Cable

Abstract

To provide a cable which can reduce environmental loads and prevents deterioration even when operation such as bending is imparted.SOLUTION: A cable 1 includes an assembly core 3 formed by twisting a plurality of insulated wires 2, and a sheath 5 covering the periphery of the assembly core 3, where the insulated wire 2 has a conductor 21 composed of a plurality of element wires, and an insulator 22 covering the periphery of the conductor 21, the insulator 22 is composed of a non-fluororesin, and the insulated wire 2 has conductor drawing force which is a force of drawing the conductor 21 from the insulator 22 in a longitudinal direction of 3.5 kgf / 25 mm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cable. [Background technology]

[0002] An example of a cable to be wired to a robot (or a machine tool), such as an industrial robot, is a cable that includes an aggregate core made of multiple insulated wires twisted together and a sheath that covers the aggregate core (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-218061 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, in order to reduce the environmental impact, it has become desirable not to use fluororesin as the insulator of insulated electric wires. On the other hand, if the insulator of an insulated electric wire is made of a resin other than fluororesin (for example, a non-fluororesin such as polypropylene), the cable may be easily deteriorated (especially the conductor may break) when the cable is repeatedly bent or twisted.

[0005] Therefore, an object of the present invention is to provide a cable that can reduce the environmental load and is less likely to deteriorate even when subjected to movements such as bending. [Means for solving the problem]

[0006] The present invention aims to solve the above-mentioned problems by providing a cable comprising: an aggregate core in which a plurality of insulated wires are twisted together; and a sheath covering the periphery of the aggregate core, wherein the insulated wire has a conductor consisting of a plurality of strands and an insulator covering the periphery of the conductor, the insulator being made of a non-fluorine resin; and the insulated wire has a conductor pull-out force, which is the force exerted when the conductor is pulled out of the insulator in the longitudinal direction, of 3.5 kgf / 25 mm or less. Effect of the Invention

[0007] According to the present invention, it is possible to provide a cable which can reduce the environmental load and is resistant to deterioration even when subjected to bending or other operations. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating a bending test of an insulated wire. [Diagram 3] FIG. 11 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable according to a modified embodiment of the present invention. [Figure 4] FIG. 11 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable according to a modified embodiment of the present invention. [Diagram 5] FIG. 11 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable according to a modified embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0010] 1 is a cross-sectional view perpendicular to the longitudinal direction of a cable 1 according to the present embodiment. Cable 1 is used in, for example, an industrial robot or other device, and is routed so as to pass through a movable part of the device. Cable 1 is given motions such as bending and twisting in response to the movement of the movable part.

[0011] As shown in Fig. 1, the cable 1 includes an aggregate core 3 in which a plurality of insulated wires 2 are twisted together, and a sheath 5 that covers the periphery of the aggregate core 3. In this embodiment, a tape member 4 is wound around the periphery of the aggregate core 3, and the sheath 5 is provided so as to cover the periphery of the tape member 4. The thickness and outer diameter of each part, which will be described later, can be measured by the test method specified in JISC3005.

[0012] (Collective Core 3) The collective core 3 has an insert 6 arranged at the center of the cable and ten insulated electric wires 2 twisted around the insert 6. When the cable 1 is subjected to bending, twisting, or other operations, the load at the center of the cable is likely to be large. Therefore, in this embodiment, the insert 6 is arranged at the center of the cable, and the insulated electric wire 2 is not arranged at the center of the cable, thereby improving resistance to bending, twisting, and the like (i.e., the wires constituting the conductor 21 are less likely to break even if the cable 1 is repeatedly subjected to bending and twisting operations). In this embodiment, the collective core 3 is constituted by ten insulated electric wires 2, but the number of insulated electric wires 2 constituting the collective core 3 is not limited to this. In addition, the multiple insulated electric wires 2 constituting the collective core 3 may be twisted in pairs in the cable circumferential direction in a state of twisted wires in which two wires are twisted together. By twisting the multiple insulated electric wires 2 in a state of twisted wires, the cable 1 can be used as a signal transmission cable or a control cable. Details of the insulated electric wires 2 will be described later.

[0013] The filler 6 may be a bundle of many fiber threads made of staple fiber or the like. However, the present invention is not limited to this, and may be, for example, a solid or hollow filler 6 made of one or more linear (cylindrical) resin strands. The filler 6 may also be made of both of these. In the illustrated example, the filler 6 is not disposed between the insulated electric wire 2 and the tape member 4, but the filler 6 may be disposed between the insulated electric wire 2 and the tape member 4.

