Patents Assigned to Miyagawa Kinzoku Kogyo Company Limited
  • Screw and screw forming tool
    Patent number: 4384812
    Abstract: A screw having a star-shaped socket hole in the top surface of the screw head in the form of two equilateral octagons which are disposed between a regular octagon and a regular square inscribed in the regular octagon and which are placed one upon another in concentric and out-of-phase relation with a phase shift of about 45.degree. so that there are eight convex regions which alternate with eight concave regions. A tool for forming the same is also disclosed.
    Type: Grant
    Filed: March 31, 1980
    Date of Patent: May 24, 1983
    Assignee: Miyagawa Kinzoku Kogyo Company Limited
    Inventor: Einosuke Miyagawa