JP6798193B2 - Insulated wire and its manufacturing method - Google Patents

Description

The present invention relates to an insulated electric wire and a method for manufacturing the same.

Coil is built into electric equipment such as rotary electric machines (motors) and transformers. The coil is formed by winding an insulated electric wire having an insulating coating formed on the outer circumference of a conductor. Insulated electric wires can be made by applying and baking an insulating paint in which a resin component is dissolved in an organic solvent on the outer periphery of a conductor, extruding the melted resin onto the outer periphery of a conductor, or by using these methods in combination. , It is manufactured by forming an insulating coating on the outer periphery of a conductor.

In recent years, motors used in automobiles and the like have been required to have higher capacity and smaller size, and the coil incorporated in the motor has a space factor (ratio of the cross-sectional area of the conductor to the cross-sectional area of the coil) and heat dissipation. Improvement of sex is required.

Therefore, as the insulated wire forming the coil, a flat wire using a flat conductor having a rectangular cross section has been used (see, for example, Patent Document 1). When a coil is manufactured using a flat wire, the coil is manufactured by bending the flat wire in the width direction, performing edgewise processing, and winding the coil.

JP-A-2002-203438

For the flat wire, in order to further improve the space factor and heat dissipation of the coil, it is considered to use a flat conductor having a higher aspect ratio with a larger width than the thickness.

However, since edgewise processing is performed in the width direction in which the flat wire is difficult to bend, it becomes difficult to wind the coil with a small bending radius as the aspect ratio of the flat conductor becomes larger and the width becomes wider. Further, even if the coil is manufactured, the bending strain becomes large on the outer peripheral side of the coil, so that the surface of the flat conductor or the insulating coating is cracked, and it becomes difficult to secure the desired insulating property. Therefore, these may become restrictions in realizing high capacity and miniaturization of the motor.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an insulated electric wire having a large aspect ratio and a wide width, which is hard to break when edgewise processed.

According to one aspect of the invention
A flat conductor made of a copper material having a rectangular cross section and an insulating coating provided on the outer periphery of the flat conductor and formed of a thermosetting resin are provided.
The flat conductor has a width ratio to a thickness of 10 or more.
The copper material has a titanium concentration of 5 mass ppm or more and 55 mass ppm or less, a sulfur concentration of 3 mass ppm or more and 12 mass ppm or less, an oxygen concentration of 2 mass ppm or more and 30 mass ppm or less, and the balance is copper and unavoidable impurities. An insulated wire having a concentration ratio of 2.0 or more and 4.0 or less is provided.

According to another aspect of the invention
A rolling process in which a copper alloy wire made of a copper material is rolled to form a flat conductor having a rectangular cross section.
A heating step for heating the flat conductor and
It has a coating step of coating the outer periphery of the heated flat conductor with an insulating coating formed of a thermosetting resin.
The copper material has a titanium concentration of 5 mass ppm or more and 55 mass ppm or less, a sulfur concentration of 3 mass ppm or more and 12 mass ppm or less, an oxygen concentration of 2 mass ppm or more and 30 mass ppm or less, and the balance is copper and unavoidable impurities. The concentration ratio is 2.0 or more and 4.0 or less,
In the rolling step, a method for manufacturing an insulated electric wire is provided in which the copper alloy wire is rolled so that the ratio of the width to the thickness of the flat conductor is 10 or more.

According to the present invention, it is possible to obtain an insulated wire having a large aspect ratio and a wide width, which is hard to break when edgewise processed.

It is sectional drawing perpendicular to the length direction of the insulated wire which concerns on one Embodiment of this invention. It is a perspective view of the coil manufactured using the insulated wire which concerns on one Embodiment of this invention.

The insulated wire according to the embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view perpendicular to the length direction of the insulated wire according to the embodiment of the present invention. FIG. 2 is a perspective view of a coil manufactured by using the insulated wire according to the embodiment of the present invention. The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

As shown in FIG. 1, the insulated wire 1 of the present embodiment is configured to include a flat conductor 11 and an insulating coating 12, and is bent in the width direction and edgewise processed as shown in FIG. It is formed in.

