JP2022023932A - Enamel wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an enamel wire where an insulation film coated on an outer periphery of a flat-square conductor having a flat-squared cross section having an aspect ratio of 10:1 or more, and a length of a minor axis of 0.80 mm or less is hard to generate cracks against edge-wise bending, and a production method of the enamel wire.

SOLUTION: The enamel wire of the present invention includes: a flat-square conductor having a flat-squared cross section having a ratio (a/b) of a length (a) of a major axis to a length (b) of a minor axis of 10 or more, and the length (b) of the minor axis of 0.80 mm or less; and an insulation film coated on an outer periphery of the flat square conductor, where the elongation is 40% or more, the tensile strength is 280 MPa or less, the 0.2% bearing force is 65 MPa or more.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

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

The conventional enamel wire includes, for example, an enamel wire having an insulating film for covering the flat conductor on the outer periphery of the flat conductor having a flat cross section.

In Patent Document 1, the ratio a / b of the length a of the major axis and the length b of the minor axis, which are made of tough pitch copper or oxygen-free copper and have a rectangular cross section, is 15 or more, and the length of the minor axis is 15. b is 0.3 mm to 1.2 mm, the corners formed at the four corners of the rectangular cross section are chamfered with a radius of curvature of 0.05 mm to 0.60 mm, and the arithmetic average roughness Ra of the surface of the corners is 0. It is 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-angle insulated lead wire material for a coil is disclosed. Further, in Patent Document 1, when the above-mentioned flat-angle insulated conductor material for a coil is manufactured, a slit having a rectangular cross section is formed by slitting instead of the conventional method of rolling from a round wire to manufacture a flat-shaped conductor. It is said that it is obtained by a manufacturing method in which a strip is produced and then drawn to form a corner portion having a rectangular cross section.

Further, in Patent Document 1, by applying the above-mentioned flat-angle insulated conductor material for a coil and its manufacturing method, the radius of curvature of the corner portion of the rectangular cross section is accurately formed, and the flat-angled conductor itself is less likely to be bent or warped. It is said that an enamel wire having a stable resin coating can be obtained.

Japanese Unexamined Patent Publication No. 2012-195212

Aspect ratio consisting of the ratio of the length of the major axis to the length of the minor axis when the coil is formed by bending the enamel wire in the width direction (direction of the major axis) of the flat conductor (that is, edgewise bending). An enamel wire having a flat conductor having a flat cross section having a ratio of 10: 1 or more and a length of a minor axis of 0.80 mm or less is prone to cracks 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 an object thereof has a flat cross section having an aspect ratio of 10: 1 or more and a minor axis length of 0.80 mm or less. The insulating coating on the outer circumference of the flat conductor provides an enamel wire that is less prone to cracking against edgewise bending.

One aspect of the present invention provides the following enamel wire to achieve the above object.

[1] It has a flat 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. Elongation when a tensile test is performed by a method conforming to JIS C3216-3 with a flat conductor and an insulating film coated on the outer periphery of the flat conductor and having the insulating film around the flat conductor. An enamel wire having a ratio of 40% or more, a tensile strength of 280 MPa or less, and a 0.2% proof stress of 65 MPa or more.

According to the present invention, the insulating film coated on the outer circumference of a flat conductor having a flat cross section having an aspect ratio of 10: 1 or more and a minor axis length of 0.80 mm or less is resistant to edgewise bending. It is possible to provide an enamel wire that is less likely to crack.

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 at the time of manufacturing the enamel wire which concerns on one Embodiment of this invention. It is a schematic block diagram which shows the rolling roll used when the flat conductor is manufactured by rolling in the manufacturing method of the enamel wire which concerns on one Embodiment of this invention.

<One Embodiment of the present invention>
Hereinafter, the enamel wire according to the embodiment of the present invention and the method for producing the enamel wire will be described with reference to the drawings.

[Enamel wire]
FIG. 1 is a schematic cross-sectional view showing a configuration example of the enamel wire 10 according to the present embodiment.

As shown in FIG. 1, in the enamel wire 10 according to the present embodiment, 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 is It is provided with at least a flat conductor 11 having a flat cross section of 0.80 mm or less, and an insulating film 12 coated on the outer periphery of the flat conductor 11 for insulating the flat conductor 11. In the enamel wire 10 according to the present embodiment, the flat conductor 11 has, for example, a ratio "a / b" between the length a of the major axis and the length b of the minor axis of 10 or more and 25 or less, and is of the minor axis. Those having a flat cross section having a length b of 0.40 mm or more and 0.80 mm or less are targeted.

