Cable

Abstract

To provide a cable which improves resistance against operation such as bending.SOLUTION: A cable 1 includes an inner layer 3 where signal lines 3a as a plurality of first electric wires are arranged in a cable peripheral direction, a shield layer 6 which coats the periphery of the inner layer 3, and is composed of an alternating woven braid in which metal element wires and fiber element wires are constituted by braiding, an outer layer 7 that coats the periphery of the shield layer 6, and in which power source lines 71 as a plurality of second electric wires in the cable peripheral direction are arranged, and sheath 9 coating the periphery of the outer layer 7.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a cable.

Background Art

[0002] As cables to be wired to devices such as industrial robots, for example, there are Patent Documents 1 and 2. In the cables described in Patent Documents 1 and 2, a plurality of electric wires have a collective core in which they are arranged in multiple layers along the cable diameter direction, and a holding tape and a sheath are sequentially arranged around the collective core.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In devices such as industrial robots, there are movable parts where operations such as bending, twisting, and swinging (referred to as operations such as bending) are repeatedly performed. For cables wired through this movable part, high durability against operations such as bending is required. However, in a cable having a collective core in which a plurality of electric wires are arranged in multiple layers, particularly for the electric wires arranged on the inner side in the cable diameter direction, a force is applied to push them inward in the cable diameter direction from other members such as the electric wires arranged on the outer side in the cable diameter direction. When such operations as bending are repeatedly applied to the cable in such a state, the electric wires are likely to break, and the resistance to operations such as bending decreases.

[0005] Therefore, an object of the present invention is to provide a cable with improved resistance to operations such as bending.

Means for Solving the Problems

[0006] The present invention aims to solve the above problems, and provides a cable comprising: an inner layer in which a plurality of first electric wires are arranged along the circumferential direction of the cable; a shield layer covering the periphery of the inner layer and formed of an intertwined braid in which metal strands and fiber strands are braided; an outer layer covering the periphery of the shield layer and in which a plurality of second electric wires are arranged along the circumferential direction of the cable; and a sheath covering the periphery of the outer layer.

Effect of the Invention

[0007] According to the present invention, it is possible to provide a cable with improved resistance to operations such as bending.

Brief Description of the Drawings

[0008]

Figure 1

Embodiment for Carrying out the Invention

[0009] [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0010] FIG. 1 is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of a cable 1 according to the present embodiment. The cable 1 is used, for example, as internal wiring in a device such as an industrial robot, and is wired through a movable part where operations such as bending, twisting, and swinging (hereinafter referred to as operations such as bending) are repeatedly performed. Note that the cable 1 is not limited thereto, and may be used, for example, as wiring for an automobile that is repeatedly swung (for example, wiring connecting a device provided on a vehicle body and a device provided on a wheel). Further, the cable 1 can also be used, for example, as medical wiring.

[0011] The cable 1 includes a central interposer 2, an inner layer 3, an inner tape member 4, a shield layer 6, an outer tape member 5, an outer layer 7, a pressing tape 8, and a sheath 9. Hereinafter, each part will be described in detail.

[0012] (Center Interposition 2) The cable 1 is repeatedly subjected to operations such as bending. Since the stress applied by operations such as bending increases at the center of the cable, it is desirable to arrange the signal line 3a and the power line 71 not at the center of the cable but to arrange the center interposition 2. In the present embodiment, as the center interposition 2, a linear body made of resin having a circular cross-section is used. As the resin used for the center interposition 2, for example, PVC (polyvinyl chloride) or PP (polypropylene) can be used. However, it is not limited thereto, and the center interposition 2 may be a tubular tube having a hollow portion along the longitudinal direction, or may be a fiber interposition using fibers such as spf (staple fiber) and nylon.

[0013] (Inner Layer 3) The inner layer 3 is configured by arranging a plurality of signal lines 3a along the circumferential direction of the cable. The signal line 3a corresponds to the first electric wire of the present invention. In the present embodiment, the plurality of signal lines 3a are helically twisted around the center interposition 2. FIG. 1 shows a case where 24 signal lines 3a are used, but the number of signal lines 3a used for the cable 1 is not limited thereto. However, the present invention is particularly effective in a multi-core cable 1 using 12 or more signal lines 3a in the inner layer 3.

