Coil manufacturing apparatus and coil manufacturing method

Abstract

Disclosed is a production method that is for a coil having an insulating film and that comprises: a preparation step for preparing a plurality of coil materials before application of the insulating film; and an electrodeposition coating step for generating an electric potential difference between a first electrode to which the coil materials are connected and a second electrode in an electro-coating tank, in a state where the coil materials are immersed in the electro-coating tank. In the electrodeposition coating step, positioning of the coil materials and the second electrode is performed such that, with respect to one or more target sites located at the same position among the respective coil materials, the shortest distances between the second electrode and the target sites of the respective coil materials become substantially equal to one another.

Description

[Technical field]

[0001] The present disclosure relates to a coil manufacturing apparatus and a coil manufacturing method. [Background technology]

[0002] A technique is known in which an insulating film is applied simultaneously to a plurality of coils by electrocoating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-115240 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional techniques described above, there is significant variation between coil materials in terms of their positional relationship with the electrodes in the electrocoating tank, making it difficult to apply an insulating film with reduced variation to each coil material in a relatively short electrocoating time.

[0005] Therefore, in one aspect, an object of the present disclosure is to provide an insulating film with reduced variation to each coil material in a relatively short electrocoating time. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a method for manufacturing a coil having an insulating film, the method comprising the steps of: a preparation step of preparing a plurality of coil materials before the insulating film is applied; an electrodeposition coating process for generating a potential difference between a first electrode connected to the coil materials and a second electrode in the electrodeposition tank while the coil materials are immersed in the electrodeposition tank; A coil manufacturing method is provided in which, in the electrocoating process, the multiple coil materials and the second electrode are positioned relative to each other so that, for at least one target portion at the same position on the multiple coil materials, the shortest distance between the target portion and the second electrode among the multiple coil materials is approximately the same. Effect of the Invention

[0007] In one aspect, the present disclosure makes it possible to apply an insulating film with reduced variation to each coil blank in a relatively short electrocoating time. [Brief description of the drawings]

[0008] [Figure 1] 4 is a cross-sectional view taken along the axial direction of the stator in a state in which coil pieces are assembled to the stator core. FIG. [Figure 2A] FIG. 2 is an illustration of a coil piece according to an example. [Figure 2B] FIG. 11 is an explanatory diagram of a coil piece according to another example. [Diagram 3] FIG. 2 is a schematic cross-sectional view of a coil piece. [Figure 4A] FIG. 2 is an explanatory diagram of an outline of a coil manufacturing apparatus and an electrodeposition coating process. [Figure 4B] FIG. 2 is a schematic plan view showing one workpiece. [Diagram 5] FIG. 4 is a diagram illustrating conceptual features related to a second electrode. [Figure 6] 4 is a perspective view showing a schematic relationship between a plurality of workpieces immersed in an electrodeposition tank and a second electrode. FIG. [Figure 7] FIG. 7 is an enlarged view of the periphery of the workpiece in FIG. 6. [Figure 8] 6A and 6B are diagrams showing the relationship between a transition portion and a second electrode. [Figure 9] FIG. 11 is an explanatory diagram of an example of a suitable arrangement when two or more rows of workpieces in the Y direction are simultaneously immersed in an electrodeposition bath to perform an electrodeposition coating process. [Figure 10A] FIG. 11 is an explanatory diagram of the configuration of a second electrode according to a comparative example. [Figure 10B]FIG. 13 is a diagram showing an analysis result for a comparative example. [Figure 11] FIG. 1 is a diagram showing an analysis result for Example 1. [Figure 12] FIG. 13 is a diagram showing an analysis result relating to the difference in film thickness between a center side surface of a workpiece and its opposite side surface. [Figure 13] FIG. 4 is an explanatory diagram of a modified example of the second electrode in the first embodiment. [Figure 14] 14 is an explanatory diagram of various parameters relating to the positional relationship between the second electrode and the workpiece in the modified example of FIG. 13. FIG. [Figure 15] FIG. 11 is an explanatory diagram of another modified example of the second electrode of the first embodiment. [Figure 16] 10 is an explanatory diagram of a modification of the center electrode of the second electrode in the first embodiment. FIG. [Figure 17] 13 is an explanatory diagram of another modified example of the center electrode of the second electrode in the first embodiment. FIG. [Figure 18] 13 is an explanatory diagram of still another modified example of the center electrode of the second electrode in the first embodiment. FIG. [Figure 19] FIG. 11 is a perspective view showing the relationship between a second electrode and a plurality of workpieces in the second embodiment. [Figure 20] FIG. 13 is a diagram showing an analysis result for Example 2. [Figure 21] FIG. 11 is an explanatory diagram of a modified example of the second electrode in the second embodiment. [Figure 22] 13 is an explanatory diagram of various parameters relating to the positional relationship between the second electrode and the workpiece in the second embodiment. FIG. [Figure 23] 13 is an explanatory diagram of a modified example of the second electrode with respect to the center electrode of the second embodiment. FIG. [Figure 24] 13 is an explanatory diagram of a further modified example of the center electrode of the second electrode in the second embodiment. FIG. [Diagram 25] 13 is an explanatory diagram of a further modified example of the center electrode of the second electrode in the second embodiment. FIG. [Figure 26] 13 is an explanatory diagram of a modified example having a configuration that does not have a center electrode. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not intended to be limiting, and shapes and the like in the drawings may be partially exaggerated for the sake of explanation.

[0010] In the following, first, the coil manufactured by the coil manufacturing method of the present embodiment will be generally described, and then the coil manufacturing method will be described.

[0011] Fig. 1 is a cross-sectional view along the axial direction of the stator 10 in a state in which the coil pieces 52 are assembled to the stator core 112. Fig. 2A is a front view of one of the coil pieces 52 among the plurality of coil pieces 52. Fig. 2A shows one coil piece 52 in a state before being formed. Fig. 2B is a three-view diagram of one coil piece 52' according to another embodiment. Fig. 3 is a schematic cross-sectional view of the coil piece 52.

[0012] The stator coils 114 include a U-phase coil, a V-phase coil, and a W-phase coil (hereinafter, when U, V, and W are not distinguished, they are referred to as "phase coils"). The base end of each phase coil is connected to an input terminal (not shown), and the end of each phase coil is connected to the end of the other phase coil to form a neutral point. In other words, the stator coils 114 are star-connected. However, the connection mode of the stator coils 114 may be changed as appropriate depending on the required motor characteristics, etc. For example, the stator coils 114 may be delta-connected instead of star-connected.

[0013] Each phase coil of the stator coil 114 is formed by connecting a plurality of coil pieces 52. The coil pieces 52 are in the form of segment coils (segment conductors) obtained by dividing the phase coil into units that are easy to assemble (for example, units that can be inserted into two slots 23). As shown in FIG. 3, the coil pieces 52 are formed by covering a linear conductor (rectangular wire) 120 having a substantially rectangular cross section with an insulating film 130. Here, the linear conductor is formed of copper, as an example. However, in a modified example, the linear conductor may be formed of another conductive material such as iron. The cross-sectional shape of the linear conductor may be other than rectangular.

[0014] In the example shown in Fig. 2A, one coil piece 52 may be formed into a generally U-shape having a pair of linear slot-accommodated portions 50 and a transition portion 54 connecting the pair of slot-accommodated portions 50. The transition portion 54 on the other axial side (upper side in Fig. 2A) may be formed by shaping in the circumferential direction from the state shown in Fig. 2A. A joint portion 40 that is joined to a joint portion 40 of a transition portion 54 of another coil piece 52 is set at an end of the transition portion 54 on the other axial side (upper side in Fig. 2A).

[0015] When the coil pieces 52 are assembled to the stator core 112, the pair of slot housing portions 50 are inserted into the slots 23 between the teeth 22 (see FIG. 1). In this case, the coil pieces 52 can be assembled, for example, in the axial direction.

