Method for manufacturing magnetic cores and methods for manufacturing coil components

Abstract

This method for producing a magnetic core comprises a step for melting a raw-material powder containing a soft magnetic metal powder and an aggregation inhibitor using laser irradiation or electron beam sweeping, and then solidifying the product, thereby fabricating a three-dimensional composite magnetic body.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a magnetic core and a method for manufacturing a coil component.

Background Art

[0002] Patent Document 1 discloses a method for manufacturing a laminated soft magnetic material using a laminated molding apparatus that includes a supply means for raw material powder and a heating means for irradiating the raw material powder with a high-energy beam to melt the raw material powder, and repeating the melting and solidification of the raw material powder in a chamber to obtain a desired three-dimensional molded object. The raw material powder is a soft magnetic powder made of an iron alloy containing at least Al, the inside of the chamber is a processing atmosphere containing nitrogen and / or oxygen, a first step of melting the soft magnetic powder with the heating means and then solidifying it to obtain a soft magnetic layer, and a second step of reheating the surface of the soft magnetic layer with the heating means in the processing atmosphere to form an insulating layer made of nitride and / or oxide on the surface of the soft magnetic layer. A method for manufacturing a laminated soft magnetic material in which the soft magnetic layer and the insulating layer are alternately laminated by alternately repeating the above steps is described.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 states that an additive manufacturing apparatus is an apparatus that performs additive manufacturing (AM) using metal powder, and may be an apparatus that performs powder bed fusion (PBF) or directed energy deposition (DED). In the PBF method, a metal powder supply system consisting of a feeder (powder supply tank) and a recoater (metal powder spreading device) is required. Similarly, in the DED method, a metal powder supply system consisting of a feeder (powder supply tank) and a powder spray nozzle is required. However, in these supply systems, problems such as powder clogging, powder spreading defects, or spray pulsation are likely to occur due to a decrease in the fluidity of the metal powder. In such cases, since a high-energy beam is irradiated onto the metal powder that is discontinuously supplied from the supply system, it is difficult to obtain the desired three-dimensional object.

[0005] One method to suppress the decrease in the fluidity of metal powder in a metal powder supply system is to prepare metal powder with high sphericity and monodispersity to reduce the likelihood of aggregation. However, obtaining metal powder with high sphericity and monodispersity requires extensive research to establish the manufacturing conditions of the metal powder using atomization methods, etc., and to adjust the particle size distribution using airflow classification, etc., making it difficult to obtain metal powder for three-dimensional metal fabrication. Examples of metal powders with high sphericity and monodispersity for three-dimensional metal fabrication that are commercially available include metal powder for mold fabrication with a composition of Fe-18Ni-5Mo-9Co-AlTi, metal powder for turbines and aircraft with a composition of Ni-20Cr-3Mo-5Nb-FeTiAl, and metal powder for artificial bones with a composition of Co-29Cr-6Mo (Reference URL: http: / / www.sanyo-steel.co.jp / product / selected / selected13.php). However, since there are very few examples of studies on three-dimensional metal fabrication using soft magnetic metal powders like those described in Patent Document 1, it is difficult to obtain soft magnetic metal powders with high sphericity and monodispersity.

[0006] Based on the above, in the method of forming a three-dimensional object using soft magnetic metal powder as described in Patent Document 1, it is necessary to improve the fluidity of the soft magnetic metal powder in the metal powder supply system.

[0007] The present invention was made to solve the above problems and aims to provide a method for manufacturing a magnetic core that can suppress a decrease in the fluidity of soft magnetic metal powder in a metal powder supply system. Furthermore, the present invention aims to provide a method for manufacturing a coil component using the above magnetic core. [Means for solving the problem]

[0008] The present invention provides a method for manufacturing a magnetic core, comprising the step of forming a three-dimensional composite magnetic material by melting a raw material powder containing soft magnetic metal powder and an aggregation inhibitor using laser irradiation or electron beam sweeping, and then solidifying it.

[0009] The method for manufacturing a coil component of the present invention comprises the steps of: manufacturing a magnetic core using the method for manufacturing a magnetic core of the present invention; and winding a coil conductor around the outer surface of the magnetic core. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for manufacturing a magnetic core that can suppress a decrease in the fluidity of soft magnetic metal powder in a metal powder supply system. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing the soft magnetic metal powder and aggregation-inhibiting particles in the raw material powder in one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing a coil component manufactured according to one embodiment of the present invention. [Figure 3] Figure 3 is an SEM image showing the inside of the magnetic core fabricated according to Example 1-1. [Modes for carrying out the invention]

[0012] The following describes the method for manufacturing a magnetic core and a coil according to the present invention. However, the present invention is not limited to the following embodiments and can be modified and applied as appropriate without altering the essence of the invention. Furthermore, a combination of two or more of the preferred configurations of the present invention described below also constitutes the present invention.

