JP2019040672A - Enamel wire and production method of enamel wire - Google Patents

Abstract

To provide an enamel wire in which an insulation coating coated on an outer periphery of a flat angle conductor having a cross-section of a flat angle shape having an aspect ratio of 10:1 or more and a length of a minor axis of 0.80 mm or less is difficult to be cracked to edge-wise flexure and a production method of the enamel wire.SOLUTION: An enamel wire of the present invention includes:a flat angle conductor having a cross-section having a ratio between a length a of a major axis and a length b of a minor axis [a/b] of at least 10 and the length b of the minor axis of at most 0.80 mm; and an insulation coating coated on the outer periphery of the flat angle conductor, in which the elongation is 40% or more, the tensile strength is 280 MPa or less, and the 0.2% yield strength is 65 MPa or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an enamel wire used for a coil for an electric device such as a motor or a transformer, and a method for manufacturing the enamel wire.

  As a conventional enameled wire, for example, there is an enameled wire having an insulating film for covering the rectangular conductor on the outer periphery of a rectangular conductor having a rectangular cross section.

  In Patent Document 1, the ratio a / b between the length a of the long axis and the length b of the short axis made of tough pitch copper or oxygen-free copper and having a rectangular cross section is 15 or more, and the length of the short axis b is 0.3 mm to 1.2 mm, chamfers having a radius of curvature of 0.05 mm to 0.60 mm are formed at the corners formed at the four corners of the rectangular cross section, and the arithmetic average roughness Ra of the surface of the corner is 0. 0.05 μm to 0.3 μm, the maximum height Rz is 0.5 μm to 2.5 μm, and the ratio of the root mean square roughness Rq to the maximum height Rz (Rq / Rz) is 0.06 to 1.1. A flat rectangular insulated wire material for a coil is disclosed. Moreover, in patent document 1, when manufacturing the flat insulated wire raw material for coils mentioned above, it replaces with the method of rolling from the conventional round wire, and manufactures a rectangular-shaped conducting wire, it slits and slits which have a rectangular cross section It is said that it is obtained by a manufacturing method in which, after a strip material is produced, a corner portion of a rectangular cross section is formed by drawing.

  And in patent document 1, by applying the above-mentioned flat insulated wire material for coil and its manufacturing method, the curvature radius of the corner of the rectangular cross section is accurately formed, and the flat conducting wire itself is not easily bent or warped. It is said that an enameled wire having a stable resin coating is obtained.

JP 2012-195212 A

  An aspect ratio consisting of the ratio of the length of the long axis to the length of the short axis when the coil is formed by bending the enameled wire in the width direction (long axis direction) of the flat conductor (ie, edgewise bending). The enameled wire having a rectangular conductor having a rectangular cross section with a short axis length of 0.80 mm or less with a short axis length of 10: 1 or more is likely to crack in the insulating film near the top of the curved portion. .

  Therefore, the present invention has been made in view of the above points, and has an object of having a rectangular cross section with an aspect ratio of 10: 1 or more and a minor axis length of 0.80 mm or less. It is an object of the present invention to provide an enameled wire in which an insulating film coated on the outer periphery of a flat conductor is less likely to crack when edgewise bent, and a method for producing the enameled wire.

  In order to achieve the above object, one embodiment of the present invention provides the following enamel wire and a method for producing the enamel wire.

[1] A rectangular cross section in which the ratio “a / b” of the length a of the major axis to the length b of the minor axis is 10 or more and the length b of the minor axis is 0.80 mm or less. An enameled wire comprising a flat conductor and an insulating film coated on the outer periphery of the flat conductor, having an elongation of 40% or more, a tensile strength of 280 MPa or less, and a 0.2% proof stress of 65 MPa or more.
[2] By rolling the wire using a pair of rolling rolls, the ratio “a / b” between the length a of the major axis and the length b of the minor axis is 10 or more, and the length b of the minor axis Including a rolling process for forming a rectangular conductor having a rectangular cross section of 0.80 mm or less, and an insulating film forming process for forming an insulating film covering the outer periphery of the rectangular conductor. In the rolling process, A depth d having a size of 0.20 times or more and less than 0.50 times the length a of the long axis of the flat conductor obtained by rolling on the portion of the rolling roll where the wire rod is rolled; and In relation to the depth d, a groove having a width W satisfying 2 ≦ d / W ≦ 6 is provided, and the wire is rolled by passing the rolling roll so that the wire is in contact with the inner surface of the groove. A method of manufacturing enameled wire.
[3] The enamel according to the above [2], wherein the wire rod is a metal wire rod having a circular cross section that is formed into a flat cross section having a minor axis length of greater than 0.80 mm by extrusion molding. Wire manufacturing method.
[4] In the above [2], the insulating film forming step includes a painting step of painting an insulating paint around the rectangular conductor using a coating die having a protrusion on an inner surface of an opening through which the rectangular conductor is inserted. The manufacturing method of enameled wire as described.