[0016] 1 are inserted into each slot 23 in a radially aligned manner. Thus, a plurality of circumferentially extending transition portions 54 are arranged radially at both axial ends of the stator core 112. The transition portions 54 form coil ends.

[0017] Coil pieces 52 may be wound around stator core 112 in a lap winding form. In the example shown in Fig. 2A, lower transition portion 54 has offset portion 521B that is offset from each other by one layer in the radial direction.

[0018] In the example shown in FIG. 2B, one coil piece 52' is formed by coupling a segment conductor 52A on one axial side to a segment conductor 52B on the other axial side.

[0019] Each of the segment conductors 52A and 52B may be formed in a substantially U-shape having a pair of linear slot-receiving portions 50 and a bridge portion 54 connecting the pair of slot-receiving portions 50.

[0020] 2B, one of the slot-accommodating portions 50 on both circumferential sides of the segment conductor 52A and the segment conductor 52B can be coupled, while the other is offset from the other in the radial direction by one layer. Specifically, the segment conductor 52A and the segment conductor 52B each have offset portions 521A and 521B at the tops of the opposing surfaces 42, and the offset portions 521A and 521B are offset in opposite radial directions.

[0021] As shown in Fig. 2B, the segment conductors 52A and 52B constituting one coil piece 52' are joined at the joining portions 40 of the slot-accommodated portions 50 on one side of the slot-accommodated portions 50 on both circumferential sides. In this case, the slot-accommodated portion 50 on the other side is joined to another coil piece 52. In this case, the joining portions 40 have opposing surfaces 42 that are entirely opposed to each other in the radial direction and come into surface contact with each other, and the joining portions 40 are joined together with the opposing surfaces 42 overlapping each other.

[0022] 1 to 3 show the stator core 112 and the stator coil 114 having a specific structure, the structure of the stator core 112 and the stator coil 114 is arbitrary as long as the stator coil 114 has the insulating film 130. The winding method of the stator coil 114 is also arbitrary, and it may be a winding method other than the lap winding type described above, such as a wave winding type.

[0023] Next, the coil manufacturing method of this embodiment will be described in detail with reference to FIG. 4A and subsequent figures.

[0024] The coil manufacturing method of this embodiment includes a preparation step of preparing a coil material before the insulating film 130 is applied and after forming. The formed coil material is formed, for example, by bending a linear conductor. The formed coil material may be only partially formed, for example, as in the coil piece 52 shown in FIG. 2A, or may be completely formed into a shape corresponding to the segment conductors 52A and 52B, for example, as in the coil piece 52' shown in FIG. 2B. In this embodiment, the coil material (hereinafter also referred to as "workpiece W") prepared in the preparation step has a substantially U-shaped shape, as shown in FIG. 4B.

[0025] The coil manufacturing method of the present embodiment includes an electrodeposition coating process in which an insulating film 130 is applied by electrodeposition coating to the workpiece W prepared in the preparation process. Note that other processes may be included between the preparation process and the electrodeposition coating process.

[0026] The portion of the workpiece W to which the insulating film 130 is applied may be the entire workpiece W or a part of the workpiece W. In this embodiment, as an example, the portion of the workpiece W to which the insulating film 130 is applied is substantially the entire workpiece W (for example, the entire workpiece W excluding a portion corresponding to the joint portion 40 of the coil pieces 52).

[0027] Fig. 4A is an explanatory diagram of an outline of the coil manufacturing apparatus 1 and the electrodeposition coating process. Fig. 4B is a schematic plan view showing one workpiece W.

[0028] As shown in FIG. 4A, the coil manufacturing apparatus 1 includes an electrodeposition tank 70, an electrode unit 73, and an electrodeposition processing unit 78.

[0029] The electrodeposition tank 70 is filled with paint. In Fig. 4A, the paint filled in the electrodeposition tank 70 is shown typically by a hatched area 72. The paint is a material for the insulating film 130, and may be an insulating paint containing polyamide-imide resin, polyimide resin, or the like. A plurality of workpieces W are immersed in the electrodeposition tank 70 before the insulating film 130 is applied and after molding.

[0030] The electrode section 73 forms a first electrode 74 electrically connected to the multiple workpieces W while the multiple workpieces W are immersed in the electrodeposition bath 70 , and a second electrode 76 within the electrodeposition bath 70 .

[0031] The electrodeposition processing unit 78 includes a DC power supply (rectifier) ​​781, which generates a potential difference between the first electrode 74 and the second electrode .

[0032] The electrodeposition coating process is performed with the workpiece W immersed in an electrodeposition bath 70, as shown in Fig. 4A. The workpiece W immersed in the electrodeposition bath 70 is in a state prior to the formation of the insulating film 130 on the coil pieces 52 described above. In the following, when referring to a specific portion of the workpiece W, the corresponding portion of the coil pieces 52 may be used for explanation. For example, in Fig. 4B, the portion of the workpiece W marked with the reference numeral 60 corresponds to the crossover portion 54 of the coil pieces 52, and hereinafter will also be referred to simply as the crossover portion 54 of the workpiece W.

[0033] When a potential difference is generated between the first electrode 74 and the second electrode 76 while the workpiece W is immersed in the electrodeposition tank 70, a direct current is generated through the paint (the paint film components electrophores). As a result, a paint film (paint film) is deposited (electrodeposited) on the surface of the workpiece W immersed in the electrodeposition tank 70. The paint film thus formed becomes the insulating film 130. The first electrode 74 is directly connected to the workpiece W, the second electrode 76 is disposed in the electrodeposition tank 70, and a direct current power source 781 is electrically connected between the first electrode 74 and the second electrode 76. The first electrode 74 and the second electrode 76 may be either positive or negative. During the electrodeposition coating process, the paint in the electrodeposition tank 70 may have a flow. For example, during the electrodeposition coating process, the paint may be supplied to the electrodeposition tank 70 from a supply side pipe (not shown) and discharged from a discharge side pipe (not shown). In this case, the paint is circulated through the electrodeposition tank 70 .

[0034] In Fig. 4A, the second electrode 76 is shown in a schematic diagram, and the features of this embodiment will be described below. In the following, the conceptual features of the second electrode 76 will first be described with reference to Fig. 5, and then specific configurations suitable for realizing the features will be described for each embodiment (Example 1 and subsequent examples described below) in Fig. 6 and subsequent figures.

[0035] Fig. 5 is a diagram for explaining conceptual features related to the second electrode 76. Fig. 5 conceptually shows a plurality of workpieces W immersed in an electrodeposition bath 70. The plurality of workpieces W have the same shape.

[0036] The second electrode 76 is configured so that the positional relationship between the second electrode 76 and the workpieces W is substantially the same when the workpieces W are immersed in the electrodeposition bath 70. Here, with regard to the positional relationship between the second electrode 76 (the same applies to the second electrodes 76A to 76J described below) and the workpieces W, "substantially the same positional relationship" may mean that the variation in the shortest distance between the target portion and the second electrode 76 among the workpieces W is less than 5 mm with respect to the portion at the same position in the workpieces W (hereinafter also referred to as the "target portion"). For example, in the example shown in FIG. 5, the shortest distance L1 between the target portion indicated by the arrow P1 and the second electrode 76 is uniquely determined for each workpiece W. The shortest distance L1 is the shortest spatial distance through the paint in the electrodeposition bath 70, but does not need to be measured precisely and may be, for example, a distance intended by design. This also applies to the shortest distances L2 and L3 related to the other target portions indicated by the arrows P2 and P3. Such a target area is at least a part of the range to be electrocoated, and may be any part (for example, the target area indicated by the arrow P2 or the arrow P3) or a specific part. For example, the target area may be any part within the range W2 mainly including the slot accommodating portion 50 as shown in FIG. 4B. In this embodiment, as a preferred example, the target area is any part of the range to be electrocoated (i.e., the entire workpiece W). The variation in the shortest distance is, for example, the difference between the minimum and maximum values ​​of the shortest distances L1 of the multiple workpieces W when the multiple workpieces W are immersed in the electrocoating tank 70.

