cable

Abstract

To provide a cable which enables smooth bending and has improved durability. The cable is formed by covering a conductor section, in which conductors are arranged in a spiral shape in the longitudinal direction, with an insulating coating material having insulating properties. The cable is composed of a conductor section in which a core wire is formed by twisting together multiple bare wires and multiple core wires are arranged closely together in a circular ring shape, and a string body made of multiple threads of a fiber material, and the string body is compressed and stored in a substantially linear shape within a central space formed by the circular core wire of the conductor section, and the string body is press-fitted into the central space.

Description

[Technical field]

[0001] The present invention relates to a cable composed of multiple conductors, and more particularly to a cable with improved durability. [Background technology]

[0002] In recent years, the demand for cables with high wiring workability has been increasing due to the development of the robotics industry. Such cables are used as large conductor size, large current power lines for applications such as sliding parts of transport robots and welding power cables, and are often used under repeated bending motions. Therefore, in addition to being flexible, they are required to have high durability against repeated bending motions over a long period of time.

[0003] For these reasons, in order to increase flexibility and durability, many conventional cables are constructed with concentrically twisted conductors covered with PVC (polyvinyl chloride) insulation or a PVC sheath so that the cable cross-section is circular.

[0004] For example, a conventional cable is known in which a conductor is made of multiple child twisted conductors twisted together in a single layer structure, and in the cross-sectional configuration of the conductor cut in a direction perpendicular to the longitudinal direction, a gap is formed in the center of the multiple child twisted conductors, and complementary members are twisted between each of the child twisted conductors (see Patent Document 1).

[0005] Furthermore, a known example of a conventional cable is a cable in which multiple insulated cores, each having a conductor covered with rubber or vinyl, are twisted together with intervening jute inserted into the gaps between them, and a rubber or plastic sheath is applied around the outer periphery (see Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-119857 A [Patent Document 2] Public Disclosure No. 56-76219 Summary of the Invention [Problem to be solved by the invention]

[0007] For example, in a cable in which a gap is formed in the center of multiple child stranded conductors as in Patent Document 1, when the cable is operated, the overall shape of the cable is easily crushed from the gap in the center, which easily induces damage to the child stranded conductors, resulting in low durability. Also, in a cable composed of multiple individually covered insulated cores as in Patent Document 2, there is a problem that it is difficult to obtain a sufficiently large current with the generated current indicated by the total value of these multiple independent insulated cores. Also, in such a cable composed of multiple insulated cores, there are problems in that the outer diameter becomes large and the manufacturing costs increase by dividing the internal conductor and insulating and taping the divided conductors.

[0008] Furthermore, in the case of cables using PVC insulation or a PVC sheath, such as cables with a rubber or plastic sheath as in Patent Document 2, the rubber has low elasticity, so that stress generated when the cable is twisted or bent occurs locally, making the cable prone to damage and low durability.

[0009] That is, when conventional cables are used as high-current power lines, they require thick conductors. However, when the cable is bent or twisted, these thick conductors move inside the insulation, causing the conductors to interfere with each other and become damaged, resulting in reduced durability.

[0010] The present invention has been made to solve the above problems, and has an object to provide a cable that allows smooth bending motion while having improved durability. [Means for solving the problem]

[0011] As a result of extensive research, the inventors discovered a cable with improved durability through an improved layout structure, which led to the completion of the present invention.

[0012] Thus, the cable disclosed in the present application is a cable formed by covering a conductor portion, in which the conductor is arranged in a spiral shape in the longitudinal direction, with an insulating coating material having insulating properties, and is equipped with a conductor portion formed by twisting together a plurality of bare wires to form a core wire, and a reinforcing portion composed of a string body made of a plurality of threads of a fiber material, the string body being compressed and stored in a substantially linear shape within a central space formed by the annular core wire of the conductor portion, and the string body being press-fitted into the central space.

