JP7496338B2 - How to remove the coating from rectangular wire - Google Patents

Description

The present invention relates to a method for removing the coating from rectangular wire.

In recent years, in light of environmental issues, there has been an accelerating trend to adopt motors in the drive systems and peripheral devices of vehicles such as electric vehicles and hybrid vehicles. Motors installed in such vehicles are required to be small due to the space available for installation, but they are often also required to have high output to improve the driving performance of the vehicle.

Here, in order to increase the motor's output, it is necessary to increase the current flowing through the stator coil. On the other hand, in order to efficiently increase the current flowing through the coil under conditions where space is limited, it is possible to construct the coil from a rectangular wire (rectangular conductor) that has a roughly rectangular cross section and a relatively high space factor.

These rectangular wires are arranged in a predetermined order in slots formed at regular intervals around the circumference of the stator core to form three-phase coils. Meanwhile, these rectangular wires are covered with an insulating coating. Therefore, in order to electrically connect the rectangular wires that make up each phase, it is necessary to remove the insulating coating from the ends of the rectangular wires and join the ends of the rectangular wires together.

Patent document 1 discloses a method in which a rectangular wire is cut to a predetermined length in advance, rotated around its longitudinal axis, and conveyed in a predetermined direction, and the insulating coating on the short side and long side of the rectangular wire is removed in multiple cutting processes arranged along the conveying direction, and the corners of the rectangular wire are chamfered to remove the insulating coating from the entire circumference of the rectangular wire.

JP 2015-89837 A

However, when considering reducing the cost required for this type of processing, it is important to keep not only the initial capital investment but also the running cost as low as possible. As described in Patent Document 1, if both the removal of the insulating coating and the chamfering are performed by cutting, the number of cutting blades required will be large, and the replacement cost due to wear of the cutting blades will hinder low running costs. In order to solve this problem, for example, a method can be considered in which the chamfering by cutting is omitted and the insulating coating 2 of the rectangular wire 1 is removed from the conductor 3 only by cutting along each side 2a, 2b (see Figure 13). However, the corners 4 of the actual rectangular wire 1 have a cross-sectional R shape with a corresponding radius of curvature, as shown in Figure 14. Therefore, as described above, if only cutting along each side 2a, 2b is performed, there is a high possibility that part of the insulating coating 2 covering the corners 4 will remain on the rectangular wire 1 after cutting.

In light of the above, the technical problem to be solved in this specification is to make it possible to remove the insulating coating of a rectangular wire from its entire circumference without missing anything while also reducing running costs.

The above problem is solved by the coating removal method for rectangular wire according to the present invention. That is, this coating removal method is a method for removing an insulating coating from a rectangular wire, and includes a first coating removal step for removing the insulating coating on a first side that constitutes a cross section of the rectangular wire, and a second coating removal step for removing the insulating coating on a second side that constitutes the cross section of the rectangular wire together with the first side and is perpendicular to the first side. The method is characterized in that it further includes a curvature radius reduction step for subjecting the rectangular wire to a predetermined molding before the second coating removal step, which is performed later among the first and second coating removal steps, to reduce the curvature radius of the corner between the two sides.

In this way, in the method for removing the coating from a rectangular wire according to the present invention, the rectangular wire is subjected to a predetermined molding process before the process of removing the insulating coating from the first side of the rectangular wire that constitutes the cross section (first coating removal process) and the process of removing the insulating coating from the second side that is perpendicular to the first side (second coating removal process), which is performed later, to reduce the radius of curvature of the corner between the two sides. In this way, before completing the removal process of the insulating coating along all sides, the radius of curvature of the corner is reduced by molding, in other words, the corner is made sharper, so that the insulating coating covering the corner can be deformed to a state that follows the insulating coating of each side. Therefore, by performing the coating removal process on each side, the insulating coating remaining on the corner can be completely removed or reduced as much as possible. Therefore, the chamfering process of the corners by cutting can be omitted, and the insulating coating in the required area of the rectangular wire can be removed all around without omission by only cutting along each side. Furthermore, with mold forming, there is no need to worry about running costs, as there are with cutting blades, so even if a molding die is added to increase the curvature of the corners, it is possible to reduce running costs by the amount that the number of cutting blades can be reduced compared to conventional methods.