[0037] In the electrocoating process, paint is more easily electrocoated in areas of the workpiece W where the electric flux density is relatively high than in areas where the electric flux density is relatively low, and therefore the thickness of the paint film tends to be large. Even in areas where the electric flux density was relatively high at the start of the electrocoating process, as the paint film thickness increases over time, the electric flux density becomes relatively low, so that when the time that multiple workpieces W are immersed in the electrocoating tank 70 (the time of the electrocoating process) becomes relatively long, the film thickness becomes uniform across the entire workpieces W.

[0038] Therefore, in order to apply an insulating film 130 with reduced variation to a target portion of each workpiece W, it is effective to reduce the variation between the electric flux densities for that target portion of each workpiece W and to extend the time of the electrocoating process (electrocoating time).

[0039] Here, the electric flux density related to a target portion of each workpiece W correlates with the shortest distance between the second electrode 76 and the target portion of each workpiece W. That is, the electric flux density related to a target portion of the workpiece W tends to be higher as the shortest distance becomes shorter.

[0040] Therefore, by making the variation in the shortest distance between the target portions of multiple workpieces W and the second electrode 76 among the multiple workpieces W relatively small, it is possible to reduce the variation in the thickness of the insulating film 130 applied to the target portions of each workpiece W while shortening the electrocoating time.

[0041] The allowable upper limit for the variation in the shortest distance between the target portion and the second electrode 76 among the multiple workpieces W varies depending on the required quality, and the smaller the upper limit, the more effectively the variation in the thickness of the insulating film 130 can be reduced. Therefore, the allowable upper limit is preferably about 5 mm as described above, more preferably 3 mm or less, and even more preferably 1 mm or less.

[0042] Here, when the target portions of the multiple workpieces W are within the ranges W2 and W1 in Fig. 4B, it is preferable that the second electrode 76 is located between the two slot accommodating portions 50 when viewed from a direction in which the workpieces W appear U-shaped, as shown in Fig. 5. In this case, it is possible to reduce the variation in thickness of the insulating film 130 in a relatively large portion of the portions within the ranges W2 and W1.

[0043] [Example 1] 6 and 7 are explanatory diagrams of the coil manufacturing apparatus 1 and manufacturing method according to the first embodiment, and FIG. 6 is a perspective view showing the relationship between a plurality of workpieces W immersed in an electrodeposition bath 70 and the second electrode 76A, and FIG. 7 is an enlarged view of the periphery of the workpiece W in FIG. 6. In FIG. 6 and FIG. 7 (similarly to FIG. 13 and the like below), mutually orthogonal X, Y, and Z axes are defined, and the Z axis defines the Z1 side and the Z2 side along the Z direction. The Z direction (an example of the third direction) corresponds to the up-down direction, and the Z1 side and the Z2 side correspond to the upper side and the lower side, respectively. FIG. 8 is an enlarged view of the periphery of the transition portion 54 (offset portion 521B) as viewed in the X direction (an example of the second direction), and is a diagram showing the relationship between the transition portion 54 and the second electrode 76A.

[0044] In addition, in Figures 6 and 7 (as well as subsequent Figures 13, etc.), the above-mentioned first electrode 74 and electrodeposition processing portion 78 are omitted from the illustration, but the first electrode 74 and the electrodeposition processing portion 78 are assumed to be provided in a similar manner to that shown in Figure 4A.

[0045] In the example shown in FIG. 6 and FIG. 7, a plurality of workpieces W are immersed at the same time. Specifically, a plurality of workpieces W are immersed in a manner arranged in the Y direction (an example of a first direction) as an example. In the example shown in FIG. 6 and FIG. 7, the workpieces W form a line in the Y direction, but two or more lines may be formed in a manner offset from each other in the X direction. In the following, unless otherwise specified, a line of workpieces W in the Y direction will be described, but the same may be substantially applied to other lines of workpieces W in the case of two or more lines. This is the same for the second embodiment and subsequent examples described later. In addition, the figures shown in FIG. 6 and FIG. 7 show a state in which the workpieces W are immersed in the electrodeposition tank 70 (a state in which the electrodeposition coating process is being performed). This is the same for the following FIG. 13 and the like. In addition, the positional relationship between the workpieces W and the second electrode 76A described below is the positional relationship when the electrodeposition coating process is being performed.

[0046] In the first embodiment, the second electrode 76A includes a center electrode 761A arranged along the Y direction. The center electrode 761A is arranged on the center side of the multiple workpieces W in the X direction. That is, the center electrode 761A is positioned between a pair (two) of slot accommodating portions 50 in the X direction with respect to the multiple workpieces W. At this time, the center electrode 761A is positioned so as to overlap the multiple workpieces W when viewed in the X direction. Thereby, as described above with reference to FIG. 5, the above-mentioned variation in the shortest distance between the multiple workpieces W can be effectively reduced. That is, the positional relationship of the second electrode 76A with respect to each of the multiple workpieces W becomes substantially the same, and the above-mentioned variation in the shortest distance between the multiple workpieces W can be effectively reduced.

[0047] The center electrode 761A is preferably positioned at a midpoint between the pair of slot-receiving portions 50 along the X direction. In this case, the positional relationship of the center electrode 761A with respect to the pair of slot-receiving portions 50 is substantially the same in each of the multiple workpieces W, and the variation in the thickness of the insulating film 130 applied to the pair of slot-receiving portions 50 (variation within the same workpiece) can be effectively reduced.

[0048] 7, the center electrode 761A may be formed of multiple pieces overlapping in the Y direction. In this case, the center electrode 761A may be set for each workpiece W such that one piece corresponds to one workpiece W, or may be set for multiple workpieces W such that one piece corresponds to multiple workpieces W. Alternatively, the center electrode 761A may be formed of one common piece for all workpieces W in a row.

[0049] The center electrode 761A faces the transition portions 54 of the multiple workpieces W from both sides in the Y direction. Specifically, as shown in Figs. 7 and 8, the center electrode 761A has a groove 76210 at its lower end, through which the transition portion 54 passes. The groove 76210 is formed over the entire X direction of the lower end portion of the center electrode 761A, with the groove 76210 opening downward. In this case, wall portions 76211 on both sides in the Y direction that form the groove 76210 face the transition portions 54 that pass through the groove 76210 from both sides in the Y direction.

[0050] Such a central electrode 761A can realize a relatively short distance (see shortest distance D in FIG. 8) between the transition portions 54 of the multiple workpieces W, and can effectively increase the electric flux density in the transition portions 54 (especially the offset portions 521B).

[0051] Incidentally, a bent portion such as offset portion 521B of transition portion 54 (for example, a portion bent on the flatwise side) tends to have a smaller electric flux density than a straight portion (for example, slot-receiving portion 50) even if the shortest distance is the same, and therefore paint tends to be difficult to electrodeposit thereon. Also, due to surface irregularities caused by the bent portion (the portion bent), paint tends to be difficult to electrodeposit uniformly.

[0052] In this respect, according to the present embodiment, the center electrode 761A has a groove 76210 through which the transition portion 54 is passed, so that the shortest distance D between the second electrode 76A (center electrode 761A) and the transition portion 54 can be appropriately set. For example, the shortest distance D between the second electrode 76A (center electrode 761A) and the transition portion 54 can be significantly smaller than the shortest distance (see the shortest distance L1 in FIG. 5) between the second electrode 76A (center electrode 761A) and the slot accommodating portion 50. This makes it possible to provide the insulating film 130 with a necessary thickness also on the transition portion 54. In addition, since the center electrode 761A can be brought close to the transition portion 54 from multiple directions (i.e., both sides in the Y direction and from the upper side), the thickness of the insulating film 130 provided on the transition portion 54 can be made uniform.

