METHOD FOR MANUFACTURING RING MAGNET, AND ROTOR HAVING RING MAGNET

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PROBLEM TO BE SOLVED : To overcome a problem of a ring magnet attached to a rotor causing the larger vibration of the rotor because of the magnet having a density changing in a circumferential direction. SOLUTION : The method for manufacturing a ring magnet comprises the steps of : roughly pulverizing a rare earth alloy into rare earth magnetic coarse powder, followed by re-pulverizing the coarse powder into rare earth magnetic powder; using a sieve of mesh to selectively sort the resultant rare earth magnetic powder; adding resin to the sorted rare earth magnetic material powder to prepare mixed powder; preparing a compressed object by charging the mixed powder into a mold having an outer periphery mold for restricting an outer peripheral surface of the compressed object, and an inner periphery mold for restricting an inner peripheral surface of the compressed object, and performing the compression molding; preparing hardened object by hardening the compressed object in a high-temperature atmosphere; and rustproofing a surface of the hardened object. COPYRIGHT : (C)2012, JPO&INPIT