Patents by Inventor David L. Mitchell

David L. Mitchell 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: 5613185
    Abstract: The present invention discloses novel nitrogen-hydrogen based atmospheres for sintering steel components in continuous furnaces with consistent quality and properties while prolonging the life of the wire mesh belts, reducing maintenance costs, and improving furnace productivity. Specifically, it discloses the use of a controlled amount of an oxidizing agent such as moisture, carbon dioxide, nitrous oxide, or mixtures thereof along with nitrogen-hydrogen atmospheres. The amount of an oxidizing agent added to the nitrogen-hydrogen atmospheres to pre-condition belt material prior to its use for sintering and to sinter steel components is controlled in such a way that atmospheres become oxidizing to the belt material but reducing to steel components being sintered, specifically in the high heating and cooling zones of continuous furnaces.
    Type: Grant
    Filed: June 1, 1995
    Date of Patent: March 18, 1997
    Assignee: Air Products and Chemicals, Inc.
    Inventors: James G. Marsden, Donald J. Bowe, Kerry R. Berger, Diwakar Garg, David L. Mitchell, Jr.
  • Patent number: 5584334
    Abstract: A method in particular, comprises the steps of: (a) preparing a mold having a sprue leading to a substantially horizontally oriented runner, at least one riser extending from the runner, and walls defining a mold cavity in communication with the riser; (b) providing a shallow reaction chamber in the runner containing grain refining inoculant solids therein, the inoculant having a surface exposed substantially tangentially to the flow of molten metal through the runner; (c) pouring a charge of molten aluminum into the sprue with a sufficient pressure head to fill the cavity, the flow being substantially laminar through the runner; and (d) inverting the mold substantially immediately after mold filling and prior to solidification of the metal in the mold cavity.
    Type: Grant
    Filed: December 6, 1994
    Date of Patent: December 17, 1996
    Assignee: Ford Motor Company
    Inventors: James L. Oswald, Paul M. LeTarte, Paul A. Ballas, David L. Mitchell
  • Patent number: 5352523
    Abstract: Graphite carbon surfaces are protected from elevated temperature oxidation and mechanical wear by electric arc thermal spray coating exposed surfaces with a titanium nitride or multi-element (e.g., aluminum-silicon-titanium) coating.
    Type: Grant
    Filed: May 8, 1992
    Date of Patent: October 4, 1994
    Assignee: Air Products and Chemicals, Inc.
    Inventors: Zbigniew Zurecki, Edward A. Hayduk, Jr., John G. North, Robert B. Swan, David L. Mitchell, Jr.
  • Patent number: 5348592
    Abstract: An improved method for producing substantially moisture- and oxygen-free, nitrogen-hydrogen atmospheres suitable for annealing, hardening, brazing, and sintering ferrous and non-ferrous metals and alloys is disclosed. According to the disclosed method, suitable nitrogen-hydrogen atmosphere is produced by 1) generating a nitrogen stream containing about 0.1 to 5% residual oxygen by a known non-cryogenic air separation technique, 2) mixing it with a pre-determined but more than stoichiometric amount of hydrogen required to convert residual oxygen to moisture, 3) converting residual oxygen to moisture by reaction with hydrogen in a catalytic reactor, 4) cooling the reactor effluent stream, and 5) removing moisture from it in a regenerative sorbent dryer.
    Type: Grant
    Filed: February 1, 1993
    Date of Patent: September 20, 1994
    Assignee: Air Products and Chemicals, Inc.
    Inventors: Diwakar Garg, Brian B. Bonner, Paul T. Kilhefner, Paul A. Mattiola, David L. Mitchell
  • Patent number: 5304417
    Abstract: Graphite carbon surfaces are protected from elevated temperature oxidation and mechanical wear by electric arc thermal spray coating exposed surfaces with a titanium nitride or multi-element (e.g., aluminum-silicon-titanium) coating.
    Type: Grant
    Filed: June 2, 1989
    Date of Patent: April 19, 1994
    Assignee: Air Products and Chemicals, Inc.