[0053] Fig. 9 is an explanatory diagram of an example of a suitable arrangement when performing an electrodeposition coating process by simultaneously immersing two or more rows in the Y direction (two or more rows in the Y direction along the X direction) of workpieces W in an electrodeposition bath 70. Fig. 9 shows a plurality of workpieces W forming two rows in the Y direction as viewed from above.

[0054] As shown in Fig. 9, multiple workpieces W may be immersed in the electrodeposition tank 70 in such a manner that they are separated from each other by a distance A, which is the shortest distance when viewed from above. In this case, the distance A, which is the pitch between the workpieces, may be preferably set between 1 mm and 100 mm. This makes it possible to optimize the number of workpieces W that can be immersed in the electrodeposition tank 70, while preventing inconveniences (e.g., non-uniformity of electric flux density) that may occur when the workpieces W are excessively close to each other. Note that, although three workpieces W are lined up in each of two rows in Fig. 9, the number of workpieces W can be changed as appropriate.

[0055] Next, the effects of this embodiment will be further described with reference to FIGS. 10A to 11.

[0056] 10A and 10B are explanatory diagrams of the configuration of the second electrode 76A' according to a comparative example, where Fig. 10A is a perspective view showing a schematic diagram of the relationship between the workpiece W immersed in the electrodeposition tank 70 and the second electrode 76A', and Fig. 10B is a diagram showing the analysis results for the comparative example, and is a table comparing the calculated values ​​of the thickness (film thickness) of the insulating film 130 applied to the transition portions 54 of three workpieces W arranged in the Y direction. In Fig. 10B, each calculated value is shown in a bar graph in association with the three workpieces W(1), W(2), and W(3).

[0057] In the comparative example, as shown in Fig. 10A, the second electrode 76A' is disposed on a side wall of the electrodeposition tank 70 (side walls on both sides in the Y direction in Fig. 10A). The second electrode 76A' is flat and extends in the XZ plane so as to overlap each workpiece W when viewed in the Y direction. In the comparative example, the three workpieces W lined up in the Y direction are disposed in the center between the two second electrodes 76A' in the Y direction.

[0058] In this comparative example, the variation in the shortest distance between the target portion (in this case, the transition portion 54) and the second electrode 76A' substantially corresponds to the distance between the workpieces in the Y direction. That is, of the three workpieces W lined up in the Y direction, the two workpieces W on both sides in the Y direction have approximately the same shortest distance (shortest distance to the second electrode 76A'), whereas the shortest distance of the middle workpiece W is greater by the distance between the workpieces in the Y direction than the two workpieces W on both sides in the Y direction.

[0059] The results shown in Fig. 10B were obtained when the distance between the workpieces in the Y direction was 5 mm. In Fig. 10B, reference numerals 101 and 103 indicate the calculated values ​​of the thickness of the insulating film 130 for the two workpieces W (1) and (3) on both sides in the Y direction, and reference numeral 102 indicates the calculated value of the thickness of the insulating film 130 for the single workpiece W (2) in the middle. Note that even in the transition portion 54 of the same workpiece W, the film thickness differs between the surface closer to the second electrode 76A' in the Y direction and the surface farther from it, but here the maximum film thickness is used.

[0060] As can be seen from FIG. 10B, the thickness of the insulating film 130 at the target portion (in this case, the transition portion 54) for the middle workpiece W(2) is significantly lower (e.g., by an amount significantly greater than 15 μm) than the same thickness for the two workpieces W(1), (3) on either side in the Y direction.

[0061] FIG. 11 is a diagram showing the analysis results for this embodiment, in which the upper side shows the calculated values ​​of the thickness of the insulating film 130 at each target portion of the workpiece W, and the lower side shows a diagram explaining each target portion of the workpiece W.

[0062] In FIG. 11, four target parts where the line segment LA to the line segment LD shown in the lower part of FIG. 11 intersect are evaluated. In the upper part of FIG. 11, the calculated values ​​of the thickness of the insulating film 130 are shown for each of the edgewise side (denoted as "EW side") surface (side surface in the X direction) and the flatwise side (denoted as "FW side") surface (side surface in the Y direction) of each target part. In addition, in FIG. 11, the three target parts where the line segment LA to the line segment LC intersect form the slot accommodating portion 50, and their average values ​​are plotted in the upper part of FIG. 11 as the calculated values ​​from the line segment LA to the line segment LC. In addition, in the upper part of FIG. 11, W(Ref) indicates the calculated value when a single workpiece W is analyzed as a reference value, W(2) indicates the calculated value for the middle workpiece W of the three workpieces W arranged in the Y direction, and W(1) and (3) indicate the calculated values ​​for the workpieces W on both sides in the Y direction of the three workpieces W arranged in the Y direction. Each of W(Ref) to W(3) is associated with three plots of the average film thickness, the maximum film thickness, and the minimum film thickness.

[0063] As can be seen from Fig. 11, in this embodiment, the difference (i.e., variation) between each calculated value associated with W(2) and each calculated value associated with W(1) and (3) is significantly reduced compared to the comparative example. For example, there is no variation exceeding 15 µm. From this, it can be seen from the analysis that the provision of the second electrode 76A can reduce the variation in the thickness of the insulating film 130 applied to the target portion of each workpiece W.

[0064] 12 is a diagram showing the difference in the analysis results of the calculated thickness of the insulating film 130 between the center side surface of the workpiece W and the opposite side surface of the workpiece W. At the bottom of Fig. 12, an arrow R1 indicating the center side surface of the workpiece W and an arrow R2 indicating the opposite side surface of the workpiece W are shown together with a schematic diagram of the second electrode 76A.

[0065] In this embodiment, as described above, the second electrode 76A faces only the surface (see arrow R1) on the center side and edgewise side of the workpiece W in the X direction among the four side surfaces of the slot accommodation portion 50 of the workpiece W. Therefore, the paint tends to be difficult to be electrodeposited on the surface (see arrow R2) on the opposite side to the center side of the workpiece W in the X direction (i.e., the side facing the side wall of the electrodeposition tank 70 in the X direction) among the two edgewise side surfaces of the slot accommodation portion 50 of the workpiece W. This can also be seen from the analysis results shown in FIG. 12. That is, in the example shown in the upper part of FIG. 12, the calculated value of the thickness of the insulating film 130 applied to the side surface of the workpiece W on the opposite side (R2) from the center side in the X direction is significantly lower (for example, by a reduction amount significantly larger than 15 μm) than the calculated value of the thickness of the insulating film 130 applied to the side surface of the workpiece W on the center side (R1) in the X direction.

[0066] Hereinafter, the variation (difference) in the thickness of the insulating film 130 that may occur between the center side of the workpiece W in the X direction and the opposite side at the same portion of the workpiece W will also be referred to as the "film thickness variation between the side surfaces at the target portion of the workpiece W."

[0067] 13 is an explanatory diagram of a modified example of the second electrode 76A of the present embodiment described above with reference to Fig. 7 etc., and is a perspective view showing the relationship between the second electrode 76B according to this modified example and a plurality of workpieces W. This modified example has a suitable configuration for reducing the film thickness variation between the side surfaces in the target portion of the workpiece W described above with reference to Fig. 12.

[0068] Specifically, the second electrode 76B according to this modification is different from the second electrode 76A of the present embodiment described above with reference to Fig. 7 etc. in that it includes a paired side electrode 762B. That is, the second electrode 76B according to this modification includes a center electrode 761B that is substantially the same as the center electrode 761A of the second electrode 76A of the present embodiment described above with reference to Fig. 7 etc., and a paired side electrode 762B.

[0069] The pair of side electrodes 762B are disposed on both sides in the X direction of the plurality of workpieces W immersed in the electrodeposition bath 70. That is, the pair of side electrodes 762B are positioned on both sides of the two slot accommodating portions 50 in the X direction with respect to the plurality of workpieces W immersed in the electrodeposition bath 70.

