JP2024083921A - Insulated wire, electric/electronic apparatus, manufacturing method of insulated wire, and manufacturing method of electric/electronic apparatus - Google Patents

Abstract

To provide an insulated wire capable of sufficiently improving adhesiveness of a conductor exposed part and an insulation coating layer when ends are welded to each other and next the insulation coating layer is provided in a periphery of the conductor exposed part, the insulated wire including the ends in which a conductor is exposed by substantially removing only an end coating, and a manufacturing method of the insulated wire.SOLUTION: An insulated wire 1 comprises a conductor 10 and an insulation coating A covering a periphery of the conductor 10. The insulated wire 1 includes an end 11 in which the conductor 10 is exposed. A value (S2/S1) of a ratio of a conductor cross-sectional area (S2) of the end 11 where the conductor 10 is exposed with respect to a conductor cross-sectional area (S1) other than the end 11 where the conductor 10 is exposed is 0.95 or more, and an arithmetic average height Sa of a conductor surface in the end 11 where the conductor 10 is exposed ranges from 1.0 to 5.0 μm. The present invention relates to the insulated wire 1, a manufacturing method of the insulated wire 1, an electric/electronic apparatus using the insulated wire 1, and a manufacturing method of the electric/electronic apparatus.SELECTED DRAWING: Figure 1

Description

The present invention relates to an insulated electric wire, an electric/electronic device, a method for manufacturing an insulated electric wire, and a method for manufacturing an electric/electronic device.

Insulated electric wires have been used for electrical and electronic devices. For example, insulated electric wires are known in which a single or multiple enamel layers are formed around a conductor by applying and baking a varnish containing polyamideimide, polyimide, heat-resistant polyester, polyesterimide, or the like to the conductor. Insulated electric wires are also known in which an insulating coating is formed by extrusion coating a thermoplastic resin around the conductor. Insulated electric wires are also known in which an enamel layer is formed around the conductor, and then an insulating coating consisting of an enamel layer and an extrusion coating layer is formed around the enamel layer by extrusion coating the enamel layer with a thermoplastic resin.
In electric and electronic devices such as motors and transformers, for example, an insulated wire is processed into a hairpin shape to form a segment coil, and the segment coil is pushed into a slot in a stator core, and the ends of the segment coil (insulated wire) protruding from the stator core are welded together to electrically connect them. An insulating coating treatment such as powder coating or varnish coating is applied around the welded part that is electrically connected by welding to form an insulating coating layer. In order to perform this welding, it is necessary to remove the insulating coating (end coating) covering the end of the segment coil to expose the conductor at the end. A method of removing this end coating by mechanical cutting and removal using press processing or the like is known. However, this cutting and removal method has the problem that not only the insulating coating but also the conductor surface layer is largely removed, resulting in a reduction in the cross-sectional area of the conductor. In addition, problems arise in terms of manufacturing efficiency, such as the need to dispose of the shavings of the metal conductor and wear on the mold used in the press processing.
Instead of mechanically removing the end coating, a technique has been proposed in which the end coating is burned off and removed using a laser beam. For example, Patent Document 1 describes that, in manufacturing a rotating electric machine in which an insulated electric wire is wound around an insulated armature, the insulating coating of the insulated electric wire contains transition metal oxide particles that absorb laser beams and generate heat, so that the insulating coating of the end portion of the insulated electric wire can be easily removed by irradiating the insulated electric wire with a laser beam.

JP 2010-15907 A

As described above, after welding the exposed conductors of the ends of the segment coils protruding from the stator core, an insulating coating layer is formed on the exposed conductor portions (exposed conductor portions) by insulating paint. As a result of the inventors' investigation into the adhesion between the exposed conductor portions and the insulating coating layer, it was found that, while it is possible to essentially remove only the end coating without scraping off the conductor when the end coating is removed using laser light, there are limitations to improving the adhesion between the exposed conductor portions and the insulating coating layer. If the adhesion between the exposed conductor portions and the insulating coating layer is insufficient, electricity may flow between the electric wires or between the electric wires and surrounding components, causing problems such as motor damage.

An object of the present invention is to provide an insulated electric wire having an end where substantially only the end coating is removed to expose the conductor, and which, when the ends are welded together and an insulating coating layer is then provided around the exposed conductor portion, can sufficiently enhance adhesion between the exposed conductor portion and the insulating coating layer, and a method for manufacturing the insulated electric wire. Another object of the present invention is to provide an electric/electronic device using the insulated electric wire, and a method for manufacturing the electric/electronic device.
In addition, the above phrase "substantially only the end coating is removed" means that the ratio (S2/S1) of the conductor cross-sectional area (S2) of the end to the conductor cross-sectional area (S1) of the portion other than the end where the conductor is exposed is 0.95 or more.

