JP7298378B2 - Method for manufacturing magnetic core - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing a magnetic core for use in, for example, electric motors and generators.

2. Description of the Related Art Conventionally, the method described in Patent Document 1 is known as a method for manufacturing a magnetic core used in electric motors and generators. The manufacturing method described in Patent Document 1 includes a step of forming a punched member having a through hole or a crimped portion from a strip-shaped electromagnetic steel sheet wound into a coil, and a step of forming a through hole while laminating a plurality of punched members. and forming a laminated core by fastening a plurality of punched members via the crimping portion. The caulking portion is composed of a concave portion formed on the front side of the punched member and a convex portion formed on the back side of the punched member. In the crimping portion described in FIG. 3 of Patent Document 1, the convex portion has a mountain shape as a whole, and includes a top portion with a large amount of protrusion and skirt portions located on both sides of the top portion. The convex portion of one punching member fits into the concave portion or through hole of another punching member adjacent to the back side of the one punching member.

JP 2019-110644 A

It is known that a laminated body used as a magnetic core increases iron loss such as eddy current loss when the electrical insulation resistance between steel sheets decreases. A typical electromagnetic steel sheet has an insulating coating applied to the surface to prevent electrical conduction due to surface contact between laminated surfaces of core plates obtained by punching the electromagnetic steel sheet. Also, conduction between the side surface of the protrusion and the inner surface of the recess or the through hole in the caulked portion is suppressed by a film produced by bluing, for example. Bluing is a process of forming a film of triiron tetroxide (Fe ₃ O ₄ ), also called black rust, in order to prevent the generation of red rust (Fe ₂ O ₃ ) that causes corrosion of steel materials.

In addition, since the thickness of the laminate used as the magnetic core tends to fluctuate in the lamination direction due to the accumulation of small gaps between the core plates, a large load is applied in the lamination direction to reduce the gap between the core plates. A compression process may be performed. In this case, if the side surface of the projection and the inner surface of the recess or the through-hole in the caulked portion are fixed by black rust, for example, there is a possibility that a sufficient compression effect in the stacking direction cannot be obtained by applying a load.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method of manufacturing a magnetic core capable of suppressing sticking of concave portions and convex portions for mutually connecting a plurality of laminated core plates.

In order to achieve the above object, the present invention provides a method for manufacturing a magnetic core by stacking a plurality of core plates, comprising: punching a steel plate to form the plurality of core plates; A pressing step of forming recesses and protrusions for mutually connecting the core plates, a lamination step of stacking the plurality of core plates and fitting the protrusions into the recesses to form a laminate, and the laminate A heat treatment step of heat-treating and a vibrating step of vibrating the heat-treated laminated body , wherein the heat treatment forms a black rust layer between the inner surface of the recess and the end surface of the protrusion. Provided is a method for manufacturing a magnetic core, including a bluing treatment step, in which the laminate is vibrated in the stacking direction in the vibrating step to generate gaps due to cracks in the black rust layer.

According to the method for manufacturing a magnetic core according to the present invention, it is possible to suppress adhesion of concave portions and convex portions for mutually connecting a plurality of laminated core plates.

1 is a configuration diagram showing a rotating electric machine manufactured using a manufacturing method according to an embodiment of the present invention, where (a) is a state viewed from the axial direction, and (b) is taken along line AA of (a). A cross-section is shown, respectively. FIG. 4 is a flow chart showing the manufacturing procedure of the stator core; FIG. 4 is an explanatory view showing a stacking step of stacking a plurality of core plates; (a) is a perspective view showing a crimped portion seen from the back surface of a core plate, and (b) is a perspective view showing a fitting state of the crimped portions of a plurality of core plates. (a) is a schematic configuration diagram of a heat treatment apparatus for a heat treatment step, and (b) is a schematic diagram showing a configuration example of a brewing station. Shows the laminate after heat treatment, (a) is a perspective view showing the end of the back side of the core plate in a cross section along the inner surface of the recess, (b) is a cross section of the laminate along line BB in (a). It is a diagram. FIG. 4 shows a laminate in a vibrating step, where (a) is a top view and (b) is a cross-sectional view taken along line CC of (a). (a), (b) is explanatory drawing which shows typically an example of the state of the black rust layer before and behind a vibration excitation process. FIG. 4 is a cross-sectional view showing a laminate and a pressurizing device in a pressurizing step together with a fixture; FIG. 4 is a cross-sectional view showing a laminate, a pressing device, and a measuring instrument in a measuring process together with fixtures;

[Embodiment]
An embodiment of the present invention will be described with reference to FIGS. 1 to 10. FIG. It should be noted that the embodiment described below is shown as a preferred specific example for carrying out the present invention, and there are portions that specifically illustrate various technically preferable technical matters. , the technical scope of the present invention is not limited to this specific embodiment.