[0014] (Tape member 4) The tape member 4 is a member for holding the collective core 3 so that it does not untwist, and is made of a resin tape such as PET (polyethylene terephthalate). The tape member 4 is wound in a spiral shape so that parts of the tape member 4 overlap each other in the width direction. The tape member 4 may be formed by winding a plurality of resin tapes in a spiral shape. For example, the tape member 4 may be formed by winding a resin tape such as the above-mentioned PET in a spiral shape around the collective core 3, and a resin tape that also functions as a noise suppressing member in a spiral shape around the periphery of the resin tape. In this case, it is preferable that the two resin tapes are wound in the same direction as the direction in which the multiple insulated electric wires 2 that constitute the collective core 3 are twisted together. As the resin tape that also functions as a noise suppressing member, for example, a resin tape having electrical conductivity can be used. As the resin tape having electrical conductivity, for example, a resin layer that is a base material and has electrically conductive particles dispersed therein, or a resin layer having electrical conductivity provided on the surface of the resin layer, may be used. In addition, a drain wire may be wound between the two resin tapes in the same direction as the winding direction of the two resin tapes. This makes it difficult for the drain wire to break when the cable 1 is repeatedly bent, twisted, or the like, and even if the drain wire does break, it is possible to prevent the drain wire from piercing the insulated wire 2 and damaging the insulated wire 2. The drain wire is made of a bunched twisted wire in which a plurality of metal wires, such as soft copper wires or copper alloy wires, having a tin-plated surface, are bunched and twisted. Since the drain wire is made of a bunched twisted wire, the cross-sectional shape of the drain wire can be deformed into a non-circular shape, such as an ellipse, when the drain wire is disposed between two resin tapes, and therefore unevenness is unlikely to occur on the surface of the tape member 4. This makes it difficult for the cross-sectional shape of the cable 1 to become distorted in the cable circumferential direction even in a structure in which the drain wire is disposed between two resin tapes, and makes it possible to prevent a decrease in resistance when the cable 1 is repeatedly bent, twisted, or the like. The outer diameter of the plurality of metal wires constituting the drain wire is preferably 0.05 mm or more and 0.12 mm or less. The cross-sectional area of ​​the drain wire is 0.2 mm or less. 2 More than 2.5mm 2 The thickness of the tape member 4 is, for example, not less than 0.03 mm and not more than 0.30 mm.

[0015] (Sheath 5) The sheath 5 is a layer for protecting the aggregate core 3, and is made of, for example, a resin composition having a polyvinyl chloride resin as a base resin. The inner surface of the sheath 5 is provided in contact with the outer surface of the tape member 4. The thickness of the sheath 5 is, for example, 0.80 mm or more and 1.5 mm or less.

[0016] (Insulated Wire 2) The insulated wire 2 has a conductor 21 formed by twisting together a plurality of wires, and an insulator 22 covering the conductor 21. In this embodiment, two types of insulated wires 2 having different conductor cross-sectional areas and outer diameters are used as the insulated wires 2 constituting the assembly core 3. Here, the two insulated wires 2 having a smaller conductor cross-sectional area and outer diameter are referred to as the first insulated wire 2a, and the eight insulated wires 2 having a larger conductor cross-sectional area and outer diameter than the first insulated wire 2a are referred to as the second insulated wire 2b. The first insulated wire 2a has a first conductor 21a and a first insulator 22a covering the first conductor 21a. The second insulated wire 2b has a second conductor 21b and a second insulator 22b covering the second conductor 21b.

[0017] In order to improve resistance to bending and twisting, the conductor 21 is desirably formed by twisting together a large number of thin-diameter element wires made of metal wires. In addition, in the case of a concentrically twisted wire in which a plurality of element wires are twisted concentrically, the relative movement of each element wire is hindered, and the element wires are likely to break when the cable 1 is repeatedly bent or twisted. Therefore, the conductor 21 is desirably formed by a bunched twisted wire in which a plurality of element wires are bunched and twisted. More specifically, the conductor 21 is desirably formed by bunching together a plurality of element wires having an outer diameter of 0.08 mm or more and 0.12 mm or less. By setting the outer diameter of the element wire to 0.08 mm or more, the element wires become less likely to break, and by setting the outer diameter of the element wire to 0.12 mm or less, the number of element wires used in the conductor 21 can be increased to improve resistance to bending and twisting. The number of element wires is, for example, 30 or more.

