Lock spindle blind fastener for single action application

Claim 1

In combination, an inner part having an opening provided therein, an outer part having a conventional countersunk opening provided therein and positioned in aligned relationship with said inner part opening, a pull type blind fastening for use in connecting said inner and outer parts, said fastening comprising a tubular sleeve and a mandrel positioned for longitudinal movement therein to form a blind head on the sleeve, said sleeve having a countersunk head in which the under surface has an included angle greater than the included angle of the countersunk opening, said head having an entrant straight wall counterbore terminating in an inwardly directed entry resistance angle less than the included angle of said countersunk head, said mandrel having an annular lock pocket, and an annular lock collar positioned to embrace said mandrel within said straight wall counterbore and adapted to be moved into said lock pocket along said entry angle while said under surface of said countersunk head is moved against said countersunk opening and said straight wall counterbore is deflected by said movement of said countersunk head against said countersunk opening to form a back taper over the end of the lock collar when the fastener is set.