(Configuration of rotating electric machine)
FIG. 1 is a configuration diagram showing a rotating electrical machine manufactured using a manufacturing method according to an embodiment of the present invention, where (a) is the state viewed from the axial direction, and (b) is A in (a). A cross-section along line -A is shown, respectively.

This rotating electric machine 100 has a stator 1 and a rotor 2 . The stator 1 is non-rotatably fixed to a housing (not shown). A shaft 10 is inserted through the center of the rotor 2 and rotates integrally with the shaft 10 . The rotating electric machine 100 is mounted on, for example, an electric vehicle or a so-called hybrid vehicle as a motor that generates driving force, as a generator that converts the rotational force of the shaft 10 into electrical energy, or as a motor generator that has both functions. be.

The stator 1 includes a stator core 11 and multiple coils 12 . The stator core 11 integrally includes a cylindrical base portion 111, a plurality of teeth 112 protruding radially inward from the base portion 111, and a plurality of fixed portions 113 protruding radially outward from the base portion 111. have. In the illustrated example of FIG. 1 , the stator core 11 has 15 teeth 112 and the coil 12 is wound around each tooth 112 . The fixed portion 113 is formed with a bolt insertion hole 113a through which a bolt for fixing the stator core 11 to the housing is inserted.

The rotor 2 has a rotor core 21 and a plurality of magnets 22 held by the rotor core 21 . The rotor core 21 has a central hole 210 through which the shaft 10 is inserted, a plurality of accommodation holes 211 each accommodating a plurality of magnets 22 (shown in FIG. 1(b)), and a coolant for cooling the magnets 22. A plurality of cooling holes 212 are formed for cooling. A center hole 210 , a plurality of housing holes 211 , and a plurality of cooling holes 212 axially penetrate the rotor core 21 . Also, the rotor core 21 has a pair of protrusions 21a that are fitted into the pair of key grooves 10a of the shaft 10, respectively, so that relative rotation with the rotor core 21 is restricted. The magnet 22 has a square prism shape with a rectangular cross section perpendicular to the longitudinal direction, and is fixed to the rotor core 21 by a resin 23 filling an accommodation hole 211 .

The stator core 11 and rotor core 21 are both magnetic cores that serve as magnetic paths for the magnetic flux generated by the plurality of coils 12 and magnets 22, and are configured by laminating a plurality of thin plates (core plates) formed by punching electromagnetic steel plates. It is The stator core 11 is formed by laminating a plurality of core plates 3 , and the rotor core 21 is formed by laminating a plurality of core plates 4 . The thickness of one core plate 3, 4 is, for example, 0.25 mm.

A plurality of core plates 3 of stator core 11 are connected to each other by a plurality of crimped portions 31 formed in each core plate 3 . Similarly, a plurality of core plates 4 of rotor core 21 are interconnected by a plurality of caulking portions 41 formed in each core plate 4 . In the illustrated example of FIG. 1( a ), one core plate 3 is provided with five crimping portions 31 , and one core plate 4 is provided with five crimping portions 41 . A method for manufacturing the stator core 11 will be described in detail below, but the rotor core 21 can also be manufactured by a similar manufacturing method.

(Manufacturing method of stator core)

FIG. 2 is a flowchart showing the manufacturing procedure of the stator core 11. As shown in FIG. The method of manufacturing the stator core 11 includes a crimping forming step S1 in which a plurality of crimped portions 41 are formed by pressing an electromagnetic steel sheet as a raw material, and a punching step in which the core plate 3 is formed by punching the electromagnetic steel sheet by the same press working. S2, a stacking step S3 of stacking the obtained core plates 3 to form a laminate, a heat treatment step S4 of heat-treating this laminate, a vibration step S5 of vibrating the laminate after heat treatment, and vibration. It has a pressurizing step S6 for pressurizing the subsequent laminate in the stacking direction, and a measuring step S7 for measuring the thickness of the laminate after pressurization.

