Cable

Abstract

The invention provides a cable which can reduce environmental load and is not easy to deteriorate even if the cable is endowed with actions such as bending. The cable (1) is provided with an integrated core (3) formed by twisting a plurality of insulated wires (2) and a sheath (5) covering the periphery of the integrated core (3), each insulated wire (2) is provided with a conductor (21) composed of a plurality of wire rods and an insulator (22) covering the periphery of the conductor (21), the insulator (22) is composed of a non-fluororesin, and the insulated wires (2) are arranged in the sheath (5). The conductor drawing force, which is the force when the conductor (21) is drawn from the insulator (22) with respect to the longitudinal direction, is 3.5 kgf / 25 mm or less.

Description

Technical Field

[0001] The present invention relates to cables. Background Art

[0002] As a cable wired to a robot (or a machine tool) such as an industrial robot, there is a cable including a core assembly formed by twisting a plurality of insulated wires and a sheath covering the core assembly (see, for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-218061 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In recent years, in order to reduce the environmental load, it is desired not to use fluororesins as insulators for insulated wires. On the other hand, if the insulator of the insulated wire is composed of a resin other than fluororesins (for example, non-fluororesins such as polypropylene), the cable is easily degraded (especially the conductor is broken) when the cable is repeatedly bent or twisted.

[0008] Therefore, an object of the present invention is to provide a cable that can reduce environmental load and is less likely to deteriorate even when subjected to an action such as bending.

[0009] Methods for solving problems

[0010] The present invention aims to solve the above-mentioned problems and provides a cable comprising a core assembly formed by twisting a plurality of insulated wires and a sheath covering the core assembly, wherein the insulated wire has a conductor composed of a plurality of wires and an insulator covering the conductor, the insulator being made of a non-fluororesin, and wherein the force exerted when the conductor is pulled out from the insulator in the longitudinal direction, i.e., the conductor pulling force, is 3.5 kgf / 25 mm or less.

[0011] Effects of the Invention

[0012] According to the present invention, it is possible to provide a cable that can reduce environmental load and is unlikely to deteriorate even when subjected to an action such as bending. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This 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.

[0014] Figure 2 It is a figure explaining the bending test of an insulated electric wire.

[0015] Figure 3 It is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable according to a modification example of the present invention.

[0016] Figure 4 It is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable according to a modification example of the present invention.

[0017] Figure 5 It is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable according to a modification example of the present invention.

[0018] Description of Reference Numerals

[0019] 1…cable, 2…insulated wire, 3…collective core, 3a…inner layer, 3b…outer layer, 4…belt member, 5…sheath, 6…spacer, 7…contact prevention member, 21…conductor, 22…insulator. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0022] Figure 1 The cable 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of the cable 1 of this embodiment. The cable 1 is used in a device such as an industrial robot and is wired to pass through a movable part of the device. The cable 1 is subjected to bending, twisting, and other movements according to the movement of the movable part.

[0023] like Figure 1 As shown, the cable 1 includes an aggregate core 3 formed by twisting a plurality of insulated wires 2 and a sheath 5 covering the periphery of the aggregate core 3. In the present embodiment, a tape member 4 is wound around the aggregate core 3, and the sheath 5 is provided to cover the periphery of the tape member 4. It should be noted that the thickness and outer diameter of each part described later can be measured by the test method specified in JIS C3005.

[0024] (Collection Core 3)

[0025] The core assembly 3 has a spacer 6 disposed at the center of the cable and 10 insulated wires 2 twisted around the spacer 6. When the cable 1 is subjected to bending, twisting and other actions, the load at the center of the cable tends to increase. Therefore, in the present embodiment, by configuring the spacer 6 at the center of the cable, the insulated wire 2 is not disposed at the center of the cable, thereby achieving an improvement in resistance to bending, twisting, etc. (that is, even if the cable 1 is repeatedly subjected to bending and twisting actions, the wire material constituting the conductor 21 is not easy to break). In the present embodiment, 10 insulated wires 2 are used to constitute the core assembly 3, but the number of insulated wires 2 constituting the core assembly 3 is not limited thereto. In addition, the plurality of insulated wires 2 constituting the core assembly 3 may also be twisted in the circumferential direction of the cable in the state of two twisted pairs. The plurality of insulated wires 2 are twisted in the state of twisted pairs, thereby enabling the cable 1 to be used as a signal transmission cable or a control cable. Details of the insulated wires 2 will be described later.

