Rotor manufacturing method and rotor

Abstract

A rotor manufacturing method includes: a core plate forming step of punching a steel plate to form a plurality of core plates having a plurality of insertion holes penetrating the steel plate in a thickness direction and respectively constituting a part of the plurality of magnet insertion holes, and a plurality of protruding portions protruding toward the inside of the plurality of insertion holes; a protrusion removal step for removing at least one of the plurality of protrusions from at least a portion of the plurality of core plates formed in the core plate forming step; a lamination step in which the plurality of core plates are laminated such that the magnet insertion holes are constituted by the insertion holes from which the protruding portions protrude toward the inside and the insertion holes from which the protruding portions have been removed; and a magnet insertion step of inserting the magnet into each of the plurality of magnet insertion holes and holding the magnet by bringing the magnet into contact with the protruding portion.

Description

TECHNICAL FIELD

[0001] The present application relates to a rotor manufacturing method and a rotor. BACKGROUND

[0002] A rotor manufacturing method is known in which a magnet is inserted into a magnet insertion hole and the magnet is held by bringing a portion of a core plate into contact with the magnet. For example, Patent Document 1 discloses a manufacturing method of a core of a rotary electric machine, in which a plurality of core plates in which insertion holes are formed are laminated together, and a permanent magnet is inserted into the insertion holes, in which a bridge portion between an outer peripheral portion of the core plate and an inner side edge of the insertion hole is deformed toward the permanent magnet side, and the permanent magnet is pressed by the bridge portion. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0003] Patent Document 1: Japanese Laid-Open Patent Publication No. 2013-126330 SUMMARY PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In the manufacturing method of the above-described Patent Document 1, the permanent magnet is inserted into the insertion hole of the laminated core plates, and then a portion of the core plate located outside the periphery of the insertion hole is moved toward the permanent magnet side, thereby fixing the permanent magnet in the insertion hole. That is, in the structure of the above-described Patent Document 1, in addition to the process of inserting the magnet into the magnet insertion hole, a process of fixing the magnet in the magnet insertion hole is also required.

[0005] Therefore, there is a need for a manufacturing method of a rotor in which a magnet inserted into a magnet insertion hole is held by a portion of a core plate, which can be manufactured efficiently.

[0006] An object of the present application is to provide a manufacturing method of a rotor in which a magnet inserted into a magnet insertion hole is held by a portion of a core plate, which can be manufactured efficiently. TECHNICAL SOLUTION

[0007] The rotor manufacturing method of one embodiment of the present application is a rotor manufacturing method of a rotor including a cylindrical rotor core having a plurality of core plates laminated in a thickness direction and a plurality of magnet insertion holes extending in an axis direction, and a plurality of magnets each inserted into the plurality of magnet insertion holes. The rotor manufacturing method includes a core plate forming step of punching a steel sheet to form a plurality of core plates each having a plurality of insertion holes penetrating the steel sheet in the thickness direction and each forming part of the plurality of magnet insertion holes, and a plurality of protrusions protruding toward the inside of the plurality of insertion holes; a protrusion removing step of removing at least one of the plurality of protrusions from at least some of the plurality of core plates formed in the core plate forming step; a lamination step of laminating the plurality of core plates so that the insertion holes from which the protrusions protrude and the insertion holes from which the protrusions are removed form the magnet insertion holes; and a magnet inserting step of inserting the magnets into each of the plurality of magnet insertion holes and holding the magnets in contact with the protrusions.

[0008] The rotor of one embodiment of the present application includes a cylindrical rotor core having a plurality of core plates laminated in a thickness direction and a magnet insertion hole extending in an axis direction, and a magnet inserted into the magnet insertion hole. The plurality of core plates include a first core plate and a second core plate laminated in the thickness direction with respect to the first core plate. The first core plate has a first insertion hole penetrating the first core plate in the thickness direction and forming part of the magnet insertion hole, and a protrusion protruding toward the inside of the first insertion hole and in contact with the magnet. The second core plate has a second insertion hole penetrating the second core plate in the thickness direction and forming part of the magnet insertion hole, and a recess on an inner surface forming the second insertion hole and recessed in a direction opposite to a protruding direction of the protrusion of the first core plate when the rotor core is viewed in the axis direction. A connection portion between an inner surface forming the recess and an inner surface forming a portion other than the recess of the second insertion hole is an angle. Effect of Invention

[0009] According to one embodiment of the present application, a rotor manufacturing method in which a magnet inserted into a magnet insertion hole is held by a portion of a core plate can be efficiently manufactured. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 FIG. 1 is a cross-sectional view of the outline structure of a motor of a first embodiment. Figure 2 FIG. 2 is a perspective view of a rotor of the first embodiment. Figure 3This is a diagram showing the rotor as viewed from the axial direction. Figure 4 It is along Figure 3 A cross-sectional view along line IV-IV. Figure 5 This is a diagram showing the first core board of the first embodiment viewed from the axial direction. Figure 6 This is an enlarged view of the protrusion of the first core plate in the first embodiment. Figure 7 This is an enlarged view of the recessed part of the second core board. Figure 8 This is a flowchart illustrating the manufacturing method of the rotor according to the first embodiment. Figure 9A This diagram illustrates the process of forming an insertion hole by punching a steel plate. Figure 9B This is a diagram illustrating the area where the steel plate is punched during the protrusion removal process. Figure 9C This diagram illustrates the process of forming a recess by punching a steel sheet. Figure 10 This is a cross-sectional view of the rotor according to the second embodiment. Figure 11 This is a diagram showing the first core board of the second embodiment viewed from the axial direction. Figure 12 This is an enlarged view of the protrusions and deformation-allowing portions of the first core plate in the second embodiment. Figure 13 This is a flowchart illustrating the manufacturing method of the rotor according to the second embodiment. Figure 14 This diagram illustrates the process of forming the core board. Figure 15 This is a cross-sectional view of the rotor according to the third embodiment. Figure 16 This is a diagram showing the third core board viewed from the axial direction. Figure 17 This diagram illustrates the function of the third deformation allowance section. Figure 18 This diagram illustrates the process of forming the core board. Figure 19 This is a perspective view of the rotor according to the fourth embodiment. Figure 20 This is a cross-sectional view of the rotor according to the fourth embodiment. Figure 21 This is a diagram illustrating the structure of a rotor with multiple rotor blocks. Detailed Implementation

[0011] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Furthermore, the same or corresponding parts in the drawings are represented by the same symbols, and their descriptions will not be repeated. Additionally, the dimensions of the constituent parts in the drawings do not faithfully represent the actual dimensions of the constituent parts or the dimensional proportions of each constituent part.

[0012] In the following description of motor 1, the direction parallel to the central axis P of rotor 2 is called the axial direction, the direction perpendicular to the central axis P is called the radial direction, and the direction along the arc centered on the central axis P is called the circumferential direction.

[0013] In the following description, the direction in which the magnet 22 moves when it is inserted into the magnet insertion hole 26 during the manufacture of rotor 2 is referred to as the magnet insertion direction. Additionally, the hollow arrows in the figures indicate the magnet insertion direction. The magnet insertion direction described above is the same as the axial direction described above. However, these definitions are not intended to limit the orientation of rotor 2 during manufacture and use.

[0014] Furthermore, in the following explanation, terms such as "fixed," "connected," and "installed" include not only cases where components are directly fixed to each other, but also cases where they are fixed via other components. That is, in the following explanation, terms such as "fixed" include the meaning of components being directly or indirectly fixed to each other.

[0015] (First Implementation) (Structure of a motor) refer to Figures 1 to 7 A motor 1 having an exemplary rotor 2 according to the first embodiment will be described.

[0016] like Figure 1 As shown, the motor 1 includes a rotor 2, a stator 3, a housing 4, and a shaft 5. The rotor 2 rotates relative to the stator 3 about a central axis P. In this embodiment, the motor 1 is a so-called internal rotor type motor, wherein the rotor 2 is located inside the cylindrical stator 3 and can rotate about the central axis P.

[0017] The rotor 2 has a rotor core 21 and a magnet 22. The rotor 2 is located radially inside the stator 3 and can rotate relative to the stator 3 about the central axis P.

[0018] The rotor 2 has a shaft insertion hole 2a extending along the central axis P. The shaft 5 is fixed to the rotor 2 with its shaft insertion hole 2a passing through it in the axial direction. This allows the rotor 2 to rotate together with the shaft 5.

[0019] The stator 3 is housed within the housing 4. In this embodiment, the stator 3 is cylindrical. The rotor 2 is located radially inside the stator 3. That is, the stator 3 is located radially opposite to the rotor 2.

[0020] The stator 3 has a stator core 31 and a stator coil 32. The stator coil 32 is wound around the stator core 31. The stator 3 has a known stator structure, and thus a detailed description of the structure is omitted.

[0021] (Structure of rotor) As shown in Figure 2 , the rotor 2 has a columnar shape extending along the center axis P. The rotor 2 has a rotor core 21 and a plurality of magnets 22.

[0022] The rotor core 21 has an end surface 21a on one side in the axial direction and an end surface 21b on the other side in the axial direction. The rotor core 21 has a plurality of core plates 25 and a plurality of magnet insertion holes 26.

[0023] The plurality of core plates 25 are each a disc-shaped electromagnetic steel plate formed into a prescribed shape. The plurality of core plates 25 are stacked in the thickness direction. In the present embodiment, the plurality of core plates 25 include a plurality of first core plates 6 and a plurality of second core plates 7.

