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US 4,379,013 AGranted
Fine film pressure bags forming composite structures
AssigneeThe Boeing Company
InventorWilliam C. Tambussi
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AssigneeThe Boeing Company
InventorWilliam C. Tambussi
Estimating the term…
This invention relates to a method and apparatus for fabricating a composite structure and, in particular, to a method and apparatus for fabricating a hollow composite structure having a dense laminated wall formed by bonding and curing a plurality of resin-preimpregnated fiber sheets or tapes under heat and pressure. Hollow composite structures may be formed by applying layers of resin-impregnated fabric material onto a pressure bag covering a rigid mandrel, disposing the assembly of the mandrel, pressure bag, and uncured composite layers within an outer mold, transmitting heat to the composite material to cure the resin and applying pressure within the flexible pressure bag to act against the composite material during the curing operation to assure proper dimensions, density, structural properties and wall thickness of the cured composite structure.
In an apparatus for curing a tubular composite structure of laminated, resin-impregnated fibrous material which includes structure retaining means having a contoured inner surface adjacent the outer surface of the composite structure and pressure bag means disposed within and extending between opposite ends of the composite structure, for applying pressure to the inner surface of the composite structure, the improvement wherein the pressure bag means comprises at least one pressure bag formed of a material having inherent release characteristics and adapted to be connected to a pressure source, and the pressure bag includes at least one overlapped folded portion extending between the opposite ends of the adjacent composite structure, to allow the pressure bag to expand radially against the inner surface of the composite structure when the pressure bag is connected to the pressure source.
In an expandable pressure bag assembly for continuously applying pressure to the inner surface of a tubular composite structure during curing of the composite structure, which is closely disposed about a rigid mandrel and is adapted to be connected to a pressure source, wherein the pressure bag assembly includes an outer layer of a material having inherent release characteristics, about which contoured straps of layered, resin-impregnated fibrous material are disposed to form the composite, structure, the improvement wherein the pressure bag assembly comprises:
In a method for curing a tubular composite structure which includes the steps of forming an elongated mandrel assembly comprising a rigid mandrel and an expandable pressure bag assembly which is closely disposed about the mandrel, has an outer layer of material having inherent release characteristics and is adapted to be connected to a pressure source, laying contoured straps of layered, resin-impregnated fiber material about the mandrel assembly to form the uncured composite structure, disposing an outer mold or die assembly having a contoured inner surface about the uncured composite structure, and simultaneously applying heat and pressure to the composite structure for a predetermined time to effect curing thereof, which includes connecting the expandable pressure bag assembly to the pressure source to effect continuous application of pressure to the inner surface of the composite structure during curing thereof, the improvement wherein the step of forming an elongated mandrel assembly includes:
Dependencies are inferred from the claim text.