Note that the core plate 3 may be punched out of the electromagnetic steel sheet and a plurality of crimped portions 31 may be formed by one press working. That is, the crimping step S1 and the punching step S2 may be performed simultaneously. Alternatively, the crimping step S1 may be performed after the punching step S2. In other words, the caulking forming step S1 and the punching step S2 form a plurality of core plates 3 by punching an electromagnetic steel sheet, and form recesses 310 and protrusions 311 for connecting the plurality of core plates 3 to each other. It is a press process to do.

As the electrical steel sheet, it is possible to use a full-processed material that obtains predetermined magnetic properties by finishing annealing in advance at a steel manufacturer, etc., or a semi-processed material that obtains predetermined magnetic properties by performing annealing for strain relief after punching. may be used. In this embodiment, a case where a semi-processed material is used will be described. The semi-processed material has a smaller crystal size than the fully-processed material, and since the core loss increases as it is, it is necessary to grow crystals by an annealing treatment to be described later. Semi-processed material is generally less expensive than fully processed material.

FIG. 3 is an explanatory view showing a stacking step S3 for stacking a plurality of core plates 3 formed by the punching step S2. FIG. 4(a) is a perspective view showing the caulked portion 31 seen from the back surface 3b of the core plate 3, and FIG. It is a perspective view showing. In FIG. 4B, the front surface 3a side of the plurality of core plates 3 is illustrated.

The caulking portion 31 is formed so as to protrude from the front surface 3a side of the core plate 3 toward the back surface 3b side. In the present embodiment, the convex portion 311 has a trapezoidal shape, and is formed by a pair of ridges 313 whose protrusion amount from the back surface 3b gradually decreases as the protrusion amount from the back surface 3b increases and the protrusion amount from the back surface 3b gradually decreases as the distance from the top portion 312 increases. A part 311 is configured. Further, in the present embodiment, the top portion 312 has a rectangular shape parallel to the back surface 3b, and a pair of edge portions 313 are connected to both ends in the long side direction.

In addition, the shape of the convex portion 311 is not limited to the trapezoidal shape, and may be, for example, a triangular shape. In this case, a convex portion is formed by a pair of inclined portions inclined in opposite directions with respect to the back surface 3b. In the present embodiment, the amount of projection of the top portion 312 is greater than the thickness of the core plate 3, and the entire top portion 312 projects from the back surface 3b in the thickness direction of the core plate 3. may be smaller than the thickness of the core plate 3 .

When connecting a plurality of core plates 3, the protrusions 311 of one core plate 3 are fitted into the recesses 310 of the other core plate 3 facing the back surface 3b. The number of laminated core plates 3 is set according to the required thickness of the stator core 11 in the lamination direction. In this embodiment, several tens of core plates 3 are connected by fitting recesses 310 and protrusions 311 to form one block, a plurality of blocks are stacked in the stacking direction, and these blocks are fixed together by welding. are doing.

The laminate obtained in the lamination step S3 is subjected to the heat treatment step S4. The heat treatment step S4 includes a plurality of sub-steps as shown in FIG. In the present embodiment, these sub-processes consist of a deoiling treatment step S41, an annealing treatment step S42, a first cooling treatment step S43, a bluing treatment step S44, and a second cooling treatment step S45. Next, this heat treatment step S4 will be described in detail.

FIG. 5(a) is a schematic configuration diagram of the heat treatment apparatus 5 for the heat treatment step S4. The heat treatment apparatus 5 includes a loading station 50 into which the laminate 6 obtained in the stacking step S3 is loaded, a deoiling station 51 for deoiling, an annealing station 52 for annealing, and a first cooling station for first cooling. A cooling station 53, a brewing station 54 for performing a bluing process, a second cooling station 55 for performing a second cooling process, and an unloading station 56 for unloading the heat-treated laminate 6, and the stations 50 to 56 are partitioned. It has partitions 571 to 576 .

The deoiling station 51 heats the laminate 6 to a predetermined deoiling temperature to evaporate the oil adhering to the core plate 3 . The oil is applied to the magnetic steel sheet in advance in order to facilitate the punching of the core plate 3 from the magnetic steel sheet. The deoiling temperature is, for example, 300-400°C.

