Manufacturing method of stranded wire

Abstract

To provide a method for manufacturing a stranded wire in which the shape of a hollow portion is stable and the outer shape is elliptical or oval. [Solution] A method for manufacturing a stranded wire (10) comprising: manufacturing a preliminary stranded wire (1) which is composed of two layers, a first preliminary outer layer (2a) and a second preliminary outer layer (2b) provided inside the first preliminary outer layer (2a), with a hollow portion (3) formed inside the second preliminary outer layer; making the number of first preliminary strands (4) which constitute the first preliminary outer layer (2a) the same as the number of second preliminary strands (5) which constitute the second preliminary outer layer (2b); forming a wire material which is a base of the first preliminary strand larger in diameter than that of the wire material which is a base of the second preliminary strand; and pressurizing and deforming a part of the preliminary stranded wire (1) using a die (11) which is divided into two from the outside and has an inner circumferential surface (11c) which is formed into an elliptical or oval shape when closed.

Description

[Technical field]

[0001] The present invention relates to a method for producing a stranded wire. [Background technology]

[0002] In the electric wire market, from the viewpoint of making electric wires and cables thinner, lighter, and more functional, a stranded conductor has been proposed in which a first outer layer is formed by circumferentially arranging first wires so that the cross section is close to circular, and a second outer layer is formed by circumferentially arranging second wires inside the first outer layer, with the inside of the second outer layer being hollow (Patent Document 1).

[0003] In recent years, attention has been focused on the fact that the cooling effect can be improved by circulating cold air or the like through the hollow part of this stranded conductor, and the use of the above stranded conductor as a litz wire for magnet coils in electric vehicles has been considered. When used in magnet coils, it is desirable to make the outer shape of the stranded conductor elliptical or oval.

[0004] On the other hand, for a stranded conductor made of one layer having a hollow portion, it has been proposed to roll the stranded conductor to have an elliptical or oval outer shape (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-158331 A [Patent Document 2] Japanese Patent Application Publication No. 11-111063 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in a rolled state, the conductor tends to stretch in the vertical direction but has poor ductility in the horizontal direction. Therefore, when attempting to deform the outer diameter of a two-layer stranded conductor by roll rolling, problems arise in that twisting due to the twist pitch occurs after rolling, the arrangement of the inner second outer layer becomes disrupted, the wires cross each other, and the hollow portion collapses.

[0007] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a method for producing a stranded wire in which the shape of the hollow portion is stable and the outer shape is elliptical or oval. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a pre-stranded wire that is composed of two layers, a first pre-outer layer and a second pre-outer layer provided inside the first pre-outer layer, a hollow portion is formed inside the second pre-outer layer, the first pre-outer layer is composed of a first pre-outer wire, the second pre-outer layer is composed of a second pre-outer wire, the number of the first pre-outer wires is the same as the number of the second pre-outer wires, and the diameter of the wire material that is the base of the first pre-outer wire is larger than the diameter of the wire material that is the base of the second pre-outer wire, A part of the pre-stranded wire is divided into two parts from the outside, and a die having an inner peripheral surface shape in a closed state that is elliptical or oval is closed and pressed, and then the die is opened. Then, a portion of the pre-stranded wire is moved a predetermined distance in the axial direction, and then a two-part die is closed from the outside and pressure is applied to the portion of the pre-stranded wire, which is a method for manufacturing a twisted wire, characterized by repeating this process.

[0009] Further, the circumferential length of a circle having a radius equal to the average distance from the axis of the pre-stranded wire to the outer edge of each of the first pre-strands may be the same as the circumferential length in a cross section of the die.

[0010] In addition, the outer surface of the first preliminary strand constituting the first preliminary outer layer of the preliminary strand is not compressed and deformed, The stranded wire may have a first outer layer and a second outer layer, and the outer surface of the first strand constituting the first outer layer may not be compressively deformed.

