Abstract: A method for manufacturing a dust core, including: a step of preparing a raw material powder including a coated pure iron powder composed of a plurality of pure iron particles each having an insulating coating layer, a coated iron alloy powder composed of a plurality of iron alloy particles each having an insulating coating layer, and a metal soap; a step of manufacturing a molded article by performing a compression molding of the raw material powder filled in a mold; and a step of performing a heat treatment of the molded article to eliminate distortions in the coated pure iron powder and the coated iron alloy powder, wherein a difference Tm?Td between a melting point Tm of the metal soap and a temperature Td of the mold in the step of manufacturing the molded article is greater than or equal to 90° C.

Abstract: A core for use in an axial gap rotating electric machine, the core including: a yoke having an annular plate shape; and a plurality of teeth having a columnar shape arranged at intervals in a circumferential direction of the yoke, wherein the yoke has: an outer-circumferential face; an inner-circumferential face; a first face having a flat shape connecting the outer-circumferential face and the inner-circumferential face to each other; and a plurality of recessed portions connected to the first face, each of the plurality of teeth has an outer-circumferential face protruding in an axial direction of the yoke with respect to the first face, each of the plurality of recessed portions are connected to at least a portion of each one of the plurality of teeth in a circumferential direction of the outer-circumferential face, all shortest distances between at least one of an outer-circumferential edge of the first face and an inner-circumferential edge of the first face and the outer-circumferential faces of the plu

Abstract: A core is a core included in a rotor or a stator of an axial-gap rotating electrical machine, in which the core includes a block-shaped first member and a plate-shaped second member that are constituted by powder compacts; the first member includes a first surface that faces the second member, and a first coupling portion that is formed at the first surface; the second member includes a second surface that faces the first surface, and a second coupling portion that is formed at the second surface and that is coupled to the first coupling portion; one of the first coupling portion and the second coupling portion is constituted by a protrusion, and the other one is constituted by a recess having a shape corresponding to the protrusion.

Abstract: A method for manufacturing a powder magnetic core, including a step of compacting a raw material powder to form a compact, a step of performing a first heat treatment on the compact to obtain a first heat-treated body, and a step of performing a second heat treatment on the first heat-treated body to obtain a second heat-treated body, wherein the raw material powder contains a soft magnetic powder and a lubricant that has a melting point Tm, the first heat treatment is performed in a temperature range from Tm to Tm+50° C. inclusive for a time longer than 10 minutes, and the second heat treatment is performed in a temperature range from 400° C. to 900° C. inclusive for a time of 3 minutes to 90 minutes inclusive, the temperature range of the second heat treatment being higher than the temperature range of the first heat treatment.

Abstract: A core for use in an axial gap rotating electric machine, the core including: a yoke having an annular plate shape; and a plurality of teeth having a columnar shape arranged at intervals in a circumferential direction of the yoke, wherein the yoke has: an outer-circumferential face; an inner-circumferential face; a first face having a flat shape connecting the outer-circumferential face and the inner-circumferential face to each other; and a plurality of recessed portions connected to the first face, each of the plurality of teeth has an outer-circumferential face protruding in an axial direction of the yoke with respect to the first face, each of the plurality of recessed portions are connected to at least a portion of each one of the plurality of teeth in a circumferential direction of the outer-circumferential face, all shortest distances between at least one of an outer-circumferential edge of the first face and an inner-circumferential edge of the first face and the outer-circumferential faces of the plu

Abstract: A core used in an axial-gap rotating electric device includes an annular back yoke and a plurality of teeth protruding in an axial direction that is perpendicular to a first flat surface of the back yoke. The plurality of teeth are provided on the first flat surface at intervals in a circumferential direction. The back yoke and the teeth are constituted of an integrally-molded powder compact. A first curved section that connects a peripheral surface of each tooth and the first flat surface of the back yoke is provided at a corner between the tooth and the back yoke. The first curved section has a curvature radius ranging between 0.2 mm and 1.5 mm inclusive.

Abstract: A powder compaction mold includes a die and upper and lower punches configured to fit into the die and is configured to compress a powder between the upper and lower punches to manufacture a powder compact. Of the members forming the powder compaction mold, at least one of two members in sliding contact with each other has therein a vent passage through which gas is vented from a filling space for the powder surrounded by the die and the lower punch to an outside of the powder compaction mold. The vent passage has a gas intake port that is open to a clearance section formed between the two members and connecting to the filling space.

