Appeal No. 1997-2840
Application No. 08/265,971
APPENDIX
5. A method for joining a plurality of layers of non-
fully cured composite material, including layers comprising a
polymeric matrix having a curing temperature range and having
a plurality of reinforcing fibers disposed therein, the layers
being superimposed to define a single airfoil shape, the
method comprising the steps of:
debulking the airfoil shape by first providing a vacuum
about the shape to remove entrapped gas from and between the
layers and then pressurizing and heating the shape to precure
the polymeric matrix and to inhibit relaxation of the
composite material during subsequent processing, thereby to
provide a preliminary, debulked, precured, airfoil preform
having a near net shape configuration of a final article;
generating a plurality of spaced apart holes, each
defined by a hole wall, through the superimposed layers of the
preliminary airfoil preform by penetrating a thin pointed tool
into and through the preform using ultrasonic energy applied
into the tool such that motion of the tool is limited to
vibration in a direction substantially normal to the surface
of the preform, the ultrasonic energy being applied at a rate
which causes the polymeric matrix to at least soften as a
result of heat generated from damping of the ultrasonic energy
locally in the polymeric matrix adjacent the tool, whereby
upon withdrawal of the tool from the hole and cooling of the
polymeric matrix at the hole wall, the hole wall is provided
with a smooth surface, and whereby the reinforcing fibers and
the integrity of the superimposed layers are substantially
unaffected;
fastening together the layers of the composite material
through the holes, using fiber members, to provide a debulked
airfoil preform, and then
curing the airfoil preform in the curing temperature
range to provide a cured, reinforced airfoil, the fiber
members being bonded to the airfoil at the hole walls.
1
Page: Previous 1 2 3 4 5 6 7 8
Last modified: November 3, 2007