Laminated core, rotary electric machine, pressurizing jig, and method for manufacturing laminated core

Abstract

This laminated core (1) comprises a plurality of laminated electromagnetic steel sheets (10), and an adhesion part (41) that is provided between the electromagnetic steel sheets (10) adjacent to each other in the lamination direction and bonds the electromagnetic steel sheets (10) to each other. The adhesion part (41) has a first adhesion section (41A) provided in a first region (11) of the electromagnetic steel sheet (10), and a second adhesion section (41B) provided in a second region (12) different from the first region (11). The compression stress remaining in the first region (11) provided with the first adhesion section (41A) is greater than the compression stress remaining in the second region (12) provided with the second adhesion section (41B).

Description

Laminated core, rotating electric machine, pressing jig, and method for manufacturing laminated core

[0001] The present invention relates to a laminated core, a rotating electrical machine, a pressing jig, and a method for manufacturing a laminated core. This application claims priority to Japanese Patent Application No. 2024-063560, filed on April 10, 2024, the contents of which are incorporated herein by reference.

[0002] As the electrification of automobiles progresses, further improvements in motor efficiency are desired to extend driving range. As one means of achieving higher efficiency, methods of reducing the thickness of the electromagnetic steel sheets used in cores are being considered. As electromagnetic steel sheets become thinner, it becomes difficult to secure the laminated sheets by caulking, and so laminated sheet securing methods using adhesive members are increasingly being adopted. For example, Patent Document 1 discloses a technique for bonding adjacent electromagnetic steel sheets in the lamination direction with adhesive joints.

[0003] International Publication No. 2020 / 129928

[0004] When adhesively fixing magnetic steel sheets, compressive stress is applied to the magnetic steel sheets due to solidification and shrinkage of the adhesive, which can degrade the magnetic properties of the magnetic steel sheets, such as iron loss. Therefore, if the effect of compressive stress due to adhesion can be reduced, the deterioration of motor properties can be suppressed accordingly. Since the main purpose of adhesion is to fix the laminated magnetic steel sheets, it is not necessary to bond the entire surface of the magnetic steel sheets as long as the required overall adhesive strength (fixing force) is obtained. Therefore, as long as the laminated state can be maintained, it is thought that the effect of compressive stress due to adhesion on motor properties can be suppressed by selectively adhesively fixing areas of the magnetic steel sheet surface that have little effect on motor properties.

[0005] On the other hand, during operation of a rotating electric machine such as a motor, each electromagnetic steel sheet constituting a core such as a stator of the rotating electric machine has, in a plan view, a region (second region) through which magnetic flux mainly flows and a region (first region) through which magnetic flux does not flow as much. In other words, since magnetic flux does not flow in the first region as much as in the second region, the impact of solidification shrinkage of the adhesive on the characteristics of the rotating electric machine is thought to be less than that of the second region. Therefore, it was thought that by increasing the fixing force by bonding the first region relatively strongly and compensating for this insufficiency by bonding the second region relatively weakly, it would be possible to obtain the required fixing force overall while suppressing deterioration of the rotating electric machine characteristics due to solidification shrinkage of the adhesive.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a laminated core, a rotating electric machine, a pressing jig, and a method for manufacturing a laminated core that ensures the necessary fixing force while suppressing deterioration of magnetic properties due to adhesion.

[0007] <1> A laminated core according to one embodiment of the present disclosure includes a plurality of stacked electromagnetic steel sheets and adhesive portions provided between adjacent electromagnetic steel sheets in the stacking direction and bonding the electromagnetic steel sheets together, the adhesive portions having a first adhesive portion provided in a first region of the electromagnetic steel sheets and a second adhesive portion provided in a second region different from the first region, and a compressive stress remaining in the first region where the first adhesive portion is provided is greater than a compressive stress remaining in the second region where the second adhesive portion is provided. <2> In the laminated core described in <1> above, the adhesive strength of the first adhesive portion may be greater than the adhesive strength of the second adhesive portion. <3> In the laminated core described in <1> or <2> above, the laminated core may be a stator core, and the first adhesive portion may be annularly provided on the outer periphery of a core back portion of the stator core. <4> In the laminated core described in any one of <1> to <3> above, the first adhesive portion may be located at a position between 0% and 16% of the radius of the electromagnetic steel sheets from the outer periphery of the electromagnetic steel sheets. <5> In the laminated core described in any one of <1> to <4> above, the first adhesive portion may have a bonding area ratio of the electromagnetic steel sheets between 9% and 60%. <6> A rotating electric machine according to an embodiment of the present disclosure includes a stator or rotor core that is the laminated core described in any one of <1> to <5> above. <7> A pressing jig according to an embodiment of the present disclosure is a pressing jig used in manufacturing a laminated core having first adhesive portions and second adhesive portions, the pressing jig including a pressing surface that presses the first adhesive portions and the second adhesive portions, wherein the first pressing portion corresponding to the first adhesive portion protrudes more than the second pressing portion corresponding to the second adhesive portion. <8> A manufacturing method of a laminated core according to one embodiment of the present disclosure is a manufacturing method of a laminated core described in any one of <1> to <5> above, and includes: a specifying step of specifying an area on an electromagnetic steel sheet constituting the laminated core in which the contribution to the magnetic properties is relatively small when a first adhesive portion is provided, based on the results of an analysis of the effect on the magnetic properties of the laminated core; and a determining step of determining a position where the first adhesive portion is to be provided, which is at least a part of the area on the electromagnetic steel sheet specified in the specifying step.<9> The method for manufacturing a laminated core according to the above item <8> may further include a manufacturing step of manufacturing the laminated core according to the determination made in the determining step.