[0026] As the spacer 6, a spacer formed by bundling a plurality of fiber yarns composed of staple fibers or the like can be used. However, the present invention is not limited thereto, and for example, a solid or hollow spacer 6 composed of one or more linear (cylindrical) resins can also be used. In addition, the spacer 6 can also be composed of both. In the example shown in the figure, the spacer 6 is not arranged between the insulated wire 2 and the belt member 4, but the spacer 6 can also be arranged between the insulated wire 2 and the belt member 4.

[0027] (Belt member 4)

[0028] The belt member 4 is a member for keeping the twist of the collective core 3 from unraveling, and is composed of, for example, a resin belt such as PET (polyethylene terephthalate). The belt member 4 is wound in a spiral shape in such a way that a portion of it overlaps in the width direction. The belt member 4 can also be formed by winding a plurality of resin belts in a spiral shape. For example, the belt member 4 can also be wound with the above-mentioned resin belt such as PET spirally around the collective core 3, and further wound with a resin belt that also functions as a noise suppression member spirally around it. At this time, the two resin belts are preferably wound in the same direction as the direction in which the plurality of insulated wires 2 constituting the collective core 3 are twisted. As a resin belt that also functions as a noise suppression member, for example, a conductive resin belt can be used. As a conductive resin belt, for example, a belt in which conductive particles are dispersed in a resin layer serving as a substrate, a belt in which a conductive layer having conductivity is provided on the surface of the resin layer, etc. In addition, between the two resin belts, a drain wire can also be wound in the same direction as the winding direction of the two resin belts. As a result, when the cable 1 is repeatedly subjected to bending, twisting and other actions, the drain wire is not easy to break, and even if the drain wire is broken, it is possible to prevent the insulated wire 2 from being damaged due to piercing the insulated wire 2. The drain wire is composed of a collective stranded wire formed by a plurality of metal wires such as soft copper wire or copper alloy wire having a tinned surface. Since the drain wire is composed of a collective stranded wire, when it is arranged between two resin belts, the cross-sectional shape of the drain wire can be deformed into a non-circular shape such as an ellipse, so it is difficult to form unevenness on the surface of the belt member 4. As a result, even if the drain wire is arranged between two resin belts, the cross-sectional shape of the cable 1 in the circumferential direction of the cable is difficult to deform, and the resistance to repeated bending, twisting and other actions can be difficult to decrease. The outer diameter of the plurality of metal wires constituting the drain wire can be greater than 0.05 mm and less than 0.12 mm. The cross-sectional area of ​​the drain wire can be 0.2 mm 2 Above and 2.5mm 2 The thickness of the belt member 4 is, for example, 0.03 mm or more and 0.30 mm or less.

[0029] (Sheath 5)

[0030] The sheath 5 is a layer for protecting the core assembly 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 belt member 4. The thickness of the sheath 5 is, for example, not less than 0.80 mm and not more than 1.5 mm.

[0031] (Insulated wire 2)

[0032] The insulated wire 2 has a conductor 21 formed by twisting a plurality of wires and an insulator 22 covering the conductor 21. In the present 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 collective core 3. Here, the two insulated wires 2 having smaller conductor cross-sectional areas and outer diameters are referred to as first insulated wires 2a, and the eight insulated wires 2 having larger conductor cross-sectional areas and outer diameters than the first insulated wires 2a are referred to as second insulated wires 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.

[0033] In order to improve the resistance to bending and torsion, the conductor 21 is preferably composed of a plurality of thin-diameter wires composed of metal wires twisted together. In addition, in the case of a concentric stranded wire formed by concentrically twisting a plurality of wires, the relative movement of each wire is hindered, and when the cable 1 is repeatedly bent and twisted, the wire is prone to breakage, so the conductor 21 is preferably composed of a collective stranded wire formed by collectively twisting a plurality of wires. More specifically, the conductor 21 is preferably composed of a plurality of wires having an outer diameter of 0.08 mm or more and 0.12 mm or less, which are collectively twisted together. By setting the outer diameter of the wire to be greater than 0.08 mm, the wire is less likely to break, and by setting the outer diameter of the wire to be less than 0.12 mm, the number of wires used in the conductor 21 can be increased to improve the resistance to bending and torsion. The number of wires is, for example, more than 30.