[0024] As shown in Figure 3 , the plurality of magnet insertion holes 26 have an elongated shape in one direction when the rotor core 21 is viewed in the axial direction of the rotor core 21. As shown in Figure 4 , the plurality of magnet insertion holes 26 penetrate the rotor core 21 in the above-described axial direction.

[0025] As shown in Figure 3 , the plurality of magnet insertion holes 26 are provided at prescribed intervals in the circumferential direction of the rotor core 21. The plurality of magnet insertion holes 26 include magnet insertion holes 26 whose length direction, when viewed in the above-described axial direction, follows the outer periphery of the rotor core 21, and magnet insertion holes 26 that, when viewed in the above-described axial direction, extend from the radially outer periphery side to the radially inner periphery side of the rotor core 21. The magnets 22 are inserted into the magnet insertion holes 26. The plurality of magnet insertion holes can include magnet insertion holes that, when viewed in the above-described axial direction, extend in the radial direction of the rotor core.

[0026] The magnets 22 have a cuboid shape. The magnets 22 are inserted into the magnet insertion holes 26 from the end surface 21a side of the rotor core 21. The magnets 22 are fixed to the magnet insertion holes 26 by the protruding portions 62 of the first core plates 6 described later. Hereinafter, the direction in which the magnets 22 are inserted into the magnet insertion holes 26 is referred to as the magnet insertion direction. The end surface 21a of the rotor core 21 in the axial direction is an end surface on the rear side in the magnet insertion direction. The end surface 21b of the rotor core 21 in the axial direction is an end surface on the front side in the magnet insertion direction. In the drawings, the magnet insertion direction is indicated by a hollow arrow.

[0027] As shown in Figure 4 , the plurality of core plates 25 include the first core plates 6 and the second core plates 7.

[0028] Referring to Figure 5 andFigure 6 The first core plate 6 has a plurality of first insertion holes 61 and a plurality of protrusions 62. As shown in Figure 5 In the present embodiment, the first core plate 6 has two protrusions 62 radially inside one first insertion hole 61.

[0029] The first insertion hole 61 penetrates the first core plate 6 in the thickness direction. The first insertion hole 61 constitutes a part of the magnet insertion hole 26. As shown in Figure 6 When the first core plate 6 is viewed from the above-mentioned axial direction, the first insertion hole 61 has an elongated shape in one direction. The magnet 22 is located inside the first insertion hole 61.

[0030] The protrusion 62 protrudes toward the inside of the first insertion hole 61. As shown in Figure 4 and Figure 6 The protrusion 62 has a protruding direction. The front end portion 62a of the protruding direction of the protrusion 62 is in contact with the magnet 22. Hereinafter, when viewed from the axial direction, the inner surface 61a of the first insertion hole 61 that constitutes the inner surface of the protrusion 62 is referred to as the inner surface 61a, and the inner surface 61b that constitutes the portion other than the protrusion 62 is referred to as the inner surface 61b.

[0031] When the magnet 22 is not inserted into the magnet insertion hole 26, the front end portion 62a of the protrusion 62 protrudes into the region in which the magnet 22 is inserted into the magnet insertion hole 26 when viewed from the above-mentioned axial direction. When the magnet 22 is inserted into the magnet insertion hole 26, the front end portion 62a of the protrusion 62 is pushed by the magnet 22 toward the direction opposite to the protruding direction of the protrusion 62.

[0032] Thus, the protrusion 62 pushed by the magnet 22 inserted into the magnet insertion hole 26 is deformed in the above-mentioned opposite direction. Therefore, the restoring force of the deformed protrusion 62 pushes the protrusion 62 in the protruding direction of the protrusion 62. Thus, the magnet 22 is fixed in the magnet insertion hole 26.

[0033] As shown in Figure 4 The second core plate 7 is laminated to the first core plate 6 in the thickness direction. The second core plate 7 has a plurality of second insertion holes 71 and a plurality of recesses 72. The plurality of second insertion holes 71 are located at positions overlapping the plurality of first insertion holes 61 of the first core plate 6 when viewed in the axial direction of the rotor core 21. The second insertion hole 71 penetrates the second core plate 7 in the thickness direction. The second insertion hole 71 constitutes a part of the magnet insertion hole 26.

[0034] Figure 7 is a view of a portion of the second core plate 7 overlapping the first core plate 6 shown in Figure 6 As shown in Figure 7 When the second core plate 7 is viewed from the above-mentioned axial direction, the second insertion hole 71 has an elongated shape in one direction. The magnet 22 is located inside the second insertion hole 71.

[0035] The recess 72 is located radially inward of the second insertion hole 71. More specifically, the recess 72 is located at a position overlapping the protruding portion 62 of the first core plate 6 on the above-described radially inner side. The recess 72 is recessed in a direction opposite to the protruding direction of the protruding portion 62. Hereinafter, from the axial direction, the inner surface of the second insertion hole 71 constituting the recess 72 is referred to as the inner surface 71a, and the inner surface constituting the portion other than the recess 72 is referred to as the inner surface 71b.

[0036] As shown in Figure 7 , of the inner surface of the second insertion hole 71, the connecting portion of the inner surface 71a and the inner surface 71b is sharp. That is, an angle is formed at the connecting portion 71c of the inner surface 71a and the inner surface 71b.

[0037] Although details will be described later, the second insertion hole 71 is formed by blanking processing of a steel sheet using a die. In general, in order to form an angle by blanking processing, different dies must be used to form one face and the other face of the two faces constituting the above-described angle. That is, in the second core plate 7, the recess 72 and the portion other than the recess 72 are formed using different dies.

[0038] In the present embodiment, the second insertion hole 71 is formed by the die that forms the first insertion hole 61 of the first core plate 6. The recess 72 is formed by blanking the region R overlapping the protruding portion 62 of the first core plate 6 when viewed from the above-described axial direction using a die different from the above-described die. The manufacturing method of the first insertion hole 61 and the second insertion hole 71 will be described in detail later.

[0039] Therefore, in the rotor core 21, the inner surface position of the inner surface of the first insertion hole 61 other than the inner surface of the protruding portion 62 and the vicinity thereof coincides with the inner surface position of the inner surface of the second insertion hole 71 other than the inner surface of the recess 72 and the vicinity thereof when the rotor core 21 is viewed from the axial direction. That is, in the rotor core 21, even if a plurality of core plates 25 are laminated, it is possible to suppress the generation of unevenness in the axial direction inside the magnet insertion hole 26. Therefore, in the rotor core 21, it is possible to easily insert the magnet 22 into the magnet insertion hole 26. Therefore, it is possible to realize a structure of the rotor 2 that can be efficiently manufactured. In addition, when the magnet 22 is inserted into the magnet insertion hole 26, it is possible to suppress damage to the magnet 22 due to unevenness inside the magnet insertion hole 26. Therefore, it is possible to obtain a rotor 2 in which deterioration of magnetic characteristics is suppressed.

[0040] (Method of manufacturing rotor) Next, a method of manufacturing the exemplary rotor 2 of the first embodiment will be described with reference to Figure 4 , Figure 8 , and Figure 9A As shown in Figure 8As shown, the manufacturing method of rotor 2 includes core plate forming process S1, protrusion removal process S2, lamination process S3, and magnet insertion process S4.

[0041] The core board forming process S1 is the process of forming multiple core boards W1. In the core board forming process S1, the steel plate 90 is punched to form multiple insertion holes 91 and multiple protrusions 62. The insertion holes 91 are through holes that become the first insertion hole 61 of the first core board 6 or the second insertion hole 71 of the second core board 7. Figure 9A A core plate W1 with an insertion hole 91 and a plurality of protrusions 62 is shown.

[0042] The protrusion removal process S2 is a process for removing the protrusion 62 formed in the core board forming process S1. In this embodiment, in the protrusion removal process S2, a certain area R, including the protrusion 62 formed in the core board forming process S1, is punched away using a punch. Thus, the protrusion 62 is removed from the core board W1. Figure 9B In the diagram, the area R to be punched in steel plate 90 is represented by a dashed line. The area R through which the core plate W1 is punched is shown... Figure 9C As shown, a core plate W2 is formed with the protrusion 62 removed.

[0043] In this embodiment, all protrusions 62 are removed from a portion of the multiple core boards W1 formed in the core board forming process S1. The core board W2 with the protrusions 62 removed becomes a second core board 7 having a second insertion hole 71. On the other hand, the core board W1 with the protrusions 62 not removed becomes a first core board 6 having a first insertion hole 61.

[0044] In addition, in the protrusion removal process S2, a portion of the protrusions 62 can be removed from a portion of the core plates W1 formed in the core plate forming process S1.

[0045] In this embodiment, the protrusion 62 is removed by punching away a certain area R, including the protrusion 62. However, the protrusion 62 can also be removed by other methods. For example, the protrusion 62 can be removed by scraping.

[0046] like Figure 9B As shown, in this embodiment, when viewing the core plate W1 from the aforementioned thickness direction, the protrusion 62 is removed by punching the steel plate 90 at a position further than the base end of the protrusion 62 and in the opposite direction to the protrusion direction of the protrusion 62. The base end of the protrusion 62 refers to the root of the protrusion 62 that protrudes into the insertion hole 91.

[0047] Therefore, as Figure 9CAs shown, the recess 72 is formed on the inner surface of the insertion hole 91. That is, by removing the protrusion 62, the second core plate 7 having the second insertion hole 71 and the recess 72 is formed. Among the plurality of core plates W1 formed in the core plate forming step S1, the core plate W1 remaining with the protrusion 62 not removed becomes the first core plate 6 having the first insertion hole 61 and the protrusion 62.

