Patents by Inventor David MacKenzie Hill

David MacKenzie Hill 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).

  • Process of making a yarn
    Patent number: 6303063
    Abstract: A method of converting a plastics material into a yarn includes heating the material to melt it and pumping the melted material through an extrusion die (114) to form an extruded filament (116). The extruded filament is cooled and passed through a first draw roller assembly (122) while elevating the temperature of the filament. The filament (116) is heated in a heating zone (126) as it exits the first draw roller assembly. Thereafter the filament is passed through a second draw roller assembly (134) operating at a different linear speed to the first draw roller assembly (122). The filament (116) is spooled after exiting the second draw roller assembly (134).
    Type: Grant
    Filed: June 11, 1999
    Date of Patent: October 16, 2001
    Assignee: Peri-Dent Limited
    Inventors: Ian Roberts, David MacKenzie Hill