[0018] In addition, it is preferable to use a wire made of a soft material, and it is preferable to use a wire made of soft copper or a soft copper alloy. More specifically, when a soft copper wire is used as the wire, the elongation of the wire is preferably 10% or more, and the tensile strength of the wire is preferably 220 MPa or more and 300 MPa or less. When a copper alloy wire is used as the wire, it is preferable to use a soft copper alloy wire having an elongation of 5% or more and a tensile strength of 320 MPa or more and 450 MPa or less. A wire made of a soft material (soft wire) is obtained by subjecting a wire having the above-mentioned outer diameter immediately before being twisted to a heat treatment under a predetermined condition. The wire is heated before twisting a plurality of wires together, or in the state of the conductor 21 after twisting a plurality of wires together. The elongation and tensile strength of the wire can be measured by the test method for "breaking elongation" and "tensile strength" specified in JIS Z2241.

[0019] The cross-sectional area of ​​the insulated wire 2 is 0.2 mm 2 More than 2.5mm 2 It is preferable that the value is less than or equal to 0.5 mm. 2 2.3mm or more 2 More specifically, the conductor cross-sectional area of ​​the first insulated wire 2a is 0.2 mm 2 More than 0.8mm 2 It is preferable that the thickness is less than 0.5 mm. 2 More than 0.8mm 2 The conductor cross-sectional area of ​​the second insulated wire 2b is less than 0.8 mm 2 More than 2.5mm 2 It is preferable that the value is less than or equal to 1.0 mm, and more preferably, the value is less than or equal to 1.0 mm. 2 2.3mm or more 2 The conductor cross-sectional area of ​​the first insulated electric wire 2a is preferably at least ¼ the conductor cross-sectional area of ​​the second insulated electric wire 2b. This is because if the difference in the conductor cross-sectional area of ​​the two insulated electric wires 2a, 2b is too large, there is a risk that the difference (variation) in resistance to bending and twisting between the two insulated electric wires 2a, 2b will become large. The conductor cross-sectional area can be found by multiplying the cross-sectional area of ​​the metal wire calculated from the outer diameter of the metal wire (element wire) by the number of metal wires.

[0020] In this embodiment, in order to reduce the environmental load, a resin other than fluororesin, that is, a non-fluororesin, is used as the insulator 22.

[0021] In this embodiment, since the conductor pull-out force of the insulated wire 2 is 3.5 kgf / 25 mm or less, when the cable 1 is repeatedly bent or twisted, the conductor 21 moves relative to the insulator 22, and friction may occur between the conductor 21 and the insulator 22. In order to suppress breakage of the wires of the conductor 21 due to this friction, that is, to improve resistance to bending and twisting, it is preferable to use an insulator 22 that has a large elongation. More specifically, it is preferable that the elongation of the insulator 22 is at least 500% or more. By increasing the elongation of the insulator 22 to 500% or more, it is possible to suppress breakage of the wires of the conductor 21 due to friction between the insulator 22 and the conductor 21, and improve resistance to bending and twisting. As the non-fluorine resin used for the insulator 22, it is preferable to use an olefin resin such as polypropylene or polyethylene, a non-halogen resin that does not contain halogen substances, or the like. In particular, it is preferable to use an olefin resin that can satisfy both the above-mentioned conductor pull-out force and the elongation of the insulator 22, and in particular, the use of polypropylene makes it easier to obtain the above-mentioned conductor pull-out force of the insulated wire 2. This olefin resin may be a cross-linked olefin resin obtained by cross-linking polypropylene, polyethylene, or the like.

[0022] The insulator 22 may be formed to have a hollow cylindrical cross section by tube extrusion molding. This allows the conductor 21 to move easily inside the insulator 22, improving resistance to bending and twisting. In the collective core 3, in a cross section perpendicular to the longitudinal direction (cable longitudinal direction) of the cable 1, two first insulated electric wires 2a are arranged to face each other across the center (cable center) of the cable 1, and four second insulated electric wires 2b are arranged between each of the two first insulated electric wires 2a in the circumferential direction (cable circumferential direction) of the cable 1. This allows the first insulated electric wires 2a and the second insulated electric wires 2b to be evenly arranged in the cable circumferential direction, thereby suppressing problems such as difficulty in bending in a specific direction. However, the arrangement of the first insulated electric wires 2a and the second insulated electric wires 2b is not limited to this, and for example, two first insulated electric wires 2a may be arranged adjacent to each other in the cable circumferential direction.