[0070] The pair of side electrodes 762B are arranged along the Y direction in a manner overlapping a plurality of workpieces W when viewed in the X direction. The pair of side electrodes 762B may be arranged along the Y direction in a manner in which one electrode corresponds to one workpiece W, as shown in FIG. 13. Alternatively, the pair of side electrodes 762B may be arranged along the Y direction in a manner in which one electrode corresponds to two or more workpieces W. For example, the pair of side electrodes 762B may each be in the form of a single piece. In the example shown in FIG. 13, the pair of side electrodes 762B has a circular cross-sectional shape (cross-sectional shape when cut on a horizontal plane) and is in the form of a rod extending in the vertical direction with an equal cross section. However, the form of the pair of side electrodes 762B is arbitrary, and may have, for example, a rectangular cross-sectional shape.

[0071] Such a pair of side electrodes 762B faces the side surface opposite to the center side in the X direction of the workpiece W, and has a function of facilitating electrodeposition of paint on the opposite side surface. This makes it possible to reduce the film thickness variation between the side surfaces in the target portion of the workpiece W described above with reference to FIG.

[0072] 14 is an explanatory diagram of various parameters related to the positional relationship (as viewed in the Y direction) between the second electrode 76B and the workpiece W according to this modified example. Note that the following various parameters represent the distance between the second electrode 76B and the workpiece W.

[0073] Parameter B is the distance (distance along the X direction) between the center electrode 761B and one of the two slot accommodating portions 50 of the workpiece W, parameter B″ is the distance between the center electrode 761B and the other of the two slot accommodating portions 50 of the workpiece W, and parameter B′ is the distance (distance along the X direction) between the lower part of the slot accommodating portion 50 of the workpiece W (the target portion closer to the crossover portion 54) and the center electrode 761B. Parameter C is the distance (distance along the X direction) between the side electrode 762B and one (the closer) of the two slot accommodating portions 50 of the workpiece W.

[0074] In this modified example, the relationship between the values ​​of the parameters B and B' is preferably such that the values ​​of the parameters B and B' are substantially the same, specifically, B:B'=0.01-1:0.01-1, more preferably B:B'=0.1-1:0.1-1, and most preferably B:B'=1:1. The relationship between the values ​​of the parameters B and B" is preferably B:B"=0.01-1:0.01-1, more preferably B:B"=0.1-1:0.1-1, and most preferably B:B"=1:1. By realizing such a relationship between the values ​​of the parameters B and B' or B", it is possible to reduce film thickness variations between different portions of the slot accommodating portion 50 in the same workpiece W.

[0075] Moreover, the relationship between the values ​​of parameters B and C is preferably such that the values ​​of parameters B and C are substantially the same, specifically, B:C=0.01-1:0.01-1, more preferably B:C=0.1-1:0.1-1, and most preferably B:C=1:1. By realizing such a relationship between the values ​​of parameters B and C, it is possible to reduce the film thickness variation between the side surfaces in the target portion of the workpiece W.

[0076] Moreover, in the relationship between the parameter B and the above-mentioned parameter D (see FIG. 8), the relationship between the respective values ​​is preferably B:D=1:0.01 to 0.99. By realizing such a relationship between the respective values ​​of the parameter B and the parameter D, it is possible to reduce the film thickness variation between the slot-accommodating portion 50 and the transition portion 54 (especially the offset portion 521B) in the same workpiece W.

[0077] 15 is an explanatory diagram of yet another modified example of the second electrode 76A of the present embodiment described above with reference to Fig. 7 etc., and is a perspective view showing the relationship between a second electrode 76C according to this modified example and a plurality of workpieces W. This modified example has a suitable configuration for reducing the film thickness variation between the side surfaces in the target portion of the workpiece W described above with reference to Fig. 12.

[0078] The second electrode 76C according to this modification is different from the second electrode 76A according to the present embodiment described above with reference to Fig. 7 etc. in that it includes a pair of side electrodes 762C and the center electrode 761A is replaced with the center electrode 761C. That is, the second electrode 76C according to this modification includes a center electrode 761C and a pair of side electrodes 762C.

[0079] The center electrode 761C has a different cross-sectional shape (cross-sectional shape when cut on a horizontal plane) from the center electrode 761A of this embodiment described above with reference to Fig. 7 etc., and has a circular cross-sectional shape in this modification. The center electrode 761C may have the same configuration around the transition portion 54 as the center electrode 761A of this embodiment described above with reference to Fig. 7 etc.

[0080] The pair of lateral electrodes 762C may be similar to the pair of lateral electrodes 762B according to the modification described above with reference to Fig. 13. This modification also provides the same effects as the modification described above with reference to Fig. 13. Note that the relationship of various parameters shown in Fig. 14 may also be realized in this modification.

[0081] Meanwhile, the various second electrodes 76A, 76B, and 76C described above may be movable up and down relative to the electrodeposition tank 70, and are preferably set in the electrodeposition tank 70 after a plurality of workpieces W are set therein during the electrodeposition coating process. However, the lateral electrodes 762B, 762C of the second electrodes 76B, 76C may be supported on the electrodeposition tank 70 side.

[0082] Figure 16 is an explanatory diagram of a modified example of the center electrode 761A of the second electrode 76A of the present embodiment described above with reference to Figure 7 etc., and is a two-sided view showing the relationship between the center electrode 761D of this modified example and multiple workpieces W.

[0083] In this modification, the center electrode 761D is disposed on the center side of the multiple workpieces W in the X direction in a manner that the lower end is supported by the bottom 702 of the electrodeposition tank 70. At this time, the center electrode 761D is positioned so as to be close to the multiple workpieces W in the Y direction. In the example shown in FIG. 16, the center electrode 761D is disposed in a manner that a pair (two pairs) is formed for each workpiece W, sandwiching the transition portion 54 in the Y direction while being slightly offset in the X direction. In this case, the positional relationship of the center electrode 761D with respect to each of the multiple workpieces W is approximately the same, and the above-mentioned variation in the shortest distance between the multiple workpieces W can be effectively reduced. Also, in this case, the center electrode 761D can face the transition portion 54 of the multiple workpieces W from both sides in the Y direction in the Y direction. This makes it possible to effectively increase the electric flux density related to the transition portion 54 in the electrodeposition coating process. The separation distance between the center electrode 761D and the transition portion 54 may be the same as the above-mentioned shortest distance D (parameter D).

[0084] In this modified example as well, the center electrode 761D is preferably positioned at a midpoint between the pair of slot-accommodating portions 50 along the X direction. In this case, the positional relationship of the center electrode 761D with respect to the pair of slot-accommodating portions 50 is substantially the same in each of the multiple workpieces W, and the variation in the thickness of the insulating film 130 applied to the pair of slot-accommodating portions 50 (variation within the same workpiece) can be effectively reduced.

[0085] The center electrode 761D shown in FIG. 16 may be realized in combination with the side electrodes 762B and 762C described above.

[0086] Figure 17 is an explanatory diagram of another modified example of the center electrode 761A of the second electrode 76A of the present embodiment described above with reference to Figure 7 etc., and is a two-sided view showing the relationship between the center electrode 761E of this modified example and multiple workpieces W.

[0087] In this modification, the center electrode 761E is disposed on the center side of the multiple workpieces W in the X direction, with the lower end supported by the bottom 702 of the electrodeposition tank 70. At this time, the center electrode 761E is positioned between the multiple workpieces W in the Y direction. In the example shown in FIG. 17, the center electrode 761E has a flat plate shape and extends in the vertical direction between the multiple workpieces W in the Y direction. In this case, the positional relationship of the center electrode 761E with respect to each of the multiple workpieces W is approximately the same, and the above-mentioned variation in the shortest distance between the multiple workpieces W can be effectively reduced. In addition, in this case, the center electrode 761E can face the transfer portion 54 of the multiple workpieces W from both sides in the Y direction in the Y direction. This makes it possible to effectively increase the electric flux density related to the transfer portion 54 in the electrodeposition coating process. The separation distance between the center electrode 761E and the transfer portion 54 may be the same as the above-mentioned shortest distance D (parameter D).

