Patents by Inventor Kotobu Nagai

Kotobu Nagai 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).

  • Publication number: 20190099829
    Abstract: A method for spot-welding metallic materials includes: sandwiching the metallic materials with a pair of electrodes; a pre-heating step for pre-heating a region different from a given region which should be welded by applying electric power having a high frequency to the pair of electrodes; and a welding step for spot-welding a given region of the metallic materials by applying electric power for welding to the pair of electrodes. The heating time in the pre-heating step and that in the welding step are independently controlled.
    Type: Application
    Filed: November 30, 2018
    Publication date: April 4, 2019
    Applicants: NETUREN CO., LTD., NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Takahiko KANAI, Munehisa HATTA, Fumiaki IKUTA, Kazuhiro KAWASAKI, Eizaburo NAKANISHI, Tsuyoshi YOSHIDA, Kotobu NAGAI, Masao HAYAKAWA, Takehiko ITAGAKI
  • Patent number: 10189112
    Abstract: A welding equipment for metallic materials capable of performing heat treatment such as tempering based on partial heating in spot welding is provided. The welding equipment sandwiches metallic materials with a pair of electrodes, and heats different regions of the metallic materials by energization, with the pair of electrodes maintained at the same position with respect to the metallic materials. The welding equipment includes a first heating means connected to the pair of electrodes for heating and welding the internal region of the circle defined by projecting the cross-sectional area of the axis of the electrodes on the metallic materials by applying power having a low first frequency, a second heating means for heating a ring-shaped region along the circle by applying power having a second frequency that is higher than the first frequency, and an energization control unit for independently controlling the first and the second heating means.
    Type: Grant
    Filed: June 12, 2015
    Date of Patent: January 29, 2019
    Assignees: NETUREN CO., LTD., NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Takahiko Kanai, Munehisa Hatta, Fumiaki Ikuta, Kazuhiro Kawasaki, Eizaburo Nakanishi, Tsuyoshi Yoshida, Kotobu Nagai, Masao Hayakawa, Takehiko Itagaki
  • Patent number: 9498840
    Abstract: A welding structural part 1 is manufactured by overlapping the surfaces of steel sheets 2, and forming a weld zone by spot welding. The weld zone 3 includes: a weld nugget 4; and a heat affected zone 5 surrounding the weld nugget 4, wherein the hardness in the weld zone increases along an exterior region 6 of the heat affected zone 5 toward the heat affected zone 5, and then decreases along the heat affected zone 5 toward the central region of the weld nugget 4. In the boundary region between the weld nugget 4 and the heat affected zone 5, the weld nugget 4 may have a convex portion 4A bulging into the heat affected zone 5 along the overlapped portion. The steel sheets 2 contain carbon in 0.15 mass % or more.
    Type: Grant
    Filed: July 30, 2010
    Date of Patent: November 22, 2016
    Assignees: NETUREN CO., LTD., NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Takahiko Kanai, Munehisa Hatta, Fumiaki Ikuta, Kazuhiro Kawasaki, Eizaburou Nakanishi, Masayuki Miyake, Kotobu Nagai, Masao Hayakawa, Takehiko Itagaki
  • Publication number: 20150306696
    Abstract: A welding equipment for metallic materials capable of performing heat treatment such as tempering based on partial heating in spot welding is provided. The welding equipment sandwiches metallic materials with a pair of electrodes, and heats different regions of the metallic materials by energization, with the pair of electrodes maintained at the same position with respect to the metallic materials. The welding equipment includes a first heating means connected to the pair of electrodes for heating and welding the internal region of the circle defined by projecting the cross-sectional area of the axis of the electrodes on the metallic materials by applying power having a low first frequency, a second heating means for heating a ring-shaped region along the circle by applying power having a second frequency that is higher than the first frequency, and an energization control unit for independently controlling the first and the second heating means.
    Type: Application
    Filed: June 12, 2015
    Publication date: October 29, 2015
    Applicants: NATIONAL INSTITUTE FOR MATERIALS SCIENCE, NETUREN CO., LTD.