[0034] In addition, as the wire material, it is preferred to use a wire material made of a soft material, and a wire material made of a soft copper wire or a soft copper alloy wire may also be used. More specifically, when a soft copper wire is used as the wire material, the elongation of the wire material may be 10% or more, and the tensile strength of the wire material may be 220 MPa or more and 300 MPa or less. In addition, when a copper alloy wire is used as the wire material, 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 may be used. The wire material (soft wire material) made of a soft material is obtained by subjecting a wire material having the above outer diameter immediately before being twisted to a heat treatment under prescribed conditions. The heating treatment of the wire material is performed in a state before a plurality of wire materials are twisted or in a state of the conductor 21 after a plurality of wire materials are twisted. The elongation and tensile strength of the wire material can be measured by the test methods of "elongation at break" and "tensile strength" specified in JIS Z2241.

[0035] In addition, the conductor cross-sectional area of ​​the insulated wire 2 can be 0.2 mm 2 Above and 2.5mm 2 Below, more preferably 0.5 mm 2 Above and 2.3mm2 More specifically, the conductor cross-sectional area of ​​the first insulated wire 2a can be 0.2 mm 2 Above and less than 0.8mm 2 , more preferably 0.5 mm 2 Above and less than 0.8mm 2 In addition, the conductor cross-sectional area of ​​the second insulated wire 2b can be 0.8mm 2 Above and 2.5mm 2 Below, more preferably 1.0 mm 2 Above and 2.3mm 2 Below. Furthermore, the conductor cross-sectional area of ​​the first insulated wire 2a may be 1 / 4 times or more of the conductor cross-sectional area of ​​the second insulated wire 2b. This is because if the difference between the conductor cross-sectional areas of the two insulated wires 2a and 2b is too large, the difference (deviation) in the resistance to bending and twisting of the two insulated wires 2a and 2b may become larger. The conductor cross-sectional area can be obtained by multiplying the cross-sectional area of ​​the metal wire calculated based on the outer diameter of the metal wire (wire material) by the number of metal wires.

[0036] In the present embodiment, in order to reduce environmental load, a resin other than fluororesin, that is, a non-fluororesin is used as the insulator 22 .

[0037] In the present 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 and twisted, the conductor 21 moves relative to the insulator 22, and friction sometimes occurs between the conductor 21 and the insulator 22. In order to suppress the wire breakage of the conductor 21 caused by the friction, that is, to improve the resistance to bending and twisting, an insulator with a large elongation can be used as the insulator 22. More specifically, the elongation of the insulator 22 is preferably at least 500%. By increasing the elongation of the insulator 22 to 500% or more, the wire breakage of the conductor 21 caused by the friction between the insulator 22 and the conductor 21 can be suppressed, and the resistance to bending and twisting can be improved. As the non-fluororesin used for the insulator 22, olefin resins such as polypropylene and polyethylene, non-halogen resins that do not contain halogen substances, etc. can be used. In particular, any olefin resin that can satisfy both the above-mentioned conductor pullout force and the elongation of the insulator 22 can be used, and in particular, when polypropylene is used, the above-mentioned conductor pullout force of the insulated wire 2 can be easily obtained. The olefin resin can be a cross-linked olefin resin obtained by cross-linking polypropylene, polyethylene, etc.

[0038] The insulator 22 can be formed into a hollow cylindrical cross section by tube extrusion molding. As a result, the conductor 21 can easily move inside the insulator 22, which can improve the resistance to bending and twisting. In the collective core 3, when observed in a cross section perpendicular to the length direction of the cable 1 (cable length direction), two first insulated wires 2a are arranged in a manner opposite to the center of the cable 1 (cable center), and four second insulated wires 2b are arranged between the two first insulated wires 2a in the circumference of the cable 1 (cable circumference). As a result, the first insulated wires 2a and the second insulated wires 2b are evenly arranged in the circumferential direction of the cable, so that it is possible to suppress the undesirable situation that it is difficult to bend in a specific direction. However, the configuration of the first insulated wires 2a and the second insulated wires 2b is not limited to this. For example, two first insulated wires 2a can also be arranged adjacent to each other in the circumferential direction of the cable.

