Insulated wire
By twisting soft aluminum wire strands in layers with a pitch multiplier of 18 or less, the composite stranded wire design addresses flattening and uneven thickness issues, enhancing flexibility and material efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- PROTERIAL LTD
- Filing Date
- 2026-04-22
- Publication Date
- 2026-06-25
AI Technical Summary
Composite stranded wires composed of soft aluminum wire are prone to flattening, leading to uneven thickness of the insulator, which can result in overuse of insulator material and increased outer diameter of the wire.
A composite stranded wire design where multiple bundled strands of soft aluminum wire are twisted together in layers with the same twisting direction, and the pitch multiplier of each layer is 18 or less, ensuring a finer longitudinal pitch to suppress flattening and uneven thickness.
The design effectively suppresses flattening of the composite stranded wire and unevenness of the insulator, maintaining flexibility while reducing material usage and outer diameter.
Smart Images
Figure 2026105077000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to insulated wires.
Background Art
[0002] Conventionally, an insulated wire having a composite stranded wire as a conductor and an insulating layer covering the composite stranded wire, and using an aluminum wire as a stranded wire constituting the composite stranded wire is known (see Patent Document 1). Aluminum wire is lighter than copper wire, and soft aluminum wire made of annealed aluminum has excellent flexibility.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] However, a composite stranded wire composed of soft aluminum wire has a characteristic that it is likely to be flattened compared to a composite stranded wire composed of conducting wires, and accordingly, there is a problem that the degree of uneven thickness (unevenness of thickness) of the insulator covering the composite stranded wire increases. The insulator needs to ensure a certain thickness at its thinnest part in consideration of ensuring the performance of the wire such as electrical characteristics. When the degree of uneven thickness of the insulator is large, if the covering is performed so as to ensure the thickness at the thinnest part, the outer diameter of the wire becomes thick, leading to overuse of the insulator material and an increase in the outer diameter of the finished wire.
[0005] An object of the present invention is to provide an insulated wire having a composite stranded wire composed of soft aluminum wire and an insulator covering the periphery thereof, and suppressing flattening of the composite stranded wire and uneven thickness of the insulator accompanying it.
Means for Solving the Problems
[0006] The present invention aims to solve the above problems and provides an insulated wire comprising a composite stranded wire in which a plurality of bundled stranded wires made of soft aluminum wire are twisted together in multiple layers, and an insulator covering the periphery of the composite stranded wire, wherein the twisting direction of the bundled stranded wires in each layer of the composite stranded wire is the same, the pitch multiplier of each layer of the composite stranded wire is 18 or less, and the pitch multiplier is expressed as a multiple of the layer core diameter. [Effects of the Invention]
[0007] According to the present invention, it is possible to provide an insulated electric wire comprising a composite stranded wire made of soft aluminum wire and an insulator covering its periphery, wherein the flattening of the composite stranded wire and the resulting uneven thickness of the insulator are suppressed. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 is a radial cross-sectional view showing an example of the configuration of an insulated wire according to an embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram illustrating the flattening ratio and insulation thickness variation of composite stranded wire. [Modes for carrying out the invention]
[0009] Figure 1 is a radial cross-sectional view showing an example of the configuration of an insulated wire 1 according to an embodiment of the present invention. The insulated wire 1 comprises a composite stranded wire 10 in which a plurality of bundled stranded wires 11 made of soft aluminum wire are twisted together in a single or multi-layer structure, and an insulator 20 covering the composite stranded wire 10. Each bundled stranded wire 11 is a stranded wire in which a plurality of individual wires 12 are twisted together. The individual wires 12 are soft aluminum wires made of annealed aluminum. The annealing conditions for the individual wires 12 are, for example, 400°C for 3 hours. The number of bundled stranded wires 11 included in the composite stranded wire 10, the number of layers of twisting of the bundled stranded wires 11 in the composite stranded wire 10, and the number of individual wires 12 included in each bundled stranded wire 11 are not particularly limited.
[0010] Furthermore, as shown in Figure 1, the composite stranded wire 10 may be covered with a separator tape 30, and the insulator 20 may be provided on the separator tape 30. By using the separator tape 30, it is possible to prevent the insulator 20 from getting into the gaps of the composite stranded wire 10 when the insulator 20 is extruded, which would make it difficult to process the ends of the insulated wire 1. However, if the amount of insulator 20 that gets into the gaps of the composite stranded wire 10 is small, such as when the insulator 20 is formed under conditions where strong pressure is not applied during extrusion molding, the separator tape 30 may not be used.
[0011] Insulated wire 1 can be used, for example, for power wiring in railway vehicles, such as main circuit wiring for powering motors from transformers. As mentioned above, aluminum wire is lighter than copper wire, and soft aluminum wire made from annealed aluminum has excellent flexibility. Therefore, when insulated wire 1 is used as a wire for railway vehicles, the weight of the vehicle can be reduced, and its excellent flexibility makes it suitable for wiring in confined spaces inside the vehicle.
