Abstract: A manufacturing method of a rare-earth magnet includes: manufacturing a sintered body having by performing pressing on a magnetic powder for a rare-earth magnet; and manufacturing a rare-earth magnet by putting the sintered body in a plastic working mold and by performing hot plastic working on the sintered body while pressing the sintered body to give anisotropy to the sintered body. The sintered body has a cuboid shape and includes at least one recessed side face that has a recessed portion curved inward. The plastic working mold includes a lower die, a side die forming a rectangular frame of four side faces, and an upper die slidable in the side die. The hot plastic working is hot upsetting.

Abstract: Provided is a method for manufacturing a rare-earth magnet capable of manufacturing a rare-earth magnet with high degree of orientation by sufficient plastic deformation while suppressing cracks at the side faces of a compact that is plastic-deformed during the hot deformation processing. The method includes a step of preparing a compact S, preparing a plastic processing mold including a die D in which a cavity Ca is provided, and punches P that are slidable in the cavity Ca, the cavity Ca having a cross section that is larger in cross-sectional dimensions than a cross section of the compact S that is orthogonal to a pressing direction by the punches P; and a step of placing the compact S in the cavity Ca and performing hot deformation processing, thus manufacturing an orientational magnet C.

Abstract: A production method includes producing a rare-earth magnet precursor (S?) by performing first hot working in which, in two side surfaces of a sintered body, which are parallel to a pressing direction and are opposite to each other, one side surface is brought to a constrained state to suppress deformation, and the other side surface is brought to an unconstrained state to permit deformation; and producing a rare-earth magnet by performing second hot working in which, in two side surfaces (S?1, S?2) of the rare-earth magnet precursor (S?), which are parallel to the pressing direction, a side surface (S?2), which is in the unconstrained state in the first hot working, is brought to the constrained state to suppress deformation, and a side surface (S?1), which is in the constrained state in the first hot working, is brought to the unconstrained state to permit deformation.

Abstract: A manufacturing method of a rare-earth magnet includes: manufacturing a sintered body having by performing pressing on a magnetic powder for a rare-earth magnet; and manufacturing a rare-earth magnet by putting the sintered body in a plastic working mold and by performing hot plastic working on the sintered body while pressing the sintered body to give anisotropy to the sintered body. The sintered body has a cuboid shape and includes at least one recessed side face that has a recessed portion curved inward. The plastic working mold includes a lower die, a side die forming a rectangular frame of four side faces, and an upper die slidable in the side die. The hot plastic working is hot upsetting.

Abstract: A production method includes producing a rare-earth magnet precursor (S?) by performing first hot working in which, in two side surfaces of a sintered body, which are parallel to a pressing direction and are opposite to each other, one side surface is brought to a constrained state to suppress deformation, and the other side surface is brought to an unconstrained state to permit deformation; and producing a rare-earth magnet by performing second hot working in which, in two side surfaces (S?1, S?2) of the rare-earth magnet precursor (S?), which are parallel to the pressing direction, a side surface (S?2), which is in the unconstrained state in the first hot working, is brought to the constrained state to suppress deformation, and a side surface (S?1), which is in the constrained state in the first hot working, is brought to the unconstrained state to permit deformation.

Abstract: Provided is a method for manufacturing a rare-earth magnet capable of manufacturing a rare-earth magnet with high degree of orientation by sufficient plastic deformation while suppressing cracks at the side faces of a compact that is plastic-deformed during the hot deformation processing. The method includes a step of preparing a compact S, preparing a plastic processing mold including a die D in which a cavity Ca is provided, and punches P that are slidable in the cavity Ca, the cavity Ca having a cross section that is larger in cross-sectional dimensions than a cross section of the compact S that is orthogonal to a pressing direction by the punches P; and a step of placing the compact S in the cavity Ca and performing hot deformation processing, thus manufacturing an orientational magnet C.

Abstract: A forward extrusion forging apparatus includes: a die having a hollow portion whose diameter is reduced at an intermediate position; and a punch that is positioned behind a workpiece placed in the hollow portion, slides in the hollow portion, and extrudes the workpiece ahead of the hollow portion so that the workpiece is forged. An extruding surface of the punch, which extrudes the workpiece, is recessed in a direction opposite an extruding direction in a manner such that a center portion of the extruding surface is most recessed.

Abstract: An iron powder for dust cores is provided which can be formed into a dust core having a high resistivity and having a low iron loss without degrading the mechanical strength. The iron powder for dust cores includes an iron powder and an oxide film on the surface thereof, wherein the oxide film is composed of a Si-based oxide in which the ratio of Si to Fe satisfies Si/Fe?0.8 on an atomic number basis.

Abstract: A method for manufacturing a powder for a magnetic core including at least a process of performing a siliconizing treatment on a surface of an iron powder containing elemental carbon. In the process of siliconizing treatment, a powder containing at least a silicon dioxide is brought into contact with the surface of the iron powder, elemental silicon is detached from the silicon dioxide by heating the powder of silicon dioxide, and the siliconizing treatment is performed by causing the detached elemental silicon to permeate and diffuse into a surface layer of the iron powder. The invention provides a method for manufacturing a powder for a magnetic core, by which loss reduction is achieved.

Abstract: A powder for a dust core comprising a silicon-containing layer formed within a depth of less than 0.15 D from the surface of the surface layer of a soft magnetic metal powder having a particle diameter D and a method for producing the same are provided.

Abstract: A powder for a dust core comprising a silicon-containing layer formed within a depth of less than 0.15 D from the surface of the surface layer of a soft magnetic metal powder having a particle diameter D and a method for producing the same are provided.