The inventors of the present invention have conducted extensive research in light of the above problems. As a result, they have found that when the end of an insulated electric wire is irradiated with laser light to essentially remove only the end coating, thereby exposing the conductor at the end of the insulated electric wire, the conductor surface below the end coating can also be unevenly and finely scraped away by the laser light irradiation, and that this allows the conductor surface at the end to be controlled to a specific arithmetic mean height. Furthermore, by controlling the arithmetic mean height of the conductor surface at the end, when the ends with exposed conductors are welded together and an insulating coating layer is formed around the exposed conductor portion, the adhesion between the exposed conductor portion and the insulating coating layer can be effectively improved by controlling the arithmetic mean height of the conductor surface at the end. The present invention was completed based on this knowledge and through further research.

The above object of the present invention can be achieved by the following means.
[1]
An insulated wire having a conductor and an insulating coating covering the conductor,
The insulated wire has an end portion at which a conductor is exposed,
a ratio (S2/S1) of a conductor cross-sectional area (S2) of the end portion where the conductor is exposed to a conductor cross-sectional area (S1) other than the end portion where the conductor is exposed is 0.95 or more;
The insulated wire has an arithmetic mean height Sa of the conductor surface at the end where the conductor is exposed, of 1.0 to 5.0 μm.
[2]
The insulated wire according to [1], wherein an aspect ratio Str of a surface shape of the conductor surface is 0.0 to 0.5.
[3]
The insulated wire according to claim 1 or 2, wherein the end portion at which the conductor is exposed is formed by removing a coating at an end portion of the insulated wire by irradiation with laser light.
[4]
The insulated wire according to any one of [1] to [3], wherein the insulated wire is an insulated wire segmented into a size of 150 to 700 mm in length.
[5]
The insulated wire according to any one of [1] to [4], wherein the insulated wire is a segment coil.
[6]
[1] - [5] An electric/electronic device using the insulated wire according to any one of [1] to [5].
[7]
The electric/electronic device according to [6], wherein the electric/electronic device is a transformer.
[8]
A method for producing an insulated wire includes an end processing step of irradiating an end of an insulated wire having a conductor and an insulating coating covering the conductor with laser light to remove the insulating coating from the end and set the arithmetic mean height Sa of the exposed conductor surface to 1.0 to 5.0 μm.
[9]
The method for producing an insulated wire according to [8], wherein, in the end processing step, the exposed conductor has a surface shape aspect ratio Str of 0.0 to 0.5.
[10]
an end processing step of irradiating the end of the segmented insulated electric wire with a laser beam to remove the insulating coating at the end and set the arithmetic mean height Sa of the surface of the exposed conductor to 1.0 to 5.0 μm;
a coiling process for forming the segmented insulated electric wire that has been subjected to the end processing process into a coil shape to form a segment coil, and then assembling the segment coil into a slot of a stator core;
a welding process for electrically connecting the conductors at the ends of the segment coil by welding them to each other after the assembling process;
a step of insulating coating the exposed conductor portion after the welding step to provide an insulating coating layer around the exposed conductor portion.
[11]
The method for manufacturing an electric/electronic device according to [10], wherein in the end processing step, the aspect ratio Str of a surface shape of the exposed conductor is set to 0.0 to 0.5.

In this invention and this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as the lower and upper limits. For example, when it is written as "A~B", the numerical range is "A or more and B or less".

The insulated wire of the present invention has an end where substantially only the end coating has been removed to expose the conductor, and when the ends are welded together and then an insulating coating layer is provided around the exposed conductor portion, the adhesion between the exposed conductor portion and the insulating coating layer is sufficiently enhanced. Therefore, an electric/electronic device using the insulated wire of the present invention can maintain its performance for a long period of time in the usage environment. Furthermore, according to the manufacturing method of the insulated wire of the present invention, the insulated wire of the present invention can be obtained. Furthermore, according to the manufacturing method of the electric/electronic device of the present invention, the electric/electronic device of the present invention can be obtained.

1 is a cross-sectional view illustrating a schematic configuration example of an insulated wire according to an embodiment of the present invention. 2 is a cross-sectional view taken along line aa in FIG. 1. FIG. 4 is a cross-sectional view illustrating a schematic configuration example of an insulated wire according to another embodiment of the present invention. 1 is a schematic perspective view showing a preferred embodiment of a stator used in an electric/electronic device of the present invention; 1 is a schematic perspective view showing a preferred embodiment of a stator used in an electric/electronic device of the present invention; 1A to 1C are explanatory diagrams illustrating an embodiment of a method for manufacturing an electric/electronic device according to the present invention.

[Insulated wire]
The insulated wire of the present invention has a conductor and an insulating coating covering the periphery of the conductor, the insulated wire has an end portion at which the conductor is exposed, a ratio (S2/S1) of a conductor cross-sectional area (S2) of the end portion at which the conductor is exposed to a conductor cross-sectional area (S1) other than the end portion at which the conductor is exposed is 0.95 or more, and an arithmetic mean height Sa of a conductor surface of the end portion at which the conductor is exposed is 1.0 to 5.0 μm.

Below, a preferred embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, except as specified in the present invention. In addition, the explanation with reference to the drawings below is not limited to the form shown in the drawings, but is applied as an explanation of the configuration of the present invention or the matters specific to the invention.