[0008] According to the present disclosure, it is possible to provide a laminated core, a rotating electric machine, a pressing jig, and a method for manufacturing a laminated core, which ensure the necessary fixing force while suppressing deterioration of magnetic properties due to adhesion.

[0009] Fig. 1 is a cross-sectional view showing a laminated core according to an embodiment of the present disclosure; Fig. 2 is a cross-sectional view showing an example of use of a pressing jig according to an embodiment of the present disclosure; Fig. 3 is a flowchart showing a method for manufacturing a laminated core according to an embodiment of the present disclosure; Fig. 4 is a view showing an iron loss distribution determined by electromagnetic field analysis; Fig. 5 is a view showing a correspondence relationship between iron loss distribution and first adhesive portion 41A1; Fig. 6 is a view showing a correspondence relationship between iron loss distribution and first adhesive portion 41A2; Fig. 7 is a view showing a correspondence relationship between iron loss distribution and first adhesive portion 41A3; Fig. 8 is a view showing a correspondence relationship between iron loss distribution and first adhesive portion 41A4; Fig. 9 is a view showing a correspondence relationship between iron loss distribution and first adhesive portion 41A5.

[0010] A laminated core, a pressing jig, and a method for manufacturing a laminated core according to an embodiment of the present disclosure will be described below with reference to the drawings. The laminated core according to the present disclosure may be used in, for example, a rotating electric machine including a rotor and a stator, such as an electric motor (motor) or a generator. The electric motor may be, for example, an AC electric motor, more specifically, a synchronous electric motor, or even more specifically, a permanent magnet field electric motor such as an interior permanent magnet type. This type of electric motor is suitable for use in, for example, electric vehicles.

[0011] 1 is a cross-sectional view showing a laminated core 1 according to this embodiment. The lamination direction of the laminated core 1 is called the axial direction (direction of the central axis O), the radial direction of the laminated core 1 (direction perpendicular to the central axis O of the laminated core 1) is called the radial direction, and the circumferential direction of the laminated core 1 (direction going around the central axis O of the laminated core 1) is called the circumferential direction.

[0012] 1 , the laminated core 1 is, for example, a stator core 21. The stator core 21 includes an annular core back portion 22 and a plurality of teeth portions 23.

[0013] The core back portion 22 is formed in an annular shape in a plan view when the stator core 21 is viewed in the axial direction. The multiple teeth 23 protrude radially inward from the core back portion 22 (toward the central axis O of the core back portion 22 along the radial direction). The multiple teeth 23 are arranged at equal intervals in the circumferential direction. In this embodiment, 48 teeth 23 are provided at central angle intervals of 7.5 degrees around the central axis O. The multiple teeth 23 are formed to have the same shape and size as each other. A winding (not shown) is wound around each tooth 23 to form a stator. The winding may be concentrated winding or distributed winding.

[0014] The laminated core 1 may be a rotor core 31 constituting a rotor 30. The rotor 30 may include a rotor core 31 disposed, for example, radially inside the stator core 21, a plurality of permanent magnets 32 attached to the rotor core 31, and a rotating shaft 60 fixed to the rotor core 31. The rotor core 31 may be formed in an annular (ring-shaped) shape and disposed coaxially with the stator core 21. Furthermore, in the rotor core 31, multiple sets of permanent magnets 32, such as a pair of permanent magnets 32, may form one magnetic pole. The multiple sets of permanent magnets 32 may be disposed at equal intervals in the circumferential direction. When the laminated core 1 is used in a rotating electric machine 200 such as a motor, the rotor 30 may be an inner rotor type disposed within the stator. Alternatively, the rotor 30 may be an outer rotor type disposed outside the stator. The number of poles, slots, and phases of the motor core may be changed as appropriate.