  According to the present invention, an insulating film coated on the outer periphery of a rectangular conductor having a rectangular cross section with an aspect ratio of 10: 1 or more and a minor axis length of 0.80 mm or less is resistant to edgewise bending. Thus, it is possible to provide an enameled wire that is unlikely to crack and a method for producing the enameled wire.

It is a schematic cross-sectional view which shows the structural example of the enamel wire which concerns on one Embodiment of this invention. It is explanatory drawing which shows an example of the flow when manufacturing the enameled wire which concerns on one Embodiment of this invention. In the manufacturing method of the enameled wire which concerns on one Embodiment of this invention, it is a schematic block diagram which shows the rolling roll used when manufacturing a flat conductor by rolling.

<One Embodiment of the Present Invention>
Hereinafter, an enameled wire and an enameled wire manufacturing method according to an embodiment of the present invention will be described with reference to the drawings.

[Enamelled wire]
FIG. 1 is a schematic cross-sectional view illustrating a configuration example of an enameled wire 10 according to the present embodiment.

  As shown in FIG. 1, the enameled wire 10 according to the present embodiment has a ratio “a / b” of a major axis length a to a minor axis length b of 10 or more, and a minor axis length b is 10 or more. A flat conductor 11 having a flat rectangular cross section of 0.80 mm or less, and an insulating film 12 that covers the outer periphery of the flat conductor 11 and insulates the flat conductor 11 are provided. In the enameled wire 10 according to the present embodiment, the rectangular conductor 11 has, for example, a ratio “a / b” between the length of the major axis “a” and the length of the minor axis “b” of 10 to 25, The target is one having a rectangular cross section with a length b of 0.40 mm or more and 0.80 mm or less.

  In the enameled wire 10, the long axis length “a” is the length between the two short sides 111 and 112 of the flat conductor 11 facing each other, and the short axis length “b” is 2 facing the flat conductor 11. It is the length between the two long sides 113 and 114.

  The enameled wire 10 preferably has an elongation percentage of 40% or more in a state where the insulating film 12 is provided on the outer periphery of the rectangular conductor 11. As a result, the enameled wire 10 has a ratio “a / b” between the major axis length “a” and the minor axis length “b” of the flat conductor 11 of 10 or more and the minor axis length “b” of 0.80 mm or less. In some cases, when the enameled wire 10 is bent edgewise (hereinafter, also referred to as “edgewise bending”) at the time of coil forming, the portion of the insulation film 12 that has been bent is bent by edgewise bending. It is possible to make it difficult for cracks to occur in the insulating coating 12) near the top of the portion.

  In addition, the enameled wire 10 according to the present embodiment preferably has a tensile strength of 280 MPa or less, more preferably 230 MPa or more and 280 MPa or less in a state where the insulating film 12 is provided on the outer periphery of the flat conductor 11. Furthermore, the 0.2% proof stress in the state having the insulating film 12 around the rectangular conductor 11 is preferably 65 MPa or more, and more preferably 70 MPa or more and 95 MPa or less. Since the enameled wire 10 has such tensile strength and 0.2% proof stress, the ratio “a / b” between the major axis length “a” and the minor axis length “b” of the flat conductor 11 is 10 or more. In the case where the short axis length b is 0.80 mm or less, the insulating film 12 of the portion subjected to bending with respect to the edgewise bending at the time of coil forming (particularly of the portion curved by the edgewise bending). It is possible to make it difficult for the insulating film 12) near the top to crack.

  Further, in the enameled wire 10 according to the present embodiment, a portion curved by edgewise bending when the coil is formed by edgewise bending by having the above-described specific elongation rate, tensile strength, and 0.2% proof stress. Can be bent without causing a shape that fluctuates in the direction of the short axis (for example, the enameled wire 10 is bent).

