JP2013038881A - Manufacturing method of rotary electric machine and manufacturing method of connection substrate of rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to downsize a connection substrate of a rotary electric machine.SOLUTION: In a manufacturing method of a rotary electric machine 1 comprising a rotor 3, a stator 2, and a connection substrate 100 which performs connection processing of an end 7a of a winding 7 of the stator 2 with a predetermined connection pattern, the connection substrate 100 is manufactured by a manufacturing method comprising: a step of molding in a spiral shape a coating rectangular wire 101, which is a conductive wire; a step of forming an insulation member 120 by coating at least a part of a surface of the coating rectangular wire 101 which is molded in a spiral shape with an insulation material; and a step of dividing the coating rectangular wire 101 coated with the insulation material at a predetermined circumferential position.

Description

  Embodiments disclosed herein relate to a method of manufacturing a rotating electrical machine and a method of manufacturing a connection board of the rotating electrical machine.

  Patent Document 1 describes a rotating electric machine that performs connection processing on the end of a winding of a stator with a connection board. This connection board is formed into a disk shape by an insulating material, and has an insulating member (connection board) having a plurality of arc-shaped grooves on one end face in the radial direction and an insertion hole communicating with the groove on the other end face; A terminal piece having a U-shaped groove on the side surface of the band-shaped conductor, a band-shaped conductor inserted into the groove of the insulating member, and a conductive member (phase-specific conductive member) protruding from the insertion hole. ing.

JP 2006-158199 A

  The said connection board | substrate has the structure which the terminal piece protruded to the radial direction outer peripheral side from the insulating member. Also, in order to prevent the terminal piece of the conductive member on the inner peripheral side from interfering with the conductive member on the outer peripheral side, the terminal piece is detoured in the axial direction, or the conductive member is shifted in the axial direction for each phase. There is a need. For this reason, the connection board has room for further miniaturization in the radial direction and the axial direction.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a method for manufacturing a rotating electrical machine and a method for manufacturing a wiring board for a rotating electrical machine that can reduce the size of the connection board.

  In order to solve the above-described problem, according to one aspect of the present invention, a rotating electrical machine including a rotor and a stator, and a wiring board that performs wiring processing on an end portion of the winding of the stator with a predetermined wiring pattern. The wiring board is a first step of forming a conductive wire in a spiral shape, and a second step of covering at least a part of the surface of the spirally shaped wire with an insulating material, And a third step of dividing the wire covered with the insulating material at a predetermined circumferential position, and a method of manufacturing a rotating electrical machine manufactured by a manufacturing process is applied.

  According to another aspect of the present invention, there is provided a connection board manufacturing method provided in a rotating electric machine having a rotor and a stator, wherein the end of the stator winding is connected with a predetermined connection pattern. A first step of forming a conductive wire in a spiral shape, a second step of covering at least a part of the surface of the spirally formed wire with an insulating material, and a wire covered with the insulating material as predetermined. And a third step of dividing at a position in the circumferential direction of the rotating electrical machine.

  According to the method for manufacturing a rotating electrical machine of the present invention, the connection board can be reduced in size.

It is a longitudinal cross-sectional view showing the whole structure of the rotary electric machine of embodiment. It is the top view seen from the axial direction anti-load side showing the whole structure of a connection board | substrate. It is sectional drawing of the connection board | substrate by the III-III cross section in FIG. It is the top view seen from the axial direction load side showing the whole structure of a connection board | substrate. It is explanatory drawing for demonstrating the connection pattern by a connection board | substrate. It is a connection diagram of the rotating electrical machine of the embodiment. It is a figure showing the state which shape | molded the covering flat wire in the shape of a spiral. It is a figure showing the state which coat | covered the spiral covering flat wire with the insulating material. It is a figure showing the state which cut | disconnected the covering rectangular wire in the predetermined position. It is a figure showing the state which provided the through-hole in the divided | segmented covering flat wire. It is a figure showing the state which pulled out the edge part of the coil | winding from the stator. It is a figure showing the state which penetrated the coil | winding edge part of the stator through the through-hole of the corresponding electrically-conductive member. It is a figure showing the state which fixed the connection board | substrate to the stator and cut | disconnected the excess part of the coil | winding edge part. It is a figure showing the state which fixed the coil | winding edge part to the electrically-conductive member by soldering.