Abstract: A compact is provided. When the compact is used for a magnetic core, a magnetic path cross section has a cross-sectional perimeter of more than 20 mm, and at least part of a surface of the compact is covered with an iron-based oxide film having an average thickness of 0.5 ?m or more and 10.0 ?m or less. Letting the proportion of the surface area of the compact to the volume of the compact be surface area/volume, the content of Fe3O4 present in the iron-based oxide film with respect to 100% by volume of the compact satisfies any one of (1) to (3): (1) less than 0.085% by volume when the (surface area/volume) is 0.40 mm?1 or less, (2) 0.12% or less by volume when the (surface area/volume) is more than 0.40 mm?1 and 0.60 mm?1 or less, and (3) 0.15% or less by volume when the (surface area/volume) is more than 0.60 mm?1.

Abstract: A method for manufacturing a powder magnetic core, including a step of compacting a raw material powder to form a compact, a step of performing a first heat treatment on the compact to obtain a first heat-treated body, and a step of performing a second heat treatment on the first heat-treated body to obtain a second heat-treated body, wherein the raw material powder contains a soft magnetic powder and a lubricant that has a melting point Tm, the first heat treatment is performed in a temperature range from Tm to Tm+50° C. inclusive for a time longer than 10 minutes, and the second heat treatment is performed in a temperature range from 400° C. to 900° C. inclusive for a time of 3 minutes to 90 minutes inclusive, the temperature range of the second heat treatment being higher than the temperature range of the first heat treatment.

Abstract: A core is a core included in a rotor or a stator of an axial-gap rotating electrical machine, in which the core includes a block-shaped first member and a plate-shaped second member that are constituted by powder compacts; the first member includes a first surface that faces the second member, and a first coupling portion that is formed at the first surface; the second member includes a second surface that faces the first surface, and a second coupling portion that is formed at the second surface and that is coupled to the first coupling portion; one of the first coupling portion and the second coupling portion is constituted by a protrusion, and the other one is constituted by a recess having a shape corresponding to the protrusion.

Abstract: A dust core includes: a plurality of soft magnetic particles composed of an iron-based material; an insulating layer including a coating layer that is composed mainly of a phosphate and covers the surface of the soft magnetic particles; and insulating pieces containing a constituent material of the insulating layer, each of the insulating pieces being surrounded by at least three mutually adjacent ones of the soft magnetic particles while separated from the insulating layer.

Abstract: A method for manufacturing a dust core, including: a step of preparing a raw material powder including a coated pure iron powder composed of a plurality of pure iron particles each having an insulating coating layer, a coated iron alloy powder composed of a plurality of iron alloy particles each having an insulating coating layer, and a metal soap; a step of manufacturing a molded article by performing a compression molding of the raw material powder filled in a mold; and a step of performing a heat treatment of the molded article to eliminate distortions in the coated pure iron powder and the coated iron alloy powder, wherein a difference Tm?Td between a melting point Tm of the metal soap and a temperature Td of the mold in the step of manufacturing the molded article is greater than or equal to 90° C.

Abstract: A compact is provided. When the compact is used for a magnetic core, a magnetic path cross section has a cross-sectional perimeter of more than 20 mm, and at least part of a surface of the compact is covered with an iron-based oxide film having an average thickness of 0.5 ?m or more and 10.0 ?m or less. Letting the proportion of the surface area of the compact to the volume of the compact be surface area/volume, the content of Fe3O4 present in the iron-based oxide film with respect to 100% by volume of the compact satisfies any one of (1) to (3): (1) less than 0.085% by volume when the (surface area/volume) is 0.40 mm?1 or less, (2) 0.12% or less by volume when the (surface area/volume) is more than 0.40 mm?1 and 0.60 mm?1 or less, and (3) 0.15% or less by volume when the (surface area/volume) is more than 0.60 mm?1.

Abstract: A powder compaction mold includes a die and upper and lower punches configured to fit into the die and is configured to compress a powder between the upper and lower punches to manufacture a powder compact. Of the members forming the powder compaction mold, at least one of two members in sliding contact with each other has therein a vent passage through which gas is vented from a filling space for the powder surrounded by the die and the lower punch to an outside of the powder compaction mold. The vent passage has a gas intake port that is open to a clearance section formed between the two members and connecting to the filling space.

Abstract: A dust core includes: a plurality of soft magnetic particles composed of an iron-based material; an insulating layer including a coating layer that is composed mainly of a phosphate and covers the surface of the soft magnetic particles; and insulating pieces containing a constituent material of the insulating layer, each of the insulating pieces being surrounded by at least three mutually adjacent ones of the soft magnetic particles while separated from the insulating layer.