Magnetic core and method for manufacturing same, magnetic core with coil, and rotary electric machine

Abstract

This magnetic core is obtained by integrally molding a first soft magnetic body and a second soft magnetic body having differing average particle diameters, and has a corner part. The magnetic core includes a first region formed from the first soft magnetic body and a second region formed from the second soft magnetic body. The second soft magnetic body has a smaller average particle diameter than the first soft magnetic body. The corner part is included in the second region.

Description

Magnetic core and manufacturing method thereof, magnetic core with coil, and rotating electric machine

[0001] The present invention relates to a magnetic core.

[0002] A known example of a conventional magnetic core is a magnetic core for a motor described in Patent Document 1. The magnetic core includes teeth around which conductor wires are wound. The magnetic core is manufactured by compacting powder.

[0003] JP 2008-160978 A

[0004] During molding of a magnetic core, burrs may form on the surface of the magnetic core. If a conductor wire is wound around the teeth of the magnetic core while burrs remain on the surface of the magnetic core, the conductor wire may come into contact with the burrs and be damaged. To prevent damage to the conductor wire, a finishing process may be performed after molding the magnetic core, in which the surface of the magnetic core is polished with media to remove burrs formed on the surface of the magnetic core. However, if the magnetic core has corners, the media may come into contact with the corners of the magnetic core during this finishing process, causing chipping. If the amount of chipping at the corners is large, the amount of magnetic flux that can pass through the magnetic core during motor operation may be reduced, potentially resulting in deterioration of motor characteristics, such as a decrease in motor output torque.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to make the magnetic core less susceptible to chipping.

[0006] A magnetic core according to one embodiment of the present invention is an integrally molded product of a first soft magnetic material and a second soft magnetic material having different average particle sizes, and has a corner. The magnetic core includes a first region formed of the first soft magnetic material and a second region formed of the second soft magnetic material. The second soft magnetic material has a smaller average particle size than the first soft magnetic material. The corner is included in the second region.

[0007] According to the magnetic core, the second region including the corner of the magnetic core is formed of a second soft magnetic material having a smaller average particle size than the first soft magnetic material. This increases the contact area between the soft magnetic materials per unit volume at the corner. The soft magnetic material deforms during molding. The increased contact area between the soft magnetic materials per unit volume increases the interlocking between the soft magnetic materials during molding, resulting in stronger adhesion between the soft magnetic materials. Furthermore, the increased interlocking between the soft magnetic materials at the corner increases the anchoring effect between the soft magnetic materials, resulting in stronger adhesion between the soft magnetic materials. Therefore, even if a media contacts the corner of the magnetic core during the finishing process, the corner is less likely to chip. Even if the corner of the magnetic core does chip, the small average particle size of the soft magnetic material at the corner minimizes the amount of chipping at the corner.

[0008] When the average particle size of the soft magnetic material is large, the total surface area of ​​the soft magnetic material per unit volume of the region formed by the soft magnetic material is smaller than when the average particle size of the soft magnetic material is small. When the total surface area of ​​the soft magnetic material per unit volume of the region is reduced, the coercivity and hysteresis loss of the region are reduced. Therefore, if the magnetic core is a molded product made only of the first soft magnetic material, the loss of the magnetic core can be reduced. On the other hand, if the magnetic core is a molded product made only of the first soft magnetic material, chipping is likely to occur at the corners. Therefore, according to the above-mentioned magnetic core, a second soft magnetic material with an average particle size smaller than that of the first soft magnetic material is used in the corners. This effectively reduces the amount of chipping in the magnetic core while suppressing an increase in loss of the magnetic core.

[0009] The magnetic core may be used in a rotating electric machine. The magnetic core may include a core back portion, a tooth portion including a tooth main body portion extending from the core back portion, and a tooth tip portion provided at a tip of the tooth main body portion. In this configuration, the tooth tip portion may have a first end face that faces an axial direction along a rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine, and a first side face that faces a circumferential direction centered on the rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine. Furthermore, the corner portion may include an edge-like corner portion formed by the first end face and the first side face, and the edge-like corner portion may be included in the second region.

[0010] According to the above configuration, the second region including the edge corner formed by the first end face and the first side face of the tooth tip is formed of the second soft magnetic material having a small average grain size. This makes the edge corner of the tooth tip less likely to chip. Even if the edge corner of the tooth tip does chip, the small average grain size of the second soft magnetic material can reduce the amount of chipping of the edge corner of the tooth tip.

[0011] In the magnetic core, the tooth tip portion may have a second side surface that faces in a radial direction about a rotation axis of a rotary electric machine when the magnetic core is incorporated into the rotary electric machine. In this configuration, the corner portion may include a pyramidal corner portion formed by the first end face, the first side surface, and the second side surface, and the pyramidal corner portion may be included in the second region.

[0012] According to the above configuration, the second region including the pyramidal portion formed by the first end face, the first side face, and the second side face of the tooth tip is formed of the second soft magnetic material having a small average grain size. This makes the pyramidal portion of the tooth tip less likely to chip. Even if the pyramidal portion of the tooth tip does chip, the small average grain size of the second soft magnetic material can reduce the amount of chipping of the pyramidal portion of the tooth tip.

[0013] In the magnetic core, the core back portion may have a second end face that faces an axial direction along a rotation axis of the rotary electric machine when the magnetic core is incorporated into the rotary electric machine, and a third side face that faces a circumferential direction about the rotation axis of the rotary electric machine when the magnetic core is incorporated into the rotary electric machine. In this configuration, the corner portion may include an edge-like corner portion formed by the second end face and the third side face, and the edge-like corner portion may be included in the second region.

[0014] According to the above configuration, the second region including the edge corner formed by the second end face and the third side face of the core back portion is formed of the second soft magnetic material having a small average particle size. This makes the edge corner of the core back portion less likely to chip. Even if the edge corner of the core back portion does chip, the small average particle size of the second soft magnetic material can reduce the amount of chipping of the edge corner of the core back portion.

[0015] In the magnetic core, the core back portion may have a fourth side surface that faces in a radial direction about a rotation axis of a rotary electric machine when the magnetic core is incorporated into the rotary electric machine. In this configuration, the corner portion may include a pyramidal corner portion formed by the second end face, the third side surface, and the fourth side surface, and the pyramidal corner portion may be included in the second region.