  Hereinafter, an embodiment will be described with reference to the drawings.

<Overall configuration of rotating electrical machine>
First, the whole structure of the rotary electric machine 1 of this embodiment is demonstrated using FIG. As shown in FIG. 1, the rotating electrical machine 1 includes a stator 2 and a rotor 3. The stator 2 is provided on the inner peripheral surface of the frame 4 so as to face the rotor 3 in the radial direction, and the laminated iron core body 5, the bobbin 6 through which the laminated iron core body 5 is inserted, and the bobbin 6 are wound around. And a wound winding 7. The bobbin 6 is made of an insulating material such as a resin in order to electrically insulate the laminated core 5 and the winding 7. On the opposite side of the bobbin 6 (left side in FIG. 1), an annular connection board 100 for connecting the end 7a of the winding 7 with a predetermined connection pattern is provided. The winding end 7 a is fixed to the wiring board 100 with solder H. The wiring board 100 is covered with a resin 15.

  The rotor 3 has a yoke 8 and a permanent magnet 9 and is provided on the outer peripheral surface of the rotating shaft 10. The rotating shaft 10 is rotatably supported by a load-side bearing 12 in which an outer ring is fitted to the load-side bracket 11 and an anti-load-side bearing 14 in which an outer ring is fitted to the anti-load-side bracket 13.

  Below, the case where the rotary electric machine 1 is a three-phase AC motor having a stator 2 in which 12 windings 7 are assembled in an annular shape will be described as an example.

<Configuration of wiring board>
Next, the configuration of the wiring board 100 will be described with reference to FIGS. As shown in FIG. 2, the wiring board 100 includes a plurality of arc-shaped conductive members 110 arranged concentrically connected to the winding end 7 a of the stator 2, and an annular shape covering these conductive members 110. Insulating member 120. As will be described in detail later, the plurality of conductive members 110 are formed by forming a covered rectangular wire 101 (see FIG. 7), which is a single wire, into a spiral shape and dividing (deleting) at a predetermined location. Yes. That is, the conductive member 110 can also be said to be a configuration in which conductive wires divided by the missing portion are arranged in multiple directions in the radial direction. Actually, a defective portion is generated in the insulating member 120 when the coated rectangular wire 101 is divided, but the illustration is omitted in FIG.

  In the example shown in FIG. 2, the conductive members 110 are arranged substantially concentrically so as to be quadruple in the radial direction. The six conductive members 110a to 110f arranged on the innermost side are crossover conductive members, and are arranged at substantially equal intervals along the circumferential direction of the concentric circle R1. The two conductive members 110n and 110n disposed on the outer peripheral side of the conductive members 110a to 110f are conductive members for neutral points, and are disposed along the circumferential direction of the concentric circle R2. The conductive members 110u and 110v arranged on the outer peripheral side of the conductive members 110n and 110n are U-phase and V-phase conductive members, respectively, and are arranged so as to be substantially along the circumferential direction of the concentric circle R3. The conductive member 110w disposed on the outermost periphery side is a W-phase conductive member, and is disposed along the circumferential direction of the concentric circle R4. Hereinafter, the conductive members are appropriately referred to as crossover conductive members 110a to 110f, neutral point conductive members 110n, U-phase conductive members 110u, V-phase conductive members 110v, and W-phase conductive members 110w.

  Most of the U-phase conductive member 110u is arranged along the concentric circle R3, but a part thereof is arranged along the concentric circle R4. Of the U-phase conductive member 110u, a portion along the concentric circle R3 is referred to as an inner peripheral portion 110ui, and a portion along the concentric circle R4 is referred to as an outer peripheral portion 110uo. The U-phase conductive member 110u is concentrically arranged, and is integrally provided between two arc-shaped inner peripheral portions 110ui and outer peripheral portions 110ui having different curvature radii, and is tangent X of the inner peripheral portion 110ui. It has the structure which has the linear part 110uc extended linearly in a direction.