[0039] However, when non-fluorine resins such as polypropylene are used for the insulator 22, the wires constituting the conductor 21 are strongly adhered to the insulator 22 locally, and when bending and twisting are repeatedly applied to the cable 1, stress is concentrated on the wires in the adhered portion, causing wire breakage. In particular, when a plurality of thin wires having an outer diameter of 0.08 mm or more and 0.12 mm or less are used and the conductor 21 is composed of a stranded wire in which the wires are not uniformly arranged, a portion where the wires and the insulator 22 are strongly adhered to each other is easily generated.

[0040] Therefore, in the present 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 refers to 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) relative to the length direction. The conductor pull-out force of 3.5 kgf / 25 mm means that the force required to pull the conductor 21 covered by the insulator 22 from the insulator 22 at a constant speed in the insulated wire 2 with 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 wire material constituting the conductor 21 can be suppressed from being closely attached to the insulator 22, and the conductor 21 can be relatively easily moved in the insulator 22. As a result, the wire breakage caused by the stress concentration on a part of the wire material as described above can be suppressed, and the resistance to bending and torsion can be improved.

[0041] The conductor pull-out force can be adjusted by adjusting the manufacturing speed (line speed) when the insulator 22 is formed by tube extrusion and the temperature of the insulator 22 just after being extruded by the tube. That is, by appropriately adjusting the manufacturing speed (line speed) when the insulator 22 is formed into a hollow cylindrical shape by tube extrusion molding and the temperature of the insulator 22 just after being extruded by the tube, the conductor pull-out force of the insulated wire 2 can be made 3.5kgf / 25mm or less. For example, if the manufacturing speed (line speed) is increased, the cooling of the resin constituting the insulator 22 becomes faster, and as a result, the close contact between the insulator 22 and the conductor 21 decreases, and the conductor pull-out force decreases. It should be noted that the conductor pull-out force of the insulated wire 2 is more preferably 3.0kgf / 25mm or less. In addition, if the conductor pull-out force of the insulated wire 2 is too small, the conductor 21 is easy to fall off from the insulator 22, so it becomes difficult to handle the insulated wire 2. Therefore, the conductor pull-out force of the insulated wire 2 is more preferably 0.5kgf / 25mm or more. That is, the conductor pull-out force of the insulated wire 2 is more preferably 0.5 kgf / 25 mm or more and 3.0 kgf / 25 mm or less. Thus, the cable 1 can be provided with improved handleability of the insulated wire 2 and improved resistance to bending and twisting.

[0042] The thickness of the insulator 22 is preferably at least twice the outer diameter of the wire used for the conductor 21. For example, the thickness of the insulator 22 is 0.16 mm to 0.30 mm. This can prevent the broken wire from piercing the insulator 22 and being exposed when the wire is broken.

[0043] When polypropylene is used as the insulator 22 , the tensile strength of the insulator 22 may be 25 MPa to 34 MPa. As described above, the tensile strength of the wire is preferably at least 450 MPa or less, and the tensile strength of the wire may be at least 20 times less than that of the insulator 22 .

[0044] However, in the present embodiment, the core assembly 3 includes two types of insulated wires 2a and 2b having different conductor cross-sectional areas and outer diameters. In this way, when the core assembly 3 includes insulated wires 2 having different conductor cross-sectional areas and outer diameters, it is expected that the resistance of each insulated wire 2 to bending and twisting is the same. This is because if one of the insulated wires 2 included in the core assembly 3 is broken, it will be judged as the life of the entire cable 1. In order to maintain the life of the entire cable 1 for a longer period of time, it is expected that the resistance of each insulated wire 2 included in the core assembly 3 to bending and twisting is the same.