[0048] In this way, the recess 72 of the second core plate 7 is formed by a different step from the step of forming the insertion hole 91. Therefore, in the inner surface of the insertion hole 91 of the second core plate 7, an angle is formed at a connection portion 71c between an inner surface 71a constituting the recess 72 and an inner surface 71b constituting a portion other than the recess 72.

[0049] In the manufacturing method described above, the inner surface 71b constituting a portion other than the recess 72 in the inner surface of the second insertion hole 71 and the inner surface 61b constituting a portion other than the protrusion 62 in the inner surface of the first insertion hole 61 are formed using the same die. Thereby, in a state in which a plurality of core plates 25 are stacked, it is possible to align the inner surface positions of the first insertion hole 61 and the second insertion hole 71 constituting each magnet insertion hole 26 with high precision.

[0050] In addition, in the protrusion removing step S2, by forming the recess 72, it is possible to prevent a portion of the inner surface of the second insertion hole 71 from protruding into the magnet insertion hole 26 of the rotor core 21. In addition, it is possible to prevent burrs and the like formed when the protrusion 62 is punched out from protruding into the magnet insertion hole 26. Therefore, it is possible to prevent the recess 72 formed on the inner surface of the second insertion hole 71 as a trace left by removing the protrusion 62 from interfering with the insertion of the magnet 22 into the magnet insertion hole 26.

[0051] The stacking step S3 is a step of stacking a plurality of core plates 25. Specifically, in the stacking step S3, a plurality of first core plates 6 having the protrusion 62 and a plurality of second core plates 7 having the recess 72 are stacked. Thereby, the cylindrical rotor core 21 having a plurality of core plates 25 stacked in the thickness direction and a plurality of magnet insertion holes 26 extending in the axial direction is formed.

[0052] The magnet insertion step S4 is a step of inserting the magnet 22 into each of the plurality of magnet insertion holes 26 and holding the magnet 22 in contact with the protrusion 62.

[0053] As described above, when the magnet 22 is not inserted into the magnet insertion hole 26, the leading end portion 62a of the protrusion 62 protrudes into a region in which the magnet 22 is inserted into the first insertion hole 61 as viewed from the above-described axial direction. When the magnet 22 is inserted into the magnet insertion hole 26, the leading end portion 62a of the protrusion 62 is pushed by the magnet 22 in a direction opposite to the protruding direction of the protrusion 62.

[0054] Thus, the protrusion 62 pushed by the magnet 22 inserted into the magnet insertion hole 26 is deformed in the opposite direction described above. Therefore, the restoring force of the deformed protrusion 62 of the magnet 22 pushes in the protruding direction of the protrusion 62. Thus, the magnet 22 is fixed in the magnet insertion hole 26.

[0055] As described above, the manufacturing method of the exemplary rotor 2 of the present embodiment is a manufacturing method of a rotor 2 provided with a cylindrical rotor core 21 and a plurality of magnets 22, the rotor core 21 having a plurality of core plates 25 stacked in a thickness direction and a plurality of magnet insertion holes 26 extending in an axial direction, and the plurality of magnets 22 being respectively inserted into the plurality of magnet insertion holes 26. The manufacturing method of the rotor 2 includes a core plate forming process S1, a protrusion removing process S2, a stacking process S3, and a magnet inserting process S4.

[0056] The core plate forming process S1 includes blanking a steel plate 90 to form a plurality of core plates having a plurality of insertion holes 91 and a plurality of protrusions 62, the plurality of insertion holes 91 respectively constituting a part of the plurality of magnet insertion holes 26 by penetrating the steel plate 90 in the thickness direction, and the plurality of protrusions 62 protruding toward the inside of the plurality of insertion holes 91. In the protrusion removing process S2, at least one of the plurality of protrusions 62 is removed from at least some of the plurality of core plates formed in the core plate forming process S1. In the stacking process S3, the magnet insertion hole 26 is constituted by the first insertion hole 61 having the protrusion 62 protruding toward the inside and the second insertion hole 71 from which the protrusion 62 is removed by stacking the plurality of core plates. In the magnet inserting process S4, the magnet 22 is inserted into the plurality of magnet insertion holes 26 and held in contact with the protrusion 62.

[0057] In the manufacturing method described above, first, a plurality of core plates having a plurality of insertion holes 91 and protrusions 62 respectively protruding toward the inside of the plurality of insertion holes 91 are formed. Next, some of the plurality of protrusions 62 are removed. Thus, the first insertion hole 61 in which the protrusion 62 protrudes toward the inside and the second insertion hole 71 in which the protrusion does not protrude toward the inside are formed. In this way, in the method described above, the first insertion hole 61 in which the protrusion 62 protrudes and the second insertion hole 71 in which the protrusion does not protrude are formed using the same die. Thus, in the state in which the plurality of core plates are stacked, the position of the inner surface of the first insertion hole 61 constituting each magnet insertion hole 26 and the position of the inner surface of the second insertion hole 71 can be accurately aligned. This makes it possible to easily insert the magnet 22 into the magnet insertion hole 26. Therefore, it is possible to improve the manufacturing efficiency of the rotor 2. In addition, it is possible to suppress damage to the magnet 22 when the magnet 22 is inserted into the magnet insertion hole 26. Thus, it is possible to prevent deterioration of the magnetic characteristics of the rotor 2.

[0058] In the present embodiment, the protrusion removing step S2 removes all the protrusions 62 from at least some of the plurality of core plates W1 formed in the core plate forming step S1. In the stacking step S3, the first core plate 6 having the plurality of protrusions 62 and the second core plate 7 from which the plurality of protrusions are removed are stacked together.

[0059] In the present embodiment, the first core plate 6 having the plurality of protrusions 62 and the second core plate 7 from which the plurality of protrusions 62 are removed are formed by the core plate forming step S1 and the protrusion removing step S2. Thereby, in the rotor core 21, in a state where the first core plate 6 and the second core plate 7 are stacked, it is possible to make the protrusions 62 protruding toward the inside of the plurality of magnet insertion holes 26 to be located at the same axial direction position in the plurality of magnet insertion holes 26. Thereby, when the magnets 22 are respectively inserted into the plurality of magnet insertion holes 26, it is possible to make each of the magnets 22 contact the protrusions 62 at the same time. Therefore, in the present embodiment, in the magnet inserting step S4, it is not necessary to change the way of applying a force to the magnets 22 for each of the magnet insertion holes 26. Therefore, it is possible to improve the workability of the work of inserting the magnets 22 into the magnet insertion holes 26. Therefore, it is possible to improve the manufacturing efficiency of the rotor 2.

[0060] In addition, the exemplary rotor 2 of the present embodiment manufactured by the above-described method has the columnar rotor core 21 having the plurality of core plates 25 stacked in the thickness direction and the magnet insertion holes 26 extending in the axial direction, and the magnets 22 inserted into the magnet insertion holes 26, and the plurality of core plates 25 have the first core plate 6 and the second core plate 7 stacked in the thickness direction with respect to the first core plate 6. The first core plate 6 has the first insertion hole 61 passing through the first core plate 6 in the thickness direction and constituting a part of the magnet insertion hole 26, and the protrusion 62 protruding toward the inside of the first insertion hole 61 and contacting the magnet 22. The second core plate 7 has the second insertion hole 71 passing through the second core plate 7 in the thickness direction and constituting a part of the magnet insertion hole 26, and the recess 72 located on the inner surface constituting the second insertion hole 71 and recessed toward a direction opposite to the protruding direction of the protrusion 62 in the first core plate 6 when the rotor core 21 is viewed from the above-described axial direction. On the above-described inner surface of the second insertion hole 71, a connection portion 71c between the inner surface 71a constituting the recess 72 and the inner surface 71b constituting a portion other than the recess 72 is angular.

[0061] In the second core board 7 manufactured by the above method, an angle is formed on the inner surface of the second insertion hole 71. One side and the other side of the angle are punched out using different dies. That is, the second insertion hole 71 of the second core board 7 is formed by a die forming the recess 72 and a die forming the portion other than the recess 72. Specifically, the second insertion hole 71 is formed by a die forming the first insertion hole 61. The recess 72 of the second insertion hole 71 is formed by a die punching out a defined area including the protrusion.

[0062] Therefore, when viewing the rotor core 21 from the axial direction, the position of the inner surface 71b of the second insertion hole 71 (excluding the portion constituting the recess 72) can be precisely aligned with the position of the inner surface 61b of the first insertion hole 61 (excluding the portion constituting the protrusion 62). This makes it easy to insert the magnet 22 into the magnet insertion hole 26. Therefore, a rotor 2 with improved workability in inserting the magnet 22 into the magnet insertion hole 26 can be obtained. Thus, a rotor 2 structure that can be manufactured efficiently can be achieved. Furthermore, when the magnet 22 is inserted into the magnet insertion hole 26, damage to the magnet 22 due to unevenness within the magnet insertion hole 26 can be suppressed. Therefore, a rotor 2 with suppressed magnetic property degradation can be obtained.

[0063] (Second Implementation) Next, we will refer to Figures 10 to 12 An exemplary rotor 102 of the second embodiment will be described. In the rotor 102 of this embodiment, the first core plate 106 has a deformation-allowing portion 163 that allows the protrusion 62 to deform, which is different from the structure of the first core plate 6 of the first embodiment. Hereinafter, structures that are the same as those in the first embodiment will be labeled with the same reference numerals and their descriptions will be omitted, while structures that are different from those in the first embodiment will be described.