[0013] [Manufacturing method for magnetic cores] The present invention provides a method for manufacturing a magnetic core, comprising the step of forming a three-dimensional composite magnetic material by melting a raw material powder containing soft magnetic metal powder and an aggregation inhibitor using laser irradiation or electron beam sweeping, and then solidifying it.

[0014] In the method for manufacturing magnetic cores of the present invention, the aggregation of soft magnetic metal powder during the supply process can be suppressed because the raw material powder contains an aggregation inhibitor. Therefore, a decrease in the fluidity of the soft magnetic metal powder in the metal powder supply system can be suppressed.

[0015] Incidentally, in three-dimensional metal fabrication for applications such as metal parts for aircraft and automobiles, or molds for molding, studies are being conducted to improve the fluidity of the metal powder in the metal powder supply system by using metal powder with high sphericity and monodispersity. This is because internal metal defects can be a cause of fatal accidents in three-dimensional metal fabricated objects for mechanical parts. When an aggregation inhibitor is added when fabricating three-dimensional metal for mechanical parts, there is a concern that metal fracture may occur in the fabricated mechanical part, originating from the aggregation inhibitor. For this reason, three-dimensional metal fabrication with the addition of an aggregation inhibitor is considered unsuitable for mechanical parts. In contrast, when fabricating a magnetic core as in the present invention, the required mechanical strength of the magnetic core is lower than that of a mechanical part, so there is no need to consider the adverse mechanical effects caused by the aggregation inhibitor.

[0016] In the method for manufacturing a magnetic core of the present invention, after supplying raw material powder containing soft magnetic metal powder and an aggregation inhibitor onto a stage, the raw material powder on the stage may be melted using laser irradiation or electron beam scanning and then solidified to form a three-dimensional composite magnetic body. Alternatively, in the method for manufacturing a magnetic core of the present invention, simultaneously with the supply of raw material powder containing soft magnetic metal powder and an aggregation inhibitor, the raw material powder may be melted using laser irradiation or electron beam scanning and then solidified to form a three-dimensional composite magnetic body.

[0017] Note that the method for manufacturing a magnetic core of the present invention may be performed, for example, by a powder bed fusion method (PBF: powder bed fusion) or by a directed energy deposition method (DED: directed energy deposition). The PBF method is a method of manufacturing a shaped object of a desired shape by repeatedly scanning a high-energy beam (laser, electron beam, etc.) along a predetermined path to melt and then solidify the raw material powder each time a thin layer of the raw material powder (metal powder) is laid. The DED method is a method of manufacturing a shaped object of a desired shape by melting and then solidifying the raw material powder projected near the focus of a high-energy beam and scanning (moving) the melt-solidification position.

[0018] For example, in the case of the PBF method, the raw material powder is supplied by a supply system including a feeder (powder supply tank) and a recoater (metal powder spreading device). Also, in the case of the DED method, the raw material powder is supplied by a supply system including a feeder (powder supply tank) and a powder injection nozzle.

[0019] In the method for manufacturing a magnetic core of the present invention, first, raw material powder is prepared.

[0020] The raw material powder contains soft magnetic metal powder and an aggregation inhibitor. By including an aggregation inhibitor in the raw material powder, it is possible to suppress the aggregation of the soft magnetic metal powder during the process of supplying the raw material powder.

[0021] As the raw material powder, a mixed powder containing soft magnetic metal powder and a powder aggregation inhibitor may be used, or a composite powder in which a layer of aggregation inhibitor is provided on the surface of the soft magnetic metal powder may be used. For example, a composite powder in which a glass coating of aggregation inhibitor is applied to the surface of the soft magnetic metal powder may be used as the raw material powder.

[0022] When using a mixed powder containing soft magnetic metal powder and a powder agglomeration inhibitor as a raw material powder, the powder agglomeration inhibitor may be added to a supply system such as a feeder in a state where it is mixed with the soft magnetic metal powder, or the powder agglomeration inhibitor may be mixed with the soft magnetic metal powder in a supply system such as a feeder.

[0023] [Soft magnetic metal powder] The soft magnetic metal powder may be crystalline metal powder or amorphous metal powder.

