Patents by Inventor Richard R. Knittel

Richard R. Knittel has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Multilayer tubular extrusion die
    Patent number: 4182603
    Abstract: A coextrusion die for extruding multilayer thermoplastic material in the form of a tube. The die is of the type known as a spiral mandrel die wherein the die mandrels are provided with helical grooves on their peripheries. At least one spiral mandrel has helical grooves of opposite hand than those of the remaining mandrels.
    Type: Grant
    Filed: March 27, 1978
    Date of Patent: January 8, 1980
    Assignee: Egan Machinery Company
    Inventor: Richard R. Knittel