Manufacturing method of laminated core, laminated core, fitting method between laminated core and shaft, and fitting structure between laminated core and shaft

Abstract

To reduce adhesion when a shaft is pressed into a laminated core and damage to the insulating coating of electromagnetic steel sheets that accompany a crimping process between the electromagnetic steel sheets that make up the laminated core, thereby reducing an eddy current loss and improving the fitting strength and centering accuracy between the laminated core and the shaft.SOLUTION: A first core is formed by stacking a plurality of first electromagnetic steel plates to form a first through hole, and a second core is formed by stacking second electromagnetic steel plates having second insertion holes and first protrusions that are spaced apart from each other and protrude inward from the periphery of the second insertion holes on at least one end face of the first core such that the first insertion holes and the second insertion holes are coaxially connected to each other to form a common insertion hole that is a single insertion hole, a laminated core is formed using one or more second cores, the first protrusions are bent to form a first bent portion, and a shaft is pressed into the common insertion hole to clamp the shaft by the inner surface of the first bent portion.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a laminated core, a laminated core, a method for fitting a laminated core to a shaft, and a structure for fitting a laminated core to a shaft. [Background technology]

[0002] Conventionally, laminated cores formed by laminating electromagnetic steel sheets having insulating coatings are used as cores for rotating electric machines such as generators and electric motors. Such laminated cores are formed by laminating a plurality of electromagnetic steel sheets each having a rotating shaft insertion hole, aligning the plates so that the rotating shaft insertion holes are arranged coaxially. Then, a shaft (rotating shaft) is press-fitted into the rotating shaft insertion hole of the laminated core.

[0003] Each of the electromagnetic steel sheets constituting the laminated core is often formed by punching a strip-shaped sheet material by press working. However, the cross section punched by such punching work (hereinafter, may be referred to as the "punched surface") is work-hardened. Therefore, work hardening also occurs on the inner peripheral surface of the rotating shaft insertion hole. As a result, the hardness of the work-hardened portion of the rotating shaft insertion hole becomes higher than the hardness of the shaft, and there is a risk of adhesion occurring when the shaft is press-fitted into the rotating shaft insertion hole. The occurrence of such adhesion (hereinafter, may be referred to as "press-fitting adhesion") adversely affects the centering accuracy of the laminated core.

[0004] Also, as described in Patent Document 1 (JP 2008-036671 A), for example, in laminated cores, electromagnetic steel sheets are generally bound and fixed together by means of crimping or the like. However, if a part of the electromagnetic steel sheet is sheared by the crimping and the insulating coating is broken, the sheared surfaces of the electromagnetic steel sheets may come into contact with each other. In such a case, a short circuit may occur, causing eddy current loss when used as a core for a rotating electric machine or the like, and the expected component performance may not be achieved.

[0005] Therefore, Patent Document 2 (JP Patent Publication 2010-110123 A) discloses a technique in which a burring portion is formed on the periphery of a rotating shaft insertion hole of one of a plurality of stacked electromagnetic steel sheets, the burring portion is inserted into the rotating shaft insertion hole of the other electromagnetic steel sheets, and a shaft is inserted into the burring portion. According to this technique, the burring portion (cylindrical portion) is slightly expanded in diameter to be brought into close contact with the inner peripheral surface of the rotating shaft insertion hole of the other electromagnetic steel sheets, thereby fixing the plurality of electromagnetic steel sheets. Therefore, it is possible to omit bundling and fixing the electromagnetic steel sheets together by crimping, and therefore it is possible to prevent short-circuiting of the electromagnetic steel sheets caused by crimping. In addition, it is possible to avoid direct contact between the shaft and the inner peripheral surface of the rotating shaft insertion hole where work hardening and breakage of the insulating coating caused by punching have occurred, and therefore it is possible to prevent adhesion and short-circuiting of the electromagnetic steel sheets through the shaft when the shaft is pressed into the rotating shaft insertion hole.

[0006] However, since the burring portion (cylindrical portion) is formed by pressing the material (wall) constituting the peripheral portion of the portion that will become the rotary shaft insertion hole with a punch and bending it all around, it is assumed that the circumferential length and / or wall thickness of the peripheral portion will change. Therefore, it is difficult to avoid problems such as cracks, wrinkles, and / or thinning (which is in conflict with the height of the burring portion) in the burring portion, and it is difficult to precisely control the shape and thickness of the burring portion. Furthermore, since there is variation in the thickness of the material of the electromagnetic steel sheet itself (e.g., a strip-shaped plate material, etc.), it becomes even more difficult to precisely control the thickness of the burring portion. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2008-036671 A [Patent Document 2] JP 2010-110123 A Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, in this technical field, there is a need for a technology that can reduce eddy current loss by reducing adhesion when a shaft is pressed into an insertion hole formed in a laminated core and rupture of the insulating coating of the electromagnetic steel sheets that are involved in crimping the electromagnetic steel sheets that make up the laminated core, while also improving the fitting strength and centering accuracy between the laminated core and the shaft. [Means for solving the problem]

[0009] Therefore, as a result of intensive research, the inventors discovered that the above problem can be solved by providing multiple protrusions that protrude inward from the periphery of the insertion hole in some of the multiple electromagnetic steel sheets that make up the laminated core, and then bending the protrusions to form bent portions and then pressing the shaft into them.

[0010] Specifically, the method for producing a laminated core according to the present invention is a method for producing a laminated core formed by laminating a plurality of electromagnetic steel sheets each having an insertion hole, and includes a first lamination step, a second lamination step, and a bending step, which are described below.

[0011] The first lamination step is a step of forming a first core by laminating a plurality of first electromagnetic steel sheets having first insertion holes such that the first insertion holes are coaxially connected to one another.

[0012] The second lamination process is a process for forming a second core by laminating a second electromagnetic steel sheet having a second insertion hole and a plurality of first protrusions spaced apart from each other and protruding inward from the periphery of the second insertion hole on at least one end face of the first core. As a result, the first insertion hole and the second insertion hole are coaxially connected to each other to form a common insertion hole. A laminated core is formed by one second core thus formed or by a plurality of second cores stacked such that the common insertion holes of adjacent second cores are coaxially connected to each other.

[0013] The bending step is a step of bending the plurality of first protruding portions along the direction of a common axis that is the central axis of the common insertion hole to form a plurality of first bent portions.

[0014] The laminated core according to the present invention is a laminated core formed by laminating a plurality of electromagnetic steel sheets having insertion holes, and is composed of a plurality of second cores laminated so that the common insertion holes of one second core or adjacent second cores are coaxially connected to each other. The second core is formed by laminating a second electromagnetic steel sheet having a second insertion hole on at least one end surface of a first core formed by laminating a plurality of first electromagnetic steel sheets having a first insertion hole so that the first insertion holes are coaxially connected to each other. In the second core, the first insertion hole and the second insertion hole are coaxially connected to each other to form a common insertion hole that is one insertion hole. Furthermore, the second electromagnetic steel sheet has a plurality of first bent portions that are bent at the periphery of the second insertion hole and extend in the direction of a common axis that is the central axis of the common insertion hole.

[0015] Furthermore, a method of fitting a laminated core and a shaft according to the present invention is a method of fitting a laminated core and a shaft by press-fitting the shaft into the common insertion hole of the laminated core according to the present invention. The method of fitting a laminated core and a shaft according to the present invention includes a press-fitting step of press-fitting the shaft into the common insertion hole to sandwich the shaft between the first inner circumferential surfaces of the first bent portions, which are surfaces facing the common insertion hole.

[0016] In addition, the fitting structure between the laminated core and the shaft according to the present invention is a fitting structure between the laminated core and the shaft in which the shaft is press-fitted into the common through-hole of the laminated core according to the present invention. In the fitting structure between the laminated core and the shaft according to the present invention, the shaft is sandwiched between the first inner peripheral surfaces, which are the surfaces facing the common through-hole of the first bent portions. Effect of the Invention

[0017] As described above, in the manufacturing method of the laminated core according to the present invention, instead of expanding the diameter of the burring portion to make it adhere closely to the inner peripheral surface of the insertion hole as in the above-mentioned conventional technology, the multiple first protrusions protruding inward from the periphery of the second insertion hole of the second electromagnetic steel sheet are bent to form multiple first bent portions extending in the direction of the common axis that is the central axis of the common insertion hole. In the fitting method of the laminated core and the shaft according to the present invention, the shaft is press-fitted into the common insertion hole of the laminated core according to the present invention, and the shaft is clamped by the multiple first inner peripheral surfaces that are the surfaces of the multiple first bent portions facing the common insertion hole.

[0018] As described above, according to the fitting structure between the laminated core and the shaft of the present invention, by press-fitting the shaft into the common insertion hole, not only the fitting between the laminated core and the shaft but also the binding and fixing between the first electromagnetic steel sheets and the first electromagnetic steel sheets and the second electromagnetic steel sheets constituting the laminated core can be achieved. Therefore, the binding and fixing between the electromagnetic steel sheets by the crimping process can be reduced, and therefore the short circuit of the electromagnetic steel sheets caused by the crimping process can be reduced.

[0019] Furthermore, in the fitting structure between the laminated core and the shaft according to the present invention, a first bent portion is interposed between the shaft and the inner circumferential surface of the insertion hole of the first electromagnetic steel sheet, and an insulating coating is present on the outer circumferential surface of the first bent portion facing the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet. Therefore, even if work hardening and rupture of the insulating coating due to punching occur on the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet, contact between the shaft and the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet is avoided, thereby reducing the occurrence of adhesion and short-circuiting of the first electromagnetic steel sheet through the shaft when the shaft is pressed into the common insertion hole.

[0020] In addition, since the first bent portion that holds the shaft to be pressed in is formed by bending the first protrusion made of the steel plate that constitutes the second electromagnetic steel plate, the dimensional accuracy of the plate thickness, height, etc. is higher than that of the burring portion in the conventional technology described above. As a result, the press-fitting allowance of the shaft into the common insertion hole can be guaranteed, so that the centering accuracy can be improved and the fitting strength can be ensured.

[0021] In addition, since the first bent portions are arranged intermittently and not all around the circumference, and are formed by bending the first protruding portion, problems such as cracks, wrinkles, and / or thinning (which is contrary to the height of the burred portion) that are a concern in the burred portion of the conventional technology can be reduced. Furthermore, since the plate thickness of the first bent portion is uniform and the first inner peripheral surface is smooth compared to the burred portion of the conventional technology, even though the first bent portions are arranged intermittently and not all around the circumference, the first inner peripheral surface of the first bent portion and the shaft can be in surface contact with each other with a sufficient effective contact area. Therefore, reliable torque transmission can be achieved.

[0022] In other words, according to the present invention, adhesion when a shaft is pressed into a common insertion hole formed in a laminated core and rupture of the insulating coating of the electromagnetic steel sheets that accompany crimping of the electromagnetic steel sheets that make up the laminated core can be reduced, thereby reducing eddy current loss, and the fitting strength and centering accuracy between the laminated core and the shaft can be improved.

[0023] Other objects, features and attendant advantages of the present invention will become readily apparent from the following description of the embodiments of the present invention which are given with reference to the accompanying drawings. [Brief description of the drawings]

[0024] [Figure 1] 4 is a flowchart illustrating the flow of each step included in the manufacturing method (first manufacturing method) of the laminated core according to the first embodiment of the present invention. [Diagram 2]1A is a schematic plan view illustrating the configuration of a first electromagnetic steel sheet, and FIG. 1B is a schematic perspective view illustrating the configuration of a first core formed by performing a first lamination step. [Diagram 3] 6A is a schematic plan view illustrating the configuration of a second electromagnetic steel sheet, and FIG. 6B is a schematic perspective view illustrating the configuration of a second core formed by performing a second lamination step. [Figure 4] FIG. 2A is a schematic perspective view illustrating a configuration of a laminated core formed of a plurality of second cores, and FIG. 2B is a schematic cross-sectional view of the laminated core. [Diagram 5] 1A is a schematic perspective view illustrating the configuration of a laminated core in which a bent portion is formed by performing a bending process, and FIG. 1B is a schematic cross-sectional view of the laminated core. [Figure 6] 5A to 5C are schematic cross-sectional views illustrating a state in which a shaft is press-fitted into a common insertion hole of a laminated core manufactured by the first manufacturing method. [Figure 7] FIG. 7 is a schematic enlarged view of a portion circled by a thick dashed line in FIG. 6(a). [Figure 8] 13A and 13B are schematic plan views illustrating configurations of first protruding portions provided on second electromagnetic steel sheets according to modified examples. [Figure 9] 6 is a flowchart illustrating the flow of each step included in a manufacturing method (second manufacturing method) for a laminated core according to a second embodiment of the present invention. [Figure 10] 6 is a schematic diagram illustrating the configuration of a second electromagnetic steel sheet employed in the second manufacturing method. FIG. [Figure 11] 10A to 10C are schematic cross-sectional views illustrating the configuration of a second core constituting a laminated core obtained as a result of performing a bending step included in a second manufacturing method. [Figure 12] 13A to 13C are schematic plan views illustrating the configuration of a first electromagnetic steel sheet having a polygonal insertion hole employed in a manufacturing method (third manufacturing method) for a laminated core according to a third embodiment of the present invention. [Figure 13] 13A to 13C are schematic diagrams illustrating the configuration of a laminated core formed by performing a second lamination step included in the third manufacturing method. [Figure 14]14A to 14C are schematic diagrams illustrating the configuration of a laminated core formed from the laminated core illustrated in FIG. 13 by performing a bending step included in the third manufacturing method. [Figure 15] 13 is a schematic plan view illustrating the configuration of a first electromagnetic steel sheet having a star-shaped polygonal through-hole employed in the third manufacturing method. FIG. [Figure 16] 13 is a schematic perspective view illustrating the configuration of a laminated core having a star-shaped polygonal common insertion hole formed by performing a bending process included in the third manufacturing method, and a shaft having a corresponding star-shaped polygonal cross section. FIG. [Figure 17] 17 is a schematic plan view illustrating the configuration of a first electromagnetic steel sheet and a second electromagnetic steel sheet having a substantially star-shaped regular octagonal through-hole that constitute the laminated core illustrated in FIG. 16(a). FIG. [Figure 18] 17A is a schematic cross-sectional view of the laminated core illustrated in FIG. 16A taken along a plane parallel to the common axis and passing through the straight line FF; FIG. 17A is a schematic arrow view of the laminated core as viewed from the direction of arrow G shown in FIG. 17A; and FIG. 17B is a schematic enlarged view showing a state in which a shaft is pressed into a common insertion hole of the laminated core and a first bent portion is sandwiched between the laminated core and the shaft. [Figure 19] 13 is a schematic perspective view illustrating the configuration of a first core formed by laminating first electromagnetic steel sheets, which is employed in a manufacturing method (fourth manufacturing method) for a laminated core according to a fourth embodiment of the present invention. FIG. [Figure 20] 13 is a schematic diagram showing a state in which a first bent portion is partially immersed in a recess formed on an inner circumferential surface of a first insertion hole in a fitting structure between a laminated core and a shaft manufactured by a fourth manufacturing method. FIG. [Figure 21] 13A to 13C are schematic plan views illustrating the configurations of first and second electromagnetic steel sheets having polygonal insertion holes employed in a manufacturing method (fifth manufacturing method) for a laminated core according to a fifth embodiment of the present invention. [Figure 22] 22A and 22B are schematic perspective and top views illustrating the configuration of a laminated core formed from the first and second electromagnetic steel sheets illustrated in FIG. 21 . [Diagram 23]22(a) is a schematic arrow view of the laminated core illustrated in FIG. 22(a) when viewed from the direction of arrow I shown in FIG. 22(b), and a schematic enlarged view of a portion where a shaft is pressed into a common insertion hole of the laminated core illustrated in FIG. 22(a) and a key provided in the laminated core is accommodated in a key groove provided in the shaft. [Figure 24] 13A to 13C are schematic diagrams showing one example of the configuration of a laminated core formed by performing a folding step included in the manufacturing method (sixth manufacturing method) of a laminated core according to a sixth embodiment of the present invention. [Diagram 25] 25 is a schematic plan view showing one example of the configuration of two types of first electromagnetic steel sheets that form the laminated core illustrated in FIG. 24. [Figure 26] 13 is a schematic diagram showing another example of the configuration of a laminated core formed by performing the folding step included in the sixth method. FIG. [Figure 27] 27 is a schematic plan view showing one example of the configuration of two types of first electromagnetic steel sheets that form the laminated core illustrated in FIG. 26. FIG. [Figure 28] 13A to 13C are schematic diagrams illustrating the configuration of a laminated core formed by performing a bending step included in the sixth manufacturing method applied to the second manufacturing method. [Figure 29] 13A to 13C are schematic views illustrating the state of the laminated core at the time when the bending step is completed in the case where the manufacturing method for the laminated core according to the seventh embodiment of the present invention (eighth manufacturing method) is applied to the third manufacturing method. [Diagram 30] 30 is a schematic cross-sectional view illustrating a lamination state of first, second and third electromagnetic steel sheets in the laminated core illustrated in FIG. 29. [Diagram 31] 13 is a schematic perspective view illustrating the configuration of a laminated core formed by a sixth manufacturing method to which a seventh manufacturing method is applied. FIG. [Diagram 32] 31(a) and 31(b) is a schematic view taken along an arrow U in FIG. 31(e). [Diagram 33] 31(c) and (d) is a schematic view taken along an arrow U in FIG. 31(e). [Diagram 34] 1 is a flowchart illustrating the flow of each step when a press-fitting step included in a method of fitting a laminated core and a shaft according to a fifteenth embodiment of the present invention (first fitting method) is performed consecutively after any of the methods of manufacturing a laminated core according to a first embodiment of the present invention (first manufacturing method) to the method of manufacturing a laminated core according to a fourth embodiment of the present invention (fourth manufacturing method). [Diagram 35] 1 is a flowchart illustrating the flow of each step when the striking and pressing steps included in the method of fitting a laminated core and a shaft according to the seventeenth embodiment of the present invention (third fitting method) are performed consecutively after any of the methods of manufacturing a laminated core according to the first embodiment of the present invention (first manufacturing method) to the method of manufacturing a laminated core according to the fourth embodiment of the present invention (fourth manufacturing method). [Diagram 36] 13A to 13C are schematic views illustrating changes in the first inner circumferential surface accompanying execution of a squeezing step included in the third fitting method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] First Embodiment Hereinafter, a method for producing a laminated core according to a first embodiment of the present invention (hereinafter, may be referred to as a "first production method") will be described with reference to the drawings.

[0026] <composition> The first manufacturing method is a manufacturing method for a laminated core formed by laminating a plurality of electromagnetic steel sheets having insertion holes.

[0027] The configuration and material of the electromagnetic steel sheets constituting the laminated core, which is a laminated body serving as a core of a rotating electric machine, etc., are not particularly limited as long as they can perform the intended function as a core of a rotating electric machine, etc., and can withstand the environment during manufacture and use of the rotating electric machine, etc. The cross-sectional shape of the insertion hole of the laminated core is not particularly limited as long as it is possible to reduce slippage in the rotational direction between the laminated core and a shaft inserted into the insertion hole and fitted with the laminated core, and may be circular or non-circular. Specific examples of non-circular cross sections include not only rotationally symmetric shapes such as ellipses and polygons, but also shapes that are not rotationally symmetric. Furthermore, shapes with a part of a circle missing are also included in the non-circular shape.

[0028] The material constituting the shaft is not particularly limited as long as it can withstand the environment during manufacturing and use of the rotating electric machine, etc., and can be appropriately selected from various materials. In general, the material constituting the shaft is a metal such as steel, typically stainless steel. A hollow shaft may also be used for the purpose of, for example, weight reduction. Since the shaft is press-fitted into the insertion hole formed in the laminated core, the cross-sectional shape of the shaft is similar to the shape of the insertion hole. Furthermore, since the laminated core and the shaft need to be firmly fitted together by press-fitting into the insertion hole, the cross-sectional shape of the shaft is slightly larger than the shape of the insertion hole. That is, the cross-sectional shape of the shaft is designed so that a predetermined press-fit allowance (tightening allowance) can be achieved with respect to the insertion hole.

[0029] Fig. 1 is a flow chart illustrating the flow of each step included in the first manufacturing method. As illustrated in Fig. 1, the first method includes a first lamination step, a second lamination step, and a folding step, which are listed below. Figs. 2 to 5 are schematic diagrams illustrating the state of each component member in the first lamination step, the second lamination step, and the folding step, respectively.

[0030] The first lamination process executed in step S10 of the flow chart illustrated in FIG. 1 is a process of forming a first core 10 by laminating a plurality of first electromagnetic steel sheets 11 having first insertion holes 11a as illustrated in FIG. 2(a) so that the first insertion holes 11a are coaxially connected to each other as illustrated in FIG. 2(b). Note that FIG. 2(b) illustrates a specific number of first electromagnetic steel sheets 11 (three sheets in FIG. 2) as being laminated, but the number of first electromagnetic steel sheets 11 to be laminated is not limited to this example, and is appropriately determined, for example, according to a combination of the required thickness of the laminated core and the thickness of the first electromagnetic steel sheets 11. FIG. 2 also illustrates an example in which the cross-sectional shape of the first insertion hole is circular, but as described above, the cross-sectional shape of the insertion hole of the laminated core is not particularly limited as long as it is possible to reduce slippage in the rotational direction between the laminated core and the shaft, so the cross-sectional shape of the first insertion hole is also not limited to a circular shape. The same applies to FIGS. 3 to 5.

[0031] Next, the second lamination process executed in step S20 is a process of forming a second core 20 by laminating a second electromagnetic steel sheet having a second insertion hole 21a and a plurality of (eight in FIG. 3) first protrusions 21p spaced apart from each other and protruding inward from the periphery of the second insertion hole 21a, as illustrated in FIG. 3(a), on at least one end face of the first core 10. As a result, the first insertion hole 11a and the second insertion hole 21a illustrated in FIG. 2 are coaxially connected to each other to form a common insertion hole. A laminated core 30 is formed by one second core 20 thus formed or by a plurality of second cores 20 laminated such that the common insertion holes of adjacent second cores 20 are coaxially connected to each other. In addition, Fig. 3 shows an example in which the cross-sectional shape of the second insertion hole is circular, but as described above, the cross-sectional shape of the insertion hole of the laminated core is not particularly limited as long as it can reduce slippage between the laminated core and the shaft in the rotational direction, so the cross-sectional shape of the second insertion hole is also not limited to a circle. The same applies to Figs. 4 and 5.

[0032] In the example shown in FIG. 3(b), the laminated core 30 is formed by one second core 20 formed as described above. On the other hand, in the example shown in FIG. 4, the laminated core 30 is formed by two second cores 20 laminated so that the common insertion holes of adjacent second cores 20 communicate with each other coaxially. FIG. 4(a) is a schematic perspective view showing the entire laminated core 30, and FIG. 4(b) is a schematic cross-sectional view of the laminated core 30 taken along a plane passing through the straight line AA shown in FIG. 4(a) and parallel to the common axis that is the central axis of the common insertion hole. As illustrated in FIG. 4, in the second electromagnetic steel sheet 21, a plurality of (eight in FIG. 4) first protrusions 21p spaced apart from each other protrude inward from the periphery of the second insertion hole 21a. Incidentally, the number of laminations of the first electromagnetic steel sheets 11 constituting the first core 10 differs between (a) and (b) of FIG. 4, but these should be understood as illustrating variations of the first core 10.

[0033] However, the first lamination step and the second lamination step do not necessarily have to be performed separately as described above. For example, when the laminated core 30 is formed by one second core 20, the first electromagnetic steel sheets 11 and the second electromagnetic steel sheets 21 in the number required to form the first core 10 may be laminated simultaneously to form one second core 20 as the laminated core 30. On the other hand, when the laminated core 30 is formed by a plurality of second cores 20, the laminated core 30 may be formed by simultaneously and alternately laminating a set of the first electromagnetic steel sheets 11 in the number required to form the first core 10 and the second electromagnetic steel sheets 21.

