Powder compacting apapratus and method of producing a rare-earth magnet using the same

A method of producing a rare-earth magnet by performing a compaction process comprising the steps of:

• supplying a powder compacting apparatus comprising an airtight container capable of storing a rare-earth alloy powder therein, an airtight feeder box movable between a powder-filling position and a retracted position, and an airtight powder supply device adapted to supply the rare-earth alloy powder from said container into said feeder box without exposing the rare-earth alloy powder to an atmospheric air;
• storing a rare-earth alloy powder in said container;
• operating said powder supply device to supply the rare-earth alloy powder from said container into said feeder box without exposing the rare-earth alloy powder to atmospheric air;
• and
• compacting the rare-earth alloy powder supplied from said feeder box, thus producing a compact.

A method of producing a rare-earth magnet, comprising the steps of:

• producing a rare-earth alloy powder through pulverization by a pulverization apparatus in which an oxygen concentration in a pulverization atmosphere is controlled to be 5000 volume ppm or less;
• supplying the rare-earth alloy powder into an airtight container without exposing the rare-earth alloy powder to atmospheric air;
• transferring the rare-earth alloy powder from the container into an airtight feeder box without exposing the rare-earth alloy powder to atmospheric air;
• filling from the feeder box the rare-earth alloy powder into a cavity formed in a die of a compacting apparatus;
• and
• forming a compact by pressing the rare-earth alloy powder.

A powder-filling device, comprising:

• a feeder box having an enclosure forming an airtight space for containing a powder therein;
• a level sensor for measuring an upper surface level of the powder contained in said space;
• and
• powder supply means for supplying the powder into said space based on an output from the level sensor.