[0023] However, when a non-fluorinated resin such as polypropylene is used for the insulator 22, the wires constituting the conductor 21 and the insulator 22 may adhere strongly to each other in some parts, and when the cable 1 is repeatedly bent or twisted, stress may concentrate on the wires in the adhered parts, causing them to break. In particular, when using a conductor 21 that is made of a bunched stranded wire that uses many thin wires with an outer diameter of 0.08 mm or more and 0.12 mm or less and in which the individual wires are not uniformly arranged, there are likely to be parts where the wires and the insulator 22 adhere strongly to each other.

[0024] Therefore, in this embodiment, the conductor pull-out force of the insulated wire 2 is set to 3.5 kgf / 25 mm or less. Here, the conductor pull-out force is the force when the conductor 21 is pulled out from the insulator 22 at a constant speed (for example, a speed of 50 mm / min) in the longitudinal direction, and the conductor pull-out force of 3.5 kgf / 25 mm indicates that the force required when the conductor 21 covered with the insulator 22 is pulled out from the insulator 22 at a constant speed in the insulated wire 2 having a length of 25 mm is 3.5 kgf (34.3 N). By setting the conductor pull-out force of the insulated wire 2 to 3.5 kgf / 25 mm or less, the adhesion of the wires constituting the conductor 21 to the insulator 22 is suppressed, and the conductor 21 becomes relatively easy to move within the insulator 22. As a result, it is possible to suppress breakage due to stress concentration on some of the wires as described above, and improve resistance to bending and twisting.

[0025] The conductor pull-out force can be adjusted by adjusting the manufacturing speed (linear speed) when the insulator 22 is formed by tube extrusion and the temperature of the insulator 22 immediately after the tube extrusion. That is, the conductor pull-out force of the insulated electric wire 2 can be set to 3.5 kgf / 25 mm or less by appropriately adjusting the manufacturing speed (linear speed) when the insulator 22 is formed into a hollow cylindrical shape by tube extrusion molding and the temperature of the insulator 22 immediately after the tube extrusion. For example, when the manufacturing speed (linear speed) is increased, the resin constituting the insulator 22 is cooled faster, and as a result, the adhesive force between the insulator 22 and the conductor 21 is reduced, and the conductor pull-out force is reduced. It is more preferable that the conductor pull-out force of the insulated electric wire 2 is set to 3.0 kgf / 25 mm or less. Moreover, if the conductor pull-out force of the insulated electric wire 2 is too small, the conductor 21 is easily pulled out of the insulator 22, making it difficult to handle the insulated electric wire 2. Therefore, the conductor pull-out strength of the insulated wire 2 is more preferably 0.5 kgf / 25 mm or more. In other words, the conductor pull-out strength of the insulated wire 2 is more preferably 0.5 kgf / 25 mm or more and 3.0 kgf / 25 mm or less. This makes it possible to provide the cable 1 with improved both the handleability of the insulated wire 2 and resistance to bending and twisting.

[0026] The thickness of the insulator 22 is preferably at least twice the outer diameter of the wire used in the conductor 21. For example, the thickness of the insulator 22 is at least 0.16 mm and at most 0.30 mm. This makes it possible to prevent the broken wire from breaking through the insulator 22 and becoming exposed when the wire is broken.

[0027] When polypropylene is used as the insulator 22, the tensile strength of the insulator 22 is preferably 25 MPa or more and 34 MPa or less. As described above, the tensile strength of the strand is preferably at least 450 MPa or less, and the tensile strength of the strand is preferably at least 20 times the tensile strength of the insulator 22.

[0028] In the present embodiment, the aggregate core 3 includes two types of insulated electric wires 2a, 2b having different conductor cross-sectional areas and outer diameters. When the aggregate core 3 includes insulated electric wires 2 having different conductor cross-sectional areas and outer diameters, it is desirable that each of the insulated electric wires 2 individually has the same resistance to bending and twisting. This is because if one of the insulated electric wires 2 included in the aggregate core 3 breaks, it is determined that the life of the entire cable 1 has ended. In order to maintain a long life of the entire cable 1, it is desirable that each of the insulated electric wires 2 included in the aggregate core 3 has the same resistance to bending and twisting.