The annealing station 52 heats and anneals the laminate 6 . In this annealing treatment, the laminate 6 is heated to a predetermined annealing temperature and maintained in that state for a predetermined time. The annealing temperature differs depending on whether the full-processed material is used or the semi-processed material. As described above, since the semi-processed material is used in the present embodiment, annealing is performed at 820 to 850° C. to remove strain and increase the size of metal crystals. At the first cooling station 53, the laminate 6 is cooled from the annealing temperature to a bluing temperature suitable for bluing (eg 450° C.). Also, in the second cooling station 55, the brewed laminate 6 is cooled to room temperature.

FIG. 5B is a schematic diagram showing a configuration example of the brewing station 54. As shown in FIG. The brewing station 54 has a heater 541 that sets the temperature of the furnace 540 in which the laminate 6 is arranged as the brewing temperature, and a nozzle 542 that supplies the atmospheric gas G into the furnace 540 . As atmosphere gas G, nitrogen gas (N ₂ ), HN mixed gas (N ₂ +H ₂ ), endothermic modified gas (RX gas), exothermic modified gas (DX gas), etc. can be used. N) is the main component, and DX gas (exothermic modified gas) containing hydrogen (H ₂ ), carbon monoxide (CO), and moisture is used.

By this bluing, cross sections of the inner and outer peripheral surfaces of the core plate 3 formed in the punching step S2, end faces 311a (see FIG. 4A) of the convex portions 311 formed in the caulking forming step S1, and A coating of triiron tetraoxide (Fe ₃ O ₄ ), also called black rust, is formed on the inner surface 310a (see FIG. 4B) of the recess 310 . The generation of the triiron tetraoxide film can prevent the subsequent generation of red rust (Fe ₂ O ₃ ).

FIG. 6 shows the laminated body 6 after the heat treatment, (a) is a perspective view showing the end portion of the core plate 3 on the back surface 3b side in a cross section along the inner surface 310a of the recess 310, and (b) is a cross section of (a). 3 is a cross-sectional view of the laminate 6 taken along line BB. FIG. As shown in FIG. 6A, the core plate 3 at one end of the laminate 6 is formed with a fitting hole 320 into which the convex portion 311 is fitted instead of the concave portion 310 and the convex portion 311. . The fitting hole 320 is a square hole penetrating between the front surface 3a and the rear surface 3b.

As shown in an enlarged view in FIG. 6B, the front surface 3a and the back surface 3b of the core plate 3 are coated with an electrically insulating resin coating. The insulating coat layer 62 formed on the back surface 3b is illustrated. Conduction between the front surface 3a and the rear surface 3b of the pair of core plates 3 arranged in the stacking direction is interrupted by insulating coat layers 61 and 62. As shown in FIG.

6B shows a black rust layer 63 formed by triiron tetraoxide between the end surface 311a of the projection 311 and the inner surface 310a of the recess 310. FIG. Triiron tetraoxide has a conductivity about 1/400 that of iron, but it has a conductivity that is about 10 ⁶ times that of red rust. In addition, the electric resistance of the black rust layer 63 may decrease due to mixing of the inorganic components of the insulating coat layers 61 and 62 melted by heat. Therefore, in order to suppress the iron loss, it is desirable to release the adhesion of the black rust layer 63 between the end surface 311a of the projection 311 and the inner surface 310a of the recess 310 .

In the present embodiment, the fixing by the black rust layer 63 between the end surface 311a of the convex portion 311 and the inner surface 310a of the concave portion 310 is released mainly by the vibrating step S5. Further, in the present embodiment, after the fixing by the black rust layer 63 is released in the vibrating step S5, the pressure step S6 is further performed to bring the plurality of core plates 3 into close contact with each other, thereby increasing the lamination thickness of the laminate 6. is kept within a specified tolerance range. That is, by performing the pressurizing step S6 after the fixing by the black rust layer 63 is released by the vibrating step S5, the pressurizing effect can be easily obtained. In addition, the pressing step S6 makes it possible to more reliably release the adhesion of the black rust layer 63 .

The vibrating step S5, the pressing step S6, and the measuring step S7 will be described below with reference to FIGS. 7 to 10. FIG. Note that the pressure step S6 may be omitted, and the measurement step S7 may be performed after the vibration step S5. In the following description, "upper" and "lower" refer to vertical directions.

FIG. 7 shows the laminate 6 in the vibrating step S5, where (a) is a top view and (b) is a sectional view taken along line CC of (a). The vibrating step S5, the pressing step S6, and the measuring step S7 are performed while the laminate 6 is fixed to the fixture 7. FIG. FIG. 7A shows the fixture 7 together with the laminated body 6, and FIG.

