ALEXANDRIA, Va., June 9 -- United States Patent no. 12,285,809, issued on April 29, was assigned to NACHI-FUJIKOSHI CORP. (Tokyo).
"Hard-film-coated drill" was invented by Junichi Noshiro (Toyama, Japan) and Ryo Hayashi (Toyama, Japan).
According to the abstract* released by the U.S. Patent & Trademark Office: "In a hard-film-coated drill having a cemented carbide drill body coated with a hard film, the drill body is provided with a smooth region at a boundary between a flank surface and a rake surface. The surface hardness of the hard film is within 2000 to 2500 HV in Vickers hardness. A radius r1 (micro metre) of curvature of the first ridgeline L1 where the smooth region and the flank surface intersect is represented by r1=0.45xD+a1 (1...