Figure 1 is a cross-sectional view showing a schematic configuration example of an insulated electric wire 1 according to one embodiment of the present invention, and Figure 2 is a cross-sectional view of line a-a in Figure 1. The insulated electric wire 1 is an insulated electric wire that has been segmented (shortened) to a predetermined size. The length L1 in the longitudinal direction of the insulated electric wire 1 can be, for example, 150 to 700 mm. The X-axis, Y-axis, and Z-axis shown in Figure 1 are three mutually orthogonal axes, and are common to all figures in this specification. The X-axis is an axis parallel to the longitudinal direction of the insulated electric wire 1, and the Y-axis is an axis parallel to the transverse direction of the insulated electric wire 1. The Z-axis is an axis parallel to the thickness direction of the insulated electric wire 1 (the transverse direction perpendicular to the Y-axis).

As shown in FIG. 1, the insulated wire 1 has a rectangular conductor 10, an insulating coating A, and an end portion 11. The insulating coating A is in contact with the conductor 10 and covers the periphery of the conductor 10. The insulating coating A may have a single layer structure or a multi-layer structure. The insulated wire 1 of this embodiment will be described below, starting with the conductor 10.

The conductor 10 can be a wide variety of conductors commonly used in insulated wires, and is usually a metal conductor. The metal conductor preferably contains copper or aluminum, and a copper wire or an aluminum wire is preferably used. When the conductor 10 is a copper wire, the material is, for example, low-oxygen copper, tough pitch copper, or oxygen-free copper. When the conductor 10 is an aluminum wire, the material is, for example, A1070.
In order to suppress partial discharge from the corners, the rectangular conductor 10 is preferably shaped with R-chamfered corners (with a radius of curvature r) as shown in Fig. 2. The radius of curvature r is preferably 0.6 mm or less, and more preferably 0.2 to 0.4 mm.
The size of the conductor 10 is not particularly limited. In the case of a rectangular conductor, the width (long side) of the rectangular cross-sectional shape is preferably 1 to 5 mm, more preferably 1.4 to 4.0 mm, and the thickness (short side) is preferably 0.4 to 3.0 mm, more preferably 0.5 to 2.5 mm. The aspect ratio (D2/D1) of the width (D2) to the thickness (D1) of the conductor 10 is preferably 2 to 5.

The insulating film A may be an enamel layer formed by applying a resin varnish containing an insulating resin (insulating polymer) onto the conductor 10 and baking it, or an extrusion coating layer formed by extruding a thermoplastic resin, or a layer formed by combining these. When the insulating film A includes an enamel layer, the enamel layer may be formed using a thermosetting resin or a thermoplastic resin, and an enamel layer formed by curing a thermosetting resin is preferable. Examples of resins used to form the enamel layer include thermosetting resins having imide bonds such as polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), and polyesterimide (PEsI), polyurethane (PU), thermosetting polyester (PEst), H-type polyester (HPE), polyimide hydantoin-modified polyester, polyhydantoin, polybenzimidazole, melamine resin, and epoxy resin, and one or more of these may be used.

When the insulating coating A includes an extruded coating layer, the thermoplastic resin that is the material for forming the extruded coating layer can be any thermoplastic resin that is commonly used as an insulating resin layer for an insulated electric wire. For example, general-purpose engineering plastics such as polyamide (PA) (nylon), polyacetal (POM), polycarbonate (PC), polyphenylene ether (including modified polyphenylene ether), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and ultra-high molecular weight polyethylene, as well as polysulfone (PSF), polyethersulfone (PES), polyphenylene sulfide (PPS), polyarylate (U-polymer), polyetherketone (PEK), polyaryletherketone (PAEK), tetrafluoroethylene-ethylene copolymer (ETFE), polyetheretherketone (PEEK) (modified polyetheretherketone (modified Examples of the resin include super engineering plastics such as tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), polytetrafluoroethylene (PTFE), thermoplastic polyimide resin (TPI), polyamideimide (PAI), and liquid crystal polyester, as well as polymer alloys based on polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), and polymer alloys including the above engineering plastics such as ABS/polycarbonate, nylon 6,6, aromatic polyamide resin (aromatic PA), polyphenylene ether/nylon 6,6, polyphenylene ether/polystyrene, and polybutylene terephthalate/polycarbonate. These resins may be used alone or in combination of two or more. The thermoplastic resin preferably includes at least one of polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyethylene terephthalate (PET), and nylon 6,6 (nylon 66, PA66).

The thickness of the insulating film A is preferably 200 μm or less, and more preferably 180 μm or less. The thickness of the insulating film A is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. The preferred range for the thickness of the insulating film A is 10 to 200 μm, more preferably 20 to 200 μm, and even more preferably 30 to 180 μm.

The end 11 is a conductor 10 that protrudes from the insulating coating A in the longitudinal direction of the insulated wire 1, and is formed by removing the insulating coating A to expose the conductor 10. The longitudinal dimension L2 of the end 11 is preferably 1 to 50 mm, more preferably 1 to 20 mm, and even more preferably 1 to 15 mm.

