Block-bonded process for producing thermoplastic resin impregnated fiber

Abstract

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.