[0013] In this way, the cable disclosed in the present application is a cable in which a conductor portion in which conductors are arranged in a spiral shape in the longitudinal direction is covered with an insulating covering material having insulating properties, the cable comprising: a conductor portion in which a core wire is formed by twisting together a plurality of bare wires, and a plurality of the core wires are arranged closely together in an annular shape; and a reinforcing portion composed of a string body made of a plurality of threads of a fiber material, the string body being compressed and stored in a substantially linear shape in a central space formed by the annular core wire of the conductor portion, and since the string body is pressed into the central space, the string body is pressed into the central portion of the cable, and the amount of the string body in the central portion is packed in more than the theoretically calculated cross-sectional area, reducing the contact pressure between the bare wires, and the string body having cushioning properties in the central portion supports the cable with a force directed radially from the central portion of the cable toward the outer periphery, thereby significantly improving cable durability, for example, during twisting operations performed by a welding robot or the like, thereby making it possible to suppress the occurrence of cable breakage. In addition, because the child strands are made of bare wires that are not isolated from each other by insulating materials or tape, high processability is achieved, allowing the terminals to be easily joined. This makes handling easier and reduces manufacturing costs compared to conventional technology, which requires stripping the coated wires of multiple child strands and joining them at the terminals.

[0014] In the cable disclosed in the present application, the cross-sectional area of ​​the cord body in its natural placement is formed to be larger than the cross-sectional area of ​​the central space, as necessary. In this way, the cross-sectional area of ​​the cord body in its natural placement is formed to be larger than the cross-sectional area of ​​the central space, so that the cord body as an intermediate is pressed into the central portion in a highly compressed state, and thus the cable is formed while the cord body maintains a high flexibility, improving the cushioning properties of the cord body and further improving the durability of the cable.

[0015] In the cable disclosed in the present application, the cord is made of synthetic fiber as necessary. Since the cord is made of synthetic fiber, the cord made of highly flexible synthetic fiber is pressed into the center of the cable, and the amount of the cord in the center can be more than the theoretical calculation cross-sectional area, which reduces the contact pressure between the bare wires, and the cord made of cushioning synthetic fiber in the center supports the cable with a force radially from the center of the cable toward the outer periphery, which reliably maintains the soft state of the cord and further improves the durability of the cable.

[0016] In the cable disclosed in the present application, the reinforcing part stores the cord in the central space at a period shorter than the spiral period of the conductor part as necessary. In this way, since the reinforcing part stores the cord in the central space at a period shorter than the spiral period of the conductor part, the cord as an intermediate made of synthetic fiber is pressed into the central part in a state close to straight insertion in which the cord is kept highly linear, and the cable is formed while the cord is kept soft, so that the cushioning property of the cord can be further improved and the durability of the cable can be further improved.

[0017] In the cable disclosed in the present application, the core wires are in close linear contact with each other at multiple points as necessary. Since the core wires are in close linear contact with each other at multiple points in this manner, the contact area between the bare wires is wider, which reduces the generation of heat and voltage drop in the unlikely event of cable damage, thereby further improving safety.

[0018] In the cable disclosed in the present application, the diameter of the conductor portion is 3 to 6 times the diameter of the core wire, as necessary. Since the diameter of the conductor portion is 3 to 6 times the diameter of the core wire, the ratio of the diameter of the core wire to the diameter of the conductor portion is optimized, which reduces stress due to twisting and interference between bare wires, and the durability is optimally increased due to the optimal filling degree of the core wire.

[0019] In the cable disclosed in the present application, the diameter of the core wire is 8 to 60 times the diameter of the bare wire, as necessary. Since the diameter of the core wire is 8 to 60 times the diameter of the bare wire, the ratio of the diameter of the core wire to the conductor diameter of the bare wire is optimized, which reduces the generation of stress caused by twisting, and the durability is optimally increased due to the optimal filling degree of the bare wire.

[0020] The cable disclosed in the present application has a gap formed in the region formed between adjacent conductor portions and the insulating coating material as necessary. Since a gap is thus formed in the region formed between adjacent conductor portions and the insulating coating material, when the cable is used with repetitive motions such as twisting motions in a welding robot, the gap acts as a cushion, significantly improving cable durability and making it possible to suppress breakage, and since cutting of members in the region is not required, processability is improved and manufacturing costs can be suppressed.

