Patents by Inventor Nobuaki Mitamura
Nobuaki Mitamura 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: 6165100Abstract: At least one of input/output disks, a power roller and a cam disk of a toroidal type continuously variable transmission is formed of a high-cleanness steel in which a size of a maximum inclusion is estimated by the following extremum statistical process. In step S1, a plane including a central line of the high-cleanness steel is cut out in a direction of rolling of the high-cleanness steel. In step S2, a portion d of the cut-out cross-section, which is defined by 40% of a diameter D in the vicinity of the central line, is used as a to-be-tested surface. In step S3, a test reference area S.sub.0 is set at an area not less than 300 mm.sup.2 within the to-be-tested surface, and a root of an area of the maximum inclusion is measured five times or more. In step S4, a maximum inclusion distribution straight line is obtained. In step S5, the root, that is, the size of the area of the maximum inclusion within an estimation area S is estimated.Type: GrantFiled: November 6, 1998Date of Patent: December 26, 2000Assignees: NSK Ltd., Sanyo Special Steel Co., Ltd.Inventors: Nobuaki Mitamura, Tomonobu Yoshikawa, Yasuo Murakami
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Patent number: 6152605Abstract: A ball bearing in which races are well prevented from flaking in early stages under an environment using lubricating oil having a high traction coefficient so that a long life of the ball bearing is attained, while the cost of the bearing is reduced. The ball bearing has a plurality of balls disposed between a fixed race and a rotating race, and the ball bearing is used under an environment using lubricating oil having a traction coefficient of 0.07 or more under the conditions that a slip factor is 5% and a temperature is 40.degree. C. At least the groove radius of the rotating race is set to be in a range of from 0.53 Dw to 0.58 Dw both inclusive when Dw designates the diameter of balls. In addition, the hardness of the race is set to be in a range of from HRC 58 to HRC 64 both inclusive.Type: GrantFiled: August 24, 1999Date of Patent: November 28, 2000Assignee: NSK Ltd.Inventors: Hiromichi Takemura, Kazuo Sekino, Nobuaki Mitamura, Yasuo Murakami, Hiroshi Suzuki, Yoshitaka Hayashi
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Patent number: 6066068Abstract: A power roller bearing and input and output disks are made of a material containing 0.15 to 0.5 wt %, 0.15 to 1.5 wt %, and 0.1 to 1.5 wt % of C, Si, and Mo, respectively, and 9 ppm or less of oxygen. At least one component selected from the group consisting of the inner and outer rings and the input and output disks is subjected to carbonitriding, hardening, tempering and grinding, such that a finished surface hardness has a Vickers hardness of Hv720 or more and the hardness at a depth of Dx from the surface is Hv650 or more. The Dx is a critical equivalent stress generation position in a synthetic stress distribution and meets Dx=3.0 Zo to 5.0 Zo where Zo is a maximum dynamic shearing stress generation position from the surface.Type: GrantFiled: October 30, 1998Date of Patent: May 23, 2000Assignee: NSK, Ltd.Inventors: Hiromichi Takemura, Nobuaki Mitamura
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Patent number: 5989694Abstract: Disclosed is a rolling bearing comprising races and rolling elements, in which at least one of the races and the rolling elements has at least one of a carbide and a carbonitride precipitated in a surface layer thereof, inclusive of a cutting allowance, wherein the finished surface of at least one of the races and the rolling elements has a hardness of Hv600 to Hv700 at 300.degree. C. The rolling bearing has reliable wear resistance under severe conditions and thereby having an extended bearing life.Type: GrantFiled: June 17, 1997Date of Patent: November 23, 1999Assignee: NSK, Ltd.Inventors: Nobuaki Mitamura, Kazuo Sekino, Yasuo Murakami
