Multi-core cable

Abstract

To provide a multicore cable of which twisting resistance was improved.SOLUTION: A multi-core cable comprising at least a central member and a plurality of conductors arranged around the central member, wherein in the multicore cable obtained by collectively twisting the central member and the conductors, the central member consists of an interposition or a tube, and the conductors are characterized by having a triple-twisted structure (parent-twisted) in which collective twisted strands (child-twisted) obtained by twisting a plurality of strands are further twisted into three bundles.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cable primarily used in industrial robots, and particularly to a multi-core cable that is suitable for use in moving parts that require complex movements depending on the position and number of joints, and that is primarily excellent in terms of twisting resistance. [Background technology]

[0002] Many multi-core cables with excellent twist resistance have been known. For example, Patent Document 1 discloses a cable in which the tensile yield stress of the sheath member is set to a specified value and the twisting direction of the assembly is the same as the winding direction of the tape member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-204591 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a multi-core cable with improved twist resistance. [Means for solving the problem]

[0005] (1) A multi-core cable consisting of at least a central member and a plurality of conductors arranged around the central member, and in which the central member and the conductors are twisted together, characterized in that the central member is made of an insert or a tube, and the conductors have a three-strand (parent twist) structure in which three bundled strands (child strands) of stranded wires (child strands) are further twisted together, each strand being made by twisting together a plurality of strands. (2) It is preferable that the twisting direction of the bunched strands (child strands) of the conductor is opposite to the twisting direction of the three strands (parent strands). (3) It is preferable that at least one of the conductors has a slip material applied to its periphery. [Effects of the Invention]

[0006] According to the present invention, the load on the conductor due to twisting is reduced, thereby reducing defects such as wire breakage and improving twisting resistance. [Brief explanation of the drawings]

[0007] [Figure 1] 1(a), (b), and (c) show examples of cross-sectional views of a multi-core cable according to the present invention. [Figure 2] 3 shows another example of a cross-sectional view of the multi-core cable of the present invention. [Figure 3] 1 is a schematic diagram showing a torsion resistance test method according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

[0008] The basic structure of an example of a multi-core cable 1 of the present invention will be described below with reference to the drawings.

[0009] Figure 1(a) shows a multi-core cable 1 that is composed of at least a central member 2 and multiple conductors 3 arranged around the central member 2, and in which the central member 2 and conductors 3 are twisted together. The central member 2 is made of an insert or a tube, and the conductors 3 have a three-strand (parent twist) structure in which three bundled strands (child strands 3a) made of multiple strands twisted together are further twisted together.

[0010] Here, for the conductor 3, a bunched strand formed by twisting together multiple wires is called a "child strand," and a triple strand formed by bundling and twisting three child strands together is called a "parent strand." A feature of the present invention is that the conductor 3 has a triple-strand parent strand structure.

[0011] Furthermore, from the viewpoint of improving twist resistance, it is preferable that the twist direction of the bunched strand (child twists 3a) and the direction of the three-strand twist (parent twist) are opposite to each other. Although not particularly limited, a configuration in which the child twist is Z-twisted and the parent twist is S-twisted is commonly used.

[0012] The outer diameter of the conductor 3 is not limited, but is preferably 0.6 to 7.0 mm, and more preferably 2.0 to 4.0 mm from the viewpoint of flexibility. The diameter of the strands of the child strands is preferably 0.05 to 0.18 mm, and more preferably 0.08 to 0.10 mm. 30 to 230 of these strands are twisted together to form a bunched strand (child strand), and three child strands are further bundled together to form a parent strand. The number of wires in the child strand is more preferably 50 to 150.

[0013] It is preferable that the outer diameters of the conductors 3 are all approximately the same. Here, "same" means that errors that may occur during manufacturing are allowed, and that the diameters are the same within ±10% of the center value of the dimension.

[0014] The outer diameter of the conductor 3 is preferably 0.90 to 1.0 in terms of flatness (minimum outer diameter / maximum outer diameter). This results in point contact between the conductors 3, reducing friction. A ratio of 0.95 to 1.0 is more preferred.

[0015] The twist pitch of the conductor 3 is not limited, but is preferably set to be relatively long from the viewpoint of twist resistance.

