Electromagnetic effect protective fastener with frangible collar

Patent metadata

Field	Value
Publication number	US-10626908-B2
Application number	US-201815941425-A
Country	US
Kind code	B2
Filing date	Mar 30, 2018
Priority date	Mar 30, 2018
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

An electromagnetic effect suppressing termination part is provided for a fastener formed of a metallic material, the fastener having a head, a shank, and a threaded portion opposite the head. The termination part includes a main body defining an internally threaded portion configured to threadably receive the threaded portion of the fastener, the internally threaded portion defining a thread major diameter. A collar is coupled to a distal end of the main body by a frangible web, wherein the main body, collar, and frangible web are formed of a metallic core coated by a layer of dielectric material. The frangible web, when broken, presents an exposed portion of the metallic core, wherein the frangible web includes an inner surface radially outwardly offset from the thread major diameter of the internally threaded portion by a setback distance.

First claim

What is claimed is:

1. An electromagnetic effect suppressing termination part for a fastener formed of a metallic material, the fastener having a head, a shank, and a threaded portion opposite the head, the termination part comprising:
a main body defining an internally threaded portion configured to threadably receive the threaded portion of the fastener, the internally threaded portion defining a thread major diameter; and
a collar coupled to a distal end of the main body by a frangible web;
wherein the main body, collar, and frangible web are formed of a metallic core coated by a layer of dielectric material;
wherein the frangible web when broken presents an exposed portion of the metallic core, the frangible web including an inner surface radially outwardly offset from the thread major diameter of the internally threaded portion by a setback distance, the setback distance being approximately 0.5 mm or greater.

2. The electromagnetic effect suppressing termination part of claim 1 , in which the setback distance is sufficient to prevent arcing between the exposed portion of the metallic core and the threaded portion of the fastener.

3. The electromagnetic effect suppressing termination part of claim 1 , in which the shank of the fastener has a shank diameter, and in which the setback distance is approximately 1/25 to ¼ of the shank diameter.

4. The electromagnetic effect suppressing termination part of claim 1 , in which the main body further defines a proximal end nearer the head of the fastener, and a counterbore hole is formed in the proximal end, wherein an annular seal is disposed in the counterbore hole.

5. The electromagnetic effect suppressing termination part of claim 4 , in which the annular seal is formed of a polymeric material.

6. The electromagnetic effect suppressing termination part of claim 4 , further comprising a washer located adjacent the proximal end of the main body.

7. The electromagnetic effect suppressing termination part of claim 1 , in which the frangible web is configured to break at a predetermined torque threshold.

8. A fastener assembly for protection against electromagnetic effects, the fastener assembly comprising:
a fastener formed of a metallic material and having a head, a shank, and a threaded portion opposite the head;
a termination part having a metallic core coated by a layer of dielectric material, the termination part including:
a main body defining an internally threaded portion configured to threadably receive the threaded portion of the fastener, the internally threaded portion defining a thread major diameter;
a collar coupled to a distal end of the main body by a frangible web, wherein the frangible web when broken presents an exposed portion of the metallic core, the frangible web including an inner surface radially outwardly offset from the thread major diameter of the internally threaded portion by a setback distance, the setback distance being approximately 0.5 mm or greater.

9. The fastener assembly of claim 8 , in which the setback distance is sufficient to prevent arcing between the exposed portion of the metallic core and the threaded portion of the fastener.

10. The fastener assembly of claim 8 , in which the shank of the fastener has a shank diameter, and in which the setback distance is approximately 1/25 to ¼ of the shank diameter.

11. The fastener assembly of claim 8 , in which the main body further defines a proximal end nearer the head of the fastener and a counterbore hole is formed in the proximal end, the fastener assembly further comprising an annular seal disposed in the counterbore hole.

12. The fastener assembly of claim 11 , in which the annular seal is formed of a polymeric material.

13. The fastener assembly of claim 11 , further comprising a washer located adjacent the proximal end of the main body.

14. The fastener assembly of claim 8 , in which the frangible web is configured to break at a predetermined torque threshold.

15. The fastener assembly of claim 8 , further comprising:
a first structural member having a first through hole; and
a second structural member having a second through hole aligned with the first through hole;
wherein the shank of the fastener extends through the first and second through holes.

16. The fastener assembly of claim 15 , in which each of the first and second structural members is formed of a composite material.

17. The fastener assembly of claim 15 , in which each of the first and second structural members is formed of a metallic material.

18. A method of fastening a structural assembly while suppressing electromagnetic effects, the method comprising:
inserting a fastener formed of a metallic material through a first structural member so that a shank of the fastener extends through a first through hole formed in the first structural member, the fastener including a threaded portion;
threading a termination part having a metallic core coated by a layer of dielectric material onto the fastener, the termination part having a main body defining an internally threaded portion configured to threadably receive the threaded portion of the fastener, the internally threaded portion defining a thread major diameter;
applying torque to a collar of the termination part until a frangible web connecting the collar to a distal end of the main body of the termination part breaks, wherein the frangible web when broken presents an exposed portion of the metallic core, the frangible web including an inner surface radially outwardly offset from the thread major diameter of the internally threaded portion by a setback distance, the setback distance being approximately 0.5 mm or greater.

19. The method of claim 18 , in which the setback distance is sufficient to prevent arcing between the exposed portion of the metallic core and the threaded portion of the fastener.

20. The method of claim 18 , in which the shank of the fastener has a shank diameter, and in which the setback distance is approximately 1/25 to ¼ of the shank diameter.

Assignees

• Boeing Co

Inventors

• Morden Sean D
• Simpson Blake A
• Sisco Tanni
• Chan Kwok-Tung
• Brockway Monica J

Classifications

• F16B31/021 Primary

  by means of a frangible part (F16B31/025, F16B31/028 take precedence; break members in torque limiters or torque indicators in wrenches or screwdrivers B25B23/1415) · CPC title

• B64D45/02

  Lightning protectors; Static dischargers · CPC title

• F16B33/06

  Surface treatment of parts furnished with screw-thread, e.g. for preventing seizure {or fretting (corrosion preventing means F16B33/008; settable coatings for locking threaded members F16B39/225; deformable coatings for locking threaded members F16B39/34)} · CPC title

• F16B37/14

  Cap nuts; Nut caps or bolt caps · CPC title

• F16B33/004

  Sealing; Insulation (by means of washers F16B43/001) · CPC title