[0024] Examples of crystalline metal powders include Fe-Si-based metal powder, Fe-Ni-based metal powder, Fe-Si-Al-based metal powder, Fe-Si-Cr-based metal powder, carbonyl iron powder, Fe-Co-based metal powder, and Fe-Co-V-based metal powder. The Fe-Ni-based metal powder may be permalloy magnetic powder. The Fe-Si-Al-based metal powder may be Sendust magnetic powder. The Fe-Co-based metal powder may be permendur. The crystalline metal powder may be one type or two or more types.

[0025] Examples of amorphous metal powders include Fe-Si-B-Cr amorphous alloy powders and Fe-B-Si amorphous alloy powders. The amorphous metal powder may consist of only one type or two or more types.

[0026] The soft magnetic metal powder may be a mixed metal powder containing two or more types of metals, such as crystalline metal powder and amorphous metal powder.

[0027] In particular, the soft magnetic metal powder preferably contains at least one of Cr and Ni. When the soft magnetic metal powder contains at least one of Cr and Ni, a thin oxide film, which is a passivation film, is formed on the surface of the soft magnetic metal in the three-dimensional composite magnetic material after fabrication. When a thin oxide film, which is a passivation film, is formed on the surface of the soft magnetic metal in the three-dimensional composite magnetic material after fabrication, the insulating properties of the composite magnetic material are improved.

[0028] The particle size of the soft magnetic metal powder is not particularly limited, but it is preferable that the minimum particle size of the soft magnetic metal powder is 9 μm or more and the maximum particle size is 350 μm or less. When the minimum particle size of the soft magnetic metal powder is 9 μm or more, three-dimensional composite magnetic materials can be fabricated with high precision. When the maximum particle size of the soft magnetic metal powder is 350 μm or less, the soft magnetic metal powder can be easily melted by laser irradiation or electron beam sweeping. For example, in the PBF method, when the raw material powder is melted by laser irradiation, it is preferable that the minimum particle size of the soft magnetic metal powder is 20 μm or more and the maximum particle size is 350 μm or less. In the PBF method, when the raw material powder is melted by electron beam sweeping, it is preferable that the minimum particle size of the soft magnetic metal powder is 45 μm or more and the maximum particle size is 350 μm or less. In the DED method, when the raw material powder is melted by laser irradiation, it is preferable that the minimum particle size of the soft magnetic metal powder is 45 μm or more and the maximum particle size is 350 μm or less. Note that the minimum and maximum particle sizes of the soft magnetic metal powder refer to the minimum and maximum particle sizes of the soft magnetic metal powder in the raw material powder, respectively.

[0029] The average primary particle size of the soft magnetic metal powder is not particularly limited, but is preferably between 10 μm and 300 μm. The average primary particle size of the soft magnetic metal powder refers to the volume-based median diameter (D50) determined by laser diffraction / scattering. Furthermore, the average primary particle size of the soft magnetic metal powder refers to the average primary particle size of the soft magnetic metal powder in the raw material powder.

[0030] [Agglutination inhibitors] The aggregation inhibitor should be one that prevents the aggregation of soft magnetic metal powder.

[0031] The aggregation inhibitor is preferably an aggregation-inhibiting particle having a smaller average primary particle diameter than the soft magnetic metal powder. The average primary particle diameter of the aggregation-inhibiting particle refers to the average particle diameter calculated using the BET method, i.e., the average particle diameter of the aggregation-inhibiting particle calculated from the specific surface area obtained using the BET method. If the average particle diameter of the aggregation-inhibiting particle calculated using the BET method is smaller than the median diameter (D50) of the soft magnetic metal powder, then the aggregation-inhibiting particle can be said to have a smaller average primary particle diameter than the soft magnetic metal powder. Furthermore, the average primary particle diameter of the aggregation-inhibiting particle refers to the average primary particle diameter of the aggregation-inhibiting particle in the raw material powder.

[0032] Figure 1 is a schematic diagram showing the soft magnetic metal powder and aggregation-inhibiting particles in the raw material powder in one embodiment of the present invention.

[0033] As shown in Figure 1, if the aggregation inhibitor is aggregation inhibitory particles 2 having a smaller average primary particle diameter than the soft magnetic metal powder 1, the aggregation inhibitory particles 2 will penetrate between the soft magnetic metal powders 1. The aggregation inhibitory particles 2 between the soft magnetic metal powders 1 will cling to the soft magnetic metal powders 1 due to electrostatic force. The aggregation inhibitory particles 2 clinging to the soft magnetic metal powders 1 improve the fluidity of the soft magnetic metal powders 1 through a bearing effect, thereby suppressing a decrease in the fluidity of the soft magnetic metal powders 1.