[0034] The radial length of the first protrusions 21p of the second electromagnetic steel sheet 21 can be appropriately determined according to the number of first electromagnetic steel sheets 11 to be bound and fixed by the first protrusions 21p. The number and arrangement of the first protrusions 21p of the second electromagnetic steel sheet 21 are not particularly limited, but in view of the use as a core of a rotating electric machine or the like, it is preferable that all of the first protrusions 21p are arranged rotationally symmetrically around a common axis or at equal intervals around the common axis.

[0035] Next, the bending process executed in step S30 is a process in which, for example, a punch or the like having a cross-sectional shape corresponding to the cross-section of the common insertion hole is inserted into the common insertion hole, and thereby the multiple first protrusions 21p are bent along the direction of the common axis, which is the central axis of the common insertion hole, to form multiple first bent portions 21b, as illustrated in FIG. 5.

[0036] Fig. 5 is a schematic diagram illustrating the state of the laminated core when the bending process is completed, where (a) of Fig. 5 is a schematic perspective view, and (b) of Fig. 5 is a schematic cross-sectional view taken along a plane that passes through a straight line BB illustrated in (a) of Fig. 5 and is parallel to the central axis (common axis) of the common insertion hole. As illustrated in Fig. 5, a plurality of first protrusions 21p are bent in the direction of the common axis to form a plurality of first bent portions 21b.

[0037] In the laminated core 30 illustrated in FIG. 5, the first bent portions 21b are in close contact with the inner peripheral surface of the first insertion hole 11a (i.e., the inner peripheral surface of the insertion hole of the first core 10). As a result, the first core 10 formed by laminating the first electromagnetic steel sheets 11 and the second electromagnetic steel sheets 21 are bound and fixed together to form the second core 20. On the other hand, the second cores 20 constituting the laminated core are not bound and fixed together by the first bent portions 21b. Therefore, the adjacent second cores 20 may be bound and fixed together by means of, for example, crimping. However, even in such a case, the number of places where crimping is performed can be significantly reduced compared to the laminated core according to the conventional technology, so that short circuits between the electromagnetic steel sheets can be reduced and eddy current loss can be reduced when used as a core for a rotating electric machine or the like.

[0038] However, as will be described later in the description of other embodiments of the present invention, it is sufficient that at least a partial region of the multiple first bent portions 21b is in close contact with the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet 11 when the shaft is press-fitted into the common insertion hole. That is, at the time when the bending process is completed, the entire multiple first bent portions 21b may be in close contact with the inner circumferential surface of the insertion hole of the first core 10 as in the laminated core 30 illustrated in Fig. 5, or a portion of the multiple first bent portions 21b may be in close contact with the inner circumferential surface of the insertion hole of the first core 10, or the multiple first bent portions 21b may not be in close contact with the inner circumferential surface of the insertion hole of the first core 10 at all.

[0039] For the laminated core manufactured by the first manufacturing method as described above, the shaft 40 can be pressed into the common through hole with a predetermined press-fitting allowance Mp as illustrated in Fig. 6(a) and the shaft 40 can be sandwiched by the first inner peripheral surfaces, which are the surfaces of the first bent portions 21b facing the common through hole, as illustrated in Fig. 6(b). As illustrated in Fig. 6(b), "the state in which the shaft 40 is sandwiched by the first inner peripheral surfaces, which are the surfaces of the first bent portions 21b facing the common through hole" is a state in which "the first bent portion 21b is interposed between the inner peripheral surface of the first through hole 11a and the outer peripheral surface of the shaft 40" and "the inner peripheral surface of the first through hole 11a and the outer peripheral surface of the shaft 40 are not in contact with each other."

[0040] Fig. 7 is a schematic enlarged view of a portion surrounded by a circle drawn by a thick dashed line in Fig. 6(a). As illustrated in Fig. 7, the first bent portion 21b that holds the shaft 40 pressed into the common insertion hole is formed by bending a protruding portion made of a steel plate that constitutes the second electromagnetic steel plate 21, and therefore has higher dimensional accuracy in plate thickness, height, and the like than the burring portion in the conventional technology described above. As a result, when the shaft 40 is pressed into the common insertion hole, an accurate and uniform press-fit allowance (Mp) can be guaranteed, and therefore high centering accuracy and fitting strength can be achieved.

[0041] As described above, the electromagnetic steel sheets constituting the laminated core are often formed by stamping out a strip-shaped sheet material using a press process. Therefore, the radial length and shape of the first protrusions of the second electromagnetic steel sheets need to be determined so that adjacent first protrusions do not interfere with each other.

[0042] Fig. 8 is a schematic plan view illustrating a configuration of a first protrusion provided on a second electromagnetic steel sheet according to a modified example that satisfies such requirements. The radial length of the first protrusion 22p provided on the second electromagnetic steel sheet 22 illustrated in Fig. 8(a) is restricted to a degree that adjacent first protrusions 22p do not interfere with each other. On the other hand, the shape of the tip of the first protrusion 23p provided on the second electromagnetic steel sheet 23 illustrated in Fig. 8(b) is chamfered so that adjacent first protrusions 23p do not interfere with each other (see the area surrounded by the thick dashed line).

[0043] By determining the radial length and shape of the first protrusions so that adjacent first protrusions do not interfere with each other as described above, the first protrusions can be easily and smoothly bent in the subsequent bending step to reliably form the first bent portions. Note that the shapes of the second insertion holes 22a and 23a formed in the second electromagnetic steel sheets 22 and 23, respectively, illustrated in Fig. 8 are substantially regular octagons.

[0044] <effect> As described above, in the manufacturing method of the laminated core according to the first embodiment of the present invention (first manufacturing method), instead of expanding the diameter of the burring portion to make it adhere closely to the inner peripheral surface of the insertion hole as in the above-mentioned conventional technology, the first protruding portions protruding inward from the periphery of the second insertion hole of the second electromagnetic steel sheet are bent to form the first bent portions extending in the direction of the common axis that is the central axis of the common insertion hole. Therefore, for example, as will be described later in the description of other embodiments of the present invention, in a fitting structure between the laminated core and the shaft, in which the shaft is press-fitted into the common insertion hole of the laminated core manufactured by the first manufacturing method, the shaft is sandwiched by the first inner peripheral surfaces that are the surfaces of the first bent portions that face the common insertion hole.

[0045] In the above fitting structure, by press-fitting the shaft into the common insertion hole, not only can the laminated core and the shaft be fitted together, but also the first electromagnetic steel sheets constituting the laminated core can be bound and fixed together and the first electromagnetic steel sheets and the second electromagnetic steel sheets can be bound and fixed together by the crimping process. Therefore, the binding and fixing of the electromagnetic steel sheets by the crimping process can be reduced, and short-circuiting of the electromagnetic steel sheets caused by the crimping process can be reduced.

[0046] Furthermore, in the above fitting structure, a first bent portion is interposed between the shaft and the inner circumferential surface of the insertion hole of the first electromagnetic steel sheet, and an insulating coating is present on the outer circumferential surface of the first bent portion facing the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet. Therefore, even if work hardening and breakage of the insulating coating caused by punching occur on the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet, contact between the shaft and the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet is avoided, thereby reducing the occurrence of adhesion and short-circuiting of the first electromagnetic steel sheet through the shaft when the shaft is pressed into the common insertion hole.

[0047] In addition, since the first bent portion that holds the shaft in the above fitting structure is formed by bending the first protrusion made of the steel plate that constitutes the second electromagnetic steel plate, the dimensional accuracy of the plate thickness, height, etc. is higher than that of the burring portion in the above-mentioned conventional technology. As a result, the press-fitting allowance of the shaft into the common insertion hole can be guaranteed, so that the centering accuracy can be improved and the fitting strength can be ensured.

[0048] In addition, since the first bent portions are arranged intermittently and not all around the circumference, and are formed by bending the first protruding portion, problems such as cracks, wrinkles, and / or thinning (which is contrary to the height of the burred portion) that are a concern in the burred portion of the conventional technology can be reduced. Furthermore, since the plate thickness of the first bent portion is uniform and the first inner peripheral surface is smooth compared to the burred portion of the conventional technology, even though the first bent portions are arranged intermittently and not all around the circumference, the first inner peripheral surface of the first bent portion and the shaft can be in surface contact with each other with a sufficient effective contact area. Therefore, reliable torque transmission can be achieved.

[0049] In other words, the first manufacturing method reduces adhesion when the shaft is pressed into the common insertion hole formed in the laminated core and rupture of the insulating coating of the electromagnetic steel sheets that accompany the crimping process between the electromagnetic steel sheets that make up the laminated core, thereby reducing eddy current loss and improving the fitting strength and centering accuracy between the laminated core and the shaft.

[0050] Second Embodiment A method for producing a laminated core according to a second embodiment of the present invention (hereinafter, may be referred to as a "second production method") will be described below with reference to the drawings.

[0051] As described above, in the first manufacturing method described above, the first bent portion that clamps the shaft has higher dimensional accuracy than the burring portion in the conventional technology described above. Therefore, the first inner peripheral surface, which is the inner peripheral surface of the first bent portion, can be in surface contact with the shaft with a sufficient effective contact area. As a result, according to the first manufacturing method, it is possible to improve the centering accuracy and ensure the fitting strength to achieve reliable torque transmission. However, depending on the application of a rotating electric machine or the like that has a fitting structure between a laminated core and a shaft manufactured by the first manufacturing method, there are cases where a higher torque transmission performance is required by ensuring a higher fitting strength.

[0052] <composition> Therefore, the second manufacturing method is the above-mentioned first manufacturing method, which is a manufacturing method of a laminated core, further including a partial bending step prior to the folding step. The partial bending step is a step of providing one or more first bent portions in at least a part of the first protruding portions, the first protruding portions being bent in the same direction or the opposite direction to the direction in which the first protruding portions are bent in the folding step to form the first bent portions.

[0053] FIG. 9 is a flow chart illustrating the flow of each step included in the second manufacturing method. The flow chart illustrated in FIG. 9 is the same as the flow chart illustrated in FIG. 1 referred to in the description of the first manufacturing method, except that step S15, in which a partial bending step is performed, is added between step S10, in which a first stacking step is performed, and step S20, in which a second stacking step is performed. Therefore, detailed description of the flow of each step included in the second manufacturing method is omitted, and the change in the first inner circumferential surface accompanying the execution of the partial bending step will be described below. Note that the order in which the partial bending step is performed is not limited to the above as long as it is performed before the folding step, and for example, the partial bending step may be performed before the first stacking step. Alternatively, it is theoretically possible to perform the partial bending step after the second stacking step, but from the viewpoint of ensuring good workability, it is preferable to perform the partial bending step before the second stacking step.

[0054] Fig. 10(a) is a schematic plan view illustrating the configuration of the second electromagnetic steel sheet 22 illustrated in Fig. 8(a), and Fig. 10(b) is a schematic cross-sectional view of the second electromagnetic steel sheet 22 taken along a plane passing through the straight line CC illustrated in Fig. 10(a) and perpendicular to the second electromagnetic steel sheet 22. As described above, after the first lamination step and the second lamination step are completed, in the bending step, the multiple first protrusions 22p provided on the second electromagnetic steel sheet 22 are bent at locations indicated by dashed dotted lines F1 toward the central axis (common axis) of the common insertion hole, to form multiple first bent portions (not shown).

[0055] FIG. 11(a) is a schematic cross-sectional view of the second core 20 constituting the laminated core at the time when the bending process is completed as described above, taken along a plane that passes through the straight line CC depicted in FIG. 10(a) and is parallel to the central axis (common axis) of the common through hole. The first protrusion 22p of the second electromagnetic steel sheet 22 illustrated in FIG. 10(b) does not have a bent portion on the way, and the cross section of the first protrusion 22p taken along the above plane is linear. Therefore, as illustrated in FIG. 11(a), the cross section of the first bent portion 22b formed by bending the first protrusion 22p is also linear. In addition, the entire first bent portion 22b can be easily brought into close contact with the inner peripheral surface of the first through hole of the first core 10 made of the first electromagnetic steel sheet 13. As described above, the plate thickness of the first bent portion 22b is uniform and the inner peripheral surface is smooth compared to the burring portion in the conventional technology. As a result, even though the first bent portion 22b is arranged intermittently rather than around the entire circumference, the inner surface of the first bent portion 22b can be in surface contact with the shaft (not shown) with a sufficient effective contact area, thereby achieving reliable torque transmission.

[0056] However, as described above, depending on the application, such as in a rotating electric machine having a fitting structure between a laminated core manufactured by the laminated core manufacturing method of the present invention and a shaft, it may be required to ensure a higher fitting strength and achieve higher torque transmission performance.

[0057] 10(c) and 10(d) are schematic cross-sectional views of the second electromagnetic steel sheet 22 subjected to the bending process included in the second manufacturing method, taken along a plane perpendicular to the second electromagnetic steel sheet 22 and passing through the straight line CC depicted in FIG. 10(a). In the example shown in FIG. 10(c), a bent portion F2 is provided in the middle of the first protruding portion 22p, which is a portion bent in the same direction as the direction in which the first protruding portions 22p are bent to form the first bent portions 22b in the bending process (hereinafter, this may be referred to as the "bending direction") (see the white arrow shown in FIG. 10(b)). On the other hand, in the example shown in FIG. 10(d), a bent portion F3 is provided in the middle of the first protruding portion 22p, which is a portion bent in the opposite direction to the above-mentioned bending direction.

[0058] 11(b) and (c) are schematic cross-sectional views of a second core constituting a laminated core obtained by performing a bending process on a second core composed of the second electromagnetic steel sheet 22 and the first electromagnetic steel sheet 13 illustrated in FIG. 10(c) and (d), respectively. When the first protruding portion 22p has a bent portion F2 bent in the same direction as the bending direction as illustrated in FIG. 10(c), when the first protruding portion 22p is bent in the bending direction in the bending process, a portion of the first protruding portion 22p on the tip side from the bent portion F2 first abuts against the inner circumferential surface of the insertion hole of the first core 10. At this time, the portion between the base end (F1) of the first protruding portion 22p and the bent portion F2 is separated (floated) from the inner circumferential surface of the insertion hole of the first core 10. Therefore, in the subsequent bending process, this raised portion is pressed, for example, by a punch or the like, toward the inner circumferential surface of the insertion hole of the first core 10. However, when the pressing force by the punch or the like is subsequently released, for example, the restoring force (repulsion force) of that portion of the first bent portion 22b causes that portion to separate (rise up) again from the inner circumferential surface of the insertion hole of the first core 10, as illustrated in (b) of FIG.

[0059] On the other hand, when the first protruding portion 22p is provided with a bent portion F3 bent in the direction opposite to the bending direction as illustrated in (d) of Fig. 10, the first protruding portion 22p is pressed by, for example, a punch or the like in the process of bending the first protruding portion 22p in the bending direction in the bending step, and the base end (F1) side of the first protruding portion 22p starts to abut against the inner circumferential surface of the insertion hole of the first core 10, and the portion of the first protruding portion 22p on the tip side of the bent portion F3 finally abuts against the inner circumferential surface of the insertion hole of the first core 10. After that, when the pressing force by, for example, a punch or the like is released, the restoring force (repulsion force) of the portion of the first bent portion 22b causes the portion to separate (float) from the inner circumferential surface of the insertion hole of the first core 10 as illustrated in (c) of Fig. 11.

[0060] In addition, a plurality of bent portions F2 bent in the same direction as the bending direction and / or a plurality of bent portions F3 bent in the opposite direction to the bending direction may be provided in one first protruding portion. In addition, any two or more of the first protruding portion provided with the bent portion F2 bent in the same direction as the bending direction, the first protruding portion provided with the bent portion F3 bent in the opposite direction to the bending direction, and the first protruding portion not provided with the bent portion F2 or the bent portion F3 may be mixed in one second electromagnetic steel sheet. Furthermore, any two or more of the first protruding portion provided with the bent portion F2 bent in the same direction as the bending direction, the first protruding portion provided with the bent portion F3 bent in the opposite direction to the bending direction, and the first protruding portion not provided with the bent portion F2 or the bent portion F3 may be mixed in one second core.

[0061] As described above, in the second manufacturing method, one or more bent portions are provided in at least a part of the first protruding portion 22p in the partial bending step. As a result, when the next bending step is completed, a portion separated (raised) from the inner peripheral surface of the insertion hole of the first core 10 is formed in the first bent portion 22b. Therefore, for example, when a shaft is pressed into the common insertion hole as described later in the description of another embodiment of the present invention, the portion is pressed toward the inner peripheral surface of the insertion hole of the first core 10 by the shaft, and the restoring force (repulsion force) of the portion acts in a direction to clamp the shaft. As a result, the shaft pressed into the common insertion hole of the laminated core is more firmly clamped by the surface (first inner peripheral surface) of the plurality of first bent portions 22b facing the common insertion hole on the inside in the radial direction.

[0062] <effect> As described above, in the second manufacturing method, one or more bent portions are provided in at least a part of the first protrusion in the partial bending process. As a result, when the next bending process is completed, the portion separated from the inner peripheral surface of the insertion hole of the first core is formed in the first bent portion. Therefore, for example, when a shaft is pressed into the common insertion hole as described later in the description of another embodiment of the present invention, the shaft presses the portion toward the inner peripheral surface of the insertion hole of the first core, and the restoring force of the portion acts in a direction to clamp the shaft. As a result, the shaft pressed into the common insertion hole of the laminated core is more firmly clamped by the first inner peripheral surfaces of the multiple first bent portions. That is, according to the second manufacturing method, a higher fitting strength can be ensured and a higher torque transmission performance can be achieved.

[0063] Third Embodiment Hereinafter, a method for producing a laminated core according to a third embodiment of the present invention (hereinafter, may be referred to as a "third production method") will be described with reference to the drawings.

[0064] The above-mentioned first and second manufacturing methods can reduce adhesion when the shaft is pressed into the insertion hole formed in the laminated core and rupture of the insulating coating of the electromagnetic steel sheets that are involved in crimping the electromagnetic steel sheets that make up the laminated core, thereby reducing eddy current loss, and can increase the fitting strength and centering accuracy between the laminated core and the shaft. Therefore, the first and second manufacturing methods can achieve higher torque transmission performance.

[0065] On the other hand, in the technical field, it is known that the shape of the insertion hole of the laminated core and the shape of the cross section of the shaft are polygonal, such as octagonal or hexagonal, for the purpose of reducing slippage between the laminated core and the shaft in the rotational direction. Furthermore, the shape of the insertion hole of the laminated core and the shape of the cross section of the shaft may be a star-shaped polygon, such as a star-shaped octagon or star-shaped hexagon. The manufacturing method of the present invention can also be applied to the manufacture of laminated cores having such polygonal or star-shaped polygonal insertion holes.

[0066] <composition> That is, the third manufacturing method is a manufacturing method for a laminated core according to the first or second manufacturing method described above, in which the shape of the common insertion hole is a polygon or a star-shaped polygon. Therefore, the shapes of the first insertion hole of the first electromagnetic steel sheet constituting the common insertion hole and the second insertion hole of the second electromagnetic steel sheet are also polygonal or star-shaped polygon. Furthermore, the first protrusion protrudes inward from a side on the periphery of the second insertion hole. In addition, in the bending process, the first protrusion is bent along the direction of the common axis, which is the central axis of the common insertion hole, to form a first bent portion so as to face a portion corresponding to a side of the inner peripheral surface of the first insertion hole (i.e., the inner peripheral surface of the insertion hole of the first core).

[0067] FIG. 12 is a schematic plan view illustrating the configuration of a first electromagnetic steel sheet having a polygonal insertion hole used in the third manufacturing method, and the shapes of the first insertion holes 13a to 18a of the first electromagnetic steel sheets 13 to 18 illustrated in (a) to (f) are octagonal, heptagonal, hexagonal, pentagonal, rectangular, and triangular, respectively. As illustrated in FIG. 12, in the third manufacturing method, a wide variety of polygons can be adopted as the shape of the first insertion hole of the first electromagnetic steel sheet, and a polygon corresponding to the shape of the first insertion hole is also adopted as the cross-sectional shape of the shaft (not shown). In addition, in consideration of the use as a core of a rotating electric machine, etc., these polygons are preferably regular polygons. In addition, the first electromagnetic steel sheets 13 to 18 illustrated in FIG. 12 are merely examples, and the shape of the first insertion hole of the first electromagnetic steel sheet used in the third manufacturing method is not limited to these.

[0068] FIG. 13 is a schematic diagram illustrating the configuration of a laminated core formed by performing the second lamination step included in the third manufacturing method. FIG. 13(a) is a schematic perspective view showing the entire laminated core, and FIG. 13(b) is a schematic cross-sectional view of a plane passing through the straight line DD illustrated in FIG. 13(a) and parallel to the central axis (common axis) of the common insertion hole. The laminated core 30 illustrated in FIG. 13(a) is composed of three layers of second cores 20. In each second core 20, a second electromagnetic steel sheet 22 having an octagonal second insertion hole 22a similar to the first electromagnetic steel sheet 13 illustrated in FIG. 12(a) and a first protrusion 22p protruding from a side at the periphery of the second insertion hole 22a toward the inside of the second insertion hole 22a is laminated on one end surface of the first core 10 formed by laminating the first electromagnetic steel sheets 13.

[0069] FIG. 14 is a schematic diagram illustrating the configuration of a laminated core formed from the laminated core illustrated in FIG. 13 by performing a bending process included in the third manufacturing method. FIG. 14(a) is a schematic perspective view illustrating the entire laminated core, and FIG. 14(b) is a schematic cross-sectional view of a plane passing through a straight line EE illustrated in FIG. 14(a) and parallel to the central axis (common axis) of the common insertion hole. The laminated core 30 illustrated in FIG. 14(a) is composed of three layers of second cores 20. In each second core 20, as illustrated in FIG. 14(b), the first protruding portion 22p illustrated in FIG. 13 is bent in the direction of the common axis to become a first bent portion 22b, which is in close contact with a portion corresponding to a side of the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet 13 (i.e., the inner circumferential surface of the insertion hole of the first core 10), thereby binding and fixing the multiple first electromagnetic steel sheets 13.

[0070] However, as described above, when the bending process is completed, the entire first bent portion may be in close contact with the inner peripheral surface of the insertion hole of the first core, or a part of the first bent portions may be in close contact with the inner peripheral surface of the insertion hole of the first core, or the first bent portions may not be in close contact with the inner peripheral surface of the insertion hole of the first core at all. Although not shown, as described above, adjacent second cores 20 are not bound and fixed to each other by the first bent portion 22b. Therefore, adjacent second cores 20 may be bound and fixed to each other by means of, for example, crimping.

[0071] In the above description, the shapes of the first and second insertion holes and the cross-sectional shape of the shaft are polygonal. However, as described above, the third method can also be applied to fitting a laminated core having a star-shaped polygonal insertion hole to a shaft having a polygonal or star-shaped polygonal cross section. Figure 15 is a schematic plan view illustrating the configuration of a first electromagnetic steel sheet having a star-shaped polygonal insertion hole used in the third manufacturing method, and the shapes of the first insertion holes 13Sa to 16Sa of the first electromagnetic steel sheets 13S to 16S illustrated in (a) to (d) are star-shaped octagonal, star-shaped heptagonal, star-shaped hexagonal, and star-shaped pentagonal, respectively.