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Patent number: 5958155Abstract: A substrate (2) is rotatably installed in a vacuum chamber (1) at an upper part thereof MgF.sub.2 granules (3) as a film source material are placed in a quartz boat (4) and mounted on a magnetron cathode (5). The magnetron cathode (5) is connected through a matching box (6) to a 13.56 MHz radio frequency power source (7). Cooling water (8) for holding the temperature of the magnetron cathode (5) constant flows against a lower face of the magnetron cathode (5). A side wall of the vacuum chamber (1) is provided with gas introduction ports (9), (10) for introducing gas in the vacuum chamber (1). A shutter (11) is placed between the magnetron cathode (5) and the substrate (2). This structure provides a process enabling forming a thin film at a high speed by sputtering, especially a high speed sputtering process enabling forming a thin fluoride film free of light absorption.Type: GrantFiled: July 18, 1996Date of Patent: September 28, 1999Assignee: Olympus Optical Co., Ltd.Inventors: Ken Kawamata, Nobuaki Mitamura
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Patent number: 5887015Abstract: A heater mechanism for a crystal pulling apparatus is disclosed. Electrodes made of copper or the like and disposed under a heater are connected to the heater via graphite members. A cover member is attached to each graphite member, so that the downwardly extending portion of the cover member surrounds the outer surface of the graphite member. Accordingly, a leak or splash of a melt is prevented from contacting the electrodes. The length of each graphite member is equal to or greater than the distance between the bottom surface of the heater and the top surface of a melt spill tray which distance is measured when the heater mechanism is raised The cover member is vertically slidable along the outer surface of each graphite member. Thus, even when a material melt leaks out from a crucible, the electrodes of the heater mechanism can be protected from a fusion damage or the like which would be otherwise caused by the leak of the melt.Type: GrantFiled: December 11, 1996Date of Patent: March 23, 1999Assignee: Shin-Etsu Handotai Co., Ltd.Inventors: Nobuaki Mitamura, Toshiharu Uesugi, Atsushi Iwasaki, Shinobu Takeyasu
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Patent number: 5855531Abstract: In a toroidal-type continuously variable transmission including input and output side disks and a pair of power roller bearings, rolling elements of the power roller bearings are made of a steel which is to be case hardened, a medium-carbon steel or a high-carbon steel which is such a steel as containing carbon in an amount of 0.2 wt % or more, and are subjected to a carbonitriding process and hardening and tempering treatments. The toroidal-type continuously variable transmission has a long life by improving the rolling life of the power roller bearings, the input side disks, and the output side disks.Type: GrantFiled: November 8, 1996Date of Patent: January 5, 1999Assignee: NSK Ltd.Inventors: Nobuaki Mitamura, Tsutomu Abe, Hideki Kokubu
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Patent number: 5853660Abstract: A bearing steel includes 0.70 to 0.93 wt % of C, 0.15 to 0.50 wt % of Si, 0.50 to 1.10 wt % of Mn and 0.3 to 0.65 wt % of Cr, with the balance being Fe and incidental impurities, and it has the ratio Cr/C specified to fall within 0.4 to 0.7. Because of these compositional features, the generation of macro carbides is prevented and the need to perform soaking at high temperature for a prolonged time is eliminated. Further, the bearing steel saves the materials cost and the overall cost of heat treatments in the manufacture of bearings and which yet is capable of satisfying the requirements of various characteristics of bearings, as well as a rolling bearing that employs the bearing steel.Type: GrantFiled: October 13, 1995Date of Patent: December 29, 1998Assignee: NSK Ltd.Inventors: Yasuo Murakami, Nobuaki Mitamura, Seiji Sato
