JP7301930B2 - enamelled wire - Google Patents

Description

TECHNICAL FIELD The present invention relates to an enameled wire used for coils for electrical equipment such as motors and transformers, and a method for manufacturing the enameled wire.

A conventional enameled wire includes, for example, an enameled wire having an insulating film for covering the rectangular conductor having a rectangular cross section on the outer circumference of the rectangular conductor.

In Patent Document 1, it is made of tough-pitch copper or oxygen-free copper, and has a rectangular cross-section with a long axis length a to a short axis length b ratio a/b of 15 or more, and a short axis length 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 curvature radius of 0.05 mm to 0.60 mm, and the arithmetic average roughness Ra of the surface of the corners 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 rectangular insulated conductor material for a coil is disclosed. Further, in Patent Document 1, when manufacturing the rectangular insulated conductor wire material for coils described above, instead of the conventional method of rolling a round wire to manufacture a rectangular conductor wire, slit processing is performed to obtain a slit having a rectangular cross section. It is said to be obtained by a manufacturing method in which a strip is prepared and then drawn to form corners of a rectangular cross section.

In Patent Document 1, by applying the rectangular insulated conductor material for coil and the manufacturing method thereof described above, the radius of curvature of the corners of the rectangular cross section is formed with high precision, and the rectangular conductor itself is less likely to bend or warp. An enameled wire having a stable resin coating is said to be obtained.

JP 2012-195212 A

When the coil is formed by bending the enameled wire in the width direction (long axis direction) of the rectangular conductor (that is, edgewise bending), the aspect ratio is the ratio of the length of the long axis to the length of the short axis. is 10:1 or more and the length of the short axis is 0.80 mm or less. .

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

One aspect of the present invention provides the following enameled wire in order to achieve the above object.

[1] It has 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. Elongation when a tensile test is performed by a method conforming to JIS C3216-3 in a state in which a rectangular conductor and an insulating film coated on the outer periphery of the rectangular conductor are provided, and the insulating film is provided around the rectangular conductor. An enameled wire having a modulus of 40% or more, a tensile strength of 280 MPa or less, and a 0.2% yield strength of 65 MPa or more.

According to the present invention, the 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 resistant to edgewise bending. It is possible to provide an enameled wire that is resistant to cracking.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic cross-sectional view which shows the structural example of the enameled wire which concerns on one Embodiment of this invention. FIG. 2 is an explanatory diagram showing an example of the flow when manufacturing an enameled wire according to one embodiment of the present invention; 1 is a schematic configuration diagram showing rolling rolls used when producing a rectangular conductor by rolling in a method for producing an enameled wire according to an embodiment of the present invention; FIG.

<One embodiment of the present invention>
An enameled wire and a method for manufacturing an enameled wire according to an embodiment of the present invention will be described below with reference to the drawings.

[Enameled wire]
FIG. 1 is a schematic cross-sectional view showing a structural example of an enameled wire 10 according to this embodiment.

In the enameled wire 10 according to the present embodiment, as shown in FIG. 1, 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 comprises at least a rectangular conductor 11 having a rectangular cross section of 0.80 mm or less, and an insulating coating 12 covering the outer periphery of the rectangular conductor 11 and insulating the rectangular conductor 11 . In addition, in the enameled wire 10 according to the present embodiment, the rectangular 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. The object is to have 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 length a of the major axis is the length between the two opposing short sides 111 and 112 of the rectangular conductor 11 , and the length b of the minor axis is the length of the two opposite sides 111 and 112 of the rectangular conductor 11 . is the length between two long sides 113, 114.