[0016] According to the magnetic core, the second region including the pyramidal corner formed by the second end face, the third side face, and the fourth side face of the core back portion is formed of a second soft magnetic material having a small average particle size. This makes the pyramidal corner of the core back portion less likely to chip. Even if the pyramidal corner of the core back portion does chip, the small average particle size of the second soft magnetic material can reduce the amount of chipping of the pyramidal corner of the core back portion.

[0017] In the magnetic core, the first region and the second region may both be formed in a layered shape. In this configuration, the first region and the second region may be stacked along an axial direction that is along the rotation axis of a rotating electric machine when the magnetic core is incorporated into the rotating electric machine.

[0018] In the magnetic core, the first region made of the first soft magnetic material having a large average particle size and the second region made of the second soft magnetic material having a small average particle size are both formed in layers, which makes it easier to manufacture the magnetic core than when only the corners are made of the second soft magnetic material.

[0019] In the magnetic core, the first region may be sandwiched between the second regions in the axial direction.

[0020] According to the magnetic core, even if the magnetic core has a plurality of corners at different positions in the axial direction, the amount of chipping at the plurality of corners can be reduced.

[0021] A method for manufacturing a magnetic core according to one embodiment of the present invention includes an injection process for injecting first and second soft magnetic powders having different average particle sizes into a mold so that they are layered in the mold, and a compression molding process for compression molding the first and second soft magnetic powders along the direction in which they are layered after the injection process.

[0022] According to the above manufacturing method, the magnetic core can be easily manufactured.

[0023] According to the present invention, the magnetic core can be made less susceptible to chipping.

[0024] FIG. 1 is an external perspective view of a brushless motor 100 using a magnetic core 1. FIG. 2 is a schematic perspective view showing a portion of the brushless motor 100 in a cutaway view. FIG. 3 is a perspective view of the magnetic core 1. FIG. 4 is a perspective view of the core back portion 2. FIG. 5 is a perspective view of the tooth tip portion 32. FIG. 6 is a cross-sectional view of the magnetic core 1. FIG. 7 is a diagram showing an example of the first soft magnetic body SM1 and the second soft magnetic body SM2 in the tooth tip portion 32. FIG. 8 is a schematic cross-sectional view showing the core back portion 2. FIG. 9 is a schematic cross-sectional view showing the tooth tip portion 32. FIG. 10 is a flowchart showing an example of a method for manufacturing the magnetic core 1. FIG. 11 is a cross-sectional view showing an example of a manufacturing process for the magnetic core 1. FIG. 12 is a cross-sectional view showing an example of a manufacturing process for the magnetic core 1. FIG. 13 is a cross-sectional view of the magnetic core 1a. FIG. 14 is a flowchart showing an example of a manufacturing process for the magnetic core 1a. FIG. 15 is a cross-sectional view showing an example of a manufacturing process for the magnetic core 1a. Fig. 16 is a cross-sectional view showing an example of a manufacturing process for the magnetic core 1a. Fig. 17 is a schematic cross-sectional view showing an outline of a tooth tip portion 32 according to a modified example. Fig. 18 is a schematic cross-sectional view showing an outline of a tooth tip portion 32 according to a modified example. Fig. 19 is a schematic cross-sectional view showing an outline of a core back portion 2 according to a modified example.

[0025] [First Embodiment] (Configuration of Brushless Motor 100) First, the configuration of a brushless motor 100 according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is an external perspective view of brushless motor 100 that uses magnetic core 1. Fig. 2 is a schematic perspective view showing brushless motor 100 with a portion cut away.

[0026] In this specification, directions are defined as follows, by way of example. Of the radial directions centered on the rotation axis AR of brushless motor 100, the direction from tooth tip end 32 toward rotation axis AR of brushless motor 100 is defined as a first direction DIR1. First direction DIR1 is the direction toward rotation axis AR of brushless motor 100 when magnetic core 1 is incorporated into brushless motor 100. Of the axial directions along rotation axis AR of brushless motor 100, the direction in which shaft 21 protrudes from opening OP to the outside of housing 12 is defined as a second direction DIR2. Of the circumferential directions centered on rotation axis AR of brushless motor 100, the clockwise direction with respect to rotation axis AR of brushless motor 100 as viewed in second direction DIR2 is defined as a third direction DIR3. The opposite direction of second direction DIR2 is defined as a fourth direction DIR4.

[0027] 2, brushless motor 100 includes rotor 20, stator 10, bearing 11, and housing 12. In this embodiment, brushless motor 100 is an inner rotor type. That is, stator 10 is disposed around rotor 20. Brushless motor 100 is an example of a rotating electric machine according to the present invention.

[0028] The rotor 20 includes a shaft 21 and a rotor member 22. The shaft 21 is cylindrical. The rotor member 22 is cylindrical. The shaft 21 and the rotor member 22 have the same central axis, which forms a rotation axis AR.

[0029] The rotor member 22 has a soft magnetic material 23 and a hard magnetic material 24. The rotor member 22 is attached to the outer peripheral surface of the shaft 21 in the radial direction centered on the rotation axis AR. More specifically, the soft magnetic material 23 is attached to the outer peripheral surface of the shaft 21 in the radial direction centered on the rotation axis AR. The hard magnetic material 24 is attached to the outer peripheral surface of the soft magnetic material 23 in the radial direction centered on the rotation axis AR.

[0030] The soft magnetic material 23 is a soft magnetic material. The hard magnetic material 24 is a magnetized hard magnetic material. The hard magnetic material is magnetized when an external magnetic field is applied. After that, even if the application of the magnetic field is stopped, the hard magnetic material does not lose its magnetization. The hard magnetic material 24 is, for example, a bonded magnet or a sintered magnet.

[0031] The bearing 11 supports the shaft 21 so that it can rotate in the circumferential direction around the rotation axis AR. More specifically, the bearing 11 has a first bearing 11a and a second bearing 11b. In this embodiment, the first bearing 11a and the second bearing 11b are each a ball bearing. The first bearing 11a and the second bearing 11b are each cylindrical and extend along the rotation axis AR. The central axes of the first bearing 11a and the second bearing 11b are the rotation axis AR. In other words, the central axes of the first bearing 11a and the second bearing 11b coincide with the central axis of the shaft 21. However, the first bearing 11a and the second bearing 11b are not limited to being ball bearings.