The coating removal method for rectangular wire according to the present invention may further include a chamfering process for performing chamfering on the corners by molding after the first coating removal process, which is performed first among the first and second coating removal processes.

By performing chamfering on the corners using mold forming in this way, it is possible to form chamfers on the corners without producing cutting waste. This makes it possible to thoroughly remove the insulating coating from all around while reducing costs in terms of both running costs and material costs. In addition, by performing the chamfer forming process after the first coating removal process, which is performed first, it is possible to generate protruding deformations (also called burrs) in the insulating coating caused by the chamfer forming process on the second edge side. This makes it possible to reliably remove these protruding deformations together with the insulating coating on the second edge side in the subsequent second coating removal process.

As described above, the method for removing the coating from a rectangular wire according to the present invention makes it possible to thoroughly remove the insulating coating from the entire circumference of a rectangular wire while reducing running costs.

2 is a flowchart showing the steps of a main part of a method for manufacturing a rectangular wire according to an embodiment of the present invention. 2 is a YZ cross-sectional view of the rectangular wire before the curvature radius reduction process shown in FIG. 1 is performed. 2 is a YZ cross-sectional view of the rectangular wire after the curvature radius reduction process shown in FIG. 1 is performed. FIG. 11 is an XY plan view showing the concept of the short side pre-cutting process. 2 is a YZ cross-sectional view of the rectangular wire before the short side coating removal process shown in FIG. 1 is performed. 2 is a YZ cross-sectional view of the rectangular wire after the short side coating removal process shown in FIG. 1 has been performed. FIG. 1 is an XZ plan view of a rectangular wire illustrating the concept of the long side pre-cut process. 2 is a YZ cross-sectional view of a rectangular wire illustrating the concept of the chamfering process shown in FIG. 1. 2 is a YZ cross-sectional view of the rectangular wire before the long side coating removal process shown in FIG. 1 is performed. 2 is a YZ cross-sectional view of the rectangular wire after the long side coating removal process shown in FIG. 1 has been performed. 2 is an XZ plan view of a rectangular wire illustrating the concept of the cutting process shown in FIG. 1. FIG. 2 is a perspective view of the end of the rectangular wire after coating removal and chamfering. FIG. 2 is a cross-sectional view of a rectangular wire illustrating the concept of coating removal processing of the rectangular wire. FIG. 14 is an enlarged view of a portion A of the rectangular wire shown in FIG. 13.

The details of the manufacturing method for rectangular wire according to one embodiment of the present invention will be explained below with reference to the drawings.

Figure 1 shows the steps of the main part of the manufacturing method of the rectangular wire. That is, the manufacturing method of the rectangular wire according to this embodiment includes a coating removal process for removing the insulating coating of the rectangular wire and a cutting process S5 for cutting the rectangular wire from which the coating has been removed. The coating removal process includes a curvature radius reduction process S1, a short side coating removal process S2, a chamfering process S3, and a long side coating removal process S4. Here, the short side coating removal process S2 corresponds to the first coating removal process according to the present invention, and the long side coating removal process S4 corresponds to the second coating removal process according to the present invention. Below, each process S1 to S4 will be mainly explained. In the following, the longitudinal direction of the rectangular wire is conveniently defined as the X direction, and in a virtual cross section of the rectangular wire perpendicular to the X direction, the long side direction of the rectangular wire is conveniently defined as the Y direction, and the short side direction is conveniently defined as the Z direction, and the directions will be explained.

