Method for manufacturing stator core

Abstract

Provided is a method for manufacturing a stator core capable of efficiently manufacturing a stator core of a rotating electrical machine provided with a flow path for a cooling medium. A method for manufacturing a stator core includes: a first step (S1) in which a predetermined portion (11a) of a core to be formed as a core portion (11) in a slot-corresponding portion of a stator core is formed with respect to an electromagnetic steel sheet, and a notching process for predetermined push-back is performed; a second step (S2) for forming a core section (11) by pushing back and returning the core-to-form portion (11a), which has been notched in the first step (S1), to a position prior to the first step (S1); a third step (S3) for forming a laminate (10a) by laminating the electromagnetic steel sheets (10) having the core section (11) formed by the second step (S2); a fourth step (S4) in which a stator inner peripheral cover (9), which is a component to be integrated with the stator core (1), is molded on the laminated body (10a) formed in the third step (S3); and a fifth step (S5) in which, subsequent to the fourth step (S4), the core part (11) is removed from the laminate (10a).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a stator core. Background Art

[0002] The stator core of a rotating electrical machine is constructed by stacking electromagnetic steel sheets machined into a corresponding shape. Cooling is sometimes achieved by circulating a coolant through the slots of this stator core. In this method, an annular stator inner circumferential cover is installed along the inner circumference of the stator core to seal the inner circumferential openings of each slot, preventing the coolant flowing axially through the slots while cooling the coil conductors from leaking into the gap between the stator core and the rotor.

[0003] On the one hand, a method for manufacturing a stator core has been proposed, wherein the stator core of a rotating electrical machine is divided into a plurality of blocks in the circumferential direction, each having a predetermined angular dimension, and the plurality of blocks are fastened to each other in an annular shape via dummy caulking blocks, and the dummy caulking blocks are subsequently removed (see Patent Document 1).

[0004] Meanwhile, recent years have seen active development of electrification technologies in the vehicle sector as part of efforts to achieve a low-carbon or decarbonized society. The electrification of vehicles demands highly energy-efficient rotating electrical machines. To commercialize these rotating electrical machines, a method for manufacturing stator cores that achieves high yield and, consequently, energy savings is required.

[0005] [Prior Art Literature]

[0006] (Patent Document)

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-111865 Summary of the Invention

[0008] [Problems to be solved by the invention]

[0009] However, the method disclosed in Patent Document 1 cannot be directly applied as a method for molding a stator inner peripheral cover that seals the opening on the inner peripheral side of each slot to prevent the coolant of the stator core from leaking into the gap with the rotor.

[0010] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method for manufacturing a stator core that can efficiently manufacture a stator core of a rotating electric machine having a flow path for a cooling medium, thereby contributing to improvement in energy efficiency.

[0011] [Technical means to solve the problem]

[0012] (1) A method for manufacturing a stator core, comprising: a first step (e.g., first step S1 described later) of performing a predetermined push-back cutting process on a predetermined core forming portion (e.g., predetermined core forming portion 11a described later) of a material of a stator core (e.g., stator core 1 described later) formed with a plurality of slots (e.g., slots 3 described later) of an electromagnetic steel sheet (e.g., electromagnetic steel sheet 10 described later) corresponding to the slots, which will later serve as a core portion (e.g., core portion 11 described later); and a second step (e.g., second step S2 described later) of performing a predetermined push-back cutting process on the core forming portion (e.g., predetermined core forming portion 11a described later) of the stator core (e.g., stator core 1 described later) formed with a plurality of slots (e.g., slots 3 described later); The stator portion is pushed back and restored to the position before the first step to form the core portion; a third step (for example, the third step S3 described later) is to stack the electromagnetic steel sheets that have formed the core portion by the second step to form a stacked body (for example, the stacked body 10a described later); a fourth step (for example, the fourth step S4 described later) is to mold a part to be integrated with the stator core (for example, the stator inner circumferential cover 9 described later) on the stacked body formed in the third step; and a fifth step (for example, the fifth step S5 described later) is to remove the core portion from the stacked body after the fourth step.