[0032] The second bearing 11b is positioned further in the fourth direction DIR4 than the first bearing 11a. The first bearing 11a is positioned further in the second direction DIR2 than the rotor member 22. The second bearing 11b is positioned further in the fourth direction DIR4 than the rotor member 22. The second bearing 11b supports the end of the shaft 21 in the fourth direction DIR4.

[0033] The stator 10 includes a coil 13 and a magnetic core 1. That is, in this embodiment, the magnetic core 1 is used in the stator 10 of the brushless motor 100.

[0034] As shown in FIG. 1, the housing 12 has a first housing 12a and a second housing 12b. As shown in FIGS. 1 and 2, the first housing 12a is cylindrical. The central axis of the first housing 12a is the rotation axis AR. The first housing 12a is positioned further in the second direction DIR2 than the second housing 12b. The first housing 12a also has an opening OP. This allows the shaft 21 to protrude from the opening OP in the second direction DIR2. That is, in this embodiment, the brushless motor 100 is a single-shaft type. Note that the brushless motor 100 is not limited to a single-shaft type and may be a double-shaft type.

[0035] The first housing 12a supports the first bearing 11a, the plurality of magnetic cores 1, and the plurality of coils 13. The second housing 12b supports the second bearing 11b. In this embodiment, the material of each of the first housing 12a and the second housing 12b is SUS (Steel Use Stainless Steel). However, the material of each of the first housing 12a and the second housing 12b is not limited to SUS, and any material with high rigidity may be used.

[0036] The multiple coils 13 and the multiple magnetic cores 1 are arranged in the circumferential direction around the rotation axis AR. Note that in Fig. 2, reference symbols are assigned to only representative magnetic cores 1 and coils 13 among the multiple magnetic cores 1 and the multiple coils 13. The multiple magnetic cores 1 are arranged around the hard magnetic material 24 with a gap between them.

[0037] The coil 13 is made of a conductive material such as copper. The coil 13 has a structure in which the surface of a copper wire is covered with an insulating coating. Because the surface of the copper wire is covered with an insulating coating, the coil 13 is electrically insulated from the magnetic core 1. However, at the two end portions of the coil 13, the surface of the copper wire is not covered with the insulating coating and the copper wire is exposed.

[0038] A current is supplied to the coil 13 from a power supply (not shown). When a current flows through the coil 13, the coil 13 generates a magnetic field. The magnetic core 1 is magnetized by both the magnetic field generated by the hard magnetic material 24 and the magnetic field generated by the coil 13. The rotation of the rotor 20 is controlled by controlling the current supplied from the power supply (not shown).

[0039] (Configuration of magnetic core 1) The configuration of the magnetic core 1 according to the first embodiment of the present invention will be described below with reference to the drawings. First, the appearance of the magnetic core 1 will be described. Fig. 3 is a perspective view of the magnetic core 1. Fig. 4 is a perspective view of the core back portion 2. Fig. 5 is a perspective view of the tooth tip portion 32.

[0040] As shown in FIG. 3 , the magnetic core 1 includes a core back portion 2 and teeth 3. The magnetic core 1 also has corners C1 and C2. The corners C1 and C2 are formed at the ends of the magnetic core 1 used in the brushless motor 100. Note that in FIG. 3 , only representative corners C1 and C2 are denoted by reference numerals. The teeth 3 include teeth main bodies 31 extending from the core back portion 2 and teeth tip portions 32 provided at the tips of the teeth main bodies 31. More specifically, the teeth main bodies 31 extend from the core back portion 2 in the first direction DIR1. As shown in FIG. 2 , the coils 13 are wound around the teeth main bodies 31. When the magnetic core 1 is incorporated into the brushless motor 100, the teeth tip portions 32 face the hard magnetic material 24 of the rotor 20 across an air gap.

[0041] As shown in FIG. 4 , the core back portion 2 has an end face ES21 facing the second direction DIR2, an end face ES22 facing the fourth direction DIR4, a side face SS41 facing the opposite direction to the first direction DIR1, a side face SS42 facing the first direction DIR1, a side face SS31 facing the third direction DIR3, and a side face SS32 facing the opposite direction to the third direction DIR3. When the magnetic core 1 is incorporated into the brushless motor 100, the side face SS41 forms part of the outer peripheral surface of the stator 10. The side face SS31 is magnetically connected to the side face of the adjacent magnetic core 1 facing the opposite direction to the third direction DIR3. The side face SS32 is magnetically connected to the side face of the adjacent magnetic core 1 facing the third direction DIR3. The end face ES21 corresponds to the second end face according to the present invention. The end face ES22 may correspond to the second end face according to the present invention. The side face SS31 may correspond to the third side face according to the present invention. The side face SS32 may correspond to the third side face according to the present invention. The side face SS41 may correspond to the fourth side face according to the present invention. The side face SS42 may correspond to the fourth side face according to the present invention.

[0042] The corner C1 is formed in the core back portion 2. In the present embodiment, the corner C1 includes an edge-like corner EC1 formed by the end face ES21 and the side face SS31, an edge-like corner EC2 formed by the end face ES21 and the side face SS32, an edge-like corner EC3 formed by the end face ES21 and the side face SS41, an edge-like corner EC4 formed by the end face ES21 and the side face SS42, a pyramidal corner CC1 formed by the end face ES21, the side face SS31, and the side face SS41, a pyramidal corner CC2 formed by the end face ES21, the side face SS31, and the side face SS42, a pyramidal corner CC3 formed by the end face ES21, the side face SS32, and the side face SS41, and a pyramidal corner CC4 formed by the end face ES21, the side face SS32, and the side face SS42.

[0043] In this embodiment, the edge-like corner EC1 is a part of the edge of the end face ES21, near the part that contacts the side face SS31. The edge-like corner EC2 is a part of the edge of the end face ES21, near the part that contacts the side face SS32. The edge-like corner EC3 is a part of the edge of the end face ES21, near the part that contacts the side face SS41. The edge-like corner EC4 is a part of the edge of the end face ES21, near the part that contacts the side face SS42.