[0034] The smaller the particle size of the agglomeration-inhibiting particles, the easier they become to cling to the soft magnetic metal powder due to electrostatic forces. On the other hand, if the particle size of the agglomeration-inhibiting particles is too small, they become difficult to handle due to static electricity. Therefore, it is preferable that the average primary particle size of the agglomeration-inhibiting particles be between 5 nm and 40 nm.

[0035] The specific surface area (BET method) of the aggregation-inhibiting particles is 50 m². 2 / g or more, 400m 2 It may be less than / g. Note that the specific surface area of ​​the agglomeration-inhibiting particles refers to the specific surface area of ​​the agglomeration-inhibiting particles in the raw material powder.

[0036] The agglutination inhibitor may be an inorganic lubricant or an organic lubricant. Only one type of agglutination inhibitor may be used, or two or more types may be used in combination. A combination of an inorganic lubricant-based agglutination inhibitor and an organic lubricant-based agglutination inhibitor may also be used.

[0037] Examples of inorganic lubricants include silica (fumed silica, nanosilica, etc.), talc, or other inorganic oxides such as mica. Monodisperse nanosilica is preferred. The inorganic lubricant may be present in single-component or multi-component forms.

[0038] Examples of organic lubricants include metal soaps such as metal stearate salts (zinc stearate, calcium stearate, etc.). The organic lubricant may be a single type or two or more types.

[0039] The aggregation inhibitor is preferably made of an insulating inorganic oxide. By using an inorganic oxide with a low carbon content as the aggregation inhibitor, the generation of volatile compounds can be suppressed during the process of fabricating a three-dimensional composite magnetic material, thus facilitating the fabrication of the three-dimensional composite magnetic material. Furthermore, by using an insulating inorganic oxide as the aggregation inhibitor, insulating material can be inserted between the soft magnetic metals in the composite magnetic material after three-dimensional fabrication. This insertion of insulating material between the soft magnetic metals allows the aggregation inhibitor itself to inhibit conductivity, thereby reducing eddy current losses and magnetic losses in the composite magnetic material, and improving the DC superposition characteristics.

[0040] The aggregation-inhibiting particles are preferably silica particles with an average primary particle diameter of 5 nm or more and 40 nm or less, and more preferably fumed silica with an average primary particle diameter of 5 nm or more and 40 nm or less. The average primary particle diameter of the silica particles may be 7 nm or more and 40 nm or less. By having an average primary particle diameter of 5 nm or more and 40 nm or less for the aggregation-inhibiting particles, the decrease in the fluidity of the soft magnetic metal powder can be further suppressed, and at the same time, because the silica particles themselves are insulating, eddy current losses and magnetic losses in the composite magnetic material are reduced, and the DC superposition characteristics are improved.

[0041] In other words, the aggregation-inhibiting particles have a specific surface area (BET method) of 50 m². 2 / g or more, 400m 2 It is preferable that the silica particles be less than or equal to / g, and have a specific surface area (BET method) of 50m². 2 / g or more, 400m 2 It is more preferable that the fumed silica is less than or equal to / g.

[0042] The amount of flocculation inhibitor added relative to the total amount of soft magnetic metal powder and flocculation inhibitor is not particularly limited, but may be 0.1% by volume or more and 1.0% by volume or less, 0.1% by volume or more and 0.8% by volume or less, 0.1% by volume or more and 0.6% by volume or less, or 0.1% by volume or more and 0.5% by volume or less. If the amount of flocculation inhibitor added relative to the total amount of soft magnetic metal powder and flocculation inhibitor is 0.1% by volume or more, the decrease in the fluidity of the soft magnetic metal powder can be further suppressed.

[0043] In the raw material powder, it is preferable that at least a portion of the surface of the soft magnetic metal powder is covered with an aggregation inhibitor. For example, in Figure 1, a portion of the aggregation inhibitor particles 2, which are aggregation inhibitors, are in contact with the surface of the soft magnetic metal powder 1. When at least a portion of the aggregation inhibitor is in contact with the surface of the soft magnetic metal powder 1 in this way, it can be said that at least a portion of the surface of the soft magnetic metal powder 1 is covered with the aggregation inhibitor.

[0044] If at least a portion of the surface of the soft magnetic metal powder in the raw material powder is covered with an aggregation inhibitor, the aggregation inhibitor will be scattered between the soft magnetic metals in the composite magnetic material after three-dimensional fabrication. Therefore, if the aggregation inhibitor is an insulator, the insulator will be scattered between the soft magnetic metals in the composite magnetic material, further reducing eddy current losses and magnetic losses in the composite magnetic material, and further improving the DC superposition characteristics.