    Inventors: Takahiko KANAI, Munehisa HATTA, Fumiaki IKUTA, Kazuhiro KAWASAKI, Eizaburo NAKANISHI, Tsuyoshi YOSHIDA, Kotobu NAGAI, Masao HAYAKAWA, Takehiko ITAGAKI
  • Patent number: 9079266
    Abstract: A welding equipment for metallic materials capable of performing heat treatment such as tempering based on partial heating in spot welding is provided. The welding equipment 1 sandwiches metallic materials 9 with a pair of electrodes 4, 4, and heats different regions of the metallic materials 9 by energization, with the pair of electrodes 4, 4 maintained at the same position with respect to the metallic materials 9. The welding equipment includes a first heating means 6 connected to the pair of electrodes 4, 4 for heating and welding the internal region of the circle defined by projecting the cross-sectional area of the axis of the electrodes on the metallic materials by applying power having a low first frequency, a second heating means 8 for heating a ring-shaped region along the circle by applying power having a second frequency that is higher than the first frequency, and an energization control unit 10 for independently controlling the first and the second heating means 6, 8.
    Type: Grant
    Filed: September 30, 2009
    Date of Patent: July 14, 2015
    Assignees: NETUREN CO., LTD., NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Takahiko Kanai, Munehisa Hatta, Fumiaki Ikuta, Kazuhiro Kawasaki, Eizaburo Nakanishi, Tsuyoshi Yoshida, Kotobu Nagai, Masao Hayakawa, Takehiko Itagaki
  • Patent number: 8932416
    Abstract: A high-strength die-quenched part 1 is formed by heating a high-strength steel sheet 11 up to an austenite region, hot stamping and cooling inside a mold, and its microstructure has the martensite wherein carbide particles 2 are finely dispersed over an entire region including prior-austenite grain boundaries. It is desirable that the prior-austenite grain size in the microstructure of the high-strength steel sheet, which is a base material, be 10 ?m or smaller. The high-strength die-quenched part has high-strength and high-ductility thanks to its martensite.
    Type: Grant
    Filed: May 26, 2010
    Date of Patent: January 13, 2015
    Assignees: Nissan Motor Co., Ltd., National Institute for Materials Science, Neturen Co., Ltd
    Inventors: Eizaburou Nakanishi, Masayuki Miyake, Kotobu Nagai, Masao Hayakawa, Takehito Itagaki, Takahiko Kanai, Munehisa Hatta, Kazuhiro Kawasaki
  • Publication number: 20120129006
    Abstract: A welding structural part 1 is manufactured by overlapping the surfaces of steel sheets 2, and forming a weld zone by spot welding. The weld zone 3 includes: a weld nugget 4; and a heat affected zone 5 surrounding the weld nugget 4, wherein the hardness in the weld zone increases along an exterior region 6 of the heat affected zone 5 toward the heat affected zone 5, and then decreases along the heat affected zone 5 toward the central region of the weld nugget 4. In the boundary region between the weld nugget 4 and the heat affected zone 5, the weld nugget 4 may have a convex portion 4A bulging into the heat affected zone 5 along the overlapped portion. The steel sheets 2 contain carbon in 0.15 mass % or more.
    Type: Application
    Filed: July 30, 2010
    Publication date: May 24, 2012
    Applicants: NETUREN CO., LTD., NATIONAL INSTITUTE FOR MATERIALS SCIENCE, NISSAN MOTOR CO., LTD.
    Inventors: Takahiko Kanai, Munehisa Hatta, Fumiaki Ikuta, Kazuhiro Kawasaki, Eizaburou Nakanishi, Masayuki Miyake, Kotobu Nagai, Masao Hayakawa, Takehiko Itagaki
  • Publication number: 20120118440
    Abstract: A high-strength die-quenched part 1 is formed by heating a high-strength steel sheet 11 up to an austenite region, hot stamping and cooling inside a mold, and its microstructure has the martensite wherein carbide particles 2 are finely dispersed over an entire region including prior-austenite grain boundaries. It is desirable that the prior-austenite grain size in the microstructure of the high-strength steel sheet, which is a base material, be 10 ?m or smaller. The high-strength die-quenched part has high-strength and high-ductility thanks to its martensite.