  In addition, the elongation rate and tensile strength of the enameled wire 10 can be obtained by a method based on JIS C3216-3. Further, the 0.2% yield strength of the enameled wire 10 is obtained by drawing a tangent to the obtained stress-strain curve from the origin in the stress-strain curve obtained when measuring the above-described elongation rate and tensile strength, and then When a straight line parallel to the tangent line is drawn from a position where the strain is 0.2%, a point (intersection) where the stress-strain curve intersects the straight line is obtained, and the stress at this intersection is defined as 0.2% proof stress. Can be calculated.

(Flat rectangular conductor)
The rectangular conductor 11 has a ratio “a / b” of the major axis length a to the minor axis length b of 10 or more and the minor axis length b of 0.80 mm or less. For example, the rectangular conductor 11 is intended for a conductor having “a / b” of 10 or more and 25 or less and a short axis length b of 0.40 mm or more and 0.80 mm or less. Moreover, it is preferable that the length a of the long axis of the flat conductor 11 is 6 mm or more and 16 mm or less. Furthermore, the flat conductor 11 has a cross section that is curved so that the corners of the four corners have a specific radius of curvature (for example, a radius of curvature of 0.10 mm to 0.60 mm). The flat conductor 11 can be made into a coil having a reduced thickness in the short axis direction when the enameled wire 10 is formed into a coil by having such a shape. Further, the rectangular conductor 11 having such a shape can increase the surface area without reducing the area of the cross section of the rectangular conductor 11 in the enameled wire 10. Therefore, in the enameled wire 10 including the flat conductor 11, the resistance value increase rate in a high frequency region (for example, 100 kHz) can be reduced.

  The rectangular conductor 11 is made of a highly conductive metal, for example, low oxygen copper, oxygen free copper, a copper alloy having conductivity equivalent to these pure copper, or a metal such as aluminum.

(Insulating film)
The insulating film 12 is formed by coating the outer periphery of the flat conductor 11 with an insulating film made of an insulating resin selected from, for example, polyamideimide, polyimide, and polyesterimide. In particular, the insulating film 12 is preferably composed of a resin made of polyamideimide or polyimide from the viewpoint of increasing heat resistance. The insulating film 12 has a thickness of 20 μm or more and 100 μm or less, for example. The thickness of the insulating film 12 can be appropriately adjusted according to changes in characteristics such as withstand voltage.

  In FIG. 1, the insulating film 12 is provided in a single layer on the outer periphery of the flat conductor 11. For example, the first insulating film that covers the outer periphery of the flat conductor 11 and improves the adhesion to the flat conductor 11 is used. It is good also as a 2 layer insulation film 12 which has a film | membrane and the 2nd insulation film which consists of resin mentioned above coat | covered on the outer periphery of this 1st insulation film. By coating the first insulating film for improving the adhesion so as to be in contact with the rectangular conductor 11, the enameled wire 10 is peeled off from the rectangular conductor 11 by the edgewise bending at the time of coil forming. It can be made difficult to break, and it becomes difficult to break. The first insulating film that improves the adhesion is, for example, melamine as an insulating resin selected from polyamide imide, polyimide, and polyester imide from the viewpoint of providing high adhesion while maintaining high insulation. It is comprised with what added the additive which improves adhesiveness, such as a kind.

  Further, the enameled wire 10 may have an insulating film 12 on the outer periphery of the flat conductor 11 and may have another film having lubricity or fusion property on the outer periphery of the insulating film 12.

[Method for producing enameled wire]
Next, the manufacturing method of the enamel wire which concerns on one Embodiment of this invention is demonstrated using FIG. 2, FIG. FIG. 2 is an explanatory diagram showing an example of a flow when manufacturing an enameled wire according to an embodiment of the present invention, and FIG. 3 is a rectangular conductor in the method of manufacturing an enameled wire according to an embodiment of the present invention. It is a schematic block diagram which shows the rolling roll used when manufacturing this by rolling.

  In the enameled wire manufacturing method according to the present embodiment, for example, the flat conductor 11 and the enameled wire 10 described above are manufactured by the flow of the manufacturing method as shown in FIG.

