Patents by Inventor Toshiyuki Sunakoda

Toshiyuki Sunakoda 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: 5123217
    Abstract: A drill for use in drilling hard and brittle materials includes a shank and a drilling portion attached to one end of the shank. The drilling portion includes a tapered primary cutting edge, a first secondary cutting surface extending from the primary cutting edge and having an angle of taper substantially identical to that of the primary cutting edge, and a second secondary cutting surface extending from the first secondary cutting surface and containing a line substantially parallel to the central axis of the drill. The primary cutting edge has a first abrasive grain layer, and the first and second secondary cutting surfaces both have a second abrasive grain layer. The first and second abrasive grain layers both have a binder made of material selected from the group consisting of metal, resin and glass. Each abrasive grain in the first abrasive grain layer has a diameter greater than that of each abrasive grain in the second abrasive grain layer.
    Type: Grant
    Filed: August 29, 1990
    Date of Patent: June 23, 1992
    Assignee: Kabushiki Kaisha Fujikoshi
    Inventors: Tadao Ishikawa, Yutaka Yoshida, Toshiyuki Sunakoda