The fixture 7 includes a base plate 71 , a mounting plate 72 arranged above the base plate 71 , bolts 73 screwed into the base plate 71 , and a plurality of horizontal movable bolts with respect to the base plate 71 . It has a moving plate 74 and a pressing plate 75 that presses the plurality of moving plates 74 toward the stack 6 by the axial force of the bolts 73 . The vibrating device 8 includes a body portion 81 arranged below the base plate 71 and a plurality of shafts 82 projecting upward from the body portion 81 . In the present embodiment, the vibrating device 8 is an ultrasonic vibrator that ultrasonically vibrates a plurality of shafts 82 . The number of shafts 82 is preferably three or more, for example four to six.

A bolt hole 710 is formed in the center of the base plate 71 . The base plate 71 also has a plurality of guide grooves 711 for guiding the plurality of moving plates 74 so as to be radially movable around the bolt holes 710, and a plurality of insertion holes 712 for inserting the shaft 82 of the vibrating device 8. is formed. The stack 6 is placed on the upper surface 72 a of the mounting plate 72 , and the lower surface 72 b faces the upper surface 71 a of the base plate 71 . In the vibrating step S<b>5 , the mounting plate 72 is supported by the shaft 82 of the vibrating device 8 , and a gap is formed between the lower surface 72 b of the mounting plate 72 and the upper surface 71 a of the base plate 71 .

The bolt 73 integrally has a head portion 731 , a shaft portion 732 and a male threaded portion 733 , and the male threaded portion 733 is screwed into the bolt hole 710 of the base plate 71 . The head 731 is in contact with the upper surface 75 a of the pressing plate 75 and presses the pressing plate 75 toward the base plate 71 . The shaft portion 732 is inserted through a bolt insertion hole 750 formed in the pressing plate 75 , and the male threaded portion 733 is drawn downward from the bolt insertion hole 750 .

The plurality of moving plates 74 have contact surfaces 74 a that contact the inner peripheral surface 6 a of the laminate 6 and inclined surfaces 74 b that contact the pressing plate 75 . The contact surface 74a is a surface perpendicular to the horizontal direction. The inclined surface 74b is inclined such that the distance from the bolt 73 increases toward the upper end. The pressing plate 75 has a pressing surface 75b that contacts the inclined surfaces 74b of the plurality of moving plates 74, and the axial force of the bolts 73 that press the pressing plate 75 toward the base plate 71 is applied to the plurality of moving plates. 74, the pressure is converted into a pressing force that presses the inner peripheral surface 6a of the laminate 6 in the horizontal direction.

By being pressed by the plurality of moving plates 74, the laminated body 6 is prevented from being displaced in the horizontal direction of the plurality of core plates 3, and is maintained in a state of high straightness. That is, the vibrating step S5 is performed in a state in which radial movement of the plurality of core plates 3 is restricted. In this embodiment, the pressing plate 75 has a pentagonal shape as shown in FIG. 7A, and five moving plates 74 are arranged around the pressing plate 75 corresponding to each side. , the shape of the pressing plate 75 and the number of the moving plates 74 can be appropriately changed according to the size of the laminate 6, for example.

In the vibrating device 8, the main body 81 vertically vibrates the plurality of shafts 82, and vibrates the laminate 6 placed on the placing plate 72 in the stacking direction. As a result, the fixation by the black rust layers 63 between the plurality of core plates 3 is released at least partially.

FIGS. 8A and 8B are explanatory diagrams schematically showing an example of the state of the black rust layer 63 before and after the vibrating step S5. By vibrating the laminate 6 with the vibrating device 8, a minute gap S is generated due to cracks or the like in the black rust layer 63, and the end surface 311a of the convex portion 311 and the inner surface 310a of the concave portion 310 are aligned along the stacking direction. relatively easy to move. Also, electrical conduction between the core plates 3 via the black rust layer 63 can be suppressed, and iron loss can be suppressed.

Next, the pressurizing step S6 will be described with reference to FIG. FIG. 9 is a sectional view showing the laminate 6 and the pressurizing device 91 together with the fixture 7 in the pressurizing step S6.

