Patents by Inventor Charles D. Spragg

Charles D. Spragg 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).

  • Patent number: 5156781
    Abstract: A compact and precision extrusion system and method for extruding strips of rubber compounds with profiles of accurate dimensions. Strips of rubber compound are uniformly heated and mixed in an extruder and then passed through a low pressure drop strainer to remove foreign matter. The strained compound then is fed directly into a gear pump which delivers precise volumes of the rubber compound immediately into the spread chamber of an extrusion head after which it passes through a die to form a precise strip of the rubber compound. The strainer and extrusion head are movably mounted with respect to the gear pump for axial separation from the gear pump for easy removal of the rubber compound from the various components of the system to facilitate compound changes. A control system regulates the speed of the extruder to provide a near constant pressure at the entrance port of the gear pump to precisely regulate the rate of extrusion of the compound from the extrusion head.
    Type: Grant
    Filed: December 24, 1990
    Date of Patent: October 20, 1992
    Assignee: Bridgestone Corporation
    Inventors: Georg G. A. Bohm, Arthur W. Greenstreet, Gregory D. Chaplin, Charles D. Spragg
  • Patent number: 4918017
    Abstract: A screen assembly for mounting on the outlet end of an extruder for removing foreign particles from an elastomeric material being discharged from the extruder. The assembly includes a screen support member having a plurality of spaced elongated ribs formed integrally with or removably mounted on a surrounding member. The spaced ribs form a plurality of elongated slots therebetween which provide flow paths for the elastomeric material, and preferably are concavely-shaped in the direction of travel of the extruded material. A mesh screen formed of a high tensile strength, work hardened stainless steel wire cloth is formed complementary to the concavity of the ribs and is mounted in juxtaposition to the ribs for removing the foreign particles as the elastomeric material passes through the screen.
    Type: Grant
    Filed: February 3, 1989
    Date of Patent: April 17, 1990
    Assignee: Bridgestone/Firestone, Inc.
    Inventors: Arthur W. Greenstreet, Gerardo P. Elia, Charles D. Spragg