    Type: Application
    Filed: May 26, 2010
    Publication date: May 17, 2012
    Applicants: NISSAN MOTOR CO., LTD., NETUREN CO., LTD., NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Eizaburou Nakanishi, Masayuki Miyake, Kotobu Nagai, Masao Hayakawa, Takehito Itagaki, Takahiko Kanai, Munehisa Hatta, Kazuhiro Kawasaki
  • Publication number: 20110303655
    Abstract: A welding equipment for metallic materials capable of performing heat treatment such as tempering based on partial heating in spot welding is provided. The welding equipment 1 sandwiches metallic materials 9 with a pair of electrodes 4, 4, and heats different regions of the metallic materials 9 by energization, with the pair of electrodes 4, 4 maintained at the same position with respect to the metallic materials 9. The welding equipment includes a first heating means 6 connected to the pair of electrodes 4, 4 for heating and welding the internal region of the circle defined by projecting the cross-sectional area of the axis of the electrodes on the metallic materials by applying power having a low first frequency, a second heating means 8 for heating a ring-shaped region along the circle by applying power having a second frequency that is higher than the first frequency, and an energization control unit 10 for independently controlling the first and the second heating means 6, 8.
    Type: Application
    Filed: September 30, 2009
    Publication date: December 15, 2011
    Applicants: NATIONAL INSTITUTE FOR MATERIALS SCIENCE, NETUREN CO., LTD.
    Inventors: Takahiko Kanai, Munehisa Hatta, Fumiaki Ikuta, Kazuhiro Kawasaki, Eizaburo Nakanishi, Tsuyoshi Yoshida, Kotobu Nagai, Masao Hayakawa, Takehiko Itagaki
  • Patent number: 8070888
    Abstract: A wire rod or a steel wire of a bamboo nano-structure, whose mean grain diameter in a C-direction section is 200 nm or smaller, is prepared by applying a hot or warm working and additionally applying a cold working to a steel and next, by performing a forging, by a tool or a die such as cold pressure production, to a section, of a desired, limited site, other than a section parallel to an L-direction, an equiaxed nano-structure, whose mean grain diameter is 200 nm or smaller, is formed in this site. As a typical example of a formed article, there is enumerated a high strength micro screw in which a shaft outer diameter is 1.6 mm or smaller, a surface layer part of a head part recess has equiaxed nano-structure and a hardness Hv?300, and a screw main body portion has bamboo nano-structure and a hardness Hv?250.
    Type: Grant
    Filed: February 28, 2006
    Date of Patent: December 6, 2011
    Assignee: National Institute for Materials Science
    Inventors: Shiro Torizuka, Eijrio Muramatsu, Kotobu Nagai
  • Publication number: 20110083775
    Abstract: A tough high strength heavy wall steel material having superior weldability is provided, said steel material has a diameter or a side 5 mm or more in length, and comprises oxides 1 ?m or less in particle diameter homogeneously dispersed at a dispersion density in a range of from 10,000 to 100,000 particles/mm2 and uniform ferrite grains 2 ?m or less in grain diameter formed over the entire plane making a right angle with respect to the rolling direction.
    Type: Application
    Filed: December 15, 2010
    Publication date: April 14, 2011
    Inventors: Hiroshi Nakajima, Shiro Torizuka, Kaneaki Tsuzaki, Kotobu Nagai
  • Publication number: 20100173716
    Abstract: A formed product, characterized in that it is produced by using, as a material, a steel having an ultra fine structure comprising ferrite grains having an average grain diameter of 3 ?m or less and by a method comprising only a forming step and including none of refining steps; and a method for producting the above formed product with ease. The formed product contains no alloying element and has been subjected to no refining step, and has been imparted with high strength and high toughness by the above ultra fine structure.