It is preferable that the enameled wire 10 has an elongation rate of 40% or more when the rectangular conductor 11 has the insulating coating 12 on its outer periphery. As a result, the enameled wire 10 has a ratio "a/b" between the long axis length a and the short axis length b of the rectangular conductor 11 of 10 or more, and the short axis length b is 0.80 mm or less. In some cases, when the enameled wire 10 is edgewise bent (hereinafter also referred to as “edgewise bending”) during coil forming, the insulating film 12 (particularly, the portion bent by the edgewise bending) to which the bending is applied is formed. It is possible to make cracks less likely to occur in the insulating coating 12) in the vicinity of 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 rectangular conductor 11 has the insulating coating 12 on its outer periphery. Furthermore, the 0.2% proof stress with the insulating film 12 around the flat 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 length a of the long axis and the length b of the short axis of the rectangular conductor 11 is 10 or more. , When the length b of the minor axis is 0.80 mm or less, the insulating coating 12 at the portion where bending is applied to the edgewise bending at the time of coil forming (especially, the portion curved by edgewise bending) It is possible to make cracks less likely to occur in the insulating coating 12) near the top.

Further, since the enameled wire 10 according to the present embodiment has the above-described specific elongation, tensile strength, and 0.2% proof stress, when the coil is formed by edgewise bending, the portion curved by edgewise bending can be bent without causing the wire to sway in the direction of the minor axis (for example, the enameled wire 10 is bent).

The elongation percentage and tensile strength of the enameled wire 10 can be obtained by a method conforming to JIS C3216-3. In addition, the 0.2% yield strength of the enameled wire 10 is obtained in the stress-strain curve obtained when measuring the elongation rate and tensile strength, and the obtained stress-strain curve is drawn from the origin. , when a straight line parallel to the tangent is drawn from the position where the strain is 0.2% - find the point (intersection) where the strain curve and the straight line intersect, and the stress at this intersection as 0.2% yield strength can be calculated.

(rectangular conductor)
The rectangular conductor 11 has a ratio "a/b" between the length a of the long axis and the length b of the short axis of 10 or more, and the length b of the short axis is 0.80 mm or less. For example, the rectangular conductor 11 should have a ratio of "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, the length a of the major axis of the rectangular conductor 11 is preferably 6 mm or more and 16 mm or less. Furthermore, the rectangular conductor 11 has a curved cross section with four corners having a specific curvature radius (for example, a curvature radius of 0.10 mm or more and 0.60 mm or less). By forming the rectangular conductor 11 in such a shape, it is possible to form a coil having a smaller thickness in the minor axis direction when the enameled wire 10 is formed into a coil. Further, the rectangular conductor 11 having such a shape can increase the surface area without reducing the cross-sectional area of the rectangular conductor 11 in the enameled wire 10 . Therefore, the enameled wire 10 including the rectangular conductor 11 can reduce the rate of increase in resistance value in a high frequency region (for example, 100 kHz).

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

(insulating film)
The insulating film 12 is formed by covering the outer circumference of the rectangular 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 made of a resin such as polyamide-imide or polyimide from the viewpoint of increasing heat resistance. Moreover, the insulating coating 12 has a thickness of, for example, 20 μm or more and 100 μm or less. The thickness of the insulating coating 12 can be appropriately adjusted according to changes in characteristics such as withstand voltage.

In FIG. 1 , the insulating film 12 is provided as a single layer on the outer periphery of the rectangular conductor 11 . A two-layer insulating coating 12 having a coating and a second insulating coating made of the resin described above and coated on the outer periphery of the first insulating coating may be used. By covering the flat conductor 11 with the first insulating film that improves adhesion, the insulating film 12 peels off from the flat conductor 11 when the enameled wire 10 is edgewise bent during coil forming. It can be made difficult to break, and it is also difficult to break. For the first insulation film that improves adhesion, from the viewpoint of maintaining high insulation and providing high adhesion, for example, melamine is added to an insulating resin selected from polyamideimide, polyimide, and polyesterimide. It is composed of a material to which an additive that improves adhesion such as a type is added.

Further, the enameled wire 10 may have the insulating coating 12 on the outer periphery of the rectangular conductor 11 and may further have other coatings having lubricating properties and fusion bonding properties on the outer periphery of the insulating coating 12 .

[Manufacturing method of enameled wire]
Next, an enameled wire manufacturing method according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 is an explanatory diagram showing an example of the flow of manufacturing an enameled wire according to an embodiment of the present invention, and FIG. is a schematic configuration diagram showing rolling rolls used when manufacturing by rolling.

