JP5354966B2 - Telescopic wire - Google Patents

Description

  The present invention relates to a stretchable electric wire having stretchability, and more particularly to a stretchable wire excellent in stretch recovery and friction durability, which is suitable for robots and wearable electronic devices.

In recent years, the development of robots has been remarkable, and robots with various movements are appearing. In addition, various types of wearable electronic devices that can be worn on the human body and clothes have been developed. Many electric wires for power and signal transmission are used in these robots and wearable electronic devices. However, in general, an electric wire has a structure in which a copper wire is a core and an outer periphery thereof is covered with an insulator, and has almost no elasticity. For this reason, it is necessary to wire the electric wires with a large margin so as not to hinder the movement of the robot or the human body, and this often becomes an obstacle in device design and practical use.
Especially in the state-of-the-art humanoid robots and power assist devices that are attached to the human body to assist muscle strength, electric wires for moving the motor at the end via a multi-degree-of-freedom joint, and various sensors equipped at the end There are a number of electric wires for transmitting signals from the cable, and there is a need to give the wires elasticity in order to increase the degree of freedom of the wiring in the multi-degree-of-freedom joint.

A typical example of a stretchable electric wire is a curled cord that can be expanded and contracted by making the electric wire into a coil shape, and is used in fixed telephones, etc., but is generally thick and heavy. This is not suitable for humanoid robots and power assist devices that use many wires.
On the other hand, as a technique related to an expandable electric wire having elasticity in the electric wire itself, for example, in Patent Document 1, an outer periphery of a core yarn formed by winding an inelastic yarn in a state where the elastic yarn is stretched about twice, An expandable electric wire in which a copper foil is spirally wound is disclosed, and a yarn made of a polyurethane synthetic fiber, natural rubber, and a heat-resistant silicone resin is described as an elastic yarn.

Further, in Patent Document 2, an elastic fiber filament yarn is used as a core, and a fiber bundle is wound or arranged around an elastic fiber filament yarn stretched 1.5 to 3.5 times. A metal wire composite elastic yarn in which a metal wire is spirally wound is disclosed, and there is a description that the diameter of the elastic fiber filament yarn needs to be three times or more the diameter of the metal wire. Various elastomer fibers such as polyurethane elastomer, natural rubber, and synthetic rubber are described.
Furthermore, Patent Document 3 discloses an expandable electric wire in which a plurality of core wires each having a conductive wire disposed on the outer periphery of a core material made of elastic elastic yarn is covered with false twisted yarn, and the elastic yarn has elastic recovery properties. Good and strong are preferred, and there is a description that synthetic rubbers such as natural rubber, polyurethane and silicone rubber are suitable as examples.

As described above, a conventional stretchable electric wire is generally manufactured by winding an inelastic yarn around its outer periphery in a state where the elastic yarn is stretched, and further winding a metal wire around its outer periphery. Any material may be used as long as it is an elastic yarn, and among them, a thick elastic yarn or a strong elastic yarn, that is, a relatively hard elastic yarn has been suitable.
An electric wire manufactured by such a method provides a stretchable electric wire having a higher extensibility as the ratio of the elastic yarn stretched when winding the metal wire returns to the original length increases. However, since the wound metal wire is tightening the elastic yarn, it cannot sufficiently return to the original length only with the stretch recovery force of the stretched elastic yarn, so the stretchability of the electric wire is insufficient. There was a problem.

In addition, an electric wire in which a metal wire is wound on a hard core material has a structure in which the metal wire protrudes from the surface of the core material, so that the metal wire is easily damaged or cut due to friction with surrounding structures. In order to prevent damage, if the surface of the metal wire is covered firmly, there is a problem that the stretchability is greatly inhibited.
Furthermore, wires that use thick elastic fibers or hard elastic fibers as the core material require a large force to stretch the wires, and humanoid robots and power assist devices that use many wires have a large energy loss. In addition, there is a problem that the weight of the motor increases due to the need for a motor with higher power, and the wearable electronic device has a problem that the movement of the body is obstructed.

JP 61-290603 A Japanese Patent Publication No. 64-3967 JP 2004-134313 A

  An object of the present invention is to provide an expandable electric wire that is excellent in repeated stretch recovery and friction durability and can be expanded and contracted with a small force.

In order to solve the above problems, the present inventors have focused on the core material used for the stretchable electric wire, found that the above problem can be solved by using a core material having specific compression characteristics, and have made the present invention. .
That is, the present invention is as follows.
(1) In a stretchable electric wire formed by winding a conductor wire around a stretchable elastic core material, the core material has a 50% elongation recovery rate of 80% or more, and a lateral stress at the time of 50% elongation recovery. An expandable electric wire characterized by being 0.05 cN / mm ² or more and having a 50% compressive stress in the lateral direction of 5 to 100 cN / mm ² .
(2) The expandable electric wire according to (1) above, wherein the core material has a 50% elongation stress of 1 to 200 cN / mm ² .
(3) The expandable electric wire according to (1) or (2) above, wherein the core material is a porous elastic body.
(4) The expandable electric wire according to any one of (1) to (3), wherein the core member is an elastic body having at least one hollow portion continuous in the longitudinal direction.
(5) The expandable electric wire according to any one of (1) to (4) above, wherein the core material is a knitted or braided string made of elastic long fibers.
(6) The expandable electric wire according to any one of (1) to (5) above, wherein the expandable electric wire has a covering portion on an outer periphery thereof.

  The stretchable electric wire of the present invention is excellent in repeated stretch recovery, and has excellent friction durability because the conductor wire has a structure wound in a state of being appropriately buried in the core material. In addition, since it can be expanded and contracted with a small force, it is suitable for humanoid robots, power assist devices, wearable electronic devices and the like using a large number of extendable electric wires.

