Plastic and nonmetallic article shaping or treating: processes – Vacuum treatment of work – To degas or prevent gas entrapment
Reexamination Certificate
1999-05-18
2001-10-09
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Vacuum treatment of work
To degas or prevent gas entrapment
C264S103000, C264S137000, C264S152000, C264S162000, C264S257000, C264S258000, C264S314000, C264S315000
Reexamination Certificate
active
06299810
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to the manufacture of composites. In particular, the present invention relates to the manufacture of composites formed from a series of carbon fibers woven together and treated with a resin material to form a weave or sample that is then vacuumed, compressed, and cured to form a substantially solid carbon fiber composite for forming various products each having a unique, non-uniform, decorative appearance.
BACKGROUND OF THE INVENTION
Composite materials are increasingly being used for the manufacture of a variety of products and as building materials due to their high strength and durability and the ability to easily manufacture and machine such composites into a variety of shapes and designs. Carbon-based composites such as carbon fiber composites especially are becoming increasingly popular for use in numerous industrial applications for their high strength and stability. For example, carbon fiber composites are now being used in a variety of products such as the wings and bodies of high technology jet fighter airplanes, automobile dashboards, and smaller articles such as billiard cues.
In current industrial processes, carbon fiber composites typically are formed by winding a series of fibers about a mandrel as a resin material is applied, or by mixing the fibers and resin in a mold. The resultant sample or weave of carbon fibers is then compressed under extremely high pressures and temperatures to press the carbon fiber and resin weave or sample into a substantially solid block, and to cause the resin to cure and harden to form a substantially solid carbon fiber composite. It is critical in such industrial processes that the resultant composite materials being formed be uniform in cross-section such that the carbon fibers are required to be wound or formed with a-prescribed pattern or grain in order to preserve the strength and structural integrity of the resultant composites. Uniformity, and thus strict adherence to a prescribed pattern, is especially critical for materials used in such applications as airplane wings.
Accordingly, a high degree of precision in the winding of the carbon fibers in a specific pattern without deviation is necessary to insure the uniformity of the composite material required by conventional industrial processes. Such uniformity and adherence to a prescribed pattern results in the composites formed thereby having a substantially uniform, precise patterned appearance. Thus, such carbon fiber composites primarily are used for larger products where structural integrity is of primary concern rather than forming articles having a highly unique, decorative appearance. In addition, the pressures exerted during compression of the carbon fiber and resin sample or weave in most conventional processes generally are extremely high. Even with such high pressures and temperatures, and long cure times, most industrial processes for forming carbon fiber composites typically have as much as 50% waste or unusable material due to the failure to exhaust all air from within the carbon fiber weave, and/or to thoroughly wet the fibers.
Attempts also have been made to use a vacuum within an autoclave or pressure chamber to draw out air from within the carbon fiber weave before compressing the wo und, resin-covered fiber weave. An additional process is believed to be disclosed in the pending U.S patent application of Harold Hale, application Ser. No. 08/786,784, entitled “Method and Apparatus for Manufacture of Minimum Velocity, Wrike Free Composite Parts”, which is believed to disclose the use of manufacturing composite parts in which the composite materials are encased in a vacuum bag placed in a vacuum chamber, and then a vacuum drawn on both the bag and the chamber to first draw out air from within the carbon materials and thereafter to apply pressure to the materials. While such a process appears to provide for higher quality composite products, there is still significant waste that occurs, although not on the same order as current conventional manufacturing processes. In addition, this vacuum bag method frither requires great care and precision in bagging and sealing the carbon fiber and resin weave or sample within the bag and placing the bag within the vacuum chamber, as, if the bag is not sealed or is punctured or has any defects at all, the sample will be ruined and must be discarded.
Accordingly, it can be seen that a need exists for a system and method of forming composite materials, such as carbon fiber composites, that enables a carbon fiber composite to be formed efficiently and relatively inexpensively, with the amount of waste being significantly reduced, and which firther provides the resultant carbon fiber composite with an enhanced, unique, non-uniforn, highly decorative appearance.
SUMMARY OF THE INVENTION
Briefly described, the present invention comprises a system and method for forming a carbon fiber composite material having a random, non-uniform, decorative and unique appearance for use in forming a variety of products from tabletops and flooring tiles to urns and cigar humidors.
In a first embodiment of the invention, a series of carbon fibers are fed from a creel to a lathe of a winding assembly. The size or tow of the carbon fibers typically is in the range of 1,000 to 50,000 (i.e. 1,000 to 50,000 individual strands per bundle or tow) and generally between 5 to 20 spools are used to feed fibers of varying sizes to the winding assembly. The winding assembly includes a lathe having an elongated collection trough or basin, and a carriage that is reciprocably movable along the length of the trough. The carbon fibers are fed to the carriage, which includes a wetting jig under which the fibers are passed for applying a resin material to the fibers. The resin material flows through drip openings in the wetting jig and onto the fibers, substantially coating or soaking the fibers with the resin material. The carriage is mounted along a track that extends along the length of the lathe to enable the carriage to be reciprocably movable longitudinally along the length of the lathe. A carriage motor such as a servo motor or similar variable speed reversible motor is mounted at one end of the track to control the movement of the carriage therealong and is linked to a computer control which can be programmed to vary the speed and movement of the carriage along the track, as well as to cause the cariage to pause randoml y dur ing its travel along the length of the lathe.
The lathe further includes a main rotary drive motor mounted at the head-stock end of the lathe. The main drive motor typically is a variable speed reversible electric motor, such as a servo motor, and is inked to the same computer control for the carriage motor, which controls the motor so as to operate the drive motor at varying speeds. A mandrel is received within the collection trough, connected to the drive shaft of the drive motor and is rotated by the main rotary drive motor. The mandrel generally is approximately 12 to 20 feet in length and approximately 14 to 65 inches in width, although mandrels of other, varying sizes also can be used as desired. The mandrel generally includes an outer skin or side wall and first and second ends, mounted to the drive shaft and an idler shaft of the lathe, respectively. Heating elements such as heating tapes are generally mounted within the mandrel for internally heating the skin of the mandrel during curing of the resin material. A release agent such as a plastic film, including a nylon or polyethylene film or a non-stick coating such as a water or oil-based spray solvent-based silanes, and organic waxes, or similar agent is applied to the skin of the mandrel, covering the skin and the first and second ends of the mandrel to prevent the resin material from adhering to the mandrel as the carbon fibers are wound thereabout.
As the mandrel is rotated by the lathe, the carbon fibers, with the resin material applied thereto, are wound about the mandrel as the carriage is moved longitudinal
Michael RiCharde, LLC
Silbaugh Jan H.
Staicovici Stefan
Womble Carlyle Sandridge & Rice PLLC
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