Patents by Inventor Koki Tokuhara
Koki Tokuhara has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7056393Abstract: A method of making a sintered body for a rare earth magnet includes the steps of (a) preparing a first coarse powder by coarsely pulverizing a rare earth alloy sintered body by a hydrogen pulverization process, (b) preparing a first fine powder by finely pulverizing the first coarse powder, (c) preparing a second fine powder by pulverizing an alloy block of a rare earth alloy material, and (d) sintering a mixed powder including the first and second fine powders. The first and second fine powders each includes a main phase represented by (LR1-xHRx)2T14A, where T is Fe and/or at least one non-Fe transition metal element; A is boron and/or carbon; LR is at least one light rare earth element; HR is at least one heavy rare earth element; and 0?x<1.Type: GrantFiled: May 28, 2002Date of Patent: June 6, 2006Assignee: Neomax, Co., Ltd.Inventors: Koki Tokuhara, Hitoshi Morimoto
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Patent number: 6969244Abstract: The present invention aims to prevent heating and ignition of a material powder of a rare-earth alloy while reducing the oxygen content thereof so as to improve the magnetic properties of the rare-earth magnet. A rare-earth alloy powder is compacted by using a powder compacting apparatus including: an airtight container capable of storing a rare-earth alloy powder therein; an airtight feeder box moved between a powder-filling position and a retracted position; and an airtight powder supply device capable of supplying the rare-earth alloy powder from the container into the feeder box without exposing the rare-earth alloy powder to the atmospheric air.Type: GrantFiled: August 15, 2002Date of Patent: November 29, 2005Assignee: Neomax Co., Ltd.Inventors: Futoshi Kuniyoshi, Koki Tokuhara, Kunitoshi Kanno, Hitoshi Morimoto, Tomoiku Ohtani, Ryoji Ono
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Patent number: 6696015Abstract: The method for producing a rare-earth sintered magnet of the present invention includes the steps of: compacting alloy powder for the rare-earth sintered magnet to form a green compact; loading the green compact into a case having a structure restricting a path through which gas flows between the outside and inside of the case, and placing a gas absorbent at least near the path; and sintering the green compact by heating the case including the green compact inside in a decompressed atmosphere.Type: GrantFiled: May 2, 2001Date of Patent: February 24, 2004Assignee: Sumitomo Special Metals Co., Ltd.Inventors: Koki Tokuhara, Akiyasu Oota, Tsuyoshi Wada, Katsumi Okayama, Tomoiku Ohtani, Kunitoshi Kanno
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Publication number: 20040020563Abstract: A method of making a sintered body for a rare earth magnet includes the steps of (a) preparing a first coarse powder by coarsely pulverizing a rare earth alloy sintered body by a hydrogen pulverization process, (b) preparing a first fine powder by finely pulverizing the first coarse powder, (c) preparing a second fine powder by pulverizing an alloy block of a rare earth alloy material, and (d) sintering a mixed powder including the first and second fine powders. The first and second fine powders each includes a main phase represented by (LR1-xHRx)2T14A, where T is Fe and/or at least one non-Fe transition metal element; A is boron and/or carbon; LR is at least one light rare earth element; HR is at least one heavy rare earth element; and 0≦x<1.Type: ApplicationFiled: March 20, 2003Publication date: February 5, 2004Inventors: Koki Tokuhara, Hitoshi Morimoto
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Patent number: 6511631Abstract: The present invention aims to prevent heating and ignition of a material powder of a rare-earth alloy while reducing the oxygen content thereof so as to improve the magnetic properties of the rare-earth magnet. A rare-earth alloy powder is compacted by using a powder compacting apparatus including: an airtight container capable of storing a rare-earth alloy powder therein; an airtight feeder box moved between a powder-filling position and a retracted position; and an airtight powder supply device capable of supplying the rare-earth alloy powder from the container into the feeder box without exposing the rare-earth alloy powder to the atmospheric air.Type: GrantFiled: April 20, 2001Date of Patent: January 28, 2003Assignee: Sumitomo Special Metals Co., Ltd.Inventors: Futoshi Kuniyoshi, Koki Tokuhara, Kunitoshi Kanno, Hitoshi Morimoto, Tomoiku Ohtani, Ryoji Ono
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Publication number: 20020197180Abstract: A green compact of a rare earth alloy magnetic powder is made by pressing the powder. The powder is pressed within an air environment that has a temperature controlled at 30° C. or less and a relative humidity controlled at 65% or less.Type: ApplicationFiled: August 21, 2002Publication date: December 26, 2002Applicant: SUMITOMO SPECIAL METALS CO., LTD.Inventors: Koki Tokuhara, Shuhei Okumura, Akiyasu Oota
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Publication number: 20020185792Abstract: The present invention aims to prevent heating and ignition of a material powder of a rare-earth alloy while reducing the oxygen content thereof so as to improve the magnetic properties of the rare-earth magnet. A rare-earth alloy powder is compacted by using a powder compacting apparatus including: an airtight container capable of storing a rare-earth alloy powder therein; an airtight feeder box moved between a powder-filling position and a retracted position; and an airtight powder supply device capable of supplying the rare-earth alloy powder from the container into the feeder box without exposing the rare-earth alloy powder to the atmospheric air.Type: ApplicationFiled: August 15, 2002Publication date: December 12, 2002Applicant: SUMITOMO SPECIAL METALS CO., LTD.Inventors: Futoshi Kuniyoshi, Koki Tokuhara, Kunitoshi Kanno, Hitoshi Morimoto, Tomoiku Ohtani, Ryoji Ono