The present invention will be specifically described below.
The stretchable electric wire of the present invention has a structure in which a conductor wire is wound around a core material made of a stretchable elastic body. The core material used for the stretchable electric wire of the present invention needs to be an elastic body having a 50% elongation recovery rate of 80% or more, preferably 85% or more, and more preferably 90%. 50%
When the elongation recovery rate is within this range, an expandable electric wire excellent in repeated elongation recovery can be obtained. Further, the breaking elongation of the core material is preferably 100% or more, more preferably 150% or more, and particularly preferably 200% or more. When the breaking elongation is within this range, an expandable electric wire having high extensibility can be obtained.

  As a typical manufacturing method of the expandable electric wire of the present invention, a method of winding a conductor wire in a spiral shape with a core material extended between two pairs of rollers, as will be described later, can be mentioned. At this time, the core material, which is an elastic body, is elongated in the longitudinal direction, and at the same time, contracts, that is, becomes thin, in a direction perpendicular thereto. Accordingly, the conductor wire is wound around the core material that is thinner than the normal state. After that, the core material wound with the conductor wire is sufficiently relaxed when it comes out of the exit side roller, and tries to return to the original length. At this time, the core material tries to return to the original length. Simultaneously with the force (force in the longitudinal direction of the core material), a force (force in the direction perpendicular to the longitudinal direction of the core material) is generated to return to the original thickness. The greater the force with which the core material tries to return to the original thickness, the more the conductor wire wound around the core material is pushed out in the outer circumferential direction, so the rate at which the core material returns to the original length increases. Thus, an extensible electric wire with high extensibility is obtained.

The characteristic value representing the force with which the core material returns to its original thickness is the lateral stress at the time of 50% elongation recovery, and the core material used for the expandable electric wire of the present invention has the lateral stress at the time of 50% elongation recovery. Is 0.05 cN / mm ² or more, preferably 0.1 cN / mm ² or more. When the lateral stress at the time of 50% elongation recovery is within this range, the force that pushes the wound conductor wire in the outer peripheral direction is sufficiently exerted, and the core material stretched when the conductor wire is wound is the original length. The ratio of returning to is sufficiently large, and an extensible electric wire with high extensibility is obtained. Furthermore, even when the telescopic wire is repeatedly expanded and contracted, the stretched wire is easy to return to its original length, so that the problem that the wire does not stretch and does not return to its original length is less likely to occur, and repeated stretch recovery is possible. Can be obtained.
However, the core material that has too much lateral stress at the time of 50% elongation recovery also increases the compressive stress in the lateral direction of the core material, and has a structure in which a conductor wire protrudes from the surface of the core material. since easily occur such as friction damage or disconnection of the conductor wires by lateral stress at 50% elongation recovery is preferably 5 cN / mm ² or less, 2 cN / mm ² or less being more preferred.

Core material used for the elastic wire of the present invention, 50% compression stress in the transverse direction is required to be 5~100cN / mm ^2, more preferably ^{10~90cN / mm 2, 20~80cN / mm} 2 is Further preferred is 25 to 75 cN / mm ² . When the lateral 50% compressive stress is within this range, the conductor wire is partially embedded in the surface of the core material as shown in FIG. 1, so the conductor wire is caused by friction or contact with the surrounding structure. It is difficult to cause damage and cutting, and an elastic wire with excellent friction durability can be obtained.
In addition, for the purpose of protecting the conductor wire, it is common that the periphery of the electric wire is covered with insulating fiber or insulating resin. There is a problem of being. If the stretchable wire of the present invention has a structure in which the conductor wire is partially embedded in the surface of the core material, the outer covering for protecting the conductor wire can be thinned, so that the high stretchability can be maintained. can get.

The core material used for the expandable electric wire of the present invention preferably has a 50% elongation stress of 1 to 200 cN / mm ² , more preferably 5 to 100 cN / mm ² , and particularly preferably 10 to 50 cN / mm ² . When the 50% elongation stress is in this range, an expandable electric wire that can be extended with a small force can be obtained, and an expandable electric wire suitable for applications using a large number of expandable wires, such as humanoid robots, power assist devices, wearable electronic devices, etc. It becomes.
As a force required for extending the stretchable electric wire of the present invention, a 30% extension load is preferably 5000 cN or less, more preferably 3000 cN or less, further preferably 1000 cN or less, and particularly preferably 500 cN or less.

The core material satisfying the above characteristic values used for the expandable electric wire of the present invention can be obtained by appropriately selecting the type and structure of the elastic body used for the core material. For example, a porous elastic body, an elastic body having at least one hollow part continuous in the longitudinal direction, a knitted or braided string made of elastic long fibers, or a structure in which insulating fibers are wound around the elastic body However, the core material is not limited to these as long as the core material satisfies the above characteristic values.
As the porous elastic body, for example, a thermoplastic elastomer such as polyurethane-based elastomer, polyester-based elastomer, polyamide-based elastomer, or a rubber material such as silicone rubber, ethylene-propylene rubber, chloroprene rubber, or butyl rubber is made porous. preferable.
A conventionally known method may be used as a method for making the pores. For example, when a foaming agent that decomposes by heating to generate a gas such as carbon dioxide or nitrogen is contained in the thermoplastic elastomer or rubber material, it is made into a fiber. At the same time or after fiberization, there is a method of foaming to make it porous. Examples of the foaming agent include organic foaming agents such as azodicarbonamide, azobisisovityronitrile, trihydrazinotriazine, inorganic foaming agents such as calcium carbonate, ammonia bicarbonate, and peroxide, and mixtures thereof. Although a foaming agent can be used, it is preferable to use a suitable one in accordance with the melting point of the thermoplastic elastomer or rubber material.

In addition, as another method, soluble particulate material is contained in the thermoplastic elastomer or rubber material, and the particulate material is eluted by immersing it in a solvent that dissolves the particulate material after fiberization but does not dissolve the fibrous material, There is a method of making it porous. The particulate material is preferably a water-soluble material, and inorganic salts such as sodium chloride and sodium sulfate, and organic substances such as glucose and sucrose can be used as extremely fine particles. In addition to these low molecular weight compounds, water-soluble polymer materials can also be used, such as starch.
The degree of porosity is combined with the characteristics of the elastic body used so as to satisfy the 50% elongation recovery rate, the lateral stress at the time of 50% elongation recovery, and the 50% compressive stress in the lateral direction specified in the present invention. What is necessary is just to set suitably.