[0029] In this embodiment, the assembly core 3 has a first insulated electric wire 2a and a second insulated electric wire 2b having a larger conductor cross-sectional area and outer diameter than the first insulated electric wire 2a. In this case, in order to reduce the difference (variation) in resistance to bending and twisting between the first insulated electric wire 2a and the second insulated electric wire 2b (i.e., to make the resistance to bending and twisting of each insulated electric wire 2 included in the assembly core 3 equal), the conductor pull-out force of the first insulated electric wire 2a may be different from that of the second insulated electric wire 2b within a range of 3.5 kgf / 25 mm or less. In this case, the conductor pull-out forces of the multiple first insulated electric wires 2a may be different from each other, and the conductor pull-out forces of the multiple second insulated electric wires 2b may be different from each other. By reducing the difference (variation) in resistance to bending and twisting between the insulated electric wires 2, the life of the entire cable 1 can be extended. Here, the term "life" means that the conductor 21 constituting the insulated wire 2 reaches a state where it is determined that the conductor 21 has broken when the cable 1 is repeatedly bent and twisted. Examples of the state where it is determined that the conductor 21 has broken include when the resistance increase rate of the conductor 21 constituting the cable 1 exceeds a preset value (e.g., 20%) or when all of the multiple wires constituting the conductor 21 are broken (total breakage). The resistance increase rate is the ratio of the increase in the resistance value of the conductor 21 when the cable 1 is repeatedly subjected to the above-mentioned operation to the resistance value (initial resistance value) of the conductor 21 before the cable 1 is subjected to the above-mentioned operation.

[0030] In order to reduce the difference (variation) in resistance to bending and twisting between the first insulated electric wire 2a and the second insulated electric wire 2b, the elongation of the second insulator 22b in the second insulated electric wire 2b may be made different from the elongation of the first insulator 22a in the first insulated electric wire 2a. This is because the stress (tensile force on the outside of the bend) applied to the second insulator 22b when bent is larger in the second insulated electric wire 2b, which has an outer diameter larger than that of the first insulated electric wire 2a. In this case, the elongation of the first insulator 22a of each of the multiple first insulated electric wires 2a may be made different from each other, and the elongation of the second insulator 22b of each of the multiple second insulated electric wires 2b may be made different from each other. By reducing the difference (variation) in resistance to bending and twisting between the first insulated electric wire 2a and the second insulated electric wire 2b, the life of the entire cable 1 can be extended. More specifically, the first insulator 22a may have an elongation value of 790% or more as measured using a test method conforming to JISC3005. The second insulator 22b may have an elongation value of 810% or more as measured using a test method conforming to JISC3005. In order to reduce the difference (variation) in resistance to bending and twisting between the first insulated electric wire 2a and the second insulated electric wire 2b, the difference between the elongation of the second insulator 22b in the second insulated electric wire 2b and the elongation of the first insulator 22a in the first insulated electric wire 2a may be 60% or less. The elongation value of each of the first insulator 22a and the second insulator 22b can be measured using a test method conforming to JISC3005.

[0031] (Bending test for the first insulated wire 2a and the second insulated wire 2b) Five first insulated electric wires 2a each having a first insulator 22a with a hollow cylindrical cross section formed by tube extrusion around a first conductor 21a made of soft wires, and five second insulated electric wires 2b each having a hollow cylindrical cross section formed by tube extrusion around a second conductor 21b made of soft wires, were produced and subjected to bending tests. In the first insulated electric wire 2a, the first conductor 21a is a bunched stranded wire (conductor cross-sectional area: 0.5 mm2) in which multiple strands with an outer diameter of about 0.12 mm are bunched and twisted. 2), and the first insulator 22a is polypropylene having an elongation value of 790% or more and 815% or less. In the second insulated wire 2b, the second conductor 21b is a bunched stranded wire (conductor cross-sectional area: 1.8 mm 2 ), and the second insulator 22b is polypropylene having an elongation value of 810% or more and 850% or less. When the conductor pull-out strength of the prototype first insulated electric wire 2a and the prototype second insulated electric wire 2b was measured, both were 0.5 kgf / 25 mm or more and 3.0 kgf / 25 mm or less.