(S1) Step of Reducing Radius of Curvature In step S1, the radius of curvature of the corners of the rectangular wire is reduced by a predetermined molding before the subsequent steps of the short side coating removal step S2 and the long side coating removal step S4. In this embodiment, as shown in Fig. 2, the radius of curvature of the corners of the rectangular wire 1, more precisely, the radius of curvature of the corners 4 of the conductor 3 covered with the insulating coating 2, is reduced by performing a predetermined molding on the rectangular wire 1, which is the rectangular wire 1a (see Fig. 12 described later) before being cut to a predetermined length. Here, a short side molding die 11 having a pair of flat press surfaces 11a, 11a and a long side molding die 12 having a pair of flat press surfaces 12a, 12a are used to press the area of the rectangular wire 1 where the insulating coating 2 is to be peeled off (area 5 to be peeled off: see FIG. 4 described later) in the Y and Z directions, thereby deforming the conductor 3 so that the surfaces of the corners 4 provided at the four corners of the conductor 3 are aligned with the short side flat surfaces 3a and long side flat surfaces 3b of the adjacent conductor 3 (see FIG. 3). As a result, the corners 4 are deformed to protrude so as to fill the space between the surface of the insulating coating 2 located on the outer periphery of the corners 4 and each of the press surfaces 11a, 12a, and as a result, the radius of curvature of the corners 4 is reduced.

(S6) Short Side Pre-Cutting Step In addition, in this embodiment, when the corner 4 forming step (curvature radius reduction step S1) is performed by the short side and long side forming dies 11, 12, a slit 6 is formed in the flat portion 2a on the short side (also called the edgewise side) of the rectangular wire 1 in the insulating coating 2 covering the outer periphery of the rectangular wire 1 (short side pre-cutting step S6). This slit 6 is formed along the width direction (Z direction in this embodiment) of the flat portion 2a on the short side. In addition, the slit 6 is formed at a predetermined interval in the longitudinal direction (X direction in this embodiment) of the rectangular wire 1. In this embodiment, a pair of slits 6, 6 is formed for each of a pair of flat portions 2a facing each other through the conductor 3 (see FIG. 4). This defines the peeling-premium region 5. That is, the region between the pair of slits 6, 6 is defined as the peeling-premium region 5.

(S2) Short Side Coating Removal Step In this step S2, a coating removal process is performed on a predetermined area (area 5 to be peeled) of the rectangular wire 1 that has been subjected to a predetermined molding process, using a predetermined coating removal means. Any coating removal means can be used at this time. For example, as shown in FIG. 5, a peeling blade member 13 is pressed against a portion between a pair of slits 6 (see FIG. 4) on the flat portion 2a on the short side of the rectangular wire 1, and slid in the width direction (here, Z direction), so that the portion of the flat portion 2a partitioned by the pair of slits 6 is peeled off and removed from the rectangular conductor 3. The above-mentioned peeling operation (removal operation) is performed on a pair of flat portions 2a that face each other through the conductor 3. At the completion of the above-mentioned removal operation (cutting process), as shown in FIG. 6, only the flat portion 2a on the short side of the insulating coating 2 of the rectangular wire 1 is removed. On the other hand, the flat portion 2 b on the long side (also called the flatwise side) is still attached to the long side flat surface 3 b of the conductor 3 .

In this case, in order to reliably remove (peel off) all of the flat portion 2a on the short side of the insulating coating 2, it is preferable to set the cut line L1 at a position slightly shifted toward the conductor 3 from the boundary between the insulating coating 2 and the conductor 3. In the illustrated example, the position of the blade member 13 relative to the rectangular wire 1 is set so that the Y-direction position of the blade surface 13a of the blade member 13 coincides with the Y-direction position of the cut line L1. Here, since the corner 4 of the conductor 3 is sharpened (the radius of curvature is reduced) in the previous process S1, peeling off the insulating coating 2 (flat portion 2a) at the above-mentioned cut line L1 position results in the insulating coating 2 covering the corner 4 being completely removed (as shown in FIG. 6) or being slightly left on the corner 4.

(S7) Long Side Precutting Process In addition, in this embodiment, in conjunction with the short side flat portion 2a removal process S2, a slit 7 is formed in the flat portion 2b on the long side of the rectangular wire 1 of the insulating coating 2 covering the outer periphery of the rectangular wire 1 (long side precutting process S7 shown in FIG. 7). The slit 7 is formed along the width direction (Y direction in this embodiment) of the flat portion 2b on the long side. The slit 7 is also formed at a predetermined interval in the longitudinal direction (X direction in this embodiment) of the rectangular wire 1. In this embodiment, a pair of slits 7, 7 is formed for each of a pair of flat portions 2b facing each other via the conductor 3 (see FIG. 7). This defines the longitudinal range of the flat portion 2b to be removed (peeled off) in the subsequent long side coating removal process S4.