[0064] (Structure of the rotor) like Figure 10 As shown, the rotor 102 has a rotor core 121 and a magnet 22. The rotor core 121 has a rear end face 121a in the magnet insertion direction and a front end face in the magnet insertion direction (not shown). The rotor core 121 has a plurality of core plates 125 and magnet insertion holes 126. The structure of the magnet insertion holes 126 is the same as that of the magnet insertion holes 26 in the first embodiment, so its description is omitted.

[0065] In this embodiment, the plurality of core plates 125 include a first core plate 106 and a second core plate 7. The first core plate 106 and the second core plate 7 are stacked along the axial direction of the rotor core 121.

[0066] like Figure 11 and Figure 12As shown, the first core board 106 has a plurality of first insertion holes 61, a plurality of protrusions 62, and a plurality of deformation-allowing portions 163. Figure 12 As shown, in this embodiment, the first core plate 106 has two protrusions 62 and two deformation-allowing portions 163 on the radially inner side of a first insertion hole 61.

[0067] The deformation-allowing portion 163 is located in a direction opposite to the direction in which the first insertion hole 61 is positioned relative to the protrusion 62 in the arrangement direction of the first insertion hole 61 and the protrusion 62. That is, the first core plate 106 has a deformation-allowing portion 163, which is located in a direction opposite to the direction in which the first insertion hole 61 is positioned relative to the protrusion 62 in the arrangement direction of the first insertion hole 61 and the protrusion 62, and allows the protrusion 62 to deform in the aforementioned opposite direction.

[0068] In this embodiment, the deformation-allowing portion 163 is a through hole penetrating the first core plate 106 along the thickness direction. Figure 11 In the example shown, the deformation allowance 163 is located radially inside the first insertion hole 61. The deformation allowance 163 is rectangular when viewed from the axial direction. The deformation allowance 163 has a shape that is longer in a direction orthogonal to the protrusion direction of the protrusion 62.

[0069] The deformation-allowing part 163 allows the protrusion 62 to deform in the opposite direction described above. More specifically, as... Figure 12 As shown, when the protrusion 62 is pressed in the opposite direction, the deformation-allowing portion 163, which serves as a through hole, allows the protrusion 62 to move in the opposite direction. Furthermore, the deformation-allowing portion can have a structure that allows the protrusion to deform in the opposite direction. For example, the deformation-allowing portion can be thin-walled. The deformation-allowing portion can have any shape, as long as it allows the protrusion to deform in the opposite direction.

[0070] Figure 12 The dashed lines indicate the positions of the protrusion 62 and the deformation-allowing part 163 when the magnet 22 is not inserted into the magnet insertion hole 26. Figure 12 As shown by the dashed line, when viewed from the axial direction, if the magnet 22 is not inserted into the magnet insertion hole 126, the front end 62a of the protrusion 62 protrudes into the area of ​​the magnet insertion hole 126 where the magnet 22 is inserted.

[0071] When magnet 22 is inserted into magnet insertion hole 126, protrusion 62 is pushed by magnet 22 in the opposite direction. Deformation-allowing part 163 is located in the opposite direction. When protrusion 62 is pushed in the opposite direction, protrusion 62 moves in the opposite direction as shown by the solid line in Figure 12.

[0072] That is, when the magnet 22 is inserted into the magnet insertion hole 126, the deformation permitting portion 163 allows the protruding portion 62 to move toward the deformation permitting portion 163. Thus, the force applied to the magnet 22 from the protruding portion 62 can be reduced when the magnet 22 is inserted into the magnet insertion hole 126. Thus, the workability of the work of inserting the magnet 22 into the magnet insertion hole 126 in the manufacturing process of the rotor 102 can be improved.

[0073] The first core plate 106 is made of metal. Therefore, the region R extending along the first insertion hole 61 between the base end portion of the protruding portion 62 and the deformation permitting portion 163 functions as a leaf spring. That is, when the protruding portion 62 moves in the above-mentioned opposite direction, the region R deforms in the above-mentioned opposite direction. Thus, a restoring force is generated in the region R. Hereinafter, the deformation of the region R is also referred to as the deformation of the protruding portion 62.

[0074] In the present embodiment, the deformation permitting portion 163 is a through-hole that penetrates the first core plate 106 in the thickness direction. Therefore, when the magnet 22 is inserted into the magnet insertion hole 126, the protruding portion 62 can easily move toward the deformation permitting portion 163. This makes it easier for the magnet 22 to be inserted into the magnet insertion hole 126. Therefore, the workability of the work of inserting the magnet 22 into the magnet insertion hole 126 can be further improved. Thus, the manufacturing efficiency of the rotor 102 can be improved.

[0075] The magnet 22 inserted into the magnet insertion hole 126 is pushed toward the protruding direction of the protruding portion 62 by the restoring force of the protruding portion 62 deformed in the above-mentioned opposite direction. Thus, the magnet 22 is fixed in the magnet insertion hole 126.

[0076] (Method of manufacturing rotor) Next, a method of manufacturing an exemplary rotor 102 according to a second embodiment will be described with reference to Figure 13 and Figure 14 Figure 13 is a flowchart showing a method of manufacturing the rotor 102. As shown in Figure 13 , the method of manufacturing the rotor 102 includes a through-hole forming process S11, a core plate forming process S12, a protruding portion removing process S13, a laminating process S14, and a magnet inserting process S15.

[0077] The through-hole forming process S11 is a process of forming a through-hole 93 in the steel plate 90, the through-hole 93 penetrating the steel plate 90 in the thickness direction. The through-hole 93 becomes the deformation permitting portion 163 of the first core plate 106. That is, in the through-hole forming process S11, the through-hole 93 is formed in the portion of the steel plate 90 that will become the deformation permitting portion 163 in the region of the steel plate 90 that will become the first core plate 106. On the other hand, in the through-hole forming process S11, no through-hole that will become a deformation permitting portion is formed in the region of the steel plate 90 that will become the second core plate 7. ​

[0078] The core plate forming step S12 is a step of blanking the steel plate 90 to form the core plate 25 having the plurality of insertion holes 91 and the plurality of protrusions 62. The core plate forming step S12 is the same as the core plate forming step S1 in the first embodiment. In the present embodiment, in the core plate forming step S12, both the steel plate 90 in which the through hole 93 is formed in the through hole forming step S11 and the steel plate 90 in which the through hole 93 is not formed are blanked.

[0079] The protrusion removing step S13 is a step of removing the protrusions 62 formed in the core plate forming step S12. The protrusion removing step S13 is the same as the protrusion removing step S2 in the first embodiment. In the protrusion removing step S13 of the present embodiment, among the plurality of protrusions 62, the protrusions 62 in which the through hole 93 is not formed at a position opposite to the direction in which the insertion hole 91 is located in the arrangement direction of the insertion hole 91 and the protrusion 62 are removed. In the present embodiment, among the plurality of protrusions 62, the protrusions 62 in which the through hole 93 is not formed at a position opposite to the direction in which the insertion hole 91 is located in the arrangement direction of the insertion hole 91 and the protrusion 62 are all removed.

[0080] Thus, for the insertion hole 91 in which the protrusion 62 protrudes inward, the through hole 93 is formed at a position opposite to the direction in which the insertion hole 91 is located in the arrangement direction of the insertion hole 91 and the protrusion 62. By forming the through hole 93 in the core plate having the protrusion 62, the magnet 22 can be easily inserted into the magnet insertion hole 126. Therefore, the workability of the work of inserting the magnet 22 into the magnet insertion hole 126 can be further improved. Thus, the manufacturing efficiency of the rotor 102 can be improved.

[0081] Figure 14 Examples of the dies M1, M2, and M3 that blank the steel plate 90 and examples of the respective core plates formed by the dies M1, M2, and M3 are shown.

[0082] The through hole forming step S11 is performed using the die M1. As shown in FIG. 6, the die M1 has a punch B1. The die M1 blanks the steel plate 90 using the punch B1 by moving the punch B1 toward the steel plate 90. Thus, the core plate W61 in which the through hole 93 that penetrates the steel plate 90 in the thickness direction is formed is obtained. Figure 14

[0083] In the present embodiment, the die M1 has an adjustment portion that shortens the movement distance of the punch B1. The adjustment portion is not shown in the drawings. When the movement distance of the punch B1 is adjusted to be short by the above adjustment portion, the punch B1 does not reach the steel plate 90. In other words, when the movement distance of the punch B1 is adjusted to be short, the punch B1 does not punch through the steel plate 90. Thus, the through hole 93 can not be formed in the die M1. Therefore, in the through hole forming step S11, the core plate W71 in which the through hole 93 is not formed can also be obtained.​

[0084] Thus, in the through-hole forming step S11, the core plate W61 in which the through-hole 93 is formed and the core plate W71 in which the through-hole 93 is not formed are obtained.

[0085] The core plate forming step S12 is performed on the core plate W61 in which the through-hole 93 is formed and the core plate W71 in which the through-hole 93 is not formed using the die M2. As shown in FIG. 6, the die M2 has a punch B2. The die M2 punches the steel plate 90 using the punch B2 by moving the punch B2 toward the steel plate 90. Thus, the core plate W62 in which the through-hole 93, the insertion hole 91, and the protrusion 62 are formed and the core plate W72 in which the insertion hole 91 and the protrusion 62 are formed are obtained. The core plate W62 becomes the first core plate 106 of the rotor core 121. The core plate W72 becomes the second core plate 7 of the rotor core 121. Figure 14

[0086] In the present embodiment, the insertion hole 91 is formed in the steel plate 90 near the through-hole 93. Generally, when through-holes are sequentially formed at positions close to each other, there is a possibility that the through-hole formed later deforms the through-hole formed earlier.

