Patents by Inventor Douglas F. Shepherd

Douglas F. Shepherd 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: 5529703
    Abstract: Apparatus for inductively heating metal can lids operates at medium frequency, with a many-turn induction coil wrapped partly or entirely around the can closures. No focusing cores are required, nor need the conductors be water cooled. Can ends may be fed through the apparatus in-stick. IGBTs are used in the H-bridge of the inverter. A control system is also provided which minimizes peak current flow through the switches and obviates the need for a series inductor conventionally used for current limiting. The control system monitors the tank voltage phase angle and turns the switches on and off in optimal response thereto. Can lids are separated magnetically while being motivated by sequentially switched electromagnets, and can bodies may be rotated by a split conveyor belt while being transported through inductive heating apparatus.
    Type: Grant
    Filed: August 24, 1994
    Date of Patent: June 25, 1996
    Assignee: Nordson Corporation
    Inventors: Robert A. Sprenger, Douglas F. Shepherd