Cable and load detection method for cable

Abstract

To provide a cable and a load detection method for the cable that allow easy recognition of the degree of wear and the applied load.SOLUTION: This cable comprises a wire-like conductor, an insulator surrounding the conductor, a first sheath layer surrounding the insulator, a second sheath layer surrounding the first sheath layer, and a third sheath layer surrounding the second sheath layer, where the respective colors of the first, second, and third sheath layers differ from each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cable and a method for detecting a load on a cable. [Background technology]

[0002] In recent years, equipment with moving parts, such as industrial robots, has been widely used in production lines for manufacturing automobile parts, etc. During operation of the equipment, the moving parts are repeatedly bent, twisted, or stretched. Cables are used as power lines for supplying power to such moving parts and as signal lines for transmitting signals. Because cables used in moving parts are deformed by the bending, twisting, or stretching of the moving parts, they are more susceptible to wear and breakage than fixed cables.

[0003] Known examples of inventions relating to cables used in movable parts include the coaxial cable described in Patent Document 1. The coaxial cable described in Patent Document 1 includes a conductor, an insulating layer covering the conductor, a shielding layer covering the insulating layer, and a sheath covering the shielding layer. The invention described in Patent Document 1 aims to provide a coaxial cable that is less likely to break when bent or twisted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-44082 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, preventive or predictive maintenance efforts have been widely promoted to inspect equipment before malfunctions occur and prevent malfunctions from occurring. There is a demand for an easy way to grasp the degree of cable wear and the load on the cable before the conductor inside the cable is exposed and causes a ground fault, or before the conductor inside the cable is broken.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a cable and a method for detecting the load on the cable that allow the degree of wear and the load to be easily determined. [Means for solving the problem]

[0007] A cable according to one embodiment of the present invention includes a linear conductor, a first sheath layer surrounding the conductor, a second sheath layer surrounding the first sheath layer, and a third sheath layer surrounding the second sheath layer, wherein the first sheath layer, the second sheath layer, and the third sheath layer are all different in color.

[0008] In the above cable, the first sheath layer, the second sheath layer, and the third sheath layer are all different in color, so that an inspector can easily determine whether the cable is in a normal state, a caution state, or a warning state based on the degree of wear of the cable. As a result, the degree of wear of the cable can be easily and precisely determined.

[0009] A cable according to one embodiment of the present invention includes a linear conductor, a first sheath layer surrounding the conductor, and a second sheath layer surrounding the first sheath layer. The first sheath layer contains fluorescent paint that emits light when irradiated with electromagnetic waves of a specific wavelength.

[0010] According to the cable, by irradiating the side surface of the cable with electromagnetic waves of a specific wavelength, the degree of wear of the cable can be easily determined even in a dark place.

[0011] The cable may comprise a linear conductor, a first sheath layer surrounding the conductor, a second sheath layer surrounding the first sheath layer, and a third sheath layer surrounding the second sheath layer, wherein the first sheath layer, the second sheath layer, and the third sheath layer are different colors from one another, or a plurality of cables may comprise a linear conductor, a first sheath layer surrounding the conductor, and a second sheath layer surrounding the first sheath layer, wherein the first sheath layer contains fluorescent paint that emits light when irradiated with electromagnetic waves of a specific wavelength, and the sides of adjacent cables are joined by fusion.

[0012] According to the above configuration, even if the movable part is deformed by repeatedly bending, twisting, or expanding and contracting, it is possible to prevent the third sheath layers from rubbing against each other or the second sheath layers from rubbing against each other, and to prevent the cables from becoming tangled. Therefore, according to the above configuration, not only can the degree of wear be easily grasped, but wear can also be suppressed. As a result, the above configuration can contribute to high reliability and long life of the equipment.

[0013] A cable according to one embodiment of the present invention includes a linear conductor, an insulator surrounding the conductor, a shielding layer surrounding the insulator, an identification layer surrounding the shielding layer, and a transparent sheath layer surrounding the identification layer. The shielding layer includes a braid of tin-plated annealed copper wires or aluminum foil.

