Cable

Abstract

The invention provides a cable which generates little smoke, is difficult to burn and has a small outer diameter. A cable (1) is provided with an integrated core (4) comprising a plurality of electric wires (2), and a cladding layer (7) covering the periphery of the integrated core (4) and constituting the outermost layer, the cladding layer (7) comprising a soot generation suppression layer conforming to level 1 in the cleanliness level according to ISO 14644-1, and a combustion suppression layer (6) having an oxygen index greater than the oxygen index of the cladding layer (7) by 5 or more is provided between the cladding layer (7) and the integrated core (4).

Description

Technical Field

[0001] This invention relates to cables. Background Technology

[0002] Conventionally, cables used for wiring in devices such as industrial robots have included, for example, cables with a core consisting of multiple wires (insulated wires, twisted pairs of insulated wires twisted together) and a sheath covering the core (see, for example, Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

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

[0006] The problem that the invention aims to solve

[0007] For cables used in industrial robots, machine tools, or in clean environments such as semiconductor manufacturing facilities, there is a requirement for cables that, in addition to excellent abrasion and bending resistance, produce little smoke and are not easily flammable. In particular, for the outermost sheath of the cable, it is desirable to have a sheath that suppresses dust generation caused by surface friction from contact with other components (i.e., a sheath that produces little smoke).

[0008] On the other hand, in order to improve the functionality of devices such as industrial robots, there is a tendency to increase the number of wires in cables. However, due to the increase in the number of wires, the proportion of combustible materials in the cable also increases, sometimes making the cable more flammable. Therefore, it is also desirable to make the sheath less flammable.

[0009] However, if the amount of flame retardant added is increased to make the sheath less flammable, smoke and dust can easily be generated when the sheath rubs against other components. To make the sheath less flammable without increasing the amount of flame retardant added, one could consider increasing the thickness of the sheath, but in this case, the cable outer diameter becomes larger, making wiring more difficult.

[0010] Therefore, the purpose of this invention is to provide a cable that produces less smoke and dust, is difficult to burn, and has a small outer diameter.

[0011] Methods for solving problems

[0012] To address the aforementioned issues, this invention provides a cable comprising a core composed of multiple wires and an outermost sheath covering the core. The sheath is composed of a smoke-generating suppression layer that meets the cleanliness level 1 according to ISO 14644-1. A combustion-inhibiting layer is provided between the sheath and the core, the combustion-inhibiting layer having an oxygen index that is 5 or more greater than that of the sheath.

[0013] Invention Effects

[0014] According to the present invention, it is possible to provide a cable that produces less smoke and dust, is difficult to burn, and has a small outer diameter. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of a cable perpendicular to its length direction according to one embodiment of the present invention.

[0016] Figure 2 In the diagram, (a) and (b) are cross-sectional views showing the cross-section of a cable perpendicular to its length direction according to other embodiments of the present invention.

[0017] Figure 3 This is a cross-sectional view showing a cable with its cross-section perpendicular to the length direction according to another embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures

[0019] 1…Cable, 2…Wire, 2a…Insulated wire, 3…Fiber medium, 4…Collective core, 5…Press-wound tape, 6…Flame-inhibiting layer, 7…Covering layer, 8…Shielding layer, 21…Conductor, 22…Insulator, 81…Conductive tape, 82…Shielded wire. Detailed Implementation

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

[0021] (Overall structure of cable 1)

[0022] Figure 1 This is a cross-sectional view showing the cable 1 of this embodiment, perpendicular to its length. The cable 1 is used, for example, in devices such as industrial robots, machine tools, or semiconductor manufacturing equipment, and in clean environments where the generation of fumes is undesirable.

[0023] like Figure 1As shown, the cable 1 includes a core 4 composed of multiple wires 2 and an outermost sheath 7 covering the core 4. In this embodiment, a pressing and winding tape 5 is provided around the core 4, a flame-suppressing layer 6 is provided covering the area around the pressing and winding tape 5, and the sheath 7 is provided covering the area around the flame-suppressing layer 6. Each layer will be described in detail below.