[0021] In the cable disclosed in the present application, the conductor portion is configured from 6 to 15 of the core wires as necessary. Since the conductor portion is configured from 6 to 15 of the core wires in this way, the ratio of the core wires to the conductor portion is optimized, which reduces stress due to twisting and interference between bare wires, and the durability is optimally increased due to the optimal packing degree of the core wires. [Brief description of the drawings]

[0022] [Figure 1] 1 is a configuration diagram of a cable according to a first embodiment of the present invention; [Diagram 2] FIG. 2 is an explanatory diagram illustrating the relationship between adjacent core wires of the cable according to the first embodiment of the present invention. [Diagram 3] FIG. 2 is an explanatory diagram for explaining the diameter of a conductor part and the diameter of a core wire of a cable according to a first embodiment of the present invention. [Figure 4] FIG. 2 is an explanatory diagram for explaining the diameter of a core wire and the diameter of a bare wire of a cable according to a first embodiment of the present invention. [Diagram 5] FIG. 1 is an explanatory diagram illustrating a configuration of a cable according to a first embodiment of the present invention. [Figure 6] FIG. 2 is an explanatory diagram for explaining press-fitting of a cord of a cable according to the first embodiment of the present invention. [Figure 7] FIG. 6 is a configuration diagram of a cable according to a second embodiment of the present invention. [Figure 8] 4 shows the results of calculation of the cable outer diameter according to the number of core wires of the cable according to Example 1 of the present invention. [Figure 9] 6 shows the measurement results of a twisting test on a cable according to Example 2 of the present invention. [Figure 10] 1 shows the results of the appearance (conductor appearance) of each cable in a twisting test of the cable according to Example 2 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] (First embodiment) As shown in FIG. 1, the cable according to the first embodiment is a cable formed by covering a conductor section 1, in which the conductor is arranged in a spiral shape in the longitudinal direction, with an insulating covering material 3 having insulating properties. The cable is composed of the conductor section 1, in which a core wire 12 is formed by twisting together a number of bare wires 11 and a number of core wires 12 are arranged closely together in a circular ring shape, and a string body 21 made of a number of threads 21a made of a fiber material, and the string body 21 is compressed and stored in a substantially linear shape in a central space formed by the circular ring-shaped core wire 12 of the conductor section 1, and the string body 21 is press-fitted into this central space.

[0024] The conductor portion 1 is formed by arranging the core wire 12 in a spiral shape. That is, the conductor portion 1 is formed by twisting the core wire 12 along the longitudinal direction.

[0025] This core wire 12 is formed by twisting a plurality of these bare wires 11 together. That is, it can be formed as a composite twisted conductor. The twisting method is not particularly limited, and may be rope twisting or bunch twisting. In addition, the correlation between the conductor twisting direction (conductor parent twisting direction) and the bunching direction is not particularly limited, but it is preferable that they are in the same direction, and higher durability can be exhibited than when the twisting directions are in different directions.

[0026] The outer diameter of the conductor 1 is preferably 0.85 times or more the theoretically calculated value (i.e., not less than "theoretical outer diameter value - 15%), and can be, for example, about 0.85 to 0.98 times the theoretically calculated value. When the bare wires 11 of the conductor 1 partially come into contact with each other and are flattened, the outer diameter of the conductor 1 becomes smaller. If the outer diameter of the conductor 1 becomes too small below 0.85 times the theoretically calculated value, the contact pressure becomes large and durability decreases.

[0027] The conductor portion 1 is not particularly limited as long as it has a structure in which the core wires 12 are arranged concentrically, but preferably has a structure in which the core wires 12 are twisted together in a single layer.

[0028] The material of this bare wire 11 is not particularly limited, but for example, a copper wire can be used. Also, from the viewpoint of excellent durability, a metal-plated copper wire can be used. Also, a soft copper wire, which is a soft copper wire for electrical use and has a smooth surface, can be used, and in this case, higher flexibility and conductivity can be obtained compared to a hard copper wire. From this viewpoint, for example, a tin-plated soft copper wire can be used as the conductor constituting this bare wire 11, and the corrosion resistance of the conductor surface can be improved.

[0029] The conductor portion 1 is formed by arranging a plurality of the core wires 12 in close contact with each other in a circular ring shape. Due to the shape of the plurality of closely-spaced core wires 12, adjacent core wires 12 have electrical contact with each other, and the core wires 12 arranged on this ring function as a bundle of conductors, making it easier to obtain a large current and improving electrical safety. In addition, since adjacent core wires 12 have electrical contact with each other, it is easy to comply with safety standards for equipment.