The flat conductor 11 is a conductor formed by rolling a copper alloy wire made of a copper material, for example, a circular conductor having a circular cross section so as to have a rectangular cross section, so that the width becomes larger with respect to the thickness. .. In the present embodiment, the width ratio to the thickness (hereinafter, also referred to as an aspect ratio) is formed to be 10 or more.

In the conventional insulated wire, when the flat conductor is widely configured so that the aspect ratio is 10 or more in order to further improve the space factor and heat dissipation in the coil, the stress when rolling the circular conductor into a rectangular shape is increased. The high stress rolling can cause scratches on the surface of the flat conductor. If the surface of the flat conductor is scratched, defects such as voids are likely to occur in the insulating coating when the insulating coating is formed, and the insulating coating may be cracked when the insulated wire is processed into a coil. Further, when the conventional insulated wire is edgewise processed to form a coil, bending strain becomes large on the outer peripheral side of the coil, and there is a possibility that the surface of the flat conductor or the insulating coating may be cracked. As a result of studies by the present inventors on a method for solving this problem, the copper material constituting the flat conductor 11, that is, the copper material constituting the circular conductor used for forming the flat conductor 11, is an impurity sulfur (S). ) And oxygen (O) should be reduced, and a small amount of titanium (Ti) should be added to keep the ratio of the titanium concentration to the oxygen concentration within a predetermined range. Specifically, the copper material has a titanium concentration of 5 mass ppm or more and 55 mass ppm or less, a sulfur concentration of 3 mass ppm or more and 12 mass ppm or less, and an oxygen concentration of 2 mass ppm or less.
It is 30 mass ppm or less, the balance is composed of copper and unavoidable impurities, and the ratio of titanium concentration to oxygen concentration is 2.0 or more and 4.0 or less.

Such a copper material has a purity similar to that of oxygen-free copper (OFC) (4N: 99.99% or more), but by containing a predetermined amount of Ti, high-purity copper with higher purity It has a semi-softening temperature similar to (6N: 99.9999% or more). Specifically, this copper material has a semi-softening temperature of 150 ° C. or lower (for example, about 130 ° C.), a semi-softening temperature lower than the OFC semi-softening temperature (about 220 ° C.), and is made of high-purity copper. It has a semi-softening temperature similar to the semi-softening temperature (about 130 ° C.). According to this copper material, the heating temperature at the time of annealing for recrystallization can be lowered, so that it becomes possible to suppress the coarsening of copper crystal grains due to heating at the time of recrystallization, and OFC. If the heating temperature is the same, it can be made softer. The semi-softening temperature is defined as the tensile strength at room temperature after a 2.6 mm hard copper wire obtained by cold-working a cast and rolled material is immersed in a salt bath at 100 to 500 ° C. and heated for 1 hour. It is a heating temperature at which the tensile strength drops to a value intermediate between the value of the tensile strength before heating and the value of the tensile strength after 1 hour.

Further, this copper material has a higher elongation rate than OFC or high-purity copper even when heated (annealed) at a high temperature (for example, 500 ° C.) higher than the semi-softening temperature in order to improve processability. It can be high and the yield strength can be lowered by 0.2%. In OFC and the like, the copper crystal grains are coarsened by annealing at a high temperature to form a coarse crystal structure, which impairs the elongation rate and 0.2% proof stress. On the other hand, since the copper material of the present embodiment contains Ti, coarsening of copper crystal grains is suppressed even when annealed at a high temperature, and a fine crystal structure can be maintained, so that the elongation rate is high. Moreover, it is possible to maintain a low 0.2% proof stress. Therefore, since the circular conductor formed from the copper material of the present embodiment has a high elongation rate and a low proof stress of 0.2%, stress during rolling can be reduced and scratches on the surface of the flat conductor 11 can be suppressed. it can. Moreover, since the flat conductor 11 formed by rolling is made of a copper material having a high elongation rate and a low proof stress of 0.2%, it is difficult to crack due to bending strain when the insulated wire 1 is edgewise processed. Become.