[0014] In the above cable, repeated bending, twisting, or expansion / contraction of the movable part causes repeated deformation of the cable, which in turn causes repeated deformation of the shielding layer. Repeated deformation of the shielding layer causes the tin-plated annealed copper wires, which are the elemental wires of the braid, to rub against each other, causing the tin contained in the tin plating to be scraped off and turned into powder, or the aluminum foil to be crushed and the aluminum contained in the aluminum foil to be turned into powder. The powdered tin or aluminum adheres to the identification layer. The powdered tin or aluminum has a larger surface area per unit volume than the tin or aluminum before it became powdered, making it more susceptible to oxidation when exposed to air. Tin and aluminum turn black when oxidized. Therefore, the powdered tin or aluminum adhering to the identification layer turns black due to oxidation, causing the identification layer to blacken. Furthermore, repeated bending, twisting, or expansion / contraction of the movable part causes the tin or aluminum to be powdered, and the powdered tin or aluminum to adhere to the identification layer. Therefore, the more the cable wears, the more the identification layer blackens. An inspector can visually check the side surface of the cable to see that the identification layer has turned black, and therefore, with this cable, the load on the cable can be easily determined.

[0015] A cable load detection method according to one embodiment of the present invention is a method for detecting a load on a cable used in a movable part. The cable includes a linear conductor, an insulator surrounding the conductor, a shield layer surrounding the insulator, an identification layer surrounding the shield layer, and a transparent sheath layer surrounding the identification layer. The shield layer includes a braid of tin-plated annealed copper wires or aluminum foil. The cable load detection method according to one embodiment of the present invention includes a powdering process in which the shield layer is repeatedly deformed, causing the tin contained in the tin plating or the aluminum contained in the aluminum foil to turn into powder, and a discoloration process in which the powdered tin or aluminum oxidizes, changing the color of the identification layer.

[0016] According to the cable load detection method, the identification layer darkens as the cable wear progresses. An inspector can confirm that the identification layer has darkened by visually inspecting the side of the cable. More specifically, the inspector can determine which part of the identification layer has darkened and which part of the cable is under greater load. This allows the inspector to repeatedly bend, twist, or stretch the movable part during a trial run before full-scale operation of the equipment, thereby determining which part of the cable is under greater load. Therefore, before full-scale operation of the equipment, it is possible to determine which part of the cable is under greater load. If a large load is found in an unexpected part, the cable routing can be reconsidered. As a result, the cable load detection method can extend the life of the cable used during full-scale operation of the equipment, contributing to higher reliability and longer life of the equipment.

[0017] In the cable and the cable load detection method, the color of the identification layer is preferably white. This increases the difference in brightness between the color of the identification layer in a normal state (white) and the color of the identification layer in a worn state (black), making it easier for an inspector to notice that the cable is in a worn state. It also makes it easier for an inspector to determine which parts of the identification layer have turned black. [Effects of the Invention]

[0018] According to the present invention, the degree of wear and load on the cable can be easily determined. [Brief explanation of the drawings]

[0019] [Figure 1] 1A is a perspective view of the cable 1. FIG. 1B is a cross-sectional view of the cable 1. [Figure 2] FIG. 2 is a perspective view of the cable 1a. [Figure 3] FIG. 3 is a cross-sectional view of the cable 1b. [Figure 4]FIG. 4 shows an example of a cable 1b discolored due to repeated deformation. DETAILED DESCRIPTION OF THE INVENTION

[0020] [First embodiment] A cable 1 according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 1(A) is a perspective view of the cable 1. Fig. 1(B) is a cross-sectional view of the cable 1.

[0021] As shown in FIG. 1(A), cable 1 includes a conductor 2, an insulator 3, a first sheath layer 4, a second sheath layer 5, and a third sheath layer 6. Cable 1 is flexible and is used, for example, in a production line for manufacturing automobile parts, etc., as a power line for supplying power to a moving part that repeatedly bends, twists, or expands and contracts, such as an industrial robot within the production line, or as a signal line for transmitting signals. Cable 1 has a cylindrical shape extending along a first direction DIR1, which is a predetermined direction. Note that cable 1 is not limited to a single-core cable, and may be a multi-core cable.

