Granted Patent
Utility
US 4,565,471 · App. 06/428,717
Drill bit
Inventors:
Hideo Negishi, Kaoru Goto, Sueji Takaya
Patented Case
View Patent ↗
Granted: Jan 21, 1986
Filed: Sep 30, 1982
Inventors
Hideo Negishi
Kaoru Goto
Sueji Takaya
Assignee (at issue)
Mitsubishi Kinzoku Kabushiki Kaisha
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.