the insulator 3 to further improve bending resistance and twist resistance. As the non-foamed layer 33 , for example, a material containing non-foamed polypropylene, radiation-crosslinked polyethylene, or the like can be used. In this embodiment, the non-foaming layer 33 may be formed of radiation-crosslinked polyethylene with a thickness of 1.25 mm. The outer diameter of the insulator 3 at this time is about 6.8 mm.

(Wear Inhibition Layer 4)

The wear suppression layer 4 is formed by winding a tape member 41 made of a fluororesin tape around the insulator 3 in a spiral shape. For example, it is conceivable to provide the wear-restraining layer 4 by extrusion molding, but in this case, the wear-restraining layer 4 becomes cylindrical, very hard, and becomes difficult to bend, resulting in the possibility of the coaxial cable 1 used for the movable part. Reduced flexibility. That is, in this embodiment, in order to suppress the decrease in the flexibility of the coaxial cable 1 for the movable part and to apply a load to reduce the diameter of the coaxial cable 1 for the movable part , to suppress the wear of the insulator 3 caused by lateral pressure wear between the outer conductor 5 made of a plurality of bare metal wires and the insulator 3 made of an insulating resin material, so that the insulator 3 is formed by fluororesin tape The tape member 41 is wound helically to form the abrasion inhibiting layer 4 . The tape member 41 is wound so as to partially overlap the fluororesin tape in the width direction, and is wound helically around the outer periphery of the insulator 3 . At this time, when the coaxial cable 1 used in the movable part is moved so as to reduce its diameter, the tape member 41 is overlapped and wound so that the surface of the insulator 3 does not protrude from the overlapping portion of the tape member 41. state. In addition, the overlapping portions of the tape members 41 are not bonded, and when the cable 1 used in the movable portion moves so as to reduce its diameter, the overlapping tape members 41 can slide. In addition, the fluororesin tape constituting the tape member 41 preferably has non-adhesive surfaces with respect to the insulator 3 and the outer conductor 5 , respectively. In addition, the term "a tape member made of a fluororesin tape" here means a tape formed uniformly of a fluororesin. In addition, in order to have the above-mentioned function and effect, it is preferable that the tape member 41 is overlapped and wound so that the overlapping portion of the fluororesin tape is 0.3 to 0.5 times the width of the fluororesin tape (for example, 15 mm to 35 mm).

According to the coaxial cable 1 for a movable part of the present embodiment, the above-mentioned abrasion suppressing layer 4 is provided between the insulator 3 and the outer conductor 5, whereby the coaxial cable 1 for a movable part is applied such that When the load is reduced in diameter, the coaxial cable 1 used for the movable part is subjected to lateral pressure, but the insulator 3 (especially the surface of the non-foamed layer 33 ) and the outer conductor 5 due to the lateral pressure can be suppressed. 3 wear and tear. That is to say, by having the wear-restraining layer 4, since the surface of the wear-restraining layer 4 in contact with the insulator 3 and the surface of the wear-restraining layer 4 in contact with the outer conductor 5 are less likely to wear due to lateral pressure, it is possible to improve the performance of the wear-restraining layer used in Durability when a load reducing the diameter is applied to the coaxial cable 1 of the movable part (hereinafter simply referred to as "durability against diameter reduction").

The wear suppression layer 4 preferably has a smooth surface (the coefficient of friction is lower than that of the insulator 3) so that when the coaxial cable 1 for the movable part is subjected to a load to reduce its diameter, the outer conductor 5 can resist The wear suppression layer 4 slides, and the durability against diameter reduction can be improved. Examples of the fluororesin tape used for the tape member 41 include ETFE (tetrafluoroethylene-ethylene copolymer) tape, PTFE (polytetrafluoroethylene) tape, and the like.

In addition, as the tape member 41 , it is preferable to use a material with a dielectric constant as low as possible in order to suppress the amount of attenuation of high-frequency signals. In this embodiment, the tape member 41 made of PTFE having a smooth surface and a low dielectric constant can be used.