[0044] In this embodiment, pyramidal corner CC1 is near the apex formed by end face ES21, side face SS31, and side face SS41. Pyramid corner CC2 is near the apex formed by end face ES21, side face SS31, and side face SS42. Pyramid corner CC3 is near the apex formed by end face ES21, side face SS32, and side face SS41. Pyramid corner CC4 is near the apex formed by end face ES21, side face SS32, and side face SS42.

[0045] As shown in FIG. 5 , each tooth tip portion 32 has an end face ES11 facing the second direction DIR2, an end face ES12 facing the fourth direction DIR4, a side face SS21 facing the opposite direction to the first direction DIR1, a side face SS22 facing the first direction DIR1, a side face SS11 facing the third direction DIR3, and a side face SS12 facing the opposite direction to the third direction DIR3. When the magnetic core 1 is incorporated into the brushless motor 100, the side face SS22 faces the hard magnetic material 24 of the rotor 20 across an air gap. The end face ES11 corresponds to the first end face according to the present invention. Note that the end face ES12 may also correspond to the first end face according to the present invention. The side face SS11 corresponds to the first side face according to the present invention. Note that the side face SS12 may also correspond to the first side face according to the present invention. The side face SS21 corresponds to the second side face according to the present invention. The side surface SS22 may correspond to the second side surface according to the present invention.

[0046] Corner portion C2 is formed at tooth tip portion 32. In the present embodiment, corner portion C2 includes an edge-like corner portion EC5 formed by end face ES11 and side face SS11, an edge-like corner portion EC6 formed by end face ES11 and side face SS12, an edge-like corner portion EC7 formed by end face ES11 and side face SS21, an edge-like corner portion EC8 formed by end face ES11 and side face SS22, a pyramidal corner portion CC5 formed by end face ES11, side face SS11, and side face SS21, a pyramidal corner CC6 formed by end face ES11, side face SS11, and side face SS22, a pyramidal corner CC7 formed by end face ES11, side face SS12, and side face SS21, and a pyramidal corner CC8 formed by end face ES11, side face SS12, and side face SS22.

[0047] In this embodiment, the edge-like corner EC5 is a part of the edge of the end face ES11, near the part that contacts the side face SS11. The edge-like corner EC6 is a part of the edge of the end face ES11, near the part that contacts the side face SS12. The edge-like corner EC7 is a part of the edge of the end face ES11, near the part that contacts the side face SS21. The edge-like corner EC8 is a part of the edge of the end face ES11, near the part that contacts the side face SS22.

[0048] In this embodiment, pyramidal corner CC5 is near the apex formed by end face ES11, side face SS11, and side face SS21. Pyramid corner CC6 is near the apex formed by end face ES11, side face SS11, and side face SS22. Pyramid corner CC7 is near the apex formed by end face ES11, side face SS12, and side face SS21. Pyramid corner CC8 is near the apex formed by end face ES11, side face SS12, and side face SS22.

[0049] Next, the structure of the magnetic core 1 will be described. FIG. 6 is a cross-sectional view of the magnetic core 1. FIG. 7 is a diagram showing an example of the first soft magnetic body SM1 and the second soft magnetic body SM2 in the tooth tip portion 32. Note that FIG. 7 is an example of an image of the tooth tip portion 32 taken with an electron microscope (SEM). FIG. 8 is a schematic cross-sectional view showing an outline of the core back portion 2. FIG. 9 is a schematic cross-sectional view showing an outline of the tooth tip portion 32. Note that in FIGS. 7 to 9, reference symbols are assigned only to representative first soft magnetic body SM1 and second soft magnetic body SM2 out of the first soft magnetic body SM1 and the second soft magnetic body SM2. Furthermore, for the sake of explanation, in FIGS. 8 and 9, the shapes of the first soft magnetic body SM1 and the second soft magnetic body SM2 are indicated by circles, respectively.

[0050] The core back portion 2 and the teeth portion 3 are included in the magnetic core 1, which is a single member. A single member means a member having a structure that makes it impossible to separate the core back portion 2 and the teeth portion 3 without damaging the core.

[0051] The magnetic core 1 is an integrally molded product of a first soft magnetic body SM1 and a second soft magnetic body SM2. The magnetic core 1 is produced by, for example, compression molding. After compression molding, the first soft magnetic body SM1 and the second soft magnetic body SM2 have different average particle sizes. After compression molding, the particle size of the second soft magnetic body SM2 is smaller than the particle size of the first soft magnetic body SM1. The material of the first soft magnetic body SM1 and the second soft magnetic body SM2 is, for example, pure iron powder. Pure iron powder is iron powder with a purity of approximately 99.90-99.95% and a carbon content of 0.02% or less.

[0052] The surface of the pure iron powder may be coated with an insulating material. The materials of the first soft magnetic body SM1 and the second soft magnetic body SM2 are not limited to pure iron powder. The first soft magnetic body SM1 and the second soft magnetic body SM2 may each be a mixture of iron powder and epoxy resin powder, which is an example of binder powder.

[0053] As shown in Figure 6, the magnetic core 1 has a first region A1 formed of a first soft magnetic material SM1 and a second region A2 formed of a second soft magnetic material SM2. The corners C1 and C2 are each included in the second region A2. The edge-shaped corners EC1 to EC8 are each included in the second region A2. The pyramidal corners CC1 to CC8 are each included in the second region A2. In this embodiment, the first region A1 and the second region A2 are both formed in layers. More specifically, the first region A1 and the second region A2 are stacked along the fourth direction DIR4.

[0054] The tooth main body 31 is included in the first region A1. Also, a portion P2 of the core back portion 2 that overlaps with the tooth main body 31 when viewed in the first direction DIR1 is included in the first region A1. Also, a portion P3 of the tooth tip end 32 that overlaps with the tooth main body 31 when viewed in the first direction DIR1 is included in the first region A1.

[0055] In practice, most of the first and second soft magnetic bodies SM1 and SM2 are non-spherical. Furthermore, as shown in FIG. 7 , the shapes of the first and second soft magnetic bodies SM1 and SM2 are irregular. Therefore, rather than extracting one first soft magnetic body SM1 in the first region A1 and one second soft magnetic body SM2 in the second region A2 and comparing their particle sizes, the average particle sizes of the multiple first soft magnetic bodies SM1 in the first region A1 and the multiple second soft magnetic bodies SM2 in the second region A2 should be compared. An example of a method for calculating the average particle sizes is described below.

[0056] An electron microscope (SEM) is used to calculate the average particle size of each of the first soft magnetic material SM1 and the second soft magnetic material SM2. First, a cross-section of the soft magnetic material is photographed using the SEM so that at least 50 or more powder particles are included. Next, the total area A of the powder cross-sections in the image photographed by the SEM and the number N of powder particles in the image photographed by the SEM are calculated. Next, the total area A of the powder cross-sections is divided by the number N of powder particles to calculate the average cross-sectional area S1 of the powder. Next, the average cross-sectional area S1 of the powder is divided by pi, and the square root r is calculated. Finally, the square root r is multiplied by 2 to determine the average particle size of the soft magnetic material.

[0057] In the example shown in Figures 8 and 9, the median of the particle size distribution of the iron powder used to make the first soft magnetic body SM1 is 226.8 µm, and the median of the particle size distribution of the iron powder used to make the second soft magnetic body SM2 is 136.1 µm. In this example, the median of the particle size distribution of the iron powder used to make the second soft magnetic body SM2 is approximately 60% of the median of the particle size distribution of the iron powder used to make the first soft magnetic body SM1. The size relationship between the diameters does not change before and after compression. Therefore, in the magnetic core 1, the average particle size of the second soft magnetic body SM2 is smaller than the average particle size of the first soft magnetic body SM1. More specifically, as shown in FIG. 8, the average grain size of the second soft magnetic material SM2 at the pyramidal corner CC2 and the average grain size of the second soft magnetic material SM2 at the pyramidal corner CC4 are smaller than the average grain size of the first soft magnetic material SM1 at the corner formed by the end face ES22, the side face SS31, and the side face SS42, and the average grain size of the first soft magnetic material SM1 at the corner formed by the end face ES22, the side face SS32, and the side face SS42, respectively. Furthermore, as shown in Figure 9, the average grain size of the second soft magnetic material SM2 at the pyramidal corner CC6 and the average grain size of the second soft magnetic material SM2 at the pyramidal corner CC8 are smaller than the average grain size of the first soft magnetic material SM1 at the corner formed by the end face ES12, the side face SS11, and the side face SS22, and the average grain size of the first soft magnetic material SM1 at the corner formed by the end face ES12, the side face SS12, and the side face SS22, respectively.

[0058] The median of the particle size distribution of the iron powder that is the material of the second soft magnetic body SM2 is not limited to approximately 60% of the median of the particle size distribution of the iron powder that is the material of the first soft magnetic body SM1. In order to effectively reduce the amount of chipping of the magnetic core 1 while suppressing an increase in loss in the magnetic core 1, it is preferable that the average particle size of the second soft magnetic body SM2 be greater than 10% and less than 65% of the average particle size of the first soft magnetic body SM1.

[0059] 8 and 9, the grain size of the first soft magnetic body SM1 is the diameter D1 of the first soft magnetic body SM1. The grain size of the second soft magnetic body SM2 is the diameter D2 of the second soft magnetic body SM2. The diameter D2 of the second soft magnetic body SM2 is smaller than the diameter D1 of the first soft magnetic body SM1.

[0060] In the magnetic core 1, the second region A2, which includes the corners C1 and C2 of the magnetic core 1, is formed of a second soft magnetic material SM2 having a smaller average particle size than the first soft magnetic material SM1. This increases the contact area between the soft magnetic materials per unit volume at the corners C1 and C2. More specifically, if the average particle size of the first soft magnetic material SM1 is 1, the average volume of the first soft magnetic material SM1 is approximately 4.2, and the average surface area of ​​the first soft magnetic material SM1 is 12.6. Therefore, the average surface area per unit volume of the first soft magnetic material SM1 is 3. On the other hand, if the average particle size of the second soft magnetic material SM2 is 0.65, the average volume of the second soft magnetic material SM2 is 1.2, and the average surface area of ​​the first soft magnetic material SM1 is 5.3. Therefore, the average surface area per unit volume of the second soft magnetic material SM2 is 4.6. In this way, the smaller the average particle size of the soft magnetic material, the larger the average surface area per unit volume of the soft magnetic material.

[0061] Furthermore, soft magnetic materials deform during molding and tend to interlock with each other. Therefore, when the contact area between the soft magnetic materials per unit volume at the corners C1 and C2 increases, the soft magnetic materials interlock more during molding, resulting in stronger adhesion between the soft magnetic materials. Furthermore, the increased interlocking between the second soft magnetic materials SM2 at the corners C1 and C2 enhances the anchoring effect between the second soft magnetic materials SM2. That is, the microscopic irregularities on the surface of the second soft magnetic material SM2 interlock more frequently, resulting in stronger adhesion between the second soft magnetic materials SM2. Therefore, even if the media contacts the corners C1 and C2 of the magnetic core 1 during the finishing process, the corners C1 and C2 are less likely to chip. Even if the corners C1 and C2 of the magnetic core 1 are chipped, the small average particle size of the second soft magnetic material SM2 at the corners C1 and C2 minimizes the amount of chipping at the corners C1 and C2.

[0062] When the average particle size of the soft magnetic material is large, the total surface area of ​​the soft magnetic material per unit volume in the region formed by the soft magnetic material is smaller than when the average particle size of the soft magnetic material is small. As a result, when the total surface area of ​​the soft magnetic material per unit volume in the region is reduced, the coercivity and hysteresis loss in the region are reduced. Therefore, if the magnetic core is a molded product made only of the first soft magnetic material SM1, the loss of the magnetic core can be reduced. On the other hand, if the magnetic core is a molded product made only of the first soft magnetic material SM1, chipping is likely to occur at the corners. Therefore, according to the magnetic core 1, the second soft magnetic material SM2 is used at the corners C1 and C2. Furthermore, portions P2 of the tooth main body 31 and the core back portion 2 that overlap with the tooth main body 31 when viewed in the first direction DIR1, and portions P3 of the tooth tip portion 32 that overlap with the tooth main body 31 when viewed in the first direction DIR1, allow a larger amount of magnetic flux to pass through than the corners C1 and C2 when the magnetic core 1 is incorporated into the brushless motor 100. Therefore, according to the magnetic core 1, the tooth main body 31, portion P2 of the core back portion 2, and portion P3 of the tooth tip portion 32 use the first soft magnetic material SM1. This makes it possible to effectively reduce the amount of chipping in the magnetic core 1 while suppressing an increase in loss in the magnetic core 1.

[0063] In the magnetic core 1, the second region A2, which includes the edge-like corners EC5 to EC8 of the tooth tip portions 32, is formed of the second soft magnetic material SM2. This makes the edge-like corners EC5 to EC8 of the tooth tip portions 32 less likely to chip. Even if the edge-like corners EC5 to EC8 of the tooth tip portions 32 do chip, the small average particle size of the second soft magnetic material SM2 reduces the amount of chipping of the edge-like corners EC5 to EC8 of the tooth tip portions 32.

[0064] The second region A2 may include only one of the edge-like corners of the tooth tip portion 32. In this case, there is an effect that the edge-like corner of the tooth tip portion 32 is less likely to chip.

[0065] In the magnetic core 1, the second region A2 including the pyramidal corners CC5 to CC8 of the tooth tip portions 32 is formed of the second soft magnetic material SM2. This makes the pyramidal corners CC5 to CC8 of the tooth tip portions 32 less likely to chip. Even if the pyramidal corners CC5 to CC8 of the tooth tip portions 32 are chipped, the small average particle size of the second soft magnetic material SM2 can reduce the amount of chipping of the pyramidal corners CC5 to CC8 of the tooth tip portions 32.

[0066] In the magnetic core 1, the second region A2, which includes the edge-like corners EC1 to EC4 of the core back portion 2, is formed of the second soft magnetic material SM2. This makes it difficult for the edge-like corners EC1 to EC4 of the core back portion 2 to chip. Even if the edge-like corners EC1 to EC4 of the core back portion 2 are chipped, the amount of chipping of the edge-like corners EC1 to EC4 of the core back portion 2 can be reduced because the average particle size of the second soft magnetic material SM2 is small.

[0067] In the magnetic core 1, the second region A2 including the pyramidal corners CC1 to CC4 of the core back portion 2 is formed of the second soft magnetic material SM2. This makes it difficult for the pyramidal corners CC1 to CC4 of the core back portion 2 to chip. Even if the pyramidal corners CC1 to CC4 of the core back portion 2 are chipped, the amount of chipping of the pyramidal corners CC1 to CC4 of the core back portion 2 can be reduced because the average particle size of the second soft magnetic material SM2 is small.

[0068] The second region A2 may include only one of the pyramidal corners of the core back portion 2. In this case, there is an effect that the one of the pyramidal corners of the core back portion 2 is less likely to chip.

[0069] In the magnetic core 1, the first region A1 and the second region A2 are stacked along the fourth direction DIR4. Therefore, the magnetic core can be manufactured more easily than when only the corners are formed of the second soft magnetic material SM2. Furthermore, when the magnetic core 1 is assembled into the brushless motor 100, the magnetic core 1 is aligned in the third direction DIR3. Therefore, magnetic flux passing through the interior of the magnetic core 1 flows along the third direction DIR3 or the direction opposite to the third direction DIR3. By stacking the first region A1 and the second region A2 along the fourth direction DIR4, the region in the brushless motor 100 through which more magnetic flux flows can be the first region A1, which is formed of the first soft magnetic material SM1 with a larger average particle size. Therefore, the amount of chipping in the magnetic core 1 can be effectively reduced while suppressing an increase in loss in the magnetic core 1.

[0070] (Method for manufacturing magnetic core 1) Hereinafter, a method for manufacturing the magnetic core 1 according to the first embodiment of the present invention will be described with reference to the drawings. Fig. 10 is a flowchart showing an example of a method for manufacturing the magnetic core 1. Figs. 11 and 12 are cross-sectional views showing an example of a manufacturing process of the magnetic core 1.

[0071] 10 and 11 , first, the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 are injected into the mold DI so that they are layered in the mold DI ( FIG. 10 : step S11, injection step). Before compaction, the particle size of the second soft magnetic powder SMP2 is smaller than the particle size of the first soft magnetic powder SMP1. For example, by injecting the second soft magnetic powder SMP2 into the mold DI and then injecting the first soft magnetic powder SMP1 into the mold DI, the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 can be layered in the mold DI.

[0072] 10 and 12 , after the injection step, the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 are compression-molded along the direction in which they are stacked ( FIG. 10 : step S12, compression molding step). The compression molding causes deformation of the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2, but the change in average particle size is minimal. For example, if the first soft magnetic powder SMP1 is stacked on top of the second soft magnetic powder SMP2 in the injection step, the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 are compressed from above using a punch PU to compression-mold them. In this case, the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 may also be compressed from below using a punch PU to compression-mold them. The bottom surface of the punch PU has projections and recesses, so that the core back portion 2 and the teeth portion 3 can be formed, and the magnetic core 1 can be obtained.

[0073] According to the manufacturing method of the magnetic core 1, the magnetic core 1 can be easily manufactured without complicating the manufacturing process. After the compression molding process, a finishing process may be performed in which the surface of the magnetic core 1 is polished with media to remove burrs formed on the surface of the magnetic core 1. Even in this case, the magnetic core 1 is less likely to chip during the finishing process.

[0074] [First Modification] (Configuration of Magnetic Core 1a) The configuration of the magnetic core 1a according to a first modification of the present invention will be described below with reference to the drawings. Fig. 13 is a cross-sectional view of the magnetic core 1a. Note that for the magnetic core 1a according to the first modification, only the differences from the magnetic core 1 according to the first embodiment will be described, and the rest will be omitted.

[0075] The magnetic core 1a differs from the magnetic core 1 in that the first region A1 is sandwiched between the second regions A2 in the fourth direction DIR4. That is, the magnetic core 1a has one first region A1 and two second regions A2.

[0076] In this modification, the magnetic core 1 a has a symmetrical structure with respect to a plane perpendicular to the straight line along the fourth direction DIR4, and therefore, a description of the portion of the magnetic core 1 a located closer to the second direction DIR2 than the tooth main body 31 will be omitted.

