Granted Patent
Utility
US 4,540,539 · App. 06/451,666
Method and apparatus for production of concrete pipe by the packerhead method
Inventors:
Gerald R. Crawford, Brian J. Kozlowski
Patented Case
View Patent ↗
Granted: Sep 10, 1985
Filed: Dec 21, 1982
Inventors
Gerald R. Crawford
Brian J. Kozlowski
Assignee (at issue)
International Pipe Machinery 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.