  Similarly, most of the V-phase conductive member 110v is arranged along the concentric circle R3, but a part thereof is arranged along the concentric circle R2. Of the V-phase conductive member 110v, a portion along the concentric circle R2 is referred to as an inner peripheral portion 110vi, and a portion along the concentric circle R3 is referred to as an outer peripheral portion 110vo. The V-phase conductive member 110v is concentrically arranged, and is integrally provided between two arc-shaped inner peripheral portions 110vi and outer peripheral portions 110vo having different curvature radii. The tangent line Y of the inner peripheral portion 110vi is provided. It has the structure which has the linear part 110vc extended linearly in a direction.

  As shown in FIG. 3, the conductive member 110 (covered flat wire 101) has a substantially square cross-sectional shape, and includes a conductive material 111 and a covering material 112 that covers the conductive material 111. As shown in FIGS. 2 and 3, each conductive member 110 has a through-hole 113 that penetrates the winding end 7 a in the rotational axis direction at substantially the center position in the width direction at both ends in the longitudinal direction. The winding end portion 7 a that penetrates the through hole 113 is fixed to the surface of the conductive member 110 on the connection side (the antiload side) with solder H. At this time, the covering material 112 is peeled around the through hole 113 in the conductive member 110, and the solder H is provided at the peeled portion.

  The insulating member 120 is an annular member formed by insert molding of a resin material, for example, and fixes each conductive member 110 at a predetermined position so as to be on the same plane substantially perpendicular to the rotation axis direction. Insulation between the conductive members 110 is ensured. As shown in FIGS. 2 and 3, the insulating member 120 is provided so as to expose at least the connection-side surface of the conductive member 110 and cover the other surface. As shown in FIG. 3, each conductive member 110 is actually arranged so as to have a predetermined gap in the radial direction by the insulating member 120, but this gap is not shown in FIG.

  As shown in FIGS. 3 and 4, the insulating member 120 has a tapered hole 121 at a position corresponding to the through hole 113 of the conductive member 110. The tapered hole 121 is provided on the surface 122 on the anti-connection side (load side) of the insulating member 120 and is formed so that the hole diameter gradually decreases from the surface 122 toward the through hole 113 of the conductive member 110. ing. The winding end portion 7 a of the stator 5 is inserted from the stator 5 side into the through hole 113 of the conductive member 110 through the tapered hole 121.

<Connection pattern>
Next, a connection pattern by the connection substrate 100 will be described with reference to FIGS. 5 and 6. 5 and 6 have a corresponding relationship, and in the description here, for example, the winding 7 corresponding to U1 is referred to as a winding U1.

  As shown in FIGS. 5 and 6, the wiring board 100 is a wiring pattern having two systems of star connections that connect three-phase phases at a neutral point at one end thereof, and connects the winding end 7 a of the stator 2. To do. Specifically, the windings U1 and U2 on one side of the U phase are connected to each other by the crossover conductive member 110c, and the windings that are on the other side of the U phase. The ends 7a on one side of the wire U3 and the winding U4 are connected by a crossover conductive member 110f. Similarly, the ends 7a on one side of the winding V1 and the winding V2 which are systems on one side of the V phase are connected by the crossover conductive member 110e, and the winding V3 which is the system on the other side of the V phase. The ends 7a on one side of the winding V4 are connected by a crossover conductive member 110b. Similarly, the end portions 7a on one side of the winding W1 and the winding W2 which are systems on one side of the W phase are connected by a crossover conductive member 110d, and the winding which is the system on the other side of the W phase. One end portions 7a of W3 and winding W4 are connected to each other by a crossover conductive member 110a.

  The other end portions 7a of the windings U2, V2, and W2 are connected to each other by a neutral point conductive member 110n. Similarly, the other end portions 7a of the windings U4, V4, and W4 are connected to each other. They are connected by a conductive member 110n for sex points. The other end 7a of the winding U1 and the other end 7a of the winding U3 are connected to the U phase via the U phase conductive member 110u, and the other end of the winding V1 is connected. The portion 7a and the other end 7a of the winding V3 are connected to the V phase via the V-phase conductive member 110v, and the other end 7a of the winding W1 and the other end of the winding W3 are connected to the V phase. The end 7a is connected to the W phase via the W phase conductive member 110w.

