US 5,242,523 AGranted

Caul and method for bonding and curing intricate composite structures

AssigneeThe Boeing Company

InventorsKurtis S. Willden, Kenneth N. Goodno

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Abstract

The invention disclosed here is a method for forming and curing an intricate structure of criss-crossing composite stringers and frames that are bonded to a skin panel. A structure constructed in accordance with the invention would be well-suited for use as a portion of an aircraft fuselage, a boat hull, or the like. The method is preferably practiced by applying uncured composite stringers to an uncured composite sheet panel. This is followed by placing cured frames crosswise over the stringers. The frames have openings at the locations where they intersect with the stringers which enables the frames to come into direct contact with the skin along most of their length. During the forming and curing process, the stringers are covered with a plurality of cauls, and the entire assembly of skin panel, stringers, frames and cauls is subjected to a vacuum bagging and curing process. The cauls serve to maintain both part shape and to control the flow of resin within the stringers as they are cured. Further, they probably eliminate the need for intermediate protective materials between the vacuum bag and the stringers.

A method for making a structural panel solely from composite materials, comprising:

placing a skin panel upon a tooling surface, wherein said skin panel is made of a composite material;
laying a plurality of stiffeners across said skin panel, with a layer of a bonding substance being positioned between and substantially along the length of contact of each stiffener with said skin panel, and wherein all of said stiffeners are made of a composite material;
laying a plurality of frame members across said skin panel crosswise of said stiffeners, wherein all of said frame members are made of a composite material and have openings sized to receive at least portions of said stiffeners which intersect said frame members, in a manner so that a majority of the length of each frame member directly contacts said skin panel, said frame members being spaced apart in a manner so as to define a stiffened panel section between every two frame members laid across said stiffeners, and with a layer of a bonding substance being positioned between and substantially along the length of contact of each frame member with said skin panel;
placing a plurality of cauls over said stiffeners, including placing a single caul over at least a portion of each stiffened panel section, said cauls defining the outer part shape of substantially all portions of said stiffeners which underlie said cauls;
placing a vacuum bag over the above assembly of said frame members, said cauls, said underlying stiffeners, and said skin panel;
followed by
evacuating said bag in a manner so that said bag presses said frame members against said skin panel and simultaneously presses against said cauls, consequently causing said cauls to press said stiffeners against said skin panel, and heat-curing said assembly to simultaneously cure said stiffeners and said skin panel, and to simultaneously bond said stiffeners and frame members to said skin panel, to thereby form said structural panel.

4 more elements

Facts

Application

07/882,831Filed 14 May 1992

Granted

7 Sep 1993

Term ends

Not estimatedThe source records don’t support an estimate.

Classification13 codes

B64C 1/12
Frames; Stringers; Longerons ; Fuselage sections: construction or attachment of skin panels
B29C 70/44
For producing articles of definite length, i.e. discrete articles: using isostatic pressure, e.g. pressure difference-moulding, vacuum…
B29C 70/549
Component parts, details or accessories; Auxiliary operations , e.g. feeding or storage of prepregs or SMC after impregnation or during ageing:…
B29D 99/0014
Producing wall or panel-like structures, e.g. for hulls, fuselages, or buildings: provided with ridges or ribs, e.g. joined ribs

Abstract

Claims10