Two-piece rivet

Claim 1

A two-piece rivet comprising: a shank member having an axis, and a head, a shank, and a thread in that order along the axis, said shank being cylindrical and having a shank, said thread being helical and having a substantially constant pitch, but having a major diameter which decreases as it extends away from a maximum adjacent to its end farthest from the shank, said maximum diameter being no greater than said shank diameter; and a ring-like collar to be swaged onto said thread, said collar having an inner wall and an outer wall, and a first and a second end, said inner wall defining a passage between said ends to receive with a substantial radial clearance at least a portion of said thread spaced from the end farthest from the shank, and with a larger diameter portion of the thread closer to said end and also received in said passage, whereby with said shank placed in an aperture in a workpiece, with at least a portion of the thread projecting beyond a surface of said workpiece, the collar may be placed over the thread, and with the shank restrained to prevent its being thrust back into the aperture, a swaging setting force having both axial and radial components can be exerted on the outer wall of the collar near its end farthest from the shank, whereby to force the other end of the collar against said surface of the workpiece, and to swage said inner wall adjacent to said first-mentioned end into the thread at its maximum diameter, and thereafter continuously moving said swaging force axially along the outer wall toward said surface to progressively and continuously swage the inner wall into engagement with the thread and maintain the axial force component against the workpiece thereby to exert through the thread a force on the shank member having an axial component directed away from said head.