[0013] (2) A method for manufacturing a stator core according to (1) above, wherein in the first step, a predetermined push-back cut is performed on the electromagnetic steel sheet at a predetermined portion for forming the core, and on the other hand, a portion of the outer contour of the stator core is punched out.

[0014] (3) A method for manufacturing a stator core according to (1) or (2) above, wherein the core portion formed in the second step has a closed shape portion (for example, the closed shape portion 11b described later), which covers the opening portion of the slot toward the inner periphery of the stator core.

[0015] (4) The method for manufacturing a stator core according to (3) above, wherein the planar projection outer shape of the core portion itself formed in the second step is smaller than the planar projection outer shape of the slot.

[0016] (5) The method for manufacturing a stator core according to (4) above, wherein the core portion formed in the second step has a void (for example, a void 11 c described later) formed in its own planar projection outer shape.

[0017] (6) A method for manufacturing a stator core according to (1) above, wherein the part formed in the fourth step is a stator inner circumferential cover, which covers the inner circumferential surface of the stator core and constitutes a cooling medium flow path (for example, the cooling medium flow path 8 in the slot described later) of a rotating electrical machine having the stator core.

[0018] (Effects of the Invention)

[0019] In the stator core manufacturing method (1) described above, the predetermined portion to be the core portion, which has been subjected to the predetermined push-back cutout processing in the first step, is pushed back to the position before the first step in the second step to form the core portion. Therefore, the dimensions of the opening on the inner circumference side of the corresponding slot match the dimensions of the corresponding portion of the core portion with high precision. Therefore, by using a mold for this core portion, the portion that closes the opening on the inner circumference side of the slot in the component to be integrated with the stator core can be formed with sufficient precision.

[0020] In the stator core manufacturing method of (2) above, in the first step, the electromagnetic steel sheet is subjected to a predetermined push-back cut at the portion where the core is to be formed, and the outer contour portion of the stator core is blanked. Therefore, the stator core can be manufactured efficiently.

[0021] In the stator core manufacturing method of (3) above, the core portion formed in the second step includes a blocking portion that covers the slot openings facing the inner circumference of the stator core. Therefore, by using a mold having a core blocking portion whose dimensions precisely match the dimensions of the slot openings, the portion that blocks the slot openings on the inner circumference of the component to be integrated with the stator core can be formed with sufficient accuracy.

[0022] In the manufacturing method of the stator core described in (4) above, the plane projection shape of the core portion formed in the second step is smaller than the plane projection shape of the slot, and therefore, it is easy to remove the core portion after the molding is completed in the fourth step.

[0023] In the stator core manufacturing method of the above (5), the core portion formed in the second step has a space formed in its own planar projection shape, so it is easy to remove the core portion after the molding in the fourth step is completed.

[0024] In the stator core manufacturing method of (6) above, the component formed in the fourth step is a stator inner circumferential cover, which covers the inner circumferential surface of the stator core and constitutes a cooling medium flow path for a rotating electric machine having this stator core. Therefore, a rotating electric machine can be realized in which the portion of the stator inner circumferential cover that closes the opening on the inner circumference side of the slot has high dimensional accuracy, and the cooling medium does not leak into the gap between the stator core and its corresponding rotor.

[0025] In summary, (1) to (6) above show that according to the method for manufacturing a stator core disclosed in the present invention, the stator core of a rotating electrical machine can be manufactured efficiently, thereby contributing to the improvement of energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an exploded schematic diagram of a rotating electrical machine including a stator core manufactured by the stator core manufacturing method according to an example of the present disclosure.

[0027] Figure 2 This is a process diagram illustrating a method for manufacturing a stator core according to an example of the present disclosure.

[0028] Figure 3 Yes Figure 2 A diagram illustrating each stage from the first step to the fourth step in FIG.

[0029] Figure 4 It is shown in Figure 2 FIG. 1 is a diagram of a core formed in the second step in FIG.

[0030] Figure 5 It is shown in Figure 2 A diagram showing the relationship between the core formed in the second step and the stator inner cover molded in the fourth step.

[0031] Figure 6 Yes Figure 2 A diagram illustrating each stage in the fifth step.

[0032] Figure 7 It is a drawing Figure 2 FIG. 5 is a diagram showing the core removal operation in the fifth step.

