# US 8,465,241 B2 · Composite fasteners containing multiple reinforcing fiber types

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- Number: US 8,465,241 B2
- Document ID: US8465241B2
- Status: Granted
- Kind: B2
- Application number: 11/932,186
- Filed: 2007-10-31
- Published: 2009-04-30
- Granted: 2013-06-18
- Earliest claimed: 2007-10-31
- Assignees: The Boeing Company
- Applicants: Kevin O. Gaw; Randall A. Rogers
- Inventors: Kevin O. Gaw; Randall A. Rogers
- Web page: https://patentgrep.com/patent/US8465241B2

## CPC

- B29C 70/083: {Combinations of continuous fibres or fibrous profiled structures oriented in one direction and reinforcements forming a two dimensional structure, e.g. mats (B29D24/00, B29D99/001 take precedence)}
- B29C 70/70: Completely encapsulating inserts {(B29C70/86 takes precedence)}
- F16B 33/006: {Non-metallic fasteners using screw-thread}
- B29C 35/0888: {using transparant moulds}
- B29C 45/14631: {Coating reinforcements (fibre reinforcements B29C45/0005)}
- B29C 70/882: {partly or totally electrically conductive, e.g. for EMI shielding (conductive floors or floor coverings H05F3/025; EMI shielding in general H05K9/00)}
- B29C 2035/0827: {using UV radiation}
- B29L 2031/727: {Fastening elements (bolts B29L2001/002; nuts B29L2001/005; screws B29L2001/007; slide fasteners B29L2005/00; buttons for haberdashery B29L2019/00)}
- Y10T 428/24994: Fiber embedded in or on the surface of a polymeric matrix
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- F16B: DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING (couplings for transmitting rotation F16D)
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method for making composite fasteners includes the provision of a mold containing an elongated cavity having a long axis and the shape of the fastener body, an elongated insert comprising a plurality of long, interwoven or intermingled first reinforcing fibers, and a hardenable liquid matrix that may include a plurality of short, second reinforcing fibers suspended therein. The insert is placed in the cavity such that the long reinforcing fibers are disposed generally parallel to the long axis of the cavity. The mold cavity is then filled with the liquid matrix such that the short reinforcing fibers are distributed generally uniformly throughout the mold cavity, and the liquid matrix of the suspension is then hardened so as to form a hardened fastener body encapsulating the first and second reinforcing fibers. The molded fastener is then removed from the mold, either for immediate use or for subsequent processing.

## Claims

### Claim 1

A composite fastener, comprising:
a molded polymer body comprising an elongated shank portion and a radially enlarged head portion disposed concentrically on one end of the shank portion;
an elongated fibrous insert encapsulated within the fastener body and extending between opposite ends thereof, the insert comprising a plurality of interwoven first reinforcing fibers, each having a length about as long as the fastener body and distinct opposite ends respectively spaced inwardly from the corresponding opposite ends thereof; and,
a plurality of second reinforcing fibers encapsulated within the fastener body, the second reinforcing fibers having a length substantially less than the length of the first reinforcing fibers and being distributed generally uniformly throughout the fastener body and intermingled with the longer fibers of the fibrous insert.

### Claim 2 (depends on 1)

The composite fastener of claim 1, further comprising a helical thread disposed on an outer surface of at least a part of the shank portion.

### Claim 3 (depends on 1)

The composite fastener of claim 1, wherein the head portion has a circular or a polygonal cross section transverse to a long axis of the fastener.

### Claim 4 (depends on 1)

The composite fastener of claim 1, wherein the head portion includes a feature adapted to be engaged by a tool.

### Claim 5 (depends on 1)

The composite fastener of claim 1, wherein at least one of the first and second reinforcing fibers comprises an electrically conductive fiber.

### Claim 6 (depends on 1)

The composite fastener of claim 1, wherein at least one of the tensile strength and/or the shear strength of the fastener is variable along at least one of the length and/or the radius of the fastener.

### Claim 7 (depends on 1)

The composite fastener of claim 1, wherein thermal conductivity of the fastener is variable along the length or radially.

### Claim 8 (depends on 1)

The composite fastener of claim 1, wherein the electrical conductivity of the fastener is variable along the length or radially.

