Fatigue-resistant flared fastener
AssigneeDeutsch Fastener Corp.
InventorRahmatollah F. Toosky
Life of this patent
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Abstract
The fastener includes a nut, a basket, and a sleeve, the latter being received in an opening in a workpiece with its outer end flared to form an attaching flange. Spaced rounded lobes on the sleeve extend the full length of the opening and become embedded in the wall of the opening. The sleeve includes a corner surface adjacent its head which compresses and deforms the workpiece at one corner of the opening. A tool having an annular bulge is forced into the sleeve to expand it against the wall of the opening. When the end of the sleeve is flared to form the attacking flange, the other corner of the opening in the workpiece is compressed and cold-worked. The forces exerted by the sleeve on the workpiece greatly increase the fatigue life of the workpiece.
Claims21
The method of attaching a fastener to a workpiece so that said fastener will not rotate relative to the workpiece and the workpiece will have enhanced fatigue resistance comprising the steps of
- providing a fastener element adapted to mesh with a mating fastener element,
- providing a connection between said fastener element and a sleeve,
- providing said sleeve with a head at one end thereof, a tubular part spaced from said head, and a connecting part having an exterior surface projecting axially from said head and inclined radially inwardly to said tubular part,
- forming lobes on said tubular part extending axially thereof,
- providing a workpiece with a cylindrical opening shorter than the length of said tubular part with a diameter less than the diameter of said tubular part at the crests of said lobes and having a corner at either end,
- forcing said tubular part into said opening so that said lobes become embedded in the wall of said opening, thereby compressing and cold-working the same, so that said exterior surface of said connecting part reacts against one of said corners of said workpiece so as to deflect said one corner radially outwardly and axially inwardly of said opening thereby to compress and cold-work said workpiece at said one corner, and so that the outer end of said tubular part projects beyond the other of said corners,
- expanding said tubular part after said tubular part has been so forced into said opening so that at least a substantial portion of the exterior surface thereof is forced against the wall of said opening and compresses said workpiece along said opening,
- bending said outer end of said tubular part outwardly to form a flange overlapping said workpiece for axially retaining said sleeve to said workpiece, and forcing said tubular part in the vicinity of the base of said flange against the other of said corners of said workpiece so as to deflect said other corner radially outwardly and axially inwardly of said opening thereby to compress and cold-work said workpiece at said other corner.
In combination with a workpiece having parallel principal surfaces and a cylindrical opening interconnecting said surfaces, the wall of said opening intersecting one of said surfaces and being perpendicular to said one surface at said intersection so as to define a corner therebetween, a fastener for imparting fatigue resistance to said workpiece comprising
- a nut,
- a basket retaining said nut,
- said basket having opposed side walls and a bottom wall interconnecting said side walls and having an opening therethrough, said bottom wall being adapted to overlie said one surface with said opening through said bottom wall aligned with said opening in said workpiece, and
- a sleeve having a head overlying said bottom wall of said basket and a tubular portion extending from said head,
- said tubular portion having
- a first part of a first relatively large exterior diameter extending through said opening in said bottom wall of said basket and terminating substantially at the undersurface of said bottom wall,
- a second part of a second relatively small exterior diameter spaced longitudinally of said sleeve from said first part and adapted to enter said opening in said workpiece with the outer end of said sleeve projecting beyond the other of said principal surfaces of said workpiece,
- said outer end of said sleeve being bendable outwardly for forming a flange for retaining said fastener to said workpiece,
- and a third part projecting from said first part and inclined inwardly toward the longitudinal axis of said sleeve and toward the outer end thereof so as to interconnect said first and second parts for engagement with said corner of said workpiece for deflecting said corner radially outwardly and axially inwardly of said opening in said workpiece, thereby compressing and cold-working the material of said workpiece at said corner so as to increase the fatigue life of said workpiece,
- said second part of said sleeve having a plurality of rounded lobes thereon extending longitudinally thereof from at least the juncture of said second and third parts to at least said bendable outer end of said second part for engaging and compressing the material of a workpiece when said second part is received in an opening therein for increasing the fatigue life of said workpiece and preventing rotation of said sleeve relative to said workpiece, the exterior lateral dimension of said second part across the crests of said lobes being less than said first diameter.
In combination with a workpiece having an opening therethrough, a first surface at one end of said opening, a second surface at the opposite end of said opening, a first corner at the intersection of the wall of said opening and said first surface, and a second corner at the intersection of the wall of said opening and said second surface, a fastener for imparting fatigue resistance to said workpiece comprising
- a nut,
- a basket retaining said nut,
- said basket having opposed side walls and a bottom wall interconnecting said side walls and having an opening therethrough, said bottom wall overlying said first surface with said opening through said bottom wall being aligned with said opening in said workpiece, and
- a sleeve having a head overlying said bottom wall of said basket and a tubular portion extending from said head,
- said tubular portion having
- a first part of a first relatively large exterior diameter extending through said opening in said bottom wall of said basket and terminating substantially at the undersurface of said bottom wall,
- a second part of a second relatively small exterior diameter spaced longitudinally of said sleeve from said first part and received in said opening in said workpiece with the outer end of said sleeve extending beyond said opening and being bent outwardly to form a flange overlying said second surface for retaining said fastener to said workpiece, said sleeve at the base of said flange being deflected outwardly against said second corner and deflecting and compressing said workpiece radially outwardly and axially inwardly of said opening at said second corner, and
- a third part projecting from said first part and inclined inwardly toward the longitudinal axis of said sleeve and toward the outer end thereof so as to interconnect said first and second parts, said third part engaging said first corner and deflecting and compressing said workpiece radially outwardly and axially inwardly of said opening at said first corner,
- said second part having a plurality of rounded lobes thereon extending longitudinally thereof and embedded in the wall of said opening for preventing rotation of said sleeve relative to said workpiece, the exterior lateral dimension of said second part across the crests of said lobes being less than said first diameter,
- said tubular portion of said sleeve being expanded outwardly between said flange and said third part for compressing said workpiece at said opening, whereby the fatigue life of said workpiece is increased by said compression thereof at said first and second corners and along said opening.
Dependencies are inferred from the claim text.