[0030] More preferably, as shown in Fig. 2, adjacent core wires 12 are in contact with each other at multiple points, points a and b, and are in close contact along the line shape of straight line L formed by the multiple points a and b. Similarly, as shown in Fig. 2, adjacent core wires 12 are in contact with each other at multiple points, points c and d, and are in close contact along the line shape of straight line M formed by the multiple points c and d. That is, from a macroscopic point of view, in appearance, adjacent core wires 12 are in so-called surface contact with each other.

[0031] In this way, because the core wires 12 are in close linear contact at multiple points, the contact area between the core wires 12 is wider, which reduces the generation of heat and voltage drop in the unlikely event of cable damage, further improving safety. Also, because the core wires 12 are not isolated by other insulating members, taping, etc., durability is improved, workability is good, and electrical safety can also be improved.

[0032] As shown in FIG. 3, the correlation between the diameter D of the conductor portion 1 and the diameter d of the core wire 12 is not particularly limited, but preferably the diameter D of the conductor portion 1 is 3 to 6 times (including both end values ​​3 and 6; the same applies below) the diameter d of the core wire 12.

[0033] That is, the diameter ratio D / d is preferably 3-6, and more preferably, the ratio D / d is 3.5-5.

[0034] If the diameter ratio D / d is smaller than 3, interference between the core wires 12 may become large. On the other hand, if the diameter ratio D / d is larger than 6, the outer diameter of the stranded core wires 12 becomes large, which is likely to cause an increase in manufacturing cost and an increase in the outer diameter.

[0035] Furthermore, if the core wires 12 are twisted together in two layers, the first and second layers of the core wires 12 will interfere with each other, decreasing durability. For this reason, the core wire 12 preferably has a single layer structure and a diameter ratio D / d of 3 to 6.

[0036] In this way, since the diameter of the conductor portion 1 is 3 to 6 times the diameter of the core wire 12, the ratio of the diameter of the core wire 12 to the diameter of the conductor portion 1 is optimized, thereby reducing stress due to twisting action and interference between the bare wires 11, and the optimal filling degree of the core wire 12 optimally enhances durability.

[0037] 4, the correlation between the diameter d of the core wire 12 and the diameter d1 of the bare wire 11 constituting the core wire 12 is not particularly limited, but preferably the diameter d of the core wire 12 is 8 to 60 times the diameter d1 of the bare wire 11. In other words, it is preferable that the diameter ratio d / d1 is 8 to 60 (including both the extreme values ​​8 and 60; the same applies below).

[0038] For example, based on calculation results under conditions of a cable with a total cross-sectional area of ​​8 to 55 sq., 6 to 15 core wires (12), and a wire (bare wire 11) diameter of 0.08 to 0.12 mm, the diameter ratio d / d1 is within the range of 8 to 60 whether the calculation is based on bunched twist or on 7-twist.

[0039] For example, when seven strands of this bare wire (11) are twisted, the diameter ratio d / d1 is calculated to be 9 under the conditions of a total cable cross-sectional area of ​​8 sq., 15 core wires (12), and a diameter of the bare wire (11) of 0.12 mm. Similarly, when seven strands are twisted, the diameter ratio d / d1 is calculated to be 56 under the conditions of a total cable cross-sectional area of ​​55 sq., 6 core wires (12), and a diameter of the bare wire (11) of 0.08 mm.

[0040] For example, when these bare wires (bare wires 11) are bundle-twisted, the diameter ratio d / d1 is calculated to be 8 under the conditions of a total cable cross-sectional area of ​​8 sq., 15 core wires (12), and a bare wire (11) diameter of 0.12 mm. Similarly, in the case of bundle-twisted cable, the diameter ratio d / d1 is calculated to be 49 under the conditions of a total cable cross-sectional area of ​​55 sq., 6 core wires (12), and a bare wire (11) diameter of 0.08 mm.

[0041] In this way, since the diameter of the core wire 12 is 8 to 60 times the diameter of the bare wire 11, the ratio of the diameter of the core wire 12 to the conductor diameter of the bare wire 11 is optimized, thereby reducing the generation of stress caused by the twisting action, and the optimal filling degree of the bare wire 11 optimally enhances durability.

[0042] Furthermore, the number of core wires 12 is not particularly limited, but is preferably 6 to 15 (including both end values ​​6 and 15; the same applies below), and more preferably 8 to 12, and can be, for example, 10, which can improve twisting durability.