[0015] The laminated core 1 is formed by stacking multiple electromagnetic steel sheets 10, each adhered and fixed with an adhesive. The thickness of each electromagnetic steel sheet 10 forming the laminated core 1 may be determined appropriately taking into consideration the magnetic property improvement effect, such as the iron loss improvement effect, manufacturing costs, and press punching workability. The electromagnetic steel sheets 10 are formed, for example, by punching an electromagnetic steel sheet serving as a base material. In this embodiment, non-oriented electromagnetic steel sheets (e.g., JIS C 2552:2014, etc.) are used as the electromagnetic steel sheets 10, but oriented electromagnetic steel sheets (e.g., JIS C 2553:2019, etc.) may also be used. The chemical composition of the electromagnetic steel sheets 10 is not particularly limited. In order to improve the workability of the electromagnetic steel sheets and the magnetic properties, such as iron loss, of the laminated core, an insulating coating is provided on both sides of the electromagnetic steel sheets 10. The thickness of the insulating coating (thickness per side of the electromagnetic steel sheets 10) is determined appropriately taking into consideration the insulation performance and space factor of the laminated electromagnetic steel sheets 10.

[0016] In addition, types of adhesives used to bond and fix the electromagnetic steel sheet 10 include, for example, thermosetting adhesives using polymerization bonding, acrylic adhesives that cure at room temperature, anaerobic adhesives, instant adhesives, and elastomer-containing acrylic adhesives.

[0017] Here, the electromagnetic steel sheet 10 has a first region 11 and a second region 12 (see FIG. 1 ). The first region 11 and the second region 12 are determined based on the distribution of magnetic flux density when the rotating electric machine 200 is operated (driven) under one or more representative operating conditions (hereinafter, referred to as "excitation"). The first region 11 is a region where less magnetic flux flows than the second region 12 during excitation (a region with higher magnetic reluctance and lower magnetic flux density), and is at least a portion of that region, such as a region with lower magnetic flux density. The first region 11 may include at least a portion of a region in the core that is not excited or is difficult to excite due to the structure or winding conditions of the rotating electric machine 200. The second region 12 is a region where a relatively large amount of magnetic flux flows during excitation (a region with lower magnetic reluctance and higher magnetic flux density), and is not the first region 11.

[0018] For example, the first region 11 may be defined from a region having a magnetic flux density equal to or lower than a predetermined threshold, and the other region may be defined as the second region 12. The electromagnetic steel sheet 10 may further have a third region, and the region other than the first region 11 defined as described above may be divided into the second region 12 and a third region, such as a region where no adhesive portion is provided, based on the distribution of magnetic flux density, for example.

[0019] In other words, the first region 11 is a region that contributes less to magnetic characteristic values ​​such as iron loss (iron loss value per unit volume or unit weight) than the second region 12. The contribution to the magnetic characteristic values ​​can be determined, for example, by modeling the laminated core 1 on software and simulating the distribution of magnetic characteristics. Note that the first region 11 may be selected based on the empirical knowledge of an expert or the like.

[0020] As already explained, in the laminated core 1, adjacent electromagnetic steel sheets 10 are bonded and fixed together with an adhesive. That is, the laminated core 1 has adhesive portions 41 provided between adjacent electromagnetic steel sheets 10 in the stacking direction and bonding the electromagnetic steel sheets 10 together. The adhesive portions 41 are formed after the adhesive as described above has solidified (cured). The adhesive portions 41 may be provided over the entire surfaces of the electromagnetic steel sheets 10, or may be provided partially on the surfaces of the electromagnetic steel sheets 10.

[0021] The adhesive portion 41 will be described in detail below. As shown in Fig. 1 , the adhesive portion 41 has a first adhesive portion 41A provided in the first region 11 (described above) of the electromagnetic steel sheet 10, and a second adhesive portion 41B provided in a second region 12 (a region other than the first adhesive portion 41A in Fig. 1 ) that is a region different from the first adhesive portion 41A. In other words, the region where the first adhesive portion 41A is provided is the first region 11, and the region where the second adhesive portion 41B is provided is the second region 12.

[0022] In the laminated core 1, the compressive stress remaining in the first region 11 where the first adhesive portion 41A is provided is higher than the compressive stress remaining in the second region 12 where the second adhesive portion 41B is provided. In other words, a compressive stress distribution corresponding to the first region 11 and the second region 12 is generated in the electromagnetic steel sheet 10. This compressive stress distribution remaining in the electromagnetic steel sheet 10 may be achieved by changing the type of adhesive used to form the first adhesive portion 41A and the second adhesive portion 41B. In other words, the first adhesive 41Ag forming the first adhesive portion 41A and the second adhesive 41Bg forming the second adhesive portion 41B may be different adhesives. Alternatively, the same type of adhesive may be used by using an adhesive that exhibits adhesive strength according to the magnitude of pressure applied during bonding. In other words, the first adhesive 41Ag forming the first adhesive portion 41A and the second adhesive 41Bg forming the second adhesive portion 41B may be the same adhesive. In this case, the above-mentioned compressive stress distribution may be formed by changing the pressure during bonding, for example, by making the pressure applied to the first region 11 greater than the pressure applied to the second region 12 during bonding.