  More specifically, in the method for manufacturing an enameled wire according to the present embodiment, a wire made of a metal wire having a predetermined outer shape is sent from a feeder to a rolling device, and the wire has the rectangular cross section described above by the rolling device. A rolling step of rolling the flat conductor 11 having a coating, a coating step of applying an insulating paint to the outer periphery of the flat conductor 11 obtained by rolling, and a heating step of heating the flat conductor 11 coated with the insulating paint. . And in the manufacturing method of the enameled wire which concerns on this embodiment, by winding up the rectangular wire obtained by performing the rolling process mentioned above, a coating process, and a heating process with a winding machine, the rectangular conductor 11 shown in FIG. The enameled wire 10 having the insulating film 12 on the outer periphery is obtained.

  In addition, each of these processes may be performed on the same production line for a part or all of the processes. Moreover, when performing a rolling process in multiple times, it is preferable to have the annealing process which anneals the flat conductor obtained by rolling between the rolling process of a previous process, and the following process.

  Below, each process mentioned above is explained in full detail.

(Rolling process)
In the rolling process for forming the flat conductor 11, a wire made of a metal wire is rolled by a rolling device. The metal wire used for the wire is made of, for example, low-oxygen copper, oxygen-free copper, a copper alloy having conductivity equivalent to these pure copper, or a metal such as aluminum. When the cross section is circular, the wire has a diameter of about 8 mm to 12 mm. When the metal wire is made of low-oxygen copper, oxygen-free copper, or a copper alloy having the same conductivity as those of pure copper, the metal wire is an annealed copper wire from the viewpoint of ease of rolling the metal wire. Is preferred.

  In this rolling process, as shown in FIG. 3, the length 1 of the long axis and the length b of the short axis are obtained by rolling the wire 1 one or more times using a pair of rolling rolls 131a and 131b included in the rolling device. A rectangular conductor having a rectangular cross section with a ratio “a / b” of 10 or more and a short axis length b of 0.80 mm or less is manufactured. In addition, the length a of the long axis of the flat conductor is 6 mm or more and 16 mm or less. The rectangular conductor has, for example, a ratio “a / b” of a major axis length a to a minor axis length b of 10 to 25 and a minor axis length b of 0.40 mm to 0.80 mm. It has a certain rectangular cross section.

  The rolling rolls 131a and 131b used in the rolling process are provided with grooves 132a and 132b having a specific depth d in a portion where the wire 1 is rolled. As shown in FIG. 3, the wire 1 passes through the inside of the rolling roll so that the wire 1 is in contact with part or all of the inner surfaces of the grooves 132 a and 132 b of the pair of opposing rolling rolls 131 a and 131 b. At this time, the rolling rod 131a, 131b rolls the wire 1 by rotating in the same direction about the shafts 133a, 133b. By performing such a rolling process at least once, preferably at least once and not more than 3 times, the rectangular conductor 11 having the above-described rectangular cross section shown in FIG. 1 is manufactured.

  The depth d of the grooves 132a and 132b is preferably 0.20 times or more and less than 0.50 times the long axis length a of the flat conductor 11 obtained by rolling the wire 1 in the rolling step. For example, the depths of the grooves 132a and 132b are appropriately adjusted in the range of 1.20 mm or more and less than 8.00 mm according to the size of the long axis length a of the flat conductor 11 obtained by rolling. In addition, the magnitude | size of the depth d is the distance from the bottom part of the groove | channels 132a and 132b to the surface 134 of the rolling rolls 131a and 131b. Moreover, it is preferable that the depth d of the groove | channel 132a which the rolling roll 131a has, and the depth d of the groove | channel 132b which the rolling roll 131b has are the same magnitude | sizes.

  In addition to this, it is preferable that the rolling rolls 131a and 131b have such a size that the width W of the grooves 132a and 132b where the wire 1 is rolled satisfies the relationship of 2.00 ≦ d / W ≦ 6.00. The width W of the grooves 132a and 132b is, for example, in the range of 0.55 mm or more and 1.35 mm or less, the size of the depth d and the length of the short axis of the flat conductor 11 obtained by rolling so as to satisfy the above relationship. It adjusts suitably according to the magnitude | size of b. For example, when the depth d of the grooves 132a and 132b is 3.50 mm, the width W of the grooves 132a and 132b is 1.00 mm or more according to the size of the length b of the short axis of the flat conductor 11. Adjust within the range of 1.25 mm or less. At this time, in particular, the width W of the grooves 132a and 132b preferably satisfies the relationship of W = d + 0.45 in relation to the length d of the short axis of the flat conductor 11. The size of the width W is the maximum value when the size of the grooves 132a and 132b is measured along the direction orthogonal to the depth d of the grooves 132a and 132b. The width W of the groove 132a included in the rolling roll 131a and the width W of the groove 132b included in the rolling roll 131b are preferably the same.