[0033] Figure 8 It is a drawing Figure 2 A diagram of the slots and the stator inner cover at the end of the fifth step.

[0034] Figure 9 It is shown in Figure 2 FIG. 1 is a diagram showing a state in which stator coils are arranged in slots in a state in which the fifth step in FIG. 1 is completed. DETAILED DESCRIPTION

[0035] Hereinafter, the manufacturing method of the stator core of the present disclosure will be described with reference to the drawings. In each of the following drawings, corresponding parts are denoted by the same reference numerals.

[0036] Figure 1 This schematic diagram shows an exploded view of a rotating electrical machine 2 having a stator core 1 manufactured using a stator core manufacturing method according to an example of the present disclosure. The stator core 1 has an annular cross-section perpendicular to the central axis of the rotating electrical machine 2. Multiple slots 3 are arranged circumferentially and evenly spaced in the stator core 1. Multiple flat conductors 4 are disposed in each of the slots 3. The flat conductors 4, each having a rectangular cross-section (square conductor), are electrically connected at their ends to form a stator coil 5.

[0037] At the axial front end portion ( Figure 1 The front side is the middle side) and the axial rear end side ( Figure 1 (The center is the depth side) An annular front cover member 6 and rear cover member 7 are mounted to cover the front and rear ends of the stator coil 5. The front and rear cover members 6 and 7 house the connecting conductors at the front and rear ends of the stator coil 5 and form part of the flow path for the cooling medium.

[0038] That is, the cooling medium introduced into the front cover member 6 from the discharge side of the cooling medium pump (not shown) circulates in a loop inside the front cover member 6 and reaches the rear cover member 7 through the in-slot cooling medium flow path 8 formed between the flat conductors 4 in the slot 3 and between the flat conductors 4 and the inner wall of the slot 3, thereby forming a cooling medium circulation system that circulates through the cooling medium circulation channel (not shown).

[0039] An annular stator inner cover 9 is provided along the inner circumference of the stator core 1. The stator inner cover 9 is provided to prevent the cooling medium in the slot cooling medium flow path 8, which flows axially in the slot 3, from leaking into the gap with the rotor (not shown) while cooling the flat conductors 4. As will be described later, the stator inner cover 9 is molded along the inner circumference of the stator core 1. Figure 1 In the figure, the stator inner cover 9 is schematically shown at a position pulled out axially forward from the stator core 1 for the convenience of illustrating its outer shape.

[0040] Figure 2 It is a process diagram showing a method for manufacturing the stator core 1 according to an example of the present disclosure. Figure 3 Yes Figure 2 A diagram illustrating each stage from the first step S1 to the fourth step S4 in FIG. Figure 4 It is shown in Figure 2 Figure 2 shows the core formed in the second step S2. Figure 2 、 Figure 3 and Figure 4 The following describes each step from the first step S1 to the fourth step S4. In the first step S1, the electromagnetic steel sheet 10, which is the material of the stator core 1, is punched out to define the outer and inner peripheries of the stator core 1 in planar projection. Furthermore, a predetermined push-back cut is performed on the core forming portion 11a, which will later become the core portion 11.

[0041] That is, Figure 3As shown in part (a), the material of the stator core 1, which has multiple slots 3 formed therein, is subjected to a predetermined push-back cutout at the locations 3a corresponding to the slots, which will later become the core portion 11, of the electromagnetic steel sheet 10. This cutout is a special form of stamping, but it is itself a well-known method for processing sheet metal. Furthermore, the portions within the slots 3 other than the predetermined core-forming portions 11a are blanked out to conform to the shape of the slots 3.

[0042] In the second step S2 following the first step S1, the core portion 11 is formed by pushing back. Thus, the main surface of the core portion 11 is flush with the electromagnetic steel sheet 10 before processing.

[0043] like Figure 4 As shown, the core portion 11 is formed so that its outer contour is spaced inward from the inner contour of the slot 3 of the stator core 1. The slot 3, which opens into the gap between the inner periphery of the stator core 1 and the outer periphery of the rotor (not shown), and the core portion 11, which closes this opening 3b, are seamlessly connected by a cutout with pushback.