[0014] In the present embodiment, each of the plurality of signal lines 3a is composed of a pair twist line 30 formed by twisting a pair of insulated electric wires 31. The insulated electric wire 31 has a conductor 31a composed of a collective twist line formed by collectively twisting a plurality of metal strands, and an insulator 31b covering the periphery of the conductor 31a. The metal strands constituting the conductor 31a are made of copper or a copper alloy, and may be plated with tin, silver, or the like on the surface thereof.

[0015] As the insulator 31b, in order to improve the transmission characteristics of high-speed signals, it is preferable to use one with a low dielectric constant (preferably, a dielectric constant of 3 or less). Specifically, as the insulator 31b, it is preferable to use a fluororesin such as ETFE (tetrafluoroethylene-ethylene copolymer), or one made of PP, PE (polyethylene), or the like. In particular, when a large number of signal lines 3a are used, in order to suppress the increase in the outer diameter of the cable 1, it is desirable to use a fluororesin such as ETFE that can be formed into a thin film as the insulator 31b.

[0016] Since the signal line 3a is formed by twisting a pair of insulated wires 31, it does not have a shield layer. In order to suppress crosstalk between the signal lines 3a, it is preferable to make the twist pitches of the signal lines 3a (twisted pair 30) adjacent to each other in the circumferential direction of the cable different. The twist pitch of the signal line 3a (twisted pair 30) is the interval along the longitudinal direction of the signal line 3a at a location where the circumferential position of an arbitrary insulated wire 31 (the position in the circumferential direction of the signal line 3a) is the same. In the present embodiment, by alternately arranging two types of signal lines 3a with different twist pitches, the twist pitches of the signal lines 3a adjacent to each other in the circumferential direction of the cable are made different.

[0017] The twist direction of the twisted pair 30 and the twist direction of the inner layer 3 are preferably different. This is because if the twist direction of the twisted pair 30 and the twist direction of the inner layer 3 are the same, the twist of the twisted pair 30 will be strengthened by the twisting of the inner layer 3, and when the cable 1 is repeatedly subjected to operations such as bending, the insulated wire 31 is likely to break. Note that the twist direction of the twisted pair 30 is the direction in which the insulated wire 31 rotates from one end to the other end as viewed from one end of the twisted pair 30. Also, the twist direction of the inner layer 3 is the direction in which the signal line 3a (twisted pair 30) rotates from one end to the other end as viewed from one end of the cable 1.

[0018] Incidentally, in the present embodiment, since the twisted pair 30 is used as the signal line 3a, the surface of the signal line 3a has many irregularities, and disconnection due to rubbing against surrounding members is relatively likely to occur. In particular, in the inner layer 3, a force that presses inward in the radial direction is likely to be applied from each member arranged radially outward of it. When an operation such as bending is repeatedly applied to the cable 1 in such a state, disconnection is more likely to occur in the signal line 3a. Therefore, in the present embodiment, by using members having cushioning properties as the shield layer 6 and the inner tape member 4 and the outer tape member 5, the pressing inward in the radial direction on the signal line 3a is alleviated, and the resistance to operations such as bending is improved. That is, according to the present embodiment, the force pushed inward in the cable radial direction can be alleviated, so that the signal line 3a can be arranged in the inner layer 3. Even if the inner layer 3 is the signal line 3a composed of the twisted pair 30, a decrease in resistance to operations such as bending is less likely to occur. Note that the signal line 3a (first electric wire) does not have to be the twisted pair 30 formed by twisting a pair of insulated electric wires 31, and may be, for example, an insulated electric wire or a coaxial cable.

[0019] (Shield layer 6) The shield layer 6 serves as a shield that covers the periphery of the signal line 3a in the inner layer 3 to suppress noise and as a cushioning layer for alleviating the pressing inward in the radial direction on the signal line 3a. More specifically, in the cable 1 according to the present embodiment, the shield layer 6 is provided between the inner layer 3 and the outer layer 7 and is composed of an intertwined braid formed by braiding metal strands and fiber strands. By configuring the shield layer 6 as an intertwined braid, cushioning properties can be imparted to the shield layer 6, the pressing inward in the radial direction on the signal line 3a can be alleviated, and the resistance to operations such as bending can be improved.

