Expandable cable

Abstract

This invention provides a retractable cable that minimizes excess cable length when wiring to movable parts. [Solution] The expandable cable 1 comprises an elastically deformable hollow insulator 2 having a continuous hollow section 2a along the longitudinal direction of the cable, and one or more linear bodies 3 that are spirally arranged along the longitudinal direction of the cable and fixed to the hollow insulator 2 so as to expand and contract together with the hollow insulator 2, and conduct electricity or light, so that when a tensile force is applied the entire cable stretches to 1.2 times or more, and when the tensile force is released it returns to its original length.

Description

Technical Field

[0001] The present invention relates to a telescopic cable.

Background Art

[0002] For example, in a cable wired through a movable part such as a joint of an industrial robot, repeated bending and twisting are applied to the cable by repeatedly operating the movable part. In such a cable wired through a movable part, it is common to wire with an extra length so that excessive tensile force does not act on the cable when the movable part is operated.

[0003] [[ID=十六]]In addition, as prior art document information related to the invention of this application, there is Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, industrial robots have been miniaturized, and accordingly, the wiring space for movable parts has become extremely narrow. Therefore, when wiring a cable through a movable part, if the extra length is increased, the extra length part will repeatedly interfere with surrounding members as the movable part operates, and the cable may be damaged due to this interference, or there may be no space for the cable to escape and kinks may occur.

[0006] Therefore, an object of the present invention is to provide a telescopic cable capable of reducing the extra length when wiring to a movable part. [[ID=4(4)]]

Means for Solving the Problems

[0007] The present invention aims to solve the above problems and provides an expandable cable comprising: an elastically deformable hollow insulator having a continuous hollow portion along the longitudinal direction of the cable; and one or more linear bodies that are spirally arranged along the longitudinal direction of the cable and fixed to the hollow insulator so as to expand and contract together with the hollow insulator, and which conduct electricity or light, wherein the entire cable expands to 1.2 times or more when a tensile force is applied, and returns to its original length when the tensile force is released. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a retractable cable that can reduce the excess length when wiring to a movable part. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows an expandable cable according to one embodiment of the present invention, where (a) is a diagram showing the appearance before and after expansion, and (b) is a cross-sectional view showing a section perpendicular to the longitudinal direction of the cable. [Figure 2] (a) and (b) are cross-sectional views showing a cross-section perpendicular to the longitudinal direction of a stretchable cable according to one modified example of the present invention. [Figure 3] (a) to (c) are cross-sectional views showing a cross-section perpendicular to the longitudinal direction of a stretchable cable according to one modified example of the present invention. [Modes for carrying out the invention]

[0010] [Embodiment] Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0011] Figure 1 shows an expandable cable according to this embodiment, where (a) is a view showing the appearance before and after expansion, and (b) is a cross-sectional view showing a section perpendicular to the longitudinal direction of the cable.

[0012] As shown in Figures 1(a) and 1(b), the expandable cable 1 comprises a hollow insulator 2 having a continuous hollow section 2a along the longitudinal direction of the cable, and one or more linear bodies 3 arranged spirally along the longitudinal direction of the cable. The expandable cable 1 is used, for example, as wiring material connected through the movable parts of an industrial robot.

[0013] The hollow insulator 2 has a circular cross-sectional shape perpendicular to the longitudinal direction of the cable. A hollow portion 2a with a circular cross-sectional shape perpendicular to the longitudinal direction of the cable is formed at the center of the hollow insulator 2, i.e., at the center of the expandable cable 1. The thickness of the hollow insulator 2 in the portion not in contact with the linear body 3 is approximately constant. In this embodiment, a hollow insulator 2 with an inner diameter of 2.7 mm and an outer diameter of 3.5 mm was used in an unloaded state without applying tensile force or the like.

[0014] The hollow insulator 2 is made of an elastically deformable material. More specifically, the hollow insulator 2 is preferably made of a material with an elongation of 300% to 500%. Furthermore, it is more desirable that the hollow insulator 2 can be stretched with a relatively small tensile force, and more preferably that it is made of a material with a stress of 3 MPa or less when stretched to 100%.

[0015] To satisfy the above-mentioned characteristics, the hollow insulator 2 is preferably composed of a thermoplastic material containing a rubber component or a material obtained by crosslinking such a material. Suitable rubber components for the hollow insulator 2 include ethylene propylene rubber, ethylene-1-octene copolymer elastomer (EOR), ethylene-1-butene copolymer elastomer (EBR), styrene-based elastomer, natural rubber, chloroprene rubber, butyl rubber, urethane rubber, silicone rubber, fluororubber, etc. Furthermore, the hollow insulator 2 is preferably composed of 50 mass% to 100 mass% of the above-mentioned rubber component.

