Appeal No. 2002-0963
Application No. 08/122,344
process was designed to utilize the advantages of both processes.
Page 2, col. 1. Specifically (page 2, cols. 1 and 2):
The fiber placement process has the features necessary
for producing complex shapes made from unidirectional
composite materials. The fiber placement process is a
unique method of laminating prepregged fiber materials
onto a complex mandrel or mold. . . . The basic
concept behind fiber placement is to combine the
differential tow payout speeds of filament winding with
the compaction and cut-restart features of tape laying.
. . . [D]ifferential payout allows each tow to
independently conform to the surface of a complex
shape, compaction allows the material to be laminated
with less entrapped air, and individual fiber cut-
restart makes a variable band width possible.
Evans describes "compaction" as follows (page 4, col. 2):
Compaction is the action of mechanically pressing the
tows onto the part or mold surface so entrapped air and
inner band gaps are removed from the band width. . . .
In most situations it is necessary to introduce heat
into the compactor nip area to decrease the resin
viscosity of the tows. This part of the process is
referred to as tack enhancement. Heat promotes resin
flow thus enabling the compactor to remove gaps between
adjacent tows easier. Increased tack also enables the
incoming fibers to adhere more quickly and remain in
place on the mold or previously laid courses.
Thus, Evans discloses that applying heat during compaction
enhances tack and enables the tows to adhere to the mold surface
more effectively. However, Evans does not suggest passing the
tows through a preheating zone of a fiber placement apparatus
prior to compaction.
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