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

The enamel wire 10 preferably has an elongation rate of 40% or more in a state where the insulating film 12 is provided on the outer periphery of the flat conductor 11. As a result, the enamel wire 10 has a ratio "a / b" of 10 or more between the length a of the major axis of the flat conductor 11 and the length b of the minor axis, and the length b of the minor axis is 0.80 mm or less. In a certain case, when the enamel wire 10 is bent edgewise during coil molding (hereinafter, also referred to as "edgewise bending"), the insulating film 12 (particularly, curved by edgewise bending) of the bent portion is curved. It is possible to prevent cracks from occurring in the insulating film 12) near the top of the portion.

Further, the enamel 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. Further, the 0.2% proof stress in the state where the insulating film 12 is provided around the flat conductor 11 is preferably 65 MPa or more, more preferably 70 MPa or more and 95 MPa or less. Since the enamel wire 10 has such tensile strength and 0.2% proof stress, the ratio “a / b” of the length a of the major axis to the length b of the minor axis of the flat conductor 11 is 10 or more. When the length b of the minor axis is 0.80 mm or less, the insulating film 12 of the portion where the bending is applied (particularly, the portion curved by the edgewise bending) with respect to the edgewise bending at the time of coil forming. It is possible to prevent cracks from occurring in the insulating film 12) near the top.

Further, in the enamel wire 10 according to the present embodiment, the portion curved by the edgewise bending when the coil is formed by the edgewise bending due to having the above-mentioned specific elongation, tensile strength, and 0.2% proof stress. Can be bent without causing the shape to fluctuate in the direction of the minor axis (for example, the enamel wire 10 is bent).

The elongation and tensile strength of the enamel wire 10 can be determined by a method conforming to JIS C3216-3. Further, the 0.2% proof stress of the enamel wire 10 draws a tangent line to the obtained stress-strain curve from the origin in the stress-strain curve obtained when measuring the above elongation and tensile strength, and then draws a tangent line to the obtained stress-strain curve. , When a straight line parallel to the tangent line is drawn from the position where the strain is 0.2%, the point (intersection point) where the stress-strain curve and the straight line intersect is obtained, and the stress at this intersection is used as the 0.2% proof stress. Can be calculated.

(Flat conductor)
The flat conductor 11 has a ratio "a / b" of the length a of the major axis to the length b of the minor axis of 10 or more, and the length b of the minor axis is 0.80 mm or less. For example, the flat conductor 11 has a “a / b” of 10 or more and 25 or less, and a minor axis length b of 0.40 mm or more and 0.80 mm or less. Further, the length a of the long axis of the flat conductor 11 is preferably 6 mm or more and 16 mm or less. Further, the flat conductor 11 has a cross section 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 or more and 0.60 mm or less). Since the flat conductor 11 has such a shape, it can be made into a coil having a reduced thickness in the minor axis direction when the enamel wire 10 is formed into a coil. Further, since the flat conductor 11 has such a shape, the surface area of the flat conductor 11 can be increased without reducing the area of the cross section of the flat conductor 11 in the enamel wire 10. Therefore, in the enamel wire 10 provided with the flat conductor 11, the resistance value increase rate in the high frequency region (for example, 100 kHz) can be reduced.

The flat conductor 11 is made of a metal having high conductivity, for example, low oxygen copper or oxygen-free copper, a copper alloy having conductivity equivalent to that of pure copper thereof, or a metal such as aluminum.

(Insulation film)
The insulating film 12 is covered with an insulating film made of an insulating resin selected from, for example, polyamide-imide, polyimide, and polyesterimide on the outer periphery of the flat conductor 11. In particular, the insulating film 12 is preferably made of a resin made of polyamide-imide or polyimide from the viewpoint of increasing heat resistance. The thickness of the insulating film 12 is, for example, 20 μm or more and 100 μm or less. 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 on the outer periphery of the flat conductor 11 as one layer. For example, the first insulation is coated on the outer periphery of the flat conductor 11 to improve the adhesion with the flat conductor 11. The two-layer insulating film 12 may have a film and a second insulating film made of the above-mentioned resin coated on the outer periphery of the first insulating film. By covering the enamel wire 10 with the first insulating film that improves the adhesion so as to be in contact with the flat conductor 11, the insulating film 12 is peeled from the flat conductor 11 against edgewise bending during coil forming. It can be made difficult to break, and it also becomes difficult to break. The first insulating film that improves adhesion is melamine in an insulating resin selected from, for example, polyamideimide, polyimide, and polyesterimide from the viewpoint of maintaining high insulation and maintaining high adhesion. It is composed of those to which an additive that improves adhesion such as class is added.

