Patents by Inventor Andrew Stephenson Dalgleish Crum

Andrew Stephenson Dalgleish Crum 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).

  • Multizone electrical furnace methods and apparatus
    Patent number: 4011430
    Abstract: In a multizone electrical furnace the phase shift effect of the thyristor devices used to control the power supplied to each thermal zone is reduced by providing two or more heater circuits, each including a thyristor device and a heating element, for each thermal zone. The thyristor devices are controlled so that only one thyristor device associated with each thermal zone is operating to produce a substantial phase shift at any time. Over-powering the heating elements at higher furnace temperatures may also be prevented by connected two or more heating elements associated with a thermal zone to one of the thyristor devices associated with that zone above a predetermined threshold temperature.
    Type: Grant
    Filed: May 6, 1975
    Date of Patent: March 8, 1977
    Assignee: National Forge Company
    Inventors: Donald Eli Witkin, Andrew Stephenson Dalgleish Crum
  • Hot isostatic press
    Patent number: 3973886
    Abstract: A hot isostatic press which includes a mantle interposed between heating elements and the wall of the press and means associated with the press for equalizing the pressure on both sides of said mantle during operation of the press or during pressurization or depressurization.
    Type: Grant
    Filed: May 6, 1975
    Date of Patent: August 10, 1976
    Assignee: National Forge Company
    Inventor: Andrew Stephenson Dalgleish Crum