Blind fastener

Claim 1

IN A STRUCTURAL BLIND FASTENER FOR USE IN ATTACHING TOGETHER AT LEAST TWO MEMBERS A SIDE OF ONE OF WHICH IS INACCESSIBLE OR BLIND AND HAVING ALIGNED OPENINGS THEREIN OF SUBSTANTIALLY UNIFORM DIAMETER WITH THE POSSIBLE EXCEPTION OF THE ACCESSIBLE END WHICH MAY BE COUNTERBORED, A RELATIVELY NONDUCTIBLE SUBSTANTIALLY HOMOGENEOUS DISCRETE INTERNAL OR BLIND METAL PART COMPRISING A CYLINDRICAL SHANK PROVIDED WITH A THREAD, SAID BLIND PART INCLUDING A HEAD FORMED INTEGRAL WITH THE BLIND END OF SAID SHANK THE DIAMETER OF WHICH HEAD IS APPROXIMATELY 150% OF THE EFFECTIVE DIAMETER OF SAID SHANK, A PROJECTION FORMING A DRIVING CONNECTION ON THE NONBLIND END OF SAID SHANK CONNECTED THERETO BY A SECTION OF LESS STRENGTH THAN THE STRENGTH OF THE MINIMUM EFFECTIVE CROSS-SECTIONAL AREA OF SAID SHANK, A RELATIVELY DUCTILE BLIND HEAD PART IN THE FORM OF A CONTINUOUS CYLINDRICAL SLEEVE HAVING AN INTERNAL THREAD AT AT LEAST ONE END OF NOT LESS THAN TWO CONVOLUTIONS AND AT NO PLACE AN INSIDE DIAMETER SUBSTANTIALLY GREATER THAN THE MAXIMUM THREAD DIAMETER OF SAID THREAD ON SAID SHANK OF SAID BLIND PART AND AN OUTSIDE DIAMETER SUBSTANTIALLY EQUAL TO THE DIAMETER OF SAID HEAD OF SAID BLIND PART AND BEING THREADED ONTO SAID SHANK OF SAID BLIND PART WITH SAID ONE END ADJACENT TO SAID HEAD THEREOF, AND AN EXTERNAL OR NONBLIND METAL PART THREADED ONTO THE THREADED SECTION OF SAID SHANK OF SAID BLIND PART, SAID NONBLIND PART COMPRISING A CYLINDRICAL TUBULAR-LIKE BODY PORTION HAVING AN OUTSIDE DIAMETER SUBSTANTIALLY EQUAL TO THE DIAMETER OF SAID HEAD OF SAID BLIND PART, SAID BODY PORTION HAVING A HEAD FORMED INTEGRAL THEREWITH AT THE NONBLIND END THEREOF FOR ENGAGING THE ACCESSIBLE OR NONBLIND SIDE OF SAID MEMBERS AND AN AXIALLY EXTENDING FRUSTO-CONICALY SHAPED BEARING SURFACE ON ITS OTHER END INCLINED OUTWARDLY AND TOWARDS THE NONBLIND END OF SAID INTERNAL PART FOR EXPANDING THE END OF SAID BLIND HEAD PART ADJACENT THERETO BEYOND THE YIELD STRENGTH OF THE MATERIAL THEREOF BUT UNDER THE ULTIMATE STRENGTH THEREOF TO FORM A BLIND HEAD ENGAGING THE INACCESSIBLE SIDE OF SAID MEMBERS UPON SAID FRUSTO-CONICAL SURFACE BEING FORCED INTO SAID END OF SAID BLIND HEAD PART UPON ROTATION OF SