Magnetic body core and method for manufacturing same
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NANYANG TECH UNIV
- Filing Date
- 2026-01-23
- Publication Date
- 2026-07-30
Smart Images
Figure JP2026002293_30072026_PF_FP_ABST
Abstract
Description
Magnetic Core and Method for Manufacturing the Same
[0001] The present disclosure relates to a magnetic core and a method for manufacturing the magnetic core.
[0002] In a conventional motor, in order to reduce eddy current loss, it is common to use a magnetic core formed by laminating electromagnetic steel sheets having a thickness of about 0.35 to 0.5 mm.
[0003] As a new manufacturing technology for magnetic cores, additive manufacturing is known. Additive manufacturing has the advantage of being able to process complex shapes, so it can increase the degree of design freedom and may support the development of next-generation motors. However, an object formed by additive manufacturing is usually a bulk (i.e., a lump having a large thickness), unlike the electromagnetic steel sheets used in conventional motors. This is disadvantageous for achieving low eddy current loss and reduces the efficiency of the motor. Therefore, in order to promote the application of additive manufacturing to the manufacture of motors and the like, it is required to reduce the eddy current loss of the magnetic core formed by additive manufacturing.
[0004] For example, Patent Document 1 discloses a core for a rotating electrical machine that reduces eddy current loss. The core for a rotating electrical machine in Patent Document 1 is composed of a laminate in which a plurality of shaped layers formed by melting and solidifying metal powder are integrally laminated. The laminate has a core material formed following the outer shape of the laminate in a plan view seen from the shaping direction of the shaped layer, and a connecting portion that is formed smaller than the core material in a plan view seen from the shaping direction and integrally connects the core materials to each other with a gap between adjacent core materials.
[0005] It is also known that by complicating the surface shape of the magnetic core, the eddy current path on the surface of the magnetic core is increased, thereby reducing the eddy current loss of the magnetic core.
[0006] Japanese Patent No. 6489559
[0007] For example, it is difficult to construct a 3D model of a magnetic core with a complex structure like that described in Patent Document 1. Furthermore, when applying magnetic cores with such structures to actual motors, the design becomes extremely complex. In addition, irregular magnetic flux paths along the surface of the magnetic core may degrade the magnetic performance of the motor. Therefore, there is a need for a magnetic core formed by additive manufacturing that has lower eddy current losses than bulk magnetic cores without excessively complicating its structure.
[0008] The object of this disclosure is to provide a magnetic core formed by additive manufacturing that has lower eddy current losses than a bulk magnetic core without excessively complicating the structure. The object of this disclosure is also to provide a method for manufacturing such a magnetic core.
[0009] A method for manufacturing a magnetic core according to one aspect of the present disclosure includes forming a plurality of thin plate portions made of a magnetic material using an additive manufacturing method. The plurality of thin plate portions are arranged periodically with a predetermined gap between them so that the surfaces of adjacent thin plate portions face each other. Forming the plurality of thin plate portions includes (1) and (2) below: (1) Forming a plurality of magnetic material segments by arranging magnetic material along a plurality of scan line sections of the additive manufacturing method that are arranged at predetermined intervals from each other; (2) Forming the plurality of thin plate portions by repeatedly forming the plurality of magnetic material segments by stacking another magnetic material segment on top of the magnetic material segment.
[0010] A magnetic core according to another aspect of the present disclosure has a plurality of thin plate portions made of magnetic material. The plurality of thin plate portions are arranged periodically with a predetermined gap between them so that the surfaces of adjacent thin plate portions face each other. The plurality of thin plate portions are formed using additive manufacturing as follows: That is, the plurality of thin plate portions are formed by repeatedly stacking magnetic segments on top of magnetic segments by arranging magnetic material along a plurality of scan line sections of the additive manufacturing method that are arranged at predetermined intervals from each other.
[0011] According to a method for manufacturing a magnetic core according to one aspect of this disclosure, it is possible to provide a magnetic core having lower eddy current losses than a bulk magnetic core without excessively complicating the structure.
[0012] Furthermore, a magnetic core according to another aspect of this disclosure has lower eddy current losses than a bulk magnetic core.