[0022] The conductor 2 is a stranded conductor formed by twisting together a plurality of strands 2a. The conductor 2 and the strands 2a are each electrically conductive. The conductor 2 and the strands 2a are made of a metal such as copper. The conductor 2 is linear and extends along a first direction DIR1. The conductor 2 may also be a solid wire.

[0023] The insulator 3 surrounds the conductor 2. The material of the insulator 3 is, for example, a resin such as polyvinyl chloride, polyethylene, or polyurethane.

[0024] The first sheath layer 4 surrounds the insulator 3. The first sheath layer 4 has insulating properties. The material of the first sheath layer 4 is, for example, a resin such as polyvinyl chloride, polyethylene, or polyurethane, or a rubber such as natural rubber. The first sheath layer 4 has a cylindrical shape extending along the first direction DIR1. The first sheath layer 4 protects the conductor 2 from external forces. In this embodiment, the first sheath layer 4 is colored yellow using a dye, pigment, or the like. The color of the first sheath layer 4 is not limited to yellow, and may be different from the colors of the second sheath layer 5 and the third sheath layer 6.

[0025] The second sheath layer 5 surrounds the first sheath layer 4. The second sheath layer 5 has insulating properties. The material of the second sheath layer 5 is, for example, a resin such as polyvinyl chloride, polyethylene, or polyurethane, or a rubber such as natural rubber. The second sheath layer 5 has a cylindrical shape extending along the first direction DIR1. The second sheath layer 5 protects the conductor 2 and the first sheath layer 4 from external forces. In this embodiment, the second sheath layer 5 is colored blue with a dye, pigment, or the like. The color of the second sheath layer 5 is not limited to blue, and may be different from the colors of the first sheath layer 4 and the third sheath layer 6.

[0026] The third sheath layer 6 surrounds the second sheath layer 5. The third sheath layer 6 has insulating properties. The material of the third sheath layer 6 is, for example, a resin such as polyvinyl chloride, polyethylene, or polyurethane, or a rubber such as natural rubber. The material of the third sheath layer 6 may be the same as or different from the materials of the first sheath layer 4 and the second sheath layer 5. The third sheath layer 6 has a cylindrical shape extending along the first direction DIR1. The third sheath layer 6 is a layer that forms the outermost layer of the cable 1, serving as an outer jacket. The third sheath layer 6 protects the conductor 2, the first sheath layer 4, and the second sheath layer 5 from external forces. In this embodiment, the third sheath layer 6 is colored black using a dye, pigment, or the like. The color of the third sheath layer 6 is not limited to black, and may be different from the colors of the first sheath layer 4 and the second sheath layer 5.

[0027] By visually inspecting the side of the cable 1, an inspector can determine whether the cable 1 is in a normal state, a caution state, or a warning state. The normal state, caution state, and warning state are classified according to the ease with which the conductor 2 is exposed. More specifically, if the entire side of the cable 1 is black, the cable 1 is in a normal state. In the normal state, the entire side of the conductor 2 is protected by the first sheath layer 4, the second sheath layer 5, and the third sheath layer 6, and the conductor 2 is unlikely to be exposed, i.e., the conductor 2 is unlikely to be subject to a ground fault.

[0028] If a portion of the side of the cable 1 is blue, a portion of the third sheath layer 6 has been worn away, and the cable 1 is in a state requiring attention. In the state requiring attention, a portion of the conductor 2 is protected only by the first sheath layer 4 and the second sheath layer 5, and is not protected by the third sheath layer 6. In the state requiring attention, the cable 1 is more worn out than in the normal state, making the conductor 2 more likely to be exposed, i.e., the conductor 2 is more likely to be subjected to a ground fault.

[0029] If a portion of the side of the cable 1 is yellow, a portion of the second sheath layer 5 and a portion of the third sheath layer 6 have been worn away, and the cable 1 is in a warning state. In the warning state, a portion of the conductor 2 is protected only by the first sheath layer 4, and is not protected by the second sheath layer 5 or the third sheath layer 6. In the warning state, the cable 1 is more worn out than in the caution state, making the conductor 2 more likely to be exposed, i.e., the conductor 2 is more likely to be prone to ground faults.