The ratio (S2/S1) of the conductor cross-sectional area (S2) of the end 11 where the conductor 10 is exposed to the conductor cross-sectional area (S1) of the portion 12 of the conductor 10 covered with the insulating coating A is 0.95 or more (Regulation 1), preferably 0.96 to 1.00, more preferably 0.97 to 1.00, and even more preferably 0.98 to 1.00. It is also preferable that S2/S1 is 0.99 or less. Note that the above "conductor cross-sectional area" is the cross-sectional area along a plane perpendicular to the longitudinal direction of the insulated electric wire 1 and parallel to the lateral direction. In other words, it is the cross-sectional area of the conductor 10 when viewed in the longitudinal direction of the insulated electric wire 1.

The surface of the end portion 11 (the peripheral surface around the X-axis of the end portion 11) is processed to a predetermined surface roughness after the insulating coating A is removed. The arithmetic mean height Sa of the surface is 1.0 to 5.0 (Regulation 2), preferably 1.2 to 4.5, and more preferably 1.3 to 4.4.
The arithmetic mean height Sa is a value measured in accordance with JIS B 0601 (2001). The method for measuring the arithmetic mean height Sa will be described in detail in the section [Examples] below.
Furthermore, the aspect ratio Str of the surface shape of the surface of the end portion 11 is preferably 0.0 to 0.5, more preferably 0.1 to 0.5, and even more preferably 0.2 to 0.4. By having the aspect ratio Str of the surface shape within the range of 0.0 to 0.5, it is possible to further suppress the formation of voids (air gaps) in the welded portion after the end portions 11 are welded together. Therefore, it is possible to maintain the electrical reliability and mechanical reliability of the welded portion for a longer period of time.
The aspect ratio Str of the surface shape is a value measured in accordance with the surface shape (surface roughness measurement) of ISO 25178. The aspect ratio Str of the surface shape is the average value of five values obtained by measuring five non-overlapping points (each point having an area of ¹ mm2) on the surface of the end portion 11 at a magnification of 400 times using a laser microscope. The method for measuring the aspect ratio Str of the surface shape will be described in detail in the section [Example] below.

The means for forming the end 11 on the insulated wire 1 is not particularly limited as long as it satisfies the above-mentioned requirements 1 and 2, and typically a method is used in which the insulating coating A is removed by irradiating it with laser light. Laser light irradiation will be described later.

3 is a cross-sectional view that illustrates a configuration example of an insulated wire 2 according to another embodiment of the present invention. The insulated wire 2 has a conductor 20 that has a circular cross section and an insulating coating A that contacts the conductor 20 and covers the outer peripheral surface of the conductor 20.
The diameter of the conductor 20 is preferably 0.3 to 3.0 mm, and more preferably 0.4 to 2.7 mm.
The conductor 20 is the same as the conductor 10 described in Figures 1 and 2 except that the cross-sectional shape is circular, and the preferred embodiment is also the same. The insulating coating A of the insulated wire 2 is the same as the insulating coating A described in Figures 1 and 2 except that the insulating coating A covers the conductor 20 having a circular cross-sectional shape, and the preferred embodiment is also the same.

[Method of manufacturing insulated wire]
The method for producing an insulated wire of the present invention preferably includes an end processing step of irradiating an end of an insulated wire having a conductor and an insulating coating covering the periphery of the conductor with laser light to remove the insulating coating at the end and set the arithmetic mean height Sa of the exposed conductor surface to 1.0 to 5.0 μm.

In the end processing step, the insulating coating on the end of the insulated electric wire is removed by laser light irradiation to expose the conductor, and the arithmetic mean height Sa of the exposed conductor surface is controlled to 1.0 to 5.0 μm by this laser light irradiation or by another method. Other methods include sandblasting and pressing, but it is preferable from the viewpoint of manufacturing efficiency to use the laser light irradiation used for removing the insulating coating as it is for controlling the arithmetic mean height Sa of the conductor surface.
In addition, it is preferable to control the aspect ratio Str of the surface shape of the exposed conductor surface to 0.0 to 0.5. The aspect ratio Str of the surface shape can be controlled by laser light irradiation or by the other methods described above. In particular, it is preferable to use laser light irradiation as it is to control the aspect ratio Str of the surface shape. For example, by scanning and irradiating the laser light in a certain direction, it is possible to impart a desired anisotropy to the surface shape of the exposed end conductor, and as a result, it is possible to control the aspect ratio Str of the surface shape to a desired range. Specific methods for these are described in the section [Examples] below.
The method of laser light irradiation for removing the insulating film is itself widely known in the technical field of insulated electric wires. The arithmetic mean height Sa of the conductor surface and the aspect ratio Str of the surface shape due to laser light irradiation can be controlled, for example, by controlling the irradiation conditions of the laser light irradiation (e.g., the frequency, wavelength, and output of the laser, or by controlling the irradiation angle and scanning conditions.