[0045] In the present embodiment, the core assembly 3 includes a first insulated wire 2a and a second insulated wire 2b having a larger conductor cross-sectional area and an outer diameter than the first insulated wire 2a. In this case, in order to reduce the difference (deviation) in the resistance to bending and twisting between the first insulated wire 2a and the second insulated wire 2b (that is, to make the resistance to bending and twisting of each insulated wire 2 included in the core assembly 3 equal), the conductor pull-out force of the first insulated wire 2a may be different from the conductor pull-out force of the second insulated wire 2b within a range of 3.5kgf / 25mm or less. At this time, the conductor pull-out force of each of the plurality of first insulated wires 2a may be different from each other, and the conductor pull-out force of each of the plurality of second insulated wires 2b may be different from each other. By reducing the difference (deviation) in the resistance to bending and twisting of each insulated wire 2, the life of the entire cable 1 can be extended. Here, the life refers to a state in which the conductor 21 constituting the insulated wire 2 is judged to be broken when the cable 1 is repeatedly subjected to actions including bending and twisting. The state in which the conductor 21 is judged to be disconnected is, for example, when the resistance value increase rate of the conductor 21 constituting the cable 1 exceeds a preset value (for example, the resistance value increase rate is 20%), when all the wires constituting the conductor 21 are disconnected (all disconnected), etc. The resistance value increase rate is a ratio of how much the resistance value of the conductor 21 increases when the cable 1 is repeatedly subjected to the above-mentioned action, relative to the resistance value of the conductor 21 before the cable 1 is subjected to the above-mentioned action (initial resistance value).

[0046] In order to further reduce the difference (variation) in the resistance to bending and twisting between the first insulated wire 2a and the second insulated wire 2b, the elongation of the second insulator 22b in the second insulated wire 2b may be different from the elongation of the first insulated wire 2a in the first insulated wire 2a. This is because, in the second insulated wire 2b having a larger outer diameter than the first insulated wire 2a, the stress (tensile force on the outer side of the bend) applied to the second insulator 22b when bending becomes larger. In this case, the elongation of the first insulator 22a of each of the plurality of first insulated wires 2a may be different from each other, and the elongation of the second insulator 22b of each of the plurality of second insulated wires 2b may be different from each other. By further reducing the difference (variation) in the resistance to bending and twisting between the first insulated wire 2a and the second insulated wire 2b, the life of the entire cable 1 can be extended. More specifically, as the first insulator 22a, the value of the elongation measured using the test method based on JIS C3005 may be 790% or more. In addition, the elongation value of the second insulator 22b measured by the test method in accordance with JIS C3005 may be 810% or more. In order to further reduce the difference (deviation) in the resistance to bending and twisting between the first insulated wire 2a and the second insulated wire 2b, the difference between the elongation of the second insulator 22b in the second insulated wire 2b and the elongation of the first insulator 22a in the first insulated wire 2a may be 60% or less. It should be noted that the elongation value of each of the first insulator 22a and the second insulator 22b can be measured by the test method in accordance with JIS C3005.

[0047] (Bending Test of First Insulated Wire 2a and Second Insulated Wire 2b)

[0048] Five first insulated wires 2a and five second insulated wires 2b were produced and subjected to bending tests. The first insulated wire 2a had a first insulator 22a with a hollow cylindrical cross section formed by tube extrusion around a first conductor 21a made of a soft wire, and the second insulated wire 2b had a second insulator 22b with a hollow cylindrical cross section formed by tube extrusion around a second conductor 21b made of a soft wire. In the first insulated wire 2a, the first conductor 21a is a stranded wire (conductor cross-sectional area: 0.5 mm2) formed by stranding a plurality of wires having an outer diameter of about 0.12 mm. 2 ), the first insulator 22a is polypropylene with an elongation of 790% or more and 815% or less. In the second insulated wire 2b, the second conductor 21b is a stranded wire (conductor cross-sectional area: 1.8mm) formed by stranding a plurality of wires having an outer diameter of about 0.12mm. 2), the second insulator 22b is polypropylene with an elongation of 810% or more and 850% or less. The conductor pull-out forces of the first insulated wire 2a and the second insulated wire 2b were measured, and the results were both 0.5kgf / 25mm or more and 3.0kgf / 25mm or less.