[0087] Since the magnet is inserted into the insertion hole 91, high-precision processing is required. On the other hand, the through-hole 93 only needs to function as a deformation permitting portion 163 that permits the protrusion 62 to deform. Therefore, the through-hole 93 does not need high-precision processing compared to the insertion hole 91.

[0088] In the above-described method, the insertion hole 91 is formed after the through-hole 93. Therefore, deformation of the insertion hole 91 is suppressed. Thus, the processing precision of the insertion hole 91 can be improved. Therefore, in the lamination step S14, the positions of the inner surfaces of the first insertion hole 61 of the first core plate 106 in which the through-hole 93 is formed and the second insertion hole 71 of the second core plate 7 in which the through-hole is not formed can be accurately aligned. That is, even if the rotor core 121 is laminated with a plurality of core plates 125, the axis direction unevenness in the magnet insertion hole 126 can be suppressed. Therefore, the workability of the work of inserting the magnet 22 into the magnet insertion hole 126 can be improved. In addition, damage to the magnet 22 when the magnet 22 is inserted into the magnet insertion hole 126 can be suppressed. Thus, deterioration of the magnetic characteristics of the rotor 102 can be prevented.

[0089] The protrusion removing step S13 is performed on the core plate W62 in which the through-hole 93, the insertion hole 91, and the protrusion 62 are formed and the core plate W72 in which the insertion hole 91 and the protrusion 62 are formed using the die M3. As shown in FIG. 7, the die M3 has a punch B3. The die M3 punches the steel plate 90 using the punch B3 by moving the punch B3 toward the steel plate 90. Thus, the core plate W73 in which the protrusion 62 formed in the steel plate 90 is removed is obtained. Figure 14 ​​

[0090] In the present embodiment, the die M3 has an adjustment portion that shortens the moving distance of the punch B3. The adjustment portion is not shown in the drawings. When the moving distance of the punch B3 is adjusted to be shorter by the above adjustment portion, the punch B3 does not reach the steel sheet 90. That is, when the moving distance of the punch B3 is adjusted to be shorter, the punch B3 does not punch through the steel sheet 90. Therefore, the die M3 can not remove the protruding portion 62. Therefore, in the protruding portion removal process S13, the core plate W63 in which the protruding portion 62 is not removed can also be obtained.

[0091] In the present embodiment, the die M3 adjusts the moving distance of the punch B3 with respect to the core plate W72 to be longer. Therefore, the punch B3 punches off the protruding portion 62 formed in the core plate W72. On the other hand, the die M3 adjusts the moving distance of the punch B3 with respect to the core plate W62 to be shorter. Therefore, the punch B3 does not punch off the protruding portion 62 formed on the core plate W62.

[0092] Thus, in the protruding portion removal process S13, the core plate W63 in which the through hole 93, the insertion hole 91, and the protruding portion 62 are formed and the core plate W73 in which the insertion hole 91 and the recessed portion 72 are formed are obtained. The core plate W63 becomes the first core plate 106 of the rotor core 121. The core plate W73 becomes the second core plate 7 of the rotor core 121.

[0093] The lamination process S14 is a process of laminating a plurality of core plates 125. The lamination process S14 is the same as the lamination process S3 of the first embodiment. Specifically, in the lamination process S14, a plurality of first core plates 106 having the protruding portion 62 and a plurality of second core plates 7 having the recessed portion 72 are laminated. Thus, the columnar rotor core 121 having a plurality of core plates 125 laminated in the thickness direction and a plurality of magnet insertion holes 126 extending in the axial direction is formed.

[0094] The magnet insertion process S15 is a process of inserting the magnet 22 into each of the plurality of magnet insertion holes 126 and holding the magnet 22 in contact with the protruding portion 62. The magnet insertion process S15 is the same as the magnet insertion process S4 of the first embodiment, and thus the description is omitted.

[0095] As described above, the manufacturing method of the rotor 102 of the present embodiment further includes a through hole forming process S11 of forming a through hole 93 in a steel sheet 90, the through hole 93 penetrating the steel sheet 90 in the thickness direction to allow a portion of the steel sheet 90 to be deformed. In the core plate forming process S12, the steel sheet 90 in which the through hole 93 is formed in the through hole forming process S11 is punched to form a plurality of core plates 125 each having a plurality of insertion holes 91 and a plurality of protruding portions 62.

[0096] When multiple through holes are formed in close proximity to each other on a steel plate, there is a possibility that the previously formed through holes may deform when subsequent through holes are formed.

[0097] In contrast, in the method described above, the insertion hole 91 is formed after the through hole 93 is formed. Therefore, deformation of the insertion hole 91 is suppressed. As a result, in the state of stacked core plates 125, the position of the inner surface of the first insertion hole 61 of the first core plate 106 with the deformation allowance portion 163 formed can be precisely aligned with the position of the inner surface of the second insertion hole 71 of the second core plate 7 without the deformation allowance portion formed. This allows the magnet 22 to be easily inserted into the magnet insertion hole 126. Therefore, the workability of inserting the magnet 22 into the magnet insertion hole 126 can be improved. Therefore, the manufacturing efficiency of the rotor 102 can be improved. Furthermore, damage to the magnet 22 when it is inserted into the magnet insertion hole 126 can be suppressed. Therefore, the deterioration of the magnetic properties of the rotor 102 can be prevented.

[0098] (Third Implementation) Next, we will refer to Figures 15 to 17 An exemplary rotor 202 according to the third embodiment will be described. In the rotor 202 of this embodiment, in addition to the first core plate 206 and the second core plate 207, the plurality of core plates 225 also include a third core plate 208. Hereinafter, structures that are the same as those in the first and second embodiments will be labeled with the same symbols and their descriptions will be omitted, while structures that are different from those in the first and second embodiments will be described.

[0099] (Structure of the rotor) like Figure 15 As shown, the rotor 202 has a rotor core 221 and a magnet 22. The rotor core 221 has a rear end face 221a in the magnet insertion direction and a front end face in the magnet insertion direction (not shown). The rotor core 221 has a plurality of core plates 225 and magnet insertion holes 226. The structure of the magnet insertion holes 226 is the same as that of the magnet insertion holes 26 in the first embodiment, so its description is omitted.

[0100] Multiple core boards 225 are stacked along the thickness direction. In this embodiment, the multiple core boards 225 include a first core board 206, a second core board 207, and a third core board 208.

[0101] The first core plate 206 has a plurality of first insertion holes 61, a plurality of protrusions 62, and a plurality of first deformation-allowing portions 263. In the arrangement direction of the first insertion holes 61 and the protrusions 62, the first deformation-allowing portions 263 are located in a direction opposite to the direction in which the first insertion holes 61 are positioned relative to the protrusions 62. The structure of the first deformation-allowing portion 263 is the same as that of the deformation-allowing portion 163 in the second embodiment, therefore its description is omitted. The first deformation-allowing portion 263 is the deformation-allowing portion of the present invention.

[0102] In the present embodiment, as in the second embodiment, a region R extending along the first insertion hole 61 between the base end portion of the protruding portion 62 and the first deformation permitting portion 263 functions as a leaf spring. That is, when the protruding portion 62 moves in the opposite direction described above, the region R deforms in the opposite direction described above. Thereby, a restoring force is generated in the region R. Therefore, the protruding portion 62 moving in the opposite direction described above pushes the magnet 22 inserted into the magnet insertion hole 226 in the protruding direction by the restoring force of the region R. Thereby, the magnet 22 is fixed in the magnet insertion hole 226.

[0103] The second core plate 207 has a plurality of second insertion holes 71 and a plurality of second recessed portions 272. The structure of the second recessed portion 272 is the same as that of the recessed portion 72 in the first embodiment, and thus the description thereof is omitted. The second recessed portion 272 is the recessed portion of the present application.

[0104] The third core plate 208 has a plurality of third insertion holes 281, a plurality of third recessed portions 282, and a plurality of third deformation permitting portions 283.

[0105] When viewed in the axial direction of the rotor core 221, the plurality of third insertion holes 281 are located at positions overlapping the plurality of first insertion holes 61 of the first core plate 206 and the plurality of second insertion holes 71 of the second core plate 207. The third insertion hole 281 penetrates the third core plate 208 in the thickness direction. The third insertion hole 281 constitutes a portion of the magnet insertion hole 226.

[0106] The plurality of third recessed portions 282 are located radially inward of the third insertion hole 281. When viewed in the axial direction described above, the plurality of third recessed portions 282 are located at positions overlapping the plurality of second recessed portions 272 of the second core plate 207. That is, the third recessed portion 282 is recessed in the direction opposite to the protruding direction of the protruding portion 62 of the first core plate 206. Hereinafter, from the axial direction, the inner surface of the third insertion hole 281 constituting the third recessed portion 282 is referred to as an inner surface 281a, and the inner surface constituting a portion other than the third recessed portion 282 is referred to as an inner surface 281b.

[0107] The plurality of third deformation permitting portions 283 are located at positions overlapping the plurality of first deformation permitting portions 263 of the first core plate 106 when viewed in the axial direction described above. The third deformation permitting portion 283 is rectangular when viewed in the axial direction.

