R-T-B-M-C Sintered Magnet And Production Method And An Apparatus For Manufacturing The R-T-B-M-C Sintered Magnet

The method for preparing an R-T-B-M-C sintered rare earth magnet from an R-T-B-M-C alloy powder in a mold comprising the steps of;

• mixing the R-T-B-M-C alloy powder having a predetermined particle size with a lubricant under an inert gas environment to produce an R-T-B-M-C alloy powder including the lubricant,
• filling the mold with the R-T-B-M-C alloy powder including the lubricant to a filling density under the inert gas environment,
• compressing the R-T-B-M-C alloy powder including the lubricant in the mold under a predetermined pressure between 0.2 MPa and 2 MPa,
• orienting the R-T-B-M-C alloy powder including the lubricant by applying a magnetic field to the R-T-B-M-C alloy powder including the lubricant under the inert gas environment to form a compact,
• sintering the compact,
• subjecting the sintered compact to a heat treatment.

An apparatus for preparing an R-T-B-M-C sintered rare earth magnet from an R-T-B-M-C alloy powder including a lubricant in a warehouse and under an inert gas environment comprising;

• a support disposed in the warehouse,
• an alloy powder feeding mechanism disposed on said support,
• said alloy powder feeding mechanism including a container for storing the R-T-B-M-C alloy powder including the lubricant and a feeder for distributing the R-T-B-M-C alloy powder including the lubricant and a powder mover extending between a first end disposed in communication with said container and a second end disposed in communication with said feeder for moving the R-T-B-M-C alloy powder including the lubricant from said container to said feeder,
• said container including a wall of pentagonal shape in cross section extending between and an opening and an exit defining a main chamber extending between said wall and said opening and said exit for storing the R-T-B-M-C alloy powder including the lubricant,
• said container further including a neck extending outwardly from said exit of said container and disposed in communication with said powder mover in a perpendicular relationship at said first end of said powder mover for transferring the R-T-B-M-C alloy powder including the lubricant from said main chamber of said container to said powder mover,
• said feeder including a receiving portion having a trapezoidal shape in cross section disposed in communication with said second end of said powder mover in a perpendicular relationship for accepting the R-T-B-M-C alloy powder including the lubricant from said container,
• said feeder including a chute of tubular shape extending outwardly from sad receiving portion at an obtuse angle relative to said receiving portion to a discharging end for distributing the R-T-B-M-C alloy powder including the lubricant from the feeder,
• a filling mechanism disposed adjacent to and spaced apart from said discharging end of said feeder for accepting the R-T-B-M-C alloy powder including the lubricant from said discharging end of said feeder,
• said filling mechanism further including a mold of U shape in cross section having a base and a plurality of sides extending outwardly from said base in a perpendicular relationship to define a cavity extending between said base and said sides for containing the R-T-B-M-C alloy powder including the lubricant,
• said filling mechanism further including a vibration device disposed below said base of said mold for supporting said mold and oscillating said mold containing the R-T-B-M-C alloy powder including the lubricant to allow the R-T-B-M-C alloy powder including the lubricant to reach a filling density of between 2.8 g/cm3 and 3.2 g/cm3,
• a cover of T-shape in cross section disposed on said mold and engaging said sides of said mold for closing said mold,
• said cover defining an inner surface for engaging said sides of said mold and an outer surface and a projection extending outwardly and perpendicularly from said inner surface and abutting said sides of said mold toward said base of said mold to engage the R-T-B-M-C alloy powder including the lubricant in said mold,
• a press mechanism dispose adjacent to and spaced apart from said filling mechanism for compressing the R-T-B-M-C alloy powder including the lubricant in said mold and subjecting the R-T-B-M-C alloy powder including the lubricant in the mold to a magnetic field,
• said press mechanism further including a pair of punches having an upper punch and a lower punch disposed axially aligned and spaced apart with one another along a center axis for compressing the R-T-B-M-C alloy powder including the lubricant,
• said press mechanism further including an orienting device of tubular shape disposed on said center axis between said upper punch and said lower punch for magnetizing the R-T-B-M-C alloy powder including the lubricant,
• said orienting device including a plurality of coils extending annularly about said center axis defining an orienting chamber extending along said center axis for allowing a DC current to run through said coils to provide a magnetic field having a magnetic field of at least 3.5 T,
• said upper punch defining an upper punch surface for engaging said outer surface of said cover,
• said lower press defining a lower punch surface for engaging and supporting said base of said mold,
• each of said punches including an air cylinder attached thereto for actuating said upper punch and said lower punch between a first position of said upper punch surface being spaced apart from said outer surface of said cover of said mold and a second position of said upper punch engaging said outer surface of said cover of said mold sandwiching said mold between said upper punch and said lower punch for compressing the R-T-B-M-C alloy powder including the lubricant in the mold and in said orienting chamber for magnetizing the R-T-B-M-C alloy powder including the lubricant,
• a stacking device disposed adjacent to said pressing mechanism for storing said mold after compressing and magnetizing the R-T-B-M-C alloy powder including the lubricant in said pressing mechanism.