Patents by Inventor Walter A. Hedden

Walter A. Hedden 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).

  • Plaster molding composition
    Patent number: 4148660
    Abstract: A fiber-free plaster molding composition which comprises by weight approximately 50-70% gypsum plaster, 5-25% fine expanded perlite, and 5-30% of a non-fibrous filler such as mica, silica, fly ash, pyrophyllite or mixtures thereof. The composition of this invention has good dry blending properties, slurry characteristics, and wet and dry mold features, making it a suitable replacement for fiber-containing molding compositions for low fusion metal casting molds.
    Type: Grant
    Filed: December 19, 1977
    Date of Patent: April 10, 1979
    Assignee: PMCMA Research Group
    Inventors: David R. Lankard, Walter A. Hedden
  • Plaster molding composition
    Patent number: 4081283
    Abstract: A fibrous talc-free plaster molding composition comprises by weight approximately 50-70% gypsum plaster, 5-20% fibrous wollastonite, 5-25% fine expanded perlite, and 0-40% of a filler selected from the group consisting of sand, fly ash, pyrophyllite and mixtures thereof. The composition of this invention has good dry blending properties, slurry characteristics, and wet and dry mold features, making it a suitable replacement for fibrous talc-containing molding compositions for low fusion metal casting molds.
    Type: Grant
    Filed: February 23, 1976
    Date of Patent: March 28, 1978
    Assignee: PMCMA Research Group
    Inventors: David R. Lankard, Walter A. Hedden
  • Hydraulic fracturing method using sintered bauxite propping agent
    Patent number: 4068718
    Abstract: An improved method of fracturing a subterranean formation wherein particles composed of sintered bauxite are placed in the formation fracture to maintain the walls of the fracture spaced apart. The sintered bauxite particles have a specific gravity greater than 3.4 and are prepared from bauxite material having a grain size of about 12 microns or less.
    Type: Grant
    Filed: October 26, 1976
    Date of Patent: January 17, 1978
    Assignee: Exxon Production Research Company
    Inventors: Claude E. Cooke, Jr., Walter A. Hedden, William C. Chard