[0012] The insulated electric wire 1 is manufactured by extruding an insulator 20 around a composite stranded wire 10 using an extrusion coating machine. Therefore, when extruding the insulator 20, the greater the degree of flattening of the composite stranded wire 10, the greater the variation in the thickness of the insulator 20 and the greater the degree of uneven thickness. The material of the insulator 20 is not particularly limited, and for example, cross-linked polyethylene can be used.
[0013] The pitch multiplier of each layer of the composite stranded wire 10 is preferably 18 or less. When the pitch multiplier of each layer of the composite stranded wire 10 is 18 or less, the flattening of the composite stranded wire 10 and the resulting uneven thickness of the insulator 20 can be effectively suppressed. This is thought to be because, by making the longitudinal pitch of each layer of the composite stranded wire 10 finer, the twisted structure becomes less susceptible to collapse under lateral pressure received from a direction parallel to the cross-section in Figure 1. In particular, when the number of bundled strands 11 constituting the composite stranded wire 10 is 19 or more, and the number of individual wires 12 constituting each bundled strand 11 is 16 or more, flattening of the composite stranded wire 10 is more likely to occur, so a significant effect can be obtained.
[0014] The flatness ratio of the composite stranded wire 10 is preferably 10% or less, and more preferably 5% or less. However, by setting the pitch multiplier of each layer of the composite stranded wire 10 to 18 or less, it becomes easier to satisfy this preferred flatness ratio even when the number of bundled strands 11 constituting the composite stranded wire 10 and the number of individual wires 12 constituting each bundled strand 11 are large.
[0015] Furthermore, if the longitudinal pitch of each layer of the composite stranded wire 10 is too small, problems such as increased conductor resistance and decreased productivity may occur. Therefore, it is preferable that the pitch multiplier of each layer of the composite stranded wire 10 be 8 or greater.
[0016] Figure 2 is a schematic diagram illustrating the flattening ratio of the composite stranded wire 10 and the thickness variation ratio of the insulator 20. The flattening ratio of the composite stranded wire 10 indicates the degree of flattening of the composite stranded wire 10, and is the ratio of D1-D2 to D1, expressed as a percentage, when the major axis of the flattened composite stranded wire 10 shown in Figure 2 is D1 and the minor axis is D2. The thickness variation ratio of the insulator 20 indicates the degree of unevenness in the thickness of the insulator 20, and is the ratio expressed as a percentage of the minimum thickness T2 to the maximum thickness T1 of the unevenly thicked insulator 20 shown in Figure 2.
[0017] Here, the pitch multiples mentioned above represent the pitch as a multiple of the core diameter of the layer. The pitch is the distance traveled along the axial direction during one rotation of the stranded wire 11 during the twisting process. The core diameter of the layer is the diameter of the circle connecting the centers of all the stranded wires 11 contained in the layer of the composite stranded wire 10, and is equal to the value obtained by subtracting the outer diameter of the stranded wires 11 from the outer diameter of the layer. In other words, the pitch multiple of the nth layer (n is a natural number) of the composite stranded wire 10 can be obtained by dividing the pitch of the stranded wires 11 contained in the nth layer by the core diameter of the nth layer.
[0018] Generally, when the twisting direction is alternated between layers in a multilayer stranded wire, the flattening of the stranded wire can be suppressed compared to when the twisting direction is the same for each layer, but the flexibility is reduced. The insulated wire 1 controls the pitch multiplier of each layer of the composite stranded wire 10, so that even when the twisting direction of the bundled strands 11 in each layer of the composite stranded wire 10 is the same, the flattening of the composite stranded wire 10 can be effectively suppressed without sacrificing the flexibility of the composite stranded wire 10.
[0019] For example, as shown in Figure 1, the multiple stranded wires 11 constituting the composite stranded wire 10 include one stranded wire 11 located in the center (hereinafter referred to as the central stranded wire 11a), six stranded wires 11 arranged in the first layer surrounding the central stranded wire 11a (hereinafter referred to as the first layer stranded wires 11b), and twelve stranded wires 11 arranged in the second layer surrounding the first layer stranded wires 11b (hereinafter referred to as the second layer stranded wires 11c). If the composite stranded wire 10 is composed of 18 stranded wires 11 (hereinafter referred to as the third-layer stranded wire 11d) arranged in the third layer surrounding the second-layer stranded wire 11c, and each composite stranded wire 10 is composed of 34 strands 12 with an outer diameter of 0.45 mm, then the core diameters of the first layer including the first-layer stranded wire 11b, the second layer including the second-layer stranded wire 11c, and the third layer including the third-layer stranded wire 11d will be approximately 5.8, 11.6, and 17.4, respectively.
[0020] Therefore, by setting the pitches of the first layer stranded wire 11b, the second layer stranded wire 11c, and the third layer stranded wire 11d to approximately 100 mm, 140 mm, and 160 mm, respectively, the pitch multiples of the first, second, and third layers become 17.2, 12.1, and 9.2, respectively, which fall within the range of 18 or less mentioned above. Hereinafter, the configuration of this composite stranded wire 10 will be referred to as Configuration Example 1.
