Patent ID: 8118527

Claim:
In a fastener which can be installed into at least one workpiece for combination with the at least one workpiece, the at least one workpiece having a first side, a second side, and a hole extending through the at least one workpiece from the first side to the second side, the improvement in the fastener comprising: an enlarged protruding head positioned at a proximal end of the fastener and substantially centered about a longitudinal axis; a substantially cylindrical smooth shank portion positioned adjacent and distal to the head and substantially centered about the longitudinal axis, the smooth shank portion having a first diameter providing an interference fit with the hole extending through the at least one workpiece; a threaded shank portion positioned distal to the smooth shank portion and substantially centered about the longitudinal axis, the threaded shank portion including a standard male thread configured to receive a female threaded nut, said fastener being heat treated such that said male thread is sufficiently strong to have a swage collar of a softer material swaged onto it without appreciable damage to the male thread, the male thread having a second diameter smaller than the first diameter of the smooth shank portion; a pin tail portion positioned distal to the threaded shank portion and substantially centered about the longitudinal axis, the pin tail portion including a plurality of circumferentially extending annular grooves and having a third diameter which is smaller than the second diameter of the threaded shank portion; a breakneck groove having a fourth diameter which is smaller than the third diameter of the pin tail portion, the breakneck groove being positioned between the threaded shank portion and the pin tail portion and immediately adjacent to and directly connected to said plurality of circumferentially extending annular grooves, and substantially centered about the longitudinal axis, the breakneck groove having a proximally tapered surface which tapers proximally from the pin tail portion toward the longitudinal axis of the fastener and a distally conically tapered surface which tapers distally from the threaded shank portion toward the longitudinal axis of the fastener, the breakneck groove being formed of a fastener material having a tensile strength controlled to ensure that the tensile strength of the breakneck groove is lower than any other portion of the fastener and that the fastener will sever at the breakneck groove when a preset range of tension is applied to the fastener at the pin tail portion; and an unthreaded swage collar providing a clearance fit between the swage collar and the pin tail portion, breakneck groove portion, and the threaded shank portion and configured to be swaged onto the threaded shank portion, and wherein said swage collar fits over the pin tail portion, breakneck groove portion, and the threaded shank portion without any interference.