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

More specifically, in the method for manufacturing an enameled wire according to the present embodiment, a wire rod made of a metal wire rod having a predetermined outer shape is fed from a feeder to a rolling device, and the wire rod is formed into the above-described rectangular cross section by the rolling device. a rolling step of rolling into a rectangular conductor 11 having a; a painting step of applying insulating paint to the outer circumference of the rectangular conductor 11 obtained by rolling; and a heating step of heating the rectangular conductor 11 coated with the insulating paint. . Then, in the method for manufacturing an enameled wire according to the present embodiment, the rectangular wire rod obtained by performing the rolling process, the coating process and the heating process described above is wound by a winding machine to form the rectangular conductor 11 shown in FIG. An enameled wire 10 having an insulating coating 12 on the outer circumference is obtained.

In addition, each of these steps may be performed on the same production line for part or all of the steps. Further, when the rolling process is performed multiple times, it is preferable to include an annealing process for annealing the rectangular conductor obtained by rolling between the previous rolling process and the next process.

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

(rolling process)
In the rolling process for forming the rectangular 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 or oxygen-free copper, a copper alloy having electrical conductivity equivalent to that of pure copper, or a metal such as aluminum. When the wire rod has a circular cross section, its diameter is about 8 mm or more and 12 mm or less. In addition, when the metal wire is made of low-oxygen copper, oxygen-free copper, or a copper alloy having conductivity equivalent to that of pure copper, the metal wire should be 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 wire rod 1 is rolled one or more times using a pair of rolling rolls 131a and 131b of a rolling device, thereby reducing the length a of the major axis and the length b of the minor axis. A rectangular conductor having a rectangular cross section with a ratio "a/b" of 10 or more and a minor axis length b of 0.80 mm or less is manufactured. The long axis length a of the rectangular conductor is 6 mm or more and 16 mm or less. For example, the rectangular conductor has a ratio "a/b" between the length a of the long axis and the length b of the short axis of 10 or more and 25 or less, and the length b of the short axis is 0.40 mm or more and 0.80 mm or less. It has a rectangular cross section.

Rolling rolls 131a and 131b used in the rolling process 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 rolls so that the wire rod 1 is in contact with 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 roll the wire rod 1 by rotating in the same direction about the shafts 133a and 133b. By performing such a rolling process one or more times, preferably one to three 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 length a of the major axis of the rectangular conductor 11 obtained by rolling the wire rod 1 in the rolling process. 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 length a of the major axis of the rectangular conductor 11 obtained by rolling. The depth d is the distance from the bottoms of the grooves 132a and 132b to the surfaces 134 of the rolling rolls 131a and 131b. Further, it is preferable that the depth d of the groove 132a in the rolling roll 131a and the depth d of the groove 132b in the rolling roll 131b are the same.

In addition to this, the rolling rolls 131a and 131b preferably have widths W of the grooves 132a and 132b in the portions where the wire 1 is rolled so as to satisfy 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. 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 length b of the short axis of the rectangular conductor 11. Adjust within the range of 1.25 mm or less. At this time, it is particularly preferable that the width W of the grooves 132a and 132b and the length d of the short axis of the rectangular conductor 11 satisfy the relationship W=d+0.45. The size of the width W is the maximum value when the sizes of the grooves 132a and 132b are measured along the direction orthogonal to the depth d of the grooves 132a and 132b. Moreover, it is preferable that the width W of the groove 132a in the rolling roll 131a and the width W of the groove 132b in the rolling roll 131b are the same.

Further, the grooves 132a, 132b have concave shapes recessed from the surfaces 134 of the rolling rolls 131a, 131b in the direction of the axes 133a, 133b. The concave shape includes, for example, a shape whose diameter is gradually reduced along the shafts 133a and 133b from the surfaces 134 of the rolling rolls 131a and 131b, a U shape, a tapered shape, and the like.

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

(annealing process)
In the annealing step, when the wire rod 1 that has been 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 preceding step of the next rolling step. The method of annealing the wire 1 is not particularly limited, and for example, there is a method of conveying the wire 1 inside an annealing furnace. In the annealing step, the wire rod 1 is annealed by such a method, so that working strain caused in the wire rod 1 by rolling can be reduced.