[0043] The reason for this is that if the number of core wires 12 is less than 6, durability decreases, and if the number is more than 15, the outer diameter increases and manufacturing costs increase. If the core wires 12 are twisted in two layers to avoid this increase in the outer diameter, the core wires 12 in the first and second layers constituting the two-layer twist interfere with each other, decreasing durability.

[0044] In this way, by making the conductor portion 1 out of 6 to 15 core wires 12, the ratio of the core wires 12 to the conductor portion 1 is optimized, thereby reducing stress due to twisting action and conductor interference between the bare wires 11, and the optimal filling degree of the core wires 12 optimally enhances durability.

[0045] 5, in the reinforcing part 2, the string body 21 is compressed and stored in a substantially linear shape along the linear direction A in the central space formed by the annular core wire 12 of the conductor part 1. That is, the string body 21 is press-fitted into the central space. Press-fitting refers to a state in which pressure is applied to force the string body 21 into the central space.

[0046] That cord 21 is approximately linear means that, as shown in FIG. 5, cord 21 is stored in this central space in a shape that follows linear direction A, which is the direction of travel (longitudinal direction) of the cable, and maintains an approximately linear shape.

[0047] For example, even if the string body 21 is bent partially or locally, as long as it can be considered to be linear overall along the linear direction A as shown in Figure 5, this is included in the state of the string body 21 being approximately linear.

[0048] More preferably, the string 21 is stored in the central space at a period that is shorter than the spiral period of the conductor portion 1. In other words, the string 21 as an intervening part is formed in a straight state that is nearly untwisted, while the bare wire 11 is in a spirally twisted state.

[0049] As a result, the intermediate cord 21 is pressed into this central portion in a state close to straight insertion, maintaining a highly straight, linear state, and the cable is formed with cord 21 maintaining a soft state rather than the hard state of being twisted, thereby further improving the cushioning properties of cord 21 and further improving the durability of the cable.

[0050] The cord body 21 is made of a plurality of threads 21a of a fiber material. For example, the cord body 21 can be made of a plurality of twisted threads 21a as shown in Fig. 6(a).

[0051] It is preferable that the cross-sectional diameter e of this cord body 21 in the natural placement shown in Figure 6(b) is larger than the cross-sectional diameter E of the central space formed in the center of the cable closer to the conductor portion 1 as shown in Figure 6(c).

[0052] 6(d), the cross-sectional area of ​​the cord 21 constituting the reinforcing part 2 in natural placement is larger than the cross-sectional area of ​​the central space of the cable, and is configured to be bulkier than the cross-sectional area of ​​this central space. In this way, the cord 21 as an intermediate is pressed into this central part in a highly compressed state, and the cable is formed while the cord 21 maintains a highly flexible state, improving the cushioning of the cord 21 and further improving the durability of the cable.

[0053] The cord 21 is not particularly limited as long as it is made of a fiber material, and may be made of a natural material, but it is preferable that the cord 21 be made of synthetic fibers in terms of uniform quality and cost.

[0054] The synthetic fiber is not particularly limited, but examples thereof include polyester resin, acrylic resin, rubber resin, vinyl alkyl ether resin, silicone resin, polyamide resin, urethane resin, fluorine resin, and epoxy resin. From the viewpoint of ease of handling, it is preferable to use polyester, more preferably polyester, and even more preferably cotton-like polyester. For example, polyester nonwoven fabric can be made into a third count thread 21a and twisted in three strands, and multiple strands of this can be used for the cord body 21 as an intermediate.

[0055] Since the string 21 is made of synthetic fiber, the string 21 made of highly flexible synthetic fiber is pressed into the center of the cable, making it easier to pack more of the string 21 in the center than the theoretically calculated cross-sectional area. This reduces the contact pressure between the bare wires 11, and the string 21 made of cushioned synthetic fiber in the center supports the cable with a force that moves radially from the center of the cable toward the outer periphery. This ensures that the string 21 remains soft when the cable is formed, further improving the durability of the cable.

[0056] The insulating covering material 3 that covers the conductor portion 1 is not particularly limited as long as it is an insulating material, but for example, it can be composed of multiple materials including a pressing tape 31 that covers the outer periphery of the conductor portion 1 and presses and fixes the conductor portion 1 in a tape-like manner, an insulating material 32 that covers the outer periphery of the pressing tape 31, and a sheath 33 that covers the outer periphery of the insulating material 32 and prevents damage to the cable.