[0016] Other materials used in the hollow insulator 2 besides the rubber component include, for example, olefin resins such as polyethylene and polypropylene, engineering plastics such as polyphenylene ether (PPE), and polyvinyl chloride (PVC) to prevent tackiness. Other additives used in the hollow insulator 2 may include plasticizers, antioxidants, flame retardants, colorants, inorganic fillers, and processing aids. When crosslinking the hollow insulator 2, methods such as crosslinking by electron beam irradiation, or crosslinking using chemical crosslinking agents or silane coupling agents can be used.

[0017] The linear body 3 conducts electricity or light. In other words, the linear body 3 transmits electrical signals or optical signals. Here, as the linear body 3, an insulated wire 33 is used, which has a conductor 31 made of a stranded conductor formed by twisting together multiple metal strands, and an insulator 32 covering the conductor 31. However, the linear body 3 is not limited to an insulated wire 33; for example, it may consist only of the conductor 31, or it may be made of optical fiber. Also, a single-wire conductor may be used as the conductor 31. In this embodiment, a conductor 31 made of a stranded conductor formed by twisting together seven metal strands and having an outer diameter of 0.3 mm was used. As the insulator 32, for example, materials such as ethylene propylene rubber, ethylene-1-octene copolymer elastomer (EOR), ethylene-1-butene copolymer elastomer (EBR), styrene-based elastomer, natural rubber, chloroprene rubber, butyl rubber, urethane rubber, silicone rubber, fluororubber, etc. can be used. In this embodiment, an insulator 32 made of styrene elastomer with an outer diameter of 0.8 mm was used.

[0018] The linear body 3 is arranged spirally along the longitudinal direction of the cable and is fixed to the hollow insulator 2 so as to expand and contract together with the hollow insulator 2. Furthermore, a portion of the linear body 3 is positioned so as to be embedded within the hollow insulator 2, and the linear body 3 and the hollow insulator 2 are in surface contact, and the two are bonded together at this contact surface, becoming one unit. In this embodiment, in a cross-sectional view perpendicular to the longitudinal direction of the cable, a portion of the linear body 3 is exposed within the hollow portion 2a, and the other portion is covered by the hollow insulator 2.

[0019] Also, in the telescopic cable 1, in the no-load state where no tensile force or the like is applied, the linear bodies 3 adjacent to each other in the cable circumferential direction and the longitudinal direction are separated from each other, and a hollow insulator 2 exists between the linear bodies 3 adjacent to each other in the cable circumferential direction and the longitudinal direction. When a tensile force is applied to the telescopic cable 1, the hollow insulator 2 between the linear bodies 3 extends, making the entire telescopic cable 1 more likely to extend.

[0020] When manufacturing the telescopic cable 1, one or more dummy wires are used, and the linear bodies 3 are spirally wound around the dummy wires, or after twisting the linear bodies 3 and the dummy wires together, the hollow insulator 2 is formed around them by extrusion molding. Due to the heat when forming this hollow insulator 2, the hollow insulator 2 and the linear bodies 3 are melted and integrated and fixed to each other. Then, if the dummy wires are removed, the telescopic cable 1 can be obtained.

[0021] Now, in the telescopic cable 1 according to this embodiment, when a tensile force is applied, the entire cable extends 1.2 times or more, preferably 2 times or more, more preferably 3 times or more, and has a restoring force to return to the original length when the tensile force is released. That is, as shown in Fig. 1(a), if the distance between any two points A and B in the longitudinal direction of the telescopic cable 1 before stretching is L0, when a tensile force is applied to the telescopic cable 1, the distance L1 between points A and B becomes 1.2 times or more, preferably 2 times or more, more preferably 3 times or more of L0, and when the tensile force is released, the distance between A and B returns to L0. Also, in the case of the telescopic cable 1 according to this embodiment, when a tensile force is applied and then released, not only does it return to the original length, but it is also easy to restore to the original shape (basically, a straight line shape), so the telescopic cable 1 has the characteristic of being less likely to become entangled.