[0023] The compressive stress distribution or the difference in compressive stress between regions in the electrical steel sheet 10 can be measured, for example, by X-ray diffraction (XRD). Details of X-ray diffraction are described in the following literature: X-Ray Stress Measurement Standard (2002 Edition) Iron and Steel Edition (JSMS SD-5-02:2002), published by the Japan Society for Materials Science. In the laminated core 1, if the compressive residual stress is greater than or equal to a predetermined threshold value (e.g., 3 MPa or 5 MPa) compared to other regions, the region (first adhesive portion 41A) can be identified as having a high adhesive strength. This threshold value may be set to a value greater than the range of variation in measured values ​​due to measurement error or the like.

[0024] The region with high adhesive strength (first adhesive portion 41A) is pressurized by the convex portion of the pressing jig 100 described below. This may result in a depression compared to other regions. That is, in the region with high adhesive strength, the first adhesive portion 41A may be thinner than the second adhesive portion 41B due to the strong pressure. Therefore, a method for confirming and identifying the region with high adhesive strength (first adhesive portion 41A) can be considered by observing the surface or cross section of the laminated core 1. Furthermore, this method also makes it possible to confirm and identify the region (first adhesive portion 41A) where adhesive strength is changed by partial pressure application.

[0025] For example, a possible method is to confirm that the adhesive strength of the first adhesive portion 41A is greater than the adhesive strength of the second adhesive portion 41B using a JIS adhesive strength test, such as a peel strength test. Alternatively, the adhesive strength of the first adhesive portion 41A and the second adhesive portion 41B may be measured using a shear strength measurement method. For the shear strength measurement method, an Autograph AGS-10kNX (Shimadzu Corporation) is used as a tensile tester. The test conditions are as follows: tensile mode: shear tensile test, tensile temperature: 25°C, tensile speed: 50 mm / min. For shear strength measurement, the tensile test is performed until the test piece (the first adhesive portion 41A or the second adhesive portion 41B) breaks. If multiple test pieces can be obtained, the average of the maximum strengths measured until breakage for each test piece is taken as the shear adhesive strength. The obtained shear adhesive strength value is then divided by the adhesive area to determine the room temperature adhesive strength. This also makes it possible to confirm that the adhesive strength of the first adhesive portion 41A is greater than the adhesive strength of the second adhesive portion 41B.

[0026] The first adhesive portion 41A and the second adhesive portion 41B may each include one solidified portion of adhesive, or may include multiple solidified portions of adhesive arranged regularly or irregularly and spaced apart from each other.

[0027] When adhesively fixing the electromagnetic steel sheets 10, compressive stress is applied to the electromagnetic steel sheets 10 as the adhesive solidifies and shrinks, which may result in degradation of the magnetic properties of the electromagnetic steel sheets 10. However, in the laminated core 1 according to this embodiment, the adhesive strength (adhesive force) in the region (first region 11) that has little effect on magnetic properties (such as core loss and other properties of the rotating electric machine 200, such as motor properties) is increased compared to the region that has a greater effect on the magnetic properties, while the adhesive strength in the region (second region 12) that has a greater effect on the magnetic properties is weakened, thereby reducing the compressive stress applied to that region. This reduces the compressive stress applied to the electromagnetic steel sheets 10 due to solidification and shrinkage of the adhesive in the second region 12, while allowing the first region 11 to be strongly adhesively fixed. Therefore, the laminated core 1 as a whole can ensure the required adhesive strength while suppressing degradation of the magnetic properties due to adhesion.

[0028] Next, specific locations of the first adhesive portion 41A and the second adhesive portion 41B will be described. The magnetic flux density distribution during excitation is lower on the outer circumferential side of the core back portion 22 of the stator core 21 than on the inner circumferential side or in the teeth portion 23. The core back portion 22 also includes a region that is difficult to excite (the dark semicircular region in FIG. 4 ). Therefore, the first region 11 may be located on the outer circumferential edge 16 side of the annular core back portion 22. That is, the first region 11 may be provided in a ring shape, for example, at a position between the outer circumferential edge 16 and a position a predetermined distance inward in the radial direction. In this case, the first adhesive portion 41A may be provided along the outer circumferential edge 16 of the core back portion 22 in the form of a strip of solidified adhesive or in the form of multiple solidified adhesive lines. A region without the first adhesive portion 41A (a non-bonded region) may be present between the first adhesive portion 41A and the outer circumferential edge 16 of the core back portion 22. The width of the strip-shaped first adhesive portion may be constant or may vary partially.