  Further, the grooves 132a and 132b have a concave shape that is recessed from the surface 134 of the rolling rolls 131a and 131b in the direction of the shafts 133a and 133b. Examples of the concave shape include a shape gradually reduced in diameter from the surface 134 of the rolling rolls 131a and 131b along the shafts 133a and 133b, a U shape, and a tapered shape.

  In the enameled wire manufacturing method according to the present embodiment, the wire 1 is rolled using the rolling rolls 131a and 131b including the grooves 132a and 132b having the specific depth d and width W described above, particularly in the rolling process. Thus, in one rolling process, the stress applied to the wire 1 can be reduced and the workability of the wire 1 can be increased so as not to be broken at the central portion of the long axis of the wire 1. As a result, in the enameled wire manufacturing method according to the present embodiment, a rectangular conductor having a large aspect ratio (that is, the ratio “a / b” between the major axis length a and the minor axis length b is 10 or more, Since the number of rolling operations for forming a flat conductor having a flat cross section with a short axis length b of 0.80 mm or less can be reduced, a flat square having a flat cross section with a large aspect ratio. It is possible to improve production efficiency when manufacturing an enameled wire including a conductor and the flat rectangular conductor.

(Annealing process)
In the annealing step, when the wire rod 1 rolled using the rolling rolls 131a and 131b shown in FIG. 3 is further rolled, the wire rod 1 is annealed by an annealing apparatus as a pre-process of the next rolling step. There is no particular limitation on the method of annealing the wire 1, for example, there is a method of transporting the wire 1 into the inside of the annealing furnace. In the annealing step, the wire 1 is annealed by such a method, so that the processing strain generated in the wire 1 by rolling can be reduced.

  In addition, after manufacturing the rectangular conductor 11 having the above-described rectangular shape shown in FIG. 1 in the rolling process, the rectangular conductor 11 in an unannealed state is conveyed to the coating process without going through the annealing process.

(Painting process)
Then, regarding the manufacturing method of the enameled wire 10, in the coating process, an insulating paint for forming the insulating film 12 to be coated on the outer periphery of the flat conductor 11 formed in the rolling process is applied.

  In the manufacturing method of the enameled wire 10 according to the present embodiment, it is preferable to use a coating die capable of adjusting the coating amount of the insulating coating coated around the flat conductor 11 in the coating process. As such a coating die, for example, there is one having a protrusion or the like at a predetermined position facing the surface of the flat conductor 11. By applying the coating die having such protrusions, the insulating paint to be applied around the flat conductor 11 is excessively applied, and the corner portion of the flat conductor 11 is applied by the surface tension of the insulating paint. It is possible to prevent the coating amount of the insulating paint from decreasing. Therefore, it is possible to prevent the insulating film 12 formed around the flat conductor 11 from having a nonuniform thickness.

  As the insulating paint to be applied to the outer periphery of the flat conductor 11, a resin component that constitutes the insulating film 12 is dissolved in an organic solvent. For example, an insulating paint in which a resin made of polyimide, polyamideimide, or the like is dissolved in polar solvents such as dimethylformamide (DMF), dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP) is used. be able to. Further, for example, an insulating paint in which a resin made of formal, polyurethane, polyester, polyesterimide, or the like is dissolved in cresol or xylol can be used.

(Heating process)
Subsequently, in the heating process, the rectangular conductor 11 coated with the insulating paint in the painting process is introduced into a heating device and heated. The rectangular conductor 11 coated with the insulating paint is heated to a specific temperature by a heating device, whereby the insulating paint applied to the outer periphery of the flat conductor 11 is cured and the flat conductor 11 is softened. In the heating step, the insulating film 12 is formed on the outer periphery of the flat conductor 11 by heating in this way.