  As a kind of core material used for the expandable electric wire of the present invention, a core material made of an elastic body having at least one hollow portion continuous in the longitudinal direction is also preferably used. Specifically, hollow elastic yarns made of thermoplastic elastomers such as polyurethane elastomers, polyester elastomers and polyamide elastomers, and rubber materials such as silicone rubber, ethylene propylene rubber, chloroprene rubber and butyl rubber are preferred. The hollow ratio calculated from the cross-sectional area of the hollow elastic yarn is preferably 3 to 50%, more preferably 5 to 30%, and still more preferably 10 to 25%.

  The method for producing the hollow elastic yarn is not particularly limited. For example, when a thermoplastic elastomer is used, a method using a known spinneret used when melt spinning a synthetic fiber having a hollow cross section is preferable. In the case of hollow elastic yarn made of silicone rubber, for example, a silicone rubber compound containing silicone rubber, a vulcanizing agent, and other additives as necessary is extruded into a hollow fiber shape, and then vulcanized in a vulcanizing furnace. A method of performing stretching while heating is preferred. Examples of the silicone rubber include a millable type and a liquid type, but the type is not particularly limited.

Moreover, the core material used for the expandable electric wire of the present invention may be a porous hollow elastic yarn made of a porous elastic body and having at least one hollow portion continuous in the longitudinal direction. The porous hollow elastic yarn can be produced by appropriately combining the method for producing the porous elastic yarn and the method for producing the hollow elastic yarn.
Such porous elastic yarns, hollow elastic yarns and porous hollow elastic yarns may be monofilaments or multifilaments. Further, it may be a multilayer structure having a plurality of layers having different compression characteristics in the radial direction of the elastic yarn. For example, a two-layer elastic yarn having a non-porous elastic body as an inner layer and a porous layer as an outer layer. It may be. In addition, an elastic body that is difficult to manufacture such as melt spinning may be a so-called slit yarn in which an elastic body is formed into a sheet and then cut and divided at an arbitrary width.

  Furthermore, it is also preferable to use a knitted or braided string made of elastic long fibers for the core material as the type of the core material used for the expandable electric wire of the present invention. A knitted or braided string made of elastic long fibers has a string-like shape in which the elastic long fibers contain an appropriate space inside, so that it is stretched and compressed as if it were a porous elastic yarn or a hollow elastic yarn. A core material having the following is obtained. The elastic long fibers used for the braided cord or braided cord are preferably thermoplastic elastomers such as polyurethane elastomers, polyester elastomers, and polyamide elastomers. The elastic long fiber may be a monofilament or a multifilament. The preferred fineness of the elastic long fiber is preferably 10 to 5000 dtex, more preferably 30 to 2000 dtex.

  A knitted string made of elastic long fibers can be manufactured, for example, by feeding and knitting elastic long fibers (usually one) to a small-diameter cylindrical knitting machine (string knitting machine). It can be manufactured by feeding elastic long fibers to a string making machine and braiding them. At this time, since the elastic long fiber has a high frictional force on the surface, it may be difficult to produce it even if it is fed to a small-diameter cylindrical knitting machine or a string making machine as it is. It is preferable to cover by covering with synthetic fibers such as crimped yarn (preferably crimped yarn such as false twisted yarn). At this time, the fineness of the synthetic fiber to be coated is preferably smaller than the fineness of the elastic long fiber, and more preferably 1/5 or less of the elastic long fiber.

In the stretchable electric wire of the present invention, after the insulating fiber is wound around the elastic body, the conductor wire may be wound around the outer periphery thereof. By winding the insulating fiber around the core material, it is possible to reduce the friction with the conductor wire and facilitate winding of the conductor wire. Also, by winding the insulating fiber with a thickness of a certain degree or more, it is possible to wind the conductor wire with a larger winding diameter than when the conductor wire is wound directly on the core material. The wire can be wound, and the elongation stress per cross-sectional area of the telescopic wire can be reduced. The thickness of the insulating fiber to be wound is preferably 0.1 mm to 3 mm, more preferably 0.1 mm to 2 mm, and still more preferably 0.1 mm to 1 mm. Moreover, it is preferable to apply a smoothing agent such as a silicone resin to the surface of the insulating fiber because friction with the conductor wire can be further reduced.
As a cross-sectional shape of the core material used for the expandable electric wire of the present invention, a shape without an acute angle portion or a protruding portion is preferable so that the conductor wire can be wound with a constant radius of curvature as much as possible. Specifically, a round cross section is most preferable, and a flat cross section or a polygon may be used. Moreover, the polygon in which the acute angle part was formed in the curved surface form may be sufficient.
The outer diameter of the core material used for the stretchable wire of the present invention may be appropriately set according to the thickness of the intended stretchable wire, but is preferably in the range of 0.01 to 10 mm, and 0.02 to 5 mm. More preferably, 0.1 to 3 mm is more preferable, and 0.2 to 2 mm is particularly preferable.

The stretchable electric wire of the present invention has a structure in which a conductor wire is wound around the core material. The conductor wire may be a single wire or an aggregated line of fine wires, but is preferably an aggregated line of at least two fine wires. By using the aggregated wires of the thin wires, the flexibility of the conductor wires is increased and it becomes difficult to inhibit the stretchability, so that a thinner stretchable electric wire can be easily obtained.
Various methods are known for assembling thin lines, and any method known in the present invention may be used. However, since it is difficult to wind the wire simply by aligning it straight, it is preferable to use a stranded wire. Moreover, in order to exhibit flexibility, what gathered the assembly line with the insulating fiber can also be used.
The diameter of the thin wire constituting the conductor wire is preferably 1 mm or less, more preferably 0.1 mm or less, particularly preferably 0.08 mm or less, and most preferably 0.05 mm or less. If the diameter of the thin wire is within this range, the flexibility of the conductor wire is increased, the stretchability is hardly hindered, the disconnection due to the stretch is less likely to occur, and a thinner stretchable electric wire is easily obtained. Since it will be easy to disconnect at the time of a process when too thin, 0.01 mm or more is preferable.