[0077] The magnetic core 1a described above also exhibits the same effects as the magnetic core 1. Furthermore, with the magnetic core 1a, the first region A1 is sandwiched between the second regions A2 in the fourth direction DIR4, so that more corners are less likely to chip than with the magnetic core 1. Therefore, the magnetic core 1a is less likely to chip than the magnetic core 1.

[0078] (Method for manufacturing magnetic core 1a) A method for manufacturing the magnetic core 1a according to the first modified example of the present invention will be described below with reference to the drawings. Fig. 14 is a flowchart showing an example of a method for manufacturing the magnetic core 1a. Figs. 15 and 16 are cross-sectional views showing an example of a manufacturing process for the magnetic core 1a. Note that, with regard to the method for manufacturing the magnetic core 1a according to the first modified example, only the parts that differ from the method for manufacturing the magnetic core 1 according to the first embodiment will be described, and the rest will be omitted.

[0079] 14 and 15 , first, a first soft magnetic powder SMP1 and a second soft magnetic powder SMP2 having different average particle sizes are injected into a mold DI so that they are layered in the order of second soft magnetic powder SMP2, first soft magnetic powder SMP1, and second soft magnetic powder SMP2 ( FIG. 14 : step S21, injection step). For example, the second soft magnetic powder SMP2 is injected into the mold DI, then the first soft magnetic powder SMP1 is injected into the mold DI, then a punch PU1 is provided on the first soft magnetic powder SMP1, and then the second soft magnetic powder SMP2 is injected into the mold DI. This makes it possible to obtain a layered state of the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 in the order of second soft magnetic powder SMP2, first soft magnetic powder SMP1, and second soft magnetic powder SMP2 in the mold DI.

[0080] 14 and 15 , after the injection step, the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 are compression-molded along the direction in which they were stacked ( FIG. 14 : step S22, compression molding step). For example, if the second soft magnetic powder SMP2, the first soft magnetic powder SMP1, and the second soft magnetic powder SMP2 are stacked in this order from top to bottom in the injection step, the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 are compressed from above by punches PU1, PU2, and PU3, and the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 are compression-molded. In this case, the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 may also be compressed from below by punches PU1, PU2, and PU3, and the first soft magnetic powder SMP1 and the second soft magnetic powder SMP2 may be compression-molded. By using punches PU1, PU2, and PU3 depending on the location of the magnetic core 1a, the core back portion 2 and the teeth portion 3 can be formed, and the magnetic core 1a can be obtained.

[0081] According to the manufacturing method of the magnetic core 1a, the magnetic core 1a can be easily manufactured without complicating the manufacturing process.

[0082] [Other Embodiments] The magnetic core according to the present invention is not limited to the magnetic core 1 and the magnetic core 1a, and can be modified within the scope of the gist thereof. Furthermore, the configurations of the magnetic core 1 and the magnetic core 1a may be arbitrarily combined. Furthermore, the manufacturing method of the magnetic core according to the present invention is not limited to the manufacturing method of the magnetic core 1 and the manufacturing method of the magnetic core 1a, and can be modified within the scope of the gist thereof. Furthermore, the manufacturing method of the magnetic core 1 and the manufacturing method of the magnetic core 1a may be arbitrarily combined.

[0083] The rotating electric machine according to the present invention only needs to include the magnetic core 1 or the magnetic core 1a, and may also include brushes. The rotating electric machine according to the present invention may also be an outer rotor type, i.e., the rotor 20 may be disposed around the stator 10.

[0084] The rotating electric machine according to the present invention may have a structure in which the rotor is rotated by electricity, or may have a structure in which electricity is generated by the rotation of the rotor. The rotating electric machine according to the present invention includes a brushless motor, a permanent magnet synchronous motor, a permanent magnet synchronous generator, etc.

[0085] The magnetic core and the magnetic core with a coil according to the present invention may be used as part of a rotor.

[0086] 17 and 18 are schematic cross-sectional views showing tooth tip portions 32 according to modified examples. FIG. 19 is a schematic cross-sectional view showing a core back portion 2 according to modified examples. Note that in FIGS. 17 to 19, reference symbols are assigned only to representative first and second soft magnetic bodies SM1 and SM2. As shown in FIGS. 17 and 18, the first region A1 and the second region A2 do not necessarily have to be formed in layers. For example, as shown in FIG. 17, only one edge-like corner may be included in the second region A2. FIG. 17 shows an example in which only the edge-like corner EC8 of the edge-like corners EC1 to EC8 is included in the second region A2. The modified example shown in FIG. 17 has the effect of making the edge-like corner EC8 less likely to chip.

[0087] Also, for example, as shown in Fig. 18, only one pyramidal corner may be included in the second region A2. Fig. 18 shows an example in which only pyramidal corner CC5 of pyramidal corners CC1 to CC8 is included in the second region A2. In the case of the modified example shown in Fig. 18, the effect is that pyramidal corner CC5 is less likely to chip.

[0088] When the first region A1 and the second region A2 are both formed in layers, the first region A1 and the second region A2 do not have to be stacked along the fourth direction DIR4. For example, as shown in FIG. 19 , the first region A1 and the second region A2 may be stacked along the first direction DIR1.

[0089] The present invention has the following configuration.

[0090] (1) A magnetic core having a corner portion, which is an integral molding of a first soft magnetic body and a second soft magnetic body having different average particle sizes, the magnetic core comprising: a first region formed of the first soft magnetic body; and a second region formed of the second soft magnetic body, the second soft magnetic body having a smaller average particle size than the first soft magnetic body, and the corner portion being included in the second region.

[0091] (2) A magnetic core according to (1), used in a rotating electric machine, comprising: a core back portion; and a teeth portion including a tooth main body portion extending from the core back portion and a tooth tip portion provided at the tip of the tooth main body portion, wherein the tooth tip portion has: a first end face that faces an axial direction along the rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine; and a first side face that faces a circumferential direction centered on the rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine, wherein the corner portion includes an edge-like corner portion formed by the first end face and the first side face, and the edge-like corner portion is included in the second region.