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

[Manufacturing method of enamel wire]
Next, a method for producing an enamel wire according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG. 2 is an explanatory diagram showing an example of a flow when manufacturing an enamel wire according to an embodiment of the present invention, and FIG. 3 is a flat conductor in a method for manufacturing an enamel wire according to an embodiment of the present invention. It is a schematic block diagram which shows the rolling roll used when manufacturing by rolling.

In the method for manufacturing an enamel wire according to the present embodiment, for example, the flat conductor 11 and the enamel 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 enamel wire according to the present embodiment, a wire rod made of a metal wire rod having a predetermined outer shape is sent from a feeder to a rolling apparatus, and the wire rod is subjected to the above-mentioned flat cross section by the rolling apparatus. It has a rolling step of rolling into a flat conductor 11 having the above, a painting step of painting an insulating paint on 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. .. In the method for manufacturing an enamel wire according to the present embodiment, the flat wire rod obtained by performing the above-mentioned rolling step, painting step, and heating step is wound by a winder to form the flat conductor 11 shown in FIG. An enamel wire 10 having an insulating film 12 on the outer periphery can be obtained.

In addition, each of these steps may be performed on a part or all of the steps on the same production line. When the rolling step is performed a plurality of times, it is preferable to have an annealing step of annealing the flat conductor obtained by rolling between the rolling step of the previous step and the next step.

In the following, each step described above will be described in detail.

(Rolling process)
In the rolling process for forming the flat conductor 11, a wire rod made of a metal wire rod is rolled by a rolling apparatus. 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 that of pure copper thereof, or a metal such as aluminum. When the cross section of the wire is circular, the diameter of the wire is about 8 mm or more and 12 mm or less. When the metal wire is made of low-oxygen copper, oxygen-free copper, or a copper alloy having the same conductivity as these pure coppers, the metal wire should be annealed copper wire from the viewpoint of ease of rolling of the metal wire. Is preferable.

In this rolling step, as shown in FIG. 3, the wire rod 1 is rolled one or more times using the pair of rolling rolls 131a and 131b of the rolling apparatus to obtain the length a of the major axis and the length b of the minor axis. A flat conductor having a flat cross section having a ratio "a / b" of 10 or more and a length b of a short axis of 0.80 mm or less is manufactured. The length a of the long axis of the flat conductor is 6 mm or more and 16 mm or less. For a flat conductor, for example, 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 25 or less, and the length b of the minor axis is 0.40 mm or more and 0.80 mm or less. It has a flat cross section.

The rolling rolls 131a and 131b used in the rolling step are provided with grooves 132a and 132b having a specific depth d in the portion where the wire rod 1 is rolled. Then, as shown in FIG. 3, the wire rod 1 passes through the inside of the rolling roll so that the wire rod 1 contacts a part or all of the inner surfaces of the grooves 132a and 132b of the pair of rolling rolls 131a and 131b facing each other. At this time, the rolling rolls 131a and 131b rotate in the same direction with the shafts 133a and 133b as the central axis to roll the wire rod 1. By performing such a rolling step once or more, preferably once or more and three times or less, the flat conductor 11 having the above-mentioned flat 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 length a of the long axis of the flat conductor 11 obtained by rolling the wire rod 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 length a of the long axis of the flat conductor 11 obtained by rolling. The size of the depth d is the distance from the bottom of the grooves 132a and 132b to the surface 134 of the rolling rolls 131a and 131b. Further, it is preferable that the depth d of the groove 132a of the rolling roll 131a and the depth d of the groove 132b of the rolling roll 131b are the same size.

In addition to this, it is preferable that the rolling rolls 131a and 131b have a size in which the width W of the grooves 132a and 132b of the portion where the wire rod 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, the size of the depth d or the length of the minor axis of the flat conductor 11 obtained by rolling so as to satisfy the above relationship in the range of 0.55 mm or more and 1.35 mm or less. Adjust appropriately according to the 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 depending on the size of the length b of the minor axis of the flat conductor 11. Adjust within a range of 1.25 mm or less. At this time, it is more preferable that the width W of the grooves 132a and 132b satisfies the relationship of W = d + 0.45 in relation to the length d of the minor axis of the flat conductor 11. The size of the width W is a value at which the size of the grooves 132a and 132b becomes maximum 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. Further, it is preferable that the width W of the groove 132a of the rolling roll 131a and the width W of the groove 132b of the rolling roll 131b are the same size.