The copper material constituting the circular conductor for forming the flat conductor 11 preferably has an elongation rate of 25% or more from the viewpoint of suppressing scratches on the surface of the flat conductor 11 when rolled. The 2% proof stress is preferably 80 MPa or less, and more preferably 70 MPa or less. By using such a copper material for a circular conductor, the elongation rate and 0.2% proof stress of the copper material constituting the flat conductor 11 can be adjusted within the above ranges, and the insulated wire 1 is made into a coil by edgewise processing. It is possible to suppress cracking when it is formed. The elongation rate can be expressed by the following equation, where L0 is the initial reference point distance of the tensile test piece and L is the same distance after fracture. Elongation rate = {(L-L0) / L0} x 100 [%]). The 0.2% proof stress is the stress that causes 0.2% plastic strain when the load is unloaded on the stress-strain curve.

As described above, since the flat conductor 11 of the present embodiment is formed from the copper material, it can have a high elongation rate and a low 0.2% proof stress when annealed at a high temperature, while having a fine crystal structure. Can be maintained. In the fine crystal structure, processing strain (bending strain, etc.) is easily dispersed, and cracks are less likely to occur. That is, the flat conductor 11 is flexible and easily stretched by annealing, and is less likely to crack due to processing strain. Therefore, when the insulated wire 1 is edgewise processed to produce the coil 2, cracking due to bending strain in the flat conductor 11 can be suppressed. On the other hand, a conductor made of OFC or the like becomes brittle as the elongation decreases because the crystal grains become coarse and the crystal structure becomes coarse due to annealing at a high temperature. Moreover, the copper crystal grains become coarse and the crystal structure becomes coarse, so that the elongation at the time of edgewise processing becomes non-uniform. Therefore, a conductor made of OFC or the like is likely to be cracked due to bending strain.

The aspect ratio of the flat conductor 11 is preferably larger from the viewpoint of the space factor of the coil 2 and the heat dissipation. In the present embodiment, since the flat conductor 11 is formed of the copper material, even if the aspect ratio is 10 or more, preferably 20 or more, cracking when the insulated wire 1 is edgewise processed can be suppressed. Although the upper limit value is not particularly limited, it is preferably 30 or less, and more preferably 25 or less, from the viewpoint of workability when the insulated wire 1 is edgewise processed.

The thickness and width of the flat conductor 11 are not particularly limited as long as the aspect ratio is within a predetermined range, but the thickness may be, for example, 0.5 mm to 1.0 mm, and the width may be, for example, 5 mm to 25 mm. Good.

The insulating coating 12 is provided on the outer periphery of the flat conductor 11. The insulating coating 12 is formed of a thermosetting resin, preferably from at least one of polyimide, polyamide-imide and polyesterimide, for example. For example, the insulating coating 12 can be formed by applying a resin coating material in which a resin component is dissolved in an organic solvent on the outer periphery of a flat conductor 11 and baking the coating.

The thickness of the insulating coating 12 is not particularly limited, and may be appropriately changed according to the electrical characteristics required for the insulated wire 1.

Next, the method of manufacturing the above-mentioned insulated wire 1 will be described. The manufacturing method of the present embodiment includes a preparation step, a rolling step, a heating step, and a coating step.