The insulated electric wire subjected to the end processing step may have a length of, for example, 150 to 700 mm. In other words, it is preferable that the insulated electric wire is segmented (shortened). By using a segmented insulated electric wire, it is possible to obtain an insulated electric wire suitable for forming a segment coil.
In the method for producing an insulated electric wire of the present invention, if the insulated electric wire having a conductor and an insulating coating covering the conductor is not segmented, it is preferable to segment (shorten) the insulated electric wire as described above before the end processing step, thereby making it possible to obtain an insulated electric wire of a length suitable for a segment coil.

[Uses of insulated wire]
The insulated wire of the present invention can be preferably coiled into a segment coil and used in fields requiring voltage resistance and heat resistance, such as various electric and electronic devices. That is, the insulated wire of the present invention may be in the form of a segment coil. The electric and electronic devices using this coil are not particularly limited. A preferred embodiment of such an electric and electronic device is a transformer. Another example is a rotating electric machine (e.g., a drive motor for a hybrid vehicle or an electric vehicle) equipped with a stator 30 shown in FIG. 4. This rotating electric machine can have the same configuration as a normal rotating electric machine, except that it is equipped with the stator 30.
The stator 30 can be configured in the same manner as a normal stator, except that the segment coil 1, which is one aspect of the insulated wire of the present invention, is used. That is, the stator 30 has a stator core 31 and a coil 33 in which the segment coil 1 is incorporated into the slot 32 of the stator core 31 and the end 11 is electrically connected, as shown in FIG. 5. Here, the segment coil 1 may be incorporated into the slot 32 by itself, but is preferably incorporated as a set of two coils as shown in FIG. 5. In this stator 30, the coil 33 is formed by connecting the two ends 11 of the segment coil 1 bent as described above in a stator core 31 slot. At this time, the end 11 of the segment coil 1 may be connected before being stored in the slot 32, or the end 11 of the segment coil 1 may be bent and then connected after the segment coil 1 is stored in the slot 32.

[Manufacturing methods for electrical and electronic equipment]
The method for producing an electric/electronic device of the present invention preferably includes the following steps.

an end processing step of irradiating the end of the segmented insulated electric wire with a laser beam to remove the insulating coating at the end and set the arithmetic mean height Sa of the surface of the exposed conductor to 1.0 to 5.0 μm;
a coiling process for forming the segmented insulated electric wire that has been subjected to the end processing process into a coil shape to form a segment coil, and then assembling the segment coil into a slot of a stator core;
After the assembly process, a welding process is performed in which the conductors at the ends of the segment coil are welded together to electrically connect them, and after the welding process, an insulating coating process is performed in which an insulating coating layer is provided around the exposed conductor portion by applying an insulating coating to the exposed conductor portion.

The length of the segmented insulated wire may be, for example, 150 to 700 mm, as explained above.
The end processing step is the same as the end processing step explained in the method for producing an insulated electric wire of the present invention.
The above-mentioned assembly process and insulating coating process are known processes, and ordinary methods can be appropriately applied.

A preferred embodiment of the method for manufacturing an electric/electronic device will now be described in more detail with reference to the drawings.
6 is an explanatory diagram that shows an embodiment of the method for manufacturing an electric/electronic device of the present invention, taking the manufacture of a rotating electric machine as an example. Note that the method for manufacturing an electric/electronic device of the present invention is not limited to the following embodiment except as specified in the present invention.

Figure 6 shows the process of shortening the long wound insulated wire (segmentation process). The insulated wire of a given length obtained by the shortening process is subjected to the end processing process, and then goes through the assembly process, welding process, and insulating coating process to manufacture the rotating electric machine. Each of these processes will be explained below.

<Shortening process>
In the shortening step, the insulated wire wound around the roller R is cut at predetermined intervals, thereby obtaining an insulated wire shortened to the desired length described above.

<End processing process>
In the end processing step, the insulating coating at the end of the shortened insulated electric wire is burned (pyrolyzed) and removed by irradiation with laser light, exposing the conductor 10 at the end. At the same time, this laser light irradiation processes the surface of the exposed conductor 10 into a state that satisfies the above-mentioned specifications 1 and 2 (if necessary, into a state in which the aspect ratio Str of the surface shape of the end 11 satisfies 0.0 to 0.5). In this way, the insulated electric wire 1 is obtained.

The scanning trajectory of the laser light irradiation may be, for example, long and parallel, or may be quincunx, and is preferably long and parallel. A "long and parallel scanning trajectory" means that a plurality of grooves extending in the longitudinal direction of the insulated electric wire 1 are formed on the surface of the end portion 11 at a predetermined pitch in the lateral direction. A "quincunx scanning trajectory" means that a plurality of grooves extending in the longitudinal direction of the insulated electric wire 1 are formed on the surface of the end portion 11 at a predetermined pitch in the lateral direction, and further, a plurality of grooves extending in the lateral direction of the insulated electric wire 1 are formed at a predetermined pitch in the longitudinal direction. The pitch is preferably 20 to 30 μm.