[0045] [Insulating materials] The raw material powder preferably further contains an insulating material.

[0046] If the raw material powder contains insulating material, insulators originating from the insulating material will be scattered throughout the composite magnetic material after three-dimensional fabrication. As a result, eddy current losses and magnetic losses in the composite magnetic material are reduced, and the DC superposition characteristics are improved.

[0047] In the raw material powder, an insulating layer containing an insulating material may be provided on the surface of the soft magnetic metal powder. When an insulating layer containing an insulating material is provided on the surface of the soft magnetic metal powder, the insulating layer melts together with the soft magnetic metal powder during the fabrication of the composite magnetic material, making it easier to produce a composite magnetic material in which the insulating material surrounds the soft magnetic metal. As a result, eddy current losses and magnetic losses in the composite magnetic material are reduced, and the DC superposition characteristics are improved.

[0048] For example, an insulating material may be incorporated into the raw material powder by providing an insulating layer containing an insulating material mainly composed of P or Si on the surface of a soft magnetic metal powder such as a crystalline metal powder or an amorphous metal powder. Examples of insulating materials mainly composed of P or Si include fused silica, phosphate-based glass, borosilicate glass, and silicate glass.

[0049] Alternatively, an insulating layer containing an insulating material such as alumina or ferrite (Ni-Zn ferrite, Mn-Zn ferrite, or magnetite, etc.) may be provided on the surface of a soft magnetic metal powder, such as a crystalline metal powder or amorphous metal powder, thereby incorporating an insulating material into the raw material powder.

[0050] Both soft magnetic metal powders with an insulating layer containing insulating material on their surface and soft magnetic metal powders without an insulating layer containing insulating material on their surface may be used in combination. In other words, the raw material powder may contain both soft magnetic metal powders with an insulating layer containing insulating material on their surface and soft magnetic metal powders without an insulating layer containing insulating material on their surface.

[0051] The insulating material may be added to the raw material powder as a separate powder from the soft magnetic metal powder.

[0052] When an insulating material is added as a separate powder from the soft magnetic metal powder, examples of insulating materials in powder form include fused silica, phosphate-based glass, borosilicate glass, silicate glass, alumina, and ferrite (such as Ni-Zn ferrite, Mn-Zn ferrite, or magnetite).

[0053] The insulating material is preferably a ceramic powder with silicon dioxide as the base material. When the insulating material is a ceramic powder with silicon dioxide as the base material, the ceramic powder separates the magnetic metal portion in the composite magnetic material, preventing large eddy currents from flowing, and a magnetic flux gap can be created in the composite magnetic material. As a result, the magnetic loss of the composite magnetic material is reduced and the DC superposition characteristics are improved. Therefore, when the composite magnetic material is used as the core of a coil, the eddy current loss and magnetic loss in the composite magnetic material are further reduced, and the DC superposition characteristics are further improved.

[0054] Examples of ceramic powders using silicon dioxide as a base material include ceramic powders whose main components are fused silica, borosilicate glass, and silicate glass.

[0055] When an insulating material is added as a separate powder from the soft magnetic metal powder, the average primary particle diameter of the insulating material is not particularly limited, but may be between 0.1 μm and 10 μm. The average primary particle diameter of the insulating material refers to the volume-based median diameter (D50) determined by laser diffraction / scattering. Furthermore, the average primary particle diameter of the insulating material refers to the average primary particle diameter of the insulating material in the raw material powder.

[0056] The amount of insulating material added to the total amount of soft magnetic metal powder, agglomeration inhibitor, and insulating material may be between 1.0 volume% and 30.0 volume%. When the amount of insulating material added to the total amount of soft magnetic metal powder, agglomeration inhibitor, and insulating material is 1.0 volume% or more, the amount of insulating material in the composite magnetic material can be increased, further reducing eddy current losses and magnetic losses in the composite magnetic material, and further improving the DC superposition characteristics. When the amount of insulating material added to the total amount of soft magnetic metal powder, agglomeration inhibitor, and insulating material is 30.0 volume% or less, the raw material powders are more easily melted and bonded by laser irradiation or electron beam sweeping, allowing for the successful fabrication of a three-dimensional composite magnetic material.

[0057] In the method for manufacturing a magnetic core of the present invention, a three-dimensional composite magnetic material is fabricated by melting the above raw material powder using laser irradiation or electron beam sweeping, and then solidifying it.

