Buckling-resistant heating wire

Abstract

The utility model provides a buckling-resistant heating wire. The buckling-resistant heating wire is excellent in buckling resistance, and the possibility of wire breakage can be reduced even when the heating wire is used in a state that the heating wire is always bent. This buckling-resistant heating wire is provided with: a twisted core (11) containing fibers; a twisted conductor (14) formed by twisting a plurality of metal wires (12) provided on the outer periphery of the twisted core (11); and an insulator (16) that is provided on the outer periphery of the stranded conductor (14), and that forms a gap (20) between at least two of the metal wires (12) constituting the stranded conductor (14).

Description

Technical Field

[0001] This utility model relates to a heating wire with flexural durability. Background Technology

[0002] Previously, a structure was proposed to heat the seat belts installed in vehicles such as cars, airplanes, and ships using heating wires.

[0003] For example, Patent Document 1 (Japanese Patent Application Publication No. 2017-81510) discloses a structure for heating a seat belt by energizing a conductive wire woven into the seat belt. However, Patent Document 1 does not disclose the structure of the conductive wire itself.

[0004] In addition, Patent Document 2 (Japanese Patent Application Publication No. 2021-068576) discloses an insulated wire used for automotive wiring, wherein a stranded wire composed of multiple metal single wires is arranged around the stranded core.

[0005] When heating wires are used in situations where they are constantly bent, such as in seat belts, poor flexural strength can lead to wire breakage, thus presenting a challenge of finding heating wires with excellent flexural strength. Utility Model Content

[0006] Therefore, this invention was made to solve the above-mentioned problems, and its purpose is to provide a heating wire with excellent flexural resistance that can reduce the possibility of wire breakage even when used in a constantly bent state.

[0007] To achieve the above objectives, this utility model has the following structure.

[0008] That is, the flexural heating wire according to the present invention is characterized in that the flexural heating wire has: a stranded core comprising fiber filaments; a stranded conductor formed by stranding multiple metal single wires disposed on the outer periphery of the stranded core; and an insulator disposed on the outer periphery of the stranded conductor, wherein at least any two of the metal single wires constituting the stranded conductor form a gap between each other.

[0009] According to this structure, even when the bending-resistant heating wire is bent, the metal wires can be prevented from breaking by passing through the gaps between them without applying stress to the metal wires.

[0010] In addition, the characteristic is that one or more of the gaps are formed in the same cross-section.

[0011] In addition, the void ratio is characterized by being 10% or more and 50% or less.

[0012] If the porosity is less than 10%, the possibility of applying stress to the metal wire increases when the bending heating wire is bent. If the porosity exceeds 50%, the structure becomes unstable and it is difficult to maintain the outer diameter accuracy of the bending heating wire. Therefore, the porosity is preferably 10% or more and 50% or less.

[0013] In addition, the outer diameter of each of the metal single wires is 0.02 mm or more and 0.06 mm or less.

[0014] If the outer diameter of the metal wire is less than 0.02 mm, the possibility of breakage increases; if the outer diameter exceeds 0.06 mm, the flexibility decreases. Therefore, the outer diameter of the metal wire is preferably between 0.02 mm and 0.06 mm.

[0015] In addition, the stranded conductor has a stranding pitch of 5 mm or more and 15 mm or less.

[0016] If the stranding pitch is less than 5 mm, the metal wires are tightly packed together, resulting in a low porosity. This increases the likelihood of stress being applied to the metal wires when the bending heating wire is bent. If the stranding pitch exceeds 15 mm, the porosity becomes too high, the structure becomes unstable, and it is difficult to maintain the outer diameter accuracy of the bending heating wire. Therefore, the stranding pitch of the stranded conductor is preferably 5 mm or more and 15 mm or less.

[0017] In addition, the outer diameter of the flexural heating wire is 0.25 mm or more and 0.5 mm or less.

[0018] For example, in the aforementioned Patent Document 2, only embodiments with an outer diameter of 1 mm or more are disclosed, which are therefore difficult to weave into thin raw materials such as seat belts. However, according to this structure, it is possible to weave it into seat belts and the like for use.

[0019] The flexural heating wire of this invention reduces the possibility of wire breakage even when used in a constantly bent state. Attached Figure Description

[0020] Figure 1 This is an explanatory diagram showing the structure of the flexural heating wire of this embodiment from the side.

[0021] Figure 2 This is a cross-sectional view showing the same cross-section of the flexural heating wire of this embodiment.

[0022] Figure 3 This is a cross-sectional view of the same cross section showing other embodiments of the flexural heating wire.

