Abstract: A fastener for securely fastening a plurality of members having a sleeve with a generally tubular portion and a flange extending radially from one end of the tubular portion and having a mandrel with an enlarged head and a generally cylindrical stem, the stem having a grooved locking section in which the locking groove has a longitudinal component and an adjacent tapered section containing a breakneck groove, the tapered section tapering radially outward toward the mandrel head and ending in a shoulder having an outer diameter signal to or greater than that of the locking section to provide a surface for improved retention of the mandrel with respect to the sleeve when the fastener is installed.

Abstract: A blind fastener for securely and economically fastening a plurality of members having a mandrel with an enlarged head and a generally cylindrical stem with a locking groove, and a sleeve with a generally tubular portion surrounding a portion of the stem, a flange extending radially from the end of the tubular portion opposite the stem head, and a boss extending axially from the flange opposite the tubular portion, so that application of tension to the stem and compression to the boss causes upsetting of the fastener, compression of the members, elongation of the stem, and displacement of the boss material into the locking groove, thereby locking the mandrel and sleeve to prevent them from springing back upon breaking of the mandrel stem.

Abstract: A blind fastener of the type wherein a cylindrical stem or mandrel pulled within a tubular sleeve or rivet body to cause legs formed in the latter to collapse outwardly into engagement with the blind side of a work piece. Such legs are formed in the rivet body by providing longitudinal cuts or slots, and each of such legs is deformed or crimped inwardly to provide an offset condition which virtually insures proper and effective outwardly collapsing of all of the legs, substantially simultaneously. The stem is further provided with a portion for engaging such legs at their respective offset locations to insure hole-filling and strong, firm setting of the collapsed legs against the work piece.