# US 2013/0278367 A1 · Arcuate magnet having polar-anisotropic orientation, and method and molding die for producing it > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278367 A1 - Document ID: US20130278367A1 - Status: Published application - Kind: A1 - Application number: 13/976,254 - Filed: 2011-12-21 - Published: 2013-10-24 - Earliest claimed: 2010-12-28 - Assignees: Hitachi Metals, Ltd. - Inventors: Takeshi Yoshida; Mikio Shindoh - Web page: https://patentgrep.com/patent/US20130278367A1 ## CPC - H01F 7/02: Permanent magnets {[PM]} - B30B 11/027: {Particular press methods or systems} - H01F 41/0273: {Imparting anisotropy (methods and devices for magnetising permanent magnets H01F13/003)} - B22F 3/02: Compacting only - B22F 3/03: Press-moulding apparatus therefor - B22F 2998/10: Processes characterised by the sequence of their steps - B22F 2999/00: Aspects linked to processes or compositions used in powder metallurgy - C22C 2202/02: Magnetic - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - B30B: PRESSES IN GENERAL (producing ultra-high pressure or ultra-high pressure and high temperature to effect modifications of a substance, e.g. for making artificial diamonds B01J3/00 ){(compressing means for refuse receptacles B65F1/1405)} - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - C22C: ALLOYS (treatment of alloys C21D, C22F) ## Abstract A die apparatus for molding an arcuate magnet having polar-anisotropic orientation in a magnetic field, which comprises a die made of non-magnetic cemented carbide, which is arranged in a parallel magnetic field generated by a pair of opposing magnetic field coils; an arcuate-cross-sectional cavity having an inner arcuate wall, an outer arcuate wall and two side walls, which is disposed in the die; a central ferromagnetic body arranged on the side of the outer arcuate wall of the cavity; and a pair of side ferromagnetic bodies symmetrically arranged on both side wall sides of the cavity; the cavity being arranged such that its radial direction at a circumferential center thereof is identical with the direction of the parallel magnetic field; the width of the central ferromagnetic body being smaller than the width of the cavity in a direction perpendicular to the parallel magnetic field; and a pair of the side ferromagnetic bodies being arranged such that the cavity is positioned in a region sandwiched by a pair of the side ferromagnetic bodies. ## Claims ### Claim 1 A die apparatus for molding an arcuate magnet having polar-anisotropic orientation in a magnetic field, which comprises a die made of non-magnetic cemented carbide, which is arranged in a parallel magnetic field generated by a pair of opposing magnetic field coils; an arcuate-cross-sectional cavity having an inner arcuate wall, an outer arcuate wall and two side walls, which is disposed in said die; a central ferromagnetic body arranged on the side of the outer arcuate wall of said cavity with distance from said cavity; and a pair of side ferromagnetic bodies symmetrically arranged on both side wall sides of said cavity with distance from said cavity; said cavity being arranged such that its radial direction at a circumferential center thereof is identical with the direction of said parallel magnetic field; the width of said central ferromagnetic body being smaller than the width of said cavity in a direction perpendicular to said parallel magnetic field, when viewed from above; and a pair of said side ferromagnetic bodies being arranged such that said cavity is positioned in a region sandwiched by a pair of said side ferromagnetic bodies. ### Claim 2 (depends on 1) The die apparatus according to claim 1, wherein said central ferromagnetic body is arranged on a radial-direction line passing through a circumferential middle point of said cavity, and has a symmetrical shape with respect to said line, when viewed from above. ### Claim 3 (depends on 1) The die apparatus according to claim 1, wherein said central ferromagnetic body has a symmetrical shape with respect to a plane, which passes through a middle point of said central ferromagnetic body in the direction of said magnetic field and is perpendicular to the direction of said magnetic field; and wherein another cavity and another pair of side ferromagnetic bodies are arranged symmetrically with respect to said plane. ### Claim 4 (depends on 1) The die apparatus according to claim 1, wherein said central ferromagnetic body and/or