[0024] (Wire 2)

[0025] The wire 2 is an insulated wire 2a consisting of a conductor 21 and an insulator 22 surrounding the conductor 21. However, it is not limited to this; the wire 2 can also be a coaxial cable with a shielding layer and an outer sheath sequentially provided around the insulator 22, or a twisted pair of insulated wires 2a twisted together. The conductor 21 is constructed by twisting together multiple metal wires made of copper or copper alloy. The metal wires may also be plated with tin, silver, or the like. In this embodiment, tin-plated soft copper wire with an outer diameter of 0.1 mm or less is used to construct the conductor 21. The outer diameter of the conductor 21 is, for example, 1.0 mm or less.

[0026] The insulator 22 is provided to cover the periphery of the conductor 21, for example, by tube extrusion. The thickness of the insulator 22 is, for example, 0.1 mm or more and 0.4 mm or less. In addition, the outer diameter of the insulator 22, that is, the outer diameter of the wire 2, is, for example, 0.7 mm or more and 3.0 mm or less.

[0027] As the insulator 22, fluoropolymers such as ETFE (ethylene-tetrafluoroethylene copolymer) or non-fluoropolymers can be used. In recent years, the use of fluoropolymers has been controlled to suppress environmental impact; from the viewpoint of suppressing environmental impact, non-fluoropolymers are arguably more preferable. Furthermore, the specific gravity of the insulator 22 is more preferably 1.0 or less. This makes the wire 2 lighter, reducing the weight of the cable 1, and thus further suppressing the generation of dust due to friction between the cable 1 and surrounding components. As the non-fluoropolymer with a specific gravity of 1.0 or less, PP (polypropylene) or irradiated cross-linked PP is preferred.

[0028] (Core 4)

[0029] In this embodiment, the core 4 is constructed by twisting six insulated wires 2a together with a fiber interlayer 3. The six insulated wires 2a are arranged in a circumferential direction of the cable, and adjacent insulated wires 2a in the circumferential direction are configured to not be in direct contact by interlocking with the fiber interlayer 3. The fiber interlayer 3 can be, for example, a fibrous interlayer made of staple fiber yarn, nylon, etc. The fiber interlayer 3 is disposed at the center of the cable 1. In addition, the fiber interlayer 3 can also fill between adjacent wires 2 in the circumferential direction and between the wires 2 and the press-wrap tape 5.

[0030] Here, multiple (6) insulated wires 2a are twisted together to form the core 4, but this is not the only possibility. For example, multiple twisted pairs of wires 2a can also be twisted together to form the core 4. Alternatively, multiple sub-twisted wires 2a can be twisted together to form the core 4. Furthermore, the core 4 may also include a wire-like body or tube made of resin. For example, multiple wires 2 can be twisted around a wire-like body disposed at the center of the cable to form the core 4.

[0031] (Press the winding belt 5)

[0032] The press-wound tape 5 is spirally wound around the core 4. For example, the press-wound tape 5 can be a resin tape made of non-foaming resin such as PE (polyethylene), PP, PVC (polyvinyl chloride), a foamed resin tape made of foaming resin such as foamed PP, non-woven fabric, Japanese paper, etc.

[0033] (Combustion suppression layer 6 and coating layer 7)

[0034] In the cable 1 of this embodiment, a flame-inhibiting layer 6 is provided to cover the periphery of the pressing and winding tape 5, and a sheathing layer 7 is provided to cover the periphery of the flame-inhibiting layer 6. In the cable 1, the outermost sheathing layer 7 and the flame-inhibiting layer 6 are provided in direct contact. For example, if a large amount of flame retardant is added to the sheathing layer 7 to improve its flame retardancy, the flame retardant, being a powdered filler, is prone to generating smoke. As in this embodiment, by providing a flame-inhibiting layer 6, which contains more flame retardant than the sheathing layer 7 and has a higher flame retardancy than the sheathing layer 7, as a different layer from the sheathing layer 7 and located further inside the sheathing layer 7, the overall flame retardancy of the cable 1 can be improved, and the amount of flame retardant added to the sheathing layer 7 can be suppressed to inhibit smoke generation.