The thickness of the tape member 41 may be not less than 25 μm and not more than 150 μm. This is because when the thickness of the tape member 41 is less than 25 μm, it is too thin, and it is easy to break due to back-and-forth abrasion. The flexibility of 1 is reduced. In this embodiment, the tape member 41 formed of, for example, a PTFE tape having a thickness of 100 μm can be used.

In the present embodiment, as shown in FIG. 2(a) and (b), the tape member 41 is formed using a fluororesin tape having one layer of fluororesin layer 411 (single layer), but it is not limited thereto. As long as the tape member 41 The surface 41a facing the insulator 3 and the surface 41b facing the outer conductor 5 may be made of fluororesin. For example, as shown in FIG.2(c), (d), the adhesive tape member 41 may be comprised with the multilayer structure of 2 or more layers. FIG. 2( c ) shows an example in which the fluororesin layer 411 is composed of multiple layers (two layers in the illustrated example) and the surfaces 41 a and 41 b are both made of fluororesin. The tape member 41 in FIG. 2( c ) can be formed, for example, by laminating a film made of a fluororesin. In addition, FIG. 2( d ) shows an example in which fluororesin layers 411 are provided on both surfaces of a substrate 412 so that both surfaces 41 a and 41 b are made of fluororesin. The adhesive tape member 41 of Fig. 2 (d) can be formed by coating fluororesin as a whole on both sides of the base material 412 and making it solidified so as to form the fluororesin layer 411, or, on both sides surfaces of the base material 412, the whole The formed film is formed by welding the film to the substrate 412 or the like.

(outer conductor 5)

The outer conductor 5 is a material for shielding external noise. In order to cover the outer circumference of the abrasion suppressing layer 4 and ensure the flexibility of the coaxial cable 1 for the movable part, the outer conductor 5 is constituted by a braided shield layer formed by braiding bare metal wires. In this embodiment, the outer conductor 5 is formed by laminating multiple layers of braided shielding layers. Here, the case where the outer conductor 5 is formed by laminating two braided shielding layers will be described, but the outer conductor 5 may be constituted by laminating three or more braided shielding layers. Hereinafter, the braided shielding layer provided on the inner side in the radial direction is referred to as the inner braided shielding layer 51 , and the braided shielding layer provided on the outer side in the radial direction is called the outer braided shielding layer 52 .

According to the coaxial cable 1 for a movable part of the present embodiment, the air layer 7 can be formed between the outer conductor 5 (inner braided shield layer 51 ) and the wear suppression layer 4 in a part of the circumferential direction. In order to form the air layer 7 , it is only necessary that the inner diameter of the inner braided shield layer 51 is larger than the outer diameter of the wear suppression layer 4 . In this embodiment, when forming the inner braided shielding layer 51, for example, a rod-shaped spacer assembled in a braiding forming device is arranged on the outer periphery of the wear suppression layer 4 along the cable length direction, and the bare metal wire is braided on the spacer. The inner braided shielding layer 51 is formed, and the inner braided shielding layer 51 is sequentially output from the braiding forming device so that the formed inner braided shielding layer 51 is separated from the spacer, whereby the air layer 7 can be formed. It should be noted that, even when such a manufacturing method is not performed, the bare metal wire of the inner braided shield layer 51 has a step portion (a step portion generated by overlapping a part of the tape member 41 in the width direction) of the tape member 41 . There is also a slight gap between them, but this gap is not included in the air layer 7 of the present invention. In addition, the shape of the spacer is not limited to a rod shape. The size of the air layer 7 is that the maximum distance between the surface of the wear-restraining layer 4 and the inner surface of the outer conductor 5 (the surface facing the surface of the wear-restraining layer 4 ) is in the range of 5 μm to 30 μm, which is called the wear resistance of the outer conductor 5. The state in which the surface of the layer 4 floats toward the sheath 6 side is suppressed. The maximum distance is measured by the following method: after the coaxial cable 1 for the movable part is cut at a predetermined position, the cross section (cross section perpendicular to the length direction of the cable) of the cut part is examined by an optical microscope or an electron microscope. When observing with a microscope, the maximum value of the linear distance from the surface of the wear suppression layer 4 to the inner surface of the outer conductor 5 was measured.

