Apparatus and methods for producing tow based patterns

#The invention relates to the field of equipment and methods for the fabrication of composite structures and, more specifically, to equipment and methods for the fabrication of tow-based patterns.

#The use of polymer composites continues to grow at approximately 11-14% per annum, largely driven by the aerospace industry and more recently by the sporting goods and private transportation industries. The desire for lightweight, environmentally safe and resilient vehicles and structural materials continues to stimulate this growth. One can generally divide composite processes into two categories: those processes involving pre-impregnated materials (prepreg) and those involving “wet” fabrication.

#Prepreg involves the dispersal of a partially cured resin on a lamina of unidirectional or woven fiber material. In general prepregs consist of surface treated glass, graphite, or aramid fibers impregnated with 28-60 weight percent of a reactive and chemically complex thermoset resin formulation or a thermoplastic resin. Prepreg suppliers usually deliver prepreg material as a roll requiring refrigeration until a composite manufacturer needs the material. A composite structure manufacturer subsequently unrolls the material, cuts the material to size, and stacks the cut material to create the desired composite structure. The composite structure manufacturer uses an autoclave or heated press to supply the necessary heat and pressure for cure and consolidation.

#For a better understanding of the present invention, reference is made to the drawings, which are incorporated by reference and in which:

#FIG. 1 is a perspective view of one embodiment of a tow-based preform manufacturing apparatus according to the present invention;

#FIG. 2 illustrates a roll of fabric for use in existing preform processes;

#The present invention provides systems and methods capable of creating inexpensive, custom, complex, tow-based patterns at a variety of volumes with low scrap rates. Manufacturers can use the patterns to form a complete part laminate or they can combine one or more patterns with one or more other patterns to create a complete part laminate. Manufacturers can use a pattern or group of patterns, produced using embodiments of the invention, in a liquid molding process to obtain a molded part. The liquid molding process can be one of a variety of liquid molding processes such as RTM, VARTM, or Compression

#For present purposes, the term “tow” means a loose untwisted rope of filaments, which may include graphite, glass, aramid or other filaments, for use in reinforcement of plastic composite parts. The term “tow” includes yarns, which are multiple tows.

#With reference to FIG. 1, one embodiment of the present invention provides apparatus 20 for producing tow-based patterns. Apparatus 20 includes a support structure 23 supporting an X-Y gantry 26, such as a XY gantry available from Macron Dynamics of Horsham, Pa. Two servo motors and one multi-axis controller such as the MX-2000 by Superior Electric of Bristol, Conn. drive the X-Y gantry. The X-Y gantry can be a conventional XY gantry such as the XY gantry described in U.S. Pat. No. 4,735,672, entitled “Automated Fiber Lay-Up Machine” and incorporated herein by reference in its entirety.