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US 4,230,016 AGranted
Fatigue resistant fastener and method of manufacturing joints therewith
AssigneeThe Boeing Company
InventorHollis B. Merrell
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AssigneeThe Boeing Company
InventorHollis B. Merrell
Estimating the term…
An improved interference fit, fatigue-rated pin-type, nondeformable fastener and joints formed thereby are disclosed in countersunk flush head and protruding flat head embodiments, each characterized by a straight interference fit shank with a lead-in convex shoulder adjacent its threaded end operable to cold work the wall material of the straight fastener hole during fastener insertion, and with the shank progressively expanded in a concave curvilinear profile to its head end starting at a location preferably intermediate the ends of the shank. Curvature of the expansion profile fairs smoothly at relatively large radius into the straight intermediate portion of the shank. At its opposite end, the expansion profile curvature merges into a relatively sharp curvature of very small radius (i.e., of the order of 1% of the first and larger radius) that fairs smoothly into the lower face of the fastener head. Fatigue failures and corrosion problems in the fastener hole wall material starting at the hole entrance, and in some instances problems with warpage of a structural member caused by fastener installation are substantially avoided by the improved fastener.
For fatigue resistant structural joints, an interference fit, relatively nondeformable metal, headed, round pin-type fastener cooperable with structural members of relatively deformable metal to be fastened having a round straight fastener receiving hole therein, said fastener comprising an elongated round shank terminating at one end in a fastener head having an underside surface, said shank comprising a main body portion of straight cylindrical configuration larger in diameter than said hole and that terminates at its end opposite the head through a convexly rounded lead-in shoulder and, beyond such shoulder, in a protruding locking end portion of smaller diameter than said main body portion, said shank main body portion undergoing progressive expansion of diameter from said straight cylindrical configuration through a concave substantially curvilinear profile lengthwise thereof toward the fastener head with a relatively large starting radius of curvature tangential to said cylindrical configuration and continuing therefrom through a final concave curvature of relatively small radius fairing smoothly therewith and with the underside surface of the fastener head.
The method of manufacturing fatigue-resistant structural joints with interference fit fasteners joining together structural members of relatively deformable metal by fasteners of relatively nondeformable metal, headed, round pin configuration, said method comprising:
Dependencies are inferred from the claim text.