[0057] The material of this pressing tape 31 is not particularly limited, but for example, a fluororesin tape can be used. Examples of such fluororesins include various materials such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (tetrafluoroethylene-ethylene copolymer), PVDF (polyvinylidene difluoride), PCTFE (polychlorotrifluoroethylene), ECTFE (chlorotrifluoroethylene-ethylene copolymer), and PTFE (polytetrafluoroethylene). By using such a tape, the conductor portion 1 inside the cable is not restricted due to its flexible properties of high slipperiness and high elasticity, and durability can be further improved.

[0058] The insulating material 32 is preferably made of a material having a higher bending elasticity than the material of the sheath 33 .

[0059] The material of the insulating material 32 is not particularly limited as long as it is an insulating material, and for example, various resins such as thermoplastic ester elastomer (TPEE), thermoplastic olefin elastomer (TPO), thermoplastic urethane elastomer (TPU), and thermoplastic amide elastomer (TPAE) can be used. More specifically, for example, PEs (polyester), PBT (polybutylene terephthalate), PE (polyethylene), PP (polypropylene), PA6 (polyamide 6), PA11 (polyamide 11), PA12 (polyamide 13), and the like can be used. Examples of materials that can be used include (polyamide 12), PET (polyethylene terephthalate), PBN (polybutylene naphthalate), PVDF (polyvinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PTFE (polytetrafluoroethylene), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), EVOH (ethylene-vinyl alcohol copolymer), ABS (acrylonitrile-butadiene-styrene), EVA (ethylene vinyl alcohol), and PI (polyimide).

[0060] For example, polyester elastomer can be used as the insulating material 32. In this case, the bending elasticity is higher than that of PVC, and the hardness of the material prevents the stress of torsion from concentrating on the terminal portion. In addition, since the material can be molded by pipe extrusion, the durability can be maintained without restraining the conductor, and the stress on the core wire 12 during cable manufacturing can be reduced, allowing the manufacture of a high-quality cable.

[0061] The rigidity of the insulating material 32 is not particularly limited, but from the viewpoint of enhancing durability, it is preferable that the rigidity is 50 MPa to 400 MPa, and more preferably, 70 MPa to 300 MPa. From this viewpoint, it is preferable to select the insulating material 32 of a grade that can withstand 10 million bending cycles even when bent with a bending radius of 6D (mm).

[0062] The material of this sheath 33 is not particularly limited, but examples include PVC (polyvinyl chloride), PE (polyethylene), FEP (Teflon (registered trademark)), etc., and for ease of handling, PVC (polyvinyl chloride) can be used, which is flexible, flame-retardant, and oil-resistant and has a proven track record in welding robot cables.

[0063] In this way, the string body 21 is pressed into the center of the cable, and the amount of string body 21 stored in this center is greater than the theoretically calculated cross-sectional area. This reduces the contact pressure between the bare wires 11, and the string body 21, which has cushioning properties in the center, supports the cable with a force that flows radially from the center of the cable toward the outer periphery of the cable. This significantly improves cable durability, for example, during twisting operations performed by a welding robot, thereby making it possible to suppress the occurrence of cable breakage.

[0064] In addition, since the cable is made up of bare wires 11 (child twisted wires) that are not isolated from each other by insulating materials or tape, the terminals can be easily joined and high processability is obtained. Compared to conventional technology, which requires stripping the coated wires of the multiple child twisted wires that make up the cable and joining them at the terminals, this makes it easier to handle and reduces manufacturing costs.

[0065] Second Embodiment The cable 10 of the second embodiment comprises the conductor portion 1, the conductor portion 1, and the reinforcing portion 2, similar to the first embodiment, and further has a configuration in which a gap 13 is formed in the area formed between the adjacent conductor portion 1 and the insulating coating material 3, as shown in Figure 7.

[0066] The gap 13 preferably occupies at least a part of the region formed between the adjacent conductor portion 1 and the insulating covering material 3. More preferably, the gap 13 occupies the entire region.