The pressurizing step S6 is performed with the laminate 6 fixed to the fixture 7, as in the vibrating step S5. The pressurizing device 91 is capable of generating a load of 10 tons or more, for example, and stacks the laminate 6 via an annular upper plate 77 and a disk-shaped pressure plate 78 arranged on the laminate 6 . direction. As a result, the end surfaces 311a of the protrusions 311 of the plurality of core plates 3 and the inner surfaces 310a of the recesses 310 are displaced in the stacking direction, and the fixation by the black rust layers 63 between the plurality of core plates 3 can be released more reliably. .

Further, by pressurizing the laminate 6, the plurality of core plates 3 are brought into close contact with each other and the laminate 6 is compressed in the axial direction, thereby improving the dimensional accuracy. Here, if the vibration step S5 is not performed and the pressure step S6 is performed while the end surfaces 311a of the protrusions 311 and the inner surfaces 310a of the recesses 310 of the plurality of core plates 3 are fixed by the black rust layer 63, the fixation will occur. Although there is a possibility that a sufficient pressurizing effect cannot be obtained due to the applied force acting as a resistance force, in the present embodiment, by performing the pressurizing step S6 after the vibrating step S5, the plurality of core plates 3 are brought into close contact with each other. You can definitely get the effect of

FIG. 10 is a cross-sectional view showing the laminate 6, the pressing device 92, and the measuring device 93 together with the fixture 7 in the measuring step S7. The measuring instrument 93 is an instrument for measuring the thickness of the laminate 6 in the lamination direction (axial direction), more specifically a height gauge. The measuring instrument 93 has a body portion 931 and a rod 932 axially movable with respect to the body portion 931 , and the rod 932 is inserted through an insertion hole 770 formed in the upper plate 77 . The body portion 931 is arranged above the upper plate 77 , and the tip portion of the rod 932 contacts the upper surface 72 a of the mounting plate 72 .

The measurement by the measuring device 93 is performed in a state in which the pressing device 92 presses the laminate 6 toward the mounting plate 72 via the pressure plate 78 and the upper plate 77 . The pressing load applied by the pressing device 92 is a relatively small load that is several tenths of the load generated by the pressing device 91 .

As a result of this measurement, if the lamination thickness of the laminate 6 is within a predetermined tolerance range, the laminate 6 is used as the stator core 11 and the coils 12 are wound around the plurality of teeth 112 to form the stator 1 .

(Actions and effects of the embodiment)
According to the embodiment described above, it is possible to suppress the adhesion of the concave portions 310 and the convex portions 311 that connect the plurality of laminated core plates 3 to each other, thereby suppressing the occurrence of iron loss. The dimensional accuracy of the accumulated pressure can be improved. Further, since the vibrating step S5 and the pressing step S6 are performed while the laminate 6 is fixed to the fixture 7, displacement of the plurality of core plates 3 is suppressed, and the straightness of the laminate 6 can be improved. can.

(Appendix)
As described above, the present invention has been described based on the embodiments, but the embodiments do not limit the invention according to the scope of claims. Also, it should be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

Further, the present invention can be modified appropriately without departing from the gist of the invention, and can be applied to manufacture of magnetic cores of devices other than the rotary electric machine 100, for example.

DESCRIPTION OF SYMBOLS 100... Rotary electric machine 1... Stator 2... Rotors 3 and 4... Core plate 6... Laminated body 11... Stator core (magnetic core)
21 ... Rotor core (magnetic core)

Claims (3)

A method for manufacturing a magnetic core formed by laminating a plurality of core plates,
a pressing step of punching a steel plate to form the plurality of core plates and forming recesses and projections for interconnecting the plurality of core plates;
a stacking step of stacking the plurality of core plates and fitting the protrusions into the recesses to form a stack;
a heat treatment step of heat-treating the laminate;
and a vibrating step of vibrating the heat-treated laminate ,
The heat treatment includes a bluing treatment step of forming a black rust layer between the inner surface of the recess and the end surface of the protrusion,
In the vibrating step, the laminate is vibrated in the lamination direction to generate cracks in the black rust layer to form gaps.
A method for manufacturing a magnetic core. The vibrating step is performed in a state in which radial movement of the core plate is restricted.
The manufacturing method of the magnetic core according to claim 1 . After the heat treatment step and the vibrating step, further comprising a pressurization step of pressurizing the laminate in the stacking direction,
The method for manufacturing a magnetic core according to claim 1 or 2 .

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