By forming the air layer 7 between the outer conductor 5 (inner braided shielding layer 51) and the wear suppression layer 4, it is possible to suppress the extrusion caused by the outer conductor 5, when the coaxial cable 1 used for the movable part is bent and shaken. Or when the diameter is reduced, the outer conductor 5 (inner braided shielding layer 51 ) and the wear suppression layer 4 can be easily moved relative to each other, thereby improving bending resistance, twist resistance, and durability against diameter reduction.

The outer braided shielding layer 52 is formed by braiding bare metal wires on the outer periphery of the inner braided shielding layer 51 in the same manner as a common braided shielding layer. This is because, when an air layer is formed between the inner braided shield layer 51 and the outer braided shield layer 52 , the contact resistance in the outer conductor 5 may increase and the characteristics may deteriorate.

In order to obtain sufficient bending resistance and twisting resistance, the bare metal wires used in both braided shielding layers 51 and 52 are made of a material having a tensile strength of 340 MPa or more and an elongation of 5% or more. In the present embodiment, as the bare metal wires used for the two braided shield layers 51 and 52 , a material made of a tin-plated copper alloy with a diameter of 0.08 mm can be used. In addition, the density of the two braided shielding layers 51, 52 is about 90%. It should be noted that the diameters of bare metal wires used in the two braided shielding layers 51 and 52 may be the same or different.

Further, in this embodiment, bare metal wire coated with lubricant can be used for the two braided shielding layers 51 and 52 . As a lubricant, for example, liquid paraffin can be used. Thereby, the outer conductor 5 and the wear suppression layer 4 can slide more easily, and the bending resistance, the twisting resistance, and the durability against diameter reduction can be further improved.

However, when the braiding angle of the inner braided shield layer 51 is large, there is a risk that the friction with the wear suppression layer 4 becomes severe. In addition, when the braiding angle of the outer braided shield layer 52 which is easily affected by bending is small, there is a risk that the bare metal wire becomes easily broken and the bending resistance decreases. Furthermore, when the braiding angles of the two braided shielding layers 51 and 52 are the same, there is a risk of increased wear between the two braided shielding layers 51 and 52 . Therefore, preferably, the braiding angle of the inner braided shielding layer 51 is smaller than the braiding angle of the outer braided shielding layer 52 . When the outer conductor 5 has three or more braided shielding layers, it is preferable that the braiding angle of the innermost braided shielding layer in the radial direction is smaller than the braiding angle of the braiding shielding layer arranged outside the braided shielding layer. It should be noted that the braid angle refers to the angle (absolute value) formed between the longitudinal direction of the bare metal wire and the longitudinal direction of the coaxial cable 1 used for the movable part.

(sheath 6)

The sheath 6 is formed to wrap around the outer conductor. As the sheath 6, for example, a material containing PVC (polyvinyl chloride) or polyurethane can be used. In this embodiment, the sheath 6 with a thickness of 1.0 mm is formed of PVC. Preferably, the sheath 6 is formed by tube extrusion so that the outer conductor 5 can move inside the sheath 6 . The outer diameter of the coaxial cable 1 for the movable part after the sheath 6 is formed is about 10 mm.

(Characteristics of the coaxial cable 1 used for the movable part)

The above-described coaxial cable 1 for a movable part was produced as an example, and subjected to a bending test, a twisting test, a U-bend test, and a diameter reduction test. In addition, as a comparative example, a coaxial cable for a movable part having the same structure as the coaxial cable for a movable part 1 of the embodiment except that the abrasion suppressing layer 4 was omitted was prepared, and the same procedure was carried out. test.

