Lowe, Price, LeBlanc & Becker
Fastening screw
 A fastening screw is provided with a locking function to prevent loosening thereof after being tightened. In one aspect of the invention, the fastening screw has a head having a bearing face; a plurality of convex portions and concave portions formed on the bearing face to provide shallow wavelike portions proceeding in a circumferential direction of the bearing face; and a thread portion having a flat top portion, the width of the flat portion being larger than that of a root of a thread portion of an internal thread, wherein the angle between a slant surface of the fastening screw on a screw-tightening side and a line vertical to an axis of the fastening screw is substantially equal to the angle between a slant surface of the internal thread on a screw-loosening side and the line vertical to the axis of the fastening screw, and the angle between a slant surface of the fastening screw on the screw-loosening side and the vertical line is smaller than the angle between the slant surface of the fastening screw on the screw-tightening side and the vertical line. 
Kabushiki Kaisha Suzuki Rashi Seisakusho
F F
F16B F16B
inventional inventional
Yasuo
Suzuki