When the conductor wire is used as an aggregate wire of thin wires, the converted diameter of the conductor wire obtained by the following formula is preferably 2 mm or less, more preferably 1 mm or less, and further preferably 0.5 mm or less.
Equivalent diameter of conductor wire = 2 × √ ((π × (Lt / 2) × (Lt / 2) × n / π) = Lt × √n
Lt: Diameter of the fine wire constituting the conductor wire n: Number of aggregates of the fine wire constituting the conductor wire If the converted diameter of the conductor wire is within this range, the flexibility is good and the wire can be wound stably. Moreover, from the point of workability | operativity at the time of winding, 0.01 mm or more is preferable and, as for the conversion diameter of a conductor wire, 0.02 mm or more is more preferable.

The conductor wire preferably has a specific resistance of 10 ⁻⁴ Ω · cm or less, and more preferably 10 ⁻⁵ Ω · cm or less. The conductor wire is preferably a copper wire made of copper by 80 wt% or more, or an aluminum wire made of aluminum by 80% or more. Copper wire is most preferred because it is relatively inexpensive and has low electrical resistance. Aluminum wires are preferred after copper wires because they are lightweight. Copper wire is generally annealed copper wire or tin-copper alloy wire, but strong copper alloy with increased strength without significantly reducing electrical conductivity (for example, iron, phosphorus and indium added to oxygen-free copper) ), Tin, gold, silver, platinum or the like plated to prevent oxidation, or those treated with gold or other elements to improve the electrical signal transmission characteristics can also be used.

The conductor wires can be used one by one covered with an insulator, or a set of fine wires can be covered together with an insulator. The thickness of the insulator to be coated is preferably 2 mm or less, more preferably 1 mm or less, and still more preferably 0.1 mm or less. If the thickness of the insulator to be covered is within this range, the insulated conductor wire is flexible and has a small outer diameter.
As the type of the insulator to be coated, any one of the well-known insulating resins that meets the above-described purpose can be arbitrarily selected. When resin coating is applied to each conductor wire, for example, as a so-called enamel coating used for general magnet wires, polyurethane coating, polyurethane-nylon coating, polyester coating, polyester-nylon coating, polyester-imide coating, and polyesterimide- Polyamideimide coating etc. are mentioned. In the case where the resin coating is performed after forming the assembly line, a vinyl resin, a polyolefin resin, a fluororesin, a urethane resin, an ester resin, or the like can be used. For identification, each conductor wire can be color-coded in advance.

  A conductor wire coated with an insulating fiber in advance can also be used. As the insulating fibers, known insulating fibers such as fluorine fibers, polyester fibers, nylon fibers, polypropylene fibers, vinyl chloride fibers, saran fibers, glass fibers and polyurethane fibers can be used. The conductor wire can be covered by winding and / or braiding insulating fibers on the conductor wire. A conductor wire previously coated with an insulating fiber is preferable because the insulating resin layer on the surface of the thin wire is not easily broken during processing.

Next, the typical manufacturing method of the expansion-contraction electric wire of this invention is demonstrated. In addition, the expansion / contraction electric wire of this invention is not limited to the following manufacturing methods.
A typical method for producing the expandable electric wire of the present invention includes a method in which one or a plurality of conductor wires are spirally wound in a state where the core material is extended between two pairs of rollers. In order to easily develop stretchability, the core material is preferably elongated by 30% or more, more preferably 50% or more, and particularly preferably 100% or more.

Examples of the method of winding the conductor wire in a spiral shape include a method of winding the conductor wire using a covering machine. When winding a plurality of conductor wires, it is possible to wind in both the S twist direction and the Z twist direction using a double covering machine, or to wind only in one direction. If winding is performed in both the twisting directions, disconnection is likely to occur due to friction between the conductor wires, and thus winding in only one direction is preferable. The winding can be performed several times at a time, or several times at a time. When winding a plurality of wires in the same direction, adjacent conductor wires may intersect, so it is possible to wind a bobbin that has been drawn in advance by aligning a plurality of wires on one bobbin at a time. preferable.

  Moreover, it can also wind by the method of braiding a conductor wire on the outer periphery of a core material using a stringing machine etc. The conductor wire to be wound may be one or plural, and the direction of braiding of the conductor wire may be one direction or both directions. However, in the case of the braiding method, a plurality of conductor wires are not crossed at a time. A method of winding a plurality of conductor wires in one direction is preferable because they can be wound in parallel. For example, if the conductor wires are braided in one direction and the insulating fibers are braided in the opposite direction, the conductor wires can be prevented from being worn due to expansion and contraction. Insulating fibers can also be wound at the same time. For example, by arranging insulating fibers between a plurality of conductor wires braided in one direction and arranging insulating fibers in the opposite direction, the conductor wires can be expanded and contracted. This is particularly preferable because it can prevent overlapping and short circuit.

  Furthermore, in an expandable electric wire having a plurality of conductor wires, there are cases where two signal wires and two power wires are used. In this case, if the spacing between the signal lines is non-uniform, there is a problem that the characteristic impedance between the signal lines becomes non-uniform and the transmission loss increases (especially at high frequencies). A structure in which a plurality of conductor wires are in one direction and the insulating fibers are braided in the opposite direction, or the insulating fibers are arranged in the same direction between the plurality of conductor wires, and the braided in which the insulating fibers are arranged in the opposite direction. A transmission loss is particularly low, which is particularly preferable. At this time, in order to make the interval between the signal lines more uniform, the insulating fibers arranged in the direction opposite to the conductor lines are preferably thinner than the insulating fibers arranged in the same direction as the conductor lines. A fineness of 2 to 1/10 is more preferred.