[0058] The atmosphere used when fabricating a composite magnetic material is not particularly limited, but it is preferable to fabricate the composite magnetic material in a low-oxygen atmosphere such as a nitrogen atmosphere. Fabricating the composite magnetic material in a low-oxygen atmosphere prevents oxidation of the soft magnetic metal powder when the raw material powder is melted, which can prevent the formation of a magnetic core with the desired magnetic properties. Furthermore, by adjusting the oxygen concentration in the atmosphere when fabricating the composite magnetic material to a low level, an oxide layer can be formed at the metal interface (the interface formed when the soft magnetic metal powders fuse together), thereby forming an insulating layer, which contributes to reducing magnetic loss and improving DC superposition. For example, as described above, when fabricating a composite magnetic material using soft magnetic metal powder containing at least one of Cr and Ni, if the oxygen concentration in the atmosphere when fabricating the composite magnetic material is adjusted to a low level, a passivation film, which is an oxide layer, will be formed on the three-dimensional composite magnetic material after fabrication.

[0059] In this invention, a three-dimensional composite magnetic material of a desired shape can be fabricated by moving the irradiation position of a laser or electron beam along a desired trajectory. The shape of the composite magnetic material fabricated in the fabrication process is not particularly limited, but a ring-shaped composite magnetic material may be fabricated in the fabrication process. Alternatively, a rod-shaped, cylindrical, or rectangular parallelepiped-shaped composite magnetic material may be fabricated in the fabrication process.

[0060] By the way, in the method for manufacturing a laminated soft magnetic material described in Patent Document 1, the material is fabricated by alternately stacking soft magnetic layers and insulating layers obtained by oxidizing the soft magnetic layers. Therefore, a ring-shaped magnetic core with insulating layers in a direction that interrupts eddy currents cannot be fabricated. For this reason, it is necessary to either bend the obtained laminated soft magnetic material into a ring shape to create a ring-shaped magnetic core, or to cut out and bond four laminated soft magnetic materials together to create a ring-shaped magnetic core. Furthermore, at the joint portion of the fabricated ring-shaped magnetic core, the magnetic material or insulator will be perpendicular to each other, causing magnetic flux interruption to occur at that point.

[0061] However, in the method for manufacturing a magnetic core of the present invention, it is not necessary to fabricate the material by alternately stacking soft magnetic layers and insulating layers. Therefore, the composite magnetic material fabricated in a ring shape can be used as is as a ring-shaped magnetic core.

[0062] The present invention's method for manufacturing magnetic cores makes it possible to manufacture magnetic cores without connection points between them. Magnetic cores with this structure have excellent magnetic properties because they lack magnetic gaps. The present invention's method for manufacturing magnetic cores makes it easy to produce ring-shaped magnetic cores without magnetic gaps in the circumferential direction of the ring. Therefore, it is possible to produce ring-shaped magnetic cores with excellent magnetic properties because there is no leakage flux from magnetic gaps.

[0063] [Manufacturing method for coil components] The method for manufacturing a coil component of the present invention comprises the steps of manufacturing a magnetic core using the method for manufacturing a magnetic core of the present invention, and winding a coil conductor around the outer surface of the magnetic core.

[0064] The present invention's method for manufacturing magnetic cores allows for the production of magnetic cores with high resistance and high magnetic properties in any shape and size. Therefore, the present invention's method for manufacturing coil components eliminates the need for a molding process of the magnetic core using an ultra-high pressure press molding machine and a dedicated mold. Consequently, the present invention's method for manufacturing coil components allows for the production of coil components in a short time and at low cost.

[0065] Figure 2 is a schematic diagram showing a coil component manufactured according to one embodiment of the present invention.

[0066] In the coil component 10, a coil conductor 12 is wound around a magnetic core 11 manufactured by the magnetic core manufacturing method of the present invention.

[0067] In Figure 2, the magnetic core 11 is ring-shaped. The shape of the magnetic core 11 is not particularly limited and may be, for example, rod-shaped, cylindrical, or rectangular parallelepiped-shaped.

[0068] In Figure 2, two coil conductors 12 are wound around the magnetic core 11. It is sufficient for one or more coil conductors 12 to be wound around the magnetic core 11. Furthermore, the number of turns of the coil conductors 12 around the magnetic core 11 is not particularly limited. [Examples]

[0069] The following are examples that more specifically disclose the method for manufacturing the magnetic core of the present invention. However, the present invention is not limited to these examples.