In the bending test, as shown in Fig. 3, the upper end of the coaxial cable 1 for the movable part is fixed so that the center line does not move, and the load is suspended from the lower end of the coaxial cable 1 for the movable part. With a hammer of W=5N (500gf), in the state where the bending jig 11 is installed so that the coaxial cable 1 used for the movable part bends left and right, apply a bend of ±90° in the left and right direction along the bending jig 11 for bending Coaxial cable 1 on the movable part. The bending radius R at which the coaxial cable 1 for the movable part is bent is about 5 times the outer diameter of the coaxial cable 1 for the movable part. The bending speed was 30 times/minute, and the number of times of bending was recorded as one reciprocation in the left-right direction. In addition, the bending of the coaxial cable 1 for the movable part is repeated, and the conduction detection of the inner conductor 2 is performed between both ends of the coaxial cable 1 for the movable part an appropriate number of times, and the attenuation from the initial The number of bending times when the variation of the characteristic impedance or the characteristic impedance is 10% or more is taken as the bending life. In the bending test, a bending life of 300,000 times or more was regarded as a pass, and a bending life of less than 300,000 times was regarded as a failure.

In the twist test, as shown in Fig. 4, the upper end of the coaxial cable 1 for the movable part is fixed so that the center line does not move, and it is fixed at one point of the coaxial cable 1 for the movable part. The collet 12 was not rotated, and a rotating collet 13 was installed at a spaced position above the collet 12 at a distance d (twisting length) = 500 mm. A hammer with a load W=5N (500gf) is hung from the lower end of the coaxial cable 1 used for the movable part. The rotary chuck 13 is rotated in this state, and twists of ±180° are repeatedly applied to the coaxial cable 1 for the movable part. The twisting speed was 30 times/minute, and the number of times of twisting was counted as one reciprocation in each direction. In addition, the twisting of the coaxial cable 1 for the movable part is repeated, and the conduction detection of the inner conductor 2 is performed between both ends of the coaxial cable 1 for the movable part an appropriate number of times, and the distance from the initial The number of twisting times at which the attenuation or the variation of the characteristic impedance is 10% or more is taken as the twisting life. In the twisting test, the case where the twisting life was more than 300,000 times was regarded as a pass, and the case where the twisting life was less than 300,000 times was regarded as a failure.

In the U-shaped bending test, as shown in FIG. 5 , one end of the coaxial cable 1 for the movable part is fixed on the fixed plate 14, and at the same time, the coaxial cable 1 for the movable part is moved along with the fixed plate 14. The plate 14 extends in a parallel direction, and after the extended coaxial cable 1 for the movable part is folded back in a U-shape, the other end of the coaxial cable 1 for the movable part is fixed on a 14 parallel to the mobile plate 15 . In this state, the moving plate 15 is repeatedly reciprocated with a stroke length L=1 m in a direction parallel to the extending direction of the coaxial cable 1 for the movable part. The bending radius of the coaxial cable 1 for the movable part is about 10 times the outer diameter of the coaxial cable 1 for the movable part. The stroke speed is 25 times/minute, and the number of strokes to make the moving plate 15 go back and forth once is recorded as 1 time. In addition, the conduction detection of the inner conductor 2 is performed between the two ends of the coaxial cable 1 used for the movable part at an appropriate number of times, and the stroke when the amount of attenuation or the amount of change in characteristic impedance from the initial stage is 10% or more The number of times is recorded as the U-shaped bending life. In the U-shaped bending test, the case where the U-shaped bending life is more than 1 million times is regarded as a pass, and the case where the U-shaped bending life is less than 1 million times is regarded as a failure.

In the diameter reduction test, as shown in Fig. 6, the coaxial cable 1 used for the movable part is arranged so as to extend in the horizontal direction, and at the same time, its both ends are extended downward through the trolley 16, and a load is suspended from both ends. Hammer 17 of W=5N (500gf). In addition, the coaxial cable 1 for the movable part between the trolleys 16 passes through two trolleys 18a, 18b provided on the trolley 18 so that they can reciprocate in the horizontal direction. One of the pulleys 18a rotates the coaxial cable 1 for the movable part introduced from the left in the figure and extends to the left by 180 degrees, and the other pulley 18b extends the coaxial cable 1 for the movable part introduced from the pulley 18a. The axis cable 1 rotates 180 degrees and extends to the right. By repeatedly reciprocating the trolley 18 left and right, the diameter of the coaxial cable 1 used in the movable part is repeatedly reduced. The diameter reduction speed is 10 times/min, and the diameter reduction times is recorded as 1 time with the trolley 18 reciprocating once. The pulleys 18a, 18b have a diameter of 160mm. In addition, conduction detection of the internal conductor 2 is performed between the two ends of the coaxial cable 1 for the movable part at an appropriate number of times, and the attenuation from the initial stage or the change in characteristic impedance is 10% or more. The number of diameters is recorded as the reduced diameter life. In the reducing test, the case where the reducing life is more than 100,000 times is regarded as a pass, and the case where the reducing life is less than 100,000 times is regarded as a failure.