[0013] This is a perspective view showing an example configuration of the magnetic core 100 according to the first embodiment. This is a schematic diagram showing an additive manufacturing apparatus 200 for forming the magnetic core 100 of Figure 1. This is a diagram for explaining the formation of the magnetic core according to the first comparative example. This is a diagram for explaining the formation of the magnetic core according to the second comparative example. This is a diagram for explaining the formation of the magnetic core 100 of Figure 1. This is a diagram showing an exemplary 3D model 100M for forming the magnetic core 100 of Figure 1. This is a diagram showing the first step for forming the magnetic core 100A according to an example of the first embodiment. This is a diagram showing the second step for forming the magnetic core 100A according to an example of the first embodiment. This is a diagram showing the third step for forming the magnetic core 100A according to an example of the first embodiment. This is a diagram showing the fourth step for forming the magnetic core 100A according to an example of the first embodiment. This is a diagram showing the scan line layout 221 for forming the magnetic core 100A of Figures 7A to 7D. This is a diagram showing another scan line layout 222 for forming the magnetic core 100A of Figures 7A to 7D. Figure 7D is a vertical cross-sectional view showing an example of the configuration of a motor 301 equipped with the outer core 308. Figure 7D is a horizontal cross-sectional view showing an example of the configuration of a motor 301 equipped with the outer core 308. This figure shows the first step of forming the magnetic core 100B according to the second embodiment. This figure shows the second step of forming the magnetic core 100B according to the second embodiment. This figure shows the third step of forming the magnetic core 100B according to the second embodiment. This figure shows the fourth step of forming the magnetic core 100B according to the second embodiment. This figure shows the fifth step of forming the magnetic core 100B according to the second embodiment. This figure shows the first step of forming the magnetic core 100C according to a modified example of the second embodiment. This figure shows the second step of forming the magnetic core 100C according to a modified example of the second embodiment. This figure shows the third step of forming the magnetic core 100C according to a modified example of the second embodiment. This figure shows the fourth step of forming the magnetic core 100C according to a modified example of the second embodiment. This is a perspective view showing the configuration of an outer core 308D equipped with a magnetic core 100D according to an example of the second embodiment. This diagram shows the first step in forming the magnetic core 100E according to the third embodiment. This diagram shows the second step in forming the magnetic core 100E according to the third embodiment.This is a diagram showing the third step in forming the magnetic core 100E according to the third embodiment. This is a diagram showing the fourth step in forming the magnetic core 100E according to the third embodiment. This is a diagram showing the fifth step in forming the magnetic core 100E according to the third embodiment. This is a diagram showing the sixth step in forming the magnetic core 100E according to the third embodiment. This is a perspective view showing the configuration of the outer core 308F according to an embodiment of the third embodiment.
[0014] The embodiments of this disclosure will be described in detail below with reference to the drawings. However, the configurations described below are merely examples of this disclosure, and this disclosure is not limited to the embodiments described below. Various modifications are possible in other embodiments as long as they do not depart from the technical idea related to this disclosure, depending on the design, etc.
[0015] [First Embodiment] [Configuration of Magnetic Core] Figure 1 is a perspective view showing an example of the configuration of a magnetic core 100 according to the first embodiment. The magnetic core 100 comprises a plurality of thin plate portions 101 made of magnetic material. The plurality of thin plate portions 101 are arranged periodically with a predetermined gap 102 such that the surfaces of adjacent thin plate portions 101 face each other. The plurality of thin plate portions 101 are formed using an additive manufacturing method, as will be described later.
[0016] According to Faraday's law of induction, when a changing magnetic field is applied to a conductor, eddy currents are induced within the conductor in a direction that counteracts the magnetic field. According to the Joule-Lenz law, when eddy currents flow through a conductor, the energy of the current is dissipated as heat. This power loss is called eddy current loss and reduces the efficiency of AC machinery. Therefore, reducing eddy current loss and improving motor efficiency is one of the most important concerns in motor design and manufacturing.
[0017] Under conditions of uniform material, uniform magnetic field, and no skin effect, the power loss due to eddy currents per unit mass of a thin sheet or wire is calculated by the following formula:
[0018]
[0019] Here, we will use the following symbols.
[0020] P: Power loss per unit mass (W / kg) B ｐ : Peak magnetic field (T) d: Sheet thickness (m) f: Frequency (Hz) k: Constant (equal to 1 for thin sheets) ρ: Resistivity of material (Ωm) D: Density of material (kg / m³) ３ ) π: Pi
[0021] Eddy current losses can be reduced by decreasing the material thickness d.
[0022] According to the magnetic core 100 of this embodiment, by providing a plurality of thin plate portions 101 that are periodically arranged with a predetermined gap 102, it is possible to achieve lower eddy current losses than bulk magnetic cores without excessively complicating the structure.
[0023] [Method for Manufacturing a Magnetic Core] Figure 2 is a schematic diagram showing an additive manufacturing apparatus 200 for forming the magnetic core 100 shown in Figure 1. The additive manufacturing apparatus 200 creates an object using a predetermined additive manufacturing method, for example, laser powder bed fusion (LPBF). The additive manufacturing apparatus 200 comprises a housing 201, a laser light source 202, and a drive device 203. The housing 201 is filled with metal powder 204 of a magnetic material from the bottom up to a predetermined height. The laser light source 202 irradiates the metal powder 204 with laser light 205, causing the metal powder 204 to melt and solidify. The drive device 203 moves the laser light source 202 in three dimensions.
[0024] The additive manufacturing apparatus 200 forms multiple magnetic material segments 210 on a planar substrate 110 by arranging magnetic material along multiple scan line sections of the additive manufacturing method, that is, by melting and solidifying metal powder 204. In the example shown in Figure 2, the multiple scan line sections extend along the Y-axis and are arranged at predetermined intervals from each other in the X-axis direction. Once one layer of magnetic material segment 210 is formed, metal powder 204 is filled into the magnetic material segment 210 up to a predetermined height. Next, the additive manufacturing apparatus 200 forms the next layer of magnetic material segment 210. The additive manufacturing apparatus 200 repeatedly forms multiple magnetic material segments 210 by stacking another magnetic material segment 210 on top of a magnetic material segment 210, thereby forming multiple thin plate portions 101. In this specification, the Z-axis direction of the additive manufacturing apparatus 200 is referred to as the "manufacturing direction".
[0025] The magnetic core 100 is formed from a predetermined magnetic material, such as an easily moldable compacted magnetic core material or a soft magnetic metal powder. The magnetic core 100 may be formed from a soft magnetic material containing, for example, (a) iron, (b) a combination of iron and silicon, or (c) a combination of iron and cobalt. The magnetic core 100 may contain 93.5 to 99.5% iron and 0.5 to 6.5% silicon as components. The magnetic core 100 may also be Permendur 2V containing 49% iron, 49% cobalt, and 2% vanadium as components.
[0026] Next, referring to Figures 3 to 5, we will explain how to set the parameters for the additive manufacturing method to form a plurality of thin plate portions 101 that are periodically arranged with a predetermined gap 102.
[0027] Figure 3 is a diagram illustrating the formation of a magnetic core according to the first comparative example. The additive manufacturing apparatus 200 scans a laser beam 205 along a plurality of scan line sections 220 that are arranged with a predetermined interval d0 between them, for example, in the direction of the dotted arrow. The interval d0 of the scan line sections 220 is also called the "hatching interval" or "hatching distance". The additive manufacturing apparatus 200 forms a magnetic segment 210 along each scan line section 220. The additive manufacturing apparatus 200 repeats the formation of magnetic segments 210 by stacking another magnetic segment 210 on top of a magnetic segment 210. By irradiating the metal powder 204 with laser beam 205, the metal powder 204 forms a molten pool, and the molten pool solidifies to become a magnetic segment 210. Therefore, the width d1 of the magnetic segment 210 is approximately equal to the width of the molten pool. Figure 3 shows the case where d0 < d1, for example, d0 = d1 / 2.
[0028] In conventional additive manufacturing methods, the spacing between scan lines is generally set to be smaller than the width of the molten pool. As a result, the molten pool is formed across the magnetic material segment 210 being formed and adjacent magnetic material segments 210 in the X-axis direction. Consequently, adjacent magnetic material segments 210 in the X-axis direction are connected to each other with high mechanical strength.
[0029] Figure 4 is a diagram illustrating the formation of a magnetic core according to the second comparative example. As the interval d0 of the scan line section 220 increases, the overlap of the molten pools relating to adjacent magnetic segments 210 decreases. Figure 4 shows the case where d0 = d1.
[0030] Figure 5 is a diagram illustrating the formation of the magnetic core 100 shown in Figure 1. The additive manufacturing apparatus 200 scans a laser beam 205 along a plurality of scan line sections 220 that are arranged with a predetermined interval d0 between them, for example, in the direction of the dotted arrow. According to the manufacturing method of the magnetic core 100 according to this embodiment, the interval d0 of the scan line sections 220 is increased until adjacent magnetic segments 210 in the X-axis direction are separated. In other words, d0 > d1 holds true. The additive manufacturing apparatus 200 forms a plurality of magnetic segments 210 by arranging magnetic material along the plurality of scan line sections 220. The additive manufacturing apparatus 200 repeatedly forms a plurality of magnetic segments 210 by stacking another magnetic segment 210 on top of a magnetic segment 210, thereby forming a plurality of thin plate portions 101. Since d0 > d1, a gap 102 of length d2 is formed between the plurality of thin plate portions 101. As a result, the multiple thin plate portions 101 are arranged periodically with a predetermined gap 102 between them so that the surfaces of adjacent thin plate portions 101 face each other.
[0031] As described above, the width d1 of the magnetic segment 210 is approximately equal to the width of the molten pool. Therefore, the width d1 of the magnetic segment 210 changes depending on the power, spot size, and scanning speed of the laser beam 205. When the power or spot size of the laser beam 205 increases, the width d1 of the magnetic segment 210 also increases. When the scanning speed of the laser beam 205 increases, the width d1 of the magnetic segment 210 decreases. The power, spot size, and scanning speed of the laser beam 205 are set such that the width d1 of each magnetic segment 210, i.e., the thickness of the thin plate portion 101, is smaller than the spacing d0 of the scanning line section 220.
[0032] For example, the thickness of the thin plate portion 101 can be changed by changing the power and scanning speed of the laser beam 205. By reducing the linear energy density of the laser beam 205 (i.e., power / scanning speed), the width d1 of the magnetic material segment 210 is reduced, and therefore the thickness of the thin plate portion 101 is also reduced. The inventors have confirmed that a thin plate portion 101 having a thickness (average value) of, for example, 0.1 to 0.2 mm can be formed using the manufacturing method of the magnetic material core 100 according to this embodiment. This thickness of 0.1 to 0.2 mm is smaller than the thickness of existing general electrical steel sheets, and also smaller than the thickness of other general structures formed using additive manufacturing. The thinner the portion through which the magnetic flux passes, the more effectively eddy current loss can be reduced. Therefore, the magnetic material core 100 according to this embodiment, which comprises a plurality of thin plate portions 101, can achieve lower eddy current loss than existing electrical steel sheets and additive manufactured products.
[0033] The spacing of the scan line sections 220 can also be changed. By repeatedly creating the magnetic core 100 while changing the spacing of the scan line sections 220, a critical spacing can be obtained in which adjacent thin plate portions 101 hardly touch each other. Therefore, a magnetic core 100 with a very high stacking ratio can be formed.
[0034] The additive manufacturing apparatus 200 may repeatedly form multiple magnetic segments 210 by stacking one magnetic segment 210 vertically on top of another magnetic segment 210, i.e., along the Z-axis. In this case, the centerlines of the molten pools relating to the stacked magnetic segments 210 in each of the multiple thin plate portions 101 substantially coincide. This minimizes the thickness of each thin plate portion 101 under given conditions relating to the power, spot size, and scanning speed of the laser beam 205.
[0035] The additive manufacturing apparatus 200 forms the magnetic core 100 according to the parameters of the additive manufacturing method described above.
[0036] Figure 6 shows an exemplary 3D model 100M for forming the magnetic core 100 of Figure 1. According to the manufacturing method of the magnetic core 100 of this embodiment, when forming the magnetic core 100 as shown in Figure 1, the 3D model 100M as shown in Figure 6 may be used instead of a 3D model that includes the geometric shapes of individual thin plate portions 101 and gaps 102. The thickness d1 of each thin plate portion 101 and the length d2 of each gap 102 are automatically determined by setting the interval d0 of the scan line sections 220, the power of the laser beam 205, the spot size, and the scanning speed. The layout of the scan line sections 220 may be automatically determined based on the contour shape of the 3D model 100M, or it may be set according to some additional data.
[0037] [Examples of Magnetic Cores] Figures 7A to 7D show the first to fourth steps, respectively, for forming the magnetic core 100A according to an example of the first embodiment.
[0038] In the example shown in Figures 7A to 7D, a magnetic core 100A, for example, used as a motor core, is formed using the additive manufacturing apparatus 200 of Figure 2. In Figures 7A to 7D, for the sake of simplicity, the housing 201, laser light source 202, drive device 203, and metal powder 204 of Figure 2 are omitted. Similarly, these components are omitted in other drawings showing the process of forming the magnetic core.
[0039] Referring to Figure 7A, after a thin layer of metal powder 204 is filled onto the substrate 110, the additive manufacturing apparatus 200 irradiates the metal powder 204 with laser light 205 along a predetermined scanning line to melt and solidify the metal powder 204.
[0040] FIG. 8 is a diagram showing a layout 221 of scanning lines for forming the magnetic core 100A of FIGS. 7A to 7D. FIG. 9 is a diagram showing another layout 222 of scanning lines for forming the magnetic core 100A of FIGS. 7A to 7D. The layout of the scanning lines may be automatically determined based on the contour shape of the 3D model of the magnetic core 100A. The magnetic flux of the motor generally flows along the contour of the core. Therefore, the layout of the scanning lines can be automatically determined without degrading the magnetic performance of the motor, and the labor of the operator of the additive manufacturing apparatus 200 can be reduced.
[0041] After melting and solidifying the metal powder 204, another layer of the metal powder 204 is filled, and the additive manufacturing apparatus 200 irradiates the laser light 205 along the same scanning line to melt and solidify the metal powder 204. By repeating the filling of the metal powder 204 and the irradiation of the laser light 205, a magnetic core 100A having a desired height is obtained as shown in FIG. 7B.
[0042] Next, referring to FIG. 7C, an insulating film 103 is formed on the surface of the magnetic core 100A by performing electrodeposition coating or the like. The insulating film 103 includes, for example, enamel, polyurethane, polyester, polyamideimide, and the like.
[0043] Next, referring to FIG. 7D, by removing the substrate 110 by wire cutting or the like, a magnetic core 100A covered with the insulating film 103 is obtained. This is used, for example, as the outer core 308 of the motor 301 described later with reference to FIGS. 10 and 11.
[0044] [Configuration of Motor] FIG. 10 is a longitudinal sectional view showing a configuration example of a motor 301 including the outer core 308 of FIG. 7D. FIG. 11 is a cross-sectional view showing a configuration example of a motor 301 including the outer core 308 of FIG. 7D. In the examples of FIGS. 10 and 11, a motor having an inner rotor type configuration with a rotor provided inside the stator, the rotor having magnets, and the stator having windings will be described.
[0045] The motor 301 includes a rotor 302, a stator 303, a pair of bearings 307, and a housing 310. The stator 303 and the bearings 307 are fixed to the housing 310. The rotor 302 is rotatably supported by the pair of bearings 307 inside the stator 303.
[0046] In FIG. 11, for simplicity of illustration, the housing 310 is omitted.
[0047] In the examples of FIGS. 10 and 11, the direction in which the rotation axis 306 extends (the Z direction in FIG. 10 etc.) is called the rotation axis direction, and in the plane orthogonal to this rotation axis direction (the XY plane in FIG. 11 etc.), the direction extending from the center of the rotation axis 306 is called the radial direction, and the direction orbiting around the center is called the circumferential direction.
[0048] The rotor 302 includes an inner core 304, a plurality of magnets 305, and a rotation axis 306. The inner core 304 is a magnetic core having a substantially cylindrical shape. The rotation axis 306 penetrates the inner core 304, and the inner core 304 is mechanically connected to the rotation axis 306. The rotation axis 306 is supported by the pair of bearings 307, and the rotor 302 rotates about the rotation axis 306. The plurality of magnets 305 are permanent magnets provided at equal intervals along the outer circumference of the inner core 304. In the example of FIG. 11, 10 magnets 305 are provided. For example, each magnet 305 has a rectangular parallelepiped shape, and a plurality of substantially rectangular holes are formed at equal intervals along the outer circumference of the inner core 304, and the magnets 305 are inserted into the respective holes. Each magnet 305 becomes a magnetic pole of the rotor 302.
[0049] The inner core 304 mainly contains iron. The inner core 304 may contain, for example, 93.5% or more of iron and 6.5% or less of silicon as components.
[0050] The inner core 304 may be formed from a material such as a powder compact magnetic core material or a soft magnetic metal powder that is easy to mold, using a laminated manufacturing method. Also, the inner core 304 may be formed by laminating a plurality of non-oriented electromagnetic steel sheets in the rotation axis direction.
[0051] The rotor 302 has a magnet-embedded type configuration in which the magnets 305 are embedded inside the inner core 304 so as not to be exposed on the surface of the inner core 304.
[0052] The stator 303 comprises an outer core 308 and a plurality of windings 309. The outer core 308 comprises an annular yoke 321 and a plurality of projections 322 that protrude inward from the yoke 321 and extend radially. In the example shown in Figure 11, the outer core 308 has 12 projections 322. Each projection 322 is arranged at equal intervals along the inner circumference of the yoke 321 such that its tip faces the inner core 304. A winding 309 is wound around each projection 322.
[0053] The inner core 304 and the outer core 308 are formed to be rotatable relative to each other around a common rotation axis 306. The inner core 304 is positioned inside the outer core 308 such that the tips of the multiple projections 322 of the outer core 308 face the outer circumferential surface of the rotor 302 through a gap.
[0054] The rotor 302 and stator 303 configured in this way are arranged inside the housing 310 as shown in Figure 10 to form the motor 301. The rotating shaft 306 extends from the inner core 304 in the direction of the rotating shaft, and one end of the rotating shaft 306 protrudes to the outside of the housing 310 as an output shaft for rotationally driving a load.
[0055] The motor 301 may be a brushless motor driven by a three-phase AC current including U-phase, V-phase, and W-phase, which are 120 degrees out of phase with respect to each other. A current of either the U-phase, V-phase, or W-phase is applied to the multiple windings 309.
[0056] By using the outer core 308 formed using the manufacturing method according to this embodiment, a motor 301 with reduced eddy current loss can be provided.
[0057] [Effects of the First Embodiment] According to the manufacturing method of the magnetic core 100 of this embodiment, by forming a plurality of thin plate portions 101 that are periodically arranged with a predetermined gap 102, it is possible to provide a magnetic core 100 having lower eddy current loss than a bulk magnetic core without excessively complicating the structure.
[0058] According to the manufacturing method of the magnetic core 100 of this embodiment, the thickness of each thin plate portion 101 corresponds to the width of the molten pool formed by a single scan of the laser beam 205. Therefore, according to the manufacturing method of the magnetic core 100 of this embodiment, it is possible to form thin plate portions 101 having a thickness of the lower limit achievable by the laser powder bed fusion method, for example, 0.1 to 0.2 mm.
[0059] According to the manufacturing method of the magnetic core 100 of this embodiment, it is theoretically possible to achieve a higher layer density than existing additive manufacturing methods.
[0060] According to the manufacturing method for the magnetic core 100 of this embodiment, a 3D model having a simpler bulk shape can be used instead of a 3D model including the geometric shapes of individual thin plate portions 101 and gaps 102. Based on the same 3D model, the shape and dimensions of the thin plate portions 101 and gaps 102 can be changed or optimized by changing the spacing d0 of the scan line sections 220, the power of the laser beam 205, the spot size, and the scanning speed. Therefore, it becomes unnecessary to create different 3D models according to different shapes and dimensions. Furthermore, the layout of scan lines for magnetic cores 100 having any shape can be easily or automatically determined using an existing scanning algorithm incorporated into the additive manufacturing apparatus 200. This greatly simplifies the preparation and optimization of additive manufacturing.
[0061] According to the manufacturing method of the magnetic core 100 of this embodiment, it is possible to provide a magnetic core that has a simpler structure than, for example, the core for a rotating electric machine described in Patent Document 1, and has a higher stacking ratio than the core for a rotating electric machine described in Patent Document 1.
[0062] Each layer of the segments formed by the additive manufacturing apparatus 200 solidifies in the order it was scanned. The structure of the segments formed above grows under the influence of the structure of the segments formed below (epitaxial growth). Therefore, the crystal grains have a longitudinal direction in the Z-axis direction, i.e., the manufacturing direction. For example, by analyzing the target magnetic core using a scanning electron microscope, it is possible to verify whether or not the target magnetic core was formed using the manufacturing method according to this embodiment.
[0063] [Second Embodiment] In the second embodiment, a method for manufacturing a magnetic core having a higher stacking ratio than in the first embodiment will be described.
[0064] Figures 12A to 12E show the first to fifth steps, respectively, for forming the magnetic core 100B according to the second embodiment.
