Method for producing sintered rare-earth magnet and powder-filling container for producing such magnet

Abstract

Provided is an easy and inexpensive method for producing a sintered rare-earth magnet having cavities, such as slits, for making the magnet less likely to be influenced from eddy currents and/or performing a grain boundary diffusion process. The method for producing a sintered rare-earth magnet includes performing the following successive processes: a filling process ((a), (b)) for filling a powder of rare-earth magnet alloy into a powder-filling container together with a cavity-forming member; an aligning process (b) for aligning the rare-earth magnet alloy powder in a magnetic field; and a sintering process (e) for sintering the rare-earth magnet alloy powder by heating the rare-earth magnet alloy powder in a state of being held in the powder-filling container, wherein (d) the cavity-forming member is removed after the aligning process is completed and before the rare-earth magnet alloy powder begins to be sintered.

1 . A method for producing a sintered rare-earth magnet, wherein a sintered rare-earth magnet having a cavity is produced by performing following successive processes:
 a) a filling process for filling a powder of rare-earth magnet alloy into a powder-filling container together with a cavity-forming member;   b) an aligning process for aligning the rare-earth magnet alloy powder in a magnetic field; and   c) a sintering process for sintering the rare-earth magnet alloy powder by heating the rare-earth magnet alloy powder in a state of being held in the powder-filling container,   wherein   d) the cavity-forming member is removed after the aligning process is completed and before the rare-earth magnet alloy powder begins to be sintered.   
     
     
         2 . The method for producing a sintered rare-earth magnet according to  claim 1 , wherein the removal of the cavity-forming member is performed before the sintering process is initiated. 
     
     
         3 . The method for producing a sintered rare-earth magnet according to  claim 1 , wherein the cavity-forming member is a plate-shaped member or a rod-shaped member. 
     
     
         4 . The method for producing a sintered rare-earth magnet according to  claim 3 , wherein the rare-earth magnet alloy powder is aligned in a magnetic field parallel to the cavity-forming member in the aligning process. 
     
     
         5 . The method for producing a sintered rare-earth magnet according to  claim 1 , wherein a binder is filled into the powder-filling container together with the rare-earth magnet alloy powder in the filling process. 
     
     
         6 . The method for producing a sintered rare-earth magnet according to  claim 1 , wherein an embedding member is filled into the cavity after the removal of the cavity-forming member. 
     
     
         7 . The method for producing a sintered rare-earth magnet according to  claim 1 , wherein:
 the rare-earth magnet alloy is an Nd—Fe—B magnet alloy; and   a diffusing process for diffusing Dy and/or Tb into the sintered compact is performed by injecting a substance containing Dy and/or Tb into the cavity of the sintered compact obtained by the sintering process.   
     
     
         8 . The method for producing a sintered rare-earth magnet according to  claim 7 , wherein an embedding member is filled into the cavity after the diffusing process. 
     
     
         9 . The method for producing a sintered rare-earth magnet according to  claim 6 , wherein the embedding member is made of an insulating material. 
     
     
         10 . The method for producing a sintered rare-earth magnet according to  claim 1 , wherein the filling process includes inserting the cavity-forming member into the powder-filling container through an insertion opening formed in either the powder-filling container or a lid of the powder-filling container, and the removal process includes pulling out the cavity-forming member from the insertion opening. 
     
     
         11 . A powder-filling container for producing a sintered rare-earth magnet, comprising:
 a mold into which a powder of rare-earth magnet alloy is to filled;   a lid to be attached to the mold; and   an insertion opening, formed in either the mold or the lid, for allowing insertion of a cavity-forming member.   
     
     
         12 . A powder-filling container for producing a sintered rare-earth magnet, comprising:
 a mold into which a powder of rare-earth magnet alloy is to be filled;   a lid to be attached to the mold; and   a cavity-forming member provided on either the mold or the lid.   
     
     
         13 . The method for producing a sintered rare-earth magnet according to  claim 8 , wherein the embedding member is made of an insulating material.