[0072] FIG. 16 is a schematic perspective view illustrating the configuration of a laminated core having a common insertion hole of a star-shaped polygon formed by performing a bending process included in the third manufacturing method, and a shaft having a cross section of the corresponding star-shaped polygon. As illustrated in FIG. 16(a), the laminated core 30 has an insertion hole of an approximately star-shaped regular octagon, and as illustrated in FIG. 16(b), the shaft 40 has a cross section of an approximately star-shaped regular octagon. The "approximate star-shaped regular octagon" here means a shape in which the corners of the eight vertices of a star-shaped regular octagon and the eight valleys between the adjacent vertices are rounded. In this specification, even if a figure is partially modified from a "star-shaped polygon" in the strict sense, it is included in the "star-shaped polygon" as long as it can be recognized as a "star-shaped polygon" as a whole.

[0073] Fig. 17 is a schematic plan view illustrating the configuration of the first electromagnetic steel sheet 13S and the second electromagnetic steel sheet 24 having a substantially star-shaped regular octagonal through hole constituting the laminated core 30 illustrated in Fig. 16(a). As illustrated in Fig. 17(a), the first electromagnetic steel sheet 13S has the above-mentioned substantially star-shaped regular octagonal first through hole 13Sa. On the other hand, as illustrated in Fig. 17(b), the second electromagnetic steel sheet 24 has a substantially star-shaped regular octagonal second through hole 24a corresponding to the above-mentioned first through hole 13Sa and a plurality of (16 in Fig. 17) second protrusions 24p spaced apart from each other and protruding inward from the periphery of the second through hole 24a.

[0074] Then, a bending process is performed on the laminated core 30 constituted by the first electromagnetic steel sheet 13S and the second electromagnetic steel sheet 24 illustrated in Fig. 17, thereby obtaining the laminated core 30 illustrated in Fig. 16(a). Fig. 18(a) is a schematic cross-sectional view of the laminated core 30 taken along a plane passing through the straight line FF illustrated in Fig. 16(a) and parallel to the central axis (common axis) of the common insertion hole, and Fig. 18(b) is a schematic arrow view of the laminated core 30 observed from the direction of the arrow G shown in Fig. 17(a).

[0075] As illustrated in Fig. 17 and Fig. 18, a plurality of first protrusions 24p are bent in the direction of a common axis, which is the central axis of the common through-hole of the laminated core 30, to form a plurality of first bent portions 24b, and the first bent portions 24b are in close contact with the portions corresponding to the sides of the first through-hole 13Sa of a substantially star-shaped regular octagon. Thereafter, for example, as described later in the description of another embodiment of the present invention, the shaft 40 illustrated in Fig. 16(b) is pressed into the common through-hole of the laminated core 30. Fig. 18(c) is a schematic enlarged view showing a state in which the shaft 40 is pressed into the common through-hole of the laminated core 30 and the first bent portions 24b are sandwiched between the laminated core and the shaft. The portion illustrated in Fig. 18(c) corresponds to the portion H surrounded by a thick dashed line in Fig. 17(a). 18(c), the shaft 40 is sandwiched by a plurality of first inner circumferential surfaces, which are surfaces of the plurality of first bent portions 24b facing the common insertion hole. That is, the first bent portions 24b are interposed between the inner circumferential surface of the first insertion hole 13Sa and the outer circumferential surface of the shaft 40, and the inner circumferential surface of the first insertion hole 13Sa is not in contact with the outer circumferential surface of the shaft 40. In this manner, the third manufacturing method can also be applied to the manufacture of a laminated core having a star-shaped insertion hole that is to be fitted with a shaft having a star-shaped polygonal cross section.

[0076] 18(a), the first protrusions 24p are bent toward the central axis (common axis) of the common through hole to form the first bent portions 24b, and the entire first bent portions 24b are in close contact with the inner peripheral surface of the first through hole 13Sa. However, as described above, at least at the time when the bending process is completed, the first bent portions 24b formed by bending the first protrusions 24p may have regions that are not in close contact with the inner peripheral surface of the first through hole 13Sa, or the first bent portions 24b may not be in close contact with the inner peripheral surface of the first through hole 13Sa at all.

[0077] <effect> As described above, the shape of the common insertion hole of the laminated core manufactured by the third manufacturing method is a polygon or star-shaped polygon, and the first protrusion protrudes inward from a side at the periphery of the second insertion hole. Therefore, in the bending process, the first protrusion is bent along the direction of the common axis that is the central axis of the common insertion hole, and the first bent portion is formed so as to face a portion corresponding to a side of the inner circumferential surface of the first insertion hole (i.e., the inner circumferential surface of the insertion hole of the first core). As a result, in the fitting structure between the laminated core and the shaft manufactured by the third manufacturing method, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced, and therefore higher torque transmission performance can be achieved.

[0078] Fourth Embodiment Hereinafter, a method for producing a laminated core according to a fourth embodiment of the present invention (hereinafter, may be referred to as a "fourth production method") will be described with reference to the drawings.

[0079] According to the first to third manufacturing methods described above, the bent portion that holds the shaft in the fitting structure between the laminated core and the shaft has higher dimensional accuracy than the burring portion in the conventional technology described above. Therefore, according to the first to third manufacturing methods, it is possible to improve the centering accuracy and ensure the fitting strength to achieve reliable torque transmission. However, depending on the application of a rotating electric machine or the like that has a fitting structure between a laminated core and a shaft manufactured by any of the first to third manufacturing methods, a higher torque transmission performance may be required.

[0080] <composition> Therefore, the fourth manufacturing method is any one of the first to third manufacturing methods described above, and is a method for manufacturing a laminated core, in which a recess is formed in a portion of the inner surface of the first insertion hole that faces the first bent portion.

[0081] FIG. 19 is a schematic perspective view illustrating a configuration of a laminated core 30 formed by laminating a first electromagnetic steel sheet 12 (i.e., a first electromagnetic steel sheet 12 having a recess 12c formed in a portion facing the first bent portion 21b on the inner peripheral surface of a first insertion hole 12a) and a second electromagnetic steel sheet 21 used in the fourth manufacturing method. FIG. 19(a) is a schematic perspective view showing the entire laminated core 30, and FIG. 19(b) is a schematic enlarged view of a portion surrounded by a thick dashed line in FIG. 19(a). Note that in FIG. 19, in order to facilitate understanding of this embodiment, the second electromagnetic steel sheet 21 to be laminated at the top to form the second core 20 is omitted, and a state in which the recess 13c is exposed on the inner peripheral surface of the uppermost first core 10 is depicted.

[0082] As illustrated in FIG. 19, a plurality of first electromagnetic steel sheets 12 are laminated such that the recesses 12c formed in the individual first electromagnetic steel sheets 12 overlap each other in a projection view in the direction of the common axis. As a result, a groove-shaped depression extending in the direction of the common axis is formed by the recesses 12c of the plurality of first electromagnetic steel sheets 12 on the inner peripheral surface of the insertion hole of the first core 10 as a whole. Note that in FIG. 19, only one recess 12c is drawn on the inner peripheral surface of the first insertion hole 12a of the first electromagnetic steel sheet 12. However, as described above, the recess is formed in a portion facing the first bent portion 21b on the inner peripheral surface of the first insertion hole 12a, so in reality, a plurality of recesses 12c separated from each other are formed in a portion facing the first bent portion 21b on the inner peripheral surface of the first insertion hole 12a, similarly to the plurality of first bent portions 21b separated from each other.

[0083] Next, Fig. 20 is a schematic diagram showing a state in which the first bent portion 21b is partially immersed in the recess 12c in a fitting structure between a laminated core and a shaft manufactured by the fourth manufacturing method. Fig. 20(a) is a schematic cross-sectional view of a plane perpendicular to the common axis of the first electromagnetic steel sheet 12 in which the first bent portion 21b is partially immersed in the recess 12c, and Fig. 20(b) is a schematic enlarged view of a portion surrounded by a thick dashed line in Fig. 20(a). As illustrated in Fig. 20, in the fitting structure between a laminated core and a shaft manufactured by the fourth manufacturing method, the first bent portion 21b can be at least partially immersed in the recess 12c.

[0084] In addition, "at least partially embedded" here means that the entire first bent portion 21b in the thickness direction is not embedded in the recess 12c, but rather that a part of the first bent portion 21b in the thickness direction is embedded in the recess 12c and the other part is not embedded in the recess 12c. This makes it possible to more reliably reduce slippage between the laminated core and the shaft in the rotational direction, thereby achieving higher torque transmission performance.

[0085] In addition, a specific method for at least partially immersing the first bent portion 21b in the recess 12c formed on the inner peripheral surface of the laminated core manufactured by the fourth manufacturing method is not particularly limited. For example, the first bent portion 21b may be immersed in the recess 12c in the process of forming the first bent portions 21b by bending the first protruding portions 21p in the direction of the common axis in the above-mentioned bending process and at least partially contacting the inner peripheral surface of the first insertion hole 12a. Alternatively, the first bent portion 21b may be immersed in the recess 12c in the process of pressing the shaft into the common insertion hole of the laminated core in the press-fitting process described later in the description of the fitting method of the laminated core and the shaft according to another embodiment of the present invention. Furthermore, the first bent portion 21b may be immersed in the recess 12c in the process of performing the punching process on the first inner peripheral surfaces by inserting a punch into the common insertion hole of the laminated core in the striking process described later in the description of the fitting method of the laminated core and the shaft according to another embodiment of the present invention.

[0086] <effect> As described above, in the laminated core manufactured by the fourth manufacturing method, a recess is formed in a portion of the inner circumferential surface of the first insertion hole that faces the first bent portion. Therefore, in the fitting structure between the laminated core and the shaft manufactured by the fourth manufacturing method, the first bent portion can be at least partially immersed in the recess formed in the inner circumferential surface of the insertion hole of the first core. This makes it possible to more reliably reduce slippage between the laminated core and the shaft in the rotational direction, thereby achieving higher torque transmission performance.

[0087] Fifth Embodiment Hereinafter, a method for producing a laminated core according to a fifth embodiment of the present invention (hereinafter, may be referred to as a "fifth production method") will be described with reference to the drawings.

[0088] As described above, according to the first to fourth manufacturing methods, adhesion when the shaft is pressed into the insertion hole formed in the laminated core and rupture of the insulating coating of the electromagnetic steel sheets that accompany the crimping process between the electromagnetic steel sheets that make up the laminated core can be reduced, thereby reducing eddy current loss, and the fitting strength and centering accuracy between the laminated core and the shaft can be improved.

[0089] Furthermore, as described in the explanation of the third manufacturing method above, the cross-sectional shape of the common insertion hole of the laminated core and the cross-sectional shape of the shaft can be made into a polygon, such as an octagon or hexagon, or a star-shaped polygon, such as a star-shaped octagon or star-shaped hexagon, to reduce slippage between the laminated core and the shaft in the rotational direction.

[0090] Measures for reducing slippage in the rotational direction between the laminated core and the shaft are not limited to those described above. For example, by accommodating a protrusion acting as a key provided on either the laminated core or the shaft into a key groove provided on the other, slippage in the rotational direction between the laminated core and the shaft can be more reliably reduced.

[0091] <composition> Therefore, the fifth manufacturing method is a method for manufacturing a laminated core, which is any of the first to fourth manufacturing methods described above, in which a key groove, which is a recess extending in a direction parallel to the common axis, or a key, which is a protrusion extending in a direction parallel to the common axis, is provided on the inner surface of the common insertion hole.

[0092] Fig. 21 is a schematic plan view illustrating the configuration of a first electromagnetic steel sheet and a second electromagnetic steel sheet having polygonal insertion holes employed in the fifth manufacturing method. In the first electromagnetic steel sheet 19 illustrated in Fig. 21(a), the shape of the first insertion hole 19a is a substantially regular octagon, and one protrusion 19k is provided on each of the eight sides of the substantially regular octagon (eight in total). On the other hand, in the second electromagnetic steel sheet 25 illustrated in Fig. 21(b), the shape of the second insertion hole 25a is a substantially regular octagon like the shape of the first insertion hole 19a, and one protrusion 25k is provided on each of the eight sides of the substantially regular octagon (eight in total), and first protrusions 25p are provided on both sides of the protrusion 25k.

[0093] Next, Fig. 22(a) and (b) are respectively a schematic perspective view and a top view illustrating the configuration of a laminated core formed of the first electromagnetic steel sheet 19 and the second electromagnetic steel sheet 25 illustrated in Fig. 21. Fig. 23(a) is a schematic arrow view when the laminated core illustrated in Fig. 22(a) is observed from the direction of the arrow I shown in Fig. 22(b), and Fig. 23(b) is a schematic enlarged view of a portion where a shaft is pressed into a common through-hole of the laminated core illustrated in Fig. 22(a) and a key provided in the laminated core is accommodated in a key groove provided in the shaft. The portion illustrated in Fig. 23(b) corresponds to a portion J illustrated by a thick dashed line in Fig. 22(b).

[0094] As illustrated in (a) of FIG. 23, the laminated core 30 illustrated in FIG. 22 is constructed by laminating eight second cores 20. Each second core 20 is constructed by laminating a second electromagnetic steel sheet 25 on one end face of a first core 10 consisting of 15 first electromagnetic steel sheets 19, and bending a first protruding portion 25p to form a first bent portion 25b that extends along an inner peripheral surface of a first through hole of the first core 10. On the inner peripheral surface of the common through hole of the laminated core 30 thus constructed, a protruding portion 30k extending in a direction parallel to a common axis that is the central axis of the common through hole 30a is formed by laminating a protruding portion 19k provided on the first electromagnetic steel sheet 19 and a protruding portion 25k provided on the second electromagnetic steel sheet 25.

[0095] In the fifth manufacturing method, the laminated core 30 having the above-mentioned configuration is also formed by performing the first lamination step, the second lamination step, and the bending step. Then, for example, in a press-fitting step described later in the explanation of a method for fitting a laminated core and a shaft according to another embodiment of the present invention, the shaft can be press-fitted into the common insertion hole 30a of the laminated core 30. In such a press-fitting step, the shaft 40 is press-fitted into the common insertion hole 30a so that a key 30k formed on the inner peripheral surface of the common insertion hole 30a of the laminated core 30 is accommodated in a key groove 40g formed on the outer peripheral surface of the shaft 40, as illustrated in FIG. 23(b).

[0096] 21 to 23, the key 30k formed in the laminated core 30 is received in the key groove 40g formed in the shaft 40. Therefore, slippage between the laminated core 30 and the shaft 40 in the rotational direction can be more reliably reduced compared to a case where such a structure is not provided.

[0097] However, in the fifth manufacturing method, as described above, a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on the inner peripheral surface of the common insertion hole. That is, in the fifth manufacturing method, a key may be provided in the laminated core and a key groove may be provided in the shaft as shown in Figs. 21 to 23, or conversely, a key groove may be provided in the laminated core and a key may be provided in the shaft.

[0098] 23(b), the key 30k appears to be fitted into the key groove 40g. However, as long as the effect of more reliably reducing slippage between the laminated core and the shaft in the rotational direction is obtained, the key does not necessarily have to be fitted into the key groove, and it is sufficient that the key is accommodated in the key groove in the fitting structure between the laminated core and the shaft.

[0099] Furthermore, from the viewpoint of more reliably reducing slippage between the laminated core and the shaft in the rotational direction, it is preferable that the convex portions 19k and the convex portions 25k are formed on all of the first electromagnetic steel sheets 19 and the second electromagnetic steel sheets constituting the laminated core 30, as in the configurations exemplified in Fig. 21 to Fig. 23. However, as long as the effect of more reliably reducing slippage between the laminated core and the shaft in the rotational direction is obtained, for example, a configuration in which convex portions are formed only on the first electromagnetic steel sheets and not on the second electromagnetic steel sheets may also be adopted. Also, a configuration in which convex portions are not formed on some of the first electromagnetic steel sheets and / or some of the second electromagnetic steel sheets constituting the laminated core may also be adopted.

[0100] 21 to 23, eight keys 30k are formed around the entire inner circumferential surface of the common insertion hole 30a of the laminated core 30, and, although not all are shown, eight key grooves 40g are formed at corresponding positions on the outer circumferential surface of the shaft 40. However, the arrangement of the keys and key grooves is not limited to the above, and the keys and key grooves may be formed only in partial regions of the inner circumferential surface of the common insertion hole of the laminated core and the outer circumferential surface of the shaft.

[0101] In the configurations illustrated in Figs. 21 to 23, the shape of the common through hole 30a is a substantially regular octagon. However, the shape of the common through hole and the cross-sectional shape of the shaft of the laminated core to which the fifth manufacturing method is applied are not particularly limited, and may be circular or noncircular, as described above. Specific examples of noncircular cross sections include not only rotationally symmetric shapes such as ellipses, polygons such as octagons and hexagons, and star-shaped polygons such as star-shaped octagons and star-shaped hexagons, but also shapes that are not rotationally symmetric. Furthermore, shapes in which a part of a circle is missing are also included in the noncircular shape. In this way, the fifth method can be applied to the manufacture of laminated cores having a wide variety of shapes of common through holes.

[0102] <effect> As described above, in the fifth manufacturing method, a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on the inner peripheral surface of the common insertion hole. Therefore, for example, in a press-fitting step described later in the description of a method for fitting a laminated core and a shaft according to another embodiment of the present invention, a shaft having a key or a key groove formed on its outer peripheral surface corresponding to the key groove or key provided on the inner peripheral surface of the common insertion hole as described above can be press-fitted into the common insertion hole of the laminated core to accommodate the key in the key groove. As a result, according to the fifth manufacturing method, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced.

[0103] Sixth Embodiment Hereinafter, a method for producing a laminated core according to a sixth embodiment of the present invention (hereinafter, may be referred to as a "sixth production method") will be described with reference to the drawings.

[0104] As described above, according to the first to fifth manufacturing methods, in the fitting structure between a laminated core and a shaft manufactured by any of the first to fifth manufacturing methods, the first bent portion that clamps the shaft has higher dimensional accuracy than the burring portion in the conventional technology described above, thereby improving centering accuracy and ensuring fitting strength, thereby achieving reliable torque transmission.

[0105] Incidentally, it is known that in rotating electrical machines such as generators and electric motors, adverse effects such as deterioration or destruction of insulation, burning, deterioration of bearings, and deterioration of lubricants such as grease may occur due to heat generation during operation. For this reason, a technique is known in the art for cooling the shaft and laminated core, for example, by supplying cooling oil from one end of the shaft and allowing the cooling oil to flow through the inside of the shaft and into an oil passage provided inside the laminated core. Such a configuration can also be applied to the combination of the laminated core and shaft manufactured by the manufacturing method of the present invention.

[0106] <composition> Therefore, the sixth manufacturing method is any one of the first to fifth manufacturing methods described above, and is a method for manufacturing a laminated core, in which a first flow path for flowing a refrigerant is formed inside the laminated core, and a first opening communicating with the first flow path is provided on the inner surface of the common insertion hole.

[0107] Fig. 24 is a schematic diagram showing one example of the configuration of a laminated core formed by performing a bending process included in the sixth manufacturing method. Fig. 25 is a schematic plan view showing one example of the configuration of two types of first electromagnetic steel sheets constituting the laminated core illustrated in Fig. 24. Fig. 24(a) is a schematic perspective view of a laminated core 30, and Fig. 24(b) is a schematic cross-sectional view of the laminated core 30 taken along a plane passing through a straight line KK illustrated in Fig. 24(a) and parallel to the central axis (common axis) of the common insertion hole. The hollow arrow illustrated in Fig. 24(b) indicates one example of the flow of a refrigerant from a second flow passage formed inside a shaft (not shown).

[0108] Also, (a) of Fig. 25 is a schematic cross-sectional view of the laminated core 30 taken along a plane passing through the straight line LL in (b) of Fig. 24 and perpendicular to the central axis (common axis) of the common through-hole, and is also a plan view of the first electromagnetic steel sheet 13D constituting the relevant portion. Furthermore, (b) of Fig. 25 is a schematic cross-sectional view of the laminated core 30 taken along a plane passing through the straight line MM in (b) of Fig. 24 and perpendicular to the central axis (common axis) of the common through-hole, and is also a plan view of the first electromagnetic steel sheet 13A constituting the relevant portion. In addition, (c) of Fig. 24 is a schematic arrow view of the laminated core 30 as viewed from the direction of the arrow N shown in (a) of Fig. 25.

[0109] 24 and 25, a first flow passage 61 for flowing a refrigerant is formed inside the laminated core 30, and a first opening 62 communicating with the first flow passage 61 is provided on the inner circumferential surface of a common insertion hole of the laminated core 30. As illustrated in (a) and (b) of FIG. 25, the first electromagnetic steel sheets 13D and 13A are provided with through holes 61a that constitute the first flow passage 61 in the laminated core 30 formed by laminating these electromagnetic steel sheets and a second electromagnetic steel sheet (not shown). As illustrated in (b) of FIG. 25, the first electromagnetic steel sheet 13A is provided with a notch 62c that constitutes the first opening 62 communicating with the first flow passage 61 in the laminated core 30. Although not shown in Figure 25, the second electromagnetic steel sheet 22D constituting the laminated core 30 illustrated in Figure 24 has a configuration similar to the first electromagnetic steel sheet 13D illustrated in Figure 25 (a), except that it has a first protrusion.

[0110] By subjecting the first electromagnetic steel sheets 13D and 13A and the second electromagnetic steel sheet 22D having the above-mentioned configuration to the first lamination step, the second lamination step, and the folding step described above, a laminated core 30 can be obtained in which a first flow passage 61 for flowing a refrigerant is formed therein and a first opening 62 communicating with the first flow passage 61 is provided on the inner circumferential surface of a common insertion hole, as illustrated in Fig. 24. In the example shown in Fig. 24, the first opening 62 formed by laminating the notch 62c provided in the first electromagnetic steel sheet 13A overlaps with the first bent portion 22Db of the second electromagnetic steel sheet 22D, so that the portion of the first bent portion 22Db overlapping with the first opening 62 is removed in order to communicate the second flow passage formed inside the shaft (not shown) with the first flow passage 61. However, instead of the portion of the first bent portion 22Db that overlaps with the first opening 62, the entire first bent portion 22Db that overlaps with the first opening 62 may be removed. Naturally, when the first opening 62 is provided at a position that does not overlap with the first bent portion 22Db, there is no need to remove the first bent portion 22Db.

[0111] Incidentally, the first electromagnetic steel sheet 13A illustrated in FIG. 25(b) has two notches 62c on each side of the first insertion hole 13Aa of a substantially regular octagon, and as a result, two first openings 62 are formed on each side of the common insertion hole of a substantially regular octagon in the laminated core 30 illustrated in FIG. 24. On the radial outside of each of the notches 62c of the first electromagnetic steel sheet 13A, one through hole 61b is provided, which becomes a part of the first flow path 61 in the laminated core 30. Therefore, in the laminated core 30, on the radial outside of each of the first openings 62, one space is formed by stacking the through holes 61b. On the other hand, the through hole 61a provided in the first electromagnetic steel sheet 13D illustrated in FIG. 25(a) is provided at a position communicating with two adjacent through holes 61b of the first electromagnetic steel sheet 13A. Therefore, in the laminated core 30 , two first openings 62 formed on each side of the generally regular octagonal common insertion hole communicate with one first flow passage 61 .

[0112] However, in the laminated core 30 manufactured by the sixth manufacturing method, it is not necessarily necessary for the multiple first openings 62 to be connected to the first flow path 61 as described above, and each first opening 62 may be connected only to an individual first flow path 61.