[0023] Figure 4This is a cross-sectional view of the same cross section showing other embodiments of the flexural heating wire.

[0024] Figure 5 This is an explanatory diagram of the buckling durability test apparatus.

[0025] Figure 6A This is an illustration showing the use of a buckling durability testing apparatus to rotate one end of the buckling heating wire 90 degrees to the left.

[0026] Figure 6B This is an illustration showing the use of a buckling durability testing apparatus to rotate one end of the buckling heating wire 90 degrees to the right. Detailed Implementation

[0027] Hereinafter, preferred embodiments of the flexural heating wire will be described in detail with reference to the accompanying drawings.

[0028] (Flexibility-resistant heating wire)

[0029] like Figures 1-2 As shown, the flexural heating wire 10 includes: a stranded core 11 comprising fiber filaments; a stranded conductor 14 formed by stranding multiple metal single wires 12 disposed on the outer periphery of the stranded core 11; and an insulator 16 disposed on the outer periphery of the stranded conductor 14. However, a coiled film may be disposed between the stranded conductor 14 and the insulator 16, and a plating layer or an insulating coating layer may be disposed on the surface of each metal single wire 12.

[0030] In the flexural heating wire 10, at least any two of the multiple metal wires 12 constituting the stranded conductor 14 have gaps 20 between them.

[0031] exist Figure 2 In the illustrated embodiment, six metal wires 12 constituting the stranded conductor 14 are evenly arranged on the outer periphery of the stranded core 11, with six gaps 20 formed between each other. In other words, the six metal wires 12 are arranged in a state where they do not contact each other.

[0032] By forming gaps 20 between the metal wires 12, even when the bending-resistant heating wire 10 is bent, stress can be applied to the metal wires 12 through the gaps 20 between them, thereby preventing the metal wires 12 from breaking and making it a heating wire with high bending resistance.

[0033] Figure 3 Other embodiments of the flexural heating wire with voids are shown.

[0034] exist Figure 3In the illustrated embodiment, eight metal wires 12 constituting the stranded conductor 14 are unevenly arranged on the outer periphery of the stranded core 11, and a gap 20 is formed between two of the eight metal wires 12, 12a and 12h. Since no gap 20 is formed between the metal wires 12 other than 12a and 12h, therefore... Figure 3 In the embodiment shown, a gap 20 is formed within the flexural heating wire 10.

[0035] Thus, even in an embodiment where only one gap 20 is formed, when the bending-resistant heating wire 10 bends, stress can be applied to the metal single wire 12 through the gap 20, thereby preventing the metal single wire 12 from breaking and making it a heating wire with high bending resistance.

[0036] Figure 4 Other embodiments of the flexural heating wire with voids are shown.

[0037] exist Figure 4 In the embodiment shown, eight metal wires 12 constituting the stranded conductor 14 are unevenly arranged on the outer periphery of the stranded core 11. A gap 20 is formed between two metal wires 12a and 12b, between two metal wires 12c and 12d, between two metal wires 12f and 12g, between two metal wires 12g and 12h, and between two metal wires 12h and 12a.

[0038] Thus, even in embodiments with multiple gaps 20, when the bending-resistant heating wire 10 bends, stress can be applied to the metal single wire 12 through the gaps 20, thereby preventing the metal single wire 12 from breaking and making it a heating wire with high bending resistance.

[0039] As mentioned above, the location where the gap 20 is formed can be any location as long as it is between at least any two metal wires 12, as long as at least one gap 20 is formed.

[0040] The porosity of the void 20 is preferably 10% or more and 50% or less.

[0041] This is because if the porosity is less than 10%, the possibility of applying stress to the metal wire increases when the bending heating wire is bent. If the porosity exceeds 50%, the structure becomes unstable and it is difficult to maintain the outer diameter accuracy of the bending heating wire.

[0042] Furthermore, in the embodiments described above, a space is formed between the stranded core 11 and the insulator 16 such that only one metal wire 12 constituting the stranded conductor 14 is disposed. That is, in the same cross-section, on the outer periphery of the stranded core 11, the metal wire 12 constituting the stranded conductor 14 is disposed in a single layer between the core 11 and the insulator 16, and the metal wires 12 do not overlap in the radial direction.

[0043] In this way, by ensuring that the metal single wires 12 do not overlap radially on the outer periphery of the stranded core 11, the stress applied to the metal single wires 12 can be reduced, thereby preventing the metal single wires 12 from breaking and making it a heating wire with high bending resistance.

[0044] The following is an explanation of the components of the flexural heating wire.