[0029] On the other hand, the second region 12 is at least a part of a region other than the first region 11, and therefore the second adhesive portion 41B is provided in a portion other than the first adhesive portion 41A in the core back portion 22 of the stator core 21. For example, when the first adhesive portion 41A is provided in an annular shape on the outer circumferential side of the core back portion 22 as described above, the second adhesive portion 41B is disposed radially inward of the first adhesive portion 41A.

[0030] 1 , each electromagnetic steel sheet 10 is divided into two regions, a first region 11 and a second region 12, and an adhesive portion 41 is provided on the entire surface of each electromagnetic steel sheet 10. The first adhesive portion 41A and the second adhesive portion 41B are formed by a single solidified portion. Furthermore, one type of adhesive is applied to at least a portion between the two electromagnetic steel sheets 10, and then solidified (hardened) while applying different pressures in the stacking direction to the regions corresponding to the first region 11 and the second region 12 of the electromagnetic steel sheet 10, thereby providing the first adhesive portion 41A and the second adhesive portion 41B on each electromagnetic steel sheet 10.

[0031] However, the present invention is not limited to this embodiment. The adhesives applied to the first region 11 and the second region 12 may be different types of adhesive that have different adhesive strengths after solidification. Furthermore, the adhesive portion 41 does not have to be provided over the entire surface between the electromagnetic steel sheets 10. Specifically, at least one of the first adhesive portion 41A and the second adhesive portion 41B may be composed of multiple solidified portions that are spaced apart from each other. Alternatively, the electromagnetic steel sheet 10 may further have a third region that has no adhesive portion. A combination of these may also be used.

[0032] In this way, by providing the first adhesive portion 41A on the outer periphery of the core back portion 22 of the stator core 21, which has little effect on magnetic properties such as iron loss, the first adhesive portion 41A ensures the necessary adhesive strength in the first region 11, which has little effect on magnetic properties, while the second adhesive portion 41B reduces the compressive stress in the second region 12, which has a large effect on magnetic properties, thereby further suppressing deterioration of the magnetic properties overall.

[0033] In a plan view of the electromagnetic steel sheet 10 seen from the stacking direction, the first adhesive portion 41A is preferably provided at a distance of 0% to 16% of the radius of the electromagnetic steel sheet 10 from the outer peripheral edge 16 of the electromagnetic steel sheet 10. This allows the first adhesive portion 41A to be positioned on the outer peripheral edge 16 side of the electromagnetic steel sheet 10, thereby further suppressing deterioration of magnetic properties such as iron loss deterioration. The first adhesive portion 41A is more preferably provided at a distance of 0% to 6% of the radius of the electromagnetic steel sheet 10 from the outer peripheral edge 16 of the electromagnetic steel sheet 10, and even more preferably at a distance of 0% to 3%.

[0034] In a plan view of the electromagnetic steel sheet 10 seen from the stacking direction, the bonding area ratio of the electromagnetic steel sheet 10 by the first adhesive portion 41A is preferably 9% to 60% inclusive, more preferably 10% to 60% inclusive, to ensure an appropriate fixing force. If the bonding area ratio of the electromagnetic steel sheet 10 by the first adhesive portion 41A is too large, the magnetic properties will deteriorate significantly, so it is preferably 20% or less. In other words, the bonding area ratio is preferably 9% to 20% inclusive, or 10% to 20% inclusive. The bonding area ratio of the electromagnetic steel sheet 10 by the first adhesive portion 41A is the ratio of the area of ​​the region where the first adhesive portion 41A is provided to the area of ​​the electromagnetic steel sheet 10. The region where the first adhesive portion 41A is provided is the region of the electromagnetic steel sheet 10 where the hardened adhesive is provided without being separated. The area of ​​the region where the first adhesive portion 41A is provided can be determined, for example, by photographing the electromagnetic steel sheet 10 after peeling and analyzing the image results.

[0035] The electromagnetic steel sheets 10 are manufactured so that all of the adhesive portions 41 provided between the adjacent electromagnetic steel sheets 10 are positioned at approximately the same positions in a plan view.

[0036] The above description has been given taking the case where the laminated core 1 is the stator core 21 as an example, but the laminated core 1 may also be the rotor core 31. The first region 11 and the second region 12 of the electromagnetic steel sheets 10 that make up the rotor core 31 are determined based on factors such as the distribution of magnetic flux density in the electromagnetic steel sheets 10 when excited. For example, the first region 11 may be provided on the rotating shaft 60 side, or may be provided in a circular ring shape.

[0037] [Rotating Electric Machine] The rotating electric machine 200 includes a stator core 21 or a rotor core which is the above-described laminated core 1. The rotating electric machine 200 according to this embodiment includes a stator core 21 or a rotor core which is the above-described laminated core 1, and therefore can provide a rotating electric machine 200 with improved performance by further suppressing deterioration of magnetic characteristics such as iron loss deterioration while ensuring the necessary adhesive strength.