[0011] Furthermore, the number of the first wires and the number of the second wires may each be an even number equal to or greater than six. Effect of the Invention

[0012] According to the present invention, a pre-stranded wire is composed of two layers, a first outer layer and a second outer layer provided inside the first outer layer, and a part of the pre-stranded wire having a hollow part formed inside the second outer layer is pressurized and formed using a die having an inner surface shape that is elliptical or oval when closed. The pre-stranded wire is then moved a predetermined distance in the axial direction, and then the pre-stranded wire is pressurized and formed from the outside using a die that is divided into several parts. This process is repeated, thereby making it possible to prevent the collapse of the hollow part due to twisting of the twisted wire and to stably produce the twisted wire. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a cross-sectional view of a pre-stranded wire used in the first embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of an example of a closed state of a mold used in the first embodiment of the present invention. [Diagram 3] FIG. 4 is a perspective view of another example of a mold used in the first embodiment of the present invention in a closed state. [Figure 4] 1 is a cross-sectional view of an example of a stranded wire according to a first embodiment of the present invention. [Diagram 5] FIG. 4 is a cross-sectional view of another example of the stranded wire according to the first embodiment of the present invention. [Figure 6] FIG. 11 is a cross-sectional view showing an example of a stranded wire according to a third embodiment of the present invention. [Figure 7] FIG. 11 is a cross-sectional view showing another example of the stranded wire according to the third embodiment of the present invention. [Figure 8] FIG. 11 is a cross-sectional view showing another example of the stranded wire according to the third embodiment of the present invention. [Figure 9] FIG. 11 is a cross-sectional view showing another example of the stranded wire according to the third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

[0015] [Example 1] First, the preliminary strand will be described.

[0016] As shown in Fig. 1, the pre-stranded wire 1 is composed of a pre-outer layer 2 consisting of two layers, a first pre-outer layer 2a and a second pre-outer layer 2b arranged inside the first pre-outer layer 2a, and a hollow space 3 is formed inside the second pre-outer layer 2b. Fig. 1 is a cross-sectional view of the pre-stranded wire 1 according to Example 1 of the present invention, cut in a direction perpendicular to the axial direction, and the oblique lines indicating the cross sections of each wire are omitted to avoid complicating the drawing.

[0017] 1, the first preliminary outer layer 2a is formed by arranging 20 first preliminary strands 4 on the same circumference, and the 20 wires that form the 20 first preliminary strands 4 constituting the first preliminary outer layer 2a have a circular cross section and are all made of the same diameter and material. The first preliminary strands 4, 4 adjacent to each other in the circumferential direction about the center of the preliminary strand 1 are arranged so as to abut on each other over the entire axial direction or part of the axial direction.

[0018] 1, the second spare outer layer 2b is formed by arranging 20 second spare strands 5 on the same circumference, and the 20 wires that form the 20 second spare strands 5 constituting the second spare outer layer 2b have a circular cross section and are all made of the same diameter and material. The second spare strands 5, 5 adjacent to each other in the circumferential direction about the center of the spare strand 1 are arranged so as to abut on each other over their entire axial direction or over part of their axial direction.

[0019] The number of the first preparatory strands 4 constituting the first preparatory outer layer 2a is set to be the same as the number of the second preparatory strands 5 constituting the second preparatory outer layer 2b.

[0020] The diameter d1 of the wire material that is the basis of the first preliminary strand 4 that constitutes the first preliminary outer layer 2a is set to be larger than the diameter d2 of the wire material that is the basis of the second preliminary strand 5 that constitutes the second preliminary outer layer 2b.

[0021] In an inner valley portion 6 formed between the outer surfaces of the first spare wires 4 constituting the first spare outer layer 2a, a portion of the outer surface of the second spare wire 5 constituting the second spare outer layer 2b is arranged so as to abut against a portion of the outer surface of the first spare wire 4 over its entire axial direction or over a portion of its axial direction.

[0022] The wire material that forms the basis of the first spare wire 4 that constitutes the first spare outer layer 2a, and the wire material that forms the basis of the second spare wire 5 that constitutes the second spare outer layer 2b can be copper wire such as bare copper wire, oxygen-free copper wire, linear crystal oxygen-free copper wire, single crystal high-purity oxygen-free copper wire, copper wire plated with tin, nickel, silver, etc., aluminum wire, various alloy wires, and wires with an insulating coating such as enameled wire, Litz wire, and formal wire.

[0023] In the present embodiment 1, the preparatory strands 4 and 5 for which the relationship d2=0.76×d1 is satisfied were used.

