Patents by Inventor Massaki Tahara

Massaki Tahara 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).

  • Patent number: 5340412
    Abstract: An austenitic stainless steel screw having a nitride hard layer on its surface to prevent corrosion on parts of the screw such as a screw head which is in contact with the environment by removing a portion of the nitride hard layer to expose austenitic stainless steel base. By contrast, in the thread part and the like of the screw, the nitride hard layer is retained to improve the hardness and the tapping functions of the screw. In the method for manufacturing, the austenitic stainless steel screw is exposed to a fluorine-or fluoride-containing gas atmosphere prior to nitriding to form a fluoride film on its surface and then is nitrided in that state. Accordingly, the so formed nitride hard layer becomes uniform and deep to obtain an austenitic stainless steel screw having excellent surface properties.
    Type: Grant
    Filed: May 6, 1993
    Date of Patent: August 23, 1994
    Assignee: Daidousanso Co., Ltd.
    Inventors: Akira Yoshino, Massaki Tahara, Haruo Senbokuya, Kenzo Kitano, Teruo Minato