<Manufacturing method of wiring board and rotating electrical machine>
Next, a method for manufacturing the wiring board 100 and the rotating electrical machine 1 will be described with reference to FIGS. First, as shown in FIG. 7, a single covered rectangular wire 101 is formed into a spiral shape. At this time, a simple spiral shape whose curvature radius continuously changes may be used, but a spiral shape having linear portions 101a to 101c extending linearly in the tangential direction of the arc portion along the concentric circle R on the inner peripheral side is desirable. . By adopting the latter shape, portions other than the straight portions 101a to 101c of the covered rectangular wire 101 can be arranged on the concentric circles R1 to R4. Connection work with 7a can be facilitated. As described above, the covered rectangular wire 101 includes the conductive material 111 and the covering material 112, and has a substantially square cross-sectional shape. Further, the straight portions 101b and 101c shown in FIG. 7 correspond to the straight portions 110vc and 110uc shown in FIG. 2, respectively. In addition, this process is corresponded to the 1st process as described in a claim.

  In the example shown in FIG. 7, the coated rectangular wire 101 is wound so as to be quadruple in the radial direction. However, the number of turns is not limited to this, and an appropriate number of turns is set according to the connection pattern of the connection substrate 100. Set to

  Next, the covered rectangular wire 101 is covered with an insulating material, for example, by fixing the covered rectangular wire 101 formed in a spiral shape to a mold and insert-molding a resin material. At this time, the covering flat wire 101 is covered so that at least the connection side surface is exposed. Thereby, as shown in FIG. 8, the insulating member 120 is formed. In addition, this process is corresponded to the 2nd process as described in a claim.

  Next, as shown in FIG. 9, the coated rectangular wire 101 covered with the insulating material is divided at a predetermined circumferential position so as to have the connection pattern shown in FIG. 5. In the present embodiment, the covering flat rectangular wire 101 has a missing portion S (having a predetermined length so that the connection position with the winding end portion 7a is located at both longitudinal ends of each conductive member 110 formed by dividing. 9 is formed using, for example, a drill or a punch press. As a result, each conductive member 110 formed by dividing has a concave curved surface 114 corresponding to the shape of the drill or punch press at both ends in the circumferential direction. As described above, when the covering rectangular wire 101 is divided, the insulating member 120 also has a defect, but in FIG. 9 (the same applies to FIGS. 10, 12, 13, and 14 described later), the insulating member is used to prevent complication. Illustration of 120 missing portions is omitted. In addition, this process is corresponded to the 3rd process as described in a claim.

  Note that the defect portion S does not necessarily have a predetermined length as in this embodiment, and may be a defect portion S having a short length such as a simple round hole or a square hole. Moreover, you may sever using tools other than a drill and a punch press. Furthermore, the end surface shape of each conductive member 110 may be formed in a flat surface instead of a curved surface. That is, the shape and length of the defect portion S are not limited as long as the covered rectangular wire 101 is divided to such an extent that insulation between the conductive members 110 can be secured.

  Next, as shown in FIG. 10, each conductive member 110 is provided with a through-hole 113 that penetrates the winding end 7 a in the rotation axis direction using a drill or the like. The through hole 113 is provided at a substantially central position in the width direction at both longitudinal ends of each conductive member 110. Further, the covering material 112 around the through hole 113 in each conductive member 110 is peeled off using a sandpaper, a knife or the like. Furthermore, a tapered hole 121 is provided using a drill or the like at a position corresponding to the through hole 113 on the surface 122 on the anti-connection side of the insulating member 120. The wiring board 100 is manufactured through the above steps.

  Next, as shown in FIG. 11, the end 7 a of each winding 7 is pulled out from the stator 2 along the direction of the rotation axis to the anti-load side (the front side of the paper surface in FIG. 11). At this time, two end portions 7a corresponding to the winding start and the winding end of each winding 7 are drawn out.

  Next, as shown in FIG. 12, the winding end portions 7 a drawn out from the stator 2 are passed through the through holes 113 of the corresponding conductive members 110 through the tapered holes 121 provided in the insulating member 120. After that, as shown in FIG. 13, the wiring board 100 is fixed to the insulator (not shown) of the stator 2 with an adhesive or the like, and the winding end 7 a slightly protrudes from the connection-side surface of each conductive member 110. The unnecessary portion is cut so as to be a length. Then, as shown in FIG. 14, soldering is performed to fix each winding end portion 7 a to each conductive member 110 with solder H. As described above, the wiring board 100 is attached to the stator 2, and the rotating electrical machine 1 is manufactured.