[0113] FIG. 26 is a schematic diagram showing another example of the configuration of the laminated core formed by performing the bending process included in the sixth manufacturing method. FIG. 27 is a schematic plan view showing one example of the configuration of two types of first electromagnetic steel sheets constituting the laminated core illustrated in FIG. 26. FIG. 26(a) is a schematic perspective view of the laminated core 30, and FIG. 26(b) is a schematic cross-sectional view of the laminated core 30 taken along a plane passing through the straight line OO in FIG. 26(a) and parallel to the central axis (common axis) of the common through hole. FIG. 27(a) is a schematic cross-sectional view of the laminated core 30 taken along a plane passing through the straight line PP in FIG. 26(b) and perpendicular to the central axis (common axis) of the common through hole, and is also a plan view of the first electromagnetic steel sheet 13D constituting the relevant portion. Furthermore, (b) of Fig. 27 is a schematic cross-sectional view of the laminated core 30 taken along a plane passing through the straight line QQ depicted in (b) of Fig. 26 and perpendicular to the central axis (common axis) of the common insertion hole, and is also a plan view of the first electromagnetic steel sheet 13A constituting the relevant portion. In addition, (c) of Fig. 26 is a schematic arrow view of the laminated core 30 as observed from the direction of the arrow R shown in (a) of Fig. 27.

[0114] 26 and 27 has a similar configuration to the laminated core 30 illustrated in Figures 24 and 25, except that each of the first openings 62 communicates only with an individual first flow path 61S. In this manner, in the sixth manufacturing method, desired refrigerant flow paths can be provided by appropriately setting the through holes and / or cutouts in the first and second electromagnetic steel sheets.

[0115] In the fitting structure between the laminated core manufactured by the sixth manufacturing method and a shaft having a second flow passage formed therein and a second opening on the outer circumferential surface communicating with the second flow passage, the first flow passage formed inside the laminated core and the second flow passage formed inside the shaft can be made to communicate with each other by pressing the shaft into the common insertion hole so that the first opening formed on the inner circumferential surface of the common insertion hole of the laminated core faces the second opening formed on the outer circumferential surface of the shaft (not shown). As a result, the shaft and the laminated core can be effectively cooled by flowing the coolant inside the laminated core via the inside of the shaft. The fluid used as the coolant is not particularly limited as long as it can withstand the usage environment in applications such as a rotating electric machine having a fitting structure between the laminated core and the shaft fitted by the sixth manufacturing method and can effectively cool the shaft and the laminated core. Typically, oil is used as the coolant.

[0116] The sixth manufacturing method as described above can be implemented in combination with the second to fifth manufacturing methods described above. For example, FIG. 28 is a schematic diagram illustrating the configuration of a laminated core formed by performing a bending process included in the sixth manufacturing method applied to the second manufacturing method described with reference to FIG. 9 to FIG. 11. (a) and (b) of FIG. 28 are drawings corresponding to (b) and (c) of FIG. 24 and (b) and (c) of FIG. 26. Specifically, (a) of FIG. 28 is a schematic cross-sectional view of the laminated core 30 taken along a plane passing through the first flow passage 61 and the first opening 62 and parallel to the central axis (common axis) of the common through hole. (b) of FIG. 28 is a schematic front view of one side of the inner peripheral surface of the approximately regular octagonal common through hole of the laminated core 30 as viewed from the axis (common axis) side of the common through hole, similar to (c) of FIG. 24 and (c) of FIG. 26.

[0117] The first electromagnetic steel sheet constituting the laminated core 30 illustrated in Fig. 28 has a similar configuration to the first electromagnetic steel sheet 13D illustrated in Fig. 25 or Fig. 27. On the other hand, the second electromagnetic steel sheet constituting the laminated core 30 illustrated in Fig. 28 has a similar configuration to the second electromagnetic steel sheet 22D illustrated in Fig. 24 or Fig. 26, except that it is a second electromagnetic steel sheet in which a bent portion F2 or F3 is formed in the first protruding portion before becoming the first bent portion as illustrated in Fig. 10 referred to in the explanation of the second manufacturing method. In Fig. 28(a), the reference symbols of the bent portions formed in each of the first bent portions 22Db are indicated. Further, the second core 20 in which the first opening 62 is formed is composed of a first electromagnetic steel sheet 13D as illustrated in Figure 25 or Figure 27 (b) and a second electromagnetic steel sheet 22D in which no bent portion is formed as illustrated in Figure 24 or Figure 26, and the portion of the first bending portion 22Db that overlaps with the first opening 62 is removed.

[0118] In the laminated core 30 illustrated in FIG. 28, the shaft and the laminated core can be effectively cooled by flowing a coolant through the first flow passage 61 formed inside the laminated core 30 and the second flow passage formed inside the shaft (not shown). In addition, in the laminated core 30 illustrated in FIG. 28, due to the presence of a bent portion in the first protrusion, a portion separated from the inner circumferential surface of the insertion hole of the first core is formed in the first bent portion. Therefore, for example, when a shaft (not shown) is pressed into the common insertion hole of the laminated core 30 in a press-in process described later in the description of the fitting method of the laminated core and the shaft according to another embodiment of the present invention, the portion is pressed toward the inner circumferential surface of the insertion hole of the first core by the shaft, and the restoring force of the portion acts in a direction to clamp the shaft. As a result, the shaft pressed into the common insertion hole of the laminated core is more firmly clamped by the first inner circumferential surfaces of the multiple first bent portions. That is, the effect of the second manufacturing method, that is, a higher fitting strength is ensured and a higher torque transmission performance is achieved, can also be achieved.

[0119] <effect> As described above, in the sixth manufacturing method, the first flow passage for the coolant is formed inside the laminated core, and the first opening communicating with the first flow passage is provided on the inner circumferential surface of the common through hole of the laminated core. Therefore, in a fitting structure between a shaft having a second flow passage for the coolant formed inside and a second opening communicating with the second flow passage provided on the outer circumferential surface and a laminated core manufactured by the sixth manufacturing method, the first flow passage formed inside the laminated core and the second flow passage formed inside the shaft can be made to communicate with each other by pressing the shaft into the common through hole so that the first opening formed on the inner circumferential surface of the common through hole of the laminated core and the second opening formed on the outer circumferential surface of the shaft (not shown) face each other. As a result, the shaft and the laminated core can be effectively cooled by flowing the coolant into the laminated core through the inside of the shaft. That is, according to the sixth manufacturing method, problems such as deterioration or destruction of insulation, burning, deterioration of bearings, and deterioration of lubricants such as grease, which occur due to heat generation accompanying the operation of a rotating electric machine such as a generator and an electric motor having a fitting body of a laminated core and a shaft, can be reduced.

[0120] Seventh Embodiment Hereinafter, a method for producing a laminated core according to a seventh embodiment of the present invention (hereinafter, may be referred to as a "seventh production method") will be described with reference to the drawings.

[0121] As described above, in the first to sixth manufacturing methods, when a laminated core is formed by stacking a plurality of second cores, adjacent second cores are not bound and fixed to each other by the first bent portion, and therefore may be bound and fixed to each other by means of, for example, crimping. As described above, even in such a case, compared with the laminated core according to the conventional technology, the number of places where crimping is performed can be significantly reduced, so that short circuits between the electromagnetic steel sheets can be reduced and eddy current loss during use as a core of a rotating electric machine or the like can be reduced. However, from the viewpoint of reliably reducing eddy current loss during use as a core of a rotating electric machine or the like, it is preferable to further reduce the number of places where crimping is performed to further reduce the possibility of short circuits between the electromagnetic steel sheets.

[0122] <composition> Therefore, the seventh manufacturing method is any one of the above-mentioned first to sixth manufacturing methods, in which the first lamination step, the second lamination step, and the folding step are each performed as listed below.

[0123] In the first stacking process, a third electromagnetic steel sheet having a third insertion hole and a plurality of spaced-apart second protrusions protruding inward from the periphery of the third insertion hole is sandwiched between the plurality of first electromagnetic steel sheets constituting the first core so that the first insertion hole and the third insertion hole are coaxially connected to each other.

[0124] In the second stacking process, a laminated core is formed by stacking multiple second cores, each of which is formed by stacking a second electromagnetic steel plate on at least one end face of the first core so that the first insertion hole, the second insertion hole, and the third insertion hole are coaxially connected to each other to form a common insertion hole.

[0125] In the bending process, the multiple first protrusions are bent along the direction of the common axis to form multiple first bent portions, and the multiple second protrusions are bent along the direction of the common axis to form multiple second bent portions.

[0126] Furthermore, in the seventh manufacturing method, the first bent portions and the second bent portions have different index angles around the common axis and do not overlap with each other. In addition, in the direction of the common axis, one of the first range in which the first bent portions extend and the second range in which the second bent portions extend at least partially overlaps with the other of the first and second bent portions. In other words, in the laminated core manufactured by the seventh manufacturing method, the second bent portions of the third electromagnetic steel sheet extend so as to face the inner circumferential surfaces of the adjacent second cores.

[0127] <effect> As described above, in the laminated core manufactured by the seventh manufacturing method, the second bent portion of the third electromagnetic steel sheet extends so as to face the inner circumferential surface of the adjacent second cores. Therefore, for example, as described later in the description of the fitting method of the laminated core and the shaft according to another embodiment of the present invention, the shaft can be pressed into the common insertion hole of the laminated core manufactured by the seventh manufacturing method, and the shaft can be sandwiched not only by the first bent portion but also by the second bent portion. As a result, the adjacent second cores in the direction of the common axis are bound and fixed by the second bent portion, so that the entire laminated core is bound and fixed as a whole. That is, according to the seventh manufacturing method, it is not necessary to bind and fix the adjacent second cores to each other by means of, for example, crimping, so that the number of places where crimping is performed can be further reduced, the possibility of short circuit between the electromagnetic steel sheets can be further reduced, and eddy current loss can be reliably reduced when used as a core for a rotating electric machine or the like.

[0128] The seventh production method as described above can be carried out in combination with any of the second to sixth production methods described above. Each of such combinations will be described in detail below.

[0129] <Application of the 7th manufacturing method to the 2nd manufacturing method> When the seventh manufacturing method is applied to the above-mentioned second manufacturing method, one or more of the above-mentioned bent portions are provided in at least a portion of both or either of the first protrusion portion provided on the second electromagnetic steel sheet and the second protrusion portion provided on the third electromagnetic steel sheet.

[0130] That is, in the seventh manufacturing method applied to the second manufacturing method, prior to the folding step, in a partial bending step, one or more first bends are provided on at least a portion of the multiple first protrusions, the first bends being located at points bent in the same direction or the opposite direction to the direction in which the multiple first protrusions are bent in the folding step to form multiple first bends, and / or one or more second bends are provided on at least a portion of the multiple second protrusions, the second bends being located at points bent in the same direction or the opposite direction to the direction in which the multiple second protrusions are bent in the folding step to form multiple second bends.

[0131] Incidentally, the configuration of the first bent portion and / or the second bent portion provided on at least a portion of the plurality of first protrusions and / or the plurality of second protrusions as described above is similar to the configuration described in the explanation of the second manufacturing method with reference to Figures 9 to 11, and therefore will not be described here.

[0132] With the above configuration, in the laminated core formed of a third electromagnetic steel sheet in addition to the first and second electromagnetic steel sheets in the seventh manufacturing method, as in the above-described second manufacturing method, the first bent portion and / or the second bent portion can be formed at least in part of the first bent portion and / or the second bent portion at least in part of the first protrusions and / or the second protrusions, which is spaced apart from the inner circumferential surface of the common through hole of the laminated core at the time when the bending step is completed, as a result of the provision of the first bent portion and / or the second bent portion in at least in part of the first protrusions and / or the second protrusions. As a result, the shaft can be more firmly clamped by the restoring force of the above portion pressed against the inner circumferential surface when the shaft is press-fitted into the common through hole of the laminated core in the press-fitting step included in the fitting method of the laminated core and the shaft according to another embodiment of the present invention, so that a higher fitting strength can be ensured and a higher torque transmission performance can be achieved.

[0133] <Application of the 7th manufacturing method to the 3rd manufacturing method> When the seventh manufacturing method is applied to the third manufacturing method described above, the shape of the common insertion hole is a polygon or a star-shaped polygon, and therefore the shapes of the first insertion hole of the first electromagnetic steel sheet, the second insertion hole of the second electromagnetic steel sheet, and the third insertion hole of the third electromagnetic steel sheet, which constitute the common insertion hole, are also polygonal or star-shaped polygon.

[0134] Furthermore, the first protrusion protrudes inward from a side at the periphery of the second insertion hole, and the second protrusion protrudes inward from a side at the periphery of the third insertion hole. In addition, in the bending process, the first protrusion is bent along the direction of the common axis, which is the central axis of the common insertion hole, to form a first bent portion so as to face the portion corresponding to the side of the inner peripheral surface of the first insertion hole and the third insertion hole. Similarly, the second protrusion is bent along the direction of the common axis, which is the central axis of the common insertion hole, to form a second bent portion so as to face the portion corresponding to the side of the inner peripheral surface of the first insertion hole and the second insertion hole.

[0135] FIG. 29 is a schematic diagram illustrating the state of the laminated core at the time of completing the bending step included in the seventh manufacturing method applied to the third manufacturing method. FIG. 29(a) is a schematic perspective view showing the entire laminated core, and FIG. 29(b) is a schematic enlarged view of the part surrounded by the thick dashed line in FIG. 29(a). As illustrated in FIG. 29, a plurality of first inner circumferential surfaces, which are the inner circumferential surfaces of the first bent portion 22b of the second electromagnetic steel sheet 22, and a plurality of second inner circumferential surfaces, which are the inner circumferential surfaces of the second bent portion 51b of the third electromagnetic steel sheet 51, face the common insertion hole of the laminated core 30. Therefore, for example, by pressing the shaft into the common insertion hole in the press-fitting step included in the method of fitting the laminated core and the shaft according to another embodiment of the present invention, the shaft can be sandwiched between the plurality of first inner circumferential surfaces and the plurality of second inner circumferential surfaces.

[0136] As shown in Fig. 29, the first bent portions 22b and the second bent portions 51b have different index angles around a common axis and do not overlap with each other. In the example shown in Fig. 29, the first bent portions 22b and the second bent portions 51b are adjacent to each other along the inner peripheral surface of the common insertion hole, but they do not necessarily need to be in contact with each other and may be spaced apart from each other.

[0137] Fig. 30 is a schematic cross-sectional view illustrating the lamination state of the first electromagnetic steel sheet, the second electromagnetic steel sheet, and the third electromagnetic steel sheet in the laminated core illustrated in Fig. 29. Fig. 30(a) is a schematic cross-sectional view taken along a plane passing through the straight line SS illustrated in Fig. 29(b) and parallel to the central axis (common axis) of the common insertion hole. That is, Fig. 30(a) is a cross-sectional view taken along a plane passing through the first bent portion 22b. In Fig. 30(a), the cross section of the third electromagnetic steel sheet 51 without the second bent portion 51b is shown as a filled-in rectangle. 30(a), a plurality of first protrusions (22p; no reference numeral is shown in the figure) are bent in the direction of a common axis in a bending step included in the seventh manufacturing method to form a plurality of first bent portions 22b, and the first bent portions 22b are at least partially in close contact with the inner circumferential surface of a first insertion hole in the first electromagnetic steel sheet 13 and the inner circumferential surface of a third insertion hole in the third electromagnetic steel sheet 51. As a result, the first electromagnetic steel sheet 13 and the third electromagnetic steel sheet 51, to which the plurality of first bent portions 22b are in close contact, are bound and fixed to each other to form the second core 20.

[0138] On the other hand, FIG. 30(b) is a schematic cross-sectional view taken along a plane passing through the straight line TT depicted in FIG. 29(b) and parallel to the central axis (common axis) of the common through-hole. That is, FIG. 30(b) is a cross-sectional view taken along a plane passing through the second bent portion 51b. In FIG. 30(b), a cross-section of the second electromagnetic steel sheet 22 without the first bent portion 22b is shown as a black rectangle. In the example shown in FIG. 30(b), a plurality of second protrusions (51p. No reference numeral is shown in the figure) are bent toward the common axis in the bending step included in the seventh manufacturing method to form a plurality of second bent portions 51b, and the second bent portions 51b are at least partially in close contact with the inner circumferential surface of the first through-hole of the first electromagnetic steel sheet 13 and the inner circumferential surface of the second through-hole of the second electromagnetic steel sheet 22. As a result, the first electromagnetic steel sheet 13 and the second electromagnetic steel sheet 22, in which the plurality of second bent portions 51b are in close contact with each other, are bound and fixed to each other.

[0139] As illustrated in (b) of FIG. 30, the second bent portion 51b of the third electromagnetic steel sheet 51 is at least partially in close contact with the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet 13 and the inner circumferential surface of the second insertion hole of the second electromagnetic steel sheet 22, straddling the second electromagnetic steel sheet 22. Therefore, the second bent portion 51b binds and fixes the second cores 20 adjacent in the direction of the common axis. On the other hand, as illustrated in (a) of FIG. 30, the first bent portion 22b of the second electromagnetic steel sheet 22 is at least partially in close contact with the inner circumferential surface of the first insertion hole of the first electromagnetic steel sheet 13 and the inner circumferential surface of the third insertion hole of the third electromagnetic steel sheet 51, straddling the third electromagnetic steel sheet 51. That is, as illustrated in (b) of Figure 29, in the direction of the common axis, one of the first range in which the first bent portion 22b extends and the second range in which the second bent portion 51b extends at least partially overlaps with the other of the multiple ranges.

[0140] Although the laminated core 30 illustrated in FIG. 29 has a common insertion hole that is approximately a regular octagon, the shape of the laminated core formed by the seventh manufacturing method applied to the third manufacturing method is not limited to an approximately regular octagon, and may be, for example, various polygonal or star-shaped polygonal shapes such as those illustrated in FIGS. 12 to 18 referred to in the explanation of the third manufacturing method.

[0141] With the above configuration, in the seventh manufacturing method, in the laminated core formed of a third electromagnetic steel sheet in addition to the first and second electromagnetic steel sheets, the shape of the common insertion hole can be polygonal or star-shaped, as in the third manufacturing method described above. Therefore, by press-fitting a shaft having a corresponding polygonal or star-shaped cross section into the laminated core, slippage in the rotational direction between the laminated core and the shaft can be reduced, thereby achieving higher torque transmission performance.

[0142] 30(a), the first protrusions 22p are bent in the direction of the common axis, which is the central axis of the common insertion hole, to form the first bent portions 22b, and the entire first bent portions 22b are in close contact with the inner circumferential surfaces of the first insertion hole and the third insertion hole. However, as described above, it is sufficient that at least a partial area of ​​the first bent portions 22b is in close contact with the inner circumferential surfaces of the first insertion hole and / or the third insertion hole when the shaft is press-fitted into the common insertion hole. That is, at the time when the bending process is completed, as in the laminated core 30 illustrated in (a) of Figure 30, the entirety of the multiple first bending portions 22b may be in close contact with the inner surfaces of the first insertion hole and the third insertion hole, or only a portion of the multiple first bending portions 22b may be in close contact with the inner surfaces of the first insertion hole and / or the third insertion hole, or the multiple first bending portions 22b may not be in close contact at all with the inner surfaces of the first insertion hole and the third insertion hole.

[0143] 30(b), the second protrusions 51p are bent in the direction of the common axis, which is the central axis of the common insertion hole, to form the second bent portions 51b, and the entire second bent portions 51b are in close contact with the inner circumferential surfaces of the first insertion hole and the second insertion hole. However, as in the above, it is sufficient that at least a partial area of ​​the second bent portions 51b is in close contact with the inner circumferential surfaces of the first insertion hole and / or the second insertion hole when the shaft is press-fitted into the common insertion hole. That is, at the time when the bending process is completed, as in the laminated core 30 illustrated in (b) of Figure 30, the entirety of the multiple second bending portions 51b may be in close contact with the inner surfaces of the first insertion hole and the second insertion hole, or only a portion of the multiple second bending portions 51b may be in close contact with the inner surfaces of the first insertion hole and / or the second insertion hole, or the multiple second bending portions 51b may not be in close contact at all with the inner surfaces of the first insertion hole and the second insertion hole.

[0144] <Application of the 7th manufacturing method to the 4th manufacturing method> As described above, in the seventh manufacturing method, not only the first electromagnetic steel sheet and the second electromagnetic steel sheet but also the third electromagnetic steel sheet constitute a laminated core. Meanwhile, in the fourth manufacturing method described above, a recess is formed in a portion of the inner circumferential surface of the first insertion hole facing the first bent portion. Therefore, when the seventh manufacturing method is applied to the fourth manufacturing method described above, recesses are formed in a portion of the inner circumferential surface of the first insertion hole and the third insertion hole facing the first bent portion and / or a portion of the inner circumferential surface of the first insertion hole and the second insertion hole facing the second bent portion.

[0145] With the above configuration, in the laminated core formed by the third electromagnetic steel sheet in addition to the first and second electromagnetic steel sheets by the seventh manufacturing method, the first bent portion and / or the second bent portion can be at least partially immersed in the recess formed on the inner circumferential surface of the common insertion hole of the laminated core, as in the above-mentioned fourth manufacturing method. As a result, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced, thereby achieving higher torque transmission performance.

[0146] Incidentally, the state in which the first bent portion and / or the second bent portion of the second electromagnetic steel sheet and / or the third electromagnetic steel sheet, respectively, are immersed in the recesses formed in the other electromagnetic steel sheets as described above is similar to the state described in the explanation of the fourth manufacturing method with reference to Figures 19 and 20, and therefore will not be explained here.

[0147] <Application of the 7th manufacturing method to the 5th manufacturing method> As described above, in the seventh manufacturing method, not only the first electromagnetic steel sheet and the second electromagnetic steel sheet but also the third electromagnetic steel sheet constitute a laminated core. Meanwhile, in the above-mentioned fifth manufacturing method, a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on the inner peripheral surface of the common insertion hole. Therefore, in the seventh manufacturing method applied to the fifth manufacturing method, a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on the inner peripheral surface of the common insertion hole of the laminated core formed by laminating the first electromagnetic steel sheet, the second electromagnetic steel sheet, and the third electromagnetic steel sheet.

[0148] Therefore, for example, in the press-fitting step described later in the explanation of the method of fitting a laminated core and a shaft according to another embodiment of the present invention, a shaft having a key or key groove formed on its outer peripheral surface corresponding to the key groove or key provided on the inner peripheral surface of the common insertion hole as described above can be press-fitted into the common insertion hole of the laminated core to accommodate the key in the key groove. As a result, according to the fifth manufacturing method to which the seventh manufacturing method is applied, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced.

[0149] As described above, the configuration of the key groove provided on one of the inner surface of the common insertion hole of the laminated core and the outer surface of the shaft, and the key provided on the other, as well as the structure in which the key is accommodated in the key groove when the laminated core and the shaft are fitted together, are similar to the configuration described in the explanation of the fifth manufacturing method with reference to Figures 21 to 23, and therefore will not be described here.

[0150] <Application of the 7th manufacturing method to the 6th manufacturing method> As described above, in the seventh manufacturing method, not only the first and second electromagnetic steel sheets but also the third electromagnetic steel sheet constitute the laminated core. Meanwhile, in the sixth manufacturing method described above, a first flow passage for flowing a coolant is formed inside the laminated core, and a first opening communicating with the first flow passage is provided on the inner circumferential surface of the common through hole of the laminated core.

[0151] Therefore, in order to apply the seventh manufacturing method to the sixth manufacturing method described above, it is necessary to provide a first flow path for flowing a coolant and a first opening communicating with the first flow path in a laminated core made of three types of electromagnetic steel sheets including not only the first electromagnetic steel sheet and the second electromagnetic steel sheet but also the third electromagnetic steel sheet. For this reason, in the sixth manufacturing method to which the seventh manufacturing method is applied, it is necessary to drill a through hole constituting the first flow path formed inside the laminated core in the same manner as in the second electromagnetic steel sheet used in the sixth manufacturing method. Also, in the case where the second bent portion of the third electromagnetic steel sheet overlaps with the first opening, it is necessary to remove the part of the second bent portion overlapping with the first opening or the entire second bent portion overlapping with the first opening, in the same manner as in the second electromagnetic steel sheet used in the sixth manufacturing method.