Abstract: A method for manufacturing a powder for a magnetic core including at least a process of performing a siliconizing treatment on a surface of an iron powder containing elemental carbon. In the process of siliconizing treatment, a powder containing at least a silicon dioxide is brought into contact with the surface of the iron powder, elemental silicon is detached from the silicon dioxide by heating the powder of silicon dioxide, and the siliconizing treatment is performed by causing the detached elemental silicon to permeate and diffuse into a surface layer of the iron powder. The invention provides a method for manufacturing a powder for a magnetic core, by which loss reduction is achieved.

Abstract: A method for producing a powder for a magnetic core, in which an alkoxide film formation step and a silicone resin film formation step are carried out to form an insulation film composed of an alkoxide film and a silicone resin film on the surface of a pure iron powder, wherein the alkoxide film formation step comprises immersing a pure iron powder in an alkoxide-containing solution which is prepared by mixing a Si alkoxide having at least one organic group having a polar group comprising at least one of N, P, S and O atoms and an Al alkoxide with a dehydrated organic solvent, and drying to remove the dehydrated organic solvent, thereby forming an alkoxide film comprising an Al—Si—O type composite oxide on the surface of the pure iron powder; and the silicone resin film formation step comprises immersing the pure iron powder having the alkoxide film formed thereon in a silicone resin-containing solution which is prepared by mixing a silicone resin with an organic solvent, and drying to remove the organic solv

Abstract: Since a surface of an iron powder is covered with an oxide film composed of a Si-based oxide in which the ratio of Si to Fe satisfies Si/Fe?0.8 on an atomic number basis, an iron powder for dust cores is provided which can be formed into a dust core having a high resistivity and hence having a low iron loss without degrading the mechanical strength.

Abstract: In a stator core composed of a powder compacted magnetic body, a yoke part comprises a protrusion protruding from an axial end face of a tooth. The tooth has an axial length gradually decreases towards an outside along the radial direction of the stator core, and a circumferential length which gradually increases towards an outside along the radial direction of the stator core. In one of the cross sections of stator core perpendicular to a radial direction, the height difference between axial end faces of the yoke part and the tooth is substantially equal to an axial length of a coil end part. Further, a cross-sectional area of the tooth perpendicular to the radial direction is substantially maintained constant along the radial direction, and the cross-sectional area is secured at a junction between the tooth and the yoke part, while half of the cross-sectional area is secured in a circumferential cross section of the yoke part.

Abstract: A core comprises a plurality of core split members having yoke portions and tooth portions and arranged in such a circumferential shape that the yoke portions contact with each other while the tooth portions being directed inward. The core further comprises a ring contacting with the yoke portions, and stoppers mounted on the outer face sides of the yoke portions for fixing the ring on the yoke portions. The yoke portions and the ring are formed in corrugated shape to mesh with each other, and the stoppers are formed with projections that engage with the inner side of the ring. This structure provides both the rotating electrical machine core having the core split members arranged in the circumferential shape and fastened to each other while preventing occurrence of a stress and a positional displacement between the core split members, and a rotating electrical machine.

Abstract: According to the present invention, a dust core having excellent insulating properties, high strength, and high density (high magnetic flux density), a method for producing the same, and an electric motor or reactor having a core member composed of the dust core are provided. Therefore, a method for producing a dust core is provided, such method comprising the following steps: a 1st step of preparing a resin powder 2 and a magnetic powder 1 comprising soft magnetic metal powder (pure iron powder 11) particles each having an insulating film (silica film 12) preliminarily formed on the surface thereof; a 2nd step of obtaining a powder mixture by mixing the magnetic powder 1 and the resin powder 2; and a 3rd step of allowing the resin powder 2 to gel in an atmosphere at a certain temperature, press-molding the powder mixture so as to obtain a press molded body 10, and annealing the press molded body 10 so as to produce a dust core 20.

Abstract: According to the present invention, a magnetic powder for a dust core, which is excellent in terms of insulation properties without causing a decrease in the dust core magnetic flux density, a dust core comprising the magnetic powder, and a motor or a reactor having a core composed of the dust core are provided. Therefore, a magnetic powder 10 for a dust core is characterized in that relatively hard oxide fine powder particles 2 are dispersed over and fixed to the surface of a soft magnetic metal powder particle 1, and that a relatively soft insulating coat 3 is fixed to the oxide fine powder particles 2 and portions where the dispersed and fixed oxide fine powder particles 2 do not exist on the surface of the soft magnetic metal powder particle 1.

Abstract: A stator core is composed of two compacts of compressed powder magnetic cores joined in the axial direction. A yoke portion includes projections projecting axially outward from end surfaces in the axial direction of a tooth. The length in the axial direction of the tooth is gradually reduced radially toward the outside of the stator core, and the length in the circumferential direction of the tooth is gradually increased radially toward the outside of the stator core. A molding is formed by pressing magnetic powder placed in a die by a single punch placed on one side in the axial direction and two punches placed parallel to each other on the other side in the axial direction. The stator core for a rotary electric machine is thus produced.

Abstract: A process for producing a magnetic powder which is sufficiently reduced in core losses such as iron loss and hysteresis loss and has sufficient strength; and a process for producing a dust core. The process for magnetic powder production comprises using a magnetic-material powder produced by water atomization as a raw powder and subjecting the powder to spheroidizing in which a mechanical impact is applied to the powder to spheroidize the powder particles. After the spheroidizing, the powder is subjected to a grain enlarging treatment in which the powder is annealed at a temperature not lower than the austenite transformation point. The process for dust core production comprises compacting the magnetic powder thus produced.