[0032] In the bending test, as shown in Fig. 2, one end of the insulated electric wire 2 to be tested was fixed, and a weight was hung from the other end to apply a load W of 0.3 kgf (2.94 N), and the insulated electric wire 2 was repeatedly bent 90 degrees to the left and right. The number of tests was defined as one cycle of bending 90 degrees to the right from an unbent neutral position (arrow a), returning to the neutral position (arrow b), bending 90 degrees to the left from the neutral position (arrow c), and returning to the neutral position (arrow d), and the cycle was repeated at a speed of 30 times per minute. The bending radius was 5 mm, and the wire was judged to have broken when the conductor 21 was completely broken.

[0033] In the five first insulated electric wires 2a, the conductor 21 broke after 2000 or more bends. The average number of bends when breakage occurred was 3000 or more. In the five second insulated electric wires 2b, the conductor 21 broke after 2500 or more bends. The average number of bends when breakage occurred was 3000 or more. From the above results, it was confirmed that even when using the first insulated electric wires 2a and the second insulated electric wires 2b having different conductor cross-sectional areas and outer diameters, the same bending resistance can be obtained by setting the conductor pull-out force to 3.0 kgf / 25 mm or less. Therefore, by forming the collective core 3 using the insulated electric wires 2 with a conductor pull-out force of 3.0 kgf / 25 mm or less, the difference (variation) in resistance to bending and twisting within the collective core 3 can be reduced, and therefore the resistance to bending and twisting of the entire cable 1 can be improved.

[0034] (Modification) In the above embodiment, the case where the collective core 3 is formed using the insulated electric wires 2a, 2b having different conductor cross-sectional areas and outer diameters has been described. However, the present invention is not limited to this. As in the cable 1a shown in Fig. 3, all the insulated electric wires 2 constituting the collective core 3 may have the same conductor cross-sectional area and outer diameter. The conductor cross-sectional area of ​​the insulated electric wires 2 may be, for example, 0.5 mm 2 2.3mm or more 2 The assembly core 3 may be configured using three or more types of insulated wires 2 with different conductor cross-sectional areas or outer diameters. In this case, it is desirable to increase the conductor pull-out force for insulated wires 2 with smaller conductor cross-sectional areas. It is also desirable to increase the elongation of insulator 22 for insulated wires 2 with larger outer diameters. In cable 1a shown in Fig. 3, multiple twisted pairs, in which every two insulated wires 2 are twisted together, may be twisted together in the assembly core 3 along the circumferential direction of the cable.

[0035] 4, the aggregate core 3 may be formed by twisting a plurality of insulated electric wires 2 together in layers. In the cable 1b, the aggregate core 3 is formed by twisting a plurality of insulated electric wires 2 together in two layers, an inner layer 3a located on the inside in the cable radial direction and an outer layer 3b located on the outside in the cable radial direction, but the number of layers in the aggregate core 3 is not limited to this and may be three or more. The conductor cross-sectional area of ​​the insulated electric wires 2 is, for example, 0.5 mm 2 2.3mm or more 2 In the cable 1b shown in Fig. 4, both the inner layer 3a and the outer layer 3b of the assembled core 3 may be formed by twisting a plurality of twisted pairs, each of which is formed by twisting two insulated wires 2 together, in the circumferential direction of the cable.

[0036] When the collective core 3 is configured with two layers like the cable 1b, it is desirable to provide a contact prevention member 7 between the inner layer 3a and the outer layer 3b to prevent the insulated wires 2 configuring the inner layer 3a from contacting the insulated wires 2 configuring the outer layer 3b. This prevents the insulated wires 2 configuring the inner layer 3a from repeatedly rubbing against the insulated wires 2 configuring the outer layer 3b when the cable 1 is repeatedly bent or twisted, making it possible to improve resistance to bending and twisting.

[0037] In this embodiment, the contact prevention member 7 is configured with the fibrous interposition 6, but the contact prevention member 7 may be configured with a tape member having cushioning properties wrapped around the inner layer 3a. By using a tape member having cushioning properties as the contact prevention member 7, the distance between the inner layer 3a and the outer layer 3b can be made smaller than when the fibrous interposition 6 is used, while reliably suppressing contact between the inner layer 3a and the outer layer 3b. Therefore, the diameter of the cable 1 can be made smaller, and wear of the insulator 22 caused by friction between the tape member and the insulated electric wire 2 can be suppressed. As the tape member having cushioning properties, for example, a resin tape having a plurality of bubbles (polyethylene tape, polypropylene tape, etc.) can be used.