[0035] A flame-inhibiting layer 6 is disposed between the covering layer 7 and the core 4. The flame-inhibiting layer 6 is formed by extruding a resin composition with a higher flame retardancy than the covering layer 7 through insert extrusion or tube extrusion, or by winding a flame-retardant tape member. Here, as the flame-inhibiting layer 6, a resin composition based on polyvinyl chloride resin and containing more flame retardant than the covering layer 7 is used. For example, flame retardants containing antimony trioxide, aluminum hydroxide, magnesium hydroxide, phosphorus, etc., can be used.

[0036] The coating layer 7 functions as a smoke-generating suppression layer that meets the cleanliness level 1 according to ISO 14644-1, and is formed from a resin composition based on polyvinyl chloride resin. To suppress smoke generation, the amount of flame retardant added to the coating layer 7 is adjusted to be sufficiently less than that of the combustion-suppressing layer 6. As the flame retardant, similar to that used in the combustion-suppressing layer 6, for example, flame retardants containing antimony trioxide, aluminum hydroxide, magnesium hydroxide, phosphorus, etc., can be used.

[0037] As described above, in the sheathing layer 7, to suppress smoke generation, it is preferable to reduce the amount of flame retardant added, thus lowering the oxygen index (the minimum oxygen concentration required for sustained combustion of the material). On the other hand, to improve the flame retardancy of the cable 1, it is desirable for the combustion inhibition layer 6 to have a high oxygen concentration. In the cable of this embodiment, the combustion inhibition layer 6 has an oxygen index that is 5 or more greater than that of the sheathing layer 7. More preferably, the difference between the oxygen index of the sheathing layer 7 and the oxygen index of the combustion inhibition layer 6 is 7 or more and 15 or less. More specifically, it is preferable that the oxygen index of the combustion inhibition layer 6 is 30 or more and the oxygen index of the sheathing layer 7 is 25 or less. Thus, a cable 1 that balances flame retardancy and low smoke generation is obtained. It should be noted that the oxygen index can be measured using an oxygen index testing machine according to the test method of JIS K7201-2.

[0038] Furthermore, the mass of the sheathing layer 7 per unit length of the cable (hereinafter referred to as the weight per unit length of the sheathing layer 7 (kg / km)) can be greater than the mass of the combustion-inhibiting layer 6 per unit length of the cable (hereinafter referred to as the weight per unit length of the combustion-inhibiting layer 6). More specifically, the weight per unit length of the sheathing layer 7 can be more than 1.5 times and less than 6.5 times the weight per unit length of the combustion-inhibiting layer 6. This is because if the weight per unit length of the sheathing layer 7 is less than 1.5 times the weight per unit length of the combustion-inhibiting layer 6, the sheathing layer 7 becomes thinner and cannot adequately suppress smoke generation, and the mechanical strength of the sheathing layer 7 decreases, making it more prone to damage. Conversely, if the weight per unit length of the sheathing layer 7 exceeds 6.5 times the weight per unit length of the combustion-inhibiting layer 6, the combustion-inhibiting layer 6 becomes thinner, and its flame retardancy decreases. For the same reason, the thickness of the combustion-inhibiting layer 6 can be more than 20% and less than 65% of the thickness of the sheathing layer 7. In this embodiment, the thickness of the combustion suppression layer 6 is set to be 0.2 mm or more and 0.5 mm or less, and the thickness of the covering layer 7 is set to be 0.8 mm or more and 1.0 mm or less.

[0039] Although not shown in the figure, the cable 1 may also have a shielding layer made of braided shielding or the like. The shielding layer may be disposed between the covering layer 7 and the flame-suppressing layer 6, or between the flame-suppressing layer 6 and the press-wound tape 5.