[0030] In the cable 1, the first sheath layer 4, the second sheath layer 5, and the third sheath layer 6 are all different in color, so that an inspector can easily determine whether the cable 1 is in a normal state, a caution state, or a warning state. Therefore, the cable 1 allows the inspector to easily and precisely determine the degree of wear of the cable 1.

[0031] It is preferable that the colors of the first sheath layer 4 and the second sheath layer 5 each have a relatively long wavelength. Colors with relatively long wavelengths include red (wavelength 640 to 770 nm), orange (wavelength 590 to 640 nm), yellow (wavelength 550 to 590 nm), green (wavelength 490 to 550 nm), and blue (wavelength 430 to 490 nm). This makes it easier to grasp the degree of wear of the cable 1 even from a distance.

[0032] The color of the first sheath layer 4 is preferably yellow or red. In particular, red is a color that strongly stimulates the human optic nerve, so if the color of the first sheath layer 4 is red, it can make the inspector strongly aware that the cable 1 is in a warning state.

[0033] In the above-described embodiment, dyes or pigments are used to color the first sheath layer 4, the second sheath layer 5, and the third sheath layer 6, respectively, to make them different colors. Alternatively, fluorescent paints that emit different colors when irradiated with light (electromagnetic waves) of a specific wavelength, such as black light, may be used to color the first sheath layer 4, the second sheath layer 5, and the third sheath layer 6. For example, the first sheath layer 4 may contain fluorescent paint that emits yellow light, the second sheath layer 5 may contain fluorescent paint that emits blue light, and the third sheath layer 6 may not contain fluorescent paint. In this case, by irradiating the side of the cable 1 with light (electromagnetic waves) of a specific wavelength, such as black light, an inspector can easily determine whether the cable 1 is in a normal state, a caution state, or a warning state. Therefore, the degree of wear of the cable 1 can be easily determined even in a dark place. The first sheath layer 4, the second sheath layer 5 and the third sheath layer 6 may be colored by combining a dye or a pigment with a fluorescent paint.

[0034] In the above-described embodiment, the cable 1 is divided into three states by setting the number of sheath layers of different colors to three or the number of sheath layers emitting different light colors to two. However, the cable 1 may be divided into two states by setting the number of sheath layers of different colors to two or the number of sheath layers that emit light when irradiated with light (electromagnetic waves) of a specific wavelength, such as black light, to one. In this case, the cable 1 can be manufactured more easily. The number of sheath layers of different colors may be four or more, or the number of sheath layers emitting different light colors may be three or more. In this case, the cable 1 can be divided into four or more states, allowing the degree of wear of the cable 1 to be grasped in more detail.

[0035] [First Modification] A cable 1a according to a first modified example of the present invention will be described below with reference to the drawings. Fig. 2 is a perspective view of the cable 1a.

[0036] As shown in FIG. 2, the cable 1a includes a plurality of cables 1. The side surfaces of adjacent cables 1 are joined by fusion splicing. The plurality of cables 1 are parallel to one another. In this modification, the cable 1a is a flat cable. However, the cable 1a does not have to be a flat cable.

[0037] Cable 1a also achieves the same effects as cable 1. Furthermore, cable 1a can prevent the third sheath layers 6 from rubbing against each other and prevent multiple cables 1 from becoming entangled, even if the movable part is repeatedly bent, twisted, or stretched and contracted, causing deformation of cable 1a. Therefore, cable 1a not only makes it easy to grasp the degree of wear of cable 1a, but also reduces wear of cable 1a. As a result, cable 1a can achieve a longer life for cable 1a, contributing to higher reliability and a longer life of equipment.

[0038] [Second embodiment] A cable 1b according to a second embodiment of the present invention will be described below with reference to the drawings. Fig. 3 is a cross-sectional view of the cable 1b. Note that in Fig. 3, reference symbols are assigned to only representative conductors 2 and insulators 3 among the plurality of conductors 2 and insulators 3.

