Granted Patent
Utility
US 5,320,331 · App. 07/833,590
Method and apparatus for forming corrugations in tubing and a corrugated tube produced thereby
Inventor:
Robert R. Hellman, Sr.
Patented Case
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Granted: Jun 14, 1994
Filed: Feb 10, 1992
Inventor
Robert R. Hellman, Sr.
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.