Patents by Inventor Richard L. Riddle

Richard L. Riddle 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).

  • Metal die acid etch apparatus and process
    Patent number: 5364494
    Abstract: A metal die acid etch apparatus includes a bath for holding an acid etch solution and a hood assembly on which a metal die is supported above the bath. Structure is provided on the apparatus for exposing the metal die to the acid etch solution that is in the bath in order to etch the plate as desired. A weir is positioned at a predetermined height within the bath for draining acid solution from the top of the bath, and this drained solution is recirculated into the bath. The temperature of the acid etch solution in the bath is maintained at a predetermined temperature in order to provide a predictable and consistent etch of the metal die.
    Type: Grant
    Filed: November 29, 1993
    Date of Patent: November 15, 1994
    Assignee: Universal Engraving, Inc.
    Inventors: Glenn E. Hutchison, Richard L. Riddle