Examples of the laser used for the laser light irradiation include a fiber laser, a _CO2 laser, and a YAG laser, and the laser may be a continuous wave (CW) or pulsed laser. Methods for removing an insulating coating by laser light irradiation are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 6-38330, 2001-309521, and 2005-285755.
Specific examples of the conditions for the laser light irradiation of the present invention will be described in the section [Examples] below.

<Assembly process>
In the assembly process, the insulated wire 1, from whose end the insulating coating has been removed, is bent into a hairpin shape to produce the segment coil 1. Next, the segment coil 1 is inserted into the slot 32 of the stator core 31, and the segment coil 1 protruding from the surface of the stator core 31 is twisted.

<Welding process>
In the welding process, the end 11 of one segment coil 1 and the end 11 of the other segment coil 1 are welded to electrically connect them. Examples of the welding method include arc welding, laser welding, electron beam welding, and resistance welding. In this welding process, the conductor portion that forms the surface to be insulated is welded so as to substantially maintain the surface state (arithmetic mean height Sa and aspect ratio Str of the surface shape) formed in the end processing process.

<Insulation coating process>
After the above welding process, the exposed conductor portion is, for example, subjected to an insulating powder coating, and the exposed conductor portion is coated with an insulating material to form the insulating coating layer 34. In this embodiment, the segment coil 1 satisfies the above-mentioned regulations 1 and 2, so that the adhesion between the exposed conductor portion and the insulating coating layer 34 is sufficiently enhanced.

Through each of the above steps, the desired electrical and electronic devices can be obtained.

The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[Preparation of insulated wire]
Example 1
In Example 1, an insulated wire 1 (before end processing, the same applies below) shown in Figs. 1 and 2 was produced.
The conductor 10 was made of a copper wire (material: oxygen-free copper, cross-sectional shape: rectangular, cross-sectional area: 3 mm ² , aspect ratio: 5).
The insulating coating A was formed using a die similar in shape to the insulating coating A formed on the conductor 10. A thermosetting resin varnish (manufactured by Unitika Ltd., product name: U-imide, resin type: polyimide) was coated onto the conductor 10 using the die, and the conductor 10 was passed through a hot air circulating furnace with a length of 8 m and an internal temperature of 400 to 650° C. at a speed that gave a passing time of 10 to 90 seconds. This process was repeated 16 to 35 times to form an insulating coating A (enamel layer) with a thickness of 50 μm.

Example 2
In Example 2, an insulated wire 2 shown in FIG. 3 was produced.
The conductor 20 was made of a copper wire (material: oxygen-free copper, cross-sectional shape: circular, cross-sectional area: 3 mm ² ).
In forming the insulating coating A, an extruder screw with a full flight of 30 mm, L/D = 25, and a compression ratio of 3 was used. Thermoplastic resin (manufactured by Victrex Japan, product name: 450G, resin type: PEEK) was used, and extrusion coating was performed using an extrusion die at 390°C (extrusion die temperature) so that the outer shape of the cross section of the insulating coating A was similar to the shape of the conductor 20, forming an insulating coating A (extrusion coating layer) with a thickness of 50 µm.

Example 3
In Example 3, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 10 was made of a copper wire (material: oxygen-free copper, cross-sectional shape: rectangular, cross-sectional area: 6 mm ² , aspect ratio: 2).
The insulating film A was formed in the same manner as in Example 1, and an insulating film A (enamel layer) having a thickness of 100 μm was formed.

Example 4
In Example 4, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 10 was made of a copper wire (material: oxygen-free copper, cross-sectional shape: rectangular, cross-sectional area: 6 mm ² , aspect ratio: 5).
The insulating film A was formed in the same manner as in Example 2, and an insulating film A (extruded coating layer) having a thickness of 100 μm was formed.

Example 5
In Example 5, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 10 was made of a copper wire (material: oxygen-free copper, cross-sectional shape: rectangular, cross-sectional area: 9 mm ² , aspect ratio: 5).
The insulating film A was formed in the same manner as in Example 1, and an insulating film A (enamel layer) having a thickness of 170 μm was formed.

Example 6
In Example 6, the insulated wire 2 shown in FIG. 3 was produced.
The conductor 20 was made of a copper wire (material: oxygen-free copper, cross-sectional shape: circular, cross-sectional area: 9 mm ² ).
The insulating film A was formed in the same manner as in Example 1, and an insulating film A (enamel layer) having a thickness of 170 μm was formed.

Example 7
In Example 7, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 10 was made of a copper wire (material: tough pitch copper, cross-sectional shape: rectangular, cross-sectional area: 3 mm ² , aspect ratio: 5).
In forming the insulating film A, an insulating film A (enamel layer) having a thickness of 50 μm was formed in the same manner as in Example 1.

Example 8
In Example 8, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 10 was made of a copper wire (material: tough pitch copper, cross-sectional shape: rectangular, cross-sectional area: 6 mm ² , aspect ratio: 2).
The insulating film A was formed in the same manner as in Example 1, and an insulating film A (enamel layer) having a thickness of 100 μm was formed.