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Patent number: 5672014Abstract: A rolling bearing has components of an inner race, an outer race and rolling elements, one of the components being formed of an alloy steel containing 0.1-1.0 wt % of C, 0.1-1.5 wt % of Si, 0.1-1.5 wt % of Mn and 0.1-3.0 wt % of Cr, the alloy steel being carbonitrided and then ground to form a surface layer having a carbon and a nitrogen concentration of 0.6-1.5 wt % and 0.05-0.9 wt %, respectively. The surface layer has an appropriate amount of retained austenite .gamma..sub.R and is sufficiently hard to insure long life even under lubrication in the presence of foreign matter. By optimizing the choice of constituent materials, processing methods and heat treatments for each of the rolling elements and the inner and outer races, rolling bearings that have high performance can be produced at low cost.Type: GrantFiled: September 29, 1995Date of Patent: September 30, 1997Assignee: NSK Ltd.Inventors: Shigeru Okita, Nobuaki Mitamura, Susumu Tanaka, Kenji Yamamura, Manabu Ohori
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Patent number: 5660647Abstract: In a rolling bearing including an inner race, an outer race and a plurality of rolling elements in which at least one member of the inner race, the outer race and the rolling elements is made of an alloy steel containing: 0.1 to 0.7 wt % of C; 0.8 to 2.0 wt % of V; 0.5 to 3.0 wt % of Cr; 0.3 to 1.2 wt % of Mn; 0.3 to 1.5 wt % of Si; at most 3.0 wt % of Mo; and the balance being Fe, the member being carburized or carbonitrided so that the member has a surface carbon concentration of 0.8 to 1.5 wt % and a surface concentration ratio V/C of 1 to 2.5 in order to cause VC-type carbides to be precipitated on a surface of the member, the rolling bearing exhibits improved wear resistance under a severe condition such as a high-temperature environment and simultaneously the rolling bearing has superior productivity.Type: GrantFiled: August 8, 1995Date of Patent: August 26, 1997Assignee: NSK Ltd.Inventors: Nobuaki Mitamura, Kenji Yamamura
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Patent number: 5626974Abstract: In a rolling bearing including an inner race, an outer race and a plurality of rolling elements in which at least one member of the inner race, the outer race and the rolling elements is made of a high carbon steel material and has a Rockwell hardness of H.sub.R C 60 or more, the high carbon steel material including, in a surface thereof, solid solution of carbon C and solid solution of nitrogen N which are adjusted to satisfy relationships of 0.8 wt %.ltoreq.C.ltoreq.1.2 wt % and 0.1 wt %.ltoreq.N.ltoreq.0.5 wt % with the balance Fe, and in which the retained austenite existing in the high carbon steel material is adjusted to substantially 0 wt %, the rolling beating exhibits superior dimensional stability and high endurance even when it is used under high-temperature conditions, and exhibits high productivity with low cost.Type: GrantFiled: August 25, 1995Date of Patent: May 6, 1997Assignee: NSK Ltd.Inventor: Nobuaki Mitamura
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Patent number: 5427457Abstract: An object of this invention is to provide a rolling bearing in which, as for the rolling elements, it is unnecessary to employ a high level heat treatment such as carburizing or carbonitriding which requires a long period of time to achieve, and which is sufficiently long in service life even when used with a lubricant containing foreign matters. In a rolling bearing, the amount of residual austenite (.gamma..sub.R vol %) in the surface layer of at least one of the inner and outer races is in a range of 25 to 40 vol %, and the surface hardness (Hv) thereof meets the following condition:-4.7.times.(.gamma..sub.R vol %)+900.ltoreq.Hv.ltoreq.-4.7.times.(.gamma..sub.R vol %)+1000and the hardness of the rolling elements combined with the inner and outer races is higher by H.sub.R C 1 to 2 than that of the one of the inner and outer races.Type: GrantFiled: October 12, 1993Date of Patent: June 27, 1995Assignee: NSK Ltd.Inventors: Kyozaburo Furumura, Yasuo Murakami, Nobuaki Mitamura, Shinichi Shirota, Shigeru Okita, Kazuo Sekino