The winding or braiding angle of the conductor wire (hereinafter represented by the winding angle) is preferably in the range of 30 degrees to 80 degrees. If the winding angle is within this range, the stretchability is easily developed. The winding angle is more preferably 35 ° to 75 °, and particularly preferably 40 ° to 70 °. In the present invention, the winding angle is an angle formed between the length direction (axial direction) of the expandable electric wire and the conductor wire when the expandable electric wire is viewed from the side, and refers to an angle when the expandable electric wire is in a relaxed state. The winding angle is obtained by using an inverse trigonometric function by cutting a loose stretchable electric wire for a certain length, unwinding the wound conductor wire and measuring its length.
In the expandable electric wire of the present invention, after winding a conductor wire around a core material, a covering portion is usually formed on the outer periphery thereof. The outer periphery covering portion is required to protect the inner conductor wire without hindering stretchability. For this reason, it is preferable to form with the braid | blade of an insulating fiber and / or the elastic tube-like thing of insulating resin with an elongation of 50% or more.

  When the outer periphery covering portion is formed by braiding insulating fibers, the intermediate body in which the conductor wire is wound around the core material is again placed on a stringing machine or the like, and the intermediate fibers are braided and the insulating fibers are braided on the outer periphery. The method is preferred, and the final shape of the braid may be round string or narrow tape. Further, a plurality of intermediate bodies in which conductor wires are wound around a core material may be collected and the outer periphery thereof may be covered with insulating fibers, or a plurality of intermediate bodies that have been previously coated with insulating fibers may be combined and further The outer periphery may be covered with insulating fibers. Preferably, a plurality of conductor wires wound around the core material at the same time and the outer periphery thereof is covered with insulating fibers can be made most compact.

As the insulating fiber covering the outer periphery, a multifilament or a spun yarn can be used, and it can be arbitrarily selected from known insulating fibers according to the use of the expandable electric wire and the assumed use conditions. The insulating fiber may be a raw yarn, but an original yarn or a pre-dyed yarn can also be used from the viewpoint of design properties and prevention of deterioration. In addition, the finish processing can improve flexibility and friction resistance. In addition, handling of known fibers such as flame retardant processing, water repellent processing, oil repellent processing, antifouling processing, antibacterial processing, antibacterial processing, and deodorizing processing can also improve handling in practical use. it can. In particular, it is preferable to apply a smoothing agent such as a silicone resin to the surface of the insulating fiber because the friction coefficient on the surface of the stretchable electric wire can be further reduced. In addition, when used for the skin wiring of a humanoid robot, it is preferable to apply a water repellent treatment to the outer peripheral covering portion so that the resin constituting the skin does not penetrate into the inside of the stretchable electric wire and impair the stretchability.

  Examples of insulating fibers that achieve both heat resistance and wear resistance include aramid fibers, polysulfone fibers, and fluorine fibers. From the viewpoint of fire resistance, glass fiber, flame-resistant acrylic fiber, fluorine fiber and saran fiber are mentioned, and from the viewpoint of wear resistance and strength, high-strength polyethylene fiber and polyketone fiber are mentioned. From the viewpoint of cost and heat resistance, there are polyester fiber, nylon fiber and acrylic fiber. Also suitable are flame retardant polyester fiber, flame retardant nylon fiber, flame retardant acrylic fiber (modacrylic fiber) and the like imparted with flame retardancy. For local deterioration due to frictional heat, it is preferable to use non-melted fibers. Examples thereof include aramid fibers, polysulfone fibers, cotton, rayon, cupra, wool, silk and acrylic fibers. When emphasizing strength, examples include high-strength polyethylene fiber, aramid fiber, and polyphenylene sulfide fiber. When importance is attached to frictional properties, examples thereof include fluorine fibers, nylon fibers, and polyester fibers. When emphasizing design properties, acrylic fibers with good color can be used. Furthermore, when importance is attached to the tactile sensation due to human contact, cellulosic fibers such as cupra, acetate, cotton, and rayon, and silk or synthetic fibers with fine fineness can be used.

When it is desired to improve the coating property from the liquid, an elastic resin elastic tube-like material can be suitably used as the outer coating. The insulating resin can be arbitrarily selected from various elastic insulating resins, and can be selected in consideration of compatibility with other insulating fibers used for the extension wire and the internal structure of the extension wire.
Performances that should be considered include elasticity, abrasion resistance, heat resistance, and chemical resistance. Synthetic rubber-based elastic materials are examples of those that are excellent in these performances, such as fluorine rubber, silicone rubber, and ethylene. Propylene rubber, chloroprene rubber and butyl rubber are preferred.

The outer coating layer made of an insulating material can be a combination of a coating braided with insulating fibers and an elastic tubular material. In many cases, the expansion / contraction electric wire is desired to be expanded / contracted with a small force. However, when the elastic wire is covered only with an elastic tube-like material, it is necessary to increase the thickness of the elastic tube, and the force necessary for expansion / contraction tends to increase. In such a case, it is possible to achieve both coverage and stretchability by combining a thin tube and a braid made of insulating fibers.
If necessary, an integrated layer made of an elastic material can be provided before providing the covering portion on the intermediate body obtained by winding the conductor wire around the core material. Since this integrated layer is mainly intended to prevent deviation between the conductor wire and the core material, it is not necessarily a continuous layer as long as the purpose can be achieved.
For the integrated layer, after winding the conductor wire on the core material, the obtained structure is immersed in the elastic liquid material, or at least the elastic liquid material is applied on the wound conductor wire Then, after removing the liquid as necessary, it can be formed by promoting reaction by heating or drying, or solidifying by cooling.

In order to form a thin integrated layer with excellent flexibility, it is desirable that the viscosity of the elastic liquid is 2000 poises or less. In the case of more than this, it is difficult to form a thin film, and it becomes difficult for the liquid material of the elastic body to penetrate into the gap between the conductor wire and the elastic cylindrical body. For forming a thin film, as a liquid material of an elastic body, a two-component mixed reaction type polyurethane elastic body, a polyurethane elastic body dissolved in a solvent, a latex natural rubber elastic body, and a latex synthetic rubber system An elastic body can be used.
By providing the integrated layer of the elastic body, it is possible to prevent the conductor wire and the core material from being displaced due to expansion and contraction, and it is possible to improve practical durability.
The expandable electric wire thus obtained preferably has a resistance of 10 Ω / m or less in a relaxed state. In the case of more than this, even if a weak current can be supplied, it is not suitable for supplying a drive current. More preferably, it is 1 Ω / m or less.