  In the enameled wire manufacturing method according to the present embodiment, the insulating film 12 having a desired thickness (for example, a thickness of 20 μm or more and 100 μm or less) is formed on the outer periphery of the rectangular conductor 11 by repeating the coating process and the heating process a plurality of times. can get.

  By passing through the above steps, a flat wire having an insulating film 12 formed on the outer periphery of the flat conductor 11 is obtained, and the enameled wire 10 described above can be manufactured by winding the flat wire with a winder. it can.

  In addition, in the manufacturing method of the enameled wire 10 mentioned above, the rectangular conductor at the time of forming the insulating film 12 by performing the insulating film formation process comprised by a coating process and a heating process with a separate manufacturing line from a rolling process. 11 is less likely to be twisted. Therefore, in the manufacturing method in which such an insulating film forming process is performed on a separate production line from the rolling process, the thickness of the insulating film 12 is easily made uniform, so that the above-described elongation rate, tensile strength, 0.2% proof stress, etc. The enameled wire 10 having these characteristics can be manufactured more stably.

  Moreover, in the manufacturing method of the flat conductor 11 or the enameled wire 10 described above, a flat conductor having a rectangular cross section with a large aspect ratio is obtained by rolling a wire made of a metal wire having a circular cross section with a rolling device. Although the example which forms 11 was shown, it is not limited to this. For example, in the manufacturing method of the flat conductor 11 or the enameled wire 10 according to the present embodiment, a metal wire having a circular cross section is supplied to an extruder such as a conform extruder, and the supplied metal wire is supplied by the extruder. You may have the extrusion process of forming the wire for rolling in a rolling process in the pre-process of a rolling process by extrusion-molding a cross section to a flat shape.

  In the extrusion molding process, for example, a metal wire having a diameter of about 8 mm to 12 mm and having a circular cross section is extruded by a extruder into a wire having a flat cross section. This extruded wire becomes a wire for rolling. When the metal wire is made of pure copper such as tough pitch copper or oxygen-free copper, the wire in the state of an annealed copper wire is extruded from the extruder. In the rolling step, the wire having a rectangular cross section is rolled using the rolling roll shown in FIG. 3, whereby the ratio “a / b” between the length a of the major axis and the length b of the minor axis. ”Is 10 or more (for example, 10 or more and 25 or less), and the rectangular conductor 11 having a cross-sectional shape with a short axis length b of 0.8 mm or less (for example, 0.40 mm or more and 0.80 mm or less) is manufactured. .

  In the manufacturing method of the enameled wire 10 according to the present embodiment, by having the extrusion molding process described above, it is possible to reduce the number of rolling processes and the number of annealing processes accompanying the reduction in the number of rolling processes. That is, in the method for manufacturing the flat conductor 11 or the enameled wire 10 according to the present embodiment, further improvement in production efficiency can be expected by combining the extrusion process and the rolling process described above.

  Moreover, in the manufacturing method of the enameled wire 10 according to the present embodiment, when manufacturing a rectangular conductor having an aspect ratio of a cross section of 10: 1 or more and a short axis length of 0.80 mm or less using rolling. The rectangular conductor 11 may be manufactured by repeating the rolling process and the annealing process a plurality of times without using the rolling roll shown in FIG.

  In the case of manufacturing the rectangular conductor 11 having a rectangular cross section with a large aspect ratio by repeating the rolling process and the annealing process without using the rolling roll shown in FIG. 3 a plurality of times, the rolling roll shown in FIG. Similar to the case of using, it is possible to obtain the enameled wire 10 having the above-described characteristics. However, when the rolling roll shown in FIG. 3 is not used, the number of processes is increased as compared with the case where the rolling roll shown in FIG. 3 is used. Therefore, from the viewpoint of improving production efficiency, an enameled wire manufacturing method including a rolling process using a rolling roll shown in FIG. 3 is preferable.

[Effects of this embodiment]
According to the present embodiment, a rectangular crossing having a ratio “a / b” of the major axis length a to the minor axis length b of 10 or more and a minor axis length b of 0.80 mm or less. An enameled wire having a flat conductor 11 having a surface and an insulating film 12 coated on the outer periphery of the flat conductor 11, having an elongation of 40% or more, a tensile strength of 280 MPa or more, and a 0.2% proof stress of 65 MPa or more. By doing so, in the enameled wire having a large aspect ratio, it is possible to make the insulating film 12 hardly crack due to edgewise bending during coil forming.