[0040] (Smoke and dust generation test)

[0041] A dust generation test was conducted on cable 1. The dust generation test involved placing cable 1 within a cable drag chain (registered trademark) and applying a U-shaped bending motion to the cable drag chain (registered trademark). This involved fixing one end of the cable in a U-shaped position and repeatedly sliding the other end along the cable's length. A particle counter was used to measure the particles generated during this motion. The movable velocity v and acceleration / deceleration a during the U-shaped bending motion were set to the following three conditions:

[0042] Condition 1: v = 0.5 m / s, a = 1.0 m / s 2

[0043] Condition 2: v = 1.0 m / s, a = 2.0 m / s 2

[0044] Condition 3: v = 2.0 m / s, a = 5.0 m / s 2

[0045] Smoke and dust generation tests were conducted on three types of cables with different outer diameters. The test results are summarized in Table 1.

[0046] [Table 1]

[0047]

[0048] Smoke generation tests were conducted on three types of cables with different outer diameters, masses, and densities (weight per unit volume) as shown in Table 1. As density (weight per unit volume), kinetic velocity (v), and acceleration / deceleration (a) increase, the conditions for smoke generation become more stringent; however, under any condition, compliance with Class 1 of the cleanliness standards according to ISO 14644-1 was confirmed. Furthermore, the qualification condition for Class 1 of the cleanliness standards according to ISO 14644-1 is that particles with a diameter of 0.1 μm are present in a concentration of 1 μm. 3 The number is 10 or less.

[0049] (Flame retardant test)

[0050] In addition, for cable 1, a VW-1 test and a cable flame test according to UL1581 were performed. The outer diameter of cable 1 was set to approximately 6.0 mm, and fluoropolymer (ETFE) was used as the insulation 22 for wire 2. Furthermore, in the flame retardancy test, Example 1, in which a shielding layer was provided between the sheathing layer 7 and the combustion-inhibiting layer 6, and Example 2, in which a shielding layer was provided between the combustion-inhibiting layer 6 and the press-wound tape 5, were tested. The shielding layer in Examples 1 and 2 was an interwoven braided shielding material using tinned soft copper wire and fiber wire (short fiber wire). For comparison, a comparative example cable omitting the combustion-inhibiting layer 6 was also subjected to the same flame retardancy test as Examples 1 and 2. The results of the flame retardancy test showed that in both Examples 1 and 2, the VW-1 test and the cable flame test were both passed. The inventors conducted research and concluded that if the combustion inhibition layer 6 starts to burn after the cladding layer 7 burns, non-combustible gas is generated from the combustion inhibition layer 6. The spread of combustion in the cladding layer 7 is suppressed by the non-combustible gas and the endothermic reaction during its generation. On the other hand, in a comparative example where the combustion inhibition layer 6 was omitted, both the VW-1 test and the cable flame test failed.

[0051] (The role and effect of the implementation method)

[0052] As explained above, in the cable 1 of this embodiment, the sheathing layer 7 is composed of a smoke-generating suppression layer that meets the cleanliness level 1 according to ISO 14644-1, and a combustion-inhibiting layer 6 with an oxygen index 5 or more greater than that of the sheathing layer 7 is provided between the sheathing layer 7 and the core 4. Therefore, a cable 1 that suppresses smoke generation and improves flame retardancy can be obtained. Furthermore, by providing the combustion-inhibiting layer 6, it is not necessary to thicken the sheathing layer 7, and the increase in the diameter of the cable 1 can also be prevented.

[0053] (Other implementation methods)

[0054] Figure 2 The cable 1a shown in (a) is essentially the same as Figure 1 The cable has the same structure as the cable 1, but it differs in that three twisted pairs 23 are twisted together to form a core 4 and in that a shielding layer 8 is provided between the combustion suppression layer 6 and the core 4 (between the combustion suppression layer 6 and the press-wrap tape 5).

[0055] Preferably, the twisting direction of the twisted pair 23 is the same as the twisting direction of the connecting core 4. This suppresses the load applied to the wire 2 during bending and other actions, improving its resistance to bending and other actions. It should be noted that the twisting direction of the twisted pair 23 refers to the direction in which the wire 2 rotates from one end to the other when viewed from one end of the twisted pair 23. Similarly, the twisting direction of the connecting core 4 refers to the direction in which the twisted pair 23 rotates from one end to the other when viewed from one end of the cable 1.