[0022] As a result, for example, when the telescopic cable 1 is wired through a movable part such as a joint of an industrial robot, the telescopic cable 1 can expand and contract according to the movement of the movable part, eliminating the need for wiring with extra length. Consequently, even when the wiring space for laying the telescopic cable 1 is narrow, the telescopic cable 1 is less likely to interfere with surrounding members, making it possible to suppress damage to the telescopic cable 1 and the occurrence of kinks caused by such interference. That is, by using the telescopic cable 1 as a wiring material for the movable part, the durability (i.e., bending resistance and twisting resistance) against operations such as bending and twisting of the movable part can be improved. Further, in the telescopic cable 1, since the highly rigid linear body 3 is arranged in a spiral shape, this linear body 3 maintains the shape of the entire telescopic cable 1, making the telescopic cable 1 less likely to buckle.

[0023] The elongation of the telescopic cable 1 can be controlled by the material used for the hollow insulator 2, the spiral pitch and winding diameter when arranging the linear body 3 in a spiral shape, etc. Note that the spiral pitch of the linear body 3 is the interval along the cable longitudinal direction at the same circumferential position on the linear body 3 when arranging the linear body 3 in a spiral shape. Also, the winding diameter of the linear body 3 is the diameter of the circle drawn by the center of the linearly arranged body 3 when viewed from the cable longitudinal direction. In the present embodiment, the spiral pitch was set to 3.0 mm and the winding diameter was set to 1.1 mm.

[0024] Here, the behavior of the telescopic cable 1 when it extends will be examined in detail. When a tensile force is applied to the telescopic cable 1 to stretch it, as the hollow insulator 2 is stretched, the outer diameter of the hollow insulator 2 becomes smaller compared to before stretching. Also, as the telescopic cable 1 extends, the linear body 3 is also stretched, increasing the spiral pitch of the linear body 3 and decreasing the winding diameter. At this time, since the rigidity of the linear body 3 is higher than that of the hollow insulator 2, the linear body 3 protrudes from the outer surface of the stretched hollow insulator 2. As a result, in the state where the tensile force is applied, a spiral convex portion 4 appears on the outer peripheral surface of the telescopic cable 1.

[0025] When connecting the expandable cable 1 to a circuit board or connector, a terminal process is performed at the end of the expandable cable 1 to expose the linear body 3 from the hollow insulator 2. In this case, it is preferable to peel and separate the linear body 3 from the hollow insulator 2. In this embodiment, one linear body 3 is used, but especially when multiple linear bodies 3 are used, the multiple linear bodies 3 do not fall apart during the terminal processing work and remain fixed to the hollow insulator 2, resulting in good workability during terminal processing.

[0026] When tensile force is continuously applied to the stretchable cable 1, and the cable 1 stretches beyond its limit, the hollow insulator 2 will break first. Subsequently, when the linear body 3 is stretched to a nearly straight state and further tensile force is applied, the linear body 3 will break. However, by adjusting the spiral pitch and winding diameter of the linear body 3, the length of the linear body 3 can be shortened to be shorter than the elongation required for the hollow insulator 2 to break, thereby changing the breaking mode so that the linear body 3 breaks first, followed by the hollow insulator 2. In other words, the breaking mode can be controlled by the elongation of the material used for the hollow insulator 2 and the spiral pitch and winding diameter of the linear body 3.

[0027] (modified version) In this embodiment, only one linear body 3 is used, but this is not limited to this. For example, two linear bodies 3 may be used, as in the expandable cable 1a shown in Figure 2(a), or four linear bodies 3 may be used, as in the expandable cable 1b shown in Figure 2(b). When using multiple linear bodies 3 as in expandable cables 1a and 1b, the linear bodies 3 should be arranged so that they are equally spaced in the circumferential direction in a cross-sectional view perpendicular to the longitudinal direction of the cable. For example, in expandable cable 1a using two linear bodies 3, linear bodies 3 with an outer diameter of 0.5 mm can be used, and hollow insulators 2 with an outer diameter of 3 mm can be used.

[0028] Furthermore, the linear elements 3 used do not all need to have the same outer diameter; linear elements 3 with different outer diameters may be used. In addition, for example, the electric wire used for the linear elements 3 does not have to be an insulated electric wire 33; for example, a coaxial cable may be included. Also, the linear elements 3 may include both electric wires and optical fibers.