In the rolling process, after the flat conductor 11 having the flat shape shown in FIG. 1 is manufactured, the unannealed flat conductor 11 is transferred to the painting process without going through the annealing process.

(Painting process)
Subsequently, regarding the method of manufacturing the enameled wire 10, in the coating process, an insulating paint is applied to form the insulating coating 12 that covers the outer periphery of the rectangular conductor 11 formed in the rolling process.

In the method for manufacturing 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 insulation coating applied around the rectangular conductor 11 in the coating process. As such a coating die, for example, there is a die having protrusions or the like at predetermined positions facing the surface of the rectangular conductor 11 . By applying a coating die having such projections, the insulating paint applied around the rectangular conductor 11 is excessively applied, and the corners of the rectangular conductor 11 are coated due to the surface tension of the insulating paint. It is possible to prevent the coating amount of the insulating coating from decreasing. Therefore, it is possible to prevent the insulating film 12 formed around the rectangular conductor 11 from becoming uneven in thickness.

As the insulating paint applied to the outer periphery of the rectangular conductor 11, a material obtained by dissolving the resin component forming the insulating film 12 in an organic solvent can be used. For example, an insulating paint is used in which a resin such as polyimide or polyamideimide is dissolved in a polar solvent such as dimethylformamide (DMF), dimethylacetamide (DMAC), dimethylsulfoxide (DMSO), or N-methylpyrrolidone (NMP). be able to. Also, for example, an insulating paint can be used in which a resin made of formal, polyurethane, polyester, polyesterimide, or the like is dissolved in cresol, xylol, or the like.

(Heating process)
Subsequently, in the heating step, the rectangular conductor 11 coated with the insulating paint in the coating step 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, thereby hardening the insulating paint applied to the outer periphery of the rectangular conductor 11 and softening the rectangular conductor 11. In the heating step, the insulating film 12 is formed on the outer periphery of the rectangular conductor 11 by heating in this manner.

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

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

In the above-described method for manufacturing the enameled wire 10, the insulating film forming process, which includes the painting process and the heating process, is performed on a production line separate from the rolling process. 11 is less likely to be twisted. Therefore, in a manufacturing method in which such an insulating film forming process is performed on a production line separate from the rolling process, the thickness of the insulating film 12 can be easily made uniform. The enameled wire 10 having various characteristics can be manufactured more stably.

Further, in the method for manufacturing the rectangular conductor 11 or the enameled wire 10 described above, a wire rod made of a metal wire rod having a circular cross section is rolled by a rolling mill to obtain a rectangular conductor having a rectangular cross section with a large aspect ratio. Although an example of forming 11 has been shown, it is not limited to this. For example, in the method for manufacturing the rectangular 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 passed through the extruder. An extrusion step of forming a wire rod to be rolled in the rolling step by extrusion forming a rectangular cross section may be provided before the rolling step.

In the extrusion molding step, for example, a metal wire having a diameter of approximately 8 mm or more and 12 mm or less and a circular cross section is extruded by an extruder into a wire having a rectangular cross section. This extruded wire rod becomes a wire rod for rolling. When the metal wire is made of pure copper such as tough pitch copper or oxygen-free copper, the wire is extruded in the form of an annealed copper wire from an extruder. Then, in the rolling step, the wire having a rectangular cross section is rolled using rolling rolls shown in FIG. is 10 or more (for example, 10 or more and 25 or less) and the short axis length b 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 enameled wire 10 according to the present embodiment, by including the extrusion process described above, it is possible to reduce the number of rolling processes, and the reduction in the number of annealing processes associated with the reduction in the number of rolling processes. That is, in the method for manufacturing the rectangular conductor 11 or the enameled wire 10 according to the present embodiment, further improvement in production efficiency can be expected by combining the above-described extrusion molding process and rolling process.