First, in the preparation process, the titanium concentration of the copper alloy wire is 5 mass ppm or more and 55 ma.
ss ppm or less, sulfur concentration 3 mass ppm or more and 12 mass ppm or less, oxygen concentration 2 mass ppm or more and 30 mass ppm or less, the balance is composed of copper and unavoidable impurities, and the ratio of titanium concentration to oxygen concentration is 2.0 or more and 4.0 or less. Prepare a circular conductor made of a copper material. As the circular conductor, for example, a rough drawn wire made of the copper material whose diameter is reduced by drawing can be used. From the viewpoint of reducing the rolling stress in the rolling process described later, this circular conductor is formed of a copper material having a predetermined composition, an elongation rate of 25% or more, and a 0.2% proof stress of 80 MPa or less. Is preferable.

Subsequently, in the rolling step, the circular conductor is rolled so that the cross section has a rectangular shape. At this time, rolling is performed so that the length of the long side of the rectangular shape is 10 times or more the length of the short side. As a result, a flat conductor 11 having a rectangular cross section and an aspect ratio of 10 or more is obtained.

Subsequently, in the heating step, the flat conductor 11 is heated. As a result, the flat conductor 11 is annealed to remove the processing strain generated in the flat conductor 11 in the rolling process and recrystallized, thereby increasing the elongation rate and lowering the 0.2% proof stress. As described above, the copper material constituting the flat conductor 11 has a low S concentration and an O concentration, and the Ti concentration has a predetermined ratio with respect to the O concentration. Therefore, when the flat conductor 11 is heated, it is possible to suppress the coarsening of crystal grains in the copper material constituting the flat conductor 11. As a result, processing strain can be removed and recrystallization can be performed without impairing the elongation rate and 0.2% proof stress of the flat conductor 11.

The heating conditions in the heating step are preferably changed as appropriate so that the elongation rate of the copper material constituting the flat conductor 11 is 25% or more and the 0.2% proof stress is 80 MPa or less. For example, the heating temperature may be 400 ° C. to 600 ° C. and the heating time may be 30 seconds to 120 seconds.

Subsequently, in the coating step, the insulating coating 12 is formed by applying and baking a resin coating material in which a resin component is dissolved in an organic solvent on the outer periphery of the flat conductor 11 after the heating step. As the resin coating material, a polyimide coating material, a polyamide-imide coating material and a polyesterimide coating material may be used, and it is preferable that the insulating coating 12 is formed of at least one of polyimide, polyamide-imide and polyesterimide.

From the above, the insulated wire 1 of the present embodiment is manufactured.

In the insulated wire 1 of the present embodiment, the flat conductor 11 is formed of a copper material having a low S concentration and an O concentration and a ratio of the Ti concentration to the O concentration of 2.0 to 4.0, and its aspect ratio thereof. Is 10 or more. By setting the copper material to a predetermined composition, the semi-softening temperature can be lowered, and the flat conductor 11 can be annealed at a low temperature. The flat conductor 11 is annealed at a low temperature to increase the elongation rate and reduce the 0.2% proof stress, while suppressing the coarsening of copper crystal grains to maintain a fine crystal structure. Can be done. That is, the flat conductor 11 is flexible and easily stretchable, and can be made hard to crack due to processing strain (bending strain, etc.). As a result, even when the insulated wire 1 having the flat conductor 11 having a wide aspect ratio of 10 or more is edgewise processed, cracking in the flat conductor 11 and the insulating coating 12 can be suppressed. Therefore, the coil 2 produced by edgewise processing the insulated wire 1 has a high space factor and heat dissipation, and the flat conductor 11 and the insulating coating 12 are not cracked to ensure the insulating property.

Next, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

<Manufacturing of insulated wires>
(Example 1)
First, as a copper alloy wire for forming a flat conductor, a circular conductor having a composition shown in Table 1 below and having a circular cross section was prepared. This circular conductor is rolled using a rolling mill so that the cross section has a rectangular shape, and a flat conductor having a width of 6 mm, a thickness of 0.6 mm, and a width ratio (aspect ratio) of 10 to the thickness is obtained. Made. Then, the produced flat conductor was heated at a temperature of 550 ° C. and annealed. Then, a polyimide paint was applied to the outer periphery of the annealed flat conductor and baked to form an insulating coating having a thickness of 50 μm. As a result, the insulated wire of Example 1 was obtained.