[0065] Referring to Figure 12A, the additive manufacturing apparatus 200 forms multiple thin plate portions 101 by repeatedly forming multiple magnetic segments 210 by stacking one magnetic segment 210 on top of another magnetic segment 210, as described with reference to Figure 2.
[0066] Next, referring to Figure 12B, an insulating film 103 is formed on the surface of each thin plate portion 101.
[0067] Next, referring to Figure 12C, the substrate 110 is removed by wire cutting or the like.
[0068] Next, referring to Figure 12D, the length of the gap 102 between the multiple thin plate portions 101 is reduced compared to the length when the multiple thin plate portions 101 were formed (see Figure 12A).
[0069] Next, referring to Figure 12E, the magnetic core 100B is obtained by fixing the entirety of the multiple thin plate portions 101 and the insulating film 103 with resin 104. The resin 104 includes, for example, epoxy resin, adhesive, etc. The resin 104 fills the gap 102 after shrinkage, mechanically connecting the adjacent thin plate portions 101 and ensuring shape stability. The resin 104 also contributes to heat insulation between adjacent thin plate portions 101. The resin 104 may be filled only into the gap 102, rather than covering the entirety of the multiple thin plate portions 101 and the insulating film 103.
[0070] According to the manufacturing method of the magnetic core 100B described with reference to Figures 12A to 12E, by reducing the gap 102, the magnetic core 100B has a higher lamination ratio than when the thin plate portion 101 is formed.
[0071] [Modification of the Second Embodiment] Figures 13A to 13D show the first to fourth steps, respectively, for forming the magnetic core 100C according to a modification of the second embodiment. After the step in Figure 12B, the process may proceed to Figure 13A.
[0072] Referring to Figure 13A, the multiple thin plate portions 101 are inclined with respect to the substrate 110 such that the angle between the substrate 110 and each thin plate portion 101 decreases. As a result, the length of the gap 102 between the multiple thin plate portions 101 is reduced compared to the length when the multiple thin plate portions 101 were formed (see Figure 12A). The multiple thin plate portions 101 may be inclined individually or together.
[0073] Next, referring to Figure 13B, the entirety of the multiple thin plate portions 101 and the insulating film 103 is fixed by the resin 104. Instead of covering the entirety of the multiple thin plate portions 101 and the insulating film 103, the resin 104 may be filled only into the gap 102.
[0074] Next, referring to Figure 13C, the substrate 110 is removed by wire cutting or the like, and the magnetic core 100C is obtained.
[0075] Next, referring to Figure 13D, the magnetic core 100C may be shaped by cutting it with a wire cutter or the like on a plane perpendicular to the surfaces of the thin plate portions 101 at the left and right ends.
[0076] According to the manufacturing method of the magnetic core 100C described with reference to Figures 13A to 13D, by reducing the gap 102, the magnetic core 100C has a higher lamination ratio than when the thin plate portion 101 is formed.
[0077] [Example of the Second Embodiment] Figure 14 is a perspective view showing the configuration of an outer core 308D equipped with a magnetic core 100D according to an embodiment of the second embodiment. The magnetic core 100D is formed by processing the magnetic core 100B in Figure 12E, or the shaped magnetic core 100C as shown in Figure 13D, by wire cutting or the like. For the sake of simplicity in the illustration, the gap 102 and the insulating film 103 are omitted. The magnetic core 100D is provided as the outer core 308D of a motor. By using the outer core 308D formed using the manufacturing method according to this embodiment, it is possible to provide a motor with a higher stacking ratio than in the first embodiment, and therefore with higher efficiency than in the first embodiment.
[0078] [Effects of the Second Embodiment] According to the manufacturing method of the magnetic core of the second embodiment, by reducing the gap 102, it is possible to provide a magnetic core having a higher stacking ratio than in the first embodiment.
[0079] [Third Embodiment] In the third embodiment, an alternative method for manufacturing a magnetic core having a higher stacking ratio than that of the first embodiment will be described.
[0080] Figures 15A to 15F show the first to sixth steps, respectively, for forming the magnetic core 100E according to the third embodiment.
[0081] Referring to Figure 15A, after a thin layer of metal powder 204 is filled onto the substrate 110, the additive manufacturing apparatus 200 irradiates the metal powder 204 with laser light 205 along a predetermined scan line to melt and solidify it. In this embodiment, the scan line is a single curve wound in a spiral, rather than multiple separate sections as shown in Figures 5 and 6. The thin plate portion 101E is formed as a single, spirally wound strip. The gap 102E is also formed spirally along the thin plate portion 101E. The thin plate portion 101E has an inner diameter d11 and an outer diameter d12.
[0082] After melting and solidifying the metal powder 204, another layer of metal powder 204 is filled in, and the additive manufacturing apparatus 200 irradiates the metal powder 204 with laser light 205 along the same scanning line, melting and solidifying the metal powder 204. By repeating the filling of metal powder 204 and the irradiation with laser light 205, a thin plate portion 101E of the desired height is obtained, as shown in Figure 15B.
[0083] Referring to the limited area A shown in Figure 15B, the thin plate portion 101E, which is formed as an integral strip, corresponds to the plurality of thin plate portions 101 described in the first and second embodiments.