Further, the grooves 132a and 132b have a concave shape 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 in which the diameter is gradually reduced 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 method for producing an enamel wire according to the present embodiment, particularly in the rolling step, the wire rod 1 is rolled using the rolling rolls 131a and 131b provided with the grooves 132a and 132b having the above-mentioned specific depth d and width W. Thereby, in one rolling process, the stress applied to the wire rod 1 can be reduced and the degree of processing of the wire rod 1 can be increased so as not to break at the central portion of the long axis of the wire rod 1. As a result, in the method for manufacturing an enamel wire according to the present embodiment, a flat conductor having a large aspect ratio (that is, the ratio "a / b" between the length a of the major axis and the length b of the minor axis is 10 or more. Since the number of rolling times for forming a flat conductor having a flat cross section having a length b of the minor axis of 0.80 mm or less can be reduced, a flat angle having a flat cross section having a large aspect ratio can be reduced. It is possible to improve the production efficiency when manufacturing a conductor and an enamel wire including the flat conductor.

(Annealing process)
In the annealing step, when the wire rod 1 rolled by using the rolling rolls 131a and 131b shown in FIG. 3 is further rolled, the wire rod 1 is annealed by an annealing device as a pre-step of the rolling step of the next step. The method of annealing the wire 1 is not particularly limited, and for example, there is a method of transporting the wire 1 inside the annealing furnace. In the annealing step, by annealing the wire rod 1 by such a method, it is possible to reduce the processing strain generated in the wire rod 1 by the rolling process.

In the rolling step, after the flat conductor 11 having the above-mentioned flat shape shown in FIG. 1 is manufactured, the flat conductor 11 in an unannealed state is conveyed to the painting step without going through the annealing step.

(Painting process)
Subsequently, regarding the method for manufacturing the enamel wire 10, in the painting step, an insulating paint for forming the insulating film 12 to be covered on the outer periphery of the flat conductor 11 formed in the rolling step is coated.

In the method for manufacturing the enamel wire 10 according to the present embodiment, it is preferable to use a coating die capable of adjusting the coating amount of the insulating paint 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 a coating die having such protrusions, the insulating paint to be painted around the flat conductor 11 is excessively painted, and the surface tension of the insulating paint is applied to the corners of the flat conductor 11. It is possible to prevent the amount of the insulating paint from being reduced. Therefore, it is possible to prevent the insulating film 12 formed around the flat conductor 11 from having a non-uniform thickness.

As the insulating paint coated on the outer periphery of the flat conductor 11, a resin component constituting the insulating film 12 dissolved in an organic solvent can be used. For example, an insulating coating material obtained by dissolving a resin made of polyimide, polyamide-imide, or the like in a polar solvent such as dimethylformamide (DMF), dimethylacetamide (DMAC), dimethylsulfoxide (DMSO), or 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, xylene, or the like can also be used.

(Heating process)
Subsequently, in the heating step, the flat conductor 11 coated with the insulating paint by the painting step is introduced into the heating device and heated. When the flat conductor 11 coated with the insulating paint is heated to a specific temperature by a heating device, the insulating paint painted on 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 method for manufacturing an enamel wire according to the present embodiment, the coating step and the heating step are repeated a plurality of times to form an insulating film 12 having a desired thickness (for example, a thickness of 20 μm or more and 100 μm or less) on the outer periphery of the flat conductor 11. can get.

By going through each of the above steps, a flat wire having an insulating film 12 formed on the outer periphery of the flat conductor 11 can be obtained, and the flat wire can be wound by a winder to manufacture the above-mentioned enamel wire 10. can.

In the method for manufacturing the enamel wire 10 described above, the flat conductor for forming the insulating film 12 is formed by performing the insulating film forming step consisting of the painting step and the heating step on a manufacturing line different from the rolling step. Twisting is unlikely to occur in 11. Therefore, in a manufacturing method in which such an insulating film forming process is performed on a production line different from the rolling process, the thickness of the insulating film 12 can be easily made uniform, so that the above-mentioned elongation rate, tensile strength, 0.2% proof stress, etc. The enamel wire 10 having various characteristics of the above can be manufactured more stably.