[0029] Furthermore, although this embodiment describes a case where a part of the linear body 3 is exposed within the hollow portion 2a, it is not limited to this. For example, as shown in the stretchable cable 1c in Figure 3(a), the entire linear body 3 may be covered by the hollow insulator 2, or as shown in the stretchable cable 1d in Figure 3(b), a part of the linear body 3 may be exposed on the outer circumference side of the hollow insulator 2, with the other part covered by the hollow insulator 2. In the stretchable cables 1c and 1d, since there are no irregularities caused by the linear body 3 in the hollow portion 2a, it becomes possible to apply a coating to the inner surface of the hollow insulator 2. Therefore, for example, it becomes possible to apply a coating to the inner surface of the hollow insulator 2 to improve its slipperiness and use it for applications such as catheters. On the other hand, in the stretchable cables 1 and 1c shown in Figures 1 and 3(a), the linear body 3 does not protrude from the outer circumference side of the hollow insulator 2, resulting in a good appearance, and the linear body 3 is less likely to be damaged because it is protected from trauma by the hollow insulator 2.

[0030] Furthermore, as shown in Figure 3(c) for the expandable cable 1e, the linear body 3 may have a portion exposed within the hollow portion 2a in a cross-sectional view perpendicular to the longitudinal direction of the cable, while another portion is exposed on the outer circumference side of the hollow insulator 2, with the remaining portion covered by the hollow insulator 2. In this example, since the linear body 3 is provided so as to penetrate the hollow insulator 2 in the radial direction of the cable, the hollow insulator 2 is provided in sections between adjacent linear bodies 3 in the circumferential direction, and is provided in an arc shape so as to connect adjacent linear bodies 3 in the circumferential direction. The expandable cable 1e makes it possible to reduce the outer diameter of the expandable cable 1, making it possible to accommodate narrower wiring spaces. In addition, it becomes easier to separate (peel off) the linear body 3 from the hollow insulator 2, improving workability during terminal processing. Furthermore, it is possible to reduce the amount of resin used in the hollow insulator 2, thus reducing costs.

[0031] (Operation and Effects of the Embodiment) As described above, the expandable cable 1 according to this embodiment comprises an elastically deformable hollow insulator 2 having a continuous hollow portion 2a along the longitudinal direction of the cable, and one or more linear bodies 3 that are spirally arranged along the longitudinal direction of the cable and fixed to the hollow insulator 2 so as to expand and contract together with the hollow insulator 2, and conduct electricity or light, so that when a tensile force is applied the entire cable stretches to 1.2 times or more, and when the tensile force is released it returns to its original length.

[0032] This makes it possible to reduce (or eliminate) excess cable length and slack when wiring to moving parts of, for example, industrial robots, thereby suppressing damage caused by repeated interference of the excess cable with surrounding materials and preventing kinking caused by the presence of excess cable. As a result, it is possible to realize a highly durable expandable cable 1 that can withstand the movement of the moving parts (i.e., movements such as bending and twisting) when wired to those parts. In addition, since it becomes unnecessary to design wiring that takes excess cable length into consideration, the wiring design of equipment becomes easier when using the expandable cable 1.

[0033] (Applications of stretchable cable 1) In the above embodiment, the case in which the expandable cable 1 is used as wiring material routed through the movable parts of an industrial robot was described. However, the use of the expandable cable 1 is not limited to this, and it can be used as wiring material routed through movable parts in various devices such as industrial, medical, and home appliance equipment.

[0034] Furthermore, the expandable cable 1 can also be applied to applications where the cable itself requires expandability. For example, the expandable cable 1 can be used as wiring for wearable products such as eyeglasses, wristbands, earphones, and clothing, or as expandable wiring for platform doors and elevators. In addition, it can be used as a replacement for telephone coiled cords. Coiled cords have problems such as tangling and pinching when stretched and then retracted, but these problems can be solved by applying the expandable cable 1.

[0035] Furthermore, the expandable cable 1 can also be applied to cables that are not originally intended to be expandable. In this case, the expandability of the expandable cable 1 can absorb differences in wiring length to a certain extent. Therefore, an expandable cable assembly equipped with terminal components such as connectors at the ends of the expandable cable 1 is highly versatile and can accommodate various wiring lengths, eliminating the need to prepare many different types of cables with varying lengths.

[0036] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals and other symbols in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0037] [1] An expandable cable (1) comprising: an elastically deformable hollow insulator (2) having a continuous hollow portion (2a) along the longitudinal direction of the cable; and one or more linear bodies (3) that are spirally arranged along the longitudinal direction of the cable and fixed to the hollow insulator (2) so as to expand and contract together with the hollow insulator (2), and which conduct electricity or light, wherein the entire cable expands to 1.2 times or more when a tensile force is applied, and returns to its original length when the tensile force is released.