[0152] The configurations of the first flow passages and the first openings formed in the laminated core are similar to those described in the explanation of the sixth manufacturing method with reference to Figures 24 to 28. Here, the configuration of the laminated core formed when the seventh manufacturing method, in which a third electromagnetic steel sheet is used in addition to the first and second electromagnetic steel sheets, is applied to the sixth manufacturing method, will be described in detail below with reference to Figures 31 to 33.

[0153] Fig. 31 is a schematic perspective view illustrating the configuration of a laminated core formed by the sixth manufacturing method to which the seventh manufacturing method is applied. However, Fig. 31(a) is a schematic perspective view of a laminated core formed by the sixth manufacturing method to which the seventh method is not applied (i.e., the laminated core does not include the third electromagnetic steel sheet) for comparison. Fig. 31(e) is a schematic top view of the laminated core, which is also illustrated for the purpose of showing the arrow direction in Figs. 32 and 33, which are arrow views. Figs. 32(a) and (b) and Figs. 33(a) and (b) are schematic arrow views of the laminated cores illustrated in Figs. 31(a) and (b) and Figs. 31(c) and (d), respectively, when observed from the direction of the arrow U shown in Fig. 31(e).

[0154] FIG. 31(a) is a schematic perspective view of a laminated core formed by the sixth manufacturing method to which the seventh manufacturing method is not applied, as described above, for comparison, and has a similar configuration to the laminated core 30 illustrated in FIG. 24(a). FIG. 32(a) is a U-arrow view of the laminated core 30 illustrated in FIG. 31(a), as described above, and has a similar configuration to the laminated core 30 illustrated in FIG. 24(c). That is, a first flow passage for flowing a refrigerant is formed inside the laminated core 30, and a first opening 62 communicating with the first flow passage is provided on the inner circumferential surface of the common insertion hole of the laminated core 30, although not shown. In addition, since the first opening 62 overlaps with the first bent portion 22Db of the second electromagnetic steel sheet 22D, a portion of the first bent portion 22Db overlapping with the first opening 62 is removed in order to communicate a second flow passage formed inside a shaft, not shown, with the first flow passage, not shown.

[0155] Next, Fig. 31(b) is a schematic perspective view of a laminated core formed by the sixth manufacturing method to which the seventh manufacturing method is applied (i.e., the laminated core includes a third electromagnetic steel sheet), and Fig. 32(b) is a view of the laminated core 30 illustrated in Fig. 31(b) as viewed from the arrow U. In the example illustrated in Fig. 31(b) and Fig. 32(b), a row of first bent portions 22Db and a row of second bent portions 51Db are adjacent to each side of a common through hole having a substantially regular octagonal shape and are connected in the direction of a common axis. In addition, although not illustrated, a first flow path for flowing a refrigerant is formed inside the laminated core 30, and a first opening 62 communicating with the first flow path is provided on the inner peripheral surface of the common through hole of the laminated core 30. Furthermore, since the first opening 62 overlaps with the first bending portion 22Db and the second bending portion 51Db, the portions of the first bending portion 22Db and the second bending portion 51Db that overlap with the first opening 62 are removed in order to connect the second flow path formed inside the shaft (not shown) to the first flow path (not shown).

[0156] Next, FIG. 31(c) is also a schematic perspective view of a laminated core formed by the sixth manufacturing method to which the seventh manufacturing method is applied (i.e., the laminated core includes a third electromagnetic steel sheet), and FIG. 33(a) is a view of the laminated core 30 illustrated in FIG. 31(c). In the example illustrated in FIG. 31(c) and FIG. 33(a), a row of first bent portions 22Db and two rows of second bent portions 51Db arranged to sandwich the first bent portions 22Db from both sides in the circumferential direction are adjacent to each other on each side of a common through hole having a substantially regular octagonal shape, and are connected in the direction of a common axis. In addition, although not illustrated, a first flow path for flowing a refrigerant is formed inside the laminated core 30, and a first opening 62 communicating with the first flow path is provided on the inner peripheral surface of the common through hole of the laminated core 30. Furthermore, since the first opening 62 overlaps with the first bending portion 22Db, the portion of the first bending portion 22Db that overlaps with the first opening 62 is removed in order to connect the second flow path formed inside the shaft (not shown) to the first flow path (not shown).

[0157] The laminated core 30 illustrated in Figures 31(d) and 33(b) has a similar configuration to the laminated core 30 illustrated in Figures 31(c) and 33(a) described above, except that instead of the portion that overlaps with the first opening 62 of the first bending portion 22Db, the entire first bending portion 22Db that overlaps with the first opening 62 (the portion surrounded by a thick dashed line in Figure 33(b)) has been removed.

[0158] As described above, in the seventh manufacturing method, in the laminated core formed of the third electromagnetic steel sheet in addition to the first and second electromagnetic steel sheets, the first flow path for the coolant is formed inside the laminated core, and the first opening communicating with the first flow path is provided on the inner circumferential surface of the common through hole of the laminated core, as in the sixth manufacturing method described above. Therefore, in the fitting structure between the shaft in which the second flow path for the coolant is formed inside and the second opening communicating with the second flow path is provided on the outer circumferential surface, and the laminated core manufactured by the sixth manufacturing method to which the seventh manufacturing method is applied, the first flow path formed inside the laminated core and the second flow path formed inside the shaft can be communicated by pressing the shaft into the common through hole so that the first opening formed on the inner circumferential surface of the common through hole of the laminated core and the second opening formed on the outer circumferential surface of the shaft face each other. As a result, the shaft and the laminated core can be effectively cooled by flowing the coolant inside the laminated core via the inside of the shaft. In other words, the sixth manufacturing method to which the seventh manufacturing method is applied can also reduce problems such as deterioration or destruction of insulation, burning, deterioration of bearings, and deterioration of lubricants such as grease, which are caused by heat generation accompanying the operation of rotating electric machines such as generators and electric motors that have a mating body of a laminated core and a shaft.

[0159] Eighth Embodiment As mentioned at the beginning of this specification, the present invention relates not only to a method for producing a laminated core, but also to a laminated core.

[0160] Hereinafter, a laminated core according to an eighth embodiment of the present invention (hereinafter, may be referred to as a "first laminated core") will be described.

[0161] <composition> The first laminated core is a laminated core formed by laminating a plurality of electromagnetic steel sheets having insertion holes, and is composed of a plurality of second cores laminated so that the common insertion holes of one second core or adjacent second cores are coaxially connected to each other. The second core is formed by laminating a second electromagnetic steel sheet having a second insertion hole on at least one end surface of a first core formed by laminating a plurality of first electromagnetic steel sheets having a first insertion hole so that the first insertion holes are coaxially connected to each other. In the second core, the first insertion hole and the second insertion hole are coaxially connected to each other to form a common insertion hole that is one insertion hole. Furthermore, the second electromagnetic steel sheet has a plurality of first bent portions that are bent at the periphery of the second insertion hole and extend in the direction of a common axis that is the central axis of the common insertion hole.

[0162] The first laminated core having the above-mentioned configuration can be manufactured, for example, by the manufacturing method (first manufacturing method) of the laminated core according to the first embodiment of the present invention described above. Note that the configuration of the first laminated core has already been described in detail with reference to Figures 2 to 8, so a description thereof will be omitted here.

[0163] <effect> As is clear from the above-mentioned description of the effects achieved by the first manufacturing method, in the first laminated core, as described later in the description of other embodiments of the present invention, when a shaft is pressed into the common insertion hole of the laminated core manufactured by the first manufacturing method, the shaft is sandwiched by the multiple first inner circumferential surfaces that are the surfaces facing the common insertion hole of the multiple first bent portions. Therefore, with the first laminated core, adhesion when the shaft is pressed into the insertion hole formed in the laminated core and breakage of the insulating coating of the electromagnetic steel sheets that accompanies crimping of the electromagnetic steel sheets that constitute the laminated core can be reduced, thereby reducing eddy current loss, and the fitting strength and centering accuracy between the laminated core and the shaft can be improved.

[0164] Ninth Embodiment A laminated core according to a ninth embodiment of the present invention (hereinafter, may be referred to as a "second laminated core") will be described below.

[0165] <composition> The second laminated core is the above-mentioned first laminated core, which is a laminated core in which one or more first bend portions, which are points bent in the same direction or the opposite direction to the direction in which the multiple first bend portions are bent around the periphery of the second insertion hole, are provided in at least a portion of the multiple first bend portions.

[0166] The second laminated core having the above-mentioned configuration can be manufactured, for example, by the manufacturing method (second manufacturing method) of the laminated core according to the second embodiment of the present invention described above. Note that the configuration of the second laminated core has already been described in detail with reference to Figures 10 and 11, so a description thereof will be omitted here.

[0167] <effect> As is clear from the above-mentioned description of the effect achieved by the second manufacturing method, in the second laminated core, the portion separated from the inner peripheral surface of the insertion hole of the first core is formed in the first bent portion. Therefore, for example, when a shaft is pressed into the common insertion hole as described later in the description of another embodiment of the present invention, the shaft presses the portion toward the inner peripheral surface of the insertion hole of the first core, and the restoring force of the portion acts in a direction to clamp the shaft. As a result, the shaft pressed into the common insertion hole of the laminated core is more firmly clamped by the first inner peripheral surfaces of the multiple first bent portions. In other words, according to the second manufacturing method, a higher fitting strength can be ensured and a higher torque transmission performance can be achieved.

[0168] Tenth Embodiment A laminated core according to a tenth embodiment of the present invention (hereinafter, may be referred to as a "third laminated core") will be described below.

[0169] <composition> The third laminated core is the first laminated core or the second laminated core described above, and is a laminated core in which the shape of the common insertion hole is a polygon or a star-shaped polygon, and the first bent portion extends from a side at the periphery of the second insertion hole.

[0170] The third laminated core having the above-mentioned configuration can be manufactured, for example, by the manufacturing method of the laminated core according to the third embodiment of the present invention (third manufacturing method). Note that the configuration of the third laminated core has already been described in detail with reference to Figures 12 to 18, so a description thereof will be omitted here.

[0171] <effect> As is clear from the above description of the effects achieved by the third manufacturing method, in the third laminated core, the shape of the common insertion hole is a polygon or star-shaped polygon, and the first bent portion extends from a side at the periphery of the second insertion hole along the direction of the common axis, which is the central axis of the common insertion hole. That is, the first bent portion is formed so as to face a portion corresponding to a side of the inner circumferential surface of the first insertion hole (i.e., the inner circumferential surface of the insertion hole of the first core). As a result, in the fitting structure between the third laminated core and the shaft, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced, thereby achieving higher torque transmission performance.

[0172] Eleventh Embodiment Hereinafter, a laminated core according to an eleventh embodiment of the present invention (hereinafter, may be referred to as a "fourth laminated core") will be described.

[0173] <composition> The fourth laminated core is any one of the first to third laminated cores described above, and is a laminated core in which a recess is formed in a portion facing the first bent portion on the inner surface of the first insertion hole.

[0174] The fourth laminated core having the above-mentioned configuration can be manufactured, for example, by the manufacturing method of the laminated core according to the fourth embodiment of the present invention (fourth manufacturing method). Note that the configuration of the fourth laminated core has already been described in detail with reference to Figures 19 and 20, so a description thereof will be omitted here.

[0175] <effect> As is clear from the above description of the effects achieved by the fourth manufacturing method, in the fourth laminated core, a recess is formed in a portion of the inner circumferential surface of the first insertion hole that faces the first bent portion. Therefore, in the fitting structure between the fourth laminated core and the shaft, the first bent portion can be at least partially immersed in the recess formed in the inner circumferential surface of the insertion hole of the first core. This makes it possible to more reliably reduce slippage between the laminated core and the shaft in the rotational direction, thereby achieving higher torque transmission performance.

[0176] Twelfth Embodiment A laminated core according to a twelfth embodiment of the present invention (hereinafter, may be referred to as a "fifth laminated core") will be described below.

[0177] <composition> The fifth laminated core is any one of the first to fourth laminated cores described above, and is a laminated core in which a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on the inner surface of the common insertion hole.

[0178] The fifth laminated core having the above-mentioned configuration can be manufactured, for example, by the manufacturing method of the laminated core according to the fifth embodiment of the present invention (fifth manufacturing method). Note that the configuration of the fifth laminated core has already been described in detail with reference to Figs. 21 to 23, so a description thereof will be omitted here.

[0179] <effect> As is clear from the above description of the effects achieved by the fifth manufacturing method, in the fifth laminated core, a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on the inner peripheral surface of the common insertion hole. Therefore, for example, in the press-fitting step described later in the description of the fitting method of the laminated core and the shaft according to another embodiment of the present invention, a shaft having a key or a key groove formed on its outer peripheral surface corresponding to the key groove or key provided on the inner peripheral surface of the common insertion hole as described above can be press-fitted into the common insertion hole of the laminated core to accommodate the key in the key groove. As a result, the fifth laminated core can more reliably reduce slippage between the laminated core and the shaft in the rotational direction.

[0180] Thirteenth Embodiment A laminated core according to a thirteenth embodiment of the present invention (hereinafter, may be referred to as a "sixth laminated core") will be described below.

[0181] <composition> The sixth laminated core is any one of the first to fifth laminated cores described above, and is a laminated core in which a first flow path for flowing a refrigerant is formed inside the laminated core, and a first opening communicating with the first flow path is provided on the inner surface of the common insertion hole.

[0182] The sixth laminated core having the above-mentioned configuration can be manufactured, for example, by the manufacturing method of the laminated core according to the sixth embodiment of the present invention (sixth manufacturing method). Note that the configuration of the sixth laminated core has already been described in detail with reference to Figures 24 to 28, so a description thereof will be omitted here.

[0183] <effect> As is clear from the above description of the effects achieved by the sixth manufacturing method, in the sixth laminated core, a first flow passage for the coolant is formed inside the laminated core, and a first opening communicating with the first flow passage is provided on the inner circumferential surface of the common through hole of the laminated core. Therefore, in a fitting structure between the sixth laminated core and a shaft having a second flow passage for the coolant formed inside and a second opening communicating with the second flow passage provided on the outer circumferential surface, the first flow passage formed inside the laminated core and the second flow passage formed inside the shaft can be communicated by pressing the shaft into the common through hole so that the first opening formed on the inner circumferential surface of the common through hole of the laminated core faces the second opening formed on the outer circumferential surface of the shaft (not shown). As a result, the shaft and the laminated core can be effectively cooled by flowing the coolant inside the laminated core via the inside of the shaft. In other words, the sixth laminated core can reduce problems such as deterioration or destruction of insulation, burning, deterioration of bearings, and deterioration of lubricants such as grease, which are caused by heat generation during operation of rotating electric machines such as generators and electric motors that have a fitted laminated core and a shaft.

[0184] Fourteenth Embodiment A laminated core according to a fourteenth embodiment of the present invention (hereinafter, may be referred to as a "seventh laminated core") will be described below.

[0185] <composition> The seventh laminated core is any one of the first to fifth laminated cores described above. In the seventh laminated core, a third electromagnetic steel sheet having a third through hole is sandwiched between the first electromagnetic steel sheets constituting the first core so that the first through hole and the third through hole are coaxially connected to each other. In addition, a laminated core is formed by stacking a plurality of second cores each formed by stacking a second electromagnetic steel sheet on at least one end face of the first core so that the first through hole, the second through hole, and the third through hole are coaxially connected to each other to form a common through hole. Furthermore, the third electromagnetic steel sheet has a plurality of second bent portions that are bent around the periphery of the third through hole and extend in the direction of the common axis. In addition, the plurality of first bent portions and the plurality of second bent portions have different index angles around the common axis and do not overlap each other. In addition, in the direction of the common axis, one of the first range, which is a range in which the first bent portion extends, and the second range, which is a range in which the second bent portion extends, at least partially overlaps with the other of the multiple ranges.

[0186] The seventh laminated core having the above-mentioned configuration can be manufactured, for example, by the manufacturing method of the laminated core according to the seventh embodiment of the present invention (seventh manufacturing method). Note that the configuration of the seventh laminated core has already been described in detail in the description of the seventh manufacturing method, so a description thereof will be omitted here.

[0187] <effect> As described above, in the seventh laminated core, the second bent portion of the third electromagnetic steel sheet extends so as to face the inner circumferential surfaces of the adjacent second cores. Therefore, for example, as described later in the description of the method of fitting a laminated core and a shaft according to another embodiment of the present invention, the shaft can be pressed into the common insertion hole of the seventh laminated core and the shaft can be clamped not only by the first bent portion but also by the second bent portion. As a result, the second cores adjacent in the direction of the common axis are bound and fixed by the second bent portion, so that the entire laminated core is bound and fixed as a whole. That is, according to the seventh laminated core, it is not necessary to bind and fix the adjacent second cores to each other by means of, for example, crimping, so that the number of places where crimping is performed can be further reduced, the possibility of short circuit between the electromagnetic steel sheets can be further reduced, and eddy current loss can be reliably reduced when used as a core for a rotating electric machine or the like.

[0188] The seventh laminated core structure described above can be combined with any of the second to sixth laminated core structures described above. Each of these combinations will be described in detail below.

[0189] <Application of the 7th laminated core to the 2nd laminated core> When the configuration of the seventh laminated core is applied to the configuration of the second laminated core described above, one or more of the above-mentioned bent portions are provided in at least a portion of both or either of the first protruding portion provided on the second electromagnetic steel sheet and the second protruding portion provided on the third electromagnetic steel sheet.

[0190] That is, in the seventh laminated core applied to the second laminated core, one or more first bends are provided on at least a portion of the plurality of first bends, the first bends being located at the periphery of the second insertion hole in the same direction or the opposite direction to the direction in which the plurality of first bends are bent, and / or one or more second bends are provided on at least a portion of the plurality of second bends, the second bends being located at the periphery of the third insertion hole in the same direction or the opposite direction to the direction in which the plurality of second bends are bent.

[0191] In addition, the configuration of the first bending portion and / or the second bending portion provided in at least a portion of the multiple first bending portions and / or multiple second bending portions as described above is similar to the configuration described in the explanation of the second manufacturing method with reference to Figures 9 to 11, so the explanation here is omitted.

[0192] With the above configuration, in the seventh laminated core constituted by the third electromagnetic steel sheet in addition to the first and second electromagnetic steel sheets, as in the second laminated core described above, the first bent portions and / or the second bent portions are provided at least in part of the plurality of first bent portions and / or the plurality of second bent portions, so that at least in part of the first bent portions and / or the second bent portions has a portion spaced from the inner circumferential surface of the common through hole of the laminated core at the time when the bending step is completed. As a result, the shaft can be more firmly clamped by the restoring force of the portion pressed against the inner circumferential surface when the shaft is press-fitted into the common through hole of the laminated core in the press-fitting step included in the method for fitting the laminated core and the shaft according to another embodiment of the present invention, so that a higher fitting strength can be ensured and a higher torque transmission performance can be achieved.

[0193] <Application of 7th laminated core to 3rd laminated core> When the seventh laminated core configuration is applied to the third laminated core configuration described above, the shape of the common insertion hole is a polygon or a star-shaped polygon. Therefore, the shapes of the first insertion hole of the first electromagnetic steel sheet, the second insertion hole of the second electromagnetic steel sheet, and the third insertion hole of the third electromagnetic steel sheet, which constitute the common insertion hole, are also polygonal or star-shaped polygon.

[0194] Furthermore, the first bent portion extends from a side at the periphery of the second insertion hole, and the second bent portion extends from a side at the periphery of the third insertion hole. In other words, the first bent portion is formed so as to face the portions corresponding to the sides of the inner peripheral surfaces of the first insertion hole and the third insertion hole. Similarly, the second bent portion is formed so as to face the portions corresponding to the sides of the inner peripheral surfaces of the first insertion hole and the second insertion hole.

[0195] The third laminated core to which the seventh laminated core having the above-mentioned configuration is applied can be manufactured, for example, by the third manufacturing method to which the seventh manufacturing method described above is applied. Note that, since the configuration of the third laminated core to which the seventh laminated core is applied has already been described in detail with reference to Figures 29 and 30 regarding the third manufacturing method to which the seventh manufacturing method described above is applied, a description thereof will be omitted here.

[0196] As is clear from the description of the effects achieved by the third manufacturing method to which the seventh manufacturing method is applied, in the third laminated core to which the seventh laminated core is applied, the shape of the common insertion hole can be polygonal or star-shaped polygonal like the third laminated core described above, even in a laminated core constituted by a third electromagnetic steel sheet in addition to the first and second electromagnetic steel sheets. Therefore, by press-fitting a shaft having a corresponding polygonal or star-shaped polygonal cross section into the laminated core, slippage between the laminated core and the shaft in the rotational direction can be reduced, thereby achieving higher torque transmission performance.

[0197] <Application of 7th laminated core to 4th laminated core> As described above, the seventh laminated core is composed of three types of electromagnetic steel sheets including not only the first electromagnetic steel sheet and the second electromagnetic steel sheet but also the third electromagnetic steel sheet. Meanwhile, in the fourth laminated core described above, a recess is formed in a portion of the inner circumferential surface of the first insertion hole facing the first bent portion. Therefore, in the configuration of the fourth laminated core to which the configuration of the seventh laminated core is applied, recesses are formed in a portion of the inner circumferential surface of the first insertion hole and the third insertion hole facing the first bent portion and / or a portion of the inner circumferential surface of the first insertion hole and the second insertion hole facing the second bent portion.

[0198] With the above configuration, in the laminated core formed by the seventh manufacturing method using the third electromagnetic steel sheet in addition to the first and second electromagnetic steel sheets, the first bent portion and / or the second bent portion can be at least partially recessed into the recess formed on the inner circumferential surface of the common insertion hole of the laminated core, as in the fourth laminated core described above. As a result, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced, thereby achieving higher torque transmission performance.

[0199] Incidentally, the state in which the first bent portion and / or the second bent portion of the second electromagnetic steel sheet and / or the third electromagnetic steel sheet, respectively, are immersed in the recesses formed in the other electromagnetic steel sheets as described above is similar to the state described in the explanation of the fourth manufacturing method with reference to Figures 19 and 20, and therefore will not be explained here.

[0200] <Application of 7th laminated core to 5th laminated core> As described above, the seventh laminated core is composed of three types of electromagnetic steel sheets including not only the first electromagnetic steel sheet and the second electromagnetic steel sheet but also the third electromagnetic steel sheet. Meanwhile, in the above-mentioned fifth laminated core, a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on the inner peripheral surface of the common insertion hole. Therefore, in the configuration of the fifth laminated core to which the configuration of the seventh laminated core is applied, a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on the inner peripheral surface of the common insertion hole of the laminated core formed by laminating the first electromagnetic steel sheet, the second electromagnetic steel sheet, and the third electromagnetic steel sheet.

[0201] Therefore, for example, in a press-fitting step described later in the description of a method for fitting a laminated core and a shaft according to another embodiment of the present invention, a shaft having a key or key groove formed on its outer peripheral surface corresponding to the key groove or key provided on the inner peripheral surface of the common insertion hole as described above can be press-fitted into the common insertion hole of the laminated core to accommodate the key in the key groove. As a result, the fifth laminated core to which the configuration of the seventh laminated core is applied can more reliably reduce slippage between the laminated core and the shaft in the rotational direction.

[0202] As described above, the configuration of the key groove provided on one of the inner surface of the common insertion hole of the laminated core and the outer surface of the shaft, and the key provided on the other, as well as the structure in which the key is accommodated in the key groove when the laminated core and the shaft are fitted together, are similar to the configuration described in the explanation of the fifth manufacturing method with reference to Figures 21 to 23, and therefore will not be described here.