Further, in the method for manufacturing the flat conductor 11 or the enamel wire 10 described above, a flat conductor having a flat cross section having a large aspect ratio is obtained by rolling a wire made of a metal wire having a circular cross section with a rolling apparatus. Although an example of forming 11 is shown, the present invention is not limited to this. For example, in the method for manufacturing a flat conductor 11 or an enamel 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. An extrusion molding step of forming a wire rod for rolling in the rolling step by extrusion molding into a flat cross section may be included in the pre-rolling step.

In the extrusion molding step, for example, a metal wire having a diameter of 8 mm or more and 12 mm or less and having a circular cross section is extruded by an extruder to have 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 annealed copper wire is extruded from the extruder. Then, in the rolling step, the wire rod having a flat cross section is rolled by using the rolling roll shown in FIG. 3, so that the ratio “a / b” of the length a of the major axis to the length b of the minor axis is obtained. Is 10 or more (for example, 10 or more and 25 or less), and the length b of the minor axis is 0.8 mm or less (for example, 0.40 mm or more and 0.80 mm or less). ..

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

Further, in the method for manufacturing the enamel wire 10 according to the present embodiment, when a flat conductor having a cross-sectional aspect ratio of 10: 1 or more and a minor axis length of 0.80 mm or less is manufactured by rolling. The flat conductor 11 may be manufactured by repeating the rolling step and the annealing step a plurality of times without using the rolling roll shown in FIG.

In the case of manufacturing a flat conductor 11 having a flat cross section having a large aspect ratio by repeating such a rolling step without using the rolling roll shown in FIG. 3 and an annealing step a plurality of times, the rolling roll shown in FIG. 3 is used. It is possible to obtain the enamel wire 10 having the above-mentioned characteristics as in the case of using it. However, when the rolling roll shown in FIG. 3 is not used, the number of steps is larger than that when the rolling roll shown in FIG. 3 is used. Therefore, from the viewpoint of improving production efficiency, a method for producing an enamel wire including a rolling step using a rolling roll shown in FIG. 3 is preferable.

[Effects of the present embodiment]
According to the present embodiment, 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 is 0.80 mm or less. An enamel wire comprising 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 ratio of 40% or more, a tensile strength of 280 MPa or more, and a 0.2% strength of 65 MPa or more. By doing so, it is possible to prevent cracks from being generated in the insulating film 12 due to edgewise bending during coil forming in the enamel wire having a large aspect ratio.

Further, according to the present embodiment, the ratio "a / b" between the length a of the major axis and the length b of the minor axis is 10 or more by rolling the wire rod using a rolling roll, and the length of the minor axis is long. The rolling includes a rolling step of forming a flat conductor having a flat cross section in which b is 0.80 mm or less, and an insulating film forming step of forming an insulating film coated on the outer periphery of the flat conductor. In the process, a depth d and a depth 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 in the portion where the rolling roll rolls the wire rod. In relation to d, a groove 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. As a result, in the method for manufacturing an enamel wire according to the present embodiment, when rolling with a rolling roll, the stress applied to the wire rod is reduced so that the wire rod does not break at the central portion of the long axis thereof, and the stress applied to the wire rod is reduced. The degree of processing of the wire can be increased. As a result, in the method for manufacturing an enamel wire according to the present embodiment, the number of rolling steps and annealing steps can be reduced. Therefore, the flat conductor 11 having a flat cross section having a large aspect ratio and the flat angle described above and the flat angle thereof. The enamel wire 10 provided with 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 length of a minor axis of 0.80 mm or less is provided, and the insulating film 12 is resistant to edgewise bending during coil forming. It is possible to provide an enamel wire 10 which is less likely to be cracked and has excellent productivity and a method for producing the same.

The enamel wire 10 according to the present embodiment is, for example, a drive motor used for an EV (Electric Vehicle), a HEV (Hybrid Electric Vehicle), a DC boost coil used for solar power generation, or a noise countermeasure for an electric device. It is suitable for reactor coils used for such purposes.