[0049] In the bending test, Figure 2 As shown in the figure, one end of the insulated wire 2 to be the test object is fixed and a weight is hung on the other end to apply a load W of 0.3 kgf (2.94 N), and the insulated wire 2 is repeatedly bent 90 degrees to the left and right. As for the number of tests, one cycle is defined as bending 90 degrees to the right from the 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 test is repeated at a speed of 30 times per minute. The bending radius is 5 mm, and the conductor 21 is judged to be broken when all the wires are broken.

[0050] In all five first insulated wires 2a, the conductor 21 broke more than 2000 times. Moreover, the average number of bending times when the breakage occurred was more than 3000 times. In addition, in all five second insulated wires 2b, the conductor 21 broke more than 2500 times. Moreover, the average number of bending times when the breakage occurred was more than 3000 times. The above results confirm that even when using the first insulated wire 2a and the second insulated wire 2b with different conductor cross-sectional areas and outer diameters, the same bending resistance can be obtained by making the conductor pull-out force less than 3.0kgf / 25mm. Therefore, by using the insulated wire 2 with a conductor pull-out force of less than 3.0kgf / 25mm to form the collective core 3, the difference (deviation) in the resistance to bending and torsion within the collective core 3 can be reduced, thereby improving the overall resistance to bending and torsion of the cable 1.

[0051] (Variation Example)

[0052] In the above embodiment, the case where the core assembly 3 is composed of insulated wires 2a and 2b having different conductor cross-sectional areas and outer diameters is described, but the present invention is not limited thereto. Figure 3 As shown in the cable 1a, all the insulated wires 2 constituting the core assembly 3 have the same conductor cross-sectional area and outer diameter. The conductor cross-sectional area of ​​the insulated wire 2 is, for example, 0.5 mm 2 Above and 2.3mm 2 In addition, three or more insulated wires 2 having different conductor cross-sectional areas and outer diameters may be used to form the collective core 3. In this case, it is preferred that the smaller the conductor cross-sectional area of ​​the insulated wire 2, the greater the conductor pull-out force. In addition, it is preferred that the larger the outer diameter of the insulated wire 2, the greater the elongation of the insulator 22. Figure 3The cable 1a shown may be formed by twisting a plurality of twisted pair wires, each of which is formed by twisting two insulated electric wires 2, in the aggregate core 3 along the circumferential direction of the cable.

[0053] In addition, if Figure 4 As shown in the cable 1b, the core assembly 3 may also be formed by twisting a plurality of insulated wires 2 in layers. In the cable 1b, the plurality of insulated wires 2 are twisted into two layers, an inner layer 3a located on the inner side of the cable in the radial direction and an outer layer 3b located on the outer side of the cable in the radial direction, to form the core assembly 3, but the number of layers of the core assembly 3 is not limited thereto, and may be more than three layers. The conductor cross-sectional area of ​​the insulated wire 2 is, for example, 0.5 mm 2 Above and 2.3mm 2 Below. Figure 4 In the cable 1b shown, both the inner layer 3a and the outer layer 3b of the collective core 3 can be formed by twisting a plurality of twisted pairs of two insulated electric wires 2 together in the circumferential direction of the cable.

[0054] When the core assembly 3 is composed of two layers as in the cable 1b, it is preferred that a contact prevention member 7 is provided between the inner layer 3a and the outer layer 3b to prevent the insulated wires 2 constituting the inner layer 3a from contacting the insulated wires 2 constituting the outer layer 3b. Thus, when the cable 1 is repeatedly bent or twisted, repeated friction between the insulated wires 2 constituting the inner layer 3a and the insulated wires 2 constituting the outer layer 3b can be suppressed, and resistance to bending and twisting can be improved.

[0055] In the present embodiment, the contact prevention member 7 is composed of a fibrous spacer 6, but the contact prevention member 7 may also be composed of a belt member having a buffering property wound around the inner layer 3a. By using a belt member having a buffering property as the contact prevention member 7, the contact between the inner layer 3a and the outer layer 3b can be reliably suppressed, and the distance between the inner layer 3a and the outer layer 3b can be reduced compared to the case of using a fibrous spacer 6. Therefore, the diameter of the cable 1 can be reduced, and the wear of the insulator 22 caused by the friction between the belt member and the insulated wire 2 can be suppressed. As a belt member having a buffering property, for example, a resin belt (polyethylene belt, polypropylene belt, etc.) having a plurality of bubbles can be used.

