Northrop Grumman Systems Corporation

Northrop Corporation

John E Potter

William T Mead

Stephen P Grossman

Keith Alan Olsen

Martin J McLaughlin

Robert L Harshberger, Jr

Tom Hurka

Norma J Cretal

Narciso Gonzales

John A Van Hamersveld

Methods of forming shaped adhesive fillets are disclosed. The adhesive fillets may be made by stacking multiple layers of adhesive sheets, consolidating the stacked layers, cutting strips from the consolidated layers, and forming the strips into adhesive fillets having desired cross sectional shapes. The fillets may be formed by feeding the strips through an apparatus comprising opposing rollers and a catcher, which facilitates release of the adhesive fillets from the rollers. The formed adhesive fillets are useful for applications such as stiffened panels for aircraft.

Adhesive fillets and method and apparatus for making same

Adhesive fillets and method for making same

The invention is an apparatus for de-bulking a composite material preform laid up in a mold. In detail, the apparatus includes a flexible cover adapted to fit over the mold and preform and attach to the sides of the mold. The cover includes an inlet port located in the cover such that when the cover is fit over the mold and preform, the inlet port positioned over the preform. A stretchable cord seals the peripheral portions of the cover to the sides of the mold forming a chamber over the preform. A hot air pump is coupled to the inlet port of the cover for pumping hot air into the chamber.

Heating apparatus for in-situ de-bulking composite parts during layup

There is provided a variable pressure roller system for installing a preform having contact surfaces onto a configuration of a mold surface by applying pressure thereon. The roller system of the present invention comprises a roller carriage. A grasping handle may be mounted to the roller carriage. Moreover, the roller system may further comprise a plurality of rollers, wherein each respective one of the plurality of rollers is defined by a weight to generate a specific pressure corresponding thereto. Furthermore, each respective one of the plurality of rollers may be removably engageable to the roller carriage. Each respective one of the plurality of rollers may be adapted to uniformly distribute the specific pressure corresponding thereto on the contact surfaces for conforming the preform to the configuration of the mold surface when engaged to the roller carriage.

Conformal transverse hat profile roller

A reusable vacuum bag is configured for application of at least one sealant bead for providing vacuum tight sealing of the reusable vacuum bag to a forming tool during fabrication of a composite part. The reusable vacuum bag comprises at least one elastomeric layer and a fluoroelastomeric strip. The elastomeric layer is sealable to the forming tool and has a sealing flange extending peripherally thereabout. The fluoroelastomeric strip extends substantially along the sealing flange and has first and second surfaces. The elastomeric layer and the fluoroelastomeric strip each have polymers and a peroxide curative. The peroxide curative initiates vulcanization wherein the polymers of each material cross-link at an elevated temperature to form double-oxygen bonds such that a permanent bond is formed between the sealing flange and the fluoroelastomeric strip at the first surface. The fluoroelastomeric strip is releaseably adhered at the second surface to the sealant bead.

Seal-less reusable vacuum bag

Method and apparatus for making a fiber reinforced composite wherein fiber reinforcement material is disposed in a molding cavity formed between a substantially rigid molding tool and a compliant molding tool in a pressurizable chamber of a pressure vessel, such as an autoclave. Uncured polymer resin is introduced under pressure to the molding cavity by a resin pump disposed in the chamber or external thereof so as to initially infiltrate the fiber reinforcement material with the resin. The chamber is gas pressurized to provide isostatic pressure on the rigid and compliant tools during resin infiltration of the fiber reinforcement material. The resin-infiltrated fiber reinforcement material then is heated in the chamber to cure the resin matrix. Large surface area composites of the aerospace skin structure type can be made using the present invention.

Isostatic pressure resin transfer molding

Ultra strong lightweight core material capable of sustained operation at unusually high temperatures for composite structure of the type used in aircraft parts such as wings, fairings and stabilizers is produced from preimpregnated thermoplastic fibercloth ribbon by the manufacturing processes of this invention. The fibercloth ribbon is preformed between corrugated rollers of a special roll forming press which heats the ribbon to a softening temperature, forms it into a pattern of half-hex corrugations, cools it and sets it in that pattern. Then sheets cut from the corrugated ribbon are stacked into a bonding press along with hex forming mandrels placed between the sheets in the corrugations. With a full stack, the press is enclosed with side covers containing heating units, hydraulic pressure is applied to compress and consolidate the stack and contact interfacial facets, and heat is applied by directing superheated air jets on the mandrel ends until a bonding temperature is reached, forming the material accurately around the hex mandrels and fusion bonding adjacent sheets together at interfacial facets in a honeycomb pattern. After cooling to a setting temperature, pressure is removed and the bonded stack is removed from the bonding press. The mandrels are then extracted in a special long stroke thin pin pneumatic press, yielding a finished block of lightweight core material having a honeycomb pattern of hex ducts with rigid walls.

Block-bonded process for producing thermoplastic resin impregnated fiber

An isostatic pressurizing bag for consolidating a composite part has an outer flexible elastomer having a fixed resilient outside surface. The outer elastomer surrounds a closed chamber. A thermally expandable inner elastomer is located in the closed chamber. The inner elastomer is selected as an elastomer that can viscously flow or move in response to pressure. The outer elastomer is capable of flexure to relieve expansion of the inner elastomer. The bag is formed by curing plies of uncured silicone rubber around either a silicone gel or a particulated silicone rubber that is capable of phase change to a flowable gel in response to pressure. In use a composite prepreg is overlaid on a surface that defines the shape of a desired part. The isostatic pressurizing bag is located over the prepreg trapping the prepreg between the pressurizing bag and the surface. The composite prepreg is heated to its cure temperature while simultaneously applying heat and pressure to the isostatic pressurizing bag to consolidate the prepreg between the surface and the isostatic pressurizing bag.

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Camarillo, CA, United States of America

John E Potter