[0038] [2] The stretchable cable (1) described in [1], wherein the entire cable stretches to three times or more its length when a tensile force is applied, and returns to its original length when the tensile force is released.

[0039] [3] The stretchable cable (1) according to [1] or [2], wherein the elongation of the hollow insulator (2) is 300% or more.

[0040] [4] The hollow insulator (2) is a stretchable cable (1) as described in any one of items [1] to [3], wherein the stress when stretched to 100% is 3 MPa or less.

[0041] [5] An expandable cable (1) according to any one of items [1] to [4], wherein adjacent linear bodies (3) in the circumferential and longitudinal directions of the cable are spaced apart from each other.

[0042] [6] The stretchable cable (1) according to any one of [1] to [5], wherein, in a cross-sectional view perpendicular to the longitudinal direction of the cable, a portion of the linear body (3) is exposed within the hollow portion (2a) and the other portion is covered by the hollow insulator (2).

[0043] [7] The stretchable cable (1c) according to any one of [1] to [5], wherein the linear body (3) is entirely covered by the hollow insulator (2) in a cross-sectional view perpendicular to the longitudinal direction of the cable.

[0044] [8] The stretchable cable (1d) according to any one of [1] to [5], wherein, in a cross-sectional view perpendicular to the longitudinal direction of the cable, a portion of the linear body (3) is exposed to the outer circumference of the hollow insulator (2), and the other portion is covered by the hollow insulator (2).

[0045] [9] In a cross-sectional view perpendicular to the longitudinal direction of the cable, the linear body (3) has a portion exposed within the hollow portion (2a), another portion exposed on the outer circumference side of the hollow insulator (2), and the remaining portion covered by the hollow insulator (2), any of [1] to [5] The expandable cable (1e) as described in item 1.

[0046]

[10] A stretchable cable (1) as described in any one of [1] to [9], used as wiring material connected through the movable parts of an industrial robot.

[0047] Although embodiments of the present invention have been described above, the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. In addition, the present invention can be implemented with appropriate modifications without departing from its spirit. [Explanation of Symbols]

[0048] 1… Extendable cable 2…Hollow insulator 2a...Hollow part 3... Linear body 4…Convex part 31... Conductor 32...Insulator 33...Insulated wire

Claims

1. An elastically deformable hollow insulator having a continuous hollow section along the longitudinal direction of the cable, It comprises one or more linear bodies that are arranged spirally along the longitudinal direction of the cable and fixed to the hollow insulator so as to expand and contract together with the hollow insulator, and that conduct electricity or light, The linear body is fixed to the hollow insulator along the entire length of the cable. When tensile force is applied, the entire cable stretches to 1.2 times or more its original length, and when the tensile force is released, it returns to its original length. Expandable cable.

2. The linear body is fused and fixed to the hollow insulator by the heat generated when forming the hollow insulator. The expandable cable according to claim 1.

3. The aforementioned hollow insulator is formed by extrusion molding. The expandable cable according to claim 2.

4. When tensile force is applied, a spiral-shaped protrusion appears on the outer surface of the cable. The expandable cable according to any one of claims 1 to 3.

5. The linear bodies adjacent to each other in the circumferential and longitudinal directions of the cable are spaced apart. The expandable cable according to any one of claims 1 to 4.

6. In a cross-sectional view perpendicular to the longitudinal direction of the cable, a portion of the linear body is exposed within the hollow portion, while the other portion is covered by the hollow insulator. The expandable cable according to any one of claims 1 to 5.

7. In a cross-sectional view perpendicular to the longitudinal direction of the cable, the linear body is entirely covered by the hollow insulator. The expandable cable according to any one of claims 1 to 5.

8. In a cross-sectional view perpendicular to the longitudinal direction of the cable, a portion of the linear body is exposed to the outer periphery of the hollow insulator, while the remaining portion is covered by the hollow insulator. The expandable cable according to any one of claims 1 to 3.

9. In a cross-sectional view perpendicular to the longitudinal direction of the cable, a portion of the linear body is exposed within the hollow portion, another portion is exposed to the outer periphery of the hollow insulator, and the remaining portion is covered by the hollow insulator. The expandable cable according to any one of claims 1 to 3.

10. Used as wiring material for connections made through the movable parts of industrial robots. The stretchable cable according to any one of claims 1 to 9.

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