Blind fastener for composite materials
AssigneeMonogram Industries, Inc.
InventorsJohn D. Pratt, Cu S. Huynh
Life of this patent
Estimating the term…
Abstract
A blind fastener particularly suited for mechanically joining composite structures such as graphite and fiber/epoxy matrix with a minimum of blind side damage. A first sleeve of highly ductile material is disposed as a liner about the portion of the nut which passes through the composite materials. The first sleeve extends longer than the thickness of the materials. A second sleeve of measurably less ductility is disposed between the first sleeve and the head of the threaded corebolt. The two sleeves have abutting surfaces which are non-sliding whereby as the nut and corebolt are threadily engaged and the two sleeves are brought into compression, the less ductile sleeve flairs the more ductile sleeve about the nut to create a protected area about the blind side of the materials.
Claims10
In a blind fastener having a nut with an internally threaded axial bore throughout with a generally conically shaped nose portion at one end and a head of larger diameter than said nose portion at the other end, and an intermediate generally cylindrical portion of lesser diameter than said head between the nose portion and the head, a corebolt having a head and a threaded shank portion, the threaded shank portion being threaded in the axial bore of the nut, the improvement which comprises:
- (a) a first expansible cylindrical sleeve having an internal diameter which is sized to create a sliding fit on the intermediate portion of the nut, said first sleeve being disposed on said intermediate portion in abuttment with a portion of the nut adjacent the head thereof;
- and,
- (b) a second expansible cylindrical sleeve having an internal diameter which is sized to create a sliding fit on the shank portion of the corebolt, said second sleeve being disposed on said shank portion between the head of the core bolt and said first sleeve, said second sleeve being adapted to perform in the manner of a less ductile material than said first sleeve, said first and second sleeves meeting in non-sliding abutting surfaces whereby as the nut and corebolt are threaded together compressive forces are transmitted through said second sleeve into said first sleeve to deform said first sleeve radially outward and back along the intermediate portion of the nut towards the head of the nut and said second sleeve is expanded primarily by the nose portion of the nut.
Dependencies are inferred from the claim text.