[0020] As the metal wire used for the shield layer 6, it is advisable to use one made of copper or a copper alloy, and its surface may be plated with tin, silver, or the like. Here, a tinned soft copper wire was used as the metal wire. As the fiber wire used for the shield layer 6, staple fiber (SF) yarn, nylon yarn, or the like can be used. The braiding angle of the interwoven braid constituting the shield layer 6 (the angle of the longitudinal direction of the metal wire or fiber wire with respect to the longitudinal direction of the cable) is preferably 40 degrees or more. Thereby, the holes between the metal wire and the fiber wire can be made smaller, and the cushioning property can be further enhanced. Incidentally, for example, in the case of a braided shield using only metal wires, if the braiding angle is 40 degrees or more, the shield layer 6 becomes very hard, and it becomes difficult to bend the cable 1. By making the shield layer 6 an interwoven braid as in this embodiment, even if the braiding angle is 40 degrees or more, it is possible to maintain sufficient flexibility, and while enhancing the cushioning property, the cable 1 can be easily bent.

[0021] (Inner tape member 4 and outer tape member 5) If the shield layer 6 made of an interwoven braid comes into direct contact with the inner layer 3 or the outer layer 7, when the cable 1 is repeatedly subjected to operations such as bending, there is a risk that the metal wires or fiber wires constituting the shield layer 6 may be disconnected due to friction. In order to suppress such a problem, in this embodiment, an inner tape member 4 is provided between the inner layer 3 and the shield layer 6, and an outer tape member 5 is provided between the shield layer 6 and the outer layer 7.

[0022] The inner tape member 4 is spirally wound around the inner layer 3 such that a part of it overlaps in the width direction. The outer tape member 5 is spirally wound around the shield layer 6 such that a part of it overlaps in the width direction. In order to relieve the radial inward pressing force on the signal line 3a, it is more desirable to use cushioning inner tape member 4 and outer tape member 5. Specifically, as the inner tape member 4 and the outer tape member 5, those made of non-woven fabric, paper, resin such as nylon or fluororesin, or foamed resin can be used. Among these, in particular, those made of non-woven fabric or foamed resin are more desirable for enhancing the cushioning property. As the foamed resin, for example, foamed polypropylene can be used. The thickness of the inner tape member 4 and the outer tape member 5 is preferably 50 μm or more and 100 μm or less. The materials of the inner layer tape member 4 and the outer layer tape member 5 are preferably the same. For example, when the inner layer tape member 4 is made of non-woven fabric, the outer layer tape member 5 is also made of non-woven fabric. Also, the thicknesses of the inner layer tape member 4 and the outer layer tape member 5 are preferably the same. Thereby, each tape of the inner layer tape member 4 and the outer layer tape member 5 can be made common, and the productivity of the cable 1 can be increased.

[0023] The winding direction of the inner tape member 4 is preferably the same as the twisting direction of the inner layer 3. Thereby, the twist of the inner layer 3 is less likely to loosen. Similarly, the winding direction of the outer tape member 5 is preferably the same as the twisting direction of the outer layer 7. Thereby, the winding of the outer tape member 5 is less likely to loosen. Note that the winding direction of the inner tape member 4 or the outer tape member 5 is the direction in which the inner tape member 4 or the outer tape member 5 rotates from one end to the other end as viewed from one end of the cable 1. Also, the twisting direction of the outer layer 7 is the direction in which the power line 71 rotates from one end to the other end as viewed from one end of the cable 1. Here, the twisting direction of the inner layer 3, the winding direction of the inner tape member 4, the winding direction of the outer tape member 5, and the twisting direction of the outer layer 7 are all set to the same direction.

