Granted Patent
Utility
US 4,832,889 · App. 07/140,444
Vaulted screw/grooved barrel extrusion machine, method and system
Inventor:
D. Emil Johnson
Patented Case
View Patent ↗
Granted: May 23, 1989
Filed: Jan 4, 1988
Inventor
D. Emil Johnson
Assignee (at issue)
Mobil Oil 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.