[0067] In this way, since the gap 13 is formed in the region formed between the adjacent conductor portions 1 and the insulating coating material 3, when the cable is used with repetitive motions such as twisting motions in a welding robot, the gap 13 acts like a buffer material, significantly improving cable durability and preventing breakage. In addition, since cutting of members in this region is not required during cable production, processability is improved and production costs can be reduced.

[0068] In order to further clarify the features of the present invention, examples are given below, but the present invention is not limited to these examples.

[0069] Example 1 (1) Cable production According to the first embodiment described above, a cable according to Example 1 was produced using the following members. <Materials> Core wire 12: Tin-plated soft copper wire (composite stranded conductor) (each cable cross-sectional area 2sq x 10 wires) · String body 21: Polyester (highly cushioned interposition) -Pressing tape 31: Fluorine tape Insulation 32: Polyester elastomer Sheath 33: PVC Outer diameter of conductor part 1: 9.2 (theoretical calculation ratio)

[0070] (2) Verify the number of cores The outer diameter of a cable varies depending on the number of core wires 12 that make up the cable. Figure 8 shows the results of calculating the outer diameter when a 22sq conductor is divided into 1 to 12 (when the number of core wires is 1 to 12).

[0071] As mentioned above, the number of core wires is preferably 6 to 15, but from the viewpoint of reducing the outer diameter of the cable, it was confirmed from the measurement results in Fig. 8 that a more preferable number is 8 to 12. This confirmed that the outer diameter of the cable can be reduced, and a highly durable cable can be realized in a compact size.

[0072] Example 2 A comparison test of twist durability was carried out between the cable produced in Example 1 and a conventional cable, HMVV (c10681) AWG4 (22) / 1C (manufactured by DAIDEN Co., Ltd.) The test conditions were as shown in Fig. 9(a), with the distance L between the fixed end and the movable end of the subject cable being 200 mm, the twist angle θ being ±180°, and the number of twist repetitions being 5 million.

[0073] The results are shown in Figure 9(b). From these results, it was confirmed that 36.7% of the conductor wires (bare wires 11) broke in the conventional cable. In contrast, it was confirmed that 0.21% of the conductor wires (bare wires 11) broke in the cable of this embodiment, which means that almost no breaks occurred. From this, the difference in durability with the conventional product was significant, and extremely high durability was confirmed.

[0074] The results of the twisting test for each cable (conductor appearance) are shown in Figure 10. The results show that, in the conventional cable, conductor deformation was confirmed after 5 million repeated twists, whereas in the cable of this example, no such conductor deformation occurred, and the difference in durability from the conventional cable was also significant in appearance, confirming extremely high durability. [Explanation of symbols]

[0075] 1 Conductor 11 Bare wire 12 core wire 13 void 2 Reinforcement 21 String 21a Thread 3. Insulating coating material 31 Holding Tape 32 Insulation materials 33 Sheath

Claims

1. A cable in which a conductor portion, in which a conductor is arranged in a spiral shape in the longitudinal direction, is covered with an insulating covering material having insulating properties, a conductor portion formed by twisting together a plurality of bare wires to form a core wire and arranging a plurality of the core wires in close contact with each other in a circular ring shape; a reinforcing portion formed of a string body made of a plurality of threads of a fiber material, the string body being compressed and stored in a substantially linear shape within a central space formed by the annular core wire of the conductor portion; Equipped with The cord is press-fitted into the central space. cable.

2. 2. The cable according to claim 1, The cross-sectional area of ​​the cord body in its natural state is larger than the cross-sectional area of ​​the central space. cable.

3. 2. The cable according to claim 1, The cord is made of synthetic fiber. cable.

4. 2. The cable according to claim 1, The reinforcing portion is characterized in that the string is accommodated in the central space at a period that is smaller than the spiral period of the conductor portion. cable.

5. 2. The cable according to claim 1, The core wires are closely connected to each other at a plurality of points. cable.

6. 2. The cable according to claim 1, The diameter of the conductor is 3 to 6 times the diameter of the core wire. cable.

7. 2. The cable according to claim 1, The diameter of the core wire is 8 to 60 times the diameter of the bare wire. cable.

8. 2. The cable according to claim 1, A gap is formed in a region between the adjacent conductor portion and the insulating coating material. cable.

9. The cable according to any one of claims 1 to 8, The conductor portion is characterized in that it is composed of 6 to 15 of the core wires. cable.

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