[0088] In this modification, the center electrode 761E is preferably positioned at a midpoint between the pair of slot-accommodating portions 50 along the X direction. In this case, the positional relationship of the center electrode 761E with respect to the pair of slot-accommodating portions 50 is substantially the same in each of the multiple workpieces W, and the variation in the thickness of the insulating film 130 applied to the pair of slot-accommodating portions 50 (variation within the same workpiece) can be effectively reduced.

[0089] The center electrode 761E shown in FIG. 17 may be realized in combination with the side electrodes 762B and 762C described above.

[0090] Figure 18 is an explanatory diagram of yet another modified example of the center electrode 761A of the second electrode 76A of the present embodiment described above with reference to Figure 7 etc., and is a two-sided view showing the relationship between the center electrode 761F of this modified example and multiple workpieces W.

[0091] In this modification, the center electrode 761F is disposed on the center side of the multiple workpieces W in the X direction in a manner that the lower end is supported by the bottom 702 of the electrodeposition tank 70. At this time, the center electrode 761F is positioned between the multiple workpieces W in the Y direction. In this case, the positional relationship of the center electrode 761F with respect to each of the multiple workpieces W is approximately the same, and the above-mentioned variation in the shortest distance between the multiple workpieces W can be effectively reduced. In the example shown in FIG. 18, the center electrode 761F has a flat plate shape, but unlike the center electrode 761E shown in FIG. 17, the cross-sectional shape differs depending on the position in the vertical direction. Specifically, the center electrode 761F has a relatively large dimension in the X direction in a section (vertical section) facing the crossover portion 54 of the multiple workpieces W as viewed in the Y direction. In this case, the center electrode 761F can efficiently increase the electrode area facing the crossover portion 54 while facing the crossover portion 54 of the multiple workpieces W from both sides in the Y direction. This effectively increases the electric flux density in the transition portion 54 (particularly the offset portion 521B) during the electrocoating process. The distance between the center electrode 761F and the transition portion 54 may be the same as the shortest distance D (parameter D) described above.

[0092] In this modified example as well, the center electrode 761F is preferably positioned at a midpoint between the pair of slot-accommodating portions 50 along the X direction. In this case, the positional relationship of the center electrode 761F with respect to the pair of slot-accommodating portions 50 is substantially the same in each of the multiple workpieces W, and the variation in the thickness of the insulating film 130 applied to the pair of slot-accommodating portions 50 (variation within the same workpiece) can be effectively reduced.

[0093] The center electrode 761F shown in FIG. 18 may be realized in combination with the side electrodes 762B and 762C described above.

[0094] [Example 2] Next, a second electrode configuration according to the second embodiment will be described with reference to FIG. 19 and subsequent figures.

[0095] Incidentally, the workpiece W is provided with the insulating film 130 to finally form the coil pieces 52, and in the portion (crossover portion 54) forming the coil ends, it is preferable that the insulating film 130 be relatively thick in the coil pieces 52 from the viewpoint of improving insulation between different phases. On the other hand, in the slot-receiving portion 50 of the coil pieces 52 received in the slot 23, it is preferable that the insulating film 130 be relatively thin in the slot-receiving portion 50 from the viewpoint of increasing the occupancy rate of the conductor in the slot 23.

[0096] Therefore, the second electrode configuration according to this embodiment is configured so that the thickness of the insulating film 130 applied to the transition portion 54 of the workpiece W is significantly larger than the thickness of the insulating film 130 applied to the slot-accommodating portion 50. In this case, when the thickness of the insulating film 130 applied to the slot-accommodating portion 50 is 1.0, the thickness of the insulating film 130 applied to the transition portion 54 is 1.1 or more, and preferably 2.0 (i.e., twice as large) or more. Note that the boundary position between the range where the insulating film 130 has a relatively large thickness and the range where the insulating film 130 has a relatively small thickness does not need to strictly match the boundary position between the transition portion 54 and the slot-accommodating portion 50, and may be slightly shifted from the boundary position between the transition portion 54 and the slot-accommodating portion 50. For example, the thickness of the insulating film 130 applied to the lower portion of the slot-accommodating portion 50 may be relatively large, similar to the thickness of the insulating film 130 applied to the transition portion 54.

[0097] 19 is a perspective view showing the relationship between the second electrode 76G of this embodiment and a plurality of workpieces W. This embodiment differs from the second electrode 76A of the above-described first embodiment mainly in the shape (configuration of the lower end) of the center electrode 761G. The arrangement of the center electrode 761G may be similar to the arrangement of the center electrode 761A of the above-described first embodiment.

[0098] Specifically, the center electrode 761G of this embodiment has a base portion 7614G and a thick film forming portion 7616G.

[0099] The base portion 7614G may have substantially the same configuration as the center electrode 761A according to the first embodiment described above, except for the lower end portion. Specifically, the base portion 7614G is disposed on the center side in the X direction of the multiple workpieces W. That is, the base portion 7614G is positioned between a pair (two) of slot accommodating portions 50 in the X direction with respect to the multiple workpieces W. At this time, the base portion 7614G is positioned so as to overlap the multiple workpieces W as viewed in the X direction. Thereby, as described above with reference to FIG. 5, the variation in the shortest distance between the multiple workpieces W described above can be effectively reduced.

[0100] The base portion 7614G is preferably positioned at a midpoint between the pair of slot-accommodating portions 50 along the X direction. In this case, the positional relationship of the base portion 7614G with respect to the pair of slot-accommodating portions 50 is approximately the same in each of the multiple works W, and the variation in the thickness of the insulating film 130 applied to the pair of slot-accommodating portions 50 (variation within the same work) can be effectively reduced.

[0101] The thick film forming portion 7616G continues downward from the lower end of the base portion 7614G. The thick film forming portion 7616G overlaps the transition portions 54 of the multiple workpieces W when viewed in the vertical direction. The thick film forming portion 7616G preferably overlaps substantially the entire X-direction of the transition portions 54 of the multiple workpieces W when viewed in the vertical direction. The substantially entire X-direction of the transition portions 54 takes into consideration the X-direction gap (see parameter B' described later) secured between the workpieces W and the thick film forming portion 7616G at both ends in the X-direction. Therefore, the thick film forming portion 7616G preferably has a significantly larger dimension in the X-direction than the base portion 7614G.

[0102] FIG. 20 is a diagram showing the analysis results for this embodiment, and the target parts to be evaluated are as shown in the lower part of FIG. 11 described above. Among the three target parts where the line segment LA and the line segment LC intersect as shown in FIG. 11, the target parts of the upper line segment LA and the line segment LB do not overlap the thick film forming part 7616G when viewed in the X direction. On the other hand, the target part of the line segment LC overlaps the thick film forming part 7616G when viewed in the X direction. In FIG. 20, among the three target parts where the line segment LA and the line segment LC intersect, the average values ​​of the target parts of the upper line segment LA and the line segment LB are plotted as the calculated values ​​of the line segment LA and the line segment LB. In addition, the average values ​​of the target parts of the line segment LC and the line segment LD are plotted as the calculated values ​​of the line segment LC and the line segment LD. 20, W(Ref) indicates the calculated value when analyzing a single workpiece as a reference value, W(2) indicates the calculated value for the middle workpiece W of three workpieces lined up in the Y direction, and W(1) and (3) indicate the calculated values ​​for the workpieces W on both sides in the Y direction of the three workpieces lined up in the Y direction. Each of W(Ref) to W(3) is associated with three plots of the average film thickness, the maximum film thickness, and the minimum film thickness.

[0103] As can be seen from Fig. 20, in this embodiment, the difference (i.e., the variation) between each calculated value associated with W(2) and each calculated value associated with W(1) and (3) is significantly reduced compared to the comparative example. For example, there is no variation exceeding 15 µm. From this, it can be seen from the analysis that the provision of the second electrode 76G can reduce the variation in the thickness of the insulating film 130 applied to the target portion of each workpiece W.

