Patent ID: 7896598

Claim:
A fastener, comprising: a pin member having an elongated pin shank adapted to be located in aligned openings in a plurality of workpieces, the pin member terminating at one end in a head that is adapted to engage a surface on one side of the workpieces and at its opposite end in a grooved portion that is adapted to extend past an opposite surface on an opposite side of the workpieces, the grooved portion including a locking portion having a plurality of lock grooves defined by circumferentially extending pin grooves and associated pin shoulders terminating in pin crests; and an as-headed collar including a generally straight collar shank that is adapted to be swaged into the lock grooves of the pin member in response to a swage load applied between the pin member and the as-headed collar, thereby providing a desired magnitude of clamp load on the workpieces, the as-headed collar, when swaged, having collar grooves and collar shoulders that interlock with the pin grooves and the pin shoulders, wherein the pin member and the as-headed collar include ultimate shear stresses of different magnitudes in order that yielding of the pin member is substantially avoided upon swaging the collar to the pin member, wherein the as-headed collar does not require thermal processing, and the collar shank of the as-headed collar has a wall thickness which is relatively thin, thereby reducing the swage load required to swage the as-headed collar, and wherein the as-headed collar has an outer diameter and an inner diameter, and wherein the ratio of the outer diameter to the inner diameter of the as-headed collar is between about 1.47 to 1.55.