Patents by Inventor Tomoyuki Hirakawa

Tomoyuki Hirakawa 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).

  • Plug for manufacturing seamless steel pipe
    Patent number: 5031434
    Abstract: A plug for manufacturing a seamless steel pipe is disclosed. The plug includes the surface layer made of molybdenum or molybdenum base alloy coming in contact with a workpiece to be drilled and the core covered with the surface layer. The surface of the core being in contact with the surface layer is formed uneven. According to the invention, the surface layer and the core are strongly joined together, and the life of the plug is elongated.
    Type: Grant
    Filed: February 28, 1990
    Date of Patent: July 16, 1991
    Assignee: NKK Corporation
    Inventors: Akira Takase, Takashi Tamura, Tsuneo Oikawa, Yutaka Mihara, Tomoyuki Hirakawa, Takeshi Kuwano
  • Water-dispersion lubricant of graphite, particulate resin and high molecular weight polybasic acid salt
    Patent number: 5030367
    Abstract: Disclosed herein is a water-dispersion-type hot-rolling lubricant for the production of seamless steel pipes. This lubricant features the inclusion of a salt of a polybasic high molecular acid in addition to fine graphite powder, a water-insoluble fine particulate synthetic resin and water as principal components and fine gilsonite powder as an optional component. Even when the surface temperature of a mandrel bar is in a high temperature range of 100.degree.-400.degree. C., this lubricant can form a uniform and thick coating film on the surface of the bar so that the lubricant can exhibit extremely good hot-rolling lubrication performance.
    Type: Grant
    Filed: August 30, 1989
    Date of Patent: July 9, 1991
    Assignees: Nippon Kokan Kabushiki Kaisha, Yushiro Chemical Industry Co., Ltd.
    Inventors: Megumu Tanaka, Koji Sakura, Tatsuharu Oda, Tomoyuki Hirakawa, Yasuhiro Sotani, Fuyuhiko Kajiyama, Noboru Kanda, Hiroo Hosono, Toshitaka Wakabayashi, Hitoshi Hasegawa