Granted Patent
Utility
US 4,928,777 · App. 07/120,718
Cutting elements for rotary drill bits
Inventor:
David N. Shirley-Fisher
Patented Case
View Patent ↗
Granted: May 29, 1990
Filed: Nov 5, 1987
Inventor
David N. Shirley-Fisher
Assignee (at issue)
NL Petroleum Products Limited
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.