[0016] The material of the conductor 3 is not limited, but examples thereof include a metal wire such as copper or aluminum, or an alloy wire made of these metals with added iron, zinc, nickel, etc. The surface of the metal wire may be plated with silver, tin, etc.

[0017] It is preferable that at least one of the conductors 3 is provided with a sliding material 5 around its periphery. As shown in Fig. 1(b), it is preferable that the sliding material 5 is provided on all of the conductors 3, but as shown in Fig. 1(c), some conductors may not be provided with the sliding material 5. In that case, from the viewpoint of improving bending resistance, it is preferable that the conductors with and without the sliding material 5 be arranged alternately.

[0018] The material of the sliding member 5 is not limited, but is preferably a fluororesin such as PTFE, PFA, FEP, or ETFE, with PTFE being particularly preferred.

[0019] The structure of the sliding material 5 is not limited, and examples include a tubular covering by extrusion molding and tape wrapping. Tape wrapping is particularly preferred from the viewpoint of flexibility. The winding direction of the tape is not limited, but it is preferably the opposite direction to the twisting direction of the parent strand of the conductor. The winding pitch of the tape is not limited, but is preferably 1 / 8 to 1 / 2.

[0020] The central member 2 is characterized in that it consists of a tube or insert.

[0021] The material of the intervening core member 2 is not limited, but examples include plastic materials such as polyester and nylon, and thread-like, string-like, and rod-like materials made of cotton.

[0022] The material of the tube of the central member 2 is also not limited and may be a thermoplastic resin or a thermoplastic elastomer, but polyurethane and polyvinyl chloride are preferred in terms of flexibility and versatility. Fluororesins such as PTFE, PFA, FEP, and ETFE are preferred in terms of excellent slip properties.

[0023] The central member 2 is preferably provided with a sliding material 5 around its periphery (see Figs. 1(b) and (c)). Examples include a tubular covering by extrusion molding or tape wrapping, but from the viewpoint of flexibility, tape wrapping is preferred, and the wrapping direction is preferably the same as the tape wrapping applied to the conductor 3. As mentioned above, the material of the sliding material 5 is preferably a fluororesin, and particularly preferably PTFE. The pitch of the tape wrapping is not limited, but is preferably 1 / 8 to 1 / 2.

[0024] Furthermore, when six or more conductors 3 are used, it is preferable that the outer diameters of the central member 2 and the conductors 3 are approximately the same. By making all of them approximately the same outer diameter, local loads are less likely to be applied, which contributes to improving twisting resistance.

[0025] Depending on requirements, some of the multiple conductors 3 may be replaced with other electric wires or cables (coaxial cables, multi-core cables, optical fiber cables, etc.), tubes, fillers, etc.

[0026] Regarding the arrangement of the conductor 3, Materials At least one layer is disposed around the center of the Materials The same layer and multiple layers are applied with 2 at the center. Figure 1 shows an example of one layer, and Figure 2 shows an example of two layers. From the viewpoint of twisting resistance, a structure consisting of only one layer (Figure 1) is preferable.

[0027] Here, the term "total twist" refers to the state in which the core member 2 and conductors 3 of the multi-core cable 1 are twisted together. The direction of the total twist is not limited, but it is preferable that it be the same as the direction of the three-strand twist (parent twist) of the conductors 3, and most preferably, both the total twist and the parent twist are S-direction. The pitch of the total twist is not limited, but it is preferable that it be set longer from the viewpoint of twist resistance.

[0028] After the total twisting, an outer layer 4 is applied. The material is preferably polyvinyl chloride, polyurethane, etc. The thickness is preferably φ1.0 to 4.0 mm, and the outer diameter is preferably φ10 to 30 mm.

[0029] A sliding material 5 is provided between the fully twisted core wire S and the outer layer 4 as appropriate (see Fig. 1(b)(c)). The structure of the sliding material 5 is preferably tape-wound from the viewpoint of flexibility. The tape winding direction is preferably the same as the twisting direction of the fully twisted wire from the viewpoint of twist resistance. As mentioned above, the material of the sliding material 5 is preferably fluororesin, and particularly preferably PTFE. The tape winding pitch is not limited, but is preferably 1 / 8 to 1 / 2.