[0038] [Pressing Jig] The pressing jig 100 used in manufacturing the laminated core 1 according to the above-described embodiment will be described. Fig. 2 is a schematic diagram showing an example of use of the pressing jig 100. The pressing jig 100 is used when pressure needs to be applied for bonding, for example, when an adhesive coating is mainly provided on the electromagnetic steel sheets 10.

[0039] The pressing jig 100 is a jig used to press a stack of multiple electromagnetic steel sheets 10 constituting the laminated core 1, at least some of which are stacked with adhesive sandwiched between them (hereinafter referred to as core part P), for adhesive fixation during the manufacture of the laminated core 1. As shown in Fig. 2, the pressing jig 100 includes a first member 110 having an uneven pressing surface 111 that presses the core part P while contacting it. The core part P is bonded by applying pressure to it via the first member 110 using a pressing unit 101 of a pressing device. The core part P may be heated to a predetermined temperature before pressure is applied.

[0040] More specifically, the pressing surface 111 of the first member 110 has a surface (region) corresponding to the region where the first adhesive portion 41A is formed in the first region 11 of the electromagnetic steel sheet 10 protruding further than a surface (region) corresponding to the region where the second adhesive portion 41B is formed in the stacking direction of the laminated core 1. In other words, the surface (region) corresponding to the first adhesive portion 41A has a convex shape in the stacking direction of the laminated core 1, and the surface (region) corresponding to the second adhesive portion 41B has a concave shape in the stacking direction of the laminated core 1. In this way, the pressing surface 111 has a first pressing portion 111A (convex portion) configured to press relatively strongly against the region corresponding to the first adhesive portion 41A, and a second pressing portion 111B (concave portion) configured to press relatively weakly against the region corresponding to the second adhesive portion 41B.

[0041] In other words, the pressing jig 100 has an uneven pressing surface 111 so that the pressure applied to the desired area of ​​the core portion P is higher than that applied to other areas during bonding. The uneven shape of the pressing surface 111 in a plan view of the laminated core 1 from the stacking direction is designed according to the shape of the area to be actively pressed. This causes the area corresponding to the convex portion (first pressing portion 111A) to receive a higher pressure during pressing than the area corresponding to the concave portion (second pressing portion 111B). Therefore, if the adhesive used to bond and fix the laminated core 1 is of a type that exhibits adhesive strength corresponding to the magnitude of pressure applied during bonding, the first adhesive portion 41A and the second adhesive portion 41B can be formed by applying pressure to the core portion P in one go.

[0042] 2, the pressing jig 100 (first member 110) is a plate-like member having projections and recesses formed thereon, such as a mold having projections and recesses formed in the thickness direction of a metal plate having a predetermined thickness. When pressed by the pressing unit 101, the first pressing unit 111A of the first member 110 presses the first region 11 (first adhesive portion 41A) provided on the outer periphery of the core back portion 22, and the second pressing unit 111B presses the second region 12 (second adhesive portion 41B) other than the first region 11.

[0043] The pressing surface 111 also includes a tapered portion 112 that connects the first pressing portion 111A and the second pressing portion 111B. That is, the first pressing portion 111A and the second pressing portion 111B are smoothly connected, and are formed so that the pressure applied thereto changes gradually. As a configuration in which the pressure applied thereto changes gradually, for example, the tapered portion 112 may be gradually inclined at a constant rate, or may change in a quadratic curve.

[0044] 2, a first member 110 is disposed above the core portion P with its pressing surface 111 facing downward. In addition, the core portion P is supported from below by being disposed on the upper surface of a second member 120 fixedly disposed below the core portion P, and the first member 110 is pressed in the direction of arrow F (downward in the stacking direction) by a pressing unit 101 of a pressing device, thereby applying pressure to the core portion P and adhesively fixing it.

[0045] However, the present invention is not limited to the above-described embodiment. For example, the first member 110 may be disposed below and the second member 120 may be disposed above. Furthermore, in addition to the first member 110, the support surface of the core portion P of the second member 120 may also be formed with concaves and convexes that match the concaves and convexes of the pressing surface 111 of the first member 110. Furthermore, the first pressing portion 111A and the second pressing portion 111B of the first member 110 do not have to include the tapered portion 112, and may be connected by, for example, a single staircase-like step portion.

[0046] 2 is a schematic representation of the shape of the pressing jig 100 for ease of understanding, and the dimensions of the actual pressing jig 100 may differ. For example, in the view indicated by the arrow in FIG. 2 (side view of the laminated core 1), a difference H (μm) in the unevenness of the pressing surface 111 is provided. The difference H may be determined by determining the compressive stress to be applied to the electromagnetic steel sheets 10, calculating, through experiments or calculations, the bonding pressure that will provide a bonding strength corresponding to the determined compressive stress, and then calculating the difference H that will provide this bonding pressure.