(Examples 2 to 4, Comparative Examples 1 to 4)
In Examples 2 to 4 and Comparative Examples 1 to 4, the ratio of Ti concentration / O concentration in the flat conductor and the width, thickness and aspect ratio of the flat conductor were changed as shown in Table 1, except that Example 1 An insulated wire was produced in the same manner as in the above.

<Evaluation method>
Each insulated wire produced was evaluated by the following method.

(Edgewise bending)
A round bar having a predetermined outer diameter is prepared, the insulated wire is brought into contact with the edge surface so as to be orthogonal to the outer circumference of the round bar, and the central portion of the insulated wire brought into contact with the round bar while being kept in one plane is edged. Bent 180 ° wisely. At this time, it was visually observed whether the flat conductor was exposed and cracked in the insulating coating of the insulated wire bent at 180 °. In this embodiment, when the width of the flat conductor is d, the diameter of the round bar is 4d, the insulated wire is bent edgewise, and the flat conductor and the insulating coating are excellent in workability if there are no defects such as cracks. Judging that ○, bending the round bar edgewise with a diameter of 3d, if no defects such as cracks occur, it is judged to be superior in workability ◎, otherwise it is judged to be inferior in workability. It was marked as x.

(Growth rate)
A circular conductor before rolling is separately prepared as a test piece, a tensile test is performed with a gauge point distance (L0) of 250 mm and a tensile speed of 100 mm / min or less, and the test pieces after fracture are butted against each other to perform a gauge point distance (L). ) Was calculated, and the elongation rate was calculated by the following formula. Elongation rate = {(L-L0) / L0} x 100 [%]).

(0.2% proof stress)
A circular conductor before rolling is prepared separately as a test piece, and a tensile test similar to the elongation rate is performed. In the stress-strain curve, 0.2% of the strain axis and 0 (zero) stress are used to obtain the elastic modulus. A line was drawn in parallel and the stress at the intersection with the stress-strain curve was calculated as 0.2% proof stress.

<Evaluation result>
The evaluation results are shown in Table 1.
As shown in Table 1, in Examples 1 to 4, the aspect ratio of the flat conductor is set to 10 or more in order to increase the space factor and the heat dissipation, but the S concentration and the O concentration in the flat conductor are lowered and Ti. It was confirmed that by setting the concentration / O concentration ratio within the range of 2.0 to 4.0, cracking can be prevented by edgewise processing. In particular, in Examples 2 to 4, the aspect ratio is as high as 20 or more, but it was confirmed that the edgewise processing can prevent cracks from occurring by setting the flat conductor to a predetermined composition. The reason why cracking due to edgewise processing could be suppressed is that the copper material of the flat conductor contained a small amount of Ti, which suppressed the coarsening of crystal grains when annealed and maintained the fine crystal structure of copper. It is thought that it was possible.

On the other hand, in Comparative Examples 1 to 4, since the Ti concentration / O concentration ratio in the flat conductor was set to be out of the range of 2.0 to 4.0, the semi-softening temperature of the flat conductor was high and the annealing temperature was set. I had to make it higher. Therefore, in Comparative Examples 1 to 4, it was confirmed that the crystal grains were coarsened by annealing at a high temperature, and cracks due to edgewise processing were likely to occur.

As described above, in the present invention, the aspect ratio of the flat conductor is formed by adding a small amount of Ti so that the Ti concentration / O concentration ratio is 2.0 to 4.0 in the copper material forming the flat conductor. It was confirmed that bending distortion due to edgewise processing can be suppressed even when the value is increased.

<Preferable Aspect of the Present Invention>
Hereinafter, preferred embodiments of the present invention will be added.