[0108] In the present embodiment, the third deformation permitting portion 283 is a through-hole that penetrates the third core plate 208 in the thickness direction. The third deformation permitting portion 283 permits deformation of the region R extending along the third insertion hole 281 between the third recessed portion 282 and the third deformation permitting portion 283 to the third deformation permitting portion 283 side. The third deformation permitting portion 283 can have a structure that permits deformation of the region R. For example, the third deformation permitting portion can be thin-walled. The third deformation permitting portion can be any shape as long as it can deform the region R to the third deformation permitting portion 283 side.

[0109] The third insertion hole 281 and the third recessed portion 282 of the third core plate 208 are formed by the same method as the second insertion hole 71 and the second recessed portion 272 of the second core plate 207.

[0110] That is, in the present embodiment, the third insertion hole 281 is formed by a mold that forms the first insertion hole 61 and the second insertion hole 71 of the first core plate 206. The third recessed portion 282 is formed by using a different mold from the above-described mold to punch the region that becomes the protruding portion 62 on the steel sheet 90 on which the insertion hole 91 is formed.

[0111] Therefore, in the rotor core 221, the position of the inner surface 61b of the first insertion hole 61, the position of the inner surface 71b of the second insertion hole 71, and the position of the inner surface 281b of the third insertion hole 281 align when the rotor core 221 is viewed from the axis direction. That is, even if the rotor core 221 is laminated with a plurality of core plates 225, it is possible to suppress generation of unevenness in the magnet insertion hole 226 in the axis direction. Therefore, in the rotor core 221, it is possible to easily insert the magnet 22 into the magnet insertion hole 226. Therefore, it is possible to realize a structure of the rotor 202 that can be efficiently manufactured. In addition, it is possible to suppress damage to the magnet 22 when the magnet 22 is inserted into the magnet insertion hole 226. Therefore, it is possible to prevent deterioration of the magnetic characteristics of the rotor 202.

[0112] The third deformation permitting portion 283 of the third core plate 208 is formed by the same method as the first deformation permitting portion 263 of the first core plate 206.

[0113] That is, the third deformation permitting portion 283 is formed before the third insertion hole 281 is formed. Therefore, deformation of the third insertion hole 281 is suppressed. This makes it possible to align the inner surface positions of the first insertion hole 61 of the first core plate 206, the second insertion hole 71 of the second core plate 207, and the third insertion hole 281 of the third core plate 208 with high precision.

[0114] As Figure 17In the present embodiment, the third core plate 208 is laminated on the front side in the magnet insertion direction with respect to the first core plate 206, as shown. The second core plate 207 is laminated on the rear side of the first core plate 206 in the magnet insertion direction and on the front side of the third core plate 208 in the magnet insertion direction. That is, in the present embodiment, a plurality of second core plates 207 are laminated on the front side and the rear side in the magnet insertion direction of one first core plate 206 and one third core plate 208 adjacent to each other in the lamination direction.

[0115] In the rotor core in which the protrusions hold the magnets, when the magnets are inserted into the magnet insertion holes, the protrusions can be bent in the magnet insertion direction. As a result, there is a possibility that the protrusions will be sandwiched between the other core plate laminated on the front side in the magnet insertion direction with respect to the core plate having the protrusions and the magnets. This can cause a large force to be applied to the magnets.

[0116] In the above structure, the third core plate 208 having the third deformation permitting portion 283 is laminated on the first core plate 206 in the magnet insertion direction. The inner surface of the third insertion hole 281 is movable toward the third deformation permitting portion 283. Therefore, when the protrusion 62 of the first core plate 206 is bent in the magnet insertion direction, the inner surface of the third insertion hole 281 moves toward the third deformation permitting portion 283 side. This can prevent the magnets 22 from being subjected to a large force. Therefore, in the rotor core 221, it is possible to easily insert the magnets 22 into the magnet insertion holes 226. Therefore, it is possible to realize a structure of the rotor 202 capable of improving the workability of the work of inserting the magnets 22 into the magnet insertion holes 226.

[0117] (Method of manufacturing rotor) Next, a method of manufacturing an exemplary rotor 202 of the third embodiment will be described with reference to Figure 18 The method of manufacturing the rotor 202 includes a through-hole forming process S11, a core plate forming process S12, a protrusion removing process S23, a lamination process S24, and a magnet insertion process S15. Figure 18 Examples of each core plate formed by the through-hole forming process S11, the core plate forming process S12, and the protrusion removing process S23 are shown.

[0118] The core plates 225 of the rotor 202 are manufactured using the molds M1, M2, and M3 used in the through-hole forming process S11, the core plate forming process S12, and the protrusion removing process S13 of the second embodiment. Further, in the Figure 18 In the present embodiment, the illustrations of the molds M1, M2, M3 are omitted.

[0119] As described above, in the present embodiment, the protrusions 62 of the first core plate 206 are removed by the protrusion removing process S23. Therefore, the first core plate 206 is not bent in the magnet insertion direction when the magnets 22 are inserted into the magnet insertion holes 226. As a result, the magnets 22 are not subjected to a large force. Therefore, it is possible to easily insert the magnets 22 into the magnet insertion holes 226. Therefore, it is possible to realize a structure of the rotor 202 capable of improving the workability of the work of inserting the magnets 22 into the magnet insertion holes 226. Figure 18As shown, in the protrusion removal process S23 of the present embodiment, the protrusions 62 that do not have the through-hole 93 formed at the position opposite to the direction in which the insertion hole 91 is present in the arrangement direction of the insertion hole 91 and the protrusions 62 are removed. In addition, the protrusion removal process S23 also removes a portion of the protrusions 62 that have the through-hole 93 formed at the position opposite to the direction in which the insertion hole 91 is present in the arrangement direction of the insertion hole 91 and the protrusions 62.

[0120] Specifically, in the protrusion removal process S23, the protrusions 62 formed in the core plate W72 are removed. Thus, the core plate W73 in which the insertion hole 91 and the second recess 272 are formed is obtained. The core plate W73 becomes the second core plate 207 of the rotor core 221.

[0121] In the protrusion removal process S23, a portion of the protrusions 62 formed in the core plate W62 are removed. Thus, the core plate W63 in which the through-hole 93, the insertion hole 91, and the protrusions 62 are formed and the core plate W83 in which the through-hole 93, the insertion hole 91, and the third recess 282 are formed are obtained. The core plate W63 becomes the first core plate 206 of the rotor core 221. The core plate W83 becomes the third core plate 208 of the rotor core 221.

[0122] The lamination process S24 is a process of laminating a plurality of core plates 225. In the lamination process S24, the third core plate 208 is laminated on the front side in the magnet insertion direction of the first core plate 206. In addition, the second core plate 207 is laminated on the rear side in the magnet insertion direction of the first core plate 206 and on the front side in the magnet insertion direction of the third core plate 208. Thus, the cylindrical rotor core 221 having a plurality of core plates 225 laminated in the thickness direction and a plurality of magnet insertion holes 226 extending in the axial direction is formed.

[0123] Thus, in the manufacturing method of the exemplary rotor 202 of the present embodiment, in the protrusion removal process S23, of the plurality of protrusions 62, at least one protrusion 62 having the through-hole 93 formed at the position opposite to the direction in which the insertion hole 91 is present in the arrangement direction of the insertion hole 91 and the insertion hole 91 and at least one protrusion 62 not having the through-hole 93 formed at the position in the opposite direction are removed.

[0124] Thus, for a portion of the core plates having the insertion hole 91 from which the protrusion protruding inward has been removed, the third core plate 208 having the third deformation allowance portion 283 at the position in the above-mentioned opposite direction is formed. Therefore, for example, the third core plate 208 from which the protrusion 62 is removed and which has the third deformation allowance portion 283 can be laminated on one side or the other side in the axial direction of the first core plate 206 having the protrusion 62.

[0125] In the rotor core 221, where the third core plate 208 is stacked relative to the first core plate 206 along the thickness direction, for example, when the magnet 22 is inserted into the magnet insertion hole 226, even if the protrusion 62 bends along the magnet insertion direction, a portion of the third core plate 208 can move toward the third deformation-allowing portion 283. This allows the magnet 22 to be easily inserted into the magnet insertion hole 226. Therefore, the workability of inserting the magnet 22 into the magnet insertion hole 226 can be improved. Thus, the manufacturing efficiency of the rotor 202 can be improved.

[0126] (Fourth Implementation) Next, we will refer to Figures 19 to 20 An exemplary rotor 302 according to the fourth embodiment will be described. In the rotor 302 of this embodiment, the plurality of core plates 325 have riveting portions 327, which is different from the structure of the plurality of core plates 125 in the second embodiment. Hereinafter, the same reference numerals will be used to refer to the same structures as in the second embodiment and their descriptions will be omitted, while the structures different from those in the second embodiment will be described.

[0127] like Figure 19 As shown, the rotor 302 has a rotor core 321 and a magnet 22. The rotor core 321 has a rear end face 321a in the magnet insertion direction and a front end face 321b in the magnet insertion direction. The rotor core 321 has a plurality of core plates 325 and a plurality of magnet insertion holes 326. The structure of the magnet insertion holes 326 is the same as that of the magnet insertion hole 126 in the second embodiment, so its description is omitted.

[0128] Multiple core plates 325 are stacked along the thickness direction. In this embodiment, the multiple core plates 325 include, for example, the first core plate 106 and the second core plate 7 of the second embodiment. Alternatively, the multiple core plates may include the first core plate and the second core plate of the first embodiment. The multiple core plates may include the first core plate, the second core plate, and the third core plate of the third embodiment. The core plates 325a and 325b constituting the end faces 321a and 321b on both sides of the rotor core 321 in the axial direction are preferably core plates other than the first core plate.

