Blind rivet assembly

Claim 1

A BLIND RIVET ASSEMBLY, COMPRISING: (A) A HOLLOW RIVET OF DUCTILE MATERIAL INCLUDING A TUBULAR BARREL WITH A HEAD AT ONE END, THE RIVET HAVING AN AXIAL BORE EXTENDING THROUGH THE HEAD AND BEING OF SUCH SIZE THAT THE BARREL MAY BE INSERTED INTO AN APERTURE IN A WORKPIECE WITH THE HEAD ABUTTING AN EXTERIOR SURFACE OF THE WORKPIECE SAID BORE HAVING AN ENLARGED SECTION TO PROVIDE A SHOULDER; (B) A CLINCHING MANDREL INCLUDING A SHAFT WITH AN ENLARGED PORTION AT ONE END, THE ENLARGED PORTION BEING RECEIVED WITHIN THE RIVET BARREL NEAR THE UNHEADED END AND ENGAGING SAID SHOULDER, AND THE SHAFT EXTENDING THROUGH THE BORE TO A POSITION BEYOND THE RIVET HEAD WHERE IT CAN BE GRIPPED AND PULLED AWAY FROM THE RIVET HEAD, TO COMPRESS THE BARREL AND FORCE IT TO BULB OUTWARD AND FORM A SECOND HEAD ON THE RIVET ABUTTING THE INTERIOR SURFACE OF THE WORKPIECE; AND (C) AN AXIALLY BORED PLUG SLIDABLY RECEIVED ON THE MANDREL SHAFT IN ENGAGEMENT WITH THE EXTERIOR SURFACE OF THE RIVET HEAD, THE EXTERIOR DIMENSIONS OF THE PLUG BEING SUCH THAT IT CAN BE FORCED INTO THE RIVET BORE FROM THE HEAD END AS THE MANDREL PULLED, THE PLUG HAVING AN OUTWARDLY TAPERED EXTERIOR PORTION WHICH FORCES THE MATERIAL OF THE RIVET TO EXPAND OUTWARD INTO SEALING ENGAGEMENT WITH THE WALLS OF THE APERTURE IN THE WORKPIECE AS THE PLUG IS FORCED INTO THE RIVET, THE EXPANSION CAUSED BY THE PLUG COOPERATING WITH THE BULBING CAUSED BY THE MANDREL TO FORM A TIGHT SEAL BETWEEN THE RIVET AND THE WORKPIECE.