[Appendix 1]
According to one aspect of the invention
A flat conductor made of a copper material having a rectangular cross section and an insulating coating provided on the outer periphery of the flat conductor and formed of a thermosetting resin are provided.
The flat conductor has a width ratio to a thickness of 10 or more.
The copper material has a titanium concentration of 5 mass ppm or more and 55 mass ppm or less, a sulfur concentration of 3 mass ppm or more and 12 mass ppm or less, an oxygen concentration of 2 mass ppm or more and 30 mass ppm or less, and the balance is copper and unavoidable impurities. An insulated wire having a concentration ratio of 2.0 or more and 4.0 or less is provided.

[Appendix 2]
In the insulated wire of Appendix 1, preferably
The copper material has a semi-softening temperature of 150 ° C. or lower.

[Appendix 3]
In the insulated wire of Appendix 1 or 2, preferably
The thermosetting resin is at least one of polyimide, polyamide-imide and polyesterimide.

[Appendix 4]
According to another aspect of the invention
A rolling process in which a copper alloy wire made of a copper material is rolled to form a flat conductor having a rectangular cross section.
A heating step for heating the flat conductor and
It has a coating step of coating the outer periphery of the heated flat conductor with an insulating coating formed of a thermosetting resin.
The copper material has a titanium concentration of 5 mass ppm or more and 55 mass ppm or less, a sulfur concentration of 3 mass ppm or more and 12 mass ppm or less, an oxygen concentration of 2 mass ppm or more and 30 mass ppm or less, and the balance is copper and unavoidable impurities. The concentration ratio is 2.0 or more and 4.0 or less,
In the rolling step, a method for manufacturing an insulated electric wire is provided in which the copper alloy wire is rolled so that the ratio of the width to the thickness of the flat conductor is 10 or more.
[Appendix 5]
In the method for manufacturing an insulated wire of Appendix 4, preferably
The copper material has an elongation rate of 25% or more and a 0.2% proof stress of 55 MPa or less.

1 Insulated wire 2 Coil 11 Flat conductor 12 Insulated coating

Claims (4)

A flat conductor made of a copper material having a rectangular cross section and an insulating coating provided on the outer periphery of the flat conductor and formed of a thermosetting resin are provided.
The flat conductor has a width ratio to a thickness of 10 or more.
The copper material has a titanium concentration of 26 mass ppm or more and 40 mass ppm or less, a sulfur concentration of 3 mass ppm or more and 4 mass ppm or less, an oxygen concentration of 10 mass ppm or more and 13 mass ppm or less, and the balance consisting of copper and unavoidable impurities. An insulated wire having a ratio of the titanium concentration to an oxygen concentration of 2.0 or more and 4.0 or less , an elongation rate of 25% or more, and a 0.2% withstand power of 80 MPa or less . The insulated wire according to claim 1, wherein the copper material has a semi-softening temperature of 150 ° C. or lower. The insulated wire according to claim 1 or 2, wherein the thermosetting resin is at least one of polyimide, polyamide-imide, and polyesterimide. A rolling process in which a copper alloy wire made of a copper material is rolled to form a flat conductor having a rectangular cross section.
A heating step of heating the flat conductor at a heating temperature of 400 ° C. to 600 ° C. for 30 seconds to 120 seconds , and
It has a coating step of coating the outer periphery of the heated flat conductor with an insulating coating formed of a thermosetting resin.
The copper material has a titanium concentration of 26 mass ppm or more and 40 mass ppm or less, a sulfur concentration of 3 mass ppm or more and 4 mass ppm or less, an oxygen concentration of 10 mass ppm or more and 13 mass ppm or less, and the balance is copper and unavoidable impurities. The ratio of the titanium concentration to the oxygen concentration is 2.0 or more and 4.0 or less, the elongation rate is 25% or more, the 0.2% strength is 80 MPa or less, and in the rolling step, the width with respect to the thickness of the flat conductor. A method for manufacturing an insulated electric wire, in which the copper alloy wire is rolled so that the ratio of

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