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

In the case of manufacturing a rectangular conductor 11 having a rectangular cross section with a large aspect ratio by repeating the rolling process without using the rolling rolls shown in FIG. 3 and the annealing process multiple times, the rolling rolls shown in FIG. It is possible to obtain an enamelled wire 10 having the properties described above, as with the use. However, when the rolling rolls shown in FIG. 3 are not used, the number of steps increases compared to the case where the rolling rolls shown in FIG. 3 are used. Therefore, from the viewpoint of improving production efficiency, the method of manufacturing an enameled wire that includes a rolling process using rolling rolls shown in FIG. 3 is preferable.

[Effects of this embodiment]
According to this embodiment, the rectangular cross section has a ratio "a/b" between the major axis length a and the minor axis length b of 10 or more and the minor axis length b of 0.80 mm or less. An enameled wire having an elongation of 40% or more, a tensile strength of 280 MPa or more, and a 0.2% yield strength of 65 MPa or more, comprising a rectangular conductor 11 having a surface and an insulating coating 12 coated on the outer periphery of the rectangular conductor 11. As a result, in an enameled wire having a large aspect ratio, it is possible to prevent the insulating coating 12 from cracking due to edgewise bending during coil forming.

Further, according to the present embodiment, by rolling the wire using 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 of the minor axis A rolling step of forming a rectangular conductor having a rectangular cross section with a width b of 0.80 mm or less, and an insulating coating forming step of forming an insulating coating coated on the outer periphery of the rectangular conductor, 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 rectangular conductor obtained by rolling, and a depth The wire rod is rolled by passing through rolling rolls having a groove having a width W that satisfies 2≤d/W≤6 in relation to d, and the wire rod is in contact with the inner surface of the groove. As a result, in the method for manufacturing an enameled wire according to the present embodiment, the stress applied to the wire is reduced so as not to break the wire at the central portion of the long axis when the wire is rolled by the rolling rolls, and The workability of the wire can be increased. As a result, in the method for manufacturing an enameled wire according to the present embodiment, the number of rolling steps and annealing steps can be reduced. Enameled wire 10 having conductor 11 can be efficiently manufactured.

That is, according to this embodiment, the rectangular conductor 11 has an aspect ratio of 10:1 or more and a minor axis length of 0.80 mm or less, and the insulating coating 12 is effective against edgewise bending during coil molding. Therefore, 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 can be used, for example, as a driving motor used in EV (Electric Vehicle) or HEV (Hybrid Electric Vehicle), a DC boost coil used in solar power generation, or as a noise countermeasure for electrical equipment. It is suitable for reactor coils used in applications such as

In sample 1 shown in Table 1, a wire rod made of tough pitch copper (diameter: 12 mm) having a circular cross section was extruded into a rectangular cross section using an extruder, and then the roll shown in FIG. Groove depth d: 3.50 mm, groove width W: 1.15 mm), the major axis length a is 14 mm, the minor axis length b is 0.70 mm, and the corner curvature A rectangular conductor having a rectangular cross section with a radius of 0.30 mm was produced. Next, the outer circumference of the rectangular conductor is coated with an insulating coating made of an insulating resin made of polyimide to which an additive for improving adhesion is added, and heating is repeated twice to form a first insulating film. By repeating a painting step of applying an insulating paint containing a resin of an insulated wire made of polyamide-imide on the outer circumference of the first insulating film and a heating step of heating a rectangular conductor containing the painted insulating paint, a second was formed and wound by a winder to manufacture an enameled wire having an insulation coating (first insulation coating/second insulation coating) having a thickness of 40 μm.

In sample 2 shown in Table 1, a wire rod made of tough pitch copper (diameter: 12 mm) having a circular cross section was rolled (groove depth d: 1.50 mm or less, groove width W: 2.80 mm or less). to produce a rectangular conductor having a rectangular cross section with a major axis length a of 14 mm, a minor axis length b of 0.70 mm, and a corner curvature radius of 0.30 mm. bottom. Note that sample 2 was annealed in an annealing furnace when rolling was performed multiple times. Next, the outer circumference of the rectangular conductor is coated with an insulating coating made of an insulating resin made of polyimide to which an additive for improving adhesion is added, and heating is repeated twice to form a first insulating film. The second insulating film is formed by repeating a step of applying an insulating paint containing an insulating resin made of polyamide-imide on the outer circumference of the first insulating film and a heating step of heating the rectangular conductor containing the painted insulating paint. was formed and wound by a winder to manufacture an enameled wire having an insulation coating (first insulation coating/second insulation coating) having a thickness of 43 μm.

