Patents by Inventor Tomotsuna Kamijo
Tomotsuna Kamijo 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: 9922758Abstract: A powder for a powder magnetic core, being composed of iron-base soft magnetic powder particles which each have a phosphoric acid-based chemical conversion coating on the surface. In this powder, the maximum thickness of the phosphoric acid-based chemical conversion coating is 20 to 200 nm, and recessed portions are formed on the surface of the chemical conversion coating with the total area of openings of the recessed portions being 0.5 to 50% by area relative to the total area of the observation visual fields, as determined by observing ten or more parts of the surface of the phosphoric acid-based chemical conversion coating through a scanning electron microscope with a magnification of 10000× or more.Type: GrantFiled: July 9, 2013Date of Patent: March 20, 2018Assignee: Kobe Steel, Ltd.Inventors: Wataru Urushihara, Mikako Takeda, Mamoru Hosokawa, Hirofumi Hojo, Tomotsuna Kamijo
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Patent number: 9583261Abstract: A powder magnetic core which exhibits a high compact density and a reduced iron loss can be obtained by compacting a soft magnetic powder in which the mass ratio of soft magnetic powder particles that pass through a filter having an opening of 75 ?m is 95 mass % or higher relative to the whole amount of the soft magnetic powder and which has a mean strain of less than 0.100%.Type: GrantFiled: August 26, 2013Date of Patent: February 28, 2017Assignee: Kobe Steel, Ltd.Inventors: Hiroyuki Mitani, Takeo Miyamura, Hirofumi Hojo, Tomotsuna Kamijo
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Patent number: 9472328Abstract: Disclosed is an iron-based soft magnetic powder for dust core use, which includes an iron-based soft magnetic matrix powder and a phosphate conversion coating on a surface of the matrix powder. The phosphate conversion coating contains nickel element and has an aluminum content of equal to or less than that in the matrix powder. The iron-based soft magnetic powder has such excellent heat resistance as to maintain electrical insulation at satisfactory level even after subjected to a high-temperature heat treatment.Type: GrantFiled: June 15, 2012Date of Patent: October 18, 2016Assignee: Kobe Steel, Ltd.Inventors: Mamoru Hosokawa, Wataru Urushihara, Takeshi Ohwaki, Tomotsuna Kamijo, Hirofumi Hojo
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Patent number: 9275779Abstract: Provided is an iron-based soft magnetic powder for dust core having a less coercive force, which is obtained by specifying the amount of inclusions in the iron-based powder for dust core, and at the same time, capable of decreasing the coercive force of a dust core produced using the iron-based soft magnetic powder. The iron-based soft magnetic powder for dust core is characterized by that when the cross-section of the iron-based soft magnetic powder particle is observed with a scanning electron microscope, the number of inclusions having an equivalent circle diameter from 0.1 to 3 ?m is 1×104 pieces/mm2 or less and the number of inclusions having an equivalent circle diameter exceeding 3 ?m is 10 pieces/mm2 or less.Type: GrantFiled: November 29, 2011Date of Patent: March 1, 2016Assignee: Kobe Steel, Ltd.Inventors: Hirofumi Hojo, Masamichi Chiba, Hiroyuki Mitani, Nobuaki Akagi, Tomotsuna Kamijo
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Publication number: 20150228387Abstract: A powder for a powder magnetic core, being composed of iron-base soft magnetic powder particles which each have a phosphoric acid-based chemical conversion coating on the surface. In this powder, the maximum thickness of the phosphoric acid-based chemical conversion coating is 20 to 200 nm, and recessed portions are formed on the surface of the chemical conversion coating with the total area of openings of the recessed portions being 0.5 to 50% by area relative to the total area of the observation visual fields, as determined by observing ten or more parts of the surface of the phosphoric acid-based chemical conversion coating through a scanning electron microscope with a magnification of 10000× or more.Type: ApplicationFiled: July 9, 2013Publication date: August 13, 2015Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Wataru Urushihara, Mikako Takeda, Mamoru Hosokawa, Hirofumi Hojo, Tomotsuna Kamijo
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Publication number: 20150187493Abstract: A powder magnetic core which exhibits a high compact density and a reduced iron loss can be obtained by compacting a soft magnetic powder in which the mass ratio of soft magnetic powder particles that pass through a filter having an opening of 75 ?m is 95 mass % or higher relative to the whole amount of the soft magnetic powder and which has a mean strain of less than 0.100%.Type: ApplicationFiled: August 26, 2013Publication date: July 2, 2015Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Hiroyuki Mitani, Takeo Miyamura, Hirofumi Hojo, Tomotsuna Kamijo