### Claim 9 (depends on 1)

A method for manufacturing the composite fastener of claim 1, the method comprising:
providing a mold containing an elongated cavity having a long axis and the shape of a fastener to be molded therein;
providing an elongated insert comprised of a plurality of interwoven first reinforcing fibers having a length about as long as the cavity and distinct opposite ends;
providing an uncured liquid suspension comprising a liquid matrix in which a plurality of
second reinforcing fibers are suspended, the second reinforcing fibers having a length substantially less than the length of the first reinforcing fibers;
opening the mold;
placing the insert in the cavity such that the first reinforcing fibers are disposed generally parallel to the long axis of the cavity and their distinct opposite ends are respectively spaced inwardly from corresponding opposite ends of the cavity;
closing the mold;
filling the cavity of the mold with the suspension such that the second reinforcing fibers are distributed generally uniformly throughout the cavity and the opposite ends of the first reinforcing fibers remain respectively spaced inwardly from the corresponding opposite ends of the cavity;
hardening the liquid matrix of the suspension in the mold so as to form a hardened fastener body completely encapsulating the first and second reinforcing fibers therein;
opening the mold; and,
removing the molded fastener from the mold.

### Claim 10 (depends on 9)

The method of claim 9, wherein the insert comprises an annular sleeve having an axial lumen, and wherein the filling of the cavity with the liquid suspension comprises infiltrating the lumen of the sleeve with the liquid suspension such that the sleeve is expanded radially toward the wall of the mold cavity by the pressure of the liquid suspension.

### Claim 11 (depends on 10)

The method of claim 10, wherein the insert further comprises a plurality of third reinforcing fibers disposed axially in the lumen of the sleeve, the third reinforcing fibers having a length about as long as the sleeve.

### Claim 12 (depends on 9)

The method of claim 9, wherein the insert comprises a cylindrical bundle of the first reinforcing fibers.

### Claim 13 (depends on 9)

The method of claim 9, wherein at least one of the first and second reinforcing fibers comprises glass, carbon, boron, boron nitride (BN), beta carbon nitride (CN) or aluminum oxide (Al2O3).

### Claim 14 (depends on 9)

The method of claim 9, wherein the liquid matrix comprises a thermosetting resin or a thermoplastic resin.

### Claim 15 (depends on 14)

The method of claim 14, wherein the thermosetting resin comprises epoxy, polyimide, polyacrylic, polyamides or a cross linkable resin.

### Claim 16 (depends on 14)

The method of claim 14, wherein the thermoplastic resin comprises a thermoplastic resin, polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherimide, polyimide, polycarbonate, polyester, polysulfone, polyU-rethane or a polyamide.

### Claim 17 (depends on 9)

The method of claim 9, wherein the liquid matrix comprises water, and further comprising displacing the water with a hydrophilic, polymerizable liquid monomer or polymer before the hardening of the liquid matrix.

### Claim 18 (depends on 9)

The method of claim 9, wherein the liquid matrix comprises a liquid hydrocarbon, and further comprising displacing the liquid hydrocarbon with a lipophilic polymerizable liquid monomer or polymer before the hardening of the liquid matrix.

### Claim 19 (depends on 9)

The method of claim 9, wherein the hardening of the liquid matrix comprises:
hardening the matrix to a first hardness that is less than a final hardness; and,
then hardening the matrix to the final hardness.

### Claim 20 (depends on 19)

The method of claim 19, wherein the hardening of the matrix to the first hardness is effected in the cavity of the mold and the hardening of the matrix to the final hardness is effected after the fastener is removed from the mold.

### Claim 21 (depends on 9)

The method of claim 9, wherein the hardening of the liquid matrix comprises cross-linking the molecules of the liquid matrix.

### Claim 22 (depends on 9)

The method of claim 9, wherein the hardening of the liquid matrix comprises heating the liquid matrix, irradiating the liquid matrix with radiation, oxidizing the liquid matrix, mixing a catalyst with the liquid matrix, injecting a multipart polymerizable liquid matrix through different ports of the mold, or mixing components of the liquid matrix before filling the mold with the liquid matrix.

### Claim 23 (depends on 9)

The method of claim 9, wherein the filling comprises:
positioning an end of a nozzle at a first end of the cavity; and,
injecting the liquid suspension through the nozzle and into the cavity while simultaneously withdrawing the nozzle from the cavity such that any gas present within the cavity is expelled at a second end of the cavity and no gas pockets are entrapped within the liquid suspension.