[0056] In cable 1a, the shielding layer 8 is composed of a braided shield. For the purpose of reducing the weight of cable 1, the shielding layer 8 can be composed of an interwoven braided shield consisting of multiple metal wires (e.g., tinned soft copper wire) and multiple fiber wires (e.g., short fiber wire), or a braided shield consisting of metal foil wires (e.g., copper foil wire) with metal foil wound around the fiber filaments. This makes cable 1 lighter and further suppresses dust generated by friction with surrounding components.

[0057] In cable 1a, a shielding layer 8 is provided between the flame-suppressing layer 6 and the core 4, with the flame-suppressing layer 6 in contact with the sheathing layer 7. Therefore, when cable 1a burns (i.e., when the outermost sheathing layer 7 burns), combustion gases are easily generated from the flame-suppressing layer 6, which serves as the base layer of the sheathing layer 7, further improving the flame-retardant effect. Furthermore, by forming the flame-suppressing layer 6 as far outward as possible in the radial direction of the cable (i.e., close to the sheathing layer 7), even with the same thickness, the weight per unit length can be increased, further enhancing the flame-suppressing effect of the sheathing layer 7.

[0058] Figure 2 Cable 1b shown in (b) is in Figure 2 In cable 1a of (a), a shielding layer 8 is provided between the sheathing layer 7 and the flame-suppressing layer 6. The shielding layer 8 and... Figure 2 Similarly, cable 1a of (a) can be constructed from an interwoven braided shield or a braided shield made of metal foil wires. It should be noted that when the flame-suppressing layer 6 is constructed from a tape member, the pressing and winding tape 5 can be omitted. By placing the flame-suppressing layer 6 within the inner layer of the shielding layer 8, the flame-suppressing layer 6 also functions as a wear-suppressing layer to suppress friction between the shielding layer 8 and the core 4, suppressing the combustion of the covering layer 7 and improving resistance to bending and other actions.

[0059] Figure 3 The cable 1c shown is in Figure 2 (a) is a cable in which a conductive strip 81, serving as a conductive strip member, is wound around the cable 1a to form a shielding layer 8. When using the conductive strip 81 as the shielding layer 8, a reinforcing pressing and winding strip 5 can be provided on the outer layer side of the shielding layer 8, in addition to the inner layer side. Furthermore, a grounding shielding wire 82 for the conductive strip 81 can be provided in contact with the inner circumferential surface of the conductive strip 81. The shielding wire 82 is composed of stranded wire made by twisting multiple strands of metal wire such as soft copper wire together. The stranded wire is preferably a bundled stranded wire. By providing a bundled stranded wire, such as… Figure 3As shown, the shielding wire 82 easily falls into the core 4 side, so the shape of the shielding layer 8 formed by winding the conductive strip 81 easily becomes uniform along the circumference of the cable. Therefore, even if the shielding wire 82 is provided on the cable 1c, the shielding wire 82 is difficult to break when the cable 1c is repeatedly subjected to bending or other actions, and the conductive strip 81 can be suppressed from being damaged by the shielding wire 82.

[0060] The conductive strip 81 has a substrate and a conductive layer made of conductive resin disposed on the surface of the substrate. The substrate is made of a material based on a resin such as a polyolefin resin and is formed into a long strip. The conductive layer is made of a conductive resin based on a resin such as a polyolefin resin, in which conductive particles are dispersed. The conductive strip 81 is wound into a spiral shape with a portion of its width direction overlapping. By forming the shielding layer 8 from the conductive strip 81, the shielding layer 8 can be formed in the same process as the twisting of the core 4 and the winding of the pressing and winding strip 5. Therefore, compared with the case where the shielding layer 8 is formed from a woven shielding material, manufacturing time can be reduced and manufacturing costs can be reduced.

[0061] (Summary of implementation methods)

[0062] Next, the technical concept learned from the embodiments described above will be described by reference to the accompanying reference numerals and the like. However, the reference numerals and the like in the following description do not limit the constituent elements in the claims to the components specifically shown in the embodiments.

