Granted Patent
Utility
US 5,720,993 · App. 08/746,078
Collapsible core for concrete pipe making apparatus
Inventor:
Jon A. Schmidgall
Patented Case
View Patent ↗
Granted: Feb 24, 1998
Filed: Nov 6, 1996
Inventor
Jon A. Schmidgall
Assignee (at issue)
Hawkeye Concrete Products Co.
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.