<Example 9>
In Example 9, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 20 was made of a copper wire (material: tough pitch copper, cross-sectional shape: rectangular, cross-sectional area: 6 mm ² , aspect ratio: 5).
In forming the insulating coating A, an enamel layer having a thickness of 50 μm was formed in the same manner as in Example 1, and then an extrusion coating layer having a thickness of 120 μm was formed on the outside of the enamel layer in the same manner as in Example 2. In Example 9, the thickness of the insulating coating A was 170 μm.

Example 10
In Example 10, the insulated wire 1 shown in Figs. 1 and 2 was produced.
For the conductor 10, an aluminum wire (material: A1070, cross-sectional shape: rectangular, cross-sectional area: 3 mm ² , aspect ratio: 5) was used.
In forming the insulating film A, an insulating film A (extruded coating layer) having a thickness of 50 μm was formed in the same manner as in Example 2.

Example 11
In Example 11, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 10 was made of an aluminum wire (material: A1070, cross-sectional shape: rectangular, cross-sectional area: 6 mm ² , aspect ratio: 2).
The insulating film A was formed in the same manner as in Example 2, and an insulating film A (extruded coating layer) having a thickness of 100 μm was formed.

<Comparative Example 1>
In Comparative Example 1, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 10 was made of a copper wire (material: oxygen-free copper, cross-sectional shape: rectangular, cross-sectional area: 6 mm ² , aspect ratio: 2).
The insulating film A was formed in the same manner as in Example 1, and an insulating film A (enamel layer) having a thickness of 100 μm was formed.

<Comparative Example 2>
In Comparative Example 2, an insulated wire 2 shown in FIG. 3 was produced.
The conductor 20 was made of a copper wire (material: tough pitch copper, cross-sectional shape: circular, cross-sectional area: 6 mm ² ).
The insulating film A was formed in the same manner as in Example 2, and an insulating film A (extruded coating layer) having a thickness of 100 μm was formed.

<Comparative Example 3>
In Comparative Example 3, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 10 was made of a copper wire (material: oxygen-free copper, cross-sectional shape: rectangular, cross-sectional area: 6 mm ² , aspect ratio: 2).
The insulating film A was formed in the same manner as in Example 1, and an insulating film A (enamel layer) having a thickness of 100 μm was formed.

<Comparative Example 4>
In Comparative Example 4, the insulated wire 1 shown in Figs. 1 and 2 was produced.
The conductor 10 was made of a copper wire (material: oxygen-free copper, cross-sectional shape: rectangular, cross-sectional area: 6 mm ² , aspect ratio: 5).
The insulating film A was formed in the same manner as in Example 2, and an insulating film A (extruded coating layer) having a thickness of 100 μm was formed.

[Laser peeling test (edge processing)]
The insulated wires according to the examples and comparative examples were cut into segments each having a length of 500 mm, and the insulating coating covering one end of each segment was removed by irradiating the segment with a laser beam, while the exposed conductor surface was finely scraped off by the laser beam irradiation to control the surface roughness. The conditions for irradiating the laser beam were as shown in Table 1 below. CW stands for continuous wave. In each of the examples and comparative examples, the ratio (S2/S1) of the conductor cross-sectional area (S2) of the end where the conductor was exposed to the conductor cross-sectional area (S1) of the other end where the conductor was exposed was within the range of 0.95 to 1.00.

[Surface roughness measurement]
Next, in the segments of the insulated electric wires according to the examples and the comparative examples in which the laser peeling test was performed, the arithmetic mean height Sa of the conductor surface exposed by the laser light irradiation and the aspect ratio Str of the surface shape were measured. Specifically, the arithmetic mean height Sa and the aspect ratio Str of the surface shape were determined as the average value of five values obtained by measuring five different regions (area of each region: 1 mm ² ) of the conductor surface exposed by the laser light irradiation at a magnification of 400 times using a laser microscope (manufactured by Keyence Corporation, product name: VK-X250). When impregnated varnish or the like was attached to the electric wire, it was dissolved and removed with a chemical such as an insulating coating remover (manufactured by Meiwa Chemical Industry Co., Ltd., product name: Solcoat) before measuring the surface roughness. In addition, when a powder coating was attached, the powder coating was mechanically peeled off and removed because it is a brittle material. The measurement results of the arithmetic mean height Sa are shown in Table 2, and the measurement results of the aspect ratio Str of the surface shape are shown in Table 3.