[0084] Next, referring to Figure 15C, the substrate 110 is removed by wire cutting or the like.
[0085] Next, referring to Figure 15D, an insulating film 103E is formed on the surface of the thin plate portion 101E by electrodeposition coating or the like.
[0086] Next, referring to Figure 15E, the thin plate portion 101E is deformed so that its inner circumference and outer circumference are brought closer together. The deformed thin plate portion 101E has an inner diameter d13 and an outer diameter d14. Therefore, the following equation holds.
[0087]
[0088] As a result, the gap 102E is reduced compared to when the thin plate portion 101E is formed (see Figure 15A). The thin plate portion 101E may be deformed by fixing the outer edge and moving the inner edge closer to the outer edge, or alternatively, by fixing the inner edge and moving the outer edge closer to the outer edge.
[0089] Next, referring to Figure 15F, the entire thin plate portion 101E and the insulating film 103E are fixed by the resin 104E to obtain the magnetic core 100E. The resin 104E may be filled only into the gap 102E instead of covering the entire thin plate portion 101E and the insulating film 103E.
[0090] According to the manufacturing method of the magnetic core 100E described with reference to Figures 15A to 15F, by reducing the gap 102E, the magnetic core 100E has a higher stacking ratio than when the thin plate portion 101E is formed.
[0091] [Example of the Third Embodiment] Figure 16 is a perspective view showing the configuration of the outer core 308F according to an embodiment of the third embodiment. The outer core 308F comprises a yoke 321F and a plurality of protrusions 322F. The yoke 321F is formed using the manufacturing method of the magnetic core 100E described with reference to Figures 15A to 15F. The plurality of protrusions 322F are formed using the manufacturing method of the magnetic core 100 according to the first embodiment. According to the example in Figure 16, by combining multiple manufacturing methods of the magnetic core, it is possible to reduce the eddy current loss of the outer core 308F and improve the stacking ratio, thereby improving the efficiency of the motor, while improving the degree of freedom in design.
[0092] [Effects of the Third Embodiment] According to the manufacturing method of the magnetic core of the third embodiment, by reducing the gap 102E, it is possible to provide a magnetic core having a higher stacking ratio than in the case of the first embodiment.
[0093] [Other Embodiments] Each of the disclosed embodiments and variations may be combined with other embodiments or variations as appropriate.
[0094] In the embodiment described, a motor having an inner rotor configuration with a rotor inside the stator, a magnet on the rotor, and windings on the stator was described. However, the described principle is also applicable to a motor having an outer rotor configuration with a rotor outside the stator, and also to a motor having windings on the rotor and a magnet on the stator.
[0095] In the embodiments described, a radial flux type motor comprising magnets and windings arranged to face each other in the radial direction was described. However, the principle described is also applicable to an axial flux type motor comprising magnets and windings arranged to face each other in the axial direction.
[0096] The described embodiment is applicable not only to motors but also to other rotating electric machines such as generators, and is also applicable to inductors and transformers.
[0097] The described embodiment may use any other additive manufacturing method, such as directed energy deposition (DED), which has parameters that can be set so that the width of each magnetic material segment 210 is smaller than the spacing of the scan line sections 220, instead of the laser powder bed fusion method.
[0098] In the examples shown in Figures 12A to 12E, the step of fixing the multiple thin plate portions 101 with resin 104 was performed after removing the substrate 110 and reducing the gap 102. On the other hand, if the gap 102 is not reduced, the step of fixing the multiple thin plate portions 101 with resin 104 may be performed before removing the substrate 110. In this case, first, the multiple thin plate portions 101 are formed, then the entire multiple thin plate portions 101 are fixed with resin 104, and then the substrate 110 is removed by wire cutting or the like. The resin 104 may fix the multiple thin plate portions 101 and also act as an insulating film.
[0099] [Summary of Embodiments] The magnetic core and the method for manufacturing the magnetic core according to each embodiment of the present disclosure are configured as follows.
[0100] A method for manufacturing a magnetic core according to a first aspect of the present disclosure includes forming a plurality of thin plate portions made of a magnetic material using an additive manufacturing method. The plurality of thin plate portions are arranged periodically with a predetermined gap between them such that the surfaces of adjacent thin plate portions face each other. Forming the plurality of thin plate portions includes (1) and (2) below: (1) Forming a plurality of magnetic material segments by arranging magnetic material along a plurality of scan line sections of the additive manufacturing method that are arranged at predetermined intervals from each other; (2) Forming the plurality of thin plate portions by repeatedly forming the plurality of magnetic material segments such that another magnetic material segment is stacked on top of a magnetic material segment.
[0101] According to the method for manufacturing a magnetic core according to a second aspect of the present disclosure, in the method for manufacturing a magnetic core according to the first aspect, the spacing between the plurality of scan line sections is greater than the width of each of the plurality of magnetic segments.
[0102] According to a method for manufacturing a magnetic core according to a third aspect of the present disclosure, in the method for manufacturing a magnetic core according to a second aspect, the additive manufacturing method is a laser powder bed fusion method using laser light, and the power, spot size, and scanning speed of the laser light are set such that the width of each of the plurality of magnetic segments is smaller than the interval between the plurality of scanning line sections.