[0039] Like the cables 1 and 1a, the cable 1b is also flexible and is used, for example, in a movable part. The cable 1b has a cylindrical shape extending in a predetermined direction. As shown in FIG. 3, the cable 1b includes a plurality of conductors 2, a plurality of insulators 3, a holding tape 7, a shielding layer 8, an identification layer 9, and a sheath layer 10. In this embodiment, the cable 1b is a multi-core cable. The configurations of the conductors 2 and the insulators 3 are similar to those of the conductors 2 and the insulators 3 in the cable 1, respectively, and therefore description thereof will be omitted. Furthermore, the cable 1b is not limited to a multi-core cable, and may be a single-core cable.

[0040] The conductors 2 and the insulators 3 surrounding the conductors 2 form a single bundle. The cable 1b includes multiple bundles. The insulators 3 prevent short-circuiting between the conductors 2 and between the conductors 2 and the shielding layer 8. To distinguish between the multiple conductors 2, it is preferable that the multiple insulators 3 are each different in color. Furthermore, to improve noise resistance, it is preferable that the multiple bundles are twisted together.

[0041] A pressure winding tape 7 is wound around the outer periphery of the multiple bundles. By bundling the multiple bundles, the pressure winding tape 7 supports the multiple conductors 2 and the multiple insulators 3. If the cable 1b is a single-core cable, the cable 1b does not need to be equipped with the pressure winding tape 7.

[0042] The shielding layer 8 surrounds the periphery of the pressure winding tape 7. The shielding layer 8 is electrically conductive. The shielding layer 8 covers the periphery of the conductor 2, thereby improving the noise resistance of the conductor 2. In this embodiment, the shielding layer 8 is a braid made of tin-plated annealed copper wires. If the cable 1b is a single-core cable, the shielding layer 8 only needs to surround the periphery of the insulator 3.

[0043] The identification layer 9 surrounds the periphery of the shield layer 8. The identification layer 9 is, for example, insulating paper. In this embodiment, the color of the identification layer 9 is white. Note that the identification layer 9 is not limited to insulating paper and may be conductive.

[0044] The sheath layer 10 surrounds the identification layer 9. The sheath layer 10 has insulating properties. The material of the sheath layer 10 is, for example, a resin such as polyvinyl chloride, polyethylene, or polyurethane, or a rubber such as natural rubber. The sheath layer 10 is a layer that serves as the outermost layer of the cable 1b. The sheath layer 10 is transparent.

[0045] Figure 4 shows an example of cable 1b that has been discolored due to repeated deformation. When visually inspecting the side of cable 1b before the equipment is put into operation, an inspector confirms that the entire side of cable 1b is white, the color of identification layer 9.

[0046] When the equipment is in operation and the movable part is repeatedly bent, twisted, or stretched, the cable 1b is repeatedly deformed, and accordingly, the shielding layer 8 is also repeatedly deformed. As the shielding layer 8 repeatedly deforms, the tin-plated annealed copper wires that make up the braid rub against each other, causing the tin contained in the tin plating to be scraped off and turn into powder (powdering process). The powdered tin adheres to the identification layer 9. Compared to the tin before powdering, the powdered tin has a larger surface area per unit volume and is more susceptible to oxidation when exposed to air. When tin oxidizes, it turns black. Therefore, the powdered tin adhering to the identification layer 9 turns black through oxidation, and the color of the identification layer 9 changes from white to black, as shown in Figure 4 (discoloring process). Further repeated bending, twisting, or stretching of the movable part further powders the tin, and the powdered tin adheres to the identification layer 9. Therefore, the more the cable 1b wears, the more the identification layer 9 turns black. By visually inspecting the side of cable 1b, an inspector can confirm that the color of identification layer 9 has changed from white to black. Therefore, cable 1b makes it easy to grasp the load on cable 1b. As a result, cable 1b can be repaired or replaced before conductor 2 inside cable 1b is exposed and a ground fault occurs, or before conductor 2 inside cable 1b is broken.