[0203] <Application of 7th laminated core to 6th laminated core> As described above, the seventh laminated core is made of three types of electromagnetic steel sheets including not only the first and second electromagnetic steel sheets but also the third electromagnetic steel sheet. Meanwhile, in the sixth laminated core described above, a first flow passage for flowing a coolant is formed inside the laminated core, and a first opening communicating with the first flow passage is provided on the inner peripheral surface of the common through hole of the laminated core.

[0204] Therefore, in order to apply the configuration of the seventh laminated core to the configuration of the sixth laminated core described above, it is necessary to provide a first flow path for flowing the refrigerant and a first opening communicating with the first flow path in a laminated core made of three types of electromagnetic steel sheets including not only the first electromagnetic steel sheet and the second electromagnetic steel sheet but also the third electromagnetic steel sheet. For this reason, in a sixth laminated core to which the configuration of the seventh laminated core is applied, a through hole constituting the first flow path formed inside the laminated core needs to be drilled in the third electromagnetic steel sheet as well, similar to the second electromagnetic steel sheet constituting the sixth laminated core. Also, similar to the second electromagnetic steel sheet constituting the sixth laminated core, when the second bent portion of the third electromagnetic steel sheet overlaps with the first opening, it is necessary to remove the part of the second bent portion overlapping with the first opening or the entire second bent portion overlapping with the first opening.

[0205] The configuration of the first flow path and the first opening formed in the laminated core is similar to the configuration described in the explanation of the sixth manufacturing method with reference to Figures 24 to 28. Moreover, the configuration of the laminated core formed when the configuration of the seventh laminated core made of three types of electromagnetic steel sheets including not only the first electromagnetic steel sheet and the second electromagnetic steel sheet but also the third electromagnetic steel sheet is applied to the sixth laminated core is similar to the configuration described in the explanation of the sixth manufacturing method to which the seventh manufacturing method is applied with reference to Figures 31 to 33, and therefore will not be described here.

[0206] As described above, in the seventh laminated core made of three kinds of electromagnetic steel sheets including not only the first electromagnetic steel sheet and the second electromagnetic steel sheet but also the third electromagnetic steel sheet, the first flow passage for the coolant is formed inside the laminated core, and the first opening communicating with the first flow passage is provided on the inner circumferential surface of the common through hole of the laminated core, as in the sixth laminated core described above. Therefore, in the fitting structure between the sixth laminated core to which the configuration of the seventh laminated core is applied and the shaft in which the second flow passage for the coolant is formed inside and the second opening communicating with the second flow passage is provided on the outer circumferential surface, the first flow passage formed inside the laminated core and the second flow passage formed inside the shaft can be communicated by pressing the shaft into the common through hole so that the first opening formed on the inner circumferential surface of the common through hole of the laminated core and the second opening formed on the outer circumferential surface of the shaft face each other. As a result, the shaft and the laminated core can be effectively cooled by flowing the coolant inside the laminated core via the inside of the shaft. In other words, the sixth laminated core to which the configuration of the seventh laminated core is applied can also reduce problems such as deterioration or destruction of insulation, burning, deterioration of bearings, and deterioration of lubricants such as grease, which are caused by heat generation accompanying the operation of rotating electric machines such as generators and electric motors that have a fitting between a laminated core and a shaft.

[0207] Fifteenth Embodiment As described at the beginning of this specification, the present invention relates not only to a method for manufacturing a laminated core and a laminated core, but also to a method for fitting a laminated core to a shaft.

[0208] Hereinafter, a method for fitting a laminated core and a shaft according to a fifteenth embodiment of the present invention (hereinafter, may be referred to as a "first fitting method") will be described.

[0209] <composition> The first fitting method is a method of fitting a laminated core and a shaft by press-fitting the shaft into the common insertion hole of any of the laminated cores according to the eighth embodiment of the present invention (first laminated core) to the laminated cores according to the eleventh embodiment of the present invention (fourth laminated core). The first fitting method includes a press-fitting step of press-fitting the shaft into the common insertion hole and clamping the shaft between the multiple first inner circumferential surfaces, which are the surfaces of the multiple first bent portions that face the common insertion hole.

[0210] FIG. 34 is a flow chart illustrating the flow of each step in the case where the press-fitting step included in the first fitting method is performed following any one of the manufacturing method for a laminated core according to the first embodiment of the present invention (first manufacturing method) to the manufacturing method for a laminated core according to the fourth embodiment of the present invention (fourth manufacturing method). In step S10, step S20, and step S30 surrounded by thick dashed lines in FIG. 34, the first lamination step, the second lamination step, and the bending step included in any one of the first manufacturing method to the fourth manufacturing method are performed, respectively. However, when the second laminated core manufactured by the second manufacturing method described above is adopted, as described with reference to FIG. 9 in the description of the second manufacturing method described above, step S15 in which the partial bending step described above is performed is added before step S30 in which the bending step is performed. Note that the details of the first lamination step, the second lamination step, the bending step, and the partial bending step have already been described in detail in the description of the first manufacturing method to the fourth manufacturing method described above, and therefore will not be described here.

[0211] 34, the press-fitting step included in the first fitting method is performed following the first lamination step, the second lamination step, and the bending step included in any of the first to fourth manufacturing methods as described above, but the press-fitting step does not necessarily have to be performed following the first lamination step, the second lamination step, and the bending step. That is, the press-fitting step included in the first fitting method may be performed on any of the first to fourth laminated cores described above.

[0212] The press-in process performed in step S40 shown in Figure 34 is a process of pressing the shaft 40 into the common insertion hole with a predetermined press-in allowance Mp, as described with reference to Figures 6 and 7 in the explanation of the first manufacturing method, to clamp the shaft 40 between a plurality of first inner surfaces, which are the surfaces facing the common insertion hole of the plurality of first bending portions 21b.

[0213] Incidentally, the configurations of the first to fourth laminated cores and the configuration of the fitting structure between the laminated cores and the shaft achieved by the first fitting method have already been described in detail with reference to Figures 2 to 20 in the explanation of the manufacturing methods for the laminated cores according to the first to fourth embodiments of the present invention (i.e., the first to fourth manufacturing methods) and the laminated cores according to the eighth to eleventh embodiments of the present invention (i.e., the first to fourth laminated cores), so a detailed explanation will be omitted here.

[0214] <effect> As is clear from the explanation of the effects achieved by the first to fourth manufacturing methods and the first to fourth laminated cores described above, the first fitting method allows the shaft to be press-fitted into the common insertion hole of the laminated core and clamped by the first bent portion. As a result, adhesion when the shaft is press-fitted into the insertion hole of the laminated core and breakage of the insulating coating of the electromagnetic steel sheets caused by crimping the electromagnetic steel sheets that make up the laminated core are reduced, thereby reducing eddy current loss and improving the fitting strength and centering accuracy between the laminated core and the shaft.

[0215] Sixteenth Embodiment A fitting method for fitting a laminated core and a shaft according to a sixteenth embodiment of the present invention (hereinafter, may be referred to as a "second fitting method") will be described below.

[0216] As described above, in the first fitting method, the portion that clamps the shaft to be pressed into the common insertion hole in the pressing process is the first inner surface of the first bent portion formed by bending the first protrusion portion made of a steel plate that constitutes the second electromagnetic steel plate.

[0217] As described above, the first bent portion has higher dimensional accuracy in thickness, height, etc. than the burred portion in the conventional technology. As a result, the press-fit allowance (Mp) of the shaft into the common insertion hole can be guaranteed, and high centering accuracy and fitting strength can be achieved. Furthermore, compared to the burred portion in the conventional technology, the first bent portion has a uniform thickness and the first inner peripheral surface is smooth. Therefore, even though the first bent portion is not arranged all around but is arranged intermittently, the first inner peripheral surface and the shaft can be in surface contact with each other with a sufficient effective contact area. Therefore, reliable torque transmission can be achieved.

[0218] However, depending on the application, such as in a rotating electrical machine having a fitting structure between a laminated core and a shaft fitted by the fitting method of the present invention, higher torque transmission performance may be required.

[0219] <composition> Therefore, the second fitting method is the above-mentioned first fitting method, which is a method of fitting a laminated core and a shaft, further including a punching process of performing a punching process on the multiple first inner circumferential surfaces by inserting a punch into the common insertion hole before the pressing process.

[0220] FIG. 35 is a flow chart illustrating the flow of each step in the case where the stretching step and the press-fitting step included in the second fitting method are performed following any one of the manufacturing method for a laminated core according to the first embodiment of the present invention (first manufacturing method) to the manufacturing method for a laminated core according to the fourth embodiment of the present invention (fourth manufacturing method). In step S10, step S20, and step S30 surrounded by thick dashed lines in FIG. 35, the first lamination step, the second lamination step, and the bending step included in any one of the first manufacturing method to the fourth manufacturing method are performed, respectively. However, when the second laminated core manufactured by the second manufacturing method described above is adopted, as described with reference to FIG. 9 in the description of the second manufacturing method described above, step S15 in which a partial bending step is performed is added before step S30 in which the bending step is performed. Note that the details of the first lamination step, the second lamination step, the bending step, and the partial bending step have already been described in detail in the description of the first manufacturing method to the fourth manufacturing method described above, and therefore will not be described here.

[0221] 35, the first lamination step, the second lamination step, and the bending step included in any of the first to fourth manufacturing methods are followed by the squeezing step and the press-fitting step included in the second fitting method, but the squeezing step and the press-fitting step do not necessarily have to be performed following the first lamination step, the second lamination step, and the bending step. That is, the squeezing step and the press-fitting step included in the second fitting method may be performed on any of the first to fourth laminated cores described above.

[0222] The press-in process performed in step S40 shown in Figure 35 is, as described with reference to Figures 6 and 7 in the explanation of the first manufacturing method, a process of pressing the shaft 40 into the common insertion hole with a predetermined press-in allowance Mp, and clamping the shaft 40 between a plurality of first inner surfaces, which are the surfaces facing the common insertion hole of the multiple first bending portions 21b.

[0223] The configurations of the first to fourth laminated cores and the configuration of the fitting structure between the laminated core and the shaft achieved by the first fitting method have already been described in detail with reference to Figures 2 to 20 in the explanation of the manufacturing methods of the laminated core according to the first to fourth embodiments of the present invention (i.e., the first to fourth manufacturing methods) and the laminated core according to the eighth to eleventh embodiments of the present invention (i.e., the first to fourth laminated cores). Therefore, a description of these will be omitted and the change in the first inner circumferential surface accompanying the execution of the striking process will be described in detail below.

[0224] Fig. 36 is a schematic diagram illustrating a change in the first inner peripheral surface accompanying the execution of the rolling process included in the second fitting method. Fig. 36(a) is a schematic cross-sectional view of the laminated core at the time when the bending process is completed, and Fig. 36(b) is a schematic cross-sectional view of the laminated core at the time when the rolling process is completed. As illustrated in Fig. 36(a), the first bent portion 21b of the second electromagnetic steel sheet 21 before the rolling process is performed has a predetermined first sheet thickness T1. As described above, the first bent portion 21b has higher dimensional accuracy in sheet thickness, height, etc. than the burring portion in the conventional technology.

[0225] However, depending on the application of a rotating electric machine having a fitting structure between a laminated core and a shaft, there are cases where a very high torque transmission performance is required, and there is a concern that the first bent portion 21b, which provides an inner peripheral surface that holds the shaft pressed into the common insertion hole, does not necessarily have a sufficiently uniform thickness and smooth first inner peripheral surface to meet such requirements. Examples of causes of such concerns include uneven thickness and / or thickness variations of the sheet material itself from which the second electromagnetic steel sheet 21 is punched, deformation occurring when punching the second electromagnetic steel sheet 21, and / or deformation and / or thickness changes accompanying the execution of the bending process. The same is true for the first bent portion 22b described above.

[0226] Therefore, in the second fitting method, as described above, a punching process is performed before the press-fitting process, in which a punch is inserted into the common insertion hole of the laminated core to perform a pressing process on the first inner peripheral surfaces. As a result, as illustrated in FIG. 36(b), the thickness of the first bent portion 21b is slightly reduced (by ΔT) and becomes a more uniform predetermined second thickness T2 (T2=T1-ΔT). In addition, the first inner peripheral surfaces of the first bent portion 21b become smoother. That is, the dimensional accuracy of the first inner peripheral surfaces that define the space into which the shaft is pressed in the press-fitting process is further improved.

[0227] However, the effects brought about by the execution of the ironing process are not limited to the above-mentioned effects. For example, as shown in the part surrounded by the thick dashed circle in FIG. 36(a), when the bending process is completed, a small gap may be generated between the tip of the first bent portion 21b and the base end (bent portion) of the first bent portion 21b adjacent in the direction of the common axis. As described above, the execution of the ironing process reduces the plate thickness of the first bent portion 21b slightly, and the corresponding material (constituent material) plastically flows from the base end side to the tip end side and flows into the above-mentioned gap, so that the above-mentioned gap is reduced or disappears. Therefore, the effective contact area between the inner circumferential surface (first inner circumferential surface) of the first bent portion 21b and the shaft can be increased, and thus a higher torque transmission performance can be achieved.

[0228] <effect> As described above, in the second fitting method, a punching process is performed before the press-fitting process, in which a punch is inserted into the common insertion hole to perform a pressing process on the first inner peripheral surfaces. This makes it possible to make the plate thickness of the first bent portion more uniform and the first inner peripheral surfaces smoother. As a result, the dimensional accuracy of the first inner peripheral surfaces that define the space into which the shaft is pressed in the press-fitting process is further improved, and the press-fitting allowance (Mp) of the shaft into the common insertion hole can be more reliably guaranteed. In other words, according to the second fitting method, higher centering accuracy and fitting strength can be achieved in the fitting of the laminated core and the shaft, and therefore more reliable torque transmission can be achieved.

[0229] Seventeenth Embodiment A fitting method for fitting a laminated core and a shaft according to a seventeenth embodiment of the present invention (hereinafter, may be referred to as a "third fitting method") will be described below.

[0230] As described above, in the fourth laminated core, a recess is formed in a portion of the inner circumferential surface of the first insertion hole that faces the first bent portion. Therefore, in the fitting structure between the fourth laminated core and the shaft, the first bent portion can be at least partially recessed into the recess formed in the inner circumferential surface of the insertion hole of the first core. This makes it possible to more reliably reduce slippage between the laminated core and the shaft in the rotational direction, thereby achieving higher torque transmission performance.

[0231] As described above, the specific method for at least partially immersing the first bent portion in the recess is not particularly limited. For example, the first bent portion may be immersed in the recess during a process of forming a plurality of first bent portions by bending the plurality of first protruding portions in the direction of the common axis in a bending step included in the fourth manufacturing method. Alternatively, the first bent portion may be immersed in the recess during a process of pressing the shaft into the common insertion hole of the fourth laminated core in a pressing step included in the fourth laminated core fitting method.

[0232] <composition> Therefore, the third fitting method is a method of fitting a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of the laminated core (fourth laminated core) according to the eleventh embodiment of the present invention. The third fitting method includes a press-fitting step of press-fitting the shaft into the common insertion hole and sandwiching the shaft between the first inner peripheral surfaces of the first bent portions, which are the surfaces facing the common insertion hole. Furthermore, in the third fitting method, the first bent portions are at least partially immersed in the recesses in the press-fitting step.

[0233] The fourth laminated core can be manufactured, for example, by the manufacturing method of the laminated core according to the fourth embodiment of the present invention (fourth manufacturing method). The configuration of the fourth laminated core and the state in which the first bent portion is recessed have already been described in detail with reference to Figures 19 and 20 for the fourth manufacturing method, so description thereof will be omitted here.

[0234] <effect> As described above, in the third fitting method, the fourth laminated core is used as a laminated core having a common insertion hole into which the shaft is press-fitted, and the first bent portion is at least partially immersed in the recess in the press-fitting process. Therefore, according to the third fitting method, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced, thereby achieving higher torque transmission performance.

[0235] Eighteenth Embodiment Hereinafter, a fitting method between a laminated core and a shaft according to an eighteenth embodiment of the present invention (hereinafter, may be referred to as a "fourth fitting method") will be described.

[0236] As described above in the explanation of the second fitting method, depending on the application, such as in a rotating electric machine having a fitting structure between a laminated core and a shaft fitted by the fitting method of the present invention, higher torque transmission performance may be required.

[0237] <composition> Therefore, the fourth fitting method is a method of fitting a laminated core and a shaft, which is the third fitting method described above, and further includes a punching process of performing punching on the multiple first inner circumferential surfaces by inserting a punch into the common insertion hole before the pressing process.

[0238] As described above, the fourth fitting method has the same configuration as the third fitting method described above, except that the pressing step is performed before the press-fitting step. The configuration of the fourth laminated core has already been described in detail for the fourth manufacturing method with reference to Figures 19 and 20. The pressing step has already been described in detail for the second fitting method with reference to Figures 35 and 36. Therefore, a detailed description of the fourth fitting method will be omitted.

[0239] <effect> As described above, in the fourth fitting method, the fourth laminated core is used as a laminated core having a common through hole into which the shaft is press-fitted, and the pressing step is performed before the press-fitting step. Therefore, in the fourth fitting method, the plate thickness of the first bent portion can be made more uniform and the first inner peripheral surface can be made smoother. As a result, the dimensional accuracy of the first inner peripheral surfaces that define the space into which the shaft is press-fitted in the press-fitting step is further improved, and the press-fitting allowance (Mp) of the shaft into the common through hole can be more reliably guaranteed. In other words, according to the fourth fitting method, higher centering accuracy and fitting strength can be achieved in the fitting of the laminated core and the shaft, and therefore more reliable torque transmission can be achieved.

[0240] Nineteenth Embodiment Hereinafter, a fitting method of a laminated core and a shaft according to a nineteenth embodiment of the present invention (hereinafter, may be referred to as a "fifth fitting method") will be described.

[0241] As described above, in the fourth laminated core, a recess is formed in a portion of the inner circumferential surface of the first insertion hole that faces the first bent portion. Therefore, in the laminated core manufactured by the fourth manufacturing method or in the fitting structure between the fourth laminated core and the shaft, the first bent portion can be at least partially recessed into the recess formed in the inner circumferential surface of the insertion hole of the first core. This makes it possible to more reliably reduce slippage between the laminated core and the shaft in the rotational direction, thereby achieving higher torque transmission performance.

[0242] As described above, the specific method for at least partially immersing the first bent portion in the recess is not particularly limited. For example, the first bent portion may be immersed in the recess in a process of forming a plurality of first bent portions by bending a plurality of first protruding portions in the direction of the common axis in a bending process included in the fourth manufacturing method. Alternatively, the first bent portion may be immersed in the recess in a process of pressing the shaft into the common through hole of the fourth laminated core in a press-fitting process included in the fitting method of the fourth laminated core and the shaft. Furthermore, the first bent portion may be immersed in the recess in a process of performing a punching process on a plurality of first inner circumferential surfaces by inserting a punch into the common through hole of the fourth laminated core in a striking process included in the fourth fitting method using the fourth laminated core.

[0243] <composition> Therefore, the fifth fitting method is the above-mentioned fourth fitting method, which is a method of fitting the laminated core and the shaft, in which the first bent portion is at least partially immersed in the recess in the rolling step.

[0244] As described above, the fifth fitting method has the same configuration as the fourth fitting method described above, except that the first bent portion is at least partially inserted into the recess in the pressing step performed before the press-fitting step. The configuration of the fourth laminated core and the state in which the first bent portion is inserted into the recess have already been described in detail with reference to Figures 19 and 20 for the fourth manufacturing method described above. The pressing step has already been described in detail with reference to Figures 35 and 36 in the description of the second fitting method described above. Therefore, a detailed description of the fifth fitting method will be omitted.

[0245] <effect> As described above, in the fifth fitting method, the first bent portion is at least partially sunk into the recess in the squeezing step performed before the press-fitting step. Therefore, according to the fifth fitting method, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced, thereby achieving higher torque transmission performance.

[0246] Twentieth Embodiment A fitting method for fitting a laminated core and a shaft according to a twentieth embodiment of the present invention (hereinafter, may be referred to as a "sixth fitting method") will be described below.

[0247] In the above-mentioned first to sixth laminated cores, when a laminated core is formed by laminating a plurality of second cores, adjacent second cores are not bound and fixed to each other by the first bent portion, and therefore may be bound and fixed to each other by means of, for example, crimping. Even in such a case, the number of places where crimping is performed can be significantly reduced compared to the laminated core according to the conventional technology, so that short circuits between the electromagnetic steel sheets can be reduced and eddy current loss during use as a core for a rotating electric machine or the like can be reduced. However, from the viewpoint of reliably reducing eddy current loss during use as a core for a rotating electric machine or the like, it is preferable to further reduce the number of places where crimping is performed to further reduce the possibility of short circuits between the electromagnetic steel sheets.

[0248] <composition> Therefore, the sixth fitting method is a method for fitting a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of the laminated core (seventh laminated core) according to the above-mentioned fourteenth embodiment of the present invention. In the press-fitting step included in the sixth fitting method, the shaft is press-fitted into the common insertion hole, and the shaft is sandwiched between the first inner circumferential surfaces, which are surfaces facing the common insertion hole of the first bent portions, and the second inner circumferential surfaces, which are surfaces facing the common insertion hole of the second bent portions.

[0249] As described above, the sixth fitting method has the same configuration as the first fitting method described above, except that the seventh laminated core is used as a laminated core having a common insertion hole into which the shaft is press-fitted, and the shaft is press-fitted into the common insertion hole in the press-fitting step so that the shaft is sandwiched not only by the first inner circumferential surfaces but also by the second inner circumferential surfaces. The seventh laminated core can be manufactured, for example, by the seventh manufacturing method described above. The configuration of the seventh laminated core has already been described in detail in the description of the seventh manufacturing method described above. Therefore, a detailed description of the sixth fitting method will be omitted.

[0250] <effect> As described above, in the seventh laminated core, the second bent portion of the third electromagnetic steel sheet extends so as to face the inner circumferential surfaces of the adjacent second cores. Therefore, according to the sixth fitting method, the shaft can be pressed into the common through-hole of the seventh laminated core, and the shaft can be clamped not only by the first bent portion but also by the second bent portion. As a result, the adjacent second cores in the direction of the common axis are bound and fixed by the second bent portion, so that the entire laminated core is bound and fixed as a whole. That is, according to the sixth fitting method, it is not necessary to bind and fix the adjacent second cores to each other by means of, for example, crimping, so that the number of places where crimping is performed can be further reduced, the possibility of short-circuiting between the electromagnetic steel sheets can be further reduced, and eddy current loss can be reliably reduced when used as a core for a rotating electric machine or the like.

[0251] Twenty-first embodiment Hereinafter, a fitting method for fitting a laminated core and a shaft according to a twenty-first embodiment of the present invention (hereinafter, may be referred to as a "seventh fitting method") will be described.

[0252] As described above, in the sixth fitting method, the portion that clamps the shaft to be pressed into the common insertion hole in the pressing process is the first inner circumferential surface of the first bent portion formed by bending the first protrusion portion made of the steel plate that constitutes the second electromagnetic steel plate, and the second inner circumferential surface of the second bent portion formed by bending the second protrusion portion made of the steel plate that constitutes the third electromagnetic steel plate.

[0253] As described above, the first bent portion has higher dimensional accuracy in thickness, height, etc., compared to the burring portion in the conventional technology. As a result, the press-fitting allowance (Mp) of the shaft into the common insertion hole can be guaranteed, and high centering accuracy and fitting strength can be achieved. Furthermore, compared to the burring portion in the conventional technology, the thickness of the first bent portion is uniform and the first inner peripheral surface is smooth. Therefore, even though the first bent portion is not arranged all around but is arranged intermittently, the first inner peripheral surface and the shaft can be in surface contact with each other with a sufficient effective contact area. Therefore, reliable torque transmission can be achieved. The same applies to the second bent portion provided in the above-mentioned seventh laminated core.