[0103] According to a method for manufacturing a magnetic core according to a fourth aspect of the present disclosure, the method for manufacturing a magnetic core according to one of the first to third aspects further includes forming an insulating film on the plurality of thin plate portions and reducing the length of the gap between the plurality of thin plate portions to a length greater than the length when the plurality of thin plate portions were formed.
[0104] According to a method for manufacturing a magnetic core according to a fifth aspect of the present disclosure, in a method for manufacturing a magnetic core according to a fourth aspect, forming the plurality of thin plate portions includes forming the plurality of thin plate portions on a planar substrate, and reducing the length of the gap between the plurality of thin plate portions includes tilting the plurality of thin plate portions with respect to the planar substrate such that the angle between the planar substrate and each of the plurality of thin plate portions decreases.
[0105] According to the method for manufacturing a magnetic core according to the sixth aspect of the present disclosure, in the method for manufacturing a magnetic core according to the fourth aspect, forming the plurality of thin plate portions includes forming the plurality of thin plate portions as an integral strip wound in a spiral shape, and reducing the length of the gap between the plurality of thin plate portions includes bringing the inner circumference and outer circumference of the strip closer together.
[0106] A magnetic core according to a seventh aspect of this disclosure comprises a plurality of thin plate portions made of magnetic material. The plurality of thin plate portions are arranged periodically with a predetermined gap between them so that the surfaces of adjacent thin plate portions face each other. The plurality of thin plate portions are formed using an additive manufacturing method. The plurality of thin plate portions are formed by repeatedly stacking magnetic segments on top of each other, by arranging magnetic material along a plurality of scan line sections of the additive manufacturing method that are arranged at predetermined intervals from each other.
[0107] According to the eighth aspect of the present disclosure, in the magnetic core according to the seventh aspect, the magnetic core is the core of a motor.
[0108] This disclosure is applicable to a variety of electromagnetic devices, such as, for example, industrial servo motors, drive motors for electric vehicles or plug-in hybrid vehicles, generators, transformers, and inductors.
[0109] 100, 100A-100E Magnetic core 100M 3D model 101, 101E Thin plate portion 102, 102E Gap 103, 103E Insulating film 104, 104E Resin 110 Substrate 200 Additive manufacturing device 201 Housing 202 Laser light source 203 Drive unit 204 Metal powder 205 Laser beam 210 Magnetic segment 220 Scan line section 221 Scan line layout 222 Other scan line layouts 301 Motor 302 Rotor 303 Stator 304 Inner core 305 Magnet 306 Rotating shaft 307 Bearing 308, 308D, 308F Outer core 309 Winding 310 Housing 321, 321F Yoke 322, 322F protrusion
Claims
1. A method for manufacturing a magnetic core, the manufacturing method comprising forming a plurality of thin plate portions made of a magnetic material using an additive manufacturing method, wherein the thin plate portions are periodically arranged with a predetermined gap between them such that the surfaces of adjacent thin plate portions face each other, and the formation of the plurality of thin plate portions comprises forming a plurality of magnetic material segments by arranging magnetic material along a plurality of scan line sections of the additive manufacturing method that are arranged at predetermined intervals from each other, and forming the plurality of thin plate portions by repeatedly forming the plurality of magnetic material segments by stacking another magnetic material segment on top of the magnetic material segments.
2. The method for manufacturing a magnetic core according to claim 1, wherein the spacing between the plurality of scan line sections is greater than the width of each of the plurality of magnetic segment sections.
3. The method for manufacturing a magnetic core according to claim 2, wherein the additive manufacturing method is a laser powder bed fusion method using laser light, and the power, spot size, and scanning speed of the laser light are set such that the width of each of the plurality of magnetic segments is smaller than the interval between the plurality of scanning line sections.
4. The method for manufacturing a magnetic core according to claim 1, further comprising forming an insulating film on the plurality of thin plate portions and reducing the length of the gap between the plurality of thin plate portions to a length greater than the length when the plurality of thin plate portions were formed.
5. The method for manufacturing a magnetic core according to claim 4, wherein forming the plurality of thin plate portions includes forming the plurality of thin plate portions on a planar substrate, and reducing the length of the gap between the plurality of thin plate portions includes tilting the plurality of thin plate portions with respect to the planar substrate such that the angle between the planar substrate and each of the plurality of thin plate portions decreases.
6. The method for manufacturing a magnetic core according to claim 4, wherein forming the plurality of thin plate portions includes forming the plurality of thin plate portions as a helical wound integral strip, and reducing the length of the gap between the plurality of thin plate portions includes bringing the inner circumference and outer circumference of the strip closer together.
7. A magnetic core comprising a plurality of thin plate portions made of a magnetic material, wherein the plurality of thin plate portions are periodically arranged with a predetermined gap between them such that the surfaces of adjacent thin plate portions face each other, wherein the plurality of thin plate portions are formed using an additive manufacturing method, and the plurality of thin plate portions are formed by repeatedly stacking one magnetic plate segment on top of another magnetic plate segment by arranging magnetic material along a plurality of scan line sections of the additive manufacturing method that are arranged at a predetermined interval from each other to form a plurality of magnetic plate segments.
8. The magnetic core according to claim 7, wherein the magnetic core is the core of a motor.