  The step of providing the through hole 113 in the conductive member 110 (FIG. 10) and the step of penetrating the winding end 7a through the through hole 113 through the tapered hole 121 (FIG. 12) are within the scope of the claims. This corresponds to the fourth step described. In addition, the manufacturing process described above can be largely automated except for a part that requires manual work such as fixing the covered rectangular wire 101 to the mold when the insulating member 120 is formed.

<Effect of embodiment>
According to the embodiment described above, the following effects can be obtained. That is, as in the present embodiment, by forming the connection substrate 100 by dividing the coated rectangular wire 101, which is a single conductive wire made into a spiral shape, at a predetermined circumferential position, it is formed by dividing. The plurality of conductive members 110 formed can be arranged on the same plane that is substantially perpendicular to the rotation axis direction. Thereby, the axial direction dimension of the wiring board 100 can be made as small as possible. As a result, the rotating electrical machine 1 can be reduced in size. In addition, as a result of forming the conductive member 110 using a single wire in this way, material waste can be greatly suppressed and costs can be reduced compared to the case where the conductive member 110 is formed by punching from a metal member or the like. be able to.

  In this embodiment, in particular, the through hole 113 is provided in the conductive member 110, and the winding end portion 7 a of the stator 2 is passed through the through hole 113 in the rotation axis direction and directly connected to the conductive member 110. This eliminates the need for a terminal member for connecting the winding end portion 7a and the conductive member 110, so that the diameter of the wiring board 100 is smaller than the configuration in which the terminal member is provided to protrude radially outward from the insulating member 120. The direction dimension can be reduced. In addition, when the terminal member is protruded to the outer peripheral side of the insulating member 120, is the terminal member provided in a detour in the axial direction so that the terminal member of the inner peripheral conductive member 110 does not interfere with the outer peripheral conductive member 110? Alternatively, since it is necessary to dispose the conductive member 110 in the axial direction for each phase, the axial dimension of the wiring board 100 is increased. In the present embodiment, since the winding end 7a of the stator 2 is connected to the conductive member 110 by passing through in the axial direction, the terminal member is provided around the axial direction, or the conductive member 110 is provided for each phase. There is no need to displace each axially. Therefore, the axial dimension of the wiring board 100 can be reduced. Thus, the connection board 100 can be reduced in size in the radial direction and the axial direction. As a result, the rotating electrical machine 1 can be reduced in size.

  In the present embodiment, in particular, the coated flat wire 101 is formed to have a spiral shape having straight portions 101a to 101c extending linearly in the tangential direction of the arc. Here, when it is considered that the covered rectangular wire 101 formed in a simple spiral shape having no straight part is divided at a predetermined position, the radius of curvature of the conductive member 110 continuously changes. Difficulty in the work of drilling the through hole 113 and the wiring work of connecting the winding end 7a of the stator 2 through the through hole 113 will increase. On the other hand, in this embodiment, since the covered rectangular wire 101 is formed into a spiral shape having the straight portions 101a to 101c, the covered rectangular wire 101 is disposed along a concentric circle in a region other than the straight portions 101a to 101c. Thus, the conductive members 110 formed by the division can be arranged concentrically. As a result, subsequent drilling operations and wire connection operations are facilitated. In addition, these operations can be automated.

  In the present embodiment, in particular, the tapered hole 121 is provided at a position corresponding to the through hole 113 in the surface 122 on the anti-connection side of the insulating member 120. The taper hole 121 allows the winding end portion 7a of the stator 2 to be introduced into the through hole 113, thereby further facilitating the connection work and facilitating the automation of the connection work.

  In this embodiment, in particular, the conductive member 110 is formed by dividing the covered rectangular wire 101 formed in a spiral shape at a predetermined position using a general-purpose tool such as a drill or a punch press. Thereby, a special tool becomes unnecessary and a conductive member can be formed easily and inexpensively.