[0024] (Outer layer 7) The outer layer 7 is provided to cover the periphery of the inner layer 3, and is configured by arranging a plurality of power lines 71 along the circumferential direction of the cable. In the present embodiment, the outer layer 7 is configured by twisting a plurality of power lines 71 for power supply around the outer tape member 5. Here, the case of using 36 power lines 71 is shown, but the number of power lines 71 is not limited to this.

[0025] The power line 71 has a conductor 71a made of a collective stranded wire formed by collectively stranding a plurality of metal strands, and an insulator 71b covering the periphery of the conductor 71a. The metal strands constituting the conductor 71a are made of copper or a copper alloy, and may be plated with tin, silver, etc. on their surfaces. As the insulator 71b of the power line 71, a polyolefin made of polypropylene, polyethylene, etc. is preferably used, and particularly preferably made of polypropylene. Thereby, compared with the case where the insulator 71b is made of a fluororesin such as ETFE (tetrafluoroethylene-ethylene copolymer), the flexibility of the power line 71 (the second electric wire) constituting the outer layer 7 can be improved, and the cable 1 can be easily bent. Also, the force pushing inward in the cable diameter direction from the outer layer 7 can be reduced. Therefore, the resistance when an operation such as bending is applied to the cable 1 can be improved.

[0026] The twisting direction of the outer layer 7 is preferably the same as the twisting direction of the inner layer 3. Thereby, the cable 1 can be easily bent, and the resistance to operations such as bending can also be improved. In the present embodiment, the case where the outer layer 7 is composed only of the power lines 71 is shown, but it is not limited thereto, and the outer layer 7 may include signal lines such as paired twisted wires.

[0027] (Pressing tape 8) The holding tape 8 serves to hold the twists of the power line 71 so that they do not unwind. As the holding tape 8, for example, a resin tape made of PE, PP, or the like can be used. The holding tape 8 is spirally wound around a plurality of power lines 71 such that a part in the width direction thereof overlaps. The winding direction of the holding tape 8 is preferably the same as the twisting direction of the outer layer 7. Note that the thickness of the holding tape 8 is preferably the same as the thicknesses of the inner layer tape member 4 and the outer layer tape member 5. Thereby, it becomes possible to make the tapes of the inner layer tape member 4, the outer layer tape member 5, and the holding tape 8 common, and the productivity of the cable 1 can be improved.

[0028] (Sheath 9) The sheath 9 is provided so as to cover the periphery of the holding tape 8. The sheath 9 is made of, for example, a resin composition mainly composed of PVC, silicone rubber, chlorinated polyethylene, or the like. Among these, in applications that require chemical resistance, a resin composition mainly composed of silicone rubber is preferably used. The resin composition may contain additives such as a crosslinking agent, a crosslinking catalyst, an antioxidant, a plasticizer, a lubricant, a filler, a flame retardant, a stabilizer, and a coloring agent. Further, a film for improving the slipperiness of the surface of the sheath 6 may be provided so as to cover the surface of the sheath 6. In particular, when the sheath 6 is made of a resin composition mainly composed of silicone rubber, a film for improving the slipperiness is preferably provided on the surface thereof. The film provided on the surface of the sheath 6 can be, for example, one formed by curing a liquid silicone rubber containing fine particles having an average particle diameter of 1 μm or more and 10 μm or less by an addition reaction. The fine particles are made of, for example, silicone rubber, silicone resin, or the like. The thickness of the film is, for example, 3 μm or more and 100 μm or less. The static friction coefficient of the surface of the film is 0.5 or less. Further, the sheath 6 is preferably separated from the integrated shield layer 5 by a minute gap or the like. Thereby, it is possible to suppress rubbing between the sheath 6 and the integrated shield layer 5 due to operations such as bending, and to prevent the sheath 6 from deteriorating.

[0029] (Actions and Effects of the Embodiment) As described above, in the cable 1 according to the present embodiment, a shield layer 6 made of an intertwined braid in which metal strands and fiber strands are braided is provided between the inner layer 3 and the outer layer 7. Since the shield layer 6 made of an intertwined braid has cushioning properties, it is possible to relieve the force pressing the inner layer 3 made of the first electric wire such as the twisted pair wire 30 inward in the cable diameter direction. As a result, even when an operation such as bending is repeatedly applied to the cable 1, it is possible to suppress disconnection of the insulated electric wire 31 constituting the twisted pair wire 30 or the like (that is, the first electric wire constituting the inner layer 3), and it is possible to improve the resistance to operations such as bending.