Table 1 summarizes the results of the bending test, twisting test, U-shaped bending test, and diameter reduction test.

Table 1

Example comparative example Bending test qualified qualified twist test qualified qualified U-shaped bending test qualified qualified Reduction test qualified unqualified

As shown in Table 1, for the bending test, the twisting test and the U-shaped bending test, the examples and the comparative examples are all acceptable. However, in the diameter reduction test, the comparative example failed and the example passed. From this, it was confirmed that the durability against diameter reduction can be improved by having the wear suppressing layer 4 .

(Functions and Effects of Embodiments)

As described above, according to the coaxial cable 1 for a movable part of the present embodiment, the wear suppression layer 4 formed by winding the tape member 41 spirally around the insulator 3 is provided between the insulator 3 and the outer conductor 5 . , and the surface 41a facing the insulator 3 and the surface 41b facing the outer conductor 5 of the tape member 41 of the abrasion inhibiting layer 4 are made of fluororesin. As a result, even when the conductor cross-sectional area of the inner conductor 2 is increased in order to obtain electrical characteristics suitable for long-distance transmission, it is possible to realize improved durability against diameter reduction, and less likely to cause defects such as disconnection. part of the coaxial cable 1.

Summary of the implementation

Next, technical ideas grasped from the embodiments described above will be described with reference to the reference numerals and the like in the embodiments. However, each code|symbol etc. which are described below are not intended to limit the component in a claim to the member etc. which are shown in embodiment.

[1] A coaxial cable (1) for a movable part, comprising an inner conductor (2), an insulator (3) covering the inner conductor (2), and a tape member (41) around the insulator (3) ) a wear-inhibiting layer (4) wound in a helical shape, an outer conductor (5) formed of a braided shield covering the outer periphery of the wear-inhibiting layer (4), and a sheath covering the periphery of the outer conductor (5) (6) wherein the surface of the tape member (41) of the wear-restraining layer (4) facing the insulator (3) and the surface facing the outer conductor (5) are made of fluororesin.

[2] The coaxial cable (1) for a movable part according to the item [1], wherein in the abrasion suppressing layer (4), the tape member (41) is wound so that the tape member Parts of (41) in the width direction overlap each other, and the overlapping adhesive tape members (41) are movable relative to each other.

[3] The coaxial cable (1) for a movable part according to [1] or [2], wherein in the wear suppression layer (4), the friction coefficient of the surface of the tape member (41) is lower than the coefficient of friction of the surface of the insulator.

[4] The coaxial cable (1) for a movable part according to any one of [1] to [3], the insulator includes:

a non-full extruded layer (31) disposed on the periphery of said inner conductor (2),

a foamed layer (32) non-adhesively disposed on the periphery of said non-enriched extruded layer (31),

Adhesiveness is arranged on the non-foaming layer (33) of described foaming layer (32) periphery;

The inner conductor (2) and the non-enriched extruded layer (31) are movable independently of each other.

[5] The coaxial cable (1) for a movable part according to any one of [1] to [4], in a part in the circumferential direction, the outer conductor (5) and the abrasion suppressing layer ( 4) An air layer (7) is formed in between.

[6] The coaxial cable (1) for a movable part according to any one of [1] to [5], wherein the outer conductor (5) is formed by laminating multiple layers of braided shielding layers, and is arranged radially The braiding angle of the braided shielding layer (51) on the innermost side is smaller than the braiding angle of the braided shielding layer (52) arranged on its outer side with respect to the braided shielding layer (51).

