Blind fastener and blind fastener system

Claim 1

A blind fastener system comprising: a. at least two sheets in overlapping, abutting and compressive relationship with each other at their faying surfaces, the sheets having a driving side, a blind side and a hole extending through the sheets, the hole having a taper extending from the driving side to at least the abutting faying surfaces of the sheets, the taper of the hole converging towards the blind side, the sheets being substantially completely planar at least at the tapered hole; b. a nut having a conical nose at one end, a head at the other end, an intermediate portion between the two ends and an internally threaded axial bore, the intermediate portion being longitudinally tapered throughout its length with the taper converging towards the conical nose, the nut being within the hole in the sheets with the nose extending beyond the blind side, the head on the driving side and the intermediate portion in interference engagement with the wall of the tapered hole at least at the area thereof at the abutting faying surfaces of the sheets, the head and the tapered intermediate portion exerting an axial compressive force on the sheets on the driving side and on the wall of the tapered hole, respectively; c. a core bolt having a head and a threaded shank portion, the head extending outwardly from the conical nose and the threaded shank portion being threaded in the axial bore of the nut; d. a sleeve having a first end, a second end and an internal bore, the first end being in compressive engagement only with the blind side of the sheets, the second end being in compressive engagement with the head of the core bolt and the internal bore receiving the conical nose with the sleeve exerting a direct compressive force on the conical nose only exteriorally of said sheet; and e. the compressive relationship of the sheets being defined by the compressive force of the head and the tapered intermediate portion on the sheets acting towards the blind side, and the compressive engagement of the first end of the sleeve on the blind side acting towards the driving side; f. said parts of said system when in set position not being cold worked, due to the interference engagement being within the elastic limits of said parts, said sheets having no permanent deformation.