[0063] [1] A cable (1) having a core (4) consisting of a plurality of wires (2) and a sheath (7) covering the core (4) and forming an outermost layer, the sheath (7) being a smoke generation suppression layer that meets the cleanliness level 1 according to ISO 14644-1, and a combustion suppression layer (6) being provided between the sheath (7) and the core (4), the combustion suppression layer (6) having an oxygen index that is 5 or more greater than that of the sheath (7).

[0064] [2] According to the cable (1) of [1], the difference between the oxygen index of the covering layer (7) and the oxygen index of the combustion suppression layer (6) is 7 or more and 15 or less.

[0065] [3] According to the cable (1) described in [1], wherein the oxygen index of the combustion suppression layer (6) is 30 or higher and the oxygen index of the covering layer (7) is 25 or lower.

[0066] [4] According to the cable (1) of [1], wherein the mass of the sheath (7) per unit length of the cable is greater than the mass of the combustion suppression layer (6) per unit length of the cable.

[0067] [5] According to the cable (1) of [1], wherein the thickness of the combustion suppression layer (6) is more than 20% and less than 65% of the thickness of the covering layer (7).

[0068] [6] The cable (1a, 1c) according to [1] has a shielding layer (8) between the combustion suppression layer (6) and the core (4).

[0069] [7] According to the cable (1b) of [1], a shielding layer (8) is provided between the covering layer (7) and the combustion suppression layer (6).

[0070] [8] The cable (1a, 1b) according to [6] or [7], wherein the shielding layer (8) is composed of an interwoven shielding material made of multiple metal wires and multiple fiber wires.

[0071] [9] According to the cable (1a, 1b) of [6] or [7], wherein the shielding layer (8) is composed of a braided shielding material made of metal foil filaments with metal foil wound around the fiber filaments.

[0072]

[10] According to the cable (1c) of [6], the shielding layer (8) is formed by winding a conductive strip (81) as a conductive strip member.

[0073]

[11] According to the cable (1) described in [1], wherein the plurality of wires (2) are insulated wires (2a) consisting of a conductor (21) and an insulator (22) covering the conductor (21) and the surrounding area of ​​the insulator (22) having a specific gravity of 1.0 or less.

[0074] The embodiments of the present invention have been described above, but the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that the combinations of features described in the embodiments are not necessarily all necessary for the method to solve the problems of the invention. In addition, the present invention can be implemented with appropriate modifications without departing from its spirit.

Claims

1. A cable comprising a core containing a plurality of wires and a sheath covering the periphery of the core and forming an outermost layer. The coating layer includes a smoke generation suppression layer that meets Class 1 cleanliness standards according to ISO 14644-1. A combustion-inhibiting layer is provided between the coating layer and the core, and the combustion-inhibiting layer has an oxygen index that is 5 or more greater than that of the coating layer.

2. The electrical cable of claim 1, wherein, The difference between the oxygen index of the coating layer and the oxygen index of the combustion-inhibiting layer is greater than 7 and less than 15.

3. The cable of claim 1, wherein, The oxygen index of the combustion-inhibiting layer is above 30, and the oxygen index of the coating layer is below 25.

4. The cable according to claim 1, wherein, The mass of the sheath per unit length of the cable is greater than the mass of the flame-suppressing layer per unit length of the cable.

5. The cable according to claim 1, wherein, The thickness of the combustion suppression layer is more than 20% and less than 65% of the thickness of the coating layer.

6. The cable according to claim 1, wherein, A shielding layer is provided between the combustion suppression layer and the core.

7. The cable according to claim 1, wherein, A shielding layer is provided between the covering layer and the combustion suppression layer.

8. The cable according to claim 6 or 7, wherein, The shielding layer comprises an interwoven shielding material composed of multiple metal wires and multiple fiber wires.

9. The cable according to claim 6 or 7, wherein, The shielding layer comprises a woven shielding material made of metal foil filaments with metal foil wound around the fiber filaments.

10. The cable according to claim 6, wherein, The shielding layer is formed by winding a conductive strip, which is a conductive strip member.

11. The cable according to claim 1, wherein, The plurality of wires are insulated wires comprising a conductor and an insulator covering the conductor, the insulator having a specific gravity of 1.0 or less.

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