  Further, according to the present embodiment, the ratio “a / b” between the major axis length “a” and the minor axis length “b” is 10 or more by rolling the wire using a rolling roll, and the minor axis length is increased. A rolling step of forming a rectangular conductor having a rectangular cross section with a length b of 0.80 mm or less, and an insulating film forming step of forming an insulating film coated on the outer periphery of the rectangular conductor, the rolling In the step, a depth d having a size of 0.20 times or more and less than 0.50 times the length a of the long axis of the flat rectangular conductor obtained by rolling on the part where the rolling roll rolls the wire, and the depth In relation to d, a wire having a width W satisfying 2 ≦ d / W ≦ 6 is provided, and the wire is rolled by passing through a rolling roll so that the wire is in contact with the inner surface of the groove. Thereby, in the manufacturing method of the enameled wire according to the present embodiment, when rolling with a rolling roll, the stress applied to the wire is reduced so that the wire does not break at the center portion of the long axis, and The degree of processing of the wire can be increased. As a result, in the enameled wire manufacturing method according to the present embodiment, the number of rolling and annealing steps can be reduced. Therefore, the above-described rectangular conductor 11 having a rectangular cross section with a large aspect ratio and the rectangular The enameled wire 10 including the conductor 11 can be efficiently manufactured.

  That is, according to the present embodiment, the flat conductor 11 having an aspect ratio of 10: 1 or more and a short axis length of 0.80 mm or less is provided, and the insulating film 12 against edgewise bending during coil forming. It is possible to provide an enameled wire 10 that is less prone to cracking and has excellent productivity and a method for manufacturing the same.

  Note that the enameled wire 10 according to the present embodiment is a drive motor used in, for example, EV (Electric Vehicle) and HEV (Hybrid Electric Vehicle), a DC boost coil used in solar power generation, or noise countermeasures for electrical equipment. It is suitable for the reactor coil used for etc.

  In Sample 1 shown in Table 1, a wire made of tough pitch copper (diameter: 12 mm) having a circular cross section is extruded into a flat rectangular shape using an extruder, and then a rolling roll shown in FIG. The length of the major axis a is 14 mm, the length of the minor axis b is 0.70 mm, and the curvature of the corner portion is rolled using a groove depth d: 3.50 mm and a groove width W: 1.15 mm. A rectangular conductor having a rectangular cross section with a radius of 0.30 mm was produced. Next, the insulating film made of polyimide is coated on the outer periphery of the rectangular conductor with an insulating paint in which an additive for improving adhesion is added and heated twice to repeat the first insulating film. Forming and applying a coating process for coating the outer periphery of the first insulating film with an insulating paint containing a resin of an insulating wire made of polyamideimide and a heating process for heating a flat conductor containing the coated insulating paint. Then, an enameled wire having an insulating film (first insulating film / second insulating film) having a thickness of 40 μm was manufactured by winding the film with a winder.

  In the sample 2 shown in Table 1, a wire rod made of tough pitch copper (diameter: 12 mm) having a circular cross section is used as a rolling roll (groove depth d: 1.50 mm or less, groove width W: 2.80 mm or less). Rolling is performed a plurality of times to produce a rectangular conductor having a rectangular shape in cross section with a major axis length a of 14 mm, minor axis length b of 0.70 mm, and a corner radius of curvature of 0.30 mm. did. Sample 2 was annealed in an annealing furnace when rolling a plurality of times. Next, the insulating film made of polyimide is coated on the outer periphery of the rectangular conductor with an insulating paint in which an additive for improving adhesion is added and heated twice to repeat the first insulating film. Forming and applying an insulating paint containing an insulating resin made of polyamideimide on the outer periphery of the first insulating film and a heating process for heating the flat conductor containing the coated insulating paint. The enameled wire provided with the insulating film (first insulating film / second insulating film) having a thickness of 43 μm was manufactured by forming the insulating film and winding the film with a winder.

  In Table 1 below, the characteristics of the enamel wires of Samples 1 and 2 were evaluated. Table 1 shows the results of evaluating the elongation rate, tensile strength, 0.2% proof stress, edgewise bending, and productivity as the properties of the enameled wire.