  A thin elastic tape shape incorporating a plurality of the stretchable wires of the present invention can also be made. In order to obtain a narrow elastic tape shape, it is preferable to use 2 to 100 stretchable electric wires that are pre-insulated. Although 3 to 5 general-purpose devices are used, there are cases where it is desired to wire a large number of motors and sensors from a power source to the end with a single tape, and a large number of telescopic wires can be formed into a tape shape. From the viewpoint of handleability, the width of the tape is preferably 20 cm or less, and more preferably 10 cm or less.

EXAMPLES Hereinafter, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited only to these Examples.
The evaluation method used in the present invention is as follows.
(1) 50% elongation recovery rate After leaving the sample in a standard state (temperature 20 ° C, relative humidity 65%) for 2 hours or more, under a standard state, a tensile tester (manufactured by A & D Co., Ltd., Tensilon) Set the sample at a gripping interval of 100 mm on the test machine), stretch at a pulling speed of 100 mm / min, deweight at the same speed immediately after 50% stretching, and the residual when the load becomes zero from the recorded load-extension curve Elongation x (mm) was calculated | required and 50% elongation recovery rate was calculated | required by following Formula.
50% elongation recovery rate (%) = [(50−x) / 50] × 100

(2) 50% elongation stress The same measurement as (1) was performed, and the load P1 (cN) at the time of 50% elongation was determined from the obtained load-elongation curve, and the 50% elongation stress was determined by the following equation.
50% elongation stress (cN / mm ² ) = P1 / A1
A1: A cross-sectional area A (mm ² ) under the standard state of the sample. The cross-sectional area A was determined by measuring the cross-sectional dimensions (diameter in the case of a round cross section and length of each side in the vertical and horizontal directions in the case of a square cross section) with a caliper so that the sample does not deform.
(3) 30% elongation load The same measurement as (1) was performed, and the load (cN) at 30% elongation was determined from the obtained load-elongation curve.

(4) 50% compression stress in the transverse direction After leaving the sample in the standard state (temperature 20 ° C., relative humidity 65%) for 2 hours or more, under the standard state, a compression tester (manufactured by Kato Tech Co., Ltd., handy compression) The sample is placed on the measurement table of the tester, KES-G5) so as to compress the lateral direction of the sample (direction perpendicular to the length direction of the sample). When the pressure plate (diameter 1.6 cm, area 2.0 cm ² ) is slowly lowered and the load reaches 0.5 gf, the pressure plate is stopped, the sample is removed, and GAP measurement is performed. GAP becomes the initial height H1 (mm) of the sample. Next, the sample was placed again under the pressure plate, and the pressure plate was lowered to 50% of the initial height H1 at a speed of 0.1 mm / sec. The load P2 (cN) at the time of 50% compression was determined from the curve, and the 50% compressive stress in the lateral direction was determined from the following equation.
Transverse 50% compressive stress (cN / mm ² ) = P2 / A2
A2 (mm ² ) = Pressure plate diameter × Sample width B1 = 16 × B1
The sample width B1 (mm) is the initial height H1 (m) obtained by GAP measurement in the case of a substantially round cross section.
m), and in the case of a square cross section, a value (mm) obtained by measuring the initial height H1 and the width in the direction perpendicular to the GAP measurement in the same manner as the GAP measurement is used.

(5) Lateral stress at 50% elongation recovery After leaving the sample in the standard state (temperature 20 ° C., relative humidity 65%) for 2 hours or more, under the standard state, compression tester (manufactured by Kato Tech Co., Ltd., A sample is fixed to a measurement table of a handy compression tester (KES-G5) in a state in which the sample is stretched 50% in a direction in which the transverse direction of the sample (direction perpendicular to the length direction of the sample) is compressed. When the pressure plate (diameter 1.6 cm, area 2.0 cm ² ) is slowly lowered and the load reaches 0.5 gf, the pressure plate is stopped, the sample is removed, and GAP measurement is performed. GAP becomes the initial height H2 (mm) of the sample. Next, after placing the sample again under the pressure plate in a state where it is stretched 50%, the sample is relaxed and the load P3 (cN) acting on the pressure plate is read. The lateral stress at the time of 50% elongation recovery was determined by the following equation.
Transverse stress at 50% elongation recovery (cN / mm ² ) = P3 / A3
A3 (mm ² ) = Pressure plate diameter × Sample width at 50% elongation B2 = 16 × B2
The sample width B2 (mm) at 50% elongation is the initial height H2 (mm) obtained by GAP measurement in the case of a substantially round cross section, and the width in the direction perpendicular to the initial height H2 in the case of a square cross section. The value (mm) measured in advance by the same method as the GAP measurement is used.

(6) Repeated elongation recovery property Using a Dematcher type repeated fatigue tester (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), as shown in FIG. 3, the distance between the fixed chuck (11) and the movable chuck (12) is 20 cm. Set the movable length of the chuck (12) to 10 cm and mark the sample (14) marked at 20 cm intervals in a no-load state with the marking position aligned with the lower end of the fixed chuck (11) and the upper end of the movable chuck (12). Hold it. Between the fixed chuck (11) and the movable chuck (12) is a stainless steel rod (13) having a mirror surface with a diameter of 1.27 cm, and 5 cm laterally from the straight line connecting the fixed chuck (11) and the movable chuck (12). Place it overhanging. Under these conditions, the initial elongation is about 11%, and the tensile elongation is about 60%.
At room temperature, after stretching 100,000 times, 200,000 times, 500,000 times and 1,000,000 times at a speed of 60 times / minute, the length L (cm) between the markings of the sample is measured under no load condition. Residual strain was determined by the following equation.
Residual strain (%) = [(L-20) / 20] × 100

(7) Friction durability (electric resistance value change rate)
The same test as in (6) was performed, and the electrical resistance value R1 (when 60% stretched) before the test and the electrical resistance value R2 (when 60% stretched) after repeating the expansion and contraction a predetermined number of times were measured using a milliohm high tester 3540 The electrical resistance value change rate was determined by the following equation.
Electrical resistance change rate (%) = [(R2-R1) / R1] × 100
In addition, the electric wire which wound the several conductor wire measured the electrical resistance change rate of each conductor wire, respectively, and computed those average values. Moreover, the electric wire which disconnected even one conductor wire was determined to be a disconnection.