[0070] <Example 1> As shown in Table 1 below, a raw material powder was prepared by mixing soft magnetic metal powder, an aggregation inhibitor, and an insulating material.

[0071] The fumed silica used as an agglomeration inhibitor consisted of agglomeration-inhibiting particles, which were added in an amount of 0.2% by volume relative to the volume of the raw material powder.

[0072] The fused silica used as an insulating material was added in an amount of 1.3% by volume relative to the volume of the raw material powder.

[0073] Furthermore, when using phosphate-based glass as an insulating material, an insulating layer of phosphate-based glass with a thickness of approximately 15 nm was provided on the surface of the soft magnetic metal powder.

[0074] The prepared raw material powder was fed into the feeder (powder supply tank) of a DED-type metal 3D printer, LAMDA200 [manufactured by Nidec Machine Tools Corporation]. Under a nitrogen gas flow atmosphere, the raw material powder was melted using laser irradiation and then solidified to create a ring-shaped magnetic core on a SUS steel plate. The outer diameter of the ring-shaped magnetic core was 16 mm, and the inner diameter was 10 mm.

[0075] Laser irradiation was performed under the following conditions: initial laser power of 200W or more and 1200W or less, scanning speed of 800mm / min, and spot diameter of 2mm.

[0076] [Table 1]

[0077] The fluidity of the raw material powder during the manufacturing process of the magnetic core described above was evaluated. The evaluation criteria were as follows: ○ (Good): No aggregation of raw material powder was visually observed in the feeder of the metal 3D printer. × (Defective): Aggregation of raw material powder was visually observed in the feeder of the metal 3D printer.

[0078] In Comparative Examples 1-1 to 1-3, where the raw material powder did not contain an agglomeration inhibitor, agglomeration of the raw material powder was visually observed in the feeder. In Comparative Examples 1-1 to 1-3, clogging of the raw material powder occurred in the feeder during the manufacturing process of the magnetic core, making it impossible to produce the magnetic core.

[0079] In Examples 1-1 to 1-4, where the raw material powder contained an aggregation inhibitor, no aggregation of the raw material powder was observed in the feeder. In Examples 1-1 to 1-4, the decrease in the fluidity of the soft magnetic metal powder in the metal powder supply system was suppressed, making it possible to fabricate magnetic cores of the desired shape.

[0080] The ring-shaped magnetic core fabricated according to Example 1-1 was cut from a SUS steel plate by electrical discharge machining. The inside of the extracted ring-shaped magnetic core was observed using a scanning electron microscope (SEM).

[0081] Figure 3 is an SEM image showing the inside of the magnetic core fabricated according to Example 1-1.

[0082] In the SEM image in Figure 3, relatively small metal particles with a particle size of about several tens of micrometers were observed inside the fabricated magnetic core. In this invention, the particle size of the metal particles inside the fabricated magnetic core can be controlled by adjusting conditions such as the output and scanning speed of the laser irradiation or electron beam sweep.

[0083] <Example 2> A ring-shaped magnetic core was fabricated under the same conditions as in Example 1, except that the composition of the raw material powder was changed as shown in Table 2.

[0084] [Table 2]

[0085] Similar to Example 1, the fluidity of the raw material powder during the manufacturing process of the magnetic core was evaluated.

[0086] In Examples 2-1 to 2-5, where the amount of agglomeration inhibitor added relative to the total amount of soft magnetic metal powder and agglomeration inhibitor was between 0.1% and 1.0% by volume, no agglomeration of the raw material powder was observed in the feeder. In Examples 2-1 to 2-5, the decrease in the fluidity of the soft magnetic metal powder in the metal powder supply system was suppressed, making it possible to produce magnetic cores of the desired shape.

[0087] <Example 3> A ring-shaped magnetic core was fabricated under the same conditions as in Example 1, except that the composition of the raw material powder was changed as shown in Table 3. The fused silica powder used had a D50 diameter of 0.59 μm.

[0088] [Table 3]

[0089] Similar to Example 1, the fluidity of the raw material powder during the manufacturing process of the magnetic core was evaluated.

[0090] In Examples 3-1 to 3-4, where the amount of insulating material added relative to the total amount of soft magnetic metal powder, agglomeration inhibitor, and insulating material was 1.3% by volume or 5.0% by volume, no agglomeration of the raw material powder was observed in the feeder. In Examples 3-1 to 3-4, the decrease in the fluidity of the soft magnetic metal powder in the metal powder supply system was suppressed, making it possible to produce magnetic cores of the desired shape. Furthermore, in Examples 3-1 to 3-4, where the amount of agglomeration inhibitor added relative to the total amount of soft magnetic metal powder and agglomeration inhibitor was between 0.1% by volume and 1.0% by volume, the decrease in the fluidity of the soft magnetic metal powder in the metal powder supply system was suppressed.