In the sample 1 shown in Table 1, a wire rod made of tough pitch copper (diameter: 12 mm) having a circular cross section is extruded into a flat cross section using an extruder, and then a rolling roll shown in FIG. 3 (rolling roll). By rolling using the groove depth d: 3.50 mm, groove width W: 1.15 mm), the length a of the major axis is 14 mm, the length b of the minor axis is 0.70 mm, and the curvature of the corners. A flat conductor having a flat cross section having a radius of 0.30 mm was produced. Next, the outer periphery of this flat conductor is coated with an insulating paint containing an additive for improving adhesion to an insulating resin made of polyimide, and heated twice to form the first insulating film. By repeating the painting process of forming and coating the outer periphery of the first insulating film with an insulating paint containing a resin of an insulating wire made of polyamideimide and the heating step of heating a flat conductor containing the painted insulating paint, the second step is performed. By forming the insulating film of the above and winding it with a winder, an enamel wire having an insulating film having a thickness of 40 μm (first insulating film / second insulating film) was manufactured.

In Sample 2 shown in Table 1, a wire rod made of tough pitch copper (diameter: 12 mm) having a circular cross section is rolled into a rolling roll (groove depth d: 1.50 mm or less, groove width W: 2.80 mm or less). Rolling is performed multiple times using did. In Sample 2, annealing was performed in an annealing furnace when rolling was performed a plurality of times. Next, the outer periphery of this flat conductor is coated with an insulating paint containing an additive for improving adhesion to an insulating resin made of polyimide, and heated twice to form the first insulating film. The second step is to repeat the steps of forming and coating the outer periphery of the first insulating film with an insulating paint containing an insulating resin made of polyamideimide, and the heating step of heating the flat conductor containing the painted insulating paint. By forming the insulating film of the above and winding it with a winder, an enamel wire having an insulating film having a thickness of 43 μm (first insulating film / second insulating film) was manufactured.

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 the results of evaluating the productivity as the characteristics of the enamel wire.

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

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

(Productivity)
In Table 1, productivity was evaluated by the number of rolling times when a flat conductor was produced in the rolling step.

As shown in Table 1, in the enamel wires of Samples 1 and 2, 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 is 0. With an insulating film coated on the outer circumference of a flat conductor having a flat cross section of .80 mm or less and an insulating film on the outer circumference of the flat conductor, the elongation rate is 40% or more, and the tensile strength is 280 MPa or less. The 0.2% proof stress is 65 MPa or more. By using such an enamel wire, the insulating film coated on the outer periphery of the flat conductor having a flat cross section having an aspect ratio of 10: 1 or more and a length of the minor axis of 0.80 mm or less is an edge. It can be seen that cracks are unlikely to occur when bent wisely. In the enamel wires of Samples 1 and 2, when the above-mentioned edgewise bending is performed, the curved portion (the portion to be bent 180 degrees) has a shape that fluctuates in the direction of the minor axis without using a jig or the like. I was able to bend it without.

Further, as shown in Table 1, in the enamel wire manufacturing method (manufacturing method of sample 1) including the rolling step using the rolling roll shown in FIG. 3, the enamel including the rolling step not using the rolling roll shown in FIG. It can be seen that the productivity is superior (that is, the production efficiency is good) to the wire production method (sample 2 production method).

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be carried out within a range that does not deviate from the gist of the invention.

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

10 Enamel wire 11 Flat conductor 12 Insulation film

Claims (6)

A flat conductor having a flat 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. ,
With an insulating film coated on the outer periphery of the flat conductor,
When a tensile test is performed by a method conforming to JIS C3216-3 with the insulating film around the flat conductor, the elongation rate is 40% or more, the tensile strength is 280 MPa or less, and the 0.2% proof stress is 65 MPa or more. Is an enamel wire. The insulating film is composed of an insulating resin selected from polyamide-imide, polyimide, and polyesterimide (excluding the block copolymer polyimide resin having a siloxane bond in the molecular skeleton).
The enamel wire according to claim 1. The insulating film has a film composed of an insulating resin made of polyamide-imide.
The enamel wire according to claim 1 or 2. The insulating film has a first insulating film formed on the outer periphery of the conductor and a second insulating film formed on the outer periphery of the first insulating film.
The enamel wire according to any one of claims 1 to 3. An additive for improving the adhesion to the conductor is added to the first insulating film.
The enamel wire according to claim 4. With the insulating film around the flat conductor, the mandrel with a diameter of 16 mm was bent 180 degrees edgewise with the surface of the insulating film in contact with the surface of the mandrel using a method conforming to JIS C3216-3. Sometimes the insulating film does not crack,
The enamel wire according to any one of claims 1 to 5.

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