[0104] 20, in this embodiment, by providing the thick film forming portion 7616G, it is possible to effectively increase the thickness of the insulating film 130 applied to the target portion (the target portion of the line segment LC and the line segment LD) that is the shortest distance from the thick film forming portion 7616G. That is, from FIG. 20, the target portion (the target portion of the line segment LC and the line segment LD) that is the shortest distance from the thick film forming portion 7616G among the target portions of the workpiece W has a larger thickness of the insulating film 130 than the other target portions, that is, the target portion (the target portion of the line segment LA and the line segment LB) that is the shortest distance from the base portion 7614G.

[0105] 21 is an explanatory diagram of a modified example of the second electrode 76G of the present embodiment described above with reference to Fig. 7 etc., and is a perspective view showing the relationship between the second electrode 76H according to this modified example and a plurality of workpieces W. This modified example has a suitable configuration for reducing the film thickness variation between the side surfaces in the target portion of the workpiece W described above with reference to Fig. 12.

[0106] Specifically, the second electrode 76H according to this modification is different from the second electrode 76G of the present embodiment described above with reference to FIG. 7 and the like in that it includes a pair of side electrodes 762H. That is, the second electrode 76H according to this modification includes a center electrode 761H that is substantially the same as the center electrode 761G of the second electrode 76G of the present embodiment described above with reference to FIG. 19, and a pair of side electrodes 762H. The pair of side electrodes 762H may have the same configuration as the pair of side electrodes 762B described above with reference to FIG. 13. In this case, it is possible to reduce the film thickness variation between the side surfaces in the target portion of the workpiece W described above with reference to FIG. 12.

[0107] FIG. 22 is an explanatory diagram of various parameters relating to the positional relationship (the positional relationship when viewed in the Y direction) between the second electrode 76H and the workpiece W according to this modified example shown in FIG.

[0108] In FIG. 22, parameters B, B'', and C associated with the base portion 7614H may be similar to parameters B, B'', and C described above with reference to FIG. 14 in relation to the first embodiment.

[0109] Parameter B' is the distance (the distance along the X direction) between the thick film formation portion 7616H and the two slot accommodating portions 50 of the workpiece W, and parameter C' is the distance (the distance along the X direction) between the lateral electrode 762H and a portion of one (the closer) of the two slot accommodating portions 50 of the workpiece W that overlaps with the thick film formation portion 7616H when viewed in the X direction.

[0110] In this modification, the relationship between the values ​​of the parameters B and B' is preferably B:B'=1:0.99-0.01, more preferably B:B'=1:0.5-0.01, and even more preferably B:B'=1:0.2-0.01. The relationship between the values ​​of the parameters B and C is preferably B:C=1:0.01-2. The relationship between the values ​​of the parameters C and C' is preferably C:C'=1:0.99-0.01, more preferably C:C'=1:0.5-0.01, and even more preferably C:C'=1:0.2-0.01. The relationship between the values ​​of the parameters B' and C' is preferably B':C'=1:1-0.01. 22, the lower part of the side electrode 762H is offset toward the slot-accommodating portion 50 so that C:C'=1:0.2 to 0.01. In this manner, the lower part of the side electrode 762H may be offset toward the slot-accommodating portion 50 relative to the upper part.

[0111] By realizing such a relationship between the values ​​of parameters B', C', etc., it is possible to reduce the film thickness variation between the slot-receiving portion 50 and the transition portion 54 within the same workpiece W.

[0112] 23 is an explanatory diagram of a further modified example of the second electrode 76G of the present embodiment described above with reference to Fig. 19, and is a perspective view showing the relationship between the second electrode 76I according to this modified example and a plurality of workpieces W. This modified example has a suitable configuration for reducing the film thickness variation between the side surfaces in the target portion of the workpiece W described above with reference to Fig. 12.

[0113] The second electrode 76I according to this modification is different from the second electrode 76G according to the present embodiment described above with reference to Fig. 19 in that it includes a pair of side electrodes 762I and the center electrode 761G is replaced with a center electrode 761I. That is, the second electrode 76I according to this modification includes a center electrode 761I and a pair of side electrodes 762I.

[0114] The center electrode 761I is different from the center electrode 761G of the present embodiment described above with reference to FIG. 19 in that it is divided in the Y direction, and in this modified example, it is divided so that there is one for each workpiece W. The center electrode 761I is also different in that the dimension in the X direction of the base portion 7614I is smaller than that of the base portion 7614G of the center electrode 761G of the present embodiment described above, but the dimension in the X direction may be the same as that of the base portion 7614G of the present embodiment described above. The center electrode 761I is also different from the thick film forming portion 7616G of the center electrode 761G of the present embodiment described above in that the dimension in the vertical direction of the thick film forming portion 7616I is smaller than that of the thick film forming portion 7616G of the present embodiment described above, but the dimension in the vertical direction may be the same as that of the thick film forming portion 7616G of the present embodiment described above.

[0115] The pair of lateral electrodes 762I may be similar to the pair of lateral electrodes 762H according to the modification described above with reference to Fig. 21. This modification also provides the same effects as the modification described above with reference to Fig. 21. Note that this modification also may achieve the relationship of various parameters shown in Fig. 22 (positional relationship when viewed in the Y direction).

[0116] Meanwhile, the various second electrodes 76G, 76H, and 76I described above may be movable in the vertical direction relative to the electrodeposition tank 70, and are preferably set in the electrodeposition tank 70 after a plurality of workpieces W are set therein during the electrodeposition coating process. However, the lateral electrodes 762H, 762I of the second electrodes 76H, 76I may be supported on the electrodeposition tank 70 side.

[0117] Figure 24 is an explanatory diagram of a further modified example of the center electrode 761G of the second electrode 76G of the present embodiment described above with reference to Figure 19, and is a front view showing the relationship between the center electrode 761J of this modified example and multiple workpieces W.

[0118] In this modification, the center electrode 761J forming the second electrode 76J is disposed on the center side in the X direction of the multiple workpieces W with its lower end supported by the bottom 702 of the electrodeposition tank 70. The center electrode 761J is divided so that there is one for each workpiece W, similar to the center electrode 761I described above with reference to FIG. 23. In this case, the center electrode 761J is positioned between the multiple workpieces W in the Y direction so as to be close to the multiple workpieces W in the Y direction. In this case, the positional relationship of the center electrode 761J with respect to each of the multiple workpieces W is approximately the same, and the above-mentioned variation in the shortest distance between the multiple workpieces W can be effectively reduced.

[0119] In this modification, the base portion 7614J of the center electrode 761J is preferably positioned at a middle position between the pair of slot-receiving portions 50 along the X direction. In this case, the positional relationship of the center electrode 761J with respect to the pair of slot-receiving portions 50 is substantially the same in each of the plurality of workpieces W, and the variation in the film thickness of the insulating film 130 applied to the pair of slot-receiving portions 50 (variation within the same workpiece) can be effectively reduced. In the example shown in FIG. 24, the thick film forming portion 7616J of the center electrode 761J is arranged in such a manner that a pair (two pairs) sandwiching the transition portion 54 in the Y direction is formed for each workpiece W. In this case, the center electrode 761J can face the transition portions 54 of the plurality of workpieces W from both sides in the Y direction in the Y direction. This makes it possible to effectively increase the electric flux density related to the transition portion 54 in the electrocoating process. The separation distance between the center electrode 761J and the transition portion 54 may be the same as the shortest distance D (parameters B', C') described above.

[0120] In this modification, the center electrode 761J has a portion 7618J extending in the vertical direction from both ends of the thick film forming portion 7616J in the X direction. The portion 7618J is arranged in such a manner that a pair (two pairs) sandwiching the lower portion of the slot-accommodating portion 50 in the Y direction is formed for each workpiece W. The portion 7618J overlaps the lower portion of the slot-accommodating portion 50 when viewed in the Y direction. In this case, the center electrode 761J can face the lower portions of the slot-accommodating portions 50 of the multiple workpieces W in the Y direction from both sides in the Y direction. This makes it possible to effectively increase the electric flux density related to the lower portion of the slot-accommodating portion 50 in the electrocoating process, and to increase the thickness of the insulating film 130 applied to the lower portion of the slot-accommodating portion 50. The separation distance between the center electrode 761J and the lower portion of the slot-accommodating portion 50 may be the same as the shortest distance D (parameters B', C') described above.