[0024] The cross-sectional shape of the pre-stranded wire 1 is formed to be substantially circular, that is, the distance from the center of the pre-stranded wire 1 to the outermost edge of each of the first pre-stranded strands 4 constituting the first pre-outer layer 2a is substantially the same. The outer shape of the pre-stranded wire 1 can be made substantially circular without compression, and the pre-stranded strands 4, 5 can be in contact with substantially all of the adjacent pre-stranded strands 4, 5. The outer shape of the pre-stranded wire 1 can be made substantially circular without compression.

[0025] Next, a method for producing the stranded wire 10 will be described.

[0026] In manufacturing the stranded wire 10, a mold 11 divided into a plurality of molds 11a, 11b is used as shown in Figs.

[0027] The molds 11a and 11b in this embodiment can be moved in the vertical direction in FIGS. 2 and 3 by a driving means (not shown), and can be moved closer to or farther away from each other.

[0028] When the die 11 is closed as shown in Figures 2 and 3, the shape of its inner circumferential surface 11c is formed into an ellipse as shown in Figure 2, or an oval shape as shown in Figure 3. It is preferable that the perimeter (2 x π x L1) of a circle (two-dot chain line in Figure 1) whose radius is the average of the distances L1 from the axis of the pre-stranded wire 1 to the outer edges of the first pre-strands 4 is the same as the perimeter of the ellipse or oval shape in the cross section of the die.

[0029] The axial length of the die 11 is preferably 5 to 20 times the twist pitch of the pre-stranded wire 1, and in this embodiment it was 10 times.

[0030] With the die 11 open, the die 11 is positioned outside a portion of the pre-stranded wire 1, and then the dies 11a and 11b are closed while applying pressure to deform a section of the pre-stranded wire 1 by a predetermined length in the axial direction to form the twisted wire 10.

[0031] By this pressurization, the first preparatory strand 4 becomes the first strand 14, the first preparatory outer layer 2a becomes the first outer layer 12a, the second preparatory strand 5 becomes the second strand 15, and the second preparatory outer layer 2b becomes the second outer layer 12b. The first outer layer 12a and the second outer layer 12b form the outer layer 12, and the stranded wire 10 has an elliptical or oval outer shape.

[0032] Next, after opening the mold 11, the preliminary stranded wire 1 is moved a predetermined distance in the axial direction so that a part of the stranded wire 10 and a part of the preliminary stranded wire 1 are positioned inside the mold 11, and then the mold is closed while applying pressure to form the stranded wire 10, and the axial length of the formed stranded wire 10 is extended as required.

[0033] This process is repeated to produce the stranded wire 10. The sum of the cross-sectional areas of the wires 14, 15 in the longitudinal section of the stranded wire 10 is set to be the same as the sum of the cross-sectional areas of the preparatory wires 4, 5 in the longitudinal section of the preliminary stranded wire 1. More preferably, the cross-sectional areas of the wires 14, 15 are the same as the cross-sectional areas of the preparatory wires 4, 5. By setting in this manner, the preliminary stranded wire 1 does not stretch in the axial direction when the stranded wire 10 is molded by the die 11, and therefore there is no need to accommodate the axial stretch of the stranded wire 10, and the stranded wire 10 can be stably produced.

[0034] As shown in FIG. 4, the outer surface of the first wire 14 may be formed using a mold 11 so as not to be compressively deformed, or as shown in FIG. 5, the outer surface of the first wire 14 may be formed using dies 11a and 11b so as to be compressively deformed. However, in order to improve the physical properties, flexibility, etc. of the twisted wire 10, it is preferable to prevent the first wire 14 from being compressively deformed as much as possible.

[0035] The first wires 14 constituting the first outer layer 12a of the stranded wire 10 are arranged in an elliptical shape, and the first wires 14, 14 adjacent to each other in the circumferential direction may be in contact with each other or may be spaced apart. Even if the first wires 14, 14 are spaced apart from each other, the shape of the stranded wire 10 is stable because it is twisted and the second wires 15 are located on the inside.

[0036] The second wires 15 constituting the second outer layer 12b of the stranded wire 10 are arranged in an elliptical shape without crossing or intersecting, and the second wires 15, 15 adjacent to each other in the circumferential direction abut each other along their entire axial direction or along part of their axial direction.