    Type: Application
    Filed: July 21, 2009
    Publication date: July 8, 2010
    Inventors: Shiro Torizuka, Kotobu Nagai, Eijiro Muramatsu, Yoshiyuki Suzuki
  • Patent number: 7727343
    Abstract: The invention presents a new warm control rolling method, in consideration of processing heat generation, as a method of stably manufacturing ultrafine crystal steel of 3 microns to 1 micron or less, without any limitation in pass interval or strain speed, being a rolling method of manufacturing steel mainly composed of fine ferrite particle texture with average ferrite grain size of 3 ?m or less, in which, in the rolling process of one pass or more wherein the rolling temperature range is a temperature region of 350° C. to 800° C., the material temperature upon start of rolling of each rolling process does not exceed the maximum temperature of 800° C., and the material temperature during rolling and right after final rolling (within 1 second) is not lower than 350° C., temperature Tx-out right after rolling in each rolling process (within 1 second) is not higher than the temperature that is higher than rolling entry temperature Tx-in by 100° C.
    Type: Grant
    Filed: May 20, 2004
    Date of Patent: June 1, 2010
    Assignee: National Institute for Materials Science
    Inventors: Shiro Torizuka, Kotobu Nagai
  • Publication number: 20100051144
    Abstract: There are provided an excellent cold-workability exhibiting high-strength steel wire or steel bar, or high-strength shaped article and a process for producing them. In particular, there is provided a process comprising carrying out hot working at 350 to 800° C. of a steel ingot, cast slab, steel slab or steel semifinished product having a C content of not greater than the solid solution limit of carbon of ferrite phase at Ae1 point and not greater than 0.010 mass % and being free of any cementite, or having a C content of >0.01 to 0.45 mass % to thereby obtain a material whose average crystal grain diameter in a cross section perpendicular to the longitudinal direction is ?3 ?m, and thereafter carrying out cold working of the material to thereby attain formation of a ferrite structure whose average crystal grain diameter in a cross section perpendicular to the longitudinal direction is ?500 nm.
    Type: Application
    Filed: September 9, 2009
    Publication date: March 4, 2010
    Inventors: Shiro Torizuka, Eijiro Muramatsu, Kotobu Nagai
  • Patent number: 7647804
    Abstract: A method of rolling a material in two more continuous passes is disclosed. The method includes rolling the material with a flattened-shaped caliber in a first pass, and subsequently rolling with a square-shaped caliber in a second pass. The rolling is performed with a first pass caliber having a flattened shape, wherein the ratio of the length (2A01) of minor axis of the first pass caliber to an initial width (2A0) is (A01/A0)?0.75; and a second pass caliber, wherein the ratio of a diagonal dimension (2AS1) of the second pass caliber to the length (2B1) of the major axis of the material after the first pass is (AS1/B1)?0.75 to introduce the large strain into the material.
    Type: Grant
    Filed: May 20, 2004
    Date of Patent: January 19, 2010
    Assignee: National Institute for Materials Science
    Inventors: Tadanobu Inoue, Shiro Torizuka, Eijiro Muramatsu, Kotobu Nagai
  • Publication number: 20090277539
    Abstract: There are provided a steel for warm working, to be subjected to warm working as various structures, components of cars, and the like, a warm working method thereof, and a steel material and a steel component obtainable from the warm working method. [Solving Means] A steel is to have a particle dispersion type fiber structure formed in the matrix by warm working. The steel is characterized in that the total amount of the dispersed second-phase particles at room temperature is 7×10?3 or more in terms of volume fraction, and the Vickers hardness (HV) is equal to or larger than the hardness H of the following equation (2): H=(5.2?1.2×10?4?)×102??(2) when the steel is subjected to any of annealing, tempering, and aging treatments in the as-unworked state under conditions such that a parameter ? expressed by the following equation (1): ?=T(log t+20)(T; temperature(K), t; time(hr))??(1) is 1.4×104 or more in a prescribed temperature range of 350° C. or more and Ac1 point or less.