[0038] In the cable 1b, all the insulated wires 2 constituting the assembly core 3 have the same configuration, but as in the cable 1c shown in Fig. 5, the assembly core 3 may include insulated wires 2 with different conductor cross-sectional areas and outer diameters. In the cable 1c, the inner layer 3a is made up of six first insulated wires 2a having a smaller conductor cross-sectional area and outer diameter, and the outer layer 3b is made up of twelve second insulated wires 2b having a larger conductor cross-sectional area and outer diameter than the first insulated wires 2a. The conductor cross-sectional area of ​​the first insulated wires 2a constituting the inner layer 3a is, for example, 0.5 mm 2 More than 0.8mm 2 The conductor cross-sectional area of ​​the second insulated wire 2b constituting the outer layer 3b is, for example, less than 1.0 mm 2 2.3mm or more 2In the inner layer 3a, the first insulated electric wires 2a are arranged in a state of being in contact with each other along the circumferential direction of the cable or with the intervening space 6 interposed therebetween. In the outer layer 3b, the second insulated electric wires 2b are arranged in a state of being in contact with each other along the circumferential direction of the cable or with the intervening space 6 interposed therebetween. In this way, when insulated electric wires 2 having different conductor cross-sectional areas or outer diameters are used in the collective core 3, the resistance to bending and twisting can be further improved by arranging the first insulated electric wires 2a (insulated electric wires 2 having a small conductor cross-sectional area or outer diameter) having a relatively small mechanical strength in the inner layer 3a. In the cable 1c shown in FIG. 5, the inner layer 3a of the collective core 3 may be configured by twisting a plurality of twisted pairs, each of which is made by twisting every two first insulated electric wires 2a, along the circumferential direction of the cable, and the outer layer 3a of the collective core 3 may be configured by twisting a plurality of twisted pairs, each of which is made by twisting every two second insulated electric wires 2b, along the circumferential direction of the cable.

[0039] (Functions and Effects of the Embodiments) As described above, in cable 1 according to this embodiment, insulator 22 of insulated wires 2 constituting aggregate core 3 is made of non-fluorine resin, and insulated wire 2 has a conductor pull-out force of 3.5 kgf / 25 mm or less, which is the force exerted when conductor 21 is pulled out of insulator 22 in the longitudinal direction.

[0040] By setting the conductor pull-out force to 3.5 kgf / 25 mm or less so that the conductor 21 can move easily within the insulator 22, it is possible to realize high resistance to bending and twisting in each insulated electric wire 2 even when the insulator 22 is made of a non-fluorine resin. As a result, it is possible to realize a cable 1 that can reduce environmental load and is less likely to deteriorate even when repeatedly subjected to bending and other operations. In this case, it is desirable to set the elongation of the insulator 22 to 500% or more, which makes it easier to prevent breakage of the wires of the conductor 21 due to friction between the insulator 22 and the conductor 21. In addition, in the cable 1 according to the present embodiment, the conductor pull-out force is set to 3.5 kgf / 25 mm or less so that the conductor 21 can move easily within the insulator 22, so that the terminal portion of the insulated electric wire 2 is easily bent and the insulator 22 is easily stripped. As a result, even if the number of insulated electric wires 2 constituting the cable 1 is increased to improve the performance and function of a device such as a robot, it is easy to connect each terminal portion of a plurality of insulated electric wires 2 to one connector. Furthermore, when connecting the end of the cable 1 to a connector, the connection work is easy even if the interval between adjacent insulated wires 2 is set to such an extent that the insulators 22 come into contact with each other.

[0041] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[0042] [1] A cable (1) comprising: an aggregate core (3) in which a plurality of insulated wires (2) are twisted together; and a sheath (5) that covers the periphery of the aggregate core (3), wherein the insulated wires (2) have a conductor (21) consisting of a plurality of strands and an insulator (22) that covers the periphery of the conductor (21), the insulator (22) being made of a non-fluorine resin, and the insulated wire (2) has a conductor pull-out force, which is the force exerted when the conductor (21) is pulled out of the insulator (22) in the longitudinal direction, of 3.5 kgf / 25 mm or less.

[0043] [2] The cable (1) described in [1], wherein the conductor (21) is composed of a bunched strand in which a plurality of the wires made of soft copper wire or soft copper alloy having an outer diameter of 0.08 mm or more and 0.12 mm or less are bunched together.