[0047] Furthermore, the inspector can determine which part of the identification layer 9 has changed color from white to black, and can determine which part of the cable 1b has been subjected to a greater load. For example, if the movable part is repeatedly bent, twisted, or stretched during a trial run before the equipment is put into full operation, it is possible to determine which part of the cable 1b has been subjected to a greater load. Therefore, before the equipment is put into full operation, it is possible to confirm which part of the cable 1b has been subjected to a greater load. If a greater load is found in an unexpected part, the cable routing can be reconsidered. As a result, the life of the cable used during full-scale operation of the equipment can be extended, contributing to the high reliability and long life of the equipment.

[0048] When the above-mentioned load detection method is used during the trial operation phase, the cable 1b used for load detection can be made the same as the cable used when the equipment is in full operation, thereby making it possible to make the behavior of the cable the same and more accurately simulate the load on the cable when the equipment is in full operation.

[0049] The color of the identification layer 9 is not limited to white. However, by making the color of the identification layer 9 white, the difference in brightness between the color (white) of the identification layer 9 in the normal state and the color (black) of the identification layer 9 in the state where the cable 1b is worn becomes larger, making it easier for an inspector to notice that the cable 1b is in a worn state.

[0050] The shielding layer 8 may also be a conductive tape made by laminating aluminum foil to a polyethylene terephthalate film. Repeated deformation of the shielding layer 8 causes the aluminum foil to be crushed, and the aluminum contained in the aluminum foil becomes powdered (powdering process). The powdered aluminum adheres to the identification layer 9. The powdered aluminum has a larger surface area per unit volume than the aluminum before it became powdered, and is more susceptible to oxidation when exposed to air. When aluminum oxidizes, it turns black. Therefore, the powdered aluminum adhering to the identification layer 9 turns black through oxidation, causing the color of the identification layer 9 to change from white to black (discoloration process). Furthermore, repeated bending, twisting, or expansion / contraction of the movable part further powders the aluminum, and the powdered aluminum adheres to the identification layer 9. Therefore, the more the cable 1b wears, the more the identification layer 9 blackens.

[0051] The above-described embodiments and modifications are illustrative in all respects and are not restrictive. The scope of the present invention is defined not by the above-described embodiments and modifications but by the claims. Furthermore, the scope of the present invention is intended to include all modifications that are equivalent to and within the scope of the claims. [Explanation of symbols]

[0052] 1, 1a, 1b: cable, 2: conductor, 2a: wire, 3: insulator, 4: first sheath layer, 5: second sheath layer, 6: third sheath layer, 7: pressure winding tape, 8: shield layer, 9: identification layer, 10: sheath layer, DIR1: first direction

Claims

1. a linear conductor; an insulator surrounding the conductor; a first sheath layer surrounding the insulator; a second sheath layer surrounding the first sheath layer; a third sheath layer surrounding the second sheath layer; It is equipped with the first sheath layer, the second sheath layer, and the third sheath layer have different colors; cable.

2. a linear conductor; an insulator surrounding the conductor; a first sheath layer surrounding the insulator; a second sheath layer surrounding the first sheath layer; It is equipped with The first sheath layer contains a fluorescent paint that emits light when irradiated with electromagnetic waves of a specific wavelength. cable.

3. A plurality of cables according to claim 1 or claim 2 are provided, Adjacent sides of the cable are joined by fusion splicing. cable.

4. a linear conductor; an insulator surrounding the conductor; a shield layer surrounding the insulator; an identification layer surrounding the shield layer; a transparent sheath layer surrounding the identification layer; It is equipped with The shield layer includes a braid of tin-plated annealed copper wires or aluminum foil. cable.

5. A method for detecting a load on a cable used in a moving part, comprising: The cable a linear conductor; an insulator surrounding the conductor; a shield layer surrounding the insulator; an identification layer surrounding the shield layer; a transparent sheath layer surrounding the identification layer; It is equipped with the shield layer includes a braid of tin-plated annealed copper wires or aluminum foil, a powdering step in which the shielding layer is repeatedly deformed, and the tin contained in the tin plating or the aluminum contained in the aluminum foil is powdered; a discoloration process in which the powdered tin or aluminum is oxidized and the color of the identification layer changes; Equipped with Cable load detection method.

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