[0056] In the cable 1b, the case where all the insulated wires 2 constituting the aggregate core 3 have the same structure has been described, but it is also possible to Figure 5 As shown in the cable 1c, the core assembly 3 includes insulated wires 2 with different conductor cross-sectional areas and outer diameters. In the cable 1c, the inner layer 3a is composed of 6 first insulated wires 2a with smaller conductor cross-sectional areas and outer diameters, and the outer layer 3b is composed of 12 second insulated wires 2b with larger conductor cross-sectional areas and outer diameters 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 Above and less than 0.8mm2 The conductor cross-sectional area of ​​the second insulated wire 2b constituting the outer layer 3b is, for example, 1.0 mm 2 Above and less than 2.3mm 2 . In the inner layer 3a, a plurality of first insulated wires 2a are arranged in contact with each other along the circumference of the cable or in a state separated by a spacer 6. In addition, in the outer layer 3b, a plurality of second insulated wires 2b are arranged in contact with each other along the circumference of the cable or in a state separated by a spacer 6. In this way, when insulated wires 2 with different conductor cross-sectional areas and outer diameters are used for the collective core 3, by arranging the first insulated wires 2a with relatively small mechanical strength (insulated wires 2 with small conductor cross-sectional area and outer diameter) in the inner layer 3a, the resistance to bending and torsion can be further improved. Figure 5 In the cable 1c shown, the inner layer 3a of the collective core 3 can also be composed of a plurality of twisted pair wires formed by twisting every two first insulated wires 2a together, and the outer layer 3a of the collective core 3 is composed of a plurality of twisted pair wires formed by twisting every two second insulated wires 2b together, and twisted along the circumference of the cable.

[0057] (Functions and Effects of Implementation Methods)

[0058] As described above, in the cable 1 of this embodiment, the insulator 22 of the insulated wire 2 constituting the collective core 3 is made of non-fluororesin, and for the insulated wire 2, the force when the conductor 21 is pulled out from the insulator 22 relative to the length direction, that is, the conductor pulling force is less than 3.5kgf / 25mm.

[0059] By making the conductor pull-out force 3.5 kgf / 25 mm or less, the conductor 21 can be easily moved in the insulator 22, and even when the insulator 22 is made of non-fluorine resin, high resistance to bending and twisting can be achieved in each insulated wire 2. As a result, it is possible to achieve a cable 1 that can reduce environmental load and is not easily degraded even when bending and other actions are repeatedly applied. At this time, it is preferable that the elongation of the insulator 22 is 500% or more, thereby easily suppressing the wire breakage of the conductor 21 caused by the friction between the insulator 22 and the conductor 21. In addition, in the cable 1 of the present embodiment, since the conductor pull-out force is 3.5 kgf / 25 mm or less, the conductor 21 becomes easy to move in the insulator 22, so the terminal end of the insulated wire 2 is easy to bend, and the stripping process of the insulator 22 is also easy. Therefore, in order to improve the performance and function of a device such as a robot, even if the number of insulated wires 2 constituting the cable 1 is increased, it is easy to connect the terminal ends of a plurality of insulated wires 2 to one connector. Furthermore, when the terminal of the cable 1 is connected to the connector, the connection work is easy even if the interval between the adjacent insulated wires 2 is set to a distance such that the insulators 22 are in contact with each other.

[0060] (Summary of Implementation Methods)

[0061] Next, the technical ideas grasped from the above-described embodiments are described by referring to the reference numerals in the embodiments. However, the reference numerals in the following description do not limit the constituent elements in the claims to the members specifically shown in the embodiments.