  In this embodiment, in particular, the covered rectangular wire 101 having a quadrangular cross section is used for the conductive member 110. Accordingly, for example, compared to a case where a round wire having a circular cross-sectional shape is used, it is easy to perform processing such as providing a through-hole 113 through the winding end portion 7a in the conductive member 110 or dividing at a predetermined position. The workability of the conductive member 110 is improved. Soldering is performed when the winding end portion 7a of the stator 2 is connected to the conductive member 110. By using the coated rectangular wire 101, soldering can be performed on a flat surface, so that workability is improved. Can be improved. Further, for example, when a flat wire without covering is used, the radial gap between the conductive members 110 needs to be a certain size or more in order to ensure insulation. However, as in the present embodiment, the covering flat wire 101 is used. By using this, the gap can be made as small as possible, and the radial dimension of the wiring board 100 can be further reduced.

<Modification>
In addition, it is not restricted to the said embodiment, A various deformation | transformation is possible within the range which does not deviate from the meaning and technical idea.

  For example, in the above embodiment, the case where the connection pattern has two systems of star connection has been described as an example, but the present invention is not limited to this, and by appropriately changing the number of turns, the dividing position, and the connection position of the covered rectangular wire 101, Various connection patterns such as Δ connection and V connection can be handled.

  In the above description, the case where the rotating electrical machine 1 is a three-phase AC motor having 12 windings 7 has been described as an example. However, the number of windings 7 can be changed as appropriate, and a single-phase AC motor or a DC motor can be used. It can be applied to motors other than three-phase AC. That is, the type of the electric motor is not limited, and can be applied to various electric motors as long as the end of the winding of the stator is connected with a predetermined connection pattern.

  In the above description, the coated rectangular wire 101 having the covering material 112 is used for the conductive member 110, but a rectangular wire without the covering material 112 may be used. Moreover, it is not always necessary to use a flat wire, and a wire having a cross-sectional shape other than a square (such as a round wire) may be used.

  In the above description, the case where the rotating electrical machine 1 is an inner rotor type in which the rotor 3 is provided inside the stator 2 has been described as an example, but an outer rotor type in which the rotor 3 is provided outside the stator 2 is described. The present invention can also be applied to a rotating electric machine. Furthermore, although the case where the rotating electrical machine 1 is an electric motor has been described as an example, the present invention can also be applied to the case where the rotating electrical machine 1 is a generator.

  In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination.

  In addition, although not illustrated one by one, the above-mentioned embodiment and each modification are implemented with various modifications within a range not departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 Rotating electrical machine 2 Stator 3 Rotor 7 Winding 7a End part 100 Connection board 101 Coated flat wire (conductive wire, flat wire)
DESCRIPTION OF SYMBOLS 110 Conductive member 110uc Linear part 110vc Linear part 113 Through-hole 114 Concave-curved surface 120 Insulating member 121 Tapered hole S Defect part

Claims (7)

A method of manufacturing a rotating electrical machine comprising: a rotor and a stator; and a connection board for connecting the end of the stator winding with a predetermined connection pattern,
The wiring board is
A first step of forming a conductive wire in a spiral shape;
A second step of covering at least part of the surface of the spirally shaped wire with an insulating material;
And a third step of dividing the wire covered with the insulating material at a predetermined position in the circumferential direction. The manufacturing process of the wiring board is as follows:
2. The method of manufacturing a rotating electrical machine according to claim 1, further comprising a fourth step of providing a through hole in the wire, and allowing the end of the winding to pass through the through hole in the rotation axis direction. In the first step,
The method of manufacturing a rotating electrical machine according to claim 2, wherein the wire is formed so as to have a spiral shape having a linear portion extending linearly in a tangential direction of the arc. In the fourth step,
A taper hole is provided at a position corresponding to the through hole of the insulating member formed of the insulating material, and an end portion of the winding is passed through the through hole of the wire through the tapered hole. Item 4. A method for manufacturing a rotating electrical machine according to Item 2 or 3. In the third step,
The method of manufacturing a rotating electrical machine according to any one of claims 1 to 4, wherein the wire is divided at a predetermined circumferential position by using a drill or a punch press. In the first step,
6. The method of manufacturing a rotating electrical machine according to claim 1, wherein the rectangular wire is formed into a spiral shape. A wiring board manufacturing method provided in a rotating electrical machine having a rotor and a stator, wherein the ends of the windings of the stator are connected with a predetermined connection pattern,
A first step of forming a conductive wire in a spiral shape;
A second step of covering at least part of the surface of the spirally shaped wire with an insulating material;
And a third step of dividing the wire covered with the insulating material at a predetermined circumferential position.

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