Granted Patent
Utility
US 4,256,449 · App. 06/062,172
Draw-forming of stretchable thermoplastic material into hollow articles
Inventor:
Donald G. Sauer
Patented Case
View Patent ↗
Granted: Mar 17, 1981
Filed: Jul 30, 1979
Inventor
Donald G. Sauer
Assignee (at issue)
National Crane Corporation
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.