[0091] Next, we will consider the required amount of aggregation inhibitor with specific examples. For example, as an example containing fused silica, which has a larger specific surface area than soft magnetic metal powder, we consider a raw material powder that contains 95% by volume of soft magnetic metal powder and 5% by volume of fused silica relative to the total amount of soft magnetic metal powder and fused silica used in this example. In this case, the total specific surface area of ​​the soft magnetic metal powder and fused silica is 0.12 m². 2 It can be converted to / g. In the raw material powder, fumed silica is added at 0.5 volume% (specific surface area 0.29 m²) relative to the total amount of soft magnetic metal powder and fumed silica. 2 By including fumed silica ( / g), the fumed silica can cover the surface of the soft magnetic metal powder. Here, it is thought that if the surface area of ​​the fumed silica is equivalent to the specific surface area of ​​the soft magnetic metal powder and fused silica, the decrease in the fluidity of the soft magnetic metal powder can be suppressed. Therefore, it is thought that if the amount of fumed silica is contained up to about 0.5 volume percent relative to the total amount of soft magnetic metal powder and fumed silica, even if it is not contained above, a sufficient effect in suppressing the decrease in the fluidity of the soft magnetic metal powder can be expected. [Explanation of symbols]

[0092] 1 Soft magnetic metal powder 2. Aggregation-inhibiting particles 10 coil components 11 Magnetic Cores 12 Coil conductors

Claims

1. A method for manufacturing a magnetic core, characterized by comprising a step of forming a three-dimensional composite magnetic body by melting a raw material powder, which includes a soft magnetic metal powder, an agglomeration inhibitor, and an insulating material, wherein the agglomeration inhibitor is fumed silica and the insulating material is fused silica, phosphate-based glass, borosilicate-based glass, silicate glass, alumina, or ferrite, using laser irradiation or electron beam sweeping, and then solidifying it.

2. The method for manufacturing a magnetic core according to claim 1, wherein the insulating material in the raw material powder is a powder different from the soft magnetic metal powder.

3. The method for manufacturing a magnetic core according to claim 1, wherein the insulating material is a ceramic powder made of fused silica, borosilicate glass, or silicate glass.

4. The method for producing a magnetic core according to claim 3, wherein the aggregation inhibitor is an aggregation-inhibiting particle having a smaller average primary particle diameter than the soft magnetic metal powder.

5. The method for manufacturing a magnetic core according to claim 4, wherein the aggregation-inhibiting particles are fumed silica particles having an average primary particle diameter of 5 nm or more and 40 nm or less.

6. The method for producing a magnetic core according to claim 3, wherein the amount of the agglomeration inhibitor added to the total amount of the soft magnetic metal powder and the agglomeration inhibitor is 0.1% by volume or more and 1.0% by volume or less.

7. The method for producing a magnetic core according to claim 3, wherein at least a portion of the surface of the soft magnetic metal powder in the raw material powder is covered with the aggregation inhibitor.

8. The soft magnetic metal powder is At least one crystalline metal powder selected from the group consisting of Fe-Si-based metal powder, Fe-Ni-based metal powder, Fe-Si-Al-based metal powder, Fe-Si-Cr-based metal powder, carbonyl iron powder, Fe-Co-based metal powder, and Fe-Co-V-based metal powder, or At least one amorphous metal powder selected from the group consisting of Fe-Si-B-Cr amorphous alloy powder and Fe-B-Si amorphous alloy powder, The method for producing a magnetic core according to claim 3, wherein the mixed metal powder contains two or more types of crystalline metal powder and amorphous metal powder.

9. The method for manufacturing a magnetic core according to claim 3, wherein an insulating layer containing the insulating material is provided on the surface of the soft magnetic metal powder.

10. The method for manufacturing a magnetic core according to claim 3, wherein the amount of insulating material added to the total amount of the soft magnetic metal powder, the aggregation inhibitor, and the insulating material is 1.0% by volume or more and 30.0% by volume or less.

11. The method for manufacturing a magnetic core according to claim 3, wherein the step of fabricating the composite magnetic material involves fabricating a ring-shaped composite magnetic material.

12. A step of manufacturing a magnetic core by the manufacturing method described in any one of claims 1 to 11, A method for manufacturing a coil component, comprising the step of winding a coil conductor around the outer surface of the magnetic core.

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