[Shear strength test]
Two segments of the insulated electric wire according to the examples and comparative examples on which the laser peeling test was performed were prepared, and the two segments were arranged in parallel with the exposed end conductors arranged side by side (simulating the welding in FIG. 6), and the exposed end conductors were welded together by a fiber laser. Next, the exposed conductor portion was immersed at high temperature in a powder bath containing a mixed powder of epoxy resin and filler to apply an insulating powder coating to form an insulating coating layer. The shear strength of the insulating coating layer corresponding to the laser light scanning surface in the laser peeling test (the adhesion force between the insulating coating layer and the portion where the insulating film was peeled off for welding, N/mm ² ) was measured using a sample cut to a size of 1 mm in diameter, and evaluated according to the following criteria. The results are shown in Table 2.
(Shear strength test criteria)
◎: Shear strength is 1.0 N/mm2 ^or more. ◯: Shear strength is 0.7 N/ ^mm2 or more and less than 1.0 N/ ^mm2. △: Shear strength is 0.5 N/ ^mm2 or more and less than 0.7 N/ ^mm2. ×: Shear strength is less than 0.5 N/ ^mm2.

As shown in Table 2, the insulated wires according to Comparative Examples 1 to 4 had poor paint adhesion (adhesion between the insulating coating layer and the portion where the insulating film has been peeled off for welding). In contrast, the insulated wires according to Examples 1 to 11 were found to have excellent paint adhesion.

[Void area ratio measurement]
For the welded portion on which the insulating coating layer was formed by the powder coating, a cross section along the short direction of the electric wire (a cross section along a direction perpendicular to the longitudinal direction of the electric wire) was wet-polished and then observed to determine the void area ratio (%) in the observation field. Specifically, the wet-polished welded portion cross section was photographed at a magnification of 50 times using an optical microscope, and the obtained image was binarized using image processing software (ImageJ), and then the ratio of the void area (E2) to the conductor area (E1) in the image ((E2/E1) x 100) was calculated. In the same manner, the ratio of E2 to E1 was calculated for a total of three welded portion cross sections. The average value of the calculated values (three calculated values) for the three cross sections was taken as the void area ratio (%). The results are shown in Table 3.

As shown in Table 3, the insulated wires according to Comparative Examples 1 and 2, in which the aspect ratio Str of the surface shape was in the range of 0.0 to 0.5, suppressed the generation of voids in the welded portion. However, the insulated wires according to Comparative Examples 3 and 4, in which the aspect ratio Str of the surface shape was greater than 0.5, generated more voids in the welded portion than in Comparative Examples 1 and 2.
Similarly, it was confirmed that in the insulated wires of Examples 1 to 11, in which the aspect ratio Str of the surface shape is within the range of 0.0 to 0.5, the generation of voids in the welded portion is significantly suppressed compared to the insulated wires of Comparative Examples 3 and 4.
From the above results, it was found that when the aspect ratio Str of the surface shape is within the range of 0.0 to 0.5, the generation of voids in the welded portion is effectively suppressed.

1,2...insulated wire, 10,20...conductor, 11...end, 34...insulating coating layer, A...insulating film.

Claims (11)

An insulated wire having a conductor and an insulating coating covering the conductor,
The insulated wire has an end portion at which a conductor is exposed,
a ratio (S2/S1) of a conductor cross-sectional area (S2) of the end portion where the conductor is exposed to a conductor cross-sectional area (S1) other than the end portion where the conductor is exposed is 0.95 or more;
The insulated wire has an arithmetic mean height Sa of the conductor surface at the end where the conductor is exposed, of 1.0 to 5.0 μm. The insulated wire according to claim 1, wherein the aspect ratio Str of the surface shape of the conductor surface is 0.0 to 0.5. The insulated wire according to claim 2, wherein the end where the conductor is exposed is formed by removing the coating at the end of the insulated wire by irradiating it with laser light. The insulated wire according to claim 3, wherein the insulated wire is segmented to a length of 150 to 700 mm. The insulated wire according to claim 4, wherein the insulated wire is a segment coil. An electric/electronic device using the insulated wire according to any one of claims 1 to 5. The electric/electronic device according to claim 6, wherein the electric/electronic device is a transformer. A method for manufacturing an insulated electric wire, comprising an end processing step of irradiating the end of an insulated electric wire having a conductor and an insulating coating surrounding the conductor with laser light to remove the insulating coating from the end and set the arithmetic mean height Sa of the exposed conductor surface to 1.0 to 5.0 μm. The method for manufacturing an insulated electric wire according to claim 8, wherein in the end processing step, the aspect ratio Str of the surface shape of the exposed conductor is set to 0.0 to 0.5. an end processing step of removing the insulating coating at the end by irradiating the end of the segmented insulated electric wire with a laser beam and setting the arithmetic mean height Sa of the surface of the exposed conductor to 1.0 to 5.0 μm;
a coiling process for forming the segmented insulated electric wire that has been subjected to the end processing process into a coil shape to form a segment coil, and then assembling the segment coil into a slot of a stator core;
a welding process for electrically connecting the conductors at the ends of the segment coil by welding them to each other after the assembling process;
a step of insulating coating the exposed conductor portion after the welding step to provide an insulating coating layer around the exposed conductor portion. 11. The method for manufacturing an electric/electronic device according to claim 10, wherein in the end processing step, an aspect ratio Str of a surface shape of the exposed conductor is set to 0.0 to 0.5.

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