[7] The coaxial cable (1) for a movable part according to any one of [1] to [6], wherein the outer conductor (5) has a tensile strength of 340 MPa or more and an elongation of 5%. The above bare metal wires are braided to form a braided shielding layer.

[8] The coaxial cable (1) for a movable part according to item [7], wherein the bare metal wire used for the outer conductor (5) is formed of a tin-plated copper alloy.

[9] The coaxial cable (1) for a movable part according to [7] or [8], wherein the bare metal wire used in the outer conductor (5) is coated with a lubricant.

[10] The coaxial cable (1) for a movable part according to any one of [1] to [9], wherein the inner conductor (2) has a conductor cross-sectional area of 0.75 mm ² or more.

[11] The coaxial cable (1) for a movable part according to any one of [1] to [10], using a sub-stranded wire obtained by twisting a plurality of bare metal wires, and further combining a plurality of The composite strand obtained by twisting the sub-stranded wires constitutes the inner conductor (2).

The embodiments of the present invention have been described above, but the above-described embodiments are not intended to limit the invention in the claims. In addition, it should be noted that combinations of all the features described in the embodiments are not necessarily means for solving the problems of the present invention.

The present invention can be appropriately modified and implemented within a range not departing from the gist.

Claims (12)

1. A coaxial cable for a movable part, comprising: inner conductor, wrapping an insulator around the inner conductor, a wear inhibiting layer formed by winding a tape member in a helical shape around said insulator, an outer conductor wrapped around the outer periphery of the wear inhibiting layer and formed of a braided shield, and a sheath surrounding the outer conductor; In the abrasion suppressing layer, the surface of the tape member facing the insulator and the surface facing the outer conductor are made of fluororesin. 2. The coaxial cable for a movable part according to claim 1, wherein, in the abrasion suppressing layer, the tape member is wound overlappingly so that a part of the width direction of the tape member overlaps each other, and the tape member overlaps with each other. The overlapping adhesive tape parts are movable with respect to each other. 3. The coaxial cable for a movable part according to claim 1 or 2, wherein, in the abrasion suppressing layer, a friction coefficient of a surface of the tape member is lower than a friction coefficient of a surface of the insulator. 4. The coaxial cable for a movable part according to claim 1 or 2, wherein the insulator comprises: a non-enriched extruded layer disposed on the periphery of said inner conductor, a foam layer non-adhesively disposed on the periphery of said non-enriched extruded layer, a non-foamed layer adhesively disposed on the periphery of the foamed layer; The inner conductor and the non-enriched extruded layer are movable independently of each other. 5. The coaxial cable for a movable part according to claim 1 or 2, wherein an air layer is formed between the outer conductor and the abrasion suppressing layer in a part in the circumferential direction. 6. The coaxial cable for a movable part according to claim 1 or 2, wherein the outer conductor is formed by laminating multiple layers of braided shielding layers, and the braiding angle of the innermost braided shielding layer is arranged radially. The braid angle is smaller than that of the braided shielding layer arranged on its outside with respect to the braided shielding layer. 7. The coaxial cable for a movable part according to claim 1 or 2, wherein the outer conductor is a braided metal bare wire having a tensile strength of 340 MPa or more and an elongation of 5% or more Shield formation. 8. The coaxial cable for a movable part according to claim 7, wherein the bare metal wire used in the outer conductor is formed of a tin-plated copper alloy. 9. The coaxial cable for a movable part according to claim 7, wherein the bare metal wire used in the outer conductor is coated with a lubricant. 10. The coaxial cable for a movable part according to claim 8, wherein the bare metal wire used in the outer conductor is coated with a lubricant. 11. The coaxial cable for a movable part according to claim 1 or 2, wherein the inner conductor has a conductor cross-sectional area of 0.75 mm ² or more. 12. The coaxial cable for a movable part according to claim 1 or 2, wherein a sub-stranded wire is obtained by twisting a plurality of bare metal wires, and further obtained by twisting a plurality of the sub-stranded wires composite strands to form the inner conductor.

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