said side ferromagnetic bodies are rectangular when viewed from above. ### Claim 5 (depends on 1) The die apparatus according to claim 1, wherein an angle between each side wall of said cavity and a surface of each of said side ferromagnetic bodies opposing said side wall is more than 0°. ### Claim 6 A method for producing an arcuate magnet having polar-anisotropic orientation, using a die apparatus comprising a die made of non-magnetic cemented carbide, which is arranged in a parallel magnetic field generated by a pair of opposing magnetic field coils; an arcuate-cross-sectional cavity having an inner arcuate wall, an outer arcuate wall and two side walls, which is disposed in said die; a central ferromagnetic body arranged on the side of the outer arcuate wall of said cavity with distance from said cavity; and a pair of side ferromagnetic bodies symmetrically arranged on both side wall sides of said cavity with distance from said cavity; said cavity being arranged such that its radial direction at a circumferential center thereof is identical with the direction of said parallel magnetic field; the width of said central ferromagnetic body being smaller than the width of said cavity in a direction perpendicular to said parallel magnetic field, when viewed from above; and a pair of said side ferromagnetic bodies being arranged such that said cavity is positioned in a region sandwiched by a pair of said side ferromagnetic bodies; magnetic powder charged into said cavity being compression-molded in said parallel magnetic field. ### Claim 7 (depends on 6) The method according to claim 6, wherein said magnetic powder is substantially made of R-TM-B, wherein R is at least one of rare earth elements including Y, and TM is at least one of transition metals. ### Claim 8 (depends on 6) An arcuate magnet having polar-anisotropic orientation, which is produced by the method recited in claim 6. ### Claim 9 (depends on 2) The die apparatus according to claim 2, wherein said central ferromagnetic body has a symmetrical shape with respect to a plane, which passes through a middle point of said central ferromagnetic body in the direction of said magnetic field and is perpendicular to the direction of said magnetic field; and wherein another cavity and another pair of side ferromagnetic bodies are arranged symmetrically with respect to said plane. ### Claim 10 (depends on 2) The die apparatus according to claim 2, wherein said central ferromagnetic body and/or said side ferromagnetic bodies are rectangular when viewed from above. ### Claim 11 (depends on 3) The die apparatus according to claim 3, wherein said central ferromagnetic body and/or said side ferromagnetic bodies are rectangular when viewed from above. ### Claim 12 (depends on 9) The die apparatus according to claim 9, wherein said central ferromagnetic body and/or said side ferromagnetic bodies are rectangular when viewed from above. ### Claim 13 (depends on 2) The die apparatus according to claim 2, wherein an angle between each side wall of said cavity and a surface of each of said side ferromagnetic bodies opposing said side wall is more than 0°. ### Claim 14 (depends on 3) The die apparatus according to claim 3, wherein an angle between each side wall of said cavity and a surface of each of said side ferromagnetic bodies opposing said side wall is more than 0°. ### Claim 15 (depends on 4) The die apparatus according to claim 4, wherein an angle between each side wall of said cavity and a surface of each of said side ferromagnetic bodies opposing said side wall is more than 0°. ### Claim 16 (depends on 9) The die apparatus according to claim 9, wherein an angle between each side wall of said cavity and a surface of each of said side ferromagnetic bodies opposing said side wall is more than 0°. ### Claim 17 (depends on 10) The die apparatus according to claim 10, wherein an angle between each side wall of said cavity and a surface of each of said side ferromagnetic bodies opposing said side wall is more than 0°. ### Claim 18 (depends on 11) The die apparatus according to claim 11, wherein an angle between each side wall of said cavity and a surface of each of said side ferromagnetic bodies opposing said side wall is more than 0°. ### Claim 19 (depends on 12) The die apparatus according to claim 12, wherein an angle between each side wall of said cavity and a surface of each of said side ferromagnetic bodies opposing said side wall is more than 0°.