[0037] A single first wire 14 is positioned in an outer valley portion 16 formed by the outer surfaces of circumferentially adjacent second wires 15, 15, and in the outer valley portion 16, a portion of the outer surface of the first wire 14 abuts against a portion of the outer surface of the second wire 15 over its entire axial direction or over part of its axial direction.

[0038] A hollow portion 13 is formed inside the twelfth outer layer.

[0039] The shape of the inner peripheral surface of the die 11 is designed so that the perimeter (2×π×L1) of a circle whose radius is the average of the distances L1 from the center to the outer edge of each of the first preparatory strands 4 in the preparatory strand 1 is the same as the perimeter of the ellipse or oval shape in the cross section of the die. In addition, the design is based on the outer diameter of the preparatory strand 1, the inner diameter of the hollow portion 3, the diameters of the preparatory strands 4 and 5, whether the hollow portion 13 of the stranded wire 10 can be formed when molded, its shape, whether the sum of the cross-sectional areas of the strands 14 and 15 in the longitudinal section of the stranded wire 10 is the same as the sum of the cross-sectional areas of the preparatory strands 4 and 5 in the longitudinal section of the preparatory strand 1, etc.

[0040] The stranded wire 10 can improve cooling efficiency by circulating cold air or the like inside the hollow portion 13, and can be used as a Litz wire for magnet coils in electric vehicles by making the outer diameter elliptical or oval. The stranded wire 10 can also be used as a stranded conductor used in electric wires and cables, catheter tubes used in treatment, guide wires passed through blood vessels, medical wires such as operating wires for endoscopes, and the like.

[0041] In the production of the twisted wire 10 using the die 11, the pre-twisted wire 1 has good malleability in the longitudinal and transverse directions, and the twisted wire 10 can be stably produced. Since no rotational force is applied as in the molding by rolling, collapse of the hollow portion 13 due to twisting of the twisted wire 10 can be prevented, and the twisted wire 10 can be stably produced.

[0042] Even in a large-diameter wire having 20 first wires 14 as in this Example 1, the second wires 15 constituting the second outer layer 12b are arranged in an elliptical shape without crossing or intersecting, and circumferentially adjacent second wires 15, 15 abut over their entire axial direction or part of their axial direction. One first wire 14 is located in an outer valley portion 16 formed by the outer surfaces of circumferentially adjacent second wires 15, 15. This makes it possible to make the shape of the second outer layer 12b robust despite having a hollow portion 13, and to stabilize the shape of the twisted wire 10.

[0043] Even when a hard material is used for the wires 14, 15 constituting the stranded wire 10, the presence of the hollow portion 13 allows the stranded wire 10 to have excellent flexibility.

[0044] The outer surface of the first preparatory strand 4 that constitutes the preparatory strand 1 is made of a material that does not undergo compressive deformation, and the perimeter (2 × π × L1) of a circle in the preparatory strand 1 whose radius is the average of the distances L1 from the center to the outer edge of each of the first preparatory strands 4 is made the same as the perimeter of the elliptical or oval shape in the cross section of the mold. This makes it possible to form the outer surface of the first preparatory strand 4 that constitutes the preparatory strand 1 without compressive deformation, and to form the outer surface of the first strand 14 that constitutes the stranded wire 10 without compressive deformation, and the stranded wire 10 can be formed without compromising the physical properties, flexibility, etc. of the strands 14, 15 of the stranded wire 10.

[0045] [Example 2] As long as it is possible to form an arrangement similar to that of the pre-stranded wire 1 of the above-mentioned Example 1, the pre-stranded wire 1 can be formed using wires having any diameter other than the wires having the diameter described in the above-mentioned Example 1. In addition, the pre-stranded wire 1 may be compressed from the outside of the first preliminary outer layer 2a, which is located on the outermost side, by a compression die or the like.

[0046] This compression causes the outer periphery of the first preparatory strand 4 constituting the first preparatory outer layer 2a to be compressed and deformed, so that the outer shape of the preparatory strand 1 can be made closer to a perfect circle. Compression using a compression die or the like may be performed when producing the preparatory strand 1, or may be performed after producing the preparatory strand 1. The compression ratio may be set arbitrarily.

