Granted Patent
Utility
US 4,496,387 · App. 06/547,169
Transition between batch preheating and liquefying stages apparatus
Inventors:
Robert B. Heithoff, John K. Groetzinger, Ronald L. Schwenninger
Patented Case
View Patent ↗
Granted: Jan 29, 1985
Filed: Oct 31, 1983
Inventors
Robert B. Heithoff
John K. Groetzinger
Ronald L. Schwenninger
Assignee (at issue)
PPG Industries, 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.