[0129] like Figure 20 As shown, multiple core plates 325 have riveting portions 327. The riveting portions 327 are formed by pushing the position C of the core plate 325 toward the magnet insertion direction. Specifically, the riveting portion 327 is a recess 327a on the rear side of the core plate 325 in the magnet insertion direction and a protrusion 327b on the front side in the magnet insertion direction.

[0130] The core plate 325b constituting the end face 321b of the rotor core 321 has a protruding through hole 327c for fixing at position C, which extends through the core plate 325b in the thickness direction.

[0131] The plurality of core plates 325 are connected in the thickness direction by the rivet portions 327. That is, in the plurality of core plates 325, the projection 327b of one of the pair of core plates 325 adjacent in the stacking direction is fitted in the recess 327a of the other core plate 325, thereby connecting the core plates 325 adjacent in the stacking direction.

[0132] The core plate 325b constituting the end face 321b and the core plate 325c stacked on the rear side in the magnet insertion direction of the core plate 325b are connected by fitting the projection 327b of the core plate 325c in the projection fixing through-hole 327c of the core plate 325b. This structure can prevent the projection 327b formed on the core plate 325c from protruding from the end face 321b.

[0133] That is, the manufacturing method of the rotor 302 in the present embodiment further includes a rivet portion forming process in which the recess 327a is formed at the position C of one face in the thickness direction of the plurality of core plates 325 and the projection 327b is formed at the position C of the other face in the thickness direction by pressing the plurality of core plates 325 in the thickness direction. In addition, in the rivet portion forming process, the projection fixing through-hole 327c is formed at the position C in the core plate 325b.

[0134] In the present embodiment, after the rivet portions 327 are formed on the plurality of core plates 325 by the rivet portion forming process, a stacking process of stacking the plurality of core plates 325 is performed. That is, in the stacking process of stacking the plurality of core plates 325, one core plate 325 and the other core plate 325 are connected in the stacking direction by fitting the projection 327b of the other core plate 325 in the recess 327a of one core plate 325 adjacent in the stacking direction.

[0135] Thus, in the present embodiment, the plurality of core plates 325 can be connected while being stacked. Therefore, compared with a manufacturing method including a process of connecting the plurality of core plates 325 in the stacking direction in addition to a process of stacking the plurality of core plates 325, the manufacturing efficiency of the rotor 302 can be improved.

[0136] In addition, in the stacking process, for each core plate 325 constituting one rotor core 321, the core plate 325b in which the projection fixing through-hole 327c is formed is stacked. Thus, the rotor core 321 in which a predetermined number of the plurality of core plates 325 are stacked can be easily manufactured.

[0137] (Other Embodiments) The above describes the embodiments of the present application, but the above embodiments are merely one example for implementing the present application. Therefore, the present application is not limited to the above embodiments, but can be appropriately modified within the spirit of the embodiments.

[0138] In each of the above-described embodiments, the rotor 2, 102, 202, 302 has one rotor core 21, 121, 221, 321. However, a rotor block RB having the same structure as the rotor described in each of the above-described embodiments can be stacked in the axial direction to constitute the rotor.

[0139] For example, as shown in FIG. 4, in the rotor 402, four rotor blocks RB having the same structure as the rotor 2 of the first embodiment are stacked in the axial direction. Of the four rotor blocks RB, the circumferential position of the magnets 22 of a part of the rotor blocks RB is different from the position of the magnets 22 of the other rotor blocks RB when viewed in the above-described axial direction. Figure 21

[0140] Specifically, if the four rotor blocks RB are, in order from one end portion to the other end portion of the rotor 402, the rotor block RB1, the rotor block RB2, the rotor block RB3, and the rotor block RB4, the position of the magnets 22 in the rotor block RB1 is different from the position of the magnets 22 in the rotor block RB2 when viewed in the above-described axial direction. The position of the magnets 22 in the rotor block RB3 is different from the position of the magnets 22 in the rotor block RB4 when viewed in the above-described axial direction.

[0141] In this way, by configuring a part of the magnets 22 to be circumferentially offset with respect to the other magnets 22 when viewed in the above-described axial direction, it is possible to disperse the attraction force of the rotor 402 to the stator. Therefore, it is possible to reduce the cogging torque.

[0142] In the rotor core 21 of the above-described first embodiment and the second embodiment, the second core plate 7 is stacked on the rear side in the magnet insertion direction and the front side in the magnet insertion direction of one first core plate 6, 106. However, in the rotor core, a plurality of first core plates can be continuously stacked.

[0143] In the rotor core 221 of the above-described third embodiment, one third core plate 208 is stacked on the front side in the magnet insertion direction of one first core plate 206. However, in the rotor core, a third core plate can be stacked on the front side in the magnet insertion direction of a plurality of first core plates that are continuously stacked. In the rotor core, a plurality of third core plates can also be continuously stacked on the front side in the magnet insertion direction of the first core plate.

[0144] In each of the above-described embodiments, the magnets 22 have a cuboid shape. However, the magnets can also have other shapes other than a cuboid. The above-described magnets can be a shape that can be inserted into the magnet insertion hole and can be held by the protruding portion. For example, the magnets can be a polygonal prism other than a quadrangular prism.

[0145] ​In the above-described first embodiment, second embodiment, and fourth embodiment, the plurality of core plates 25, 125, 325 includes the first core plate 6, 106 and the second core plate 7. However, the plurality of core plates can include other core plates in addition to the first core plate and the second core plate. It is only necessary that the above-described other core plates have recesses at positions overlapping the protruding portions of the above-described first core plate when viewed from the above-described axis direction in a state in which the other core plates are laminated with the first core plate.

[0146] In the above-described third embodiment, the plurality of core plates 225 includes the first core plate 206, the second core plate 207, and the third core plate 208. However, the plurality of core plates can include other core plates in addition to the first core plate, the second core plate, and the third core plate. It is only necessary that the above-described other core plates have recesses at positions overlapping the protruding portions of the above-described first core plate when viewed from the above-described axis direction in a state in which the other core plates are laminated with the first core plate.

[0147] In the above-described first embodiment, the first core plate 6 has two protruding portions 62 with respect to one first insertion hole 61. However, the first core plate can have one protruding portion with respect to one first insertion hole. The first core plate can also have three or more protruding portions with respect to one first insertion hole.

[0148] In the above-described second embodiment, the first core plate 106 has two protruding portions 62 and two deformation permitting portions 163 with respect to one first insertion hole 61. However, the first core plate can have one protruding portion and one deformation permitting portion with respect to one first insertion hole. The first core plate can also have three or more protruding portions and deformation permitting portions with respect to one first insertion hole.

[0149] In the above-described first embodiment and second embodiment, the first core plate 6, 106 has the protruding portion 62 with respect to all of the first insertion holes 61. However, the first core plate can have the protruding portion with respect to a part of the first insertion holes.

[0150] In the above-described second embodiment, the first core plate 106 has the deformation permitting portion 163 with respect to all of the first insertion holes 61. However, the first core plate can have the deformation permitting portion with respect to a part of the first insertion holes.

[0151] In the above-described first embodiment and second embodiment, the second core plate 7 has the recess 72 at a position overlapping the protruding portion 62 of the first core plate 6, 106 when viewed in the axis direction. However, the second core plate can not have the recess at the position overlapping the protruding portion of the first core plate. The second core plate can have a protruding portion shorter in length in the protruding direction than the above-described first core plate at the position overlapping the protruding portion of the first core plate.

[0152] In each of the above embodiments, in the core sheet forming process, the protruding portions 62 are formed so as to protrude toward the interiors of the insertion holes 91 for all of the insertion holes 91. However, in the core sheet forming process, the protruding portions 62 can be formed so as to protrude toward the interiors of the insertion holes for a part of the insertion holes.

[0153] In each of the above embodiments, in the protruding portion removing process, the protruding portions 62 are punched at positions closer to the direction opposite to the protruding direction of the protruding portions than the base end portions of the protruding portions. However, the protruding portion removing process can punch the protruding portions at the base end portions of the protruding portions. The protruding portion removing process can punch the protruding portions between the base end portions and the front end portions of the protruding portions.

[0154] (Example of Configuration) In addition, the present technology can also employ the following structure.

[0155] (1) A manufacturing method of a rotor that includes a cylindrical rotor core having a plurality of core sheets stacked in a thickness direction and a plurality of magnet insertion holes extending in an axial direction, and a plurality of magnets each inserted into each of the plurality of magnet insertion holes. The manufacturing method of the rotor includes a core sheet forming process of punching a steel sheet to form a plurality of core sheets each having a plurality of insertion holes each penetrating the steel sheet in the thickness direction and each constituting a part of each of the plurality of magnet insertion holes, and a plurality of protruding portions each protruding toward an interior of each of the plurality of insertion holes; a protruding portion removing process of removing at least one of the plurality of protruding portions from at least some of the plurality of core sheets formed in the core sheet forming process; a stacking process of stacking the plurality of core sheets, so that the insertion holes from which the protruding portions protrude toward the interiors and the insertion holes from which the protruding portions are removed constitute the magnet insertion holes; and a magnet insertion process of inserting the magnets into each of the plurality of magnet insertion holes and holding the magnets in contact with the protruding portions.

