Method of assembling a structure using highly-deformable titanium and titanium-alloy one-piece fasteners

Patent metadata

Field	Value
Publication number	US-9649682-B2
Application number	US-201414569031-A
Country	US
Kind code	B2
Filing date	Dec 12, 2014
Priority date	Nov 17, 2011
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

A method of forming a fastener may include inserting a blank precursor into a bore of a forming die having an enlarged bore portion. The method may further include applying a first axial compression force to the blank precursor, and forming a cold-worked head section and an enlarged shank portion on the blank precursor corresponding to the enlarged bore portion. The enlarged shank portion may have a nominal shank portion extending therefrom. The method may additionally include inserting the nominal shank portion into a bore of a final reduction die, applying a second axial compression force to the enlarged shank portion, and urging the enlarged shank portion into the bore of the final reduction die. The method may also include reducing a cross-sectional area of the enlarged shank portion by approximately 2 to 5 percent to form a cold-worked shank section.

First claim

What is claimed is:

1. A method of assembling a structure, comprising the steps of:
providing a semi-tubular fastener formed from a semi-tubular blank precursor having a hollow tubular cavity, extending at least partially into the semi-tubular blank precursor and having an ultra-fine grain titanium or titanium-alloy composition having an average grain size of less than approximately 10 microns, the semi-tubular fastener having a head and a shank terminating at a tail end portion, the head comprising a cold-worked head section, the shank including a cold-worked shank section and a ductile shank section extending from the cold-worked shank section to the tail end portion, the cold-worked shank section being formed by reducing a cross-sectional area of an enlarged shank portion by approximately 2 to 5 percent while a shaft of an insert tool is inserted into the hollow tubular cavity, the cold-worked head section and the cold-worked shank section having a higher strength than the ductile shank section;
installing the semi-tubular fastener in a hole of the structure; and
upsetting the tail end portion of the ductile shank section.

2. The method of claim 1 wherein the cold-worked shank section is formed by reducing a cross-sectional area of the enlarged shank portion by approximately 3.5 percent.

3. The method of claim 1 wherein:
the structure has a thickness, the cold-worked shank section having a length that is substantially similar to the thickness of the structure.

4. The method of claim 1 wherein the semi-tubular fastener is a protruding head fastener and the step of installing the protruding head fastener comprises:
installing the protruding head fastener in a non-countersunk hole of the structure.

5. The method of claim 1 wherein the semi-tubular fastener is a flush head fastener and the step of installing the flush head fastener comprises:
installing the flush head fastener in a countersunk hole of the structure.

6. The method of claim 1 wherein:
the ductile shank section has a level of ductility that is higher than the level of ductility of the cold-worked head section and the cold-worked shank section.

7. The method of claim 1 further comprising the step of:
providing the semi-tubular fastener coated with a corrosion-resistant, curable organic coating material.

8. The method of claim 1 wherein the step of installing the semi-tubular fastener comprises:
installing the semi-tubular fastener in an aircraft structure.

9. The method of claim 1 wherein:
the ductile shank section of the semi-tubular fastener has a ductility value of at least 10 percent elongation along a longitudinal axis of the semi-tubular fastener prior to fracturing or failure of the ductile shank section.

10. The method of claim 1 wherein:
the ductile shank section of the semi-tubular fastener has a ductility level represented by a reduction in cross-sectional area of at least approximately 30 percent prior to fracturing or failure of the ductile shank section.

11. The method of claim 1 wherein:
the ultra-fine grain titanium or titanium-alloy composition has the average grain size of less than approximately 500 nanometers.

12. The method of claim 7 wherein:
the coating material comprises a phenolic resin.

13. The method of claim 1 wherein:
the semi-tubular fastener is annealed.

14. The method of claim 4 wherein:
the protruding head fastener is one of a protruding shear head fastener or a protruding tension head fastener.

15. The method of claim 4 wherein:
the structure has a thickness, the cold-worked shank section of the protruding head fastener has a length that is substantially equivalent to the thickness of the structure.

16. The method of claim 5 wherein:
the cold-worked head section and the cold-worked shank section of the flush head fastener have a combined length that is substantially equivalent to a length of the countersunk hole when the head is seated in the countersunk hole.

17. The method of claim 1 wherein upsetting the tail end portion of the ductile shank section comprises:
upsetting of the tail end portion using one of a rivet compression tool or a rivet crimping tool.

18. The method of claim 1 wherein upsetting the tail end portion of the ductile shank section comprises:
applying a series of impacts to the semi-tubular fastener.

19. The method of claim 18 wherein applying the series of impacts to the semi-tubular fastener comprises:
applying the series of impacts using a rivet gun disposed against the head of the semi-tubular fastener and a bucking bar disposed against the tail end portion of the semi-tubular fastener.

Assignees

• Boeing Co

Inventors

• Keener Steven G

Classifications

• B21J15/02 Primary

  Riveting procedures · CPC title

• B21K1/60 Primary

  hollow or semi-hollow rivets · CPC title

• F16B5/04

  by means of riveting (rivets F16B19/04) · CPC title

• F16B19/06

  Solid rivets made in one piece · CPC title

• Y10T29/49956

  Riveting · CPC title