[0092] (3) The magnetic core described in (2), wherein the tooth tip has a second side surface that faces radially around the rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine, and the corner portion includes a pyramidal corner portion formed by the first end face, the first side surface, and the second side surface, and the pyramidal corner portion is included in the second region.

[0093] (4) A magnetic core according to any one of (1) to (3), used in a rotating electric machine, comprising: a core back portion; and a teeth portion including a tooth main body portion extending from the core back portion and a tooth tip portion provided at the tip of the tooth main body portion, wherein the core back portion has: a second end face that faces an axial direction along the rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine; and a third side face that faces a circumferential direction centered on the rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine, wherein the corner portion includes an edge-like corner portion formed by the second end face and the third side face, and the edge-like corner portion is included in the second region.

[0094] (5) The magnetic core according to (4), wherein the core back portion has a fourth side surface that faces in a radial direction centered on a rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine, and the corner portion includes a pyramidal corner portion formed by the second end face, the third side surface, and the fourth side surface, and the pyramidal corner portion is included in the second region.

[0095] (6) A magnetic core according to any one of (1) to (5), which is used in a rotating electric machine, wherein the first region and the second region are both formed in layers, and the first region and the second region are stacked along an axial direction along a rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine.

[0096] (7) The magnetic core according to (6), wherein the first region is sandwiched between the second regions in the axial direction.

[0097] (8) The magnetic core according to any one of (1) to (7), wherein the average grain size of the second soft magnetic material is greater than 10% and not more than 65% of the average grain size of the first soft magnetic material.

[0098] (9) A magnetic core with a coil, comprising: the magnetic core according to (2) or (3); and a coil wound around the tooth main body portion.

[0099] (10) A rotating electrical machine comprising the magnetic core according to any one of (1) to (8).

[0100] (11) A method for manufacturing a magnetic core according to any one of (1) to (8), comprising: an injection step of injecting a first soft magnetic powder and a second soft magnetic powder having different average particle sizes into a mold so that the first soft magnetic powder and the second soft magnetic powder are stacked in layers within the mold; and a compression molding step of compression molding the first soft magnetic powder and the second soft magnetic powder along the direction in which the first soft magnetic powder and the second soft magnetic powder are stacked after the injection step.

[0101] DESCRIPTION OF SYMBOLS 1, 1a: Magnetic core 2: Core back portion 3: Teeth portion 10: Stator 11: Bearing 11a: First bearing 11b: Second bearing 12: Housing 12a: First housing 12b: Second housing 13: Coil 20: Rotor 21: Shaft 22: Rotor member 23: Soft magnetic material 24: Hard magnetic material 31: Teeth main body portion 32: Teeth tip portion 100: Brushless motor A1: First region A2: Second region AR: Rotating shaft C1, C2: Corner portion CC1 to CC8: Pyramidal corner portion DI: Mold DIR1: First direction DIR2: Second direction DIR3: Third direction DIR4: Fourth direction EC1 to EC8: Edge-shaped corner portion ES11, ES12, ES21, ES22: End face OP: Opening P2, P3: Parts PU, PU1, PU2, PU3: Punch SM1: First soft magnetic material SM2: Second soft magnetic material SMP1: First soft magnetic powder SMP2: Second soft magnetic powder SS11, SS12, SS21, SS22, SS31, SS32, SS41, SS42: Side surfaces

Claims

1. A magnetic core comprising a first soft magnetic material and a second soft magnetic material having different average particle sizes, having corners, and used as a magnetic core in a rotating electrical machine. Core back section, A tooth portion including a tooth body portion extending from the core back portion and a tooth tip portion provided at the tip of the tooth body portion, It is equipped with, The tip of the tooth is, A first end face that, when the magnetic core is incorporated into the rotating electric machine, will face in the axial direction along the rotation axis of the rotating electric machine, When the magnetic core is incorporated into the rotating electric machine, the first side surface will face the circumferential direction centered on the rotation axis of the rotating electric machine, A second side surface that, when the magnetic core is incorporated into the rotating electric machine, faces radially with respect to the rotation axis of the rotating electric machine, It has, The tip of the tooth is, The first region formed of the first soft magnetic material, The second region formed by the second soft magnetic material, It includes, The second soft magnetic material has a smaller average particle size than the first soft magnetic material. The aforementioned corner includes a conical corner formed by the first end face, the first side surface, and the second side surface, and the conical corner is included in the second region. Magnetic core.

2. The corner portion includes a marginal corner portion formed by the first end face and the first side surface, and the marginal corner portion is included in the second region. A magnetic core according to claim 1.

3. The core back portion is The second end face which will face the axial direction when the magnetic core is incorporated into the rotating electric machine, The third side surface which faces the circumferential direction when the magnetic core is incorporated into the rotating electric machine, It has, The core back portion is, The first region and, The aforementioned second region, It includes, The aforementioned corner portion includes a marginal corner portion formed by the second end face and the third side surface, and the marginal corner portion is included in the second region. A magnetic core according to claim 1 or claim 2.

4. The core back portion is, It has a fourth side surface that faces the radial direction when the magnetic core is incorporated into the rotating electric machine, The aforementioned corner includes a conical corner formed by the second end face, the third side surface, and the fourth side surface, and the conical corner is included in the second region. The magnetic core according to claim 3.

5. Both the first region and the second region are formed in layers, The first region and the second region are stacked along the axial direction. A magnetic core according to claim 1 or claim 2.

6. The first region is sandwiched between the second region in the axial direction. The magnetic core according to claim 5.

7. The average particle size of the second soft magnetic material is greater than 10% of the average particle size of the first soft magnetic material and less than or equal to 65%. A magnetic core according to claim 1 or claim 2.

8. A magnetic core according to claim 1 or claim 2, The coil wound around the main body of the teeth, Equipped with, Magnetic core with coil.

9. A magnetic core comprising the magnetic core described in claim 1 or claim 2, Rotating electrical machinery.

10. A method for manufacturing a magnetic core according to claim 1 or claim 2, An injection step in which a first soft magnetic powder and a second soft magnetic powder with different average particle sizes are injected into a mold such that they are stacked in layers within the mold, Following the injection step, a compression molding step is performed in which the first soft magnetic powder and the second soft magnetic powder are compressed and molded along the direction in which they are stacked. Equipped with, A method for manufacturing a magnetic core.