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    METHOD FOR MANUFACTURING A BEARING WASHER
    1.
    发明申请
    METHOD FOR MANUFACTURING A BEARING WASHER 审中-公开

    公开(公告)号：US20200318686A1

    公开(公告)日：2020-10-08

    申请号：US16303592

    申请日：2017-04-24

    Applicant: NTN CORPORATION

    Inventor： Kohei MIZUTA ,  Chikara OHKI ,  Hiroki FUJIWARA

    IPC: F16C33/64 ,  B21D28/02 ,  B21D37/16 ,  B21D53/10 ,  B21D53/20 ,  B21J1/06 ,  B21J5/08 ,  C21D1/18 ,  C21D9/40 ,  F16C33/62

    Abstract: A steel material is heated and punched while tension is applied to the steel material (2) in at least one direction along a surface of the steel material between first and second portions of the steel material distant from each other with forming unit posed therebetween. The tension is applied to increase a distance between the first and second portions of the steel material by a length corresponding to an amount by which the distance between the first and second portions of the steel material thermally expands as the steel material is heated to the temperature in the step of heating and punching. The forming unit includes a first die for punching the steel material and a second die facing the first die, the first die or the second die having a forming surface having a concave curved surface.

    BEARING PART AND ROLLING BEARING
    4.
    发明公开
    BEARING PART AND ROLLING BEARING 审中-公开

    公开(公告)号：US20240035515A1

    公开(公告)日：2024-02-01

    申请号：US18025379

    申请日：2021-09-16

    Applicant: NTN Corporation

    Inventor： Naoki FUJIMURA ,  Masahiro YAMADA ,  Chikara OHKI

    IPC: F16C33/62 ,  F16C19/06 ,  C21D9/40 ,  C21D1/18 ,  C21D1/74 ,  C23C8/32

    CPC classification number: F16C33/62 ,  F16C19/06 ,  C21D9/40 ,  C21D1/18 ,  C21D1/74 ,  C23C8/32 ,  C21D2211/003 ,  C21D2211/008

    Abstract: A bearing part (10) is composed of a steel, and has a quench-hardened layer (11) in a surface of the bearing part. The quench-hardened layer includes a plurality of martensite crystal grains. The plurality of martensite crystal grains are classified into a first group and a second group. A minimum value of crystal grain sizes of the martensite crystal grains belonging to the first group is larger than a maximum value of crystal grain sizes of the martensite crystal grains belonging to the second group. A value obtained by dividing a total area of the martensite crystal grains belonging to the first group by the total area of the plurality of martensite crystal grains is more than or equal to 0.3. A value obtained by dividing, by the total area of the plurality of martensite crystal grains, a total area of the martensite crystal grains belonging to the first group except for a martensite crystal grain that has a minimum crystal grain size and that belongs to the first group is less than 0.3. An average grain size of the martensite crystal grains belonging to the first group is less than or equal to 1.5 μm. The quench-hardened layer (11) further includes a plurality of cementite grains. A number density of cementite grains each having a grain size of more than or equal to 1 μm is more than or equal to 0.025/μm2.

    ROLLING COMPONENT AND ROLLING BEARING
    9.
    发明申请
    ROLLING COMPONENT AND ROLLING BEARING 有权

    公开(公告)号：US20240418213A1

    公开(公告)日：2024-12-19

    申请号：US18698145

    申请日：2022-09-28

    Applicant: NTN CORPORATION

    Inventor： Masahiro YAMADA ,  Miyu SATO ,  Noriaki MIWA ,  Kohei MIZUTA ,  Chikara OHKI

    IPC: F16C33/32 ,  C21D1/18 ,  C21D9/00 ,  C22C38/04 ,  C22C38/22 ,  C22C38/24 ,  C23C8/26

    Abstract: A rolling component has a surface and is made of steel. The rolling component comprises a surface layer portion that is a region up to 20 μm in depth from the surface. The steel contains 0.70 mass percent or more and 1.10 mass percent or less of carbon, 0.15 mass percent or more and 0.35 mass percent or less of silicon, 0.30 mass percent or more and 0.60 mass percent or less of manganese, 1.30 mass percent or more and 1.60 mass percent or less of chromium, 0.01 mass percent or more and 0.50 mass percent or less of molybdenum, and 0.01 mass percent or more and 0.50 mass percent or less of vanadium, with a balance consisting of iron and unavoidable impurities. In the surface layer portion, the steel has a nitrogen concentration of 0.2 mass percent or more.

    BEARING PART AND ROLLING BEARING
    10.
    发明申请
    BEARING PART AND ROLLING BEARING 审中-公开

    公开(公告)号：US20200378442A1

    公开(公告)日：2020-12-03

    申请号：US16954997

    申请日：2018-12-05

    Applicant: NTN CORPORATION

    Inventor： Masahiro Yamada ,  Chikara OHKI

    IPC: F16C33/62 ,  C22C38/44 ,  C22C38/04 ,  C22C38/00 ,  C22C38/02 ,  C21D9/40 ,  C21D9/36 ,  C21D1/06 ,  C23C8/32 ,  C23C8/80

    Abstract: A bearing part according to one embodiment of the present invention is a bearing part composed of a chromium molybdenum steel, the bearing part including a diffusion layer in a surface of the bearing part. The diffusion layer includes a plurality of compound grains and a plurality of martensite blocks. An average grain size of the compound grains is less than or equal to 0.3 μm. An area ratio of the compound grains in the diffusion layer is more than or equal to 3%. A maximum grain size of the plurality of martensite blocks is less than or equal to 3.8 μm.

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