[0156] (2) In the manufacturing method of the rotor described in (1), in the protruding portion removing process, the steel sheet is punched at a position closer to a direction opposite to a protruding direction of the protruding portion than a base end portion of the protruding portion, when the core sheet is observed in the thickness direction, so as to remove the protruding portion.

[0157] (3) In the manufacturing method of the rotor described in (1) or (2), further including a through-hole forming process of forming a through-hole in the steel sheet, the through-hole penetrating the steel sheet in the thickness direction to allow a part of the steel sheet to be deformed. In the core sheet forming process, the steel sheet in which the through-hole is formed by the through-hole forming process is punched to form a plurality of core sheets each having the plurality of insertion holes and the plurality of protruding portions.

[0158] (4) The rotor manufacturing method described in (3), wherein, in the protrusion removal step, protrusions of the plurality of protrusions that are not formed with the through hole at a position in the direction opposite to the direction in which the insertion hole is located in the arrangement direction of the protrusions are removed.

[0159] (5) The rotor manufacturing method described in (3), wherein, in the protrusion removal step, protrusions of the plurality of protrusions that are not formed with the through hole at a position in the direction opposite to the direction in which the insertion hole is located in the arrangement direction of the protrusions are all removed.

[0160] (6) The rotor manufacturing method described in (3), wherein, in the protrusion removal step, at least one protrusion of the plurality of protrusions that is formed with the through hole at a position in the direction opposite to the direction in which the insertion hole is located in the arrangement direction of the protrusions is removed, and at least one protrusion of the plurality of protrusions that is not formed with the through hole at the position in the opposite direction is removed.

[0161] (7) The rotor manufacturing method described in any one of (1) to (6), wherein, in the protrusion removal step, all of the protrusions of at least some of the plurality of core plates formed in the core plate formation step are removed. In the lamination step, the core plates with the plurality of protrusions and the core plates from which the plurality of protrusions are removed are laminated.

[0162] (8) The rotor manufacturing method described in any one of (1) to (7), further comprising a rivet formation step of pressing prescribed positions of the plurality of core plates in a thickness direction to form a recess at the prescribed position of one face in the thickness direction of the core plate and a protrusion at the prescribed position of the other face in the thickness direction. In the lamination step, the protrusion of one core plate is fitted into the recess of another core plate that is adjacent in the lamination direction among the plurality of core plates, thereby connecting the one core plate and the another core plate in the lamination direction.

[0163] (9) The rotor has a cylindrical rotor core having a plurality of core sheets stacked in a thickness direction and a magnet insertion hole extending in an axial direction, and a magnet inserted into the magnet insertion hole, the plurality of core sheets including a first core sheet and a second core sheet stacked on the first core sheet in the thickness direction. The first core sheet has a first insertion hole that penetrates the first core sheet in the thickness direction and constitutes a part of the magnet insertion hole, and a protruding portion that protrudes toward an inside of the first insertion hole and contacts the magnet. The second core sheet has a second insertion hole that penetrates the second core sheet in the thickness direction and constitutes a part of the magnet insertion hole, and a recessed portion on an inner surface constituting the second insertion hole, which is recessed toward a direction opposite to a protruding direction of the protruding portion of the first core sheet when the rotor core is viewed from the axial direction. On the inner surface of the second insertion hole, a connecting portion between an inner surface constituting the recessed portion and an inner surface constituting a portion other than the recessed portion is angular.

[0164] (10) In the rotor described in (9), the first core sheet has a deformation permitting portion that is located in a direction opposite to a direction in which the first insertion hole is located with respect to the protruding portion in an arrangement direction of the first insertion hole and the protruding portion, and permits the protruding portion to be deformed in the opposite direction.

[0165] (11) In the rotor described in (10), the deformation permitting portion is a through hole that penetrates the first core sheet in the thickness direction. Industrial applicability

[0166] The present application can be used for a rotor in which a magnet inserted into a magnet insertion hole is held by a portion of a core sheet. Explanation of symbols

[0167] 1 motor 2, 102, 202, 302, 402 rotor 2a shaft insertion hole 3 stator 4 housing 5 shaft 6, 106, 206 first core sheet 7, 207 second core sheet 21, 121, 221, 321 rotor core 21a, 21b, 121a, 221a, 321a, 321b end surface 22 magnet 25, 125, 225, 325 plurality of core sheets 26, 126, 226, 326 magnet insertion hole 31 stator core 32 stator coil 61 first insertion hole 61a, 61b inner surface 62 protruding portion 62a front end portion 71 second insertion hole 71a, 71b inner surface 71c connecting portion 72 recess 90 steel plate 91 insertion hole 93 through hole 163 deformation permitting portion 208 third core plate 263 first deformation permitting portion (deformation permitting portion) 272 second recess (recess) 281 third insertion hole 281a, 281b inner surface 282 third recess 283 third deformation permitting portion 325a, 325b, 325c core plate 327 clinching portion 327a recess 327b protrusion 327c protrusion fixing through hole B1, B2, B3 punch M1, M2, M3 die RB, RB1, RB2, RB3, RB4 rotor block W core plate

Claims

1. A method for manufacturing a rotor, the rotor comprising: a columnar rotor core having a plurality of core plates stacked along the thickness direction and a plurality of magnet insertion holes extending along the axial direction; and a plurality of magnets, each of which is inserted into a plurality of magnet insertion holes, characterized in that it includes: In the core plate forming process, a steel plate is punched to form multiple core plates. The core plate has multiple insertion holes and multiple protrusions. The multiple insertion holes penetrate the steel plate along the thickness direction and each constitutes part of the multiple magnet insertion holes. The multiple protrusions protrude toward the interior of the multiple insertion holes. The protrusion removal process removes at least one of the protrusions from at least a portion of the multiple core plates formed in the core plate forming process. In a stacking process, the plurality of core boards are stacked, thereby forming the magnet insertion hole by the insertion hole protruding inward from the protrusion and the insertion hole without the protrusion; and In the magnet insertion process, the magnet is inserted into each of the plurality of magnet insertion holes and the magnet is brought into contact with the protrusion to hold the magnet.

2. The rotor manufacturing method according to claim 1, characterized in that, In the protrusion removal process... When the core plate is viewed from the thickness direction, the steel plate is punched at a position further than the base end of the protrusion and in the opposite direction to the protrusion of the protrusion, thereby removing the protrusion.

3. The rotor manufacturing method according to claim 1 or 2, characterized in that, It also includes a through-hole forming process, in which a through-hole is formed in the steel plate, the through-hole penetrating the steel plate in the thickness direction to allow for deformation of a portion of the steel plate. In the core board forming process, The steel plate, having formed the through hole through the through hole forming process, is punched to form a plurality of core plates, each core plate having a plurality of insertion holes and a plurality of protrusions.

4. The rotor manufacturing method according to claim 3, characterized in that, In the protrusion removal process... Remove the protrusions that do not form the through hole in the direction opposite to the direction of the insertion hole in the arrangement direction of the protrusions.

5. The rotor manufacturing method according to claim 3, characterized in that, In the protrusion removal process... Remove all protrusions that do not form the through hole in the direction opposite to the direction of the insertion hole in the arrangement direction of the protrusions.

6. The rotor manufacturing method according to claim 3, characterized in that, In the protrusion removal process... Remove at least one of the plurality of protrusions that has the through hole formed in the direction opposite to the direction of the insertion hole in the arrangement direction of the protrusions, and remove at least one of the plurality of protrusions that does not have the through hole formed in the opposite direction.

7. The rotor manufacturing method according to claim 1 or 2, characterized in that, In the protrusion removal process... Remove all protrusions from at least a portion of the core boards formed in the core board forming process. In the lamination process, The core plate having the plurality of protrusions and the core plate having the plurality of protrusions removed are stacked together.

8. The rotor manufacturing method according to claim 1 or 2, characterized in that, It also includes a riveting part forming process, which involves pressing the plurality of core plates at predetermined positions along the thickness direction to form a recess at the predetermined position on one side of the core plate in the thickness direction and a protrusion at the predetermined position on the other side of the thickness direction. In the lamination process, In the plurality of core boards, a protrusion of another core board is fitted into a recess of an adjacent core board along the stacking direction, thereby connecting the one core board to the other core board along the stacking direction.

9. A rotor having: A columnar rotor core having multiple core plates stacked along the thickness direction and a magnet insertion hole extending along the axial direction; as well as A magnet, which is inserted into the magnet insertion hole. The plurality of core boards include: First core board; and The second core board is stacked on top of the first core board along its thickness direction. Its features are, The first core board has: A first insertion hole, which penetrates the first core plate along its thickness direction and forms part of the magnet insertion hole; and A protrusion that protrudes toward the interior of the first insertion hole and contacts the magnet. The second core board has: A second insertion hole, which penetrates the second core plate along its thickness direction and forms part of the magnet insertion hole; and A recess is located on the inner surface forming the second insertion hole, and when the rotor core is viewed from the axial direction, it is recessed in a direction opposite to the protruding direction of the protrusion of the first core plate. On the inner surface of the second insertion hole, the connection between the inner surface forming the recess and the inner surface forming the portion other than the recess is at an angle.

10. The rotor according to claim 9, characterized in that, The first core plate has a deformation-allowing portion located in the opposite direction to the direction in which the first insertion hole is positioned relative to the protrusion in the arrangement direction of the first insertion hole and the protrusion, and allowing the protrusion to deform in the opposite direction.

11. The rotor according to claim 10, characterized in that, The deformation-allowing portion is a through hole that penetrates the first core plate along the thickness direction.

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