[0062] [1] A cable (1) comprising a core assembly (3) formed by twisting a plurality of insulated wires (2) and a sheath (5) covering the core assembly (3), wherein the insulated wire (2) has a conductor (21) composed of a plurality of wires and an insulator (22) covering the conductor (21), wherein the insulator (22) is made of a non-fluorine resin, and wherein the force applied when the conductor (21) is pulled out from the insulator (22) in the longitudinal direction of the insulated wire (2), i.e., the conductor pull-out force, is not more than 3.5 kgf / 25 mm.

[0063] [2] The cable (1) according to [1], wherein the conductor (21) is composed of a stranded wire formed by twisting a plurality of the wires together, and the plurality of the wires are composed of soft copper wires or soft copper alloys having an outer diameter of not less than 0.08 mm and not more than 0.12 mm.

[0064] [3] The cable (1) according to [2], wherein the tensile strength of the wire material constituting the conductor (21) is less than 20 times the tensile strength of the insulator.

[0065] [4] The cable (1) according to [3], wherein the plurality of wires constituting the conductor (21) are composed 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.

[0066] [5] The cable (1) according to any one of [1] to [3], wherein the cross-sectional area of ​​the conductor (21) is 0.2 mm 2 Above and 2.5mm 2 the following.

[0067] [6] The cable (1) according to any one of [1] to [5], wherein the insulator (22) is made of an olefin-based resin.

[0068] [7] The cable (1) according to any one of [1] to [6], wherein the elongation of the insulator (22) is 500% or more.

[0069] [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 material used for the conductor (21).

[0070] [9] The cable (1b, 1c) according to any one of [1] to [8], wherein the aggregate core (3) is formed by twisting a plurality of the insulated electric wires (2) in layers.

[0071]

[10] The cable (1b, 1c) according to [9], wherein in the collective core (3), an anti-contact component (7) is provided between an inner layer (3a) located on the inner side in the radial direction of the cable and an outer layer (3b) located on the outer side in the radial direction of the cable to prevent the insulated wire (2) constituting the inner layer (3a) from contacting the insulated wire (2) constituting the outer layer (3b).

[0072]

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

[10] , wherein the contact prevention member (7) is composed of a tape member having a cushioning property wound around the inner layer (3a).

[0073] (Note)

[0074] The embodiments of the present invention have been described above, but the embodiments described above do not limit the invention involved in the claims. In addition, it should be noted that all combinations of features described in the embodiments are not limited to the means necessary for solving the problems of the invention. In addition, the present invention can be implemented by appropriately deforming within the scope of its main purpose.

Claims

1. A cable comprising a core assembly formed by twisting a plurality of insulated electric wires and a sheath covering the core assembly, The insulated wire includes a conductor composed of a plurality of wires and an insulator covering the conductor. The insulator is made of non-fluorine resin, In the insulated wire, a conductor pulling force, which is a force when the conductor is pulled out from the insulator in a longitudinal direction, is 3.5 kgf / 25 mm or less.

2. The cable according to claim 1, wherein The conductor is composed of a plurality of stranded wires twisted together. The plurality of wires are made of soft copper wire or soft copper alloy having an outer diameter of 0.08 mm to 0.12 mm.

3. The cable according to claim 2, wherein: The tensile strength of the wire material constituting the conductor is less than 20 times the tensile strength of the insulator.

4. The cable according to claim 3, wherein: The plurality of wires constituting the conductor are formed of 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 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.

5. The cable according to claim 1, wherein The cross-sectional area of ​​the conductor is 0.2 mm 2 Above and 2.5mm 2 the following.

6. The cable according to claim 1, wherein The insulator is made of olefin resin.

7. The cable according to claim 1, wherein The elongation of the insulator is greater than 500%.

8. The cable according to claim 1, wherein The thickness of the insulator of the insulated wire is at least twice the outer diameter of the wire material used for the conductor.

9. The cable according to claim 1, wherein: The aggregate core is formed by twisting a plurality of the insulated electric wires in layers.

10. The cable according to claim 9, wherein In the aggregate core, a contact prevention member is provided between an inner layer located radially inwardly of the cable and an outer layer located radially outwardly of the cable to prevent the insulated wires constituting the inner layer from contacting the insulated wires constituting the outer layer.

11. The cable according to claim 10, wherein The contact prevention member is composed of a belt member having a cushioning property and wound around the inner layer.

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