Patents by Inventor Dennis C. Stewart

Dennis C. Stewart 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: 6098871
    Abstract: The present invention relates to a process for joining two metal members together. The process comprises the steps of providing two parent metal members to be joined and a prealloyed interlayer foil having a melting point depressant; creating a joint interface by positioning the foil between two spaced apart surfaces of the two parent metal members to be joined together; applying a load substantially transverse to the joint interface which does not cause deformation of the surfaces; and applying localized rapid heating in the area of the joint interface at a temperature sufficient to effect bonding of the two metallic members while causing little or no degradation of microstructural or mechanical properties of the parent metal and a coarsening of grain size in rim portions of the metal members.
    Type: Grant
    Filed: July 22, 1997
    Date of Patent: August 8, 2000
    Assignee: United Technologies Corporation
    Inventors: Ronald R. Cairo, John M. Robertson, J. Carter Barone, Dennis C. Stewart
  • Patent number: 5111990
    Abstract: A method is disclosed for controlling the magnitude and location of the weld notch which results from inertia welding of certain materials, such as superalloys. By controlling the size and geometry of the articles being joined a curved weld zone will result and the material expelled from the weld zone which produces the weld notch will be directed in a fashion which moves the weld notch outside of the original diameter of the articles being joined. The resultant welded article consisting of a larger portion and a smaller portion can be machined to the size of the smaller portion without any residual weld notch.
    Type: Grant
    Filed: December 20, 1988
    Date of Patent: May 12, 1992
    Assignee: United Technologies Corporation
    Inventors: Jack S. Thrower, Dennis C. Stewart, Enrique E. Montero
  • Patent number: 4705203
    Abstract: Methods of repairing defects in superalloy articles are described. Defective areas are cleaned and prepared to expose clean substrate surfaces. A layer of superalloy powder material containing a melt depressant (boron) is applied. A layer of superalloy material essentially free from boron is then applied. The dual coated article is heated to a temperature at which the boron containing layer melts, but the boron-free layer does not. The boron diffuses into the substrate raising the melting point of the molten material until solidification results. The unmelted surface layer is subsequently removed leaving behind a repaired article free from surface defects.
    Type: Grant
    Filed: August 4, 1986
    Date of Patent: November 10, 1987
    Assignee: United Technologies Corporation
    Inventors: Charles C. McComas, Dennis C. Stewart
  • Patent number: 4077247
    Abstract: A method of improving the formability of sheet metal wherein the sheet metal is formed by die pins contacting spaced parts of the sheet with the properties of the sheet material itself determining the actual condition of curvature between the spaced parts contacted by the die pins. The sheet metal is perforated at the spaced part of the sheet contacting each die pin so that as each die pin is pressed into the sheet, each perforation expands and additional sheet material is supplied to the shoulder of the pin. Tops of the die pins can be modified with a boss to locate the perforations in the sheet metal and position it in respect to the die pins. Modified die pin tops can be formed with pointed inserts so that solid sheet metal can be used with the inserts piercing the sheet and the die pins then forming it. The sheet metal can also be partially formed and then perforated before the final forming.
    Type: Grant
    Filed: September 30, 1975
    Date of Patent: March 7, 1978
    Assignee: United Technologies Corporation
    Inventor: Dennis C. Stewart