(19)
(11) EP 2 767 992 A8

(12) CORRECTED EUROPEAN PATENT APPLICATION
published in accordance with Art. 153(4) EPC

(15) Correction information:
Corrected version no 1 (W1 A1)

(48) Corrigendum issued on:
26.11.2014 Bulletin 2014/48

(88) Date of publication A3:
20.08.2014 Bulletin 2014/34

(43) Date of publication:
20.08.2014 Bulletin 2014/34

(21) Application number: 12840664.2

(22) Date of filing: 09.10.2012
(51) International Patent Classification (IPC): 
H01F 41/02(2006.01)
C22C 33/02(2006.01)
H01F 1/057(2006.01)
 B22F 1/00(2006.01)
C22C 38/00(2006.01)
H01F 1/08(2006.01)
(86) International application number:
PCT/JP2012/076065
(87) International publication number:
WO 2013/054778 (18.04.2013 Gazette 2013/16)
(84) Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30) Priority: 11.10.2011 JP 2011224115

(71) Applicant: TOYOTA JIDOSHA KABUSHIKI KAISHA
Toyota-shi, Aichi-ken, 471-8571 (JP)

(72) Inventors:
  • SAKUMA, Noritsugu
    Toyota-shi, Aichi-ken, 471-8571 (JP)
  • KISHIMOTO, Hidefumi
    Toyota-shi, Aichi-ken, 471-8571 (JP)
  • MIYAMOTO, Noritaka
    Toyota-shi, Aichi-ken, 471-8571 (JP)
  • KATO, Akira
    Toyota-shi, Aichi-ken, 471-8571 (JP)
  • MANABE, Akira
    Toyota-shi, Aichi-ken, 471-8571 (JP)
  • ICHIGOZAKI, Daisuke
    Toyota-shi, Aichi-ken, 471-8571 (JP)
  • SHOJI, Tetsuya
    Toyota-shi, Aichi-ken, 471-8571 (JP)
  • HARAKAWA, Shoichi
    Toyota-shi, Aichi-ken, 471-8571 (JP)

(74) Representative: Kuhnen & Wacker 
Patent- und Rechtsanwaltsbüro Prinz-Ludwig-Straße 40A
85354 Freising
85354 Freising (DE)

   


(54) MANUFACTURING METHOD FOR MAGNETIC POWDER FOR FORMING SINTERED BODY OF RARE-EARTH MAGNET PRECURSOR


(57) A method for producing magnetic powder for forming a sintered body that is a precursor of a rare-earth magnet. Provided is a method for producing magnetic powder for forming a sintered body that is a precursor of a rare-earth magnet, which can produce magnetic powder with a structure containing optimal nanosized crystal grains by accurately and efficiently sorting out magnetic powder containing no coarse grains in the structure thereof. A method for producing magnetic powder p for forming a sintered body S that is a precursor of a rare-earth magnet, the sintered body S including an Nd-Fe-B-based main phase with a nanocrystalline structure, and a grain boundary phase around the main phase, and the rare-earth magnet being adapted to be formed by applying hot deformation processing to the sintered body S for imparting anisotropy thereto and diffusing an alloy for improving coercivity therein, the method including discharging a metal melt onto a chill roll R to produce a quenched ribbon B, and grinding the quenched ribbon B into grains in the size range of 50 to 1000 µm to produce magnetic powder in the mass range of 0.0003 to 0.3 mg; conducting a test to see whether or not the magnetic powder in the mass range adsorbs onto a magnet with a surface magnetic flux density of 2 mT or less, and sorting out magnetic powder p that has not adsorbed onto the magnet, as the magnetic powder for forming the sintered body S.