(S3) Chamfering Process In this process S3, the corners 4 that have been sharpened in the previous process (curvature radius reduction process S1) are chamfered by molding. In this embodiment, the corners 4 of the rectangular wire 1 after the short side coating removal process S2 are chamfered by molding. Any molding means can be used in this process. For example, as shown in FIG. 8, a pair of molds 14 having molding surfaces that can mold the short side portion of the rectangular wire 1, including the corners 4, into a predetermined shape by clamping in the long side direction (Y direction) are used. Each of the molds 14 in this illustrated example has a first molding surface 14a that is tapered and used to perform C-chamfering on the corners 4, and a second molding surface 14b that is flat and used to mold the flat surface 3a on the short side of the conductor 3.

The peeling area 5 of the rectangular wire 1 is placed between the pair of molding dies 14, 14 having the above configuration, and the pair of molding dies 14, 14 are brought close to each other (clamped), so that the corners of the rectangular wire 1 (corner 4 of the conductor 3) and the short side flat surface 3a of the exposed conductor 3 are molded by the first and second molding surfaces 14a, 14b. As a result, a tapered chamfered portion 8 is formed at the corner 4. In addition, at the same time that the corner 4 is molded by the first molding surface 14a, the short side flat surface 3a of the conductor 3 adjacent to the corner 4 on the short side is molded by the second molding surface 14b that is continuous with the first molding surface 14a, so that a part of the corner 4 is deformed toward the long side along the first molding surface 14a, and the end 2b1 of the insulating coating 2 (the flat portion 2b on the long side) that covered the long side of the corner 4 is pressed and bent. In this manner, the chamfering of the corner 4 is performed.

(S4) Long Side Coating Removal Step In this step S4, a coating removal process is performed on a predetermined area (a region 5 to be peeled) of the rectangular wire 1 in which the corners 4 have been chamfered by molding using a predetermined coating removal means. Any coating removal means can be used at this time. For example, as shown in FIG. 9, a peeling blade member 15 is pressed against a portion between a pair of slits 7, 7 (see FIG. 7) in the flat portion 2b on the long side of the rectangular wire 1, and slid in the width direction (here, the Y direction), so that the portion of the flat portion 2b partitioned by the pair of slits 7, 7 is peeled off and removed from the conductor 3. The above-mentioned peeling operation (removal operation) is performed on a pair of flat portions 2b facing each other via the conductor 3. As a result, the insulating coating 2 in the region 5 to be peeled off of the rectangular wire 1 is removed over the entire circumference, and the conductor 3 having chamfered portions 8 at the four corners is exposed (see FIG. 10).

As in the short side coating removal step S2, from the viewpoint of reliably removing (peeling off) all of the flat portions 2b on the long side of the insulating coating 2, it is preferable to set the cut line L2 at a position slightly shifted toward the conductor 3 from the boundary between the insulating coating 2 and the conductor 3. In the illustrated example, the position of the blade member 15 relative to the rectangular wire 1 is set so that the Z-direction position of the blade surface 15a of the blade member 15 coincides with the Z-direction position of the cut line L2. Here, the end 2b1 of the insulating coating 2 is bent in a direction away from the conductor 3 during the chamfering forming step S3. Therefore, as described above, by peeling off the flat portion 2b of the insulating coating 2 from the conductor 3 near the boundary between the insulating coating 2 and the conductor 3, all of the flat portions 2b on the long side, including the end 2b1, can be reliably removed from the conductor 3.

(S5) Cutting step After removing all of the insulating coating 2 from the necessary areas (areas 5 to be peeled) as described above, the removed areas are cut by a predetermined cutting means (e.g., shearing). As a result, a rectangular wire 1a is obtained with the conductor 3 exposed at the longitudinal end, as shown in FIG. 11.