[Example 1]
Using a double covering machine (made by Kataoka Techno Co., Ltd., SP-400 type), with 940 dtex / 72f polyurethane elastic long fiber (made by Asahi Kasei Fibers Co., Ltd., trade name: Leuka) as a core, while stretching at a stretch ratio of 6 times A 155 dtex / 48f nylon false twisted yarn was wound with a 500 T / m twist (S twist) and a 332 T / m twist (Z twist) to obtain a double cover yarn. Using the obtained double cover yarn, braiding is performed using an eight-placing cord making machine (manufactured by Kokubun Co., Ltd.), and a core material having a substantially round cross section having a diameter of 1.9 mm made of a braid of polyurethane elastic long fibers. Got. Table 1 shows the evaluation results of 50% elongation recovery rate, 50% elongation stress, 50% compressive stress in the transverse direction and transverse stress at the time of 50% elongation recovery of the obtained core material.
Using the obtained core material as a core, a 16-strand stringing machine (manufactured by Kokubun Co., Ltd.) was used to expand the core material 2.0 times, and in the Z direction a copper fine wire assembly line (diameter 0) .03 mm x 90) 2 (arranged diagonally) and 6 nylon false twisted yarns (220 dtex / 72f), 8 ester false twisted yarns (56 dtex / 24f) in the S direction and braided A telescopic wire intermediate was obtained. Using the obtained stretchable electric wire intermediate as a core, it is again placed on a 16-placing machine and stretched 1.8 times, while each of the eight ester false twisted yarns (167 dtex / 72f) in the Z and S directions. Arrangement and external coating by braiding were performed to obtain an expandable electric wire having two conductor wires. Table 1 shows the evaluation results of 30% elongation load, residual strain, and friction durability (electric resistance value change rate) of the obtained stretchable wires.

[Example 2]
The double cover yarn used in Example 1 was knitted using a table knitting machine (10 gauge, 4 pieces, manufactured by Sakurai Textile Machinery Co., Ltd.), and a diameter formed of a knitted string of polyurethane elastic long fibers. A core material having a substantially round cross section of 2.1 mm was obtained. Table 1 shows the evaluation results of 50% elongation recovery rate, 50% elongation stress, 50% compressive stress in the transverse direction and transverse stress at the time of 50% elongation recovery of the obtained core material.
Using the obtained core material as a core, an expandable electric wire was prepared in the same manner as in Example 1. Table 1 shows the evaluation results of 30% elongation load, residual strain, and friction durability (electric resistance value change rate) of the obtained stretchable wires.

[Example 3]
Nylon false twisted yarn (220 dtex / 72f) was made into Z using an eight-punch stringing machine while stretching 3.2 times with the core of six double-cover yarns used in Example 1 aligned. Four braids were arranged in each of the direction and the S direction, and braiding was performed to obtain a core material having a substantially round cross section with a diameter of 2.6 mm. Table 1 shows the evaluation results of 50% elongation recovery rate, 50% elongation stress, 50% compressive stress in the transverse direction and transverse stress at the time of 50% elongation recovery of the obtained core material.
Using the obtained core material as a core, an expandable electric wire was prepared in the same manner as in Example 1. Table 1 shows the evaluation results of 30% elongation load, residual strain, and friction durability (electric resistance value change rate) of the obtained stretchable wires.

[Example 4]
A sheet made of foamable rubber (product name: EPT SEALER, manufactured by Nitto Denko Corporation) mixed with ethylene-propylene-diene rubber (EPDM) with a foaming agent is slit, and a square cross section made of a porous elastic body with a side of 2 mm. The core material was obtained. Table 1 shows the evaluation results of 50% elongation recovery rate, 50% elongation stress, 50% compressive stress in the transverse direction and transverse stress at the time of 50% elongation recovery of the obtained core material.
Using the obtained core material as a core, an expandable electric wire was prepared in the same manner as in Example 1. Table 1 shows the evaluation results of 30% elongation load, residual strain, and friction durability (electric resistance value change rate) of the obtained stretchable wires.

[Example 5]
Add silicone peroxide vulcanizing agent of 0.8 parts to 100 parts of silicone rubber, then knead at room temperature using two rolls to create silicone rubber raw material And extruded with a silicone rubber extruder and stretched at a molding speed of 70 m / min while pre-curing at a vulcanization temperature of 420 ° C. to form a hollow fiber shape having an outer diameter of 2.2 mm and an inner diameter of 1.3 mm. A core material made of an elastic body was obtained. Table 1 shows the evaluation results of 50% elongation recovery rate, 50% elongation stress, 50% compressive stress in the transverse direction and transverse stress at the time of 50% elongation recovery of the obtained core material.
Using the obtained core material as a core, an expandable electric wire was prepared in the same manner as in Example 1. Table 1 shows the evaluation results of 30% elongation load, residual strain, and friction durability (electric resistance value change rate) of the obtained stretchable wires.

[Example 6]
Using the core material obtained in the same manner as in Example 1, using a double covering machine, the core material was stretched 2.0 times, and the copper wire assembly line (diameter 0.03 mm × 90) in the Z direction. Two wires were wound to obtain an elastic wire intermediate. Using the obtained stretchable electric wire intermediate as a core, it is placed on a 16-placing stringing machine and stretched 1.8 times, while each of the eight ester false twisted yarns (167 dtex / 72f) in the Z direction and S direction. Arrangement and external coating by braiding were performed to obtain an expandable electric wire having two conductor wires. Table 1 shows the evaluation results of 30% elongation load, residual strain, and friction durability (electric resistance value change rate) of the obtained stretchable wires.