[0047] The other structure is similar to that of the first embodiment, and therefore the description will be omitted.

[0048] In the second embodiment as well, the same effects as those in the first embodiment can be achieved.

[0049] [Example 3] In the above-mentioned Examples 1 and 2, the twisted wire 10 was composed of 20 first wires 14 and 20 second wires 15 each. However, the number of the first wires 14 and the second wires 15 can be set to any number. However, it is preferable to compose the first wires 14 and the second wires 15 with an even number of six or more each.

[0050] The first wires 14 and the second wires 15 are arranged with the same regularity as in the above-mentioned Examples 1 and 2, and the stranded wire is manufactured by the same manufacturing method. In this example as well, it is preferable to form the die so that the perimeter of a circle whose radius is the average of the distances from the center to the outer edge of each of the first preparatory wires in the preparatory strand is the same as the perimeter of the ellipse or oval shape in the cross section of the die.

[0051] For example, as shown in FIG. 6, in the case of a stranded wire 21 in which the first strands 14 and the second strands 15 are each an even number of six strands, the stranded wire 21 can be constructed by using wire material that serves as the base for each strand 14, 15 such that the relationship d2 = 0.385 × d1 holds.

[0052] Furthermore, as shown in FIG. 7, in the case of a stranded wire 22 in which the first strands 14 and the second strands 15 are each composed of an even number of eight strands, the stranded wire 22 can be constructed by using wire material that serves as the base for each strand 14, 15 such that the relationship d2 = 0.495 × d1 holds.

[0053] Furthermore, as shown in FIG. 8, in the case of a stranded wire 23 in which the first strands 14 and the second strands 15 are each an even number of 10 strands, the stranded wire 23 can be constructed by using wire material that serves as the base for each strand 14, 15 such that the relationship d2 = 0.575 × d1 holds.

[0054] Furthermore, as shown in FIG. 9, in the case of a stranded wire 24 in which the first wires 14 and the second wires 15 are each composed of an even number of 12 wires, the stranded wire 24 can be constructed by using wire material that serves as the base for each of the wires 14, 15 such that the relationship d2 = 0.63 × d1 holds.

[0055] The other structure is similar to that of the first and second embodiments, and therefore the description thereof will be omitted.

[0056] In the third embodiment as well, the same effects as those in the first and second embodiments can be achieved. [Explanation of symbols]

[0057] 1 Spare Wire 2a First spare outer layer 2b Second spare outer layer 3 Hollow part 4. First spare wire 5 Second spare wire 10 strands 11 Mold

Claims

1. a preliminary stranded wire is manufactured, the preliminary stranded wire being composed of two layers, a first preliminary outer layer and a second preliminary outer layer provided inside the first preliminary outer layer, a hollow portion being formed inside the second preliminary outer layer, the first preliminary outer layer being composed of a first preliminary strand, the second preliminary outer layer being composed of a second preliminary strand, the number of the first preliminary strands being the same as the number of the second preliminary strands, and the diameter of the wire material on which the first preliminary strand is based being larger than the diameter of the wire material on which the second preliminary strand is based; a die in which a part of the pre-stranded wire is divided into two from the outside and the inner peripheral surface shape in a closed state is elliptical or oval, is closed and pressed, and then the die is opened; Then, a portion of the pre-stranded wire is moved a predetermined distance in the axial direction, and then the portion of the pre-stranded wire is subjected to pressure from the outside while a two-part die is closed, which is a repeating process.

2. 2. The method for manufacturing a stranded wire according to claim 1, wherein a circumferential length of a circle having a radius equal to an average distance from an axis center to an outer edge of each of the first preparatory strands in the preparatory strand is equal to a circumferential length in a cross section of the die.

3. The outer surface of the first preliminary strand constituting the first preliminary outer layer of the preliminary strand is not compressively deformed, 3. The method for producing a stranded wire according to claim 1, wherein the stranded wire has a first outer layer and a second outer layer, and an outer surface of a first wire constituting the first outer layer is not compressed and deformed.

4. 3. The method for manufacturing a stranded wire according to claim 1, wherein the number of the first preparatory strands and the number of the second preparatory strands are each an even number of six or more.

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