[0030] The multi-core cable 1 of the present invention has excellent twist resistance, and is therefore suitable for use in moving parts of industrial robots that are required to perform complex movements depending on the positions and number of joints. There are no particular limitations on the use, but it is preferably used for large currents and / or welding. [Example]

[0031] The multi-core cable 1 of the present invention will be specifically described below by way of examples, but is not limited to these.

[0032] Example 1 In the multi-core cable 1 shown in Figure 2, the core member 2 is made of cotton and is wrapped in PTFE tape (Z-twist) as the sliding material 5. Two conductors 3 are arranged in the same layer around the core member 2. The conductors 3 are made of a three-strand (parent twist) bunched strand (child twist) consisting of 201 0.10 mm diameter strands twisted together, and are tin-plated annealed copper wires with an outer diameter of approximately 3.5 mm. The child twist of the conductors 3 is Z-twisted, and the parent twist is S-twisted. All conductors 3 are wrapped in PTFE tape (Z-twist) as the sliding material 5. The core member 2 and conductors 3 are twisted together in the S direction, and are further wrapped in PTFE tape (S-twist) as the sliding material 5. The outer layer is 2.0 mm thick PVC, and the outer diameter of the multi-core cable 1 is approximately 23.0 mm.

[0033] Example 2 This is a multi-core cable 1 in which the sliding material 5 is applied to only half of the conductors 3 in Example 1. The conductors with and without the sliding material 5 are arranged alternately.

[0034] (Comparative Example) This is a structure in which the number of conductor strands is seven in Example 1. Specifically, this structure has seven strands (parent strands) twisted together (child strands) made up of 135 strands of 0.08 mm diameter wires, and the outer diameter is approximately 3.5 mm, the same as Example 1.

[0035] The cables of the above examples and comparative examples were subjected to a twist resistance test, and the results of the rate of increase in the resistance value of the conductor and the rate of disconnection are shown in Table 1.

[0036] (Twist resistance test method) A schematic diagram showing the bending test method is shown in FIG. The measurement conditions were: sample length 800 mm, fixation distance 210 mm, load 1500 gf. As shown in the figure, twisting the sample end 180 degrees left and right is counted as one twist, and after twisting a certain number of times at a test speed of 60 times per minute, the resistance of the conductor was measured. The increase in resistance (%) compared to the resistance before the test is shown in Table 1.

[0037] [Table 1]

[0038] In the torsion resistance test, Examples 1 and 2 showed low resistance increase rates and low disconnection rates after 900,000 cycles, demonstrating superior torsion resistance compared to the comparative example. Materials 2nd grade Beauty Example 1, which has a structure in which the sliding material 5 is applied to the entire conductor 3, is particularly excellent in terms of resistance to twisting. [Industrial Applicability]

[0039] The cable of the present invention has excellent twist resistance and is therefore useful for industrial robots, and can be used for a variety of purposes, including, but not limited to, a power cable for large currents, a welding cable, and an equipment cable. [Explanation of symbols]

[0040] 1 multi-core cable 2. Central member 3 Conductors 3a stranded wire (child twist) 4 Outer layer 5. Slippery material S Fully twisted core wire

Claims

1. A multi-core cable comprising at least a central member and a plurality of conductors arranged around the central member, and in which the central member and the conductors are twisted together, The central member comprises a tube or insert with a sliding member disposed around the periphery thereof; The conductor has a three-strand (parent twist) structure in which three bundled strands (child twists) of stranded wires (child twists) are further bundled and twisted together, and At least one of the conductors is wrapped with a slippery tape, and the plurality of conductors have approximately the same outer diameter as the central member.

2. The twisting direction of the bunched strands (child strands) of the conductor is opposite to the twisting direction of the three strands (parent strands). The multi-core cable according to claim 1 .

3. The direction of the three strands (parent strands) of the conductor and the winding direction of the tape are opposite to each other.

3. The multi-core cable according to claim 1 or 2.

4. The conductor is arranged in a plurality of layers around the central member in the same layer. The multi-core cable according to any one of claims 1 to 3.

5. The direction of the three strands (parent strands) of the conductor is the same as the direction in which the core member and the conductors are twisted together. The multi-core cable according to any one of claims 1 to 4.

6. Characterized in that it is used for large currents and / or welding. The multi-core cable according to any one of claims 1 to 5.

Images