Granted Patent
Utility
US 4,275,994 · App. 05/893,050
Roll formed blade structure
Inventor:
William K. Underhill, Jr.
Patented Case
View Patent ↗
Granted: Jun 30, 1981
Filed: Apr 3, 1978
Inventor
William K. Underhill, Jr.
Assignee (at issue)
Textron Inc.
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.