Granted Patent
Utility
US 4,336,077 · App. 06/189,957
Method of cryogenically hardening an insert in an article
Inventors:
J. Michael Leach, Walter L. Harvey
Patented Case
View Patent ↗
Granted: Jun 22, 1982
Filed: Mar 3, 1980
Inventors
J. Michael Leach
Walter L. Harvey
Assignee (at issue)
Caterpillar Tractor 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.