[0047] According to the above-described pressing jig 100, the unevenness formed on the pressing surface 111 makes it possible to create a pressure distribution on the surface of the electromagnetic steel sheet 10 with a single application of pressure. Therefore, when bonding and fixing, a higher pressure can be applied to the area of ​​the electromagnetic steel sheet 10 where the first adhesive portion 41A is to be formed than to the area where the second adhesive portion 41B is to be formed with a single application of pressure. Therefore, the first adhesive portion 41A and the second adhesive portion 41B can be formed efficiently, thereby reducing the manufacturing cost of the laminated core 1.

[0048] [Manufacturing Method of Laminated Core] A manufacturing method S of the laminated core 1 according to the above-described embodiment will be described. As shown in FIG. 3, the manufacturing method S of the laminated core 1 according to the above-described embodiment includes a specifying step S1 and a determining step S2.

[0049] In the identification step S1, based on the results of an analysis of the effects on the magnetic properties of the laminated core 1, such as iron loss, an area is identified in which the contribution to the magnetic properties is relatively small when the first adhesive portion 41A is provided on the electromagnetic steel plate 10 constituting the laminated core 1.

[0050] In the determining step S2, a first region 11 is determined, which is at least a part of the region on the electromagnetic steel sheet 10 identified in the identifying step S1, and in which the first adhesive portion 41A is to be provided. In addition, a second region 12 is determined for the region of the electromagnetic steel sheet 10 other than the determined first region 11. The second region 12 may be at least a part of the region of the electromagnetic steel sheet 10 other than the first region 11, or it may be the entire region. In addition, in the determining step S2, a third region may be determined after the first region 11 is determined. The third region is determined to be at least a part other than the first region 11 and the second region 12. The third region may be determined together with the second region 12, or may be determined after the second region 12 is determined.

[0051] The manufacturing method S of the laminated core 1 includes a manufacturing step S3 of manufacturing the laminated core 1 in accordance with the determination made in the determination step S2.

[0052] [Example] Figure 4 shows the results of determining which areas have small iron loss when iron loss distribution is obtained by electromagnetic field analysis. In Figure 4, darker areas are areas with small iron loss values, and lighter areas are areas with large iron loss values. Figures 5 to 9 show the correspondence between iron loss distribution and first adhesive portions 41A (first adhesive portions 41A1-41A5). Note that grayscale charts are provided at the bottom of Figures 4 to 9 as a legend for the shading.

[0053] In the first example shown in Fig. 5, the region with the smallest iron loss value was selected as the first region 11, and the first adhesive portion 41A (first adhesive portion 41A1) was provided therein. That is, in the first example, the region with the smallest iron loss value and the first adhesive portion 41A1 are made to substantially coincide with each other. The first adhesive portions 41A1 are arranged in a substantially semicircular shape at multiple locations that contact the outer peripheral edge 16 of the electromagnetic steel sheet 10. The adhesive area ratio of the electromagnetic steel sheet 10 by the first adhesive portions 41A1 is approximately 9%.

[0054] In the second example shown in Fig. 6, a region with a low iron loss value adjacent to the region with the lowest iron loss value was selected as the first region 11, and a first adhesive portion 41A (first adhesive portion 41A2) was provided therein. In the second example, the first adhesive portion 41A2 is arranged inside the region with the lowest iron loss value. The first adhesive portion 41A2 has a band shape that extends along the outer peripheral edge 16 of the electromagnetic steel sheet 10 and is in contact with and separates from the outer peripheral edge 16. The adhesive area ratio of the electromagnetic steel sheet 10 by the first adhesive portion 41A2 is approximately 13%.

[0055] In the third embodiment shown in Fig. 7, both the region selected in the first embodiment and the region selected in the second embodiment are selected as the first region 11, and first adhesive portions 41A (first adhesive portions 41A3) are provided. In the third embodiment, the first adhesive portions 41A3 are arranged so as to substantially cover the region with a small iron loss value. The outside of the first adhesive portions 41A3 contacts most of the outer periphery 16 of the electromagnetic steel sheet 10, and the inside has a wavy, undulating shape. The adhesive area ratio of the electromagnetic steel sheet 10 by the first adhesive portions 41A3 is approximately 22%.

[0056] In the fourth example shown in Fig. 8, a range within approximately 3% of the radial extent from the outer circumferential edge 16 of the electromagnetic steel sheet 10 is selected as the first region 11, and the first adhesive portion 41A (first adhesive portion 41A4) is provided therein. In the fourth example, part of the region with the smallest iron loss value is included in the first adhesive portion 41A4. The first adhesive portion 41A4 has a thin annular shape that follows the outer circumferential edge 16 of the electromagnetic steel sheet 10. The adhesive area ratio of the electromagnetic steel sheet 10 by the first adhesive portion 41A4 is approximately 10%.