Then, each corner of the conductor 3, specifically, the corner between the tip surface 3c of the conductor 3 located at the tip end side of the rectangular wire 1a and the long side flat surface 3b, and the corner between the tip surface 3c and the short side flat surface 3a are chamfered. As a result, as shown in FIG. 12, a first chamfered portion 9a is formed between the short side flat surface 3a and the long side flat surface 3b, a second chamfered portion 9b is formed between the tip surface 3c and the long side flat surface 3b, and a third chamfered portion 9c is formed between the tip surface 3c and the short side flat surface 3a. The first chamfered portion 9a is a part of the chamfered portion 8 formed in the chamfer forming process S3, and is obtained by removing the insulating coating 2 (flat portion 2b) on the long side in the long side coating removal process S4.

The means for forming the second and third chamfered portions 9b, 9c (chamfering means) is arbitrary, with die forming being a suitable example. The order in which the chamfered portions 9b, 9c are formed (the order in which the chamfers are processed) is also arbitrary, and may be performed after the cutting step S5 or before the cutting step S5. If the chamfered portions are performed before the cutting step S5, they may be performed simultaneously with the above-mentioned steps S1 to S5. As an example, the third chamfered portion 9c may be performed simultaneously with the removal process of the flat portion 2a on the short side (short side coating removal step S2), and the second chamfered portion 9b may be performed simultaneously with the cutting process of the conductor 3 (cutting step S5).

After the processing of the end of the rectangular wire 1a is completed in this manner, the rectangular wire is completed as a coil segment by performing a predetermined bending process, etc. (not shown).

As described above, in the manufacturing method of the rectangular wire according to the present embodiment, before the coating removal step S4, which is performed later among the step S2 of removing the insulating coating 2 (2a) on the short side of the rectangular cross section of the rectangular wire 1 and the step S4 of removing the insulating coating 2 (2b) on the long side, a predetermined molding is performed on the stripping area 5 of the rectangular wire 1 to reduce the radius of curvature of the corner 4 of the conductor 3. In this way, by reducing the radius of curvature of the corner 4 by molding before completing the removal process of the insulating coating 2 (2a, 2b) along all sides, the part of the insulating coating 2 covering the corner 4 is deformed in the direction along the insulating coating 2 of each side (the short side flat part 2a and the long side flat part 2b), so that it is possible to avoid a situation in which a part of the insulating coating 2 remains on the surface of the corner 4 after the coating removal process of each side is performed. Therefore, the chamfering of the corners 4 by cutting can be omitted, and all of the insulating coating 2 in the intended peeling area 5 can be reliably removed by cutting along each side (each coating removal step S2, S4). In addition, with die molding, there is no need to worry about running costs as with cutting blades, so even if molding dies 11, 12 (see Figure 2) are added to increase the curvature of the corners 4, it is possible to reduce running costs by the amount that the number of cutting blades can be reduced compared to conventional methods.

In addition, in this embodiment, the corners 4 are chamfered by molding, so that the chamfers can be formed on the corners 4 without producing cutting waste. This makes it possible to reliably remove all of the insulating coating 2 in the intended peeling area 5 while reducing costs in terms of both running costs and material costs. In addition, by performing the chamfer forming process S3 after the short side coating removal process S2, which is performed first, burrs (protruding end 2b1) of the insulating coating 2 can be generated on the long side. This makes it possible to reliably remove this protruding end 2b1 together with the insulating coating 2 (2b) on the long side in the subsequent long side coating removal process S4.

In particular, as in this embodiment, by performing the chamfering forming process S3 after the short side coating removal process S2 and then performing the long side coating removal process S4, the end 2b1 of the insulating coating 2 (2b) can be reliably removed, and can be removed at the same time as the remaining insulating coating 2 (2b) is removed (efficiently). In addition, if the insulating coating 2 (2b) on the long side is removed by cutting after chamfering, the cutting distance (cutting distance in the Y direction) can be short, and the load on the blade member 15 is reduced. This also makes it possible to suppress wear on the blade member 15 and reduce the running costs associated with replacing the blade member 15.