(Elongation rate, tensile strength, 0.2% proof stress)
In Table 1, the elongation rate and tensile strength of the enameled wire were measured by performing a tensile test according to a method based on JIS C3216-3 with an insulating film around a rectangular conductor. Further, the 0.2% proof stress of the enamel wire is obtained by drawing a tangent to the obtained stress-strain curve from the origin in the stress-strain curve obtained when measuring the above-described elongation rate and tensile strength, When a straight line parallel to the tangent line is drawn from a position where the strain is 0.2%, a point (intersection) where the stress-strain curve intersects the straight line is obtained, and the stress at this intersection point is measured as 0.2% proof stress. did.

(Edgewise bending)
In Table 1, the edgewise bending of the enameled wire is JIS C3216-3 JA. In the state of the enameled wire having an insulating film around the rectangular conductor. Tested by the method according to 5.1.2 a). In this test, the surface of the mandrel having a diameter of 16 mm is in contact with the surface of the insulating film located in the long axis direction of the enamel wire, and the enamel wire is bent 180 degrees edgewise. It was evaluated whether or not a crack occurred in the insulating film.

(productivity)
In Table 1, productivity was evaluated by the number of rolling operations when producing a rectangular conductor in the rolling process.

  As shown in Table 1, in the enamel wires of Samples 1 and 2, the ratio “a / b” between the major axis length a and the minor axis length b is 10 or more, and the minor axis length b is 0. In the state having an insulating film coated on the outer periphery of a rectangular conductor having a rectangular cross section of 80 mm or less, and having an insulating film on the outer periphery of the rectangular conductor, the elongation is 40% or more, the tensile strength is 280 MPa or less, The 0.2% proof stress is 65 MPa or more. By using such an enameled wire, an insulating film coated on the outer periphery of a rectangular conductor having a rectangular cross section with an aspect ratio of 10: 1 or more and a short axis length of 0.80 mm or less is an edge. It can be seen that cracks are less likely to occur when bent to width. In the enameled wire of Samples 1 and 2, when performing the edgewise bending described above, the portion to be bent (the portion to be bent by 180 degrees) becomes a shape that fluctuates in the direction of the short axis without using a jig or the like. It was possible to bend without

  Moreover, as shown in Table 1, in the enameled wire manufacturing method (sample 1 manufacturing method) including the rolling process using the rolling roll shown in FIG. 3, the enamel including the rolling process not using the rolling roll shown in FIG. It can be seen that the productivity is higher (that is, the production efficiency is better) than the method for producing the wire (the method for producing Sample 2).

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible within the range which does not deviate from the main point of invention.

  The embodiments described above do not limit the invention according to the claims. In addition, it should be noted that not all combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention.

10 Enamelled wire 11 Flat rectangular conductor 12 Insulation film

Claims (4)

A rectangular conductor having a rectangular cross section in which the ratio “a / b” of the length a of the major axis to the length b of the minor axis is 10 or more and the length b of the minor axis is 0.80 mm or less; ,
An insulating film coated on the outer periphery of the rectangular conductor,
An enameled wire having an elongation of 40% or more, a tensile strength of 280 MPa or less, and a 0.2% proof stress of 65 MPa or more. By rolling the wire using a pair of rolling rolls, the ratio “a / b” between the major axis length a and the minor axis length b is 10 or more, and the minor axis length b is 0. Rolling process for forming a rectangular conductor having a rectangular cross section of 80 mm or less;
Including an insulating film forming step of forming an insulating film covering the outer periphery of the rectangular conductor,
In the rolling step, a depth of 0.20 times or more and less than 0.50 times the length a of the long axis of the flat conductor obtained by rolling on the portion of the rolling roll where the wire is rolled. In relation to the depth d and the depth d, a groove having a width W satisfying 2 ≦ d / W ≦ 6 is provided, and the wire rod passes through the rolling roll so as to contact the inner surface of the groove. A method for producing enameled wire, in which a wire is rolled.   The method for producing an enameled wire according to claim 2, wherein the wire is a metal wire having a circular cross section and formed into a flat cross section having a minor axis length of greater than 0.80 mm by extrusion molding. .   3. The enameled wire according to claim 2, wherein the insulating film forming step includes a painting step of painting an insulating paint around the rectangular conductor using a coating die having a protrusion on an inner surface of an opening through which the rectangular conductor is inserted. Manufacturing method.

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