Patents by Inventor J. Ernst Hartitz

J. Ernst Hartitz 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).

  • Extruded amorphous thermoplastic pipe having reduced internal stress and method of making the same
    Patent number: 5026582
    Abstract: Physical properties of extruded amorphous thermoplastic pipe are improved by a method of extrusion which allows for relaxation of internal stress introduced during the processing. The stress is relieved by using an extrusion die having an inner and outer diameter which is smaller than the final product inner and outer diameter. The extruded pipe is allowed to expand as a result of melt swell and thereby permit relaxation of internal stresses within the extruded pipe. The expansion brings the inner and outer diameter to approximately the size of the final pipe. The further introduction of internal stress is avoided by pulling the extruded pipe from the extruding apparatus at a rate which is approximately the same as the rate of extrusion. The pipe can undergo a final sizing step to bring the extruded pipe to the final product size.
    Type: Grant
    Filed: September 18, 1989
    Date of Patent: June 25, 1991
    Assignee: The B. F. Goodrich Company
    Inventor: J. Ernst Hartitz
  • Method of making extruded amorphous thermoplastic pipe having reduced internal stress
    Patent number: 4888148
    Abstract: Physical properties of extruded amorphous thermoplastic pipe are improved by a method of extrusion which allows for relaxation of internal stress introduced during the processing. The stress is relieved by using an extrusion die having an inner and outer diameter which is smaller than the final product inner and outer diameter. The extruded pipe is allowed to expand as a result of melt swell and thereby permit relaxation of internal stresses within the extruded pipe. The expansion brings the inner and outer diameter to approximately the size of the final pipe. The further introduction of internal stress is avoided by pulling the extruded pipe from the extruding apparatus at a rate which is approximately the same as the rate of extrusion. The pipe can undergo a final sizing step to bring the extruded pipe to the final product size.
    Type: Grant
    Filed: August 15, 1988
    Date of Patent: December 19, 1989
    Assignee: The B. F. Goodrich Company
    Inventor: J. Ernst Hartitz