[0044] [3] The cable (1) described in [2], wherein the tensile strength of the wires constituting the conductor (21) is less than 20 times the tensile strength of the insulator.

[0045] [4] The cable (1) described in [3], wherein the plurality of wires constituting the conductor (21) are made of soft copper wires having an elongation of 10% or more and a tensile strength of 220 MPa or more and 300 MPa or less, or soft copper alloy wires having an elongation of 5% or more and a tensile strength of 320 MPa or more and 450 MPa or less.

[0046] [5] The cross-sectional area of ​​the conductor (21) is 0.2 mm 2 More than 2.5mm 2 A cable (1) according to any one of [1] to [3] below.

[0047] [6] The cable (1) according to any one of [1] to [5], wherein the insulator (22) is made of an olefin-based resin.

[0048] [7] The cable (1) according to any one of [1] to [6], wherein the insulator (22) has an elongation of 500% or more.

[0049] [8] The cable (1) according to any one of [1] to [7], wherein the thickness of the insulator (22) of the insulated wire (2) is at least twice the outer diameter of the wire used in the conductor (21).

[0050] [9] The cable (1b, 1c) according to any one of [1] to [8], wherein the assembly core (3) is formed by twisting together a plurality of the insulated wires (2) in a layered manner.

[0051]

[10] The cable (1b, 1c) described in [9], wherein the aggregate core (3) has an inner layer (3a) located radially inward of the cable and an outer layer (3b) located radially outward of the cable, and a contact prevention member (7) is provided between the inner layer (3a) and the outer layer (3b) to prevent contact between the insulated wires (2) constituting the inner layer (3a) and the insulated wires (2) constituting the outer layer (3b).

[0052]

[11] The cable (1b, 1c) according to

[10] , wherein the contact prevention member (7) is made of a cushioning tape member wrapped around the inner layer (3a).

[0053] (Additional Note) Although the embodiment of the present invention has been described above, the invention according to the claims is not limited to the embodiment described above. It should be noted that not all of the combinations of features described in the embodiment are essential to the means for solving the problems of the invention. The present invention can be modified appropriately without departing from the spirit of the invention. [Explanation of symbols]

[0054] 1…Cable 2…Insulated wire 3. Collective core 3a…Inner layer 3b…outer layer 4…Tape member 5…Sheath 6…intervention 7…Contact prevention member 21...Conductor 22...Insulator

Claims

1. an aggregate core in which a plurality of insulated wires are twisted together; a sheath surrounding the collective core; The insulated wire has a conductor made of a plurality of wires and an insulator covering the conductor, The insulator is made of a non-fluorine resin, The insulated wire has a conductor pull-out force of 3.5 kgf / 25 mm or less, which is a force when the conductor is pulled out of the insulator in the longitudinal direction. cable.

2. The conductor is a bunched stranded wire in which a plurality of wires made of soft copper wire or soft copper alloy having an outer diameter of 0.08 mm or more and 0.12 mm or less are bunched and twisted.

2. The cable of claim 1.

3. The tensile strength of the wire constituting the conductor is less than 20 times the tensile strength of the insulator.

3. The cable of claim 2.

4. The plurality of wires constituting the conductor are A soft copper wire having an elongation of 10% or more and a tensile strength of 220 MPa or more and 300 MPa or less, or A soft copper alloy wire having an elongation of 5% or more and a tensile strength of 320 MPa or more and 450 MPa or less.

4. The cable of claim 3.

5. The cross-sectional area of ​​the conductor is 0.2 mm ２ More than 2.5 mm ２ Below is the 2. The cable of claim 1.

6. The insulator is made of an olefin-based resin.

2. The cable of claim 1.

7. The insulator has an elongation of 500% or more.

2. The cable of claim 1.

8. The thickness of the insulated wire is at least twice the outer diameter of the wire used in the conductor.

2. The cable of claim 1.

9. The core assembly is formed by twisting a plurality of the insulated electric wires together in layers.

2. The cable of claim 1.

10. The core assembly includes an inner layer located on the inside in the cable radial direction and an outer layer located on the outside in the cable radial direction, and a contact prevention member is provided between the inner layer and the outer layer to prevent contact between the insulated wires constituting the inner layer and the insulated wires constituting the outer layer.

10. The cable of claim 9.

11. The contact prevention member is made of a tape member having cushioning properties and wrapped around the inner layer.

11. The cable of claim 10.

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