[0121] The center electrode 761J shown in FIG. 24 may be realized in combination with the side electrodes 762H and 762I described above.

[0122] 24, the portion 7618J of the center electrode 761J only overlaps the lower portion of the slot-receiving portion 50 when viewed in the Y direction, but may extend further upward to overlap substantially the entire slot-receiving portion 50. Alternatively, conversely, as in the center electrode 761K shown in FIG. 25, the portion 7618J overlapping the lower portion of the slot-receiving portion 50 when viewed in the Y direction may be omitted. In this case, the center electrode 761K forming the second electrode 76K has a base portion 7614K and a thick film forming portion 7616K. The thick film forming portion 7616K does not overlap the lower portion of the slot-receiving portion 50 when viewed in the Y direction.

[0123] Although each embodiment has been described above in detail, it is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of the components of the above-mentioned embodiments. Furthermore, among the effects of each embodiment, the effects related to the dependent claims are additional effects that are distinguished from the generic concept (independent claim).

[0124] For example, in each of the above-mentioned embodiments, the center electrodes 761A to 761K are provided, but the same effect may be achieved without using center electrodes such as the center electrodes 761A to 761K. For example, the second electrode 76L according to the modified example shown in FIG. 26 is provided in pairs on both sides in the X direction, and each has a side electrode portion 762L. The side electrode portion 762L includes a portion 7620L extending to the side of the slot receiving portion 50 and a portion 7621L extending below the transition portion 54. The portion 7620L may have the same function as the above-mentioned side electrodes 762H, 762I, etc. The portion 7621L overlaps the transition portion 54 when viewed in the up-down direction, and is the portion of the second electrode 76L that has the shortest distance to the transition portion 54. In this case, as in each of the above-mentioned embodiments, the second electrode 76L can be configured so that the positional relationship with the multiple workpieces W is approximately the same. The shortest distance between the portion 7621L and the transition portion 54 may be set in a manner similar to the value of the parameter D (see FIG. 8) described above. The same applies to other parameters (e.g., parameter B, etc.). With such a modified example, it is possible to obtain the same effect as the above-described embodiment. In the perspective view shown in FIG. 26, the portion 7620L on the near side is shown in perspective so that the state of the workpiece W, etc. can be easily understood. [Explanation of symbols]

[0125] 1...coil manufacturing apparatus, 70...electrodeposition tank, 73...electrode portion, 74...first electrode, 76, 76A to 76L...second electrode, 761A to 761K...center electrode, 762B, 762C, 762H, 762I...side electrode, 78...electrodeposition processing portion, 130...insulating film, 52, 52'...coil piece (coil), 112...stator core, 114...stator coil (coil), 7614G...base portion (second electrode portion), 7616G, 7616H...thick film forming portion (first electrode portion), 50...slot receiving portion, 54...transfer portion (coil end portion), 521B...offset portion (bending portion), W...work (coil material)

Claims

1. A method for manufacturing a coil having an insulating film, comprising the steps of: a preparation step of preparing a plurality of coil materials before the insulating film is applied; an electrodeposition coating process in which a potential difference is generated between a first electrode connected to the coil materials and a second electrode in the electrodeposition tank while the coil materials are immersed in the electrodeposition tank; In the electrocoating step, the coil materials and the second electrode are positioned relative to each other such that, for at least one target portion at the same position in the coil materials, the shortest distance between the target portion and the second electrode among the coil materials is substantially the same; The coil materials are for a stator coil to be wound around a stator core, and each of the coil materials includes two slot-receiving portions that are received in slots of the stator core in a wound state, and a coil end portion that is exposed from an axial end face of the stator core in a wound state; the target portion includes at least a part of the slot accommodation portion and the coil end portion, In the electrocoating step, the coil blanks are immersed in the electrocoating bath in a row in the first direction with the two slot-accommodating portions and the coil end portions oriented in a U-shape when viewed in the first direction, the second electrode includes a center electrode arranged along the first direction, A coil manufacturing method, in which, in the electrocoating process, the center electrode is positioned between two of the slot accommodating portions in a second direction intersecting the first direction, with respect to the plurality of coil materials immersed in the electrocoating tank, so as to overlap the plurality of coil materials when viewed in the second direction.

2. 2. The coil manufacturing method according to claim 1, wherein in the electrocoating step, the coil blanks and the second electrode are positioned relative to each other such that the variation in the shortest distance is less than 5 mm.

3. The coil manufacturing method according to claim 1 , wherein in the electrocoating step, the center electrode is positioned at a middle position between the two slot-receiving portions along the second direction.

4. the coil end portion has a bent portion that is offset in a direction corresponding to a radial direction of the stator core when the coil is wound, the target portion includes at least a part of the slot accommodation portion and the bent portion, The coil manufacturing method according to claim 1 , wherein in the electrocoating process, the shortest distance between the bent portion and the second electrode is smaller than the shortest distance between the target portion in the slot accommodating portion and the second electrode.

5. 5. The coil manufacturing method according to claim 4, wherein in the electrocoating process, the center electrode faces the bent portions of the plurality of coil blanks immersed in the electrocoating bath from both sides in the first direction.

6. In the electrocoating step, the center electrode is applied to the coil blanks immersed in the electrocoating bath. a first electrode portion overlapping the coil end portions of the plurality of coil elements when viewed in a third direction perpendicular to both the first direction and the second direction; a second electrode portion overlapping the slot-accommodated portion of each of the coil elements when viewed in the second direction; The coil manufacturing method according to claim 1, wherein in the electrocoating process, the first electrode portion is closer to the coil end portion in the third direction than the second electrode portion, and has a larger dimension in the second direction than the second electrode portion.

7. the second electrode further includes a pair of lateral electrodes arranged along the first direction; The coil manufacturing method according to claim 1, wherein in the electrocoating process, the pair of side electrodes are positioned on both sides of the two slot accommodating portions in the second direction with respect to the plurality of coil materials immersed in the electrocoating bath.

8. The coil manufacturing method described in claim 7, wherein in the electrocoating process, a distance between the pair of side electrodes and the two slot accommodating portions along the second direction is approximately equal to a distance between the center electrode and the two slot accommodating portions along the second direction.

9. An apparatus for manufacturing a coil having an insulating film, the apparatus comprising: a plurality of coil materials for a stator coil, the coil materials having two slot receiving portions that are received in slots of a stator core when wound; and coil end portions that are exposed from an axial end face of the stator core when wound; and a coil material having an insulating film applied thereto, an electrodeposition bath in which a plurality of coil materials are immersed in a row in the first direction before the insulating film is applied, with the two slot-accommodating portions and the coil end portions oriented in a U-shape when viewed in the first direction; an electrode portion that forms a first electrode connected to the plurality of coil materials and a second electrode in the electrodeposition bath while the plurality of coil materials are immersed in the electrodeposition bath; an electrodeposition processing unit that generates a potential difference between the first electrode and the second electrode, the second electrode is configured such that, with the plurality of coil materials being immersed in the electrodeposition bath, a shortest distance between the target portion and the second electrode among at least one target portion at the same position in the plurality of coil materials is substantially the same among the plurality of coil materials; the target portion includes at least a part of the slot accommodation portion and the coil end portion, the second electrode includes a center electrode arranged along the first direction, A coil manufacturing apparatus, wherein the center electrode is positioned between two of the slot accommodating portions in a second direction intersecting the first direction, with respect to the plurality of coil materials immersed in the electrochemical deposition bath, so as to overlap the plurality of coil materials when viewed in the second direction.

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