Method of molding foam/aluminum flake microwave lenses
AssigneeGeneral Dynamics, Pomona Division
InventorCraig R. Auletti
Life of this patent
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Abstract
A microwave lens is constructed of a homogeneous body of closed cell rigid polyurethane foam with aluminum flakes dispursed throughout and having a configuration defining an axis and opposed lens surfaces. The method of the invention includes selecting a mold having a cavity of the appropriate configuration, preheating the mold, and filling the mold with a mixture of low density polyurethane foam components and fine aluminum flakes evenly dispersed throughout the foam structure allowing the mixture to cool and form a body of the appropriate configuration.
Claims15
A method of making a microwave lens comprising the steps of:
- selecting a mold having a cavity of the desired configuration for the controlled directing of microwaves;
- polishing the walls of said cavity;
- preheating said mold to a predetermined temperature;
- selecting and preparing a mixture consisting of low density polyurethane foam components and fine aluminum flakes;
- filling said mold cavity with said mixture;
- selecting a venting cover having a predetermined venting characteristic;
- installing the cover on the mold cavity;
- allowing the mold to cool and simultaneously allowing the contents to expand and cool;
- opening said mold by removing said venting cover;
- and
- removing the formed lens from the mold.
A method of making a microwave lens having at least one curved surface for the controlled directing of microwaves apprising the steps of:
- selecting a mold having a cavity of a predetermined configuration for shaping a lens for controlled passage of microwaves;
- polishing the walls of said cavity to a finish of about six micron;
- preheating said mold to a predetermined temperature of about 105.degree. Fahrenheit for a period of about 20 minutes;
- selecting and preparing a mixture of a low density polyurethane foam components for producing an expandable closed cell rigid polyurethane foam and a quantity of metal flakes for establishing a lens of a predetermined dielectric;
- placing a selected quantity of said mixture in said mold cavity;
- selecting a venting mold cover having inner and outer concentric circles of vent holes arranged along a radius at an angle of about 45.degree. to one another around the center axis of said mold to provide uniform venting of the entire mold for uniformly expanding the material in a manner to provide a lens body;
- installing the cover on the mold cavities;
- simultaneously allowing the contents of said mold cavity to expand and cool while allowing the mold to cool;
- and
- opening said mold and removing the resulting lens from the mold.
Dependencies are inferred from the claim text.