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Patent number: 6461565Abstract: A green compact of a rare earth alloy magnetic powder is made by pressing the powder. The powder is pressed within an air environment that has a temperature controlled at 30° C. or less and a relative humidity controlled at 65% or less.Type: GrantFiled: March 8, 2001Date of Patent: October 8, 2002Assignee: Sumitomo Special Metals Co., Ltd.Inventors: Koki Tokuhara, Shuhei Okumura, Akiyasu Oota
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Publication number: 20020012600Abstract: The method for producing a rare-earth sintered magnet of the present invention includes the steps of: compacting alloy powder for the rare-earth sintered magnet to form a green compact; loading the green compact into a case having a structure restricting a path through which gas flows between the outside and inside of the case, and placing a gas absorbent at least near the path; and sintering the green compact by heating the case including the green compact inside in a decompressed atmosphere.Type: ApplicationFiled: May 2, 2001Publication date: January 31, 2002Inventors: Koki Tokuhara, Akiyasu Oota, Tsuyoshi Wada, Katsumi Okayama, Tomoiku Ohtani, Kunitoshi Kanno
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Publication number: 20020006347Abstract: A green compact of a rare earth alloy magnetic powder is made by pressing the powder. The powder is pressed within an air environment that has a temperature controlled at 30° C. or less and a relative humidity controlled at 65% or less.Type: ApplicationFiled: March 8, 2001Publication date: January 17, 2002Inventors: Koki Tokuhara, Shuhei Okumura, Akiyasu Oota
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Publication number: 20020001534Abstract: The present invention aims to prevent heating and ignition of a material powder of a rare-earth alloy while reducing the oxygen content thereof so as to improve the magnetic properties of the rare-earth magnet. A rare-earth alloy powder is compacted by using a powder compacting apparatus including: an airtight container capable of storing a rare-earth alloy powder therein; an airtight feeder box moved between a powder-filling position and a retracted position; and an airtight powder supply device capable of supplying the rare-earth alloy powder from the container into the feeder box without exposing the rare-earth alloy powder to the atmospheric air.Type: ApplicationFiled: April 20, 2001Publication date: January 3, 2002Inventors: Futoshi Kuniyoshi, Koki Tokuhara, Kunitoshi Kanno, Hitoshi Morimoto, Tomoiku Ohtani, Ryoji Ono
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Patent number: 6331214Abstract: Its basic means is a monolithically bonded construct prepared by monolithically bonding together a rare-earth magnet 2 and a an alloy material that is a high melting point metal or a high specific-tenacity material through the solid phase diffusion bonding by the hot isostatic pressing treatment, and a monolithically bonded construct with an interposal of a thin layer of the high melting point metal between a rare-earth magnet 2 and an alloy material 3, 4 that is a high specific-tenacity material.Type: GrantFiled: September 21, 1998Date of Patent: December 18, 2001Assignees: Kabushiki Kaisha Meidensha, Sumitomo Special Metals Co., LTDInventors: Masaki Koga, Nobutaka Suzuki, Hitoshi Saitoh, Kenshiro Oyamada, Koki Tokuhara, Shuji Mino, Naoyuki Ishigaki, Hitoshi Yamamoto
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Patent number: 6247660Abstract: A case for hydrogen-pulverizing a rare earth metal-based magnetic material is disclosed. The case includes a case body which is formed of a material having a heat conductivity of 1 W/cm·deg or more. At least one heat-transferring/releasing member is mounted in the case body and formed of a material having a heat conductivity of 1 W/cm·deg or more. The magnetic material is accommodated in the case and subjected to a hydrogen pulverization with hydrogen occluded in the magnetic material.Type: GrantFiled: October 6, 1999Date of Patent: June 19, 2001Assignee: Sumitomo Special Metals Co., Ltd.Inventors: Yasuhiko Imai, Koki Tokuhara, Katsumi Okayama, Akiyasu Oota, Akihito Tsujimoto
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Patent number: 5788782Abstract: It is an object of the present invention to provide R-Fe-B permanent magnet materials having a good oxidation resistance and magnetic characteristics, and a process of producing the same capable of pulverizing efficiently, whereby an R-Fe-B molten alloy having a specific composition is casted into a cast piece having a specific plate thickness and a structure, in which an R-rich phase is finely separated below 5 .mu.m, by a strip casting process, the cast piece is subjected to a Hydrogenation for spontaneous decay, and thereafter, an alloy powder is dehydrogenated and stabilized for pulverization so as to fractionize crystal grains of a main phase constituting an alloy ingot, thereby the powder having a uniform grain distribution can be produced at an efficiency of about twice as much as the conventional process, and the R-rich phase and an R.sub.2 Fe.sub.Type: GrantFiled: August 9, 1995Date of Patent: August 4, 1998Assignee: Sumitomo Special Metals Co., Ltd.Inventors: Yuji Kaneko, Naoyuki Ishigaki, Koki Tokuhara
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Patent number: 5387291Abstract: A process for producing a starting powder material for use in the fabrication of high performance R--Fe--B permanent magnets comprising an R.sub.2 Fe.sub.14 B compound as the principal phase, which is characterized by adding 70% by weight or less of a specified alloy powder for adjusting the composition comprising an R.sub.2 Fe.sub.17 compound to a specified principal phase R--Fe--B alloy powder comprising an R.sub.2 Fe.sub.14 B compound as the principal phase. This process enables production of a starting alloy powder material considerably reduced in contents of the unfavorable B-rich and R-rich phases which impair the magnetic properties of the final magnet, because the starting powder blend allows the B-rich and R-rich compounds in the principal phase alloy powder to react with the R.sub.2 Fe.sub.17 compound being incorporated in the alloy powder for adjusting the composition.Type: GrantFiled: March 17, 1993Date of Patent: February 7, 1995Assignee: Sumitomo Special Metals Co., Ltd.Inventors: Yuji Kaneko, Koki Tokuhara