[0044] In this example, the core portion 11 has a cavity 11c formed radially outward of the closed portion 11b relative to the stator core 1. This cavity 11c is formed by punching the electromagnetic steel sheet 10. The portions circumferentially adjacent to the slots 3 formed in the electromagnetic steel sheet 10 as described above constitute the teeth 17 of the rotating electrical machine 2. Furthermore, the stator core 1 in this example has radially recessed portions 17c on its inner circumferential surface corresponding to the openings 3b of the slots 3.

[0045] Then, in the third step S3, as Figure 3 As shown in part (b) of FIG. 1 , the electromagnetic steel sheets 10 having the core portion 11 formed therein in the second step S2 are stacked to form a stacked body 10 a to be the stator core 1 .

[0046] Furthermore, in the fourth step S4, as Figure 3 As shown in part (c) of FIG. 1 , the stator inner cover 9 , which is a component to be integrated with the stator core 1 , is molded on the laminate 10 a formed in the third step S3 .

[0047] Molding is performed as follows. Inside the laminate 10a, an inner diameter mold 12 having a diameter slightly larger than that of the rotor (not shown) of the rotary electric machine 2 and longer in the axial direction is arranged coaxially with the laminate 10a (coaxially with the stator core 1). At both ends of the inner diameter mold 12, a front split mold 13 and a rear split mold 14 are arranged so as to face each other in the axial direction. In this arrangement, the ends of the inner diameter mold 12 are fitted and clamped into the respective facing recesses of the front split mold 13 and the rear split mold 14, and the laminate 10a is axially (in the axial direction). Figure 3 (c) of the embodiment, the load is applied in a compressive manner in the up and down directions).

[0048] like Figure 3 As shown in part (c) of FIG. 1 , a cavity 15 corresponding to the stator inner peripheral cover 9 is formed between the outer periphery of the inner diameter die 12 and the inner periphery of the laminate 10a. Figure 3 The portion (c) of the mold cavity 15 is formed in the front split mold 13. Figure 3 The portion (c) of the rear split mold 14 is formed in the rear split mold 14. Furthermore, a runner 16 is formed in the rear split mold 14, communicating with the cavity 15. Molten resin 9a is injected into the cavity 15 through the runner 16 to mold the stator inner peripheral cover 9.

[0049] Figure 5 It is shown in Figure 2 FIG. 1 shows the relationship between the core portion 11 formed in the second step and the stator inner circumferential cover 9 molded in the fourth step S4. As described above, when the front split mold 13 and the rear split mold 14 are used to clamp the laminate 10a and apply an axial compressive load, a sufficiently large load is applied to prevent the core portion 11 from moving radially outward due to the injection pressure of the molten resin 9a. Thus, even if Figure 5 The boundary between the closed portion 11b of the core 11 and the opening 3b of the slot 3 is weakened by the half-punching process. This allows the core 11 (closed portion 11b) to maintain its position against the injection pressure of the molten resin 9a. This prevents the molten resin 9a from seeping into the slot 3, allowing the stator inner cover 9 to be molded in a properly shaped form.

[0050] If in Figure 2 In the fourth step S4, the molding of the stator inner cover 9 is completed, and then in the next fifth step S5, the core part 11 is removed from the laminate 10a. Figure 6 、 Figure 7 and Figure 8 , the fifth step S5 is described. Figure 6 This is a diagram for explaining each stage in the fifth step S5. Figure 7It is a diagram showing the removal operation of the core portion 11 in the fifth step S5. Figure 8 This is a diagram showing the slots 3 and the stator inner peripheral cover 9 in a state where the fifth step S5 is completed.

[0051] In the fifth step S5, first, Figure 6 As shown in part (a), the inner diameter mold 12, the front split mold 13, and the rear split mold 14 are removed. Thus, the stator inner peripheral cover 9 is provided along the inner peripheral surface of the laminated body 10a to be the stator core 1. At this stage, the core part 11 is left in the slot 3 (see Figure 5 Then, the core 11 is pulled so as to move radially outward in the slot 3. Figure 7 As shown, the weakened portion of the boundary between the closed shape portion 11b of the core portion 11 and the opening portion 3b of the slot 3 is easily torn apart, and the core portion 11 is separated from the opening portion 3b and the stator inner peripheral cover 9, as shown in FIG. Figure 6 When the core portion 11 is pulled toward the outer periphery as described above, the active end of the tool may be inserted and hooked in the empty space 11c and moved.