    Inventors: Zbigniew Zurecki, Edward A. Hayduk, Jr., John G. North, Robert B. Swan, David L. Mitchell, Jr.
  • Patent number: 5254359
    Abstract: Graphite and/or carbon surfaces are coated with a titanium nitride coating by exposing the substrate to electric arc thermal spray process wherein titanium wire as the source of titanium and nitrogen is used as the propelling (atomizing) gas.
    Type: Grant
    Filed: June 14, 1991
    Date of Patent: October 19, 1993
    Assignee: Air Products and Chemicals, Inc.
    Inventors: Zbigniew Zurecki, Edward A. Hayduk, Jr., John G. North, Robert B. Swan, David L. Mitchell, Jr.
  • Patent number: 5220802
    Abstract: Method and apparatus for quick freezing particles with surface moisture by immersion in liquid cryogen to produce a frozen crust or layer on the particles followed by agitation in content with the vaporized cryogen to complete freezing and prevent clumping of the particles.
    Type: Grant
    Filed: July 21, 1992
    Date of Patent: June 22, 1993
    Assignee: Air Products and Chemicals, Inc.
    Inventors: Edward F. Kiczek, Earl W. Moore, David L. Mitchell, Jr., Kevin S. McAfee
  • Patent number: 5168723
    Abstract: Method and apparatus for quick freezing particles with surface moisture by immersion in liquid cryogen to produce a frozen crust or layer on the particles followed by agitation in content with the vaporized cryogen to complete freezing and prevent clumping of the particles.
    Type: Grant
    Filed: November 7, 1991
    Date of Patent: December 8, 1992
    Assignee: Air Products and Chemicals, Inc.
    Inventors: Edward F. Kiczek, Earl W. Moore, David L. Mitchell, Jr., Kevin S. McAfee
  • Patent number: 5115710
    Abstract: A submarine launched missile generates undesirable stress on the rocket nle hydraulic control system at the moment of ignition of the rocket motor. This stress can be minimized by operating the system so that the nozzle is near center and the hydraulic actuator valves are open at ignition.
    Type: Grant
    Filed: February 19, 1991
    Date of Patent: May 26, 1992
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: David L. Mitchell, Alan J. Stein, Charles L. Barndt, Jr., William W. Szeto
  • Patent number: 4972314
    Abstract: A single instruction stream multiple data steam data flow signal processor and method for implementing macro data flow control, in which a plurality of data processors have contentionless access to global memory data. Data processing tasks for the data processors, such as primitive executions together with graph scheduling processes, are developed asynchronously and in parallel from a command program and a macro data flow control graph.
    Type: Grant
    Filed: July 5, 1988
    Date of Patent: November 20, 1990
    Assignee: Hughes Aircraft Company
    Inventors: Thomas W. Getzinger, Hans L. Habereder, R. Loyd Harrison, Donald M. Hopp, David L. Mitchell, Chao-Kuang Pian, John A. Propster
  • Patent number: 3938590
    Abstract: Disclosed is a process for recovering petroleum from subterranean, viscous asphaltic or bituminous petroleum-containing formations, including subterranean tar sand deposits. A zone of gas permeability is established in the formation first, such as by fracturing or gas sweeping a section of the formation. Oxidizing gas such as oxygen, air, oxygen enriched air, ozone, or chlorine, or a mixture of steam and an oxidizing gas is introduced into the zone of increased gas permeability to expand the zone and further to cause a reaction to occur between the oxidizing gas and the oxygen-susceptible groups or labile groups associated witn the bituminous or asphaltic petroleum molecules forming acidic or aldehyde groups. Next, a gaseous or liquid alkalinity agent such as ammonia is introduced into the formation to react with the oxidatively pre-treated groups in the bituminous or asphaltic petroleum to form surface active agents or surfactants in situ.
    Type: Grant
    Filed: June 26, 1974
    Date of Patent: February 17, 1976
    Assignee: Texaco Exploration Canada Ltd.
    Inventors: David A. Redford, David L. Mitchell
  • Patent number: D351632
    Type: Grant
    Filed: April 2, 1993
    Date of Patent: October 18, 1994
    Inventor: David L. Mitchell