INSULATED ELECTRIC WIRE AND METHOD FOR MANUFACTURING SAME

Abstract

An insulated electric wire and a method of producing the electric wire are provided. The insulated electric wire includes: a copper wire; and an insulating coating formed on a surface of the copper wire by an electrodeposition method. A cross section shape of the insulated electric wire including the insulating coating is in a hexagonal shape, a chamfered part that suppresses swelling of the insulating coating is formed on each corner part of a hexagonal cross section of the copper wire, a length of the chamfered part is 1/3 to 1/20 of a length of a flat part of the hexagonal cross section, and a void ratio in a wound state is 5% or less.

Claims

1. An insulated electric wire comprising: a copper wire; and an insulating coating formed on a surface of the copper wire by an electrodeposition method, wherein a cross section shape of the insulated electric wire including the insulating coating is in a hexagonal shape, a chamfered part that suppresses swelling of the insulating coating is formed on each corner part of a hexagonal cross section of the copper wire, a length of the chamfered part is 1/3 to 1/20 of a length of a flat part of the hexagonal cross section, and a void ratio in a wound state is 5% or less.

2. The insulated electric wire according to claim 1, wherein a difference between: a thickness of the insulating coating on the flat part of the hexagonal cross section of the insulated electric wire; and a thickness of the insulating coating on the corner part of the insulated electric wire including the chamfered part, is 5 μm or less.

3. The insulated electric wire according to claim 1, wherein a diameter of the hexagonal cross section of the copper wire converted to a circle having an identical cross sectional area to the hexagonal cross section of the copper wire is 0.5 mm to 5.0 mm, and a thickness of the insulating coating is 5 μm to 100 μm.

4. A method of producing an insulated electric wire by an electrodeposition method, the method comprising the steps of: electrodepositing a coating component on a surface of a copper wire to be a core material by the copper wire being passed through an electrodeposition bath filled with an electrodepositing solution including the coating component and by applying electrical current; and forming an insulating coating by performing a baking process on the coating component after the step of electrodepositing, wherein the cooper wire used in the step of electrodepositing a coating component has a hexagonal cross section, a chamfered part is formed on each corner part of the hexagonal cross section of the copper wire, and a length of the chamfered part is 1/3 to 1/20 of a length of a flat part of the hexagonal cross section, a difference between: a thickness of the insulating coating on the flat part of the hexagonal cross section of the insulated electric wire; and a thickness of the insulating coating on the corner part of the insulated electric wire including the chamfered part, is 5 μm or less, and an insulated electric wire having a void ratio in a wound state is 5% or less is produced.

5. The method of producing an insulated electric wire according to claim 4, wherein the copper wire used in the step of electrodepositing a coating component has a diameter of the hexagonal cross section of the copper wire converted to a circle having an identical cross sectional area to the hexagonal cross section of the copper wire is 0.5 mm to 5.0 mm, and the insulating coating formed on the surface of the copper wire in the step of forming an insulating coating has a thickness of 5 to 100 μm.

6. The insulated electric wire according to claim 2, wherein a diameter of the hexagonal cross section of the copper wire converted to a circle having an identical cross sectional area to the hexagonal cross section of the copper wire is 0.5 mm to 5.0 mm, and a thickness of the insulating coating is 5 μm to 100 μm.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0050] FIG. 1 is a schematic cross sectional view of the insulated electric wire of the present invention.

[0051] FIG. 2 is a partial schematic sectional view of the chamfered part of the insulated electric wire of the present invention.

[0052] FIG. 3 is a schematic cross sectional view showing the wound state of the insulated electric wire of the present invention.

[0053] FIG. 4 is an enlarged cross sectional photograph of the insulated electric wire B of Example 1.

[0054] FIG. 5 is a schematic cross sectional view showing the wound part of the conventional insulated electric wire formed by the electrodeposition method.

DESCRIPTION OF EMBODIMENTS

Example 1

[0055] After preparing the intermediate copper wire by using a round copper hard wire having 1.1 mm of the outer diameter φ with pressure rollers, the hexagonal cross section, which had 0.3 mm of the flat part length of each side; and 0.1 mm of the chamfered part length, was formed by drawing it through the finish die. The copper wire with the hexagonal cross section was passed through the electrodeposition bath filled with the electrodeposition solution including polyimide, which was the resin component of the coating; and the resin coating was attached on the surface of the copper wire by applying electrical current using the copper wire as the anode. By varying the electrical current density, two kinds of resin coatings with the layer thicknesses of 5 μm and 10 μm were formed. The insulated electric wire A, the minimum thickness of the coating of the flat part was 5 μm, and the insulated electric wire B, the minimum thickness of the coating of the flat part was 10 μm, were produced by inserting them in a furnace for drying; and by performing the baking treatment in the furnace with the setting of 200° C. to 500° C. of the temperature gradient. On these insulated electric wires A and B, the differences D between the minimum thickness Ds of the insulating coating on the flat part and the maximum thickness Dm of the insulating coating on the corner part; and the void ratios in the wound state are shown in Table 1. The cross sectional photograph of the insulated electric wire B is shown in FIG. 4.