[0052] like Figure 7 and Figure 6 As shown in part (b), the core portion 11 is moved toward the outer peripheral side in the slot 3 and separated from the opening 3b and the stator inner peripheral cover 9. Figure 6 As shown in the (c) portion of the embodiment, the axial movement is removed. Figure 5 The core portion 11 is pressed into a block shape and is removed by moving in a unified posture. If the core portion 11 is removed, Figure 6 As shown in part (d) of FIG. 1 , the stator core 1 is in a completed shape. In this state, the slots 3 of the stator core 1 formed by the laminate 10a are as shown in FIG. Figure 8 As shown, the opening 3b is sealed by a protruding portion 9p formed on the outer periphery of the stator inner cover 9. In this example, the protruding portion 9p of the stator inner cover 9 fits seamlessly into the recessed portions 17c of the teeth 17 on both sides of the opening 3b of the slot 3. This prevents unnecessary relative movement between the inner circumference of the stator core 1 and the stator inner cover 9.

[0053] Figure 9This diagram shows stator coils 5 composed of flat conductors 4 arranged in slots 3 of stator core 1, after the completion of the fifth step S5. In this state, a coolant flows axially through in-slot coolant flow paths 8 formed between the flat conductors 4 and between the flat conductors 4 and the inner walls of the slots 3, which are sealed by stator inner circumferential covers 9. This flow of coolant promotes cooling of the stator coils 5 and stator core 1.

[0054] The above-described method for manufacturing the stator core in the present disclosure can be summarized as follows.

[0055] (1) In one aspect of the present disclosure, a method for manufacturing a stator core 1 includes: a first step S1 of performing a predetermined push-back cutting process on a predetermined core forming portion 11a, which will later serve as a core portion 11, at a portion 3a corresponding to the slots 3 of an electromagnetic steel sheet 10, a material of the stator core 1 having a plurality of slots 3; a second step S2 of pushing back and restoring the predetermined core forming portion 11a, which has been cut in the first step S1, to a position before the first step S1, thereby forming the core portion 11; a third step S3 of stacking the electromagnetic steel sheets 10, which have formed the core portion 11 in the second step S2, to form a laminate 10a; a fourth step S4 of molding a part (a stator inner circumferential cover 9) to be integrated with the stator core 1, on the laminate 10a formed in the third step S3; and a fifth step S5 of removing the core portion 11 from the laminate 10a following the fourth step S4.

[0056] In the manufacturing method of the stator core 1 described in (1), the predetermined portion to be the core portion, that is, the predetermined core forming portion 11a, which is half-punched in the first step S1, is restored to its original position before the half-punching in the first step S1 in the second step S2 to form the core portion 11. Therefore, the size of the opening 3b on the inner circumference side of the corresponding slot 3 is highly accurately consistent with the size of the corresponding portion of the core portion 11. Therefore, by using a mold for this core portion 11, the portion (the closed shape portion 11b) that closes the opening 3b on the inner circumference side of the slot 3 in the part (the stator inner circumference cover 9) to be integrated with the stator core 1 can be formed with sufficient accuracy.

[0057] (2) In the method for manufacturing the stator core 1 according to one aspect of the present disclosure, in the first step S1, the core forming portion 11a of the electromagnetic steel sheet 10 is semi-punched, and the outer contour portion of the stator core 1 is blanked. Therefore, the stator core can be manufactured efficiently.

[0058] (3) In the method for manufacturing the stator core 1 according to one aspect of the present disclosure, the core portion 11 formed in the second step S2 includes the blocking portion 11b that covers the opening 3b of the slot 3 facing the inner circumference of the stator core 1. Therefore, by using a mold for the blocking portion 11b of the core portion 11 having a size that precisely matches the size of the opening 3b of the slot 3, the portion that blocks the opening 3b on the inner circumference of the slot 3 in the component (stator inner circumferential cover 9) to be integrated with the stator core 1 can be formed with sufficient accuracy.

