Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-12-24
2001-11-20
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S245000, C156S285000, C029S889600, C244S123800, C264S258000, C416S226000, C416S230000
Reexamination Certificate
active
06319346
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
(Not applicable)
FIELD OF THE INVENTION
This invention relates to the manufacture of aircraft control surfaces, particularly spoilers, from fiber/resin composite materials.
BACKGROUND OF THE INVENTION
Traditionally, the construction of control surfaces for aircraft has been from lightweight metal alloys. For example, for spoilers, frame elements, hinges, actuation fittings and sheet metal have been machined and assembled using appropriate fasteners, such as welding or rivets. Since spoilers are subjected to torsion during use, they are usually made in the form of a torsion box. Because of the many parts that must be assembled, the manufacture of the spoiler by traditional methods requires several machining and assembly steps and is accordingly quite expensive. In addition, at each place where individual parts are attached, there is a potential for failure of the weld or rivet at joint, which increases the possibility of failure of the part.
Composite materials of a cured resin and a reinforcing fiber have been used for certain parts in aircraft construction. Composites have high strength, and are light in weight, both which are desirable for aircraft. However, the use of composites for control surfaces has been limited. This is due in part to the difficulty of making large composite parts of complex configuration while maintaining the strict quality requirements required for aircraft parts. This problem is aggravated by the requirement of the shape of the spoiler, which requires a thick leading edge of high strengths for mounting of hinges and actuation fittings that tapers down to a thin trailing edge that must be of appropriate aerodynamic design. Adhering several pre-manufactured parts with a thermosetting resin can make large assemblies of composite materials. However, this would introduce undesirable points of weakness at the joints of the part, and require precision machining and fitting of the parts. In addition, any machining to form the part into their final shape, either for assembly to another part or for the final aerodynamic shape, is undesirable, for such will cut reinforcing fiber. Accordingly, undesirable weight in the form of extra reinforcing fiber must be added to compensate for the machining and the inherent weakness at joints. These problems have prevented composites from becoming a competitive replacement for metals on these parts, particularly in the commercial market where manufacturing costs must be kept low, and the very high performance required for military supersonic aircraft is not necessary.
It is accordingly, a long felt need in the industry to provide a method for making control surfaces, such as spoilers, that is competitive with traditional metal-assembly methods of the manufacturing, while providing improvements in strength, weight, and simplification of the manufacturing process.
Incorporation but reference
U.S. patent application Ser. No. 09/441,356, filed Nov. 16, 1999, U.S. patent application Ser. No. 08/839,110, filed Apr. 23, 1997, now U.S. Pat. No. 5,985,197 and U.S. patent application Ser. No. 08/865,493 filed May 29, 1997, are hereby incorporated by reference.
Objects of the Invention
It is, therefore, an object of the invention to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that solves the above problems.
Another object of the invention is to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that is integral in construction, and requires a little of no assembly of separate parts.
Another object of the invention is a to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that forms a part near its final shape that requires a minimum of machining.
Another object of the invention is a to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that allows the properties of each portion of the spoiler, such the leading and trailing edges, to be optimized for strength and light weight.
Another object of the invention is a to provide a method for manufacturing an aircraft spoiler control surface of a fiber/resin composite material that permits a torsion box construction to optimize the light weight and torsion properties of the spoiler.
Further objects of the invention will become evident in the description below.
BRIEF SUMMARY OF THE INVENTION
The present invention is a process for manufacturing an aircraft spoiler control surface of a generally elongated shape with a teardrop cross-section with a thick leading portion and a thin trailing portion joined by a middle tapered portion, and with at least one metal actuator fitting, and at least one hinge lug cocured into the leading edge portion of the shape, the process comprising:
providing a female cavity mold with a lower half and an upper half, with an elongated molding cavity dimensioned essentially the same as and corresponding to outer surfaces of the elongated shape and extending in the direction of a longitudinal axis, with a corresponding leading portion, a tapered portion and a trailing edge portion;
placing a lower layer of multiple plies of resin impregnated fiber into the lower half of the female mold with a leading lateral edge in the leading portion, and a trailing lateral edge in the trailing portion;
wrapping multiple plies of resin impregnated fiber around a flexible, pressurizable bladder;
placing the wrapped bladder in the mold over the lower layer in the leading portion of the cavity;
placing the rigid mandrel in the mold over the lower layer in the tapered portion with the rigid mandrel and the wrapped bladder extending adjacent to one another and extending generally parallel to the longitudinal axis of the cavity;
placing a metal actuator fitting insert in the mold, the insert comprising a root portion and a head portion with the root portion extending through a lower actuator slot in the leading lateral edge of the lower layer;
placing a hinge lug ply stack in the mold, the hinge lug ply stack comprising a stack of plies of impregnated fiber with a root portion and a head portion with the root portion extending through an lower hinge lug slot in the lateral edge of the lower layer;
placing a upper layer over the wrapped bladder and the mandrel with a leading lateral edge in the leading portion and the trailing lateral edge in the trailing portion, and with the upper and lower layers overlapping at their leading lateral edges, and their trailing lateral edges adjacent to each other at the trailing end, the upper layer having respective upper actuator and upper hinge lug slots through with the metal actuator fitting insert and the hinge lug ply stack extend;
closing the female mold by placing the upper half over the lower half, such that the upper and lower layers are adjacent to inner molding surfaces of the cavity, the wrapped bladder extends through the leading edge portion of the cavity, the mandrel extends though the tapered portion of the cavity, each metal actuator fitting insert extends through the upper and lower actuator slots with its head disposed a cavity in the female mold and its root disposed between the overlying plies of upper and lower layers and underlying plies of wrapped bladder, each hinge lug ply stack extends through the upper and lower hinge lug slots with its head in compressible cavity in the female mold and its root extending through the upper and lower hinge slots and with at least a portion of plies from the root folded up between overlying plies upper and lower layers and underlying plies of wrapped bladder,
the plies of the upper and lower layers, and the plies wrapped around the bladder having fibers extending a generally +45° and a −45° orientation with respect to the longitudinal axis;
applying pressure upon the mold halves to compress that portion of the plies in the upper and lower layers adjacent to the mandrel between surfaces of the
Clark Paul
Garhart Jonathan
Milovich Dimitrije
Nelson Ronald
Aftergut Jeff H.
Radius Engineering, Inc.
Sonntag James Lawrence
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