Example 2

[0056] The insulated electric wires C to J were produced: by using the copper wires processed in such a way that the length L of the flat part of the hexagonal cross section and the length R of the chamfered part are set as shown in Table 1; and by forming the insulating coatings by the electrodeposition method as in Example 1. On these insulated electric wires C to J, the differences D between the minimum thickness Ds of the insulating coating on the flat part and the maximum thickness Dm of the insulating coating on the corner part; and the void ratios in the wound state are shown in Table 1.

Comparative Example 1

[0057] A round copper hard wire having 0.1 mm of the outer diameter φ was passed through pressure rollers; and processed by drawing through a finish die.

[0058] At this time, the chamfered part was not provided to the finish die, and the copper wire was processed into a hexagonal cross section. The insulated electric wire X was produced by using this copper wire having the hexagonal cross section and by the electrodeposition method as the insulated electric wire B in Example 1. Results are shown in Table 1.

Comparative Example 2

[0059] The insulated electric wire Y was produced by using the round copper hard wire having 1.0 mm of the outer diameter φ as it is with the round cross section without being processed into the hexagonal cross section and by the electrodeposition method as in the insulated electric wire B in Example 1 except for the above-described difference. Results are shown in Table 1.

Comparative Example 3

[0060] Round copper hard wires having 3.0 mm and 5.0 mm of the outer diameters φ, were passed through pressure rollers; and processed by drawing through a finish die. At this time, the chamfered part was not provided to the finish die, and the copper wires were processed into a hexagonal cross section. The insulated electric wires Z1 and Z2 were produced by using the above-described cooper wires and by forming the insulating coatings by the electrodeposition method as in Example 1. Results are shown in Table 1.

Comparative Example 4

[0061] A round copper hard wire having 3.0 mm of the outer diameter φ was passed through pressure rollers; and processed by drawing through a finish die in such a way that the ratio R/L became 1/2 or 1/30. The insulated electric wires Z3 and Z4 were produced by using the above-described copper wires and by forming the insulating coatings by the electrodeposition method as in Example 1. Results are shown in Table 1.

[0062] As shown in Table 1, the void ratios were 5% or less in any one of the insulted electric wires A to J of the present invention; and the void ratios in the wound state were extremely low by proving the chamfered part on the corner part. On the other hand, in any one of the insulated electric wires X, Z1 and Z2, which were not provided with the chamfered part; and the insulated electric wire Y in the round cross section, the void ratios in the wound state were high and 7% to 12%. In addition, in the insulated electric wires Z3 and Z4 in which the ratios of the length R of the chamfered part and the length L of the flat part were set differently from the scope of the present invention, the void ratios in wound state were high, and 7% and 8%, respectively.

TABLE-US-00001 TABLE 1 The minimum The maximum Diameter thickness of the thickness of the Difference of converted to R/L ratio of the coating Ds on coating Dm on the thicknesses the round wire hexagonal the flat part the corner part D (mm Φ) cross section (μm) (μm) (μm) Void ratio Example of the Insulated 1.0 1/3 5 6 1 2% present electric wire A invention Insulated 1.0 1/3 10 12 2 2% electric wire B Insulated 1.0  1/10 10 12 2 3% electric wire C Insulated 1.0  1/20 10 12 2 4% electric wire D Insulated 3.0 1/3 40 42 2 3% electric wire E Insulated 3.0  1/10 40 43 3 2% electric wire F Insulated 3.0  1/20 40 43 3 4% electric wire G Insulated 5.0 1/3 100 104 4 4% electric wire H Insulated 5.0  1/10 100 105 5 4% electric wire I Insulated 5.0  1/20 100 105 5 5% electric wire J Comparative Insulated 1.0 (No chamfered 10 18 8 7% Example electric wire X part) Insulated 1.0 (Round cross 10 — — 9% electric wire Y section) Insulated 3.0 (No chamfered 40 55 15 9% electric wire part) Z1 Insulated 5.0 (No chamfered 100 126 26 12%  electric wire part) Z2 Insulated 3.0 1/2 40 42 2 7% electric wire Z3 Insulated 3.0  1/30 40 48 8 8% electric wire Z4 Note: R/L ratio is the ratio of the length R of the chamfered part to the length L of the flat part. D is the difference between the minimum thickness Ds of the insulating coating on the flat part and the maximum thickness Dm of the insulating coating on the corner part.

INDUSTRIAL APPLICABILITY

[0063] An insulated electric wire, which has high degree of freedom in the winding direction and an extremely low void ratio in the wound state, is provided. The insulated electric wire can be utilized more suitably as a wire material for coils such as motors and the like.

REFERENCE SIGNS LIST

[0064] 10: Insulated electric wire [0065] 11: Wire [0066] 12: Insulating coating [0067] 13: Chamfered part [0068] 14: Void [0069] L: Length of the flat part on each side of the hexagonal shape [0070] R: Length of the chamfered part [0071] a, b: End [0072] s: Surface of the entire void formed on the abutted parts of each of the sides A, B, and C of the hexagonal cross section [0073] S: Area surrounded by the entire outline shape including the insulating coating