[0254] However, depending on the application, such as in a rotating electrical machine having a fitting structure between a laminated core and a shaft fitted by the fitting method of the present invention, higher torque transmission performance may be required.

[0255] <composition> Therefore, the seventh fitting method is a method of fitting a laminated core and a shaft, which is the fifth fitting method described above, and further includes a punching process of performing punching on the multiple first inner circumferential surfaces and the multiple second inner circumferential surfaces by inserting a punch into the common insertion hole before the pressing process.

[0256] As described above, the seventh fitting method has the same configuration as the sixth fitting method described above, except that the seventh laminated core is used as a laminated core having a common through hole into which the shaft is pressed, and a punch is inserted into the common through hole in a pressing process performed before the pressing process, thereby performing a pressing process on not only the first inner peripheral surfaces but also the second inner peripheral surfaces. The seventh laminated core can be manufactured, for example, by the seventh manufacturing method. The configuration of the seventh laminated core has already been described in detail in the description of the seventh manufacturing method described above. Furthermore, the pressing process has already been described in detail in the description of the second fitting method described above, with reference to Figures 35 and 36. Therefore, a detailed description of the seventh fitting method will be omitted.

[0257] <effect> As described above, in the seventh laminated core, the first bent portion of the second electromagnetic steel sheet and the second bent portion of the third electromagnetic steel sheet extend to face the inner peripheral surface of the common insertion hole. In the punching process performed before the press-fitting process in the seventh fitting method, the first inner peripheral surfaces and the second inner peripheral surfaces are punched by inserting a punch into the common insertion hole. Therefore, the plate thickness of the first bent portion and the second bent portion can be made more uniform, and the first inner peripheral surface and the second inner peripheral surface can be made smoother. As a result, the dimensional accuracy of the first inner peripheral surfaces and the second inner peripheral surfaces that define the space into which the shaft is pressed in the press-fitting process is further improved, and the press-fitting allowance (Mp) of the shaft into the common insertion hole can be more reliably guaranteed. That is, according to the seventh fitting method, higher centering accuracy and fitting strength can be achieved in the fitting of the laminated core and the shaft, and therefore more reliable torque transmission can be achieved.

[0258] Twenty-second Embodiment Hereinafter, a fitting method between a laminated core and a shaft according to a twenty-second embodiment of the present invention (hereinafter, may be referred to as an "eighth fitting method") will be described.

[0259] The seventh laminate core configuration as described above can be combined with the second to sixth laminate core configurations described above. That is, as described individually in the description of the seventh laminate core, the seventh laminate core configuration can be applied to each of the second to sixth laminate core configurations. Among these, in the fourth laminate core to which the seventh laminate core configuration is applied, recesses are formed in the portions of the inner circumferential surfaces of the first and third insertion holes facing the first bent portions and the portions of the inner circumferential surfaces of the first and second insertion holes facing the second bent portions. Therefore, in the fitting structure between the fourth laminate core to which the seventh laminate core configuration is applied and the shaft, the first bent portion and / or the second bent portion can be at least partially immersed in the recesses. This makes it possible to more reliably reduce slippage between the laminate core and the shaft in the rotational direction, thereby achieving higher torque transmission performance.

[0260] As described above, the specific method for at least partially immersing the first bent portion and / or the second bent portion in the recess is not particularly limited. For example, the first bent portion and / or the second bent portion may be immersed in the recess during the process of forming the first bent portion and the second bent portion by bending the first protruding portion and the second protruding portion in the direction of the common axis in the bending process. Alternatively, the first bent portion and / or the second bent portion may be immersed in the recess during the process of pressing the shaft into the common insertion hole of the laminated core in the pressing process included in the method of fitting the laminated core and the shaft.

[0261] <composition> Therefore, the eighth fitting method is a method of fitting a laminated core and a shaft, in which the shaft is press-fitted into the common through-hole of the fourth laminated core to which the configuration of the seventh laminated core is applied. The eighth fitting method includes a press-fitting step of press-fitting the shaft into the common through-hole to sandwich the shaft between the first inner circumferential surfaces, which are surfaces of the first bent portions facing the common through-hole, and the second inner circumferential surfaces, which are surfaces of the second bent portions facing the common through-hole. Furthermore, in the eighth fitting method, the first bent portion and / or the second bent portion are at least partially immersed in the recess in the press-fitting step.

[0262] The fourth laminated core to which the seventh laminated core configuration is applied can be manufactured, for example, by the fourth method to which the seventh manufacturing method is applied. The configuration of the fourth laminated core to which the seventh laminated core configuration is applied has already been described in detail in the description of the fourth method to which the seventh manufacturing method is applied. Therefore, a detailed description of the eighth fitting method will be omitted.

[0263] <effect> As described above, in the eighth fitting method, the fourth laminated core to which the configuration of the seventh laminated core is applied is used as a laminated core having a common insertion hole into which the shaft is press-fitted, and the first bent portion and / or the second bent portion is at least partially immersed in the recess in the press-fitting step. Therefore, according to the eighth fitting method, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced, thereby achieving higher torque transmission performance. Twenty-second Embodiment Hereinafter, a fitting method between a laminated core and a shaft according to a 22nd embodiment of the present invention (hereinafter, may be referred to as a "ninth fitting method") will be described.

[0264] As described above in the explanation of the second and seventh fitting methods, depending on the application, such as in a rotating electric machine having a fitting structure between a laminated core and a shaft fitted by the fitting method of the present invention, higher torque transmission performance may be required.

[0265] <composition> Therefore, the ninth fitting method is the eighth fitting method described above, which is a method of fitting a laminated core and a shaft, further including a punching process of performing punching on the multiple first inner circumferential surfaces and the multiple second inner circumferential surfaces by inserting a punch into the common insertion hole before the pressing process.

[0266] As described above, the ninth fitting method has the same configuration as the eighth fitting method described above, except that the pressing step is performed before the press-fitting step. The pressing step has already been described in detail with reference to Figures 35 and 36 in the description of the second fitting method described above. Therefore, a detailed description of the eighth fitting method will be omitted.

[0267] <effect> As described above, in the ninth fitting method, the fourth laminated core to which the configuration of the seventh laminated core is applied is adopted as a laminated core having a common insertion hole into which the shaft is press-fitted, and the pressing step is performed before the press-fitting step. Therefore, in the ninth fitting method, the plate thickness of the first bent portion and the second bent portion can be made more uniform, and the first inner peripheral surface and the second inner peripheral surface can be made smoother. As a result, the dimensional accuracy of the first inner peripheral surfaces and the second inner peripheral surfaces that define the space into which the shaft is press-fitted in the press-fitting step is further improved, and the press-fitting allowance (Mp) of the shaft into the common insertion hole can be more reliably guaranteed. In other words, according to the ninth fitting method, higher centering accuracy and fitting strength can be achieved in the fitting of the laminated core and the shaft, and therefore more reliable torque transmission can be achieved.

[0268] Twenty-third embodiment Hereinafter, a fitting method between a laminated core and a shaft according to a twenty-second embodiment of the present invention (hereinafter, may be referred to as a "tenth fitting method") will be described.

[0269] As described above, in the fourth laminated core to which the seventh laminated core configuration is applied, recesses are formed in the portions of the inner circumferential surfaces of the first and third insertion holes facing the first bent portions and the portions of the inner circumferential surfaces of the first and second insertion holes facing the second bent portions. Therefore, in the fitting structure between the fourth laminated core to which the seventh laminated core configuration is applied and the shaft, the first bent portions and / or the second bent portions can be at least partially recessed into the recesses. This makes it possible to more reliably reduce slippage between the laminated core and the shaft in the rotational direction, thereby achieving higher torque transmission performance.

[0270] As described above, the specific method for at least partially immersing the first bent portion and / or the second bent portion in the recess is not particularly limited. For example, the first bent portion and / or the second bent portion may be immersed in the recess in a process of forming the first bent portion and the second bent portion by bending the first protruding portion and the second protruding portion in the direction of the common axis in a bending step included in the fourth manufacturing method to which the seventh manufacturing method is applied. Alternatively, the first bent portion and the second bent portion may be immersed in the recess in a process of pressing the shaft into the common insertion hole of the laminated core in a pressing step included in the fitting method between the fourth laminated core to which the seventh laminated core configuration is applied, as in the eighth fitting method described above. Furthermore, in the punching step included in the method of fitting a fourth laminated core to a shaft to which the configuration of the seventh laminated core is applied as in the ninth fitting method described above, the first bent portion and / or the second bent portion may be immersed in the recess during the process of punching the multiple first inner circumferential surfaces and the multiple second inner circumferential surfaces by inserting a punch into the common insertion hole of the laminated core.

[0271] <composition> Therefore, the tenth fitting method is the above-mentioned ninth fitting method, which is a method of fitting a laminated core and a shaft, in which the first bent portion and / or the second bent portion are at least partially immersed in the recess during the rolling process.

[0272] As described above, the tenth fitting method has the same configuration as the ninth fitting method described above, except that the first bent portion and / or the second bent portion is at least partially immersed in the recess in the rolling process performed before the press-fitting process. The fourth laminated core to which the seventh laminated core configuration is applied can be manufactured, for example, by the fourth method to which the seventh manufacturing method is applied. The configuration of the fourth laminated core to which the seventh laminated core configuration is applied has already been described in detail in the description of the fourth method to which the seventh manufacturing method is applied. The rolling process has already been described in detail in the description of the second fitting method described above, with reference to Figures 35 and 36. Therefore, a detailed description of the tenth fitting method will be omitted.

[0273] <effect> As described above, in the tenth fitting method, the first bent portion and / or the second bent portion is at least partially sunk into the recess in the squeezing step performed before the press-fitting step. Therefore, according to the tenth fitting method, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced, thereby achieving higher torque transmission performance.

[0274] Twenty-fifth Embodiment Hereinafter, a fitting method between a laminated core and a shaft according to a 25th embodiment of the present invention (hereinafter, may be referred to as an "eleventh fitting method") will be described.

[0275] As described above, in the fitting structure between the laminated core and the shaft, by accommodating a protrusion serving as a key provided on either the laminated core or the shaft into a key groove provided on the other, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced.

[0276] <composition> Therefore, the eleventh fitting method is a method for fitting a fifth laminated core to a shaft, to which the configuration of the fifth laminated core or the seventh laminated core described above is applied. The eleventh fitting method includes a press-fitting step of press-fitting the shaft into the common insertion hole and sandwiching the shaft between the first inner peripheral surfaces or between the first inner peripheral surfaces and the second inner peripheral surfaces. Furthermore, a key groove, which is a recess extending in a direction parallel to the common axis, is provided on one of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft, and a key, which is a protrusion extending in a direction parallel to the common axis, is provided on the other of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft. In addition, in the press-fitting step, the shaft is press-fitted into the common insertion hole so that the key is accommodated in the key groove.

[0277] The fifth laminated core to which the configurations of the fifth laminated core and the seventh laminated core are applied can be manufactured by, for example, the fifth manufacturing method and the fifth method to which the seventh method are applied, respectively. Note that, as the configurations of the fifth laminated core to which the configurations of the fifth laminated core and the seventh laminated core are applied have already been described in detail with reference to Figures 21 to 23 regarding the fifth manufacturing method and the fifth method to which the seventh method is applied, description thereof will be omitted here.

[0278] <effect> As is clear from the description of the effects achieved by the fifth manufacturing method to which the fifth and seventh manufacturing methods are applied and the fifth laminated core to which the configurations of the fifth and seventh laminated cores are applied, in the fifth laminated core to which the configurations of the fifth and seventh laminated cores are applied, a keyway which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on the inner peripheral surface of the common insertion hole. Therefore, in the press-fitting step included in the eleventh fitting method, a shaft having a key or a keyway formed on its outer peripheral surface corresponding to the keyway or key provided on the inner peripheral surface of the common insertion hole as described above can be press-fitted into the common insertion hole of the laminated core to accommodate the key in the keyway. As a result, the eleventh fitting method can more reliably reduce slippage between the laminated core and the shaft in the rotational direction.

[0279] Twenty-sixth Embodiment Hereinafter, a fitting method of a laminated core and a shaft according to a 26th embodiment of the present invention (hereinafter, may be referred to as a "twelfth fitting method") will be described.

[0280] As mentioned above, there is known a technique for reducing problems such as deterioration or destruction of insulation, burning, deterioration of bearings, and deterioration of lubricants such as grease, which are caused by heat generation accompanying the operation of rotating electric machines such as generators and electric motors, by supplying cooling oil from one end of the shaft and flowing the cooling oil through an oil passage provided inside the laminated core via the inside of the shaft to cool the shaft and the laminated core. Such a configuration can also be applied to the fitting method of the laminated core and the shaft according to the present invention.

[0281] <composition> Therefore, the twelfth fitting method is a method for fitting a sixth laminated core and a shaft to which the configuration of the sixth laminated core or the seventh laminated core described above is applied. The twelfth fitting method includes a press-fitting step of press-fitting the shaft into the common insertion hole and sandwiching the shaft between the first inner circumferential surfaces or between the first inner circumferential surfaces and the second inner circumferential surfaces. A first flow path for flowing a refrigerant is formed inside the laminated core, and a first opening communicating with the first flow path is provided on the inner circumferential surface of the common insertion hole. Furthermore, a second flow path for flowing a refrigerant is formed inside the shaft, and a second opening communicating with the second flow path is provided on the outer circumferential surface of the shaft. In addition, in the press-fitting step, the shaft is press-fitted into the common insertion hole so that the first opening and the second opening face each other and the first flow path and the second flow path are communicated with each other.

[0282] The sixth laminated core to which the configurations of the sixth laminated core and the seventh laminated core are applied can be manufactured by, for example, the sixth manufacturing method to which the sixth manufacturing method and the seventh manufacturing method described above are applied, respectively. Note that, as for the configuration of the sixth laminated core to which the configurations of the sixth laminated core and the seventh laminated core are applied, the sixth manufacturing method to which the sixth manufacturing method and the seventh manufacturing method described above are applied has already been described in detail with reference to Figs. 24 to 33, and therefore description thereof will be omitted here.

[0283] <effect> As is clear from the explanation of the effects achieved by the sixth method to which the sixth manufacturing method and the seventh method are applied, and the sixth laminated core to which the configurations of the sixth laminated core and the seventh laminated core are applied, in the sixth laminated core to which the configurations of the sixth laminated core and the seventh laminated core are applied, a first flow passage for flowing a refrigerant is formed inside the laminated core, and a first opening communicating with the first flow passage is provided on the inner peripheral surface of the common insertion hole. On the other hand, in the shaft used in the twelfth fitting method, a second flow passage for flowing a refrigerant is formed inside the shaft, and a second opening communicating with the second flow passage is provided on the outer peripheral surface of the shaft. Therefore, in the press-fitting step included in the twelfth fitting method, the shaft is press-fitted into the common insertion hole so that the first opening and the second opening face each other, thereby making it possible to communicate the first flow passage formed inside the laminated core with the second flow passage formed inside the shaft. As a result, the shaft and the laminated core can be effectively cooled by flowing a refrigerant inside the laminated core via the inside of the shaft. In other words, the twelfth fitting method can reduce problems such as deterioration or destruction of insulation, burning, deterioration of bearings, and deterioration of lubricants such as grease, which are caused by heat generation accompanying the operation of rotating electric machines such as generators and electric motors that have a fitted body of a laminated core and a shaft.

[0284] Twenty-seventh embodiment As described at the beginning of this specification, the present invention relates not only to a method for manufacturing a laminated core, a laminated core, and a method for fitting a laminated core to a shaft, but also to a fitting structure for the laminated core to a shaft.

[0285] Hereinafter, a fitting structure between a laminated core and a shaft according to a 27th embodiment of the present invention (hereinafter, may be referred to as a "first fitting structure") will be described.

[0286] <composition> The first fitting structure is a fitting structure between a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of any of the laminated cores according to the eighth embodiment of the present invention (first laminated core) to the laminated cores according to the eleventh embodiment of the present invention (fourth laminated core). In the first fitting structure, the shaft is sandwiched by a plurality of first inner circumferential surfaces, which are surfaces facing the common insertion hole of the plurality of first bent portions.

[0287] The first to fourth laminated cores can be manufactured, for example, by the manufacturing method for laminated cores according to the first embodiment of the present invention (first manufacturing method) to the manufacturing method for laminated cores according to the fourth embodiment of the present invention (fourth manufacturing method), respectively. The first fitting structure having the above-mentioned configuration can be achieved, for example, by the fitting method for a laminated core and a shaft according to the fifteenth embodiment of the present invention (first fitting method). Note that the configurations of the first to fourth laminated cores and the first fitting structure have already been described in detail with reference to Figs. 2 to 20 in the explanation of the first to fourth manufacturing methods, the first to fourth laminated cores, and the first fitting method, and therefore will not be described here.

[0288] <effect> As is clear from the explanation of the effects achieved by the first to fourth manufacturing methods, the first to fourth laminated cores, and the first fitting method, the first fitting structure allows the shaft to be press-fitted into the common insertion hole of the laminated core and clamped by the first bent portion. As a result, adhesion when the shaft is press-fitted into the common insertion hole of the laminated core and breakage of the insulating coating of the electromagnetic steel sheets that accompanies crimping of the electromagnetic steel sheets that make up the laminated core are reduced, thereby reducing eddy current loss and improving the fitting strength and centering accuracy between the laminated core and the shaft.

[0289] Twenty-eighth Embodiment Hereinafter, a fitting structure between a laminated core and a shaft according to a 28th embodiment of the present invention (hereinafter, may be referred to as a "second fitting structure") will be described.

[0290] <composition> The second fitting structure is a fitting structure between a laminated core and a shaft, in which the shaft is pressed into the common insertion hole of the fourth laminated core described above, and the first bent portion is at least partially immersed in the recess.

[0291] The fourth laminated core can be manufactured, for example, by the manufacturing method of the laminated core according to the fourth embodiment of the present invention (fourth manufacturing method). The second fitting structure having the above-mentioned configuration can be achieved, for example, by the fitting method of the laminated core and the shaft according to the seventeenth embodiment of the present invention (third fitting method) or the fitting method of the laminated core and the shaft according to the nineteenth embodiment of the present invention (fifth fitting method). The configuration of the fourth laminated core and the state in which the first bent portion is immersed in the recess have already been described in detail with reference to Figures 19 and 20 in relation to the fourth manufacturing method, the fourth laminated core, and the third fitting method, so a description thereof will be omitted here.

[0292] <effect> As is clear from the above description of the effects achieved by the fourth manufacturing method, the fourth laminated core, and the third fitting method, in the second fitting structure, the first bent portion is at least partially immersed in the recessed portion. Therefore, the second fitting structure can more reliably reduce slippage between the laminated core and the shaft in the rotational direction, thereby achieving higher torque transmission performance.

[0293] Twenty-ninth embodiment Hereinafter, a fitting structure between a laminated core and a shaft according to a 29th embodiment of the present invention (hereinafter, may be referred to as a "third fitting structure") will be described.

[0294] <composition> The third fitting structure is a fitting structure between the laminated core and the shaft, in which the shaft is press-fitted into the common insertion hole of the fifth laminated core. Furthermore, in the third fitting structure, a key groove, which is a recess extending in a direction parallel to the common axis, is provided on one of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft, and a key, which is a protrusion extending in a direction parallel to the common axis, is provided on the other of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft. In addition, in the third fitting structure, a key is accommodated in the key groove.

[0295] The fifth laminated core can be manufactured, for example, by the manufacturing method for a laminated core according to the fifth embodiment of the present invention (fifth manufacturing method). The third fitting structure having the above-mentioned configuration can be achieved, for example, by the fitting method for fitting a laminated core and a shaft according to the twenty-fifth embodiment of the present invention (eleventh fitting method). Note that the configuration of the fifth laminated core and the manner in which the key is accommodated in the key groove have already been described in detail with reference to Figures 21 to 23 for the fifth manufacturing method and the eleventh fitting method, so a description thereof will be omitted here.

[0296] <effect> As described above, in the third fitting structure, a key groove, which is a recess extending in a direction parallel to the common axis, is provided on one of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft, and a key, which is a protrusion extending in a direction parallel to the common axis, is provided on the other of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft. In addition, in the third fitting structure, a key is accommodated in the key groove. Therefore, as is clear from the above-mentioned description of the effects achieved by the fifth manufacturing method, the fifth laminated core, and the eleventh fitting method, the third fitting structure can more reliably reduce slippage between the laminated core and the shaft in the rotational direction.

[0297] Thirty Embodiment Hereinafter, a fitting structure between a laminated core and a shaft according to a thirtieth embodiment of the present invention (hereinafter, may be referred to as a "fourth fitting structure") will be described.

[0298] <composition> The fourth fitting structure is a fitting structure between the laminated core and the shaft, in which the shaft is press-fitted into the common insertion hole of the sixth laminated core. Furthermore, in the fourth fitting structure, a second flow passage for flowing the refrigerant is formed inside the shaft, and a second opening communicating with the second flow passage is provided on the outer circumferential surface of the shaft. In addition, in the fourth fitting structure, the first opening and the second opening face each other, and the first flow passage and the second flow passage communicate with each other.

[0299] The sixth laminated core can be manufactured, for example, by the manufacturing method of the laminated core according to the sixth embodiment of the present invention (sixth manufacturing method). The fourth fitting structure having the above-mentioned configuration can be achieved, for example, by the fitting method of the laminated core and the shaft according to the twenty-sixth embodiment of the present invention (twelfth fitting method). Note that the configuration of the sixth laminated core and the manner in which the first opening and the second opening face each other and the first flow path communicate with the second flow path have already been described in detail with reference to Figs. 24 to 28 with respect to the sixth manufacturing method, the sixth laminated core, and the twelfth fitting method, and therefore will not be described here.

[0300] <effect> As described above, in the fourth fitting structure, the first flow passage for the coolant is formed inside the laminated core, and the first opening communicating with the first flow passage is provided on the inner circumferential surface of the common insertion hole. Furthermore, in the fourth fitting structure, the second flow passage for the coolant is formed inside the shaft, and the second opening communicating with the second flow passage is provided on the outer circumferential surface of the shaft. In addition, in the fourth fitting structure, the first opening and the second opening face each other, and the first flow passage and the second flow passage communicate with each other. Therefore, as is clear from the explanation of the effects achieved by the sixth manufacturing method and the tenth fitting method, according to the fourth fitting structure, the shaft and the laminated core can be effectively cooled by flowing the coolant into the laminated core through the inside of the shaft. That is, according to the fourth fitting structure, problems such as deterioration or destruction of insulation, burning, deterioration of bearings, and deterioration of lubricants such as grease, which occur due to heat generation accompanying the operation of rotating electric machines such as generators and electric motors equipped with a fitting body of a laminated core and a shaft, can be reduced.

[0301] Thirty-first embodiment Hereinafter, a fitting structure between a laminated core and a shaft according to a thirty-first embodiment of the present invention (hereinafter, may be referred to as a "fifth fitting structure") will be described.

[0302] <composition> The fifth fitting structure is a fitting structure between a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of the laminated core (seventh laminated core) according to the above-mentioned fourteenth embodiment of the present invention. In the fifth fitting structure, the shaft is sandwiched between a plurality of first inner circumferential surfaces which are surfaces facing the common insertion hole of the plurality of first bent portions and a plurality of second inner circumferential surfaces which are surfaces facing the common insertion hole of the plurality of second bent portions.