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Publication number: 20140183402Abstract: Disclosed is an iron-based soft magnetic powder for dust core use, which includes an iron-based soft magnetic matrix powder and a phosphate conversion coating on a surface of the matrix powder. The phosphate conversion coating contains nickel element and has an aluminum content of equal to or less than that in the matrix powder. The iron-based soft magnetic powder has such excellent heat resistance as to maintain electrical insulation at satisfactory level even after subjected to a high-temperature heat treatment.Type: ApplicationFiled: June 15, 2012Publication date: July 3, 2014Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Mamoru Hosokawa, Wataru Urushihara, Takeshi Ohwaki, Tomotsuna Kamijo, Hirofumi Hojo
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Patent number: 8323422Abstract: Provided is a dust core excellent in flux density, iron loss, and mechanical strength. A production process of a dust core according to the invention includes a step of compacting a mixture obtained by mixing an iron-based soft magnetic powder for powder compact having a phosphate conversion coating film on the surface of an iron-based soft magnetic powder with a lubricant to obtain a powder compact, a heat treatment step of heating the resulting powder compact at 550° C. or more but not more than 650° C. in an inert atmosphere, and a heat treatment step of heating the heat-treated powder compact at 420° C. or more but not more than 530° C. in an oxidizing atmosphere.Type: GrantFiled: November 22, 2011Date of Patent: December 4, 2012Assignee: Kobe Steel, Ltd.Inventors: Takeshi Ohwaki, Hiroyuki Mitani, Hirofumi Hojo, Tomotsuna Kamijo
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Publication number: 20120286909Abstract: A method produces a dust core by molding a mixture through compression molding to give a powder compact, the mixture containing an oxygen-source-releasable compound and an iron-based soft magnetic powder for powder compacts including an iron-based soft magnetic matrix powder and an insulating coating film present on the surface of the matrix powder; and heating the powder compact to oxidize at least the surface of the iron-based soft magnetic matrix powder by the action of the oxygen-source-releasable compound. The resulting dust core excels not only in mechanical strength but also in resistivity (insulation).Type: ApplicationFiled: March 30, 2012Publication date: November 15, 2012Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Takeshi OHWAKI, Hiroyuki Mitani, Hirofumi Hojo, Tomotsuna Kamijo, Akihiko Tatsumi, Wataru Urushihara, Mikako Takeda, Mamoru Hosokawa
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Publication number: 20120164453Abstract: Provided is an iron-based soft magnetic powder for dust core having a less coercive force, which is obtained by specifying the amount of inclusions in the iron-based powder for dust core, and at the same time, capable of decreasing the coercive force of a dust core produced using the iron-based soft magnetic powder. The iron-based soft magnetic powder for dust core is characterized by that when the cross-section of the iron-based soft magnetic powder particle is observed with a scanning electron microscope, the number of inclusions having an equivalent circle diameter from 0.1 to 3 ?m is 1×104 pieces/mm2 or less and the number of inclusions having an equivalent circle diameter exceeding 3 ?m is 10 pieces/mm2 or less.Type: ApplicationFiled: November 29, 2011Publication date: June 28, 2012Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Hirofumi HOJO, Masamichi Chiba, Hiroyuki Mitani, Nobuaki Akagi, Tomotsuna Kamijo
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Publication number: 20120154083Abstract: Provided is a dust core excellent in flux density, iron loss, and mechanical strength. A production process of a dust core according to the invention includes a step of compacting a mixture obtained by mixing an iron-based soft magnetic powder for powder compact having a phosphate conversion coating film on the surface of an iron-based soft magnetic powder with a lubricant to obtain a powder compact, a heat treatment step of heating the resulting powder compact at 550° C. or more but not more than 650° C. in an inert atmosphere, and a heat treatment step of heating the heat-treated powder compact at 420° C. or more but not more than 530° C. in an oxidizing atmosphere.Type: ApplicationFiled: November 22, 2011Publication date: June 21, 2012Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Takeshi Ohwaki, Hiroyuki Mitani, Hirofumi Hojo, Tomotsuna Kamijo