[Comparative Example 1]
An expandable electric wire was prepared in the same manner as in Example 1 except that a 12th natural rubber thread (square cross section with one side of 2.1 mm) was used as the core material. Obtained 50% elongation recovery rate of core material, 50% elongation stress, lateral 50% compression stress, lateral stress at 50% elongation recovery, 30% elongation load, residual strain and friction of the obtained stretchable wire Table 1 shows the evaluation results of durability (electrical resistance value change rate).

[Comparative Example 2]
Using a double covering machine, 940 dtex / 72f nylon elastic long fiber (Asahi Kasei Fibers Co., Ltd., trade name: leuca) is drawn into a core and stretched at a stretch ratio of 6 times, while 155 dtex / 48f nylon A false twisted yarn is wound with a lower twist of 250 T / m (S twist) and an upper twist of 140 T / m (Z twist), and a core material having a substantially round cross section having a diameter of 1.7 mm made of a double cover yarn of polyurethane elastic long fibers. Obtained. Table 1 shows the evaluation results of 50% elongation recovery rate, 50% elongation stress, 50% compressive stress in the transverse direction and transverse stress at the time of 50% elongation recovery of the obtained core material.
Using the obtained core material as a core, an expandable electric wire was prepared in the same manner as in Example 1. Table 1 shows the evaluation results of 30% elongation load, residual strain, and friction durability (electric resistance value change rate) of the obtained stretchable wires.

[Comparative Example 3]
Using an ester false twisted yarn (333 dtex / 144f), braiding was performed using a 16-punch cord making machine to obtain a core material with a substantially round cross section having a diameter of 2.0 mm made of a braid of ester false twisted yarn. Table 1 shows the evaluation results of 50% elongation recovery rate, 50% elongation stress, 50% compressive stress in the transverse direction and transverse stress at the time of 50% elongation recovery of the obtained core material. In addition, since the 50% elongation stress of the core material is too high, it was difficult to elongate 50% and fix it to the compression tester. Therefore, the lateral stress at the time of 50% elongation recovery in the lateral direction cannot be evaluated. there were.
Using the obtained core material as a core, an expandable electric wire was prepared in the same manner as in Example 1 except that the core material had an expansion ratio of 1.3 times and the expandable electric wire intermediate had an expansion ratio of 1.2. Table 1 shows the evaluation results of 30% elongation load, residual strain, and friction durability (electric resistance value change rate) of the obtained stretchable wires.

Each of the expandable electric wires of the examples had a small load when extended by 30% and could be expanded and contracted with a small force. Further, the residual strain due to repeated expansion and contraction was small, and the elongation recovery property was excellent. Furthermore, as shown in FIG. 1, since the conductor wire has a structure wound in a state of being appropriately buried in the core material, even if the surface of the expandable electric wire is repeatedly subjected to the friction action, the electric resistance value is increased. From the fact that there are few, it can be seen that the conductor wire is less likely to break and has excellent friction durability.
The expandable electric wire of Comparative Example 1 can be expanded and contracted with a small force and is excellent in stretch recovery. However, since the lateral compressive stress of the core material is too high, the conductor wire is the core material as shown in FIG. The structure was wound and protruded from the surface, and the friction durability was inferior.

Although the stretchable electric wire of Comparative Example 2 is excellent in stretch recovery, a large force is required to stretch the wire because the elongation stress of the core material is too high, and the core material is compressed in the lateral direction. Since the stress was too high, the conductor wire protruded from the surface of the core material as shown in FIG. 2, and the friction durability was inferior.
Since the expandable electric wire of Comparative Example 3 has remarkably low core material extensibility, elongation recovery property, and lateral compressive stress, the obtained elastic wire has extremely low extensibility and elongation recovery property, and the friction durability is greatly inferior. It was a thing.

  The expandable electric wire of the present invention is suitable for wiring of devices having bending portions such as bending devices such as body wearing devices and clothes wearing devices in the robot field, and particularly, humanoid robots (internal wiring and skin wiring). It is suitable for power assist devices, wearable electronic devices and the like. Other robots (industrial robots, home robots, hobby robots, etc.), rehabilitation aids, vital data measurement equipment, motion capture, protective clothing with electronic equipment, game controllers (including human-mounted type), microphones, It can be suitably used in the field of headphones and the like.

It is a schematic diagram showing the positional relationship of the core material and conductor wire of the expansion-contraction electric wire of this invention. It is a schematic diagram showing the positional relationship of the core material and conductor wire of the expansion-contraction electric wire of the comparative examples 1 and 2 of this invention. It is a schematic diagram of the evaluation apparatus for repeated elongation recovery and friction durability of the present invention.

Explanation of symbols

1 Core Material 2 Conductor Wire 11 Fixed Chuck 12 Movable Chuck 13 Stainless Bar 14 Sample

Claims (6)

In an expandable electric wire in which a conductor wire is wound around a core material made of an elastic material having elasticity, the core material has a 50% elongation recovery rate of 85 % or more, and a lateral stress at the time of 50% elongation recovery is zero. 0.1 to 5 cN / mm ² and a 50% compressive stress in the lateral direction is 10 to 90 cN / mm ² . The expandable electric wire according to claim 1, wherein the core material has a 50% elongation stress of 5 to 100 cN / mm ² .   The expandable electric wire according to claim 1, wherein the core material is a porous elastic body.   The expandable electric wire according to any one of claims 1 to 3, wherein the core material is an elastic body having at least one hollow portion continuous in the longitudinal direction.   The stretchable electric wire according to any one of claims 1 to 4, wherein the core material is a knitted or braided string made of elastic long fibers.   The stretchable electric wire according to any one of claims 1 to 5, wherein the stretchable electric wire has a covering portion on an outer periphery thereof.

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