[0021] Furthermore, by setting the pitches of the first layer stranded wire 11b, the second layer stranded wire 11c, and the third layer stranded wire 11d to approximately 160 mm, 250 mm, and 305 mm, respectively, the pitch multiples of the first, second, and third layers become 27.6, 21.6, and 17.5, respectively, which fall outside the range of 18 or less mentioned above. Hereinafter, this composite stranded wire 10 configuration will be referred to as Configuration Example 2.
[0022] An insulated wire 1 having the configuration of Configuration Example 1 above and including a composite twisted wire 10 in which the twisting directions of the first-layer stranded wire 11b, the second-layer stranded wire 11c, and the third-layer stranded wire 11d are the same, a separator tape 30, and an insulator 20 was manufactured. As a result, the flatness ratio of the composite twisted wire 10 was 5%, and the eccentricity ratio of the insulator 20 was 69.1% (maximum wall thickness: 3.015 mm, minimum wall thickness: 2.082 mm). Further, an insulated wire 1 having the configuration of Configuration Example 2 above and including a composite twisted wire 10 in which the twisting directions of the first-layer stranded wire 11b, the second-layer stranded wire 11c, and the third-layer stranded wire 11d are the same, a separator tape 30, and an insulator 20 was manufactured. As a result, the flatness ratio of the composite twisted wire 10 was 15%, and the eccentricity ratio of the insulator 20 was 50.4% (maximum wall thickness: 3.941 mm, minimum wall thickness: 1.987 mm). In each case, the pitch of the individual strands 12 in each stranded wire 11 was set to 85 to 95 mm, and the twisting direction of the stranded wire 11 in the composite twisted wire 10 and the twisting direction of the individual strands 12 in the stranded wire 11 were made the same. Also, in the manufacture of each insulated wire 1, after adjusting the cross-sectional shape of the composite twisted wire 10 to circular or substantially circular using a correcting machine, the insulator 20 was coated using an extrusion coating machine. The correcting machine adjusts the cross-sectional shape of the composite twisted wire 10 to circular or substantially circular by applying pressure while moving the composite twisted wire 10 in its longitudinal direction and pushing the outer peripheral surface of the composite twisted wire 10 toward the center of the composite twisted wire 10.
[0023] (Effect of the Embodiment) According to the insulated wire 1 according to the embodiment of the present invention, by controlling the pitch multiple of each layer of the composite twisted wire 10, flattening of the composite twisted wire 10 and accompanying eccentricity of the insulator 20 can be effectively suppressed. Also, according to the insulated wire 1, while making the twisting directions of the stranded wires 11 for each layer in the composite twisted wire 10 the same in order to maintain flexibility, flattening of the composite twisted wire 10 and accompanying eccentricity of the insulator 20 can be suppressed.
[0024] (Summary of the Embodiment) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals and other symbols in the following description are not limited to the components in the claims that are specifically shown in the embodiments.
[0025] [1] An insulated electric wire (1) comprising a composite stranded wire (10) formed by twisting together a plurality of bundled stranded wires (11) made of soft aluminum wire in a single or multi-layer structure, and an insulator (12) covering the composite stranded wire (10), wherein the pitch multiplier of each layer of the composite stranded wire (10) is 18 or less, and the pitch multiplier is expressed as a multiple of the core diameter of the layer.
[0026] [2] The insulated wire (1) described in [1] above, wherein the plurality of stranded wires (11) consist of one central stranded wire (11a), six first-layer stranded wires (11b) arranged around the central stranded wire (11a), twelve second-layer stranded wires (11c) arranged around the first-layer stranded wires (11b), and eighteen third-layer stranded wires (11d) arranged around the second-layer stranded wires (11c).
[0027] [3] The insulated wire (1) described in [1] above, wherein the flattening ratio of the composite stranded wire (10) is 10% or less.
[0028] [4] An insulated wire (1) according to any one of the above [1] to [3], wherein the twisting direction of the bundled strands (11) in each layer of the composite stranded wire (10) is the same.
[0029] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. Furthermore, the embodiments described above do not limit the invention as claimed. It should also be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. [Explanation of Symbols]
[0030] 1. Insulated wire 10 Composite stranded wire 11 Collective stranded wire 11a Center cluster twist 11b 1st layer collective stranded wire 11c 2nd layer collective stranded wire 11d third layer stranded wire 12 strands 20 Insulator
Claims
1. A composite stranded wire in which multiple strands of soft aluminum wire are twisted together in multiple layers, An insulator covering the periphery of the aforementioned composite stranded wire, Equipped with, In the aforementioned composite stranded wire, the twisting direction of each layer of the assembled stranded wire is the same. The pitch multiplier of each layer of the composite stranded wire is 18 or less. The aforementioned pitch multiplier is a representation of the pitch as a multiple of the core diameter. Insulated wire.
2. The aforementioned plurality of stranded wires are composed of one central stranded wire, six first-layer stranded wires arranged around the central stranded wire, twelve second-layer stranded wires arranged around the first-layer stranded wires, and eighteen third-layer stranded wires arranged around the second-layer stranded wires. The insulated wire according to claim 1.
3. The flattening ratio of the aforementioned composite stranded wire is 10% or less. The insulated wire according to claim 1.
4. The flattening ratio of the aforementioned composite stranded wire is 5% or less. The insulated wire according to claim 1.