[0057] In the fifth example shown in Fig. 9, a range within approximately 6% of the radial direction from the outer circumferential edge 16 of the electromagnetic steel sheet 10 is selected as the first region 11, and the first adhesive portion 41A (first adhesive portion 41A5) is provided therein. In the fifth example, the first adhesive portion 41A5 covers most of the region with the smallest iron loss value. The first adhesive portion 41A5 has a ring shape that is thicker than the first adhesive portion 41A4 and is located along the outer circumferential edge 16 of the electromagnetic steel sheet 10. The adhesive area ratio of the electromagnetic steel sheet 10 provided by the first adhesive portion 41A5 is approximately 20%.

[0058] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0059] The shape of the laminated core 1 is not limited to the form shown in the above embodiment. The outer and inner diameters of the laminated core 1, the lamination thickness, and other dimensions can be designed as desired according to the characteristics of the laminated core 1. The number of slots in the stator core 21, the circumferential and radial dimensional ratio of the teeth 23, and the radial dimensional ratio of the teeth 23 to the core back 22 can also be designed as desired according to the characteristics of the laminated core 1. In addition, while the above embodiment has been described using the stator core 21 as an example of the laminated core 1, the laminated core 1 may also be a rotor core, and the present invention is similarly applicable.

[0060] According to the present disclosure, it is possible to provide a laminated core, a rotating electric machine, a pressing jig, and a method for manufacturing a laminated core, which are capable of suppressing deterioration of magnetic properties due to adhesion while ensuring the necessary fixing force, and thus have great industrial applicability.

[0061] REFERENCE SIGNS LIST 1 Laminated core 10 Electromagnetic steel sheet 11 First region 12 Second region 21 Stator core 22 Core back portion 23 Teeth portion 30 Rotor 31 Rotor core 32 Permanent magnet 41 Adhesion portion 41A First adhesion portion 41Ag First adhesive 41B Second adhesion portion 41Bg Second adhesive 100 Pressurizing jig 110 First member 111 Pressing surface 111A First pressing portion 111B Second pressing portion 120 Second member 200 Rotating electric machine S Manufacturing method S1 Identification step S2 Determination step S3 Manufacturing step

Claims

1. Multiple laminated electrical steel sheets, It comprises an adhesive portion provided between adjacent electrical steel sheets in the stacking direction, which bonds the electrical steel sheets together, The aforementioned adhesive portion is A first adhesive portion provided in the first region of the electrical steel sheet, It has a second adhesive portion provided in a second region different from the first region, The first region is at least a part of the region in which less magnetic flux flows than in the second region when excited. The compressive stress remaining in the first region where the first adhesive portion is provided is, A laminated core having a compressive stress greater than the compressive stress remaining in the second region where the second adhesive portion is provided.

2. The laminated core according to claim 1, wherein the adhesive strength of the first adhesive portion is greater than the adhesive strength of the second adhesive portion.

3. The aforementioned stacked core is a stator core, The laminated core according to claim 1, wherein the first adhesive portion is provided in an annular shape on the outer circumference of the core back portion of the stator core.

4. The laminated core according to claim 3, wherein the first adhesive portion is located at a distance of 0% to 16% of the radius of the electrical steel sheet from the outer edge of the electrical steel sheet.

5. The laminated core according to claim 3, wherein the bonding area ratio of the electromagnetic steel sheet by the first bonding portion is 9% or more and 60% or less.

6. The laminated core according to claim 1, wherein the first adhesive forming the first adhesive portion and the second adhesive forming the second adhesive portion are of the same type.

7. The laminated core according to claim 6, wherein the adhesive portion is provided over the entire surface between adjacent electrical steel sheets in the lamination direction.

8. A rotating electric machine comprising a stator core or rotor core which is a laminated core as described in any one of claims 1 to 7.

9. A pressurizing jig used in the manufacture of a laminated core having a first adhesive portion and a second adhesive portion as described in any one of claims 1 to 7, The device comprises a pressing surface that presses against the first adhesive portion and the second adhesive portion, The pressing surface is a pressurizing jig in which the first pressing portion corresponding to the first adhesive portion protrudes more than the second pressing portion corresponding to the second adhesive portion.

10. A method for manufacturing a laminated core according to any one of claims 1 to 7, Based on the results of the analysis of the influence on the magnetic properties of the laminated core, the step of identifying a region in which the contribution to the magnetic properties is relatively small when a first adhesive portion is provided on the electromagnetic steel sheet constituting the laminated core, A method for manufacturing a laminated core, comprising: a determination step of determining a position in which the first adhesive portion is provided, which is at least a part of the region on the electromagnetic steel sheet identified in the specified step.

11. A method for manufacturing a laminated core according to claim 10, further comprising a manufacturing step of manufacturing the laminated core in accordance with the determination in the determination step.