Although one embodiment of the present invention has been described above, the method for removing the coating from a rectangular wire according to the present invention can have configurations other than those described above without departing from the spirit of the method.

For example, in the above embodiment, the corner 4 of the conductor 3 is deformed by pressing the area 5 to be peeled of the rectangular wire 1 in the Y and Z directions using the molds 11 and 12, both of which have flat press surfaces 11a and 12a. However, molding may be performed in other ways. For example, although not shown, molding may be performed with the press surface 11a (12a) of at least one of the molds 11 (12) having a convex shape. In this case, the corner 4 of the conductor 3 is shaped to protrude outward from the flat surfaces 3a and 3b along each side, so that the insulating coating 2 covering the corner 4 can be more reliably removed by the subsequent coating removal process. Specific examples of the convex shape include a combination of a flat surface and a tapered surface, or a convex curved shape such as a cross-sectional arc shape.

In addition, with regard to the order of the curvature radius reduction step S1, the above embodiment illustrates a case in which the curvature radius reduction step S1 is performed before both the short side coating removal step S2 and the long side coating removal step S4, but of course this is not limited to this. For example, the order of the curvature radius reduction step S1 can be set arbitrarily as long as it is performed before the subsequent coating removal step, such as after the short side coating removal step S2 and before the long side coating removal step S4.

In addition, with regard to the chamfer forming process S3, the present embodiment illustrates a case in which the chamfer forming process S3 is performed after the short side coating removal process S2 and before the long side coating removal process S4, but of course this is not limited to this. For example, although not shown in the figure, the chamfer forming process S3 may be performed after both the short side coating removal process S2 and the long side coating removal process S4 are performed. In short, the chamfer forming process S3 can be performed in any order as long as at least one of the coating removal processes S2 (S4) and the curvature radius reduction process S1 has been performed.

The order of the short side coating removal process S2 and the long side coating removal process S4 is not limited to the embodiment described above. For example, the chamfer forming process S3 may be performed after the long side coating removal process S4, and then the short side coating removal process S2 may be performed.

Reference Signs List 1 Flat wire 1a Flat wire 2 Insulating coating 2a Short side flat portion 2b Long side flat portion 2b1 End 3 Conductor 3a Short side flat surface 3b Long side flat surface 3c Tip surface 4 Corner 5 Planned peeling area 6, 7 Cut 8, 9a, 9b, 9c Chamfered portion 11, 12 Mold 13 Blade member 14 Mold 15 Blade member L1, L2 Cut line S1 Curvature radius reduction step S2 Short side coating removal step S3 Chamfer forming step S4 Long side coating removal step S5 Cutting step S6 Short side pre-cut step S7 Long side pre-cut step

Claims (2)

A method for removing an insulating coating from a rectangular wire having a rectangular cross section, comprising the steps of:
A coating removal method for a rectangular wire, comprising a first coating removal step for removing an insulating coating on a first side of the rectangular cross section of the rectangular wire, and a second coating removal step for removing an insulating coating on a second side of the rectangular cross section of the rectangular wire together with the first side and perpendicular to the first side,
This method for removing a coating on a flat wire further comprises, prior to the first coating removal process, which is performed first among the first and second coating removal processes, a curvature radius reduction process of pressing the area of the flat wire from which the insulating coating is to be peeled off in a direction along the first and second sides using a first edge side molding die having a pair of flat press surfaces facing the first edge side of the flat wire and a second edge side molding die having a pair of flat press surfaces facing the second edge side of the flat wire, thereby reducing the curvature radius of the corner between the two sides. The coating removal method for a rectangular wire according to claim 1, further comprising a chamfering process, which is performed after the first coating removal process, which is performed first among the first and second coating removal processes, by clamping the mold in a direction along the second side, to perform chamfering on the corners using a pair of molds having a first molding surface that is tapered and for performing C-chamfering on the corners, and a second molding surface that is flat and for performing molding on the flat surface on the first side.

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