In Table 1 below, the properties and the like of the enameled wires of Samples 1 and 2 were evaluated. Table 1 shows the results of evaluation of elongation, tensile strength, 0.2% yield strength, edgewise bending, and productivity as properties of the enameled wire.

(Elongation rate, tensile strength, 0.2% yield strength)
In Table 1, the elongation rate and tensile strength of the enameled wire were measured by performing a tensile test according to JIS C3216-3 with an insulating film around the rectangular conductor. In addition, the 0.2% yield strength of the enameled wire is the stress-strain curve obtained when measuring the elongation rate and tensile strength described above. When a straight line parallel to the tangent is drawn from the position where the strain is 0.2% - determine the point (intersection) where the strain curve and the straight line intersect, and measure the stress at this intersection as a 0.2% proof stress bottom.

(edgewise bending)
In Table 1, the edgewise bending of the enameled wire was measured according to JIS C3216-3 JA. Tested by the method according to 5.1.2 a). In this test, the enameled wire was bent edgewise by 180 degrees while the surface of the insulating film located in the direction of the long axis of the enameled wire was in contact with the surface of a mandrel having a diameter of 16 mm. It was evaluated whether or not cracks would occur in the insulating coating.

(Productivity)
In Table 1, the productivity was evaluated by the number of times of rolling when producing rectangular conductors in the rolling process.

As shown in Table 1, in the enameled 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. A rectangular conductor having a rectangular cross section of .80 mm or less is provided with an insulating coating on its outer periphery, and in a state in which the rectangular conductor has an insulating coating on its outer periphery, the elongation is 40% or more and the tensile strength is 280 MPa or less. The 0.2% yield strength is 65 MPa or more. By using such an enameled wire, the insulating film coated on the outer periphery of the 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 edged. It can be seen that cracks are less likely to occur when wisely bent. In the case of the enameled wires of Samples 1 and 2, when the edgewise bending described above is performed, the portion to be bent (the portion to be bent 180 degrees) does not have 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 method of manufacturing an enamelled wire (method of manufacturing sample 1) including the rolling step using the rolling rolls shown in FIG. It can be seen that the productivity is superior (that is, the production efficiency is high) to that of the wire manufacturing method (the manufacturing method of sample 2).

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention.

The embodiments described above do not limit the claimed invention. Also, it should 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 Enameled wire 11 Rectangular conductor 12 Insulating film

Claims (3)

A wire rod made of rolled tough-pitch copper, having a major axis length a that is the length between two opposing short sides and a minor axis length that is the length between two opposing long sides Rectangular shape in which the ratio "a/b" to b is 10 or more and 25 or less , the length b of the short axis is 0.40 mm or more and 0.80 mm or less, and the length a of the long axis is 6 mm or more and 16 mm or less a rectangular conductor having a cross section of
A first insulating film made of an insulating resin made of polyimide and coated on the outer periphery of the rectangular conductor, and a first insulating film made of an insulating resin made of polyamideimide formed around the first insulating film. and a second insulating film consisting of
Elongation rate is 40% or more, tensile strength is 280 MPa or less, and 0.2% proof stress is 65 MPa or more when a tensile test is performed by a method conforming to JIS C3216-3 with the insulating film around the rectangular conductor. and
In a state in which the insulating coating is provided around the rectangular conductor, when the surface of the insulating coating is in contact with the surface of a mandrel having a diameter of 16 mm and is bent in the direction of the long axis, the bent portion is the short axis. Enameled wire that bends 180 degrees without bending in the direction of The first insulating film is added with an additive that improves adhesion with the rectangular conductor.
The enameled wire according to claim 1 . In the state of having the insulating film around the flat conductor, the surface of the insulating film is in contact with the surface of a mandrel having a diameter of 16 mm using a method conforming to JIS C3216-3. sometimes the insulating coating does not crack,
The enameled wire according to claim 1 or 2 .

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