[0030] (Summary of the embodiment) Next, the technical idea grasped from the above-described embodiment will be described by referring to the reference numerals and the like in the embodiment. However, each reference numeral and the like in the following description are not limited to the members specifically shown in the embodiment for the components in the claims.

[0031] [1] An inner layer (3) in which a plurality of first electric wires (signal wires 3a) are arranged along the cable circumferential direction, a shield layer (6) covering the periphery of the inner layer (3) and made of an intertwined braid in which metal strands and fiber strands are braided, an outer layer (7) covering the periphery of the shield layer (6) and in which a plurality of second electric wires (power supply wires 71) are arranged along the cable circumferential direction, and a sheath (9) covering the periphery of the outer layer (7), the cable (1).

[0032] [2] An inner tape member (4) wound around the periphery of the inner layer (3) is provided between the inner layer (3) and the shield layer (6), and an outer tape member (5) wound around the periphery of the shield layer (6) is provided between the shield layer (6) and the outer layer (7). The cable (1) according to [1], wherein the inner tape member (4) and the outer tape member (5) are made of non-woven fabric or foamed resin.

[0033] [3] The winding direction of the inner tape member (4) is the same as the twisting direction of the inner layer (3), and the winding direction of the outer tape member (5) is the same as the twisting direction of the outer layer (7), for the cable (1) according to [2].

[0034] [4] The first electric wire (signal wire 3a) is composed of a pair of twisted wires (30) formed by twisting a pair of insulated electric wires (31), and the insulator (31b) of the pair of insulated electric wires (31) constituting the twisted wire (30) is made of a fluororesin, for the cable (1) according to [1].

[0035] [5] The second electric wire (power supply wire 71) is composed of a power supply wire (71) for power supply, and the insulator (71b) of the power supply wire (71) is made of a polyolefin, for the cable (1) according to [1].

[0036] (Supplementary Note) As described above, the embodiments of the present invention have been explained. However, the embodiments described above do not limit the invention according to the claims. Also, it should be noted that not all combinations of the features described in the embodiments are essential means for solving the problems of the invention. Further, the present invention can be appropriately modified and implemented without departing from its gist.

Explanation of Reference Numerals

[0037] 1... Cable 2... Central Interposition 3... Inner Layer 3a... Signal Wire (First Electric Wire) 30... Twisted Wire 31... Insulated Electric Wire 31a... Conductor 31b... Insulator 4... Inner Tape Member 5... Outer Tape Member 6... Shield Layer 7... Outer Layer 71... Power Supply Wire 71a... Conductor 71b... Insulator 8... Pressing Tape 9... Sheath

Claims

1. An inner layer in which a plurality of first electric wires are arranged along the circumferential direction of the cable, A shield layer that covers the periphery of the inner layer and is made of an intertwined braid in which metal strands and fiber strands are braided together, An outer layer that covers the periphery of the shield layer and in which a plurality of second electric wires are arranged along the circumferential direction of the cable, A sheath that covers the periphery of the outer layer, and the cable is provided with. Cable.

2. Between the inner layer and the shield layer, an inner tape member wound around the periphery of the inner layer is provided, and Between the shield layer and the outer layer, an outer tape member wound around the periphery of the shield layer is provided, The inner tape member and the outer tape member are made of non-woven fabric or foamed resin, The cable according to claim 1.

3. The winding direction of the inner layer tape member is the same as the twisting direction of the inner layer, The winding direction of the outer layer tape member is the same as the twisting direction of the outer layer, The cable according to claim 2.

4. The first electric wire is composed of a pair of twisted wires obtained by twisting a pair of insulated electric wires, The insulators of the pair of insulated electric wires constituting the pair of twisted wires are made of fluororesin, The cable according to claim 1.

5. The second electric wire is composed of a power supply line for power supply, The insulator of the power supply line is made of polyolefin, The cable according to claim 1.

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