[0045] (Stranded core)

[0046] The stranded core 11 is positioned at the center of the cross-section of the flexural heating wire 10, serving as the core. The stranded core 11 is formed by twisting together multiple fiber filaments (not shown). As fiber filaments, they need strength and heat resistance to function as the core. Such fiber filaments can be, for example, polyester fibers, polyaramid fibers, or aramid fibers.

[0047] In addition, the fibers constituting the stranded core 11 can be fibers of the same material, fibers of different materials, or fibers formed by arbitrarily combining fibers with different outer diameters.

[0048] Furthermore, when using the flexural heating wire 10 in applications requiring high tension, the stranded core 11 may include metal wires (not shown). In this case, in addition to the multiple filaments constituting the stranded core 11, it also includes fewer metal wires than the number of filaments. For example, tungsten can be used as the metal wire. Alternatively, it may include multiple metal wires of different materials.

[0049] The outer diameter of the stranded core 11 is preferably 0.07 mm or more and 0.15 mm or less. This is because if the outer diameter of the stranded core 11 is less than 0.07 mm, it is difficult to maintain strength, and if it exceeds 0.15 mm, the overall outer diameter of the flexural heating wire 10 becomes too thick and difficult to weave into the thin raw material.

[0050] In addition, the stranded core 11 has a roughly circular cross-section, but it can also be recessed at the point where it contacts the metal single wire 12 of the stranded conductor 14.

[0051] (Stranded conductor)

[0052] The stranded conductor 14 is disposed on the outer periphery of the stranded core 11 and is formed by stranding multiple metal single wires 12 together. The stranded conductor 14 is formed by concentrically stranding around the stranded core 11. In addition, the stranding direction can be right-hand twist (S-twist) or left-hand twist (Z-twist).

[0053] The stranding pitch of the stranded conductor 14 is preferably 5 mm or more and 15 mm or less. This is because if the stranding pitch is less than 5 mm, the metal wires are arranged closely together, resulting in a lower porosity. This increases the likelihood of stress being applied to the metal wires when the bending heating wire is bent. If the stranding pitch exceeds 15 mm, the porosity becomes too high, the structure becomes unstable, and it is difficult to maintain the outer diameter accuracy of the bending heating wire.

[0054] The metal wire 12 constituting the stranded conductor 14 needs to be made of a material with good conductivity and high durability. For example, copper alloys such as copper-silver alloys and copper-tin alloys are preferred as such metal wires 12.

[0055] Alternatively, a plating layer can be applied to the surface of the metal single wire 12. The plating layer can be a solder plating layer, a tin plating layer, a gold plating layer, a silver plating layer, a nickel plating layer, etc.

[0056] Furthermore, an insulating coating can also be applied to the surface of the metal single wire 12. The type of insulating coating is not particularly limited; examples include common enameled films such as urethane, polyester, polyesterimide (PEI), polyimide (PI), and polyamideimide (PAI).

[0057] In addition, the thickness of the insulating film is preferably between 0.003 mm and 0.015 mm.

[0058] The outer diameter of the metal single wire 12 is preferably 0.02 mm or more and 0.06 mm or less. This is because if the outer diameter of the metal single wire 12 is less than 0.02 mm, manufacturing becomes difficult, and if it exceeds 0.06 mm, the bending resistance deteriorates.

[0059] (Insulator)

[0060] The insulator 16 is provided in such a way that it covers the outer periphery of the stranded conductor 14. For example, after the stranded conductor 14 is provided, it can be formed by resin extrusion or the like in such a way that it covers the outer periphery of the stranded conductor 14.

[0061] The insulator 16 can be made of a resin material that is both insulating and heat-resistant. In this embodiment, a resin with heat resistance up to 220°C is used, such as FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (ethylene-tetrafluoroethylene copolymer), PFA (perfluoroalkoxyalkane), etc., which are fluoropolymers.

[0062] In addition, the insulator 16 can also be formed by methods other than resin extrusion. For example, it can also be formed by transversely winding nylon 6.6 fibers or polyarylate fibers.

[0063] The thickness of the insulator 16 is preferably 0.05 mm or more and 0.15 mm or less.

[0064] In addition, the insulator 16 is a single layer rather than a multi-layered one. This is because if the insulator 16 were multi-layered, its flexibility would be poor, making it difficult to use in situations where it is constantly bent, such as in seat belts.

[0065] (Buckling durability test)

[0066] Figure 5 A schematic structure of a buckling durability testing apparatus for performing buckling durability tests on a buckling heating wire is shown.