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Patent number: 5413643Abstract: A rolling bearing is disclosed, which comprises an inner ring, an outer ring, and rolling elements each composed of an alloy steel which are, after being subjected to a carburizing treatment or a carbonitriding treatment, subjected to quench-hardening and tempering or is subjected to quench-hardening or tempering, wherein the alloy steel contains from 0.10 to 1.00% by weight C, from 0.50 to 3.00% by weight Cr, from 0.15 to 1.00% by weight Si, from 0.2 to 1.50% by weight Mn, and rest being Fe and unavoidably intermixed impurities, the average amount of the retained austenite of at least the inner ring in the inner ring and the outer ring is not more than 4% by volume and the average amount of the retained austenite of the rolling elements is from 20 to 30% by volume.Type: GrantFiled: May 13, 1994Date of Patent: May 9, 1995Assignee: NSK Ltd.Inventors: Yasuo Murakami, Kazuo Sekino, Nobuaki Mitamura
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Patent number: 5338377Abstract: In order to provide a ball-and-roller bearing that has a longer life and which exhibits higher reliability than the prior art products not only under lubrication in the presence of foreign matter but also under lubrication in clean conditions, according to the present invention, a bearing material that contains 0.2 to 1.0 wt % of carbon and at least 1 wt % in total of one or more elements selected from among chromium, molybdenum and vanadium is subjected to a carbonitriding treatment and a hardening heat treatment to make an alloy steel in which the area ratio of carbonitrides present in the surface layer of said bearing material per unit area is adjusted to be at least 10%, a maximum grain size of carbonitrides present in said surface layer being no more than 3 .mu.m, the content of retained austenite (.gamma..sub.R) in said surface layer being 25 to 45 vol %, and said surface layer having a surface hardness of at least 750 Hv.Type: GrantFiled: September 18, 1992Date of Patent: August 16, 1994Assignee: NSK Ltd.Inventors: Nobuaki Mitamura, Shigeru Okita
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Patent number: 5085733Abstract: A rolling contact parts steel has C: 0.2-0.6 wt%; Si: 0.3-2.0 wt%; Cr: 0.5-2.5 wt%; Mn: 1.7 wt% or less; O: 12 ppm or less; and the balance of Fe and an inevitable impurity. The steel produces a fine carbide without the need for a separate heat treatment. The dimensioal stability at high temperature of the steel is superior. A rolling bearing has at least one of the races and the rolling element thereof made of the steel, the steel being carburized or carbonitrided, then quenched and then, finally, tempered. The one of the races and the rolling element will not soften at a high temperature.Type: GrantFiled: August 23, 1990Date of Patent: February 4, 1992Assignee: Nippon Seiko Kabushiki KaishaInventor: Nobuaki Mitamura
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Patent number: 5084116Abstract: A rolling contact element steel has C: 0.2-0.6 wt %; Si: 0.5-2.0 wt %; Cr: 5.0-8.0 wt %; Mo: 3.0 wt % or less; Mn: 1.6 wt % or less; O: 12 ppm or less; and the balance of Fe and an inevitable impurity. A rolling bearing made of this steel will not soften even at high temperature. The dimensional stability at high temperature and wear-resistance of the steel are superior. The steel can produce a fine carbide without the need for a separate heat treatment. A rolling bearing has at least one of the races and the rolling element made of the steel, the steel being carburized or carbonitrided, then quenched and finally high-temperature tempered.Type: GrantFiled: July 31, 1990Date of Patent: January 28, 1992Assignee: Nippon Seiko Kabushiki KaishaInventor: Nobuaki Mitamura
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Patent number: 5030017Abstract: A rolling bearing has races and a rolling element. At least one of the races and the rolling element is made of a carburized or carbonitrided alloy steel. The content of a fine carbide present in the surface layer of the one element of the rolling bearing is 20-50 vol %. The content of retained austenite in the surface layer is 10-25 vol %. The rolling bearing provides a long-life rolling bearing suitable for use in a transmission and engine.Type: GrantFiled: July 24, 1990Date of Patent: July 9, 1991Assignee: Nippon Seiko Kabushiki KaishaInventors: Yasuo Murakami, Nobuaki Mitamura