# US 4,718,801 A · Composite core fastener

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- Number: US 4,718,801 A
- Document ID: US4718801A
- Status: Granted
- Kind: A
- Application number: 06/888,700
- Filed: 1986-07-24
- Granted: 1988-01-12
- Earliest claimed: 1986-07-24
- Assignees: Microdot Inc.
- Inventors: Imre Berecz
- Web page: https://patentgrep.com/patent/US4718801A

## CPC

- B64D 45/02: Lightning protectors; Static dischargers
- F16B 33/006: {Non-metallic fasteners using screw-thread}
- Y10S 411/90: Fastener or fastener element composed of plural different materials
- Y10S 411/901: Core and exterior of different materials
- Y10S 411/904: Fastener or fastener element composed of nonmetallic material
- Y10S 411/908: Resinous material
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- 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)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A fastener comprises composite head and shank portions having an encapsulating metal sheath thereon that is electrically isolated from conductive fibers in the head and shank portions and from an exposed surface of the head portion.

## Claims

### Claim 1

A fastener comprising a composite core having an enlarged head portion at one end and a shank portion at the other end said head portion being of a diameter greater than that of said shank portion, and a metal sleeve encapsulating the shank portion of said core and a portion of the head portion and an outer surface of said sleeve being threaded for the acceptance of a nut, said metal sleeve being spaced axially from an axial end face of the head portion whereby said metal sleeve is electrically isolated from the end surface on the head portion of said fastener.

### Claim 2 (depends on 1)

A composite core fastener in accordance with claim 1 wherein said core comprises a plurality of electrically conductive fibers electrically isolated from one another and from said metal sleeve by a nonconductive resin matrix.

### Claim 3

A composite core fastener comprising an inner composite core having an enlarged head portion at one end and a shank portion at the other end said head portion being of a diameter greater than that of said shank portion, a metal sleeve encapsulating the shank portion of said fastener and a portion of the head portion thereof, said metal sleeve terminating below an upper end surface of the head portion of said fastener, and a nonconductive sheath interposed between the composite shank portion and metal sleeve of said fastener to further electrically isolate said metal sleeve from the upper end surface of the head portion of said fastener and an outer surface of said sleeve being threaded for the acceptance of a nut.