# US 10,121,589 B2 · Method and apparatus for preparing rare earth sintered magnet > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,121,589 B2 - Document ID: US10121589B2 - Status: Granted - Kind: B2 - Application number: 14/578,771 - Filed: 2014-12-22 - Published: 2015-06-25 - Granted: 2018-11-06 - Earliest claimed: 2013-12-24 - Assignees: Shin-Etsu Chemical Co., Ltd. - Applicants: Shin-Etsu Chemical Co., Ltd. - Inventors: Mitsuo Kitagawa; Kazuaki Sakaki - Web page: https://patentgrep.com/patent/US10121589B2 ## CPC - H01F 41/0273: {Imparting anisotropy (methods and devices for magnetising permanent magnets H01F13/003)} - B22F 3/02: Compacting only - B22F 3/03: Press-moulding apparatus therefor - B30B 15/302: {Feeding material in particulate or plastic state to moulding presses} - B22F 3/12: Both compacting and sintering (by forging B22F3/17) - B22F 2999/00: Aspects linked to processes or compositions used in powder metallurgy - C22C 2202/02: Magnetic - H01F 1/0577: {sintered} - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - B30B: PRESSES IN GENERAL (producing ultra-high pressure or ultra-high pressure and high temperature to effect modifications of a substance, e.g. for making artificial diamonds B01J3/00 ){(compressing means for refuse receptacles B65F1/1405)} - C22C: ALLOYS (treatment of alloys C21D, C22F) ## Abstract A mold comprising a die, an upper punch, and a lower punch, the pressure surface of one or both of the upper and lower punches being shaped non-planar, a cavity being defined between the die and the lower punch, is combined with a feeder including a shooter provided with a main sieve at its lower end port, the main sieve having a sifting surface of substantially the same non-planar shape as the pressure surface. A rare earth sintered magnet is prepared by feeding an alloy powder into the cavity through the shooter and sieve while applying weak vibration and vertical reciprocation to the shooter, applying a uniaxial pressure to the alloy powder fill in the cavity under a magnetic field to form a precursor, and heat treating the precursor. ## Claims ### Claim 1 A method for preparing a rare earth sintered magnet from a corresponding alloy powder using a mold and a feeder, said mold comprising a die, an upper punch having a pressure surface, and a lower punch having a pressure surface, the pressure surface of one or both of the upper and lower punches being shaped non-planar, a cavity being defined between the die and the lower punch, the feeder including a shooter having a lower end port for passage of the alloy powder, the port being aligned with the cavity, said method comprising the steps of feeding the alloy powder from the feeder into the cavity through the shooter until the cavity is filled with the alloy powder, compressing the alloy powder fill in the cavity under a magnetic field between the upper and lower punches for uniaxial pressure molding to form a precursor, and heat treating the precursor, wherein the shooter is provided with a main sieve at its lower end port such that the main sieve is disposed closely above the cavity, the main sieve having a sifting surface of non-planar shape as the pressure surface of the upper or lower punch, during the step of feeding the alloy powder into the cavity through the shooter, vibration and vertical reciprocation are applied to the shooter to assist the alloy powder to pass through the main sieve and fall into the cavity. ### Claim 2 (depends on 1) The method of claim 1 wherein the main sieve has an opening of 10 to 22 mesh. ### Claim 3 (depends on 1) The method of claim 1 wherein at least a portion of the pressure surface of one or both of the upper and lower punches is a curved surface of arch or inverse arch shape. ### Claim 4 (depends on 1) The method of claim 1 wherein the pressure surface of the upper punch is a curved surface of arcuate arch shape, and the pressure surface of the lower punch consists of a curved surface segment of arcuate arch shape and two flanks extending from the opposite edges of the curved surface segment and inclined toward the convex side of the arch. ### Claim 5 (depends on 1) The method of claim 1 wherein the shooter is provided with at least one auxiliary sieve in its interior above the main sieve. ### Claim 6 (depends on 5) The method of claim 5 wherein the auxiliary sieve has a sifting surface of non-planar shape as the sifting surface of the main sieve. ### Claim 7 (depends on 5) The method of claim 5 wherein the main and auxiliary sieves are arranged such that their opening becomes coarser toward the top. ### Claim 8 (depends on 1) The method of claim 1 wherein the feeder includes a powder distributor disposed above the main sieve for distributing the alloy powder over the main sieve so that the alloy powder may fall throughout the main sieve. ### Claim 9 (depends on 1) The method of claim 1 wherein the feeder includes a piston vibrator for producing vibration. ### Claim 10 (depends on 9) The method of claim 9 wherein the piston vibrator produces vibration at a frequency of 30 to 200 Hz and a vibromotive force of 30 to 300 N. ### Claim 11 (depends on 1) The method of claim 1 wherein the feeder includes a pneumatic hammer for producing vertical reciprocation. ### Claim 12 (depends on 11) The method of claim 11 wherein the pneumatic hammer produces vertical reciprocation at a frequency of 1 to 10 Hz and an amplitude of 2 to 10 mm. ### Claim 13 An apparatus for preparing a rare earth sintered magnet precursor from a corresponding alloy powder, comprising a mold and a feeder, said mold comprising a die, an upper punch having a pressure surface, and a lower punch having a pressure surface, the pressure surface of one or both of the upper and lower punches being shaped non-planar, a cavity being defined between the die and the lower punch, said feeder comprising a shooter having a lower end port for passage of the alloy powder, the port being in alignment with the mold cavity, a main sieve provided at the lower end port of the shooter, the main sieve having a sieve surface of non-planar shape as the pressure surface of the upper or lower punch, and means for applying vibration and vertical reciprocation to the shooter, wherein the alloy powder is fed into the mold cavity through the shooter while vibration and vertical reciprocation are applied to the shooter to assist the alloy powder to pass through the main sieve and fall into the cavity, and the upper and lower punches are forced relative to each other to apply a uniaxial pressure to the alloy powder in the cavity under a magnetic field to form a precursor.