    Type: Application
    Filed: November 21, 2006
    Publication date: November 12, 2009
    Inventors: Yuuji Kimura, Tadanobu Inoue, Kaneaki Tsuzaki, Kotobu Nagai
  • Publication number: 20090236015
    Abstract: There is provided an ultrahigh strength steel sheet containing 0.10 to 0.40 mass % of C, 0.01 to 3.5 mass % of Cr, at least one selected from the group consisting of 0.10 to 2.0 mass % of Mo, 0.20 to 1.5 mass % of W, 0.002 to 1.0 mass % of V, 0.002 to 1.0 mass % of Ti and 0.005 to 1.0 mass % of Nb, 0.02 mass % or less of P and 0.01 mass % or less of S as impurities and the balance being Fe and unavoidable impurities based on the total mass of the steel sheet and having a base structure of lower bainite, a prior austenite grain size of 30 ?m or smaller and a tensile strength of 980 MPa or higher. There is also provided an automotive strength part using the ultrahigh strength steel sheet.
    Type: Application
    Filed: April 3, 2007
    Publication date: September 24, 2009
    Applicant: NISSAN MOTOR CO., LTD.
    Inventors: Hideyuki Sasaoka, Masamoto Ono, Eizaburou Nakanishi, Yoshio Okada, Tadanobu Inoue, Yuuji Kimura, Kotobu Nagai
  • Publication number: 20090185943
    Abstract: In a steel plate having tensile strength of 1 GPa or more at the normal temperature, the steel plate is made, stress decrement (SD) after uniform elongation in the stress-strain diagram obtained by using a tabular specimen of which is not less than 1.8×102 MPa, yield ratio (YR) of which is preferably not lower than 0.7, further preferably not lower than 0.8, and matrix structure of which is composed of martensite or bainite, or mixture of martensite and bainite substantially without proeutectoid ferrite, whereby the tough-ductility is improved on a practically utilizable level, and the steel plate becomes possible to be supplied in large quantities by winding up into a coil.
    Type: Application
    Filed: April 12, 2007
    Publication date: July 23, 2009
    Applicant: National Institute for Materials Science
    Inventors: Tadanobu Inoue, Yuuji Kimura, Kotobu Nagai
  • Publication number: 20080210351
    Abstract: A formed product, characterized in that it is produced by using, as a material, a steel having an ultra fine structure comprising ferrite grains having an average grain diameter of 3 ?m or less and by a method comprising only a forming step and including none of refining steps; and a method for producting the above formed product with ease. The formed product contains no alloying element and has been subjected to no refining step, and has been imparted with high strength and high toughness by the above ultra fine structure.
    Type: Application
    Filed: April 8, 2008
    Publication date: September 4, 2008
    Inventors: Shiro TORIZUKA, Kotobu NAGAI, Eijiro MURAMATSU, Yoshiyuki SUZUKI
  • Publication number: 20080135140
    Abstract: A wire rod or a steel wire of a bamboonano-stricture, whose mean grain diameter in a C-direction section is 200 nm or smaller, is prepared by applying a hot or warm working and additionally applying a cold working to a steel and next, by performing a forging, by a tool or a die such as cold pressure production, to a section, of a desired, limited site, other than a section parallel to an L-direction, an equiaxed nano-structure, whose mean grain diameter is 200 nm or smaller, is formed in this site. As a typical example of a formed article, there is enumerated a screw, and there is enumerated a high strength micro screw in which a shaft outer diameter is 1.6 mm or smaller, a surface layer part of a head part recess is the equiaxed nano-structure and a hardness HV?300, and a screw main body portion is the bamboo nano-structure and a hardness Hv?250. A constituent composition is a carbon steel of C<0.02%, and a strengthening element may not be added especially.
    Type: Application
    Filed: February 28, 2006
    Publication date: June 12, 2008
    Inventors: Shiro Torizuka, Eijrio Muramatsu, Kotobu Nagai