[0059] (4) In the method for manufacturing the stator core 1 according to one aspect of the present disclosure, the core portion 11 formed in the second step S2 has a planar projection shape smaller than the planar projection shape of the slots 3. Therefore, the removal of the core portion 11 after the molding is completed in the fourth step S4 is facilitated.

[0060] (5) In the manufacturing method of the stator core 1 according to one aspect of the present disclosure, the core portion 11 formed in the second step S2 has a void 11c formed within its own planar projection. Therefore, after the molding is completed in the fourth step S4, when removing the core portion 11, operations such as inserting the working end of a tool into the void 11c are easily performed.

[0061] (6) In the method for manufacturing the stator core 1 according to one aspect of the present disclosure, the component (stator inner circumferential cover 9) formed in the fourth step S4 is the stator inner circumferential cover 9, which covers the inner circumferential surface of the stator core 1 and constitutes a cooling medium flow path for the rotating electrical machine 2 having the stator core 1. Therefore, a rotating electrical machine 2 can be realized in which the portion of the stator inner circumferential cover 9 that closes the opening 3 b on the inner circumferential side of the slot 3 has high dimensional accuracy, and the cooling medium does not leak into the gap between the stator core 1 and its corresponding rotor.

[0062] The above description focuses on one embodiment of the stator core manufacturing method disclosed herein, but the technical concept of the present disclosure is not limited thereto. The structural details may be appropriately modified within the scope of the technical concept of the present disclosure. For example, instead of using a core portion having a void, a core portion may be used that lacks a void and has a concave or convex portion in its planar projection that facilitates the engagement of the tool's active end.

[0063] Reference numerals

[0064] 1: Stator core

[0065] 2: Rotating motor

[0066] 3: Slot

[0067] 3a: Slot corresponding part

[0068] 3b: Opening

[0069] 4: Flat conductor

[0070] 5: Stator coil

[0071] 6: Front side cover parts

[0072] 7: Rear cover parts

[0073] 8: Cooling medium flow path in the slot

[0074] 9: Stator inner cover

[0075] 9a: Molten resin

[0076] 9p: Protruding shape

[0077] 10: Magnetic steel plate

[0078] 10a: Laminated body

[0079] 11: Core

[0080] 11a: Core forming predetermined part

[0081] 11b: Occluded shape

[0082] 11c: Empty Space

[0083] 12: Inner diameter die

[0084] 13: Front split mold

[0085] 14: Rear split mold

[0086] 15: Cavity

[0087] 16: Runner

[0088] 17: Teeth

[0089] 17c: Concave shape portion

Claims

1. A method for manufacturing a stator core, comprising: In the first step, a predetermined push-back cut is performed on a predetermined portion of the core forming part of the electromagnetic steel sheet, which is a material of the stator core having a plurality of slots formed therein, at a portion corresponding to the slots and which will later serve as the core portion. The second step is to push back and restore the core formed at a predetermined portion after the cutting process in the first step to the position before the first step, thereby forming the core portion; A third step is to stack the electromagnetic steel sheets formed into the core portion in the second step to form a stacked body; A fourth step is to mold a part to be integrated with the stator core on the laminate formed in the third step; and The fifth step is to remove the core portion from the stacked body following the fourth step.

2. The method for manufacturing a stator core according to claim 1, wherein: In the first step, the electromagnetic steel sheet is subjected to a predetermined push-back cut at a portion where the core is to be formed, and at the same time, a portion forming an outer contour of the stator core is punched out.

3. The method for manufacturing a stator core according to claim 1 or 2, wherein: The core portion formed in the second step includes a closed-shaped portion that covers an opening of the slot facing the inner periphery of the stator core.

4. The method for manufacturing a stator core according to claim 3, wherein: The planar projection outer shape of the core portion itself formed in the second step is smaller than the planar projection outer shape of the slot.

5. The method for manufacturing a stator core according to claim 4, wherein: The core portion formed in the second step has a void formed in its own planar projection shape.

6. The method for manufacturing a stator core according to claim 1, wherein: The component formed in the fourth step is a stator inner peripheral cover that covers the inner peripheral surface of the stator core and constitutes a cooling medium flow path of the rotating electrical machine having the stator core.

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