[0303] The seventh laminated core can be manufactured, for example, by the manufacturing method for a laminated core according to the seventh embodiment of the present invention (seventh manufacturing method). The fifth fitting structure having the above-mentioned configuration can be achieved, for example, by the fitting method for a laminated core and a shaft according to the twentieth embodiment of the present invention (sixth fitting method). Note that the configurations of the seventh laminated core and the sixth fitting structure have already been described in detail in the explanations of the seventh manufacturing method, the seventh laminated core, and the sixth fitting method, and therefore will not be described here.

[0304] <effect> As is clear from the above description of the effects achieved by the seventh manufacturing method, the seventh laminated core, and the sixth fitting method, the fifth fitting structure allows the shaft to be pressed into the common through-hole of the seventh laminated core and to be clamped not only by the first bent portion but also by the second bent portion. As a result, adhesion during the press-fitting of the shaft into the common through-hole of the laminated core and breakage of the insulating coating of the electromagnetic steel sheets caused by the crimping process of the electromagnetic steel sheets constituting the laminated core are reduced, thereby reducing eddy current loss and improving the fitting strength and centering accuracy between the laminated core and the shaft. Furthermore, the second cores adjacent in the direction of the common axis are bound and fixed by the second bent portion, so that the entire laminated core is bound and fixed as a whole. In other words, according to the fifth fitting structure, there is no need to bind and fix adjacent second cores together by means such as crimping, which further reduces the number of places where crimping is performed, thereby further reducing the possibility of short circuits between the electromagnetic steel sheets and reliably reducing eddy current loss when used as a core for a rotating electric machine or the like.

[0305] Thirty-second embodiment Hereinafter, a fitting structure between a laminated core and a shaft according to a thirty-second embodiment of the present invention (hereinafter, may be referred to as a "sixth fitting structure") will be described.

[0306] <composition> The sixth fitting structure is a fitting structure between a laminated core and a shaft, in which the shaft is pressed into a common insertion hole of the fourth laminated core to which the configuration of the seventh laminated core described above is applied, and in which the first bent portion and / or the second bent portion are at least partially immersed in the recess.

[0307] The fourth laminated core to which the seventh laminated core configuration is applied can be manufactured by, for example, the manufacturing method for a laminated core according to the fourth embodiment of the present invention (fourth manufacturing method) to which the manufacturing method for a laminated core according to the seventh embodiment of the present invention (seventh manufacturing method) is applied. The sixth fitting structure having the above-mentioned configuration can be achieved by, for example, the fitting method for a laminated core and a shaft according to the nineteenth embodiment of the present invention (fifth fitting method) or the fitting method for a laminated core and a shaft according to the twenty-first embodiment of the present invention (seventh fitting method). The configuration of the fourth laminated core to which the seventh laminated core configuration is applied and the manner in which the first bent portion is immersed in the recess have already been described in detail in the explanation of the fourth manufacturing method to which the seventh manufacturing method is applied, the fourth laminated core to which the seventh laminated core configuration is applied, and the fifth fitting method, so that the explanation here will be omitted.

[0308] <effect> As is clear from the explanation of the effects achieved by the fourth manufacturing method to which the seventh manufacturing method is applied, the fourth laminated core to which the seventh laminated core configuration is applied, and the fifth and seventh fitting methods, in the sixth fitting structure, the first bent portion and / or the second bent portion are at least partially immersed in the recessed portion. Therefore, according to the sixth fitting structure, slippage between the laminated core and the shaft in the rotational direction can be more reliably reduced, thereby achieving higher torque transmission performance.

[0309] Thirty-third embodiment Hereinafter, a fitting structure between a laminated core and a shaft according to a thirty-third embodiment of the present invention (hereinafter, may be referred to as a "seventh fitting structure") will be described.

[0310] <composition> The seventh fitting structure is a fitting structure between a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of the fifth laminated core to which the seventh laminated core configuration described above is applied. Furthermore, in the seventh fitting structure, a key groove, which is a recess extending in a direction parallel to the common axis, is provided on one of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft, and a key, which is a protrusion extending in a direction parallel to the common axis, is provided on the other of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft. In addition, in the seventh fitting structure, a key is accommodated in the key groove.

[0311] The fifth laminated core to which the seventh laminated core configuration is applied can be manufactured by, for example, the manufacturing method for a laminated core according to the fifth embodiment of the present invention (fifth manufacturing method) to which the manufacturing method for a laminated core according to the seventh embodiment of the present invention (seventh manufacturing method) described above is applied. The seventh fitting structure having the above-mentioned configuration can be achieved by, for example, the fitting method for a laminated core and a shaft according to the twenty-fifth embodiment of the present invention (eleventh fitting method). Note that the configuration of the fifth laminated core to which the seventh laminated core configuration is applied and the manner in which the key is accommodated in the key groove have already been described in detail with reference to Figs. 21 to 23 for the fifth manufacturing method to which the seventh manufacturing method is applied and the fifth manufacturing method to which the seventh manufacturing method is applied, and the eleventh fitting method, so that the description here will be omitted.

[0312] <effect> As described above, in the seventh fitting structure, a key groove, which is a recess extending in a direction parallel to the common axis, is provided on one of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft, and a key, which is a protrusion extending in a direction parallel to the common axis, is provided on the other of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft. In addition, in the seventh fitting structure, a key is accommodated in the key groove. Therefore, as is clear from the explanation of the effects achieved by the fifth manufacturing method to which the seventh manufacturing method is applied, the fifth laminated core to which the configuration of the seventh laminated core is applied, and the eleventh fitting method, the seventh fitting structure can more reliably reduce slippage between the laminated core and the shaft in the rotational direction.

[0313] Thirty-fourth embodiment Hereinafter, a fitting structure between a laminated core and a shaft according to a thirty-fourth embodiment of the present invention (hereinafter, may be referred to as an "eighth fitting structure") will be described.

[0314] <composition> The eighth fitting structure is a fitting structure between a laminated core and a shaft, in which the shaft is press-fitted into a common through-hole of the sixth laminated core to which the seventh laminated core configuration described above is applied. Furthermore, in the eighth fitting structure, a second flow passage for flowing a refrigerant is formed inside the shaft, and a second opening communicating with the second flow passage is provided on the outer circumferential surface of the shaft. In addition, in the eighth fitting structure, the first opening and the second opening face each other, and the first flow passage and the second flow passage communicate with each other.

[0315] The sixth laminated core to which the seventh laminated core configuration is applied can be manufactured by, for example, the manufacturing method for a laminated core according to the sixth embodiment of the present invention (sixth manufacturing method) to which the manufacturing method for a laminated core according to the seventh embodiment of the present invention (seventh manufacturing method) described above is applied. The eighth fitting structure having the above-mentioned configuration can be achieved by, for example, the fitting method for a laminated core and a shaft according to the 26th embodiment of the present invention (twelfth fitting method). Note that the configuration of the sixth laminated core to which the seventh laminated core configuration is applied and the manner in which the first opening and the second opening face each other and the first flow path and the second flow path communicate with each other have already been described in detail with reference to Figs. 24 to 33 regarding the sixth manufacturing method to which the seventh manufacturing method is applied, the sixth laminated core to which the seventh laminated core configuration is applied, and the twelfth fitting method, and therefore will not be described here.

[0316] <effect> As described above, in the eighth fitting structure, the first flow path for the coolant is formed inside the laminated core, and the first opening communicating with the first flow path is provided on the inner circumferential surface of the common insertion hole. Furthermore, in the eighth fitting structure, the second flow path for the coolant is formed inside the shaft, and the second opening communicating with the second flow path is provided on the outer circumferential surface of the shaft. In addition, in the eighth fitting structure, the first opening and the second opening face each other, and the first flow path and the second flow path communicate with each other. Therefore, as is clear from the explanation of the effects achieved by the sixth manufacturing method to which the seventh manufacturing method is applied, the sixth laminated core to which the configuration of the seventh laminated core is applied, and the twelfth fitting method, according to the eighth fitting structure, the shaft and the laminated core can be effectively cooled by flowing the coolant into the laminated core via the inside of the shaft. In other words, the eighth fitting structure can reduce problems such as deterioration or destruction of insulation, burning, deterioration of bearings, and deterioration of lubricants such as grease, which are caused by heat generation accompanying the operation of rotating electric machines such as generators and electric motors that have an engagement between a laminated core and a shaft.

[0317] For the purpose of explaining the present invention, several embodiments having specific configurations have been described above, sometimes with reference to the attached drawings. However, the scope of the present invention should not be construed as being limited to these exemplary embodiments, and it goes without saying that appropriate modifications can be made within the scope of the claims and the matters described in the specification. [Explanation of symbols]

[0318] 10…First Core 11, 12, 13, 14, 15, 16, 17, 18, 19, 13S, 14S, 15S, 16S, 13D, 13A...First electromagnetic steel sheet 11a, 12a, 13a, 14a, 15a, 16a, 17a, 18a, 19a, 13Sa, 14Sa, 15Sa, 16Sa...First insertion hole 12c…Concave 19k…Convex part 20…Second Core 21, 22, 23, 24, 25, 22D…Second electromagnetic steel sheet 21a, 22a, 23a, 24a, 25a...Second insertion holes 21p, 22p, 23p, 24p, 25p...First protrusion 21b, 22b, 24b, 25b, 22Db...First bent portion 25k…protruding part F1: Base end of first protrusion F2,F3…Bending part 30…Laminated core 30a...Common insertion hole 30k…key 40…Shaft 40g…Key groove 51…Third electromagnetic steel sheet 51p…Second protrusion 51b, 51Db...Second bend 61…First flow path 61a, 61b...Through hole 62...First opening 62c…notch

Claims

1. A method for manufacturing a laminated core formed by laminating a plurality of electromagnetic steel sheets having insertion holes, comprising the steps of: a first lamination step of forming a first core by laminating a plurality of first electromagnetic steel sheets having first insertion holes such that the first insertion holes are coaxially connected to each other; a second lamination step of forming a second core by laminating a second electromagnetic steel sheet having a second insertion hole and a plurality of first protrusions spaced apart from each other and protruding inward from a periphery of the second insertion hole on at least one end surface of the first core such that the first insertion hole and the second insertion hole are coaxially connected to each other to form a common insertion hole that is one insertion hole, and forming the laminated core by a plurality of the second cores or one of the second cores stacked such that the common insertion holes of adjacent second cores are coaxially connected to each other; a bending step of bending the first protruding portions along a common axis that is a central axis of the common insertion hole to form a plurality of first bent portions; Including, A method for manufacturing a laminated core.

2. A method for manufacturing the laminated core according to claim 1, comprising the steps of: a partial bending step, prior to the bending step, of providing at least one first bent portion at at least a part of the first protruding portions, the first bent portion being a portion bent in the same direction or the opposite direction to a direction in which the first protruding portions are bent in the bending step to form the first bent portions; Further comprising: A method for manufacturing a laminated core.

3. A method for manufacturing the laminated core according to claim 1, comprising the steps of: The shape of the common insertion hole is a polygon or a star-shaped polygon, The first protrusion protrudes inward from a side at a periphery of the second insertion hole. A method for manufacturing a laminated core.

4. A method for manufacturing the laminated core according to claim 1, comprising the steps of: A recess is formed in a portion of an inner circumferential surface of the first insertion hole facing the first bent portion. A method for manufacturing a laminated core.

5. A method for manufacturing the laminated core according to claim 1, comprising the steps of: In the first lamination step, a third electromagnetic steel sheet having a third insertion hole and a plurality of second protrusions spaced apart from each other and protruding inward from a periphery of the third insertion hole is sandwiched between the plurality of first electromagnetic steel sheets constituting the first core such that the first insertion hole and the third insertion hole are coaxially connected to each other; In the second lamination step, the laminated core is formed by laminating a plurality of the second cores, each of which is formed by laminating the second electromagnetic steel plate on at least one end face of the first core, so that the first insertion hole, the second insertion hole, and the third insertion hole are coaxially connected to each other to form the common insertion hole, In the bending step, the first protruding portions are bent along a direction of the common axis to form a plurality of first bent portions, and the second protruding portions are bent along a direction of the common axis to form a plurality of second bent portions, The first folding portions and the second folding portions have different index angles around the common axis and do not overlap with each other, In the direction of the common axis, one of a first range, which is a range in which the first bent portion extends, and a second range, which is a range in which the second bent portion extends, at least partially overlaps with a plurality of the other ranges. A method for manufacturing a laminated core.

6. A method for manufacturing a laminated core according to claim 5, comprising the steps of: a partial bending process, prior to the folding process, in which at least one first bent portion is provided on at least a portion of the first protruding portions, the first bent portion being a portion bent in the same direction or the opposite direction to the direction in which the first protruding portions are bent in the folding process to form the first bent portions, and / or at least one second bent portion is provided on at least a portion of the second protruding portions, the second bent portion being a portion bent in the same direction or the opposite direction to the direction in which the second protruding portions are bent in the folding process to form the second bent portions; Further comprising: A method for manufacturing a laminated core.

7. A method for manufacturing a laminated core according to claim 5, comprising the steps of: The shape of the common insertion hole is a polygon or a star-shaped polygon, the first protrusion protrudes inward from a side at a periphery of the second insertion hole, the second protruding portion protrudes inward from a side at a periphery of the third insertion hole, In the bending step, the first protruding portion is bent along the direction of the common axis to form the first bent portion so as to face the portions corresponding to the sides of the inner circumferential surfaces of the first insertion hole and the third insertion hole, and the second protruding portion is bent along the direction of the common axis to form the second bent portion so as to face the portions corresponding to the sides of the inner circumferential surfaces of the first insertion hole and the second insertion hole. A method for manufacturing a laminated core.

8. A method for manufacturing a laminated core according to claim 5, comprising the steps of: A recess is formed in a portion of an inner circumferential surface of the first insertion hole and the third insertion hole facing the first bent portion, and / or a portion of an inner circumferential surface of the first insertion hole and the second insertion hole facing the second bent portion. A method for manufacturing a laminated core.

9. A laminated core formed by laminating a plurality of electromagnetic steel sheets having insertion holes, the laminated core is constituted by a first core formed by stacking a plurality of first electromagnetic steel sheets having first insertion holes so that the first insertion holes are coaxially connected to one another on at least one end face of the first core, and a second electromagnetic steel sheet having second insertion holes stacked so that the first insertion hole and the second insertion hole are coaxially connected to one another to form a common insertion hole that is a single insertion hole, or a plurality of the second cores stacked so that the common insertion holes of adjacent second cores are coaxially connected to one another, the second electromagnetic steel sheet includes a plurality of first bent portions bent at a periphery of the second insertion hole and extending in a direction of a common axis that is a central axis of the common insertion hole; Laminated core.

10. 10. The laminated core according to claim 9, At least one first bent portion is provided at at least a part of the first bent portions, the first bent portion being a portion bent in the same direction or the opposite direction to the bending direction of the first bent portions at a periphery of the second insertion hole. Laminated core.

11. 10. The laminated core according to claim 9, The shape of the common insertion hole is a polygon or a star-shaped polygon, The first bent portion extends from a side at a periphery of the second insertion hole. Laminated core.

12. 10. The laminated core according to claim 9, A recess is formed in a portion of an inner circumferential surface of the first insertion hole facing the first bent portion. Laminated core.

13. A laminated core according to any one of claims 9 to 12, a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on an inner peripheral surface of the common insertion hole; Laminated core.

14. A laminated core according to any one of claims 9 to 12, a first flow passage for flowing a coolant is formed inside the laminated core, and a first opening communicating with the first flow passage is provided on an inner circumferential surface of the common insertion hole; Laminated core.

15. 10. The laminated core according to claim 9, a third electromagnetic steel sheet having a third insertion hole is sandwiched between the first electromagnetic steel sheets constituting the first core such that the first insertion hole and the third insertion hole are coaxially connected to each other; the laminated core is formed by stacking a plurality of the second cores, each of which is formed by stacking the second electromagnetic steel sheet on at least one end face of the first core such that the first insertion hole, the second insertion hole, and the third insertion hole are coaxially connected to each other to form the common insertion hole, the third electromagnetic steel sheet includes a plurality of second bent portions bent at a periphery of the third insertion hole and extending in a direction of the common axis, The first folding portions and the second folding portions have different index angles around the common axis and do not overlap with each other, In the direction of the common axis, one of a first range in which the first bent portion extends and a second range in which the second bent portion extends at least partially overlaps with a plurality of the other ranges. Laminated core.

16. 16. The laminated core according to claim 15, At least one first bent portion is provided on at least a portion of the first bent portions, the first bent portion being a portion bent in the same direction or the opposite direction to the direction in which the first bent portions are bent at the periphery of the second insertion hole, and / or at least one second bent portion is provided on at least a portion of the second bent portions, the second bent portion being a portion bent in the same direction or the opposite direction to the direction in which the second bent portions are bent at the periphery of the third insertion hole. Laminated core.

17. 16. The laminated core according to claim 15, The shape of the common insertion hole is a polygon or a star-shaped polygon, the first bent portion extends from a side at a periphery of the second insertion hole, The second bent portion extends from a side at a periphery of the third insertion hole. Laminated core.

18. 16. The laminated core according to claim 15, A recess is formed in a portion of an inner circumferential surface of the first insertion hole and the third insertion hole facing the first bent portion, and / or a portion of an inner circumferential surface of the first insertion hole and the second insertion hole facing the second bent portion. Laminated core.

19. A laminated core according to any one of claims 15 to 18, a key groove which is a recess extending in a direction parallel to the common axis or a key which is a protrusion extending in a direction parallel to the common axis is provided on an inner peripheral surface of the common insertion hole; Laminated core.

20. A laminated core according to any one of claims 15 to 18, a first flow passage for flowing a coolant is formed inside the laminated core, and a first opening communicating with the first flow passage is provided on an inner circumferential surface of the common insertion hole; Laminated core.

21. A method for fitting a laminated core and a shaft, comprising press-fitting the shaft into the common insertion hole of the laminated core according to any one of claims 9 to 12, a press-fitting step of press-fitting the shaft into the common insertion hole to sandwich the shaft between a plurality of first inner circumferential surfaces, which are surfaces of the plurality of first bent portions facing the common insertion hole, A method for fitting a laminated core to a shaft.

22. A method for fitting a laminated core and a shaft according to claim 21, comprising the steps of: Prior to the pressing step, a punching step of inserting a punch through the common insertion hole to perform a punching process on the first inner circumferential surfaces; Further comprising: A method for fitting a laminated core to a shaft.

23. 13. A method for fitting a laminated core and a shaft, comprising press-fitting the shaft into the common insertion hole of the laminated core according to claim 12, a press-fitting step of press-fitting the shaft into the common insertion hole to sandwich the shaft between a plurality of first inner circumferential surfaces of the plurality of first bent portions, the first inner circumferential surfaces being surfaces facing the common insertion hole; In the press-fitting step, the first bent portion is at least partially inserted into the recess. A method for fitting a laminated core to a shaft.

24. A method for fitting a laminated core and a shaft according to claim 23, comprising the steps of: Prior to the pressing step, a punching step of inserting a punch through the common insertion hole to perform a punching process on the first inner circumferential surfaces; Further comprising: A method for fitting a laminated core to a shaft.

25. A method for fitting a laminated core and a shaft according to claim 24, comprising the steps of: In the squeezing step, the first bent portion is at least partially immersed in the recess. A method for fitting a laminated core to a shaft.

26. A method for fitting a shaft to a laminated core according to any one of claims 15 to 18, comprising press-fitting a shaft into the common insertion hole of the laminated core, the method comprising: a press-fitting step of press-fitting the shaft into the common insertion hole to sandwich the shaft between a plurality of first inner circumferential surfaces which are surfaces of the plurality of first bent portions facing the common insertion hole and a plurality of second inner circumferential surfaces which are surfaces of the plurality of second bent portions facing the common insertion hole, A method for fitting a laminated core to a shaft.

27. A method for fitting a laminated core and a shaft according to claim 26, comprising the steps of: Prior to the pressing step, a punching process for punching the first inner circumferential surfaces and the second inner circumferential surfaces by inserting a punch through the common insertion hole; Further comprising: A method for fitting a laminated core to a shaft.

28. A method for fitting a laminated core and a shaft, comprising press-fitting the shaft into the common insertion hole of the laminated core according to claim 18, comprising the steps of: a press-fitting step of press-fitting the shaft into the common insertion hole to sandwich the shaft between a plurality of first inner circumferential surfaces which are surfaces of the plurality of first bent portions facing the common insertion hole and a plurality of second inner circumferential surfaces which are surfaces of the plurality of second bent portions facing the common insertion hole, In the press-fitting step, the first bent portion and / or the second bent portion is at least partially inserted into the recess. A method for fitting a laminated core to a shaft.

29. A method for fitting a laminated core and a shaft according to claim 28, comprising the steps of: Prior to the pressing step, a punching process for punching the first inner circumferential surfaces and the second inner circumferential surfaces by inserting a punch through the common insertion hole; Further comprising: A method for fitting a laminated core to a shaft.

30. 30. A method for fitting a laminated core and a shaft according to claim 29, comprising the steps of: In the squeezing step, the first bent portion and / or the second bent portion are at least partially immersed in the recess. A method for fitting a laminated core to a shaft.

31. A fitting structure between a laminated core and a shaft, in which a shaft is press-fitted into the common insertion hole of the laminated core according to any one of claims 9 to 12, the shaft is sandwiched by a plurality of first inner circumferential surfaces which are surfaces of the plurality of first bent portions facing the common insertion hole; A fitting structure between a laminated core and a shaft.

32. A fitting structure between a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of the laminated core according to claim 12, The first bent portion is at least partially embedded in the recess. A fitting structure between a laminated core and a shaft.

33. A fitting structure between a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of the laminated core according to claim 13, a key groove, which is a recess extending in a direction parallel to the common axis, is provided on one of an inner peripheral surface of the laminated core and an outer peripheral surface of the shaft; a key, which is a protrusion extending in a direction parallel to the common axis, is provided on the other of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft; The key is received in the key groove. A fitting structure between a laminated core and a shaft.

34. A fitting structure between a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of the laminated core according to claim 14, a second flow passage for flowing the coolant is formed inside the shaft, and a second opening communicating with the second flow passage is provided on an outer circumferential surface of the shaft; The first opening and the second opening face each other, and the first flow path and the second flow path are in communication with each other. A fitting structure between a laminated core and a shaft.

35. A fitting structure between a laminated core and a shaft, the fitting structure being formed by press-fitting a shaft into the common insertion hole of the laminated core according to any one of claims 15 to 18, the shaft is sandwiched between a plurality of first inner circumferential surfaces which are surfaces of the plurality of first bent portions facing the common insertion hole and a plurality of second inner circumferential surfaces which are surfaces of the plurality of second bent portions facing the common insertion hole, A fitting structure between a laminated core and a shaft.

36. 19. A fitting structure between a laminated core and a shaft, in which a shaft is press-fitted into the common insertion hole of the laminated core according to claim 18, The first folded portion and / or the second folded portion are at least partially embedded in the recess. A fitting structure between a laminated core and a shaft.

37. 20. A fitting structure between a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of the laminated core according to claim 19, a key groove, which is a recess extending in a direction parallel to the common axis, is provided on one of an inner peripheral surface of the laminated core and an outer peripheral surface of the shaft; a key, which is a protrusion extending in a direction parallel to the common axis, is provided on the other of the inner peripheral surface of the laminated core and the outer peripheral surface of the shaft; The key is received in the key groove. A fitting structure between a laminated core and a shaft.

38. 21. A fitting structure between a laminated core and a shaft, in which the shaft is press-fitted into the common insertion hole of the laminated core according to claim 20, a second flow passage for flowing the coolant is formed inside the shaft, and a second opening communicating with the second flow passage is provided on an outer circumferential surface of the shaft; The first opening and the second opening face each other, and the first flow path and the second flow path are in communication with each other. A fitting structure between a laminated core and a shaft.

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