[0067] The buckling durability testing apparatus 40 includes: two first holding rollers 41 disposed on both sides of the buckling heating wire 10 to hold one end of the buckling heating wire 10; a support portion 42 that supports the two first holding rollers 41 so that they can rotate; a drive device (not shown) that rotates the support portion 42 in a direction perpendicular to the axial direction of the buckling heating wire 10; two second holding rollers 46 that hold the other end of the buckling heating wire 10; and a load portion 48 that applies a load to the other end of the buckling heating wire 10.

[0068] The buckling durability test apparatus 40 can be a structure that holds the buckling heating wire 10 with its axis pointing vertically or with its axis pointing horizontally.

[0069] Furthermore, when the structure holds the bending-resistant heating wire 10 with its axial direction facing the vertical direction, a weight of a specified weight can be used as the load part 48. When the structure holds the bending-resistant heating wire 10 with its axial direction facing the horizontal direction, the load part 48 can be a structure that applies a specified load for traction.

[0070] In addition, in the buckling durability test apparatus 40 of this embodiment, the diameters of the two first holding rollers 41 are 5 mm, and the load size is 100 gf, which serves as the load part 48.

[0071] according to Figure 6A and Figure 6B For those who used Figure 5 The buckling durability test of the buckling durability test apparatus shown will be explained.

[0072] When performing a buckling durability test on the buckling-resistant heating wire 10, one end of the buckling-resistant heating wire 10 is clamped between the first holding rollers 41 of the buckling durability test apparatus 40, and the other end of the buckling-resistant heating wire 10 is clamped between the second holding rollers 46. Furthermore, a load portion 48 is installed at the other end of the buckling-resistant heating wire 10.

[0073] Then, the drive unit (not shown) is activated, such as... Figure 6A As shown, the support portion 42 is rotated 90 degrees to the left from its straight position, centered on an axis perpendicular to the axis of the buckling-resistant heating wire 10 (viewed from the front). Figure 6A (Time), then, as Figure 6B As shown, the support portion 42 is rotated 90 degrees to the right from its straight position with respect to an axis perpendicular to the axis of the buckling-resistant heating wire 10 (viewed from the front). Figure 6B hour).

[0074] That is, in the buckling durability test, the action of repeatedly bending the buckling heating line 10 from a straight state to the left and right by 90 degrees (i.e., the buckling angle is 180 degrees) with the first holding roller 41 as the center is repeatedly performed.

[0075] In addition, the buckling speed is 40 times / minute. The number of buckling cycles is compared between the buckling-resistant heating wire of this embodiment and the conventional heating wire, and the number of buckling cycles until the resistance value of the buckling-resistant heating wire 10 increases by 5%.

[0076] In the flexural heating wire of this embodiment, the outer diameter is 0.38 mm, and at least any two metal wires 12 constituting the stranded conductor 14 have gaps 20 between them.

[0077] In the existing heating wire used as a comparison, the outer diameter is 0.9 mm, and there are no gaps between the metal single wires 12.

[0078] (Experimental Results)

[0079] The results of the above-mentioned buckling durability test show that the buckling resistance heating wire of this embodiment can withstand 70,000 buckling cycles until the resistance value increases by 5%, while the conventional heating wire can withstand 30,000 buckling cycles until the resistance value increases by 5%.

[0080] Therefore, it is clear that although the flexural resistance heating wire of this embodiment can have a finer outer diameter and be woven into a thinner raw material compared with the existing heating wire, it can significantly improve flexural resistance compared with the existing heating wire.

[0081] Furthermore, the flexural heating wire 10 is not limited to use in weaving into seat belts; it can be used for any purpose as long as it is used in a constantly bending condition.

Claims

1. A flexurally resistant heating wire, characterized in that, This flexurally resistant heating wire has the following characteristics: A stranded core, which contains fiber filaments; A stranded conductor, which is composed of multiple single metal wires stranded together and disposed on the outer periphery of the stranded core; and An insulator is disposed on the outer periphery of the stranded conductor. At least two of the metal wires constituting the stranded conductor have gaps between them.

2. The flexural heating wire according to claim 1, characterized in that, One or more gaps are formed in the same cross-section.

3. The flexural heating wire according to claim 1 or 2, characterized in that, The porosity of the void is above 10% and below 50%.

4. The flexural heating wire according to claim 1 or 2, characterized in that, The outer diameter of each of the metal single wires is 0.02 mm or more and 0.06 mm or less.

5. The flexural heating wire according to claim 1 or 2, characterized in that, The stranded conductor has a stranding pitch of 5 mm or more and 15 mm or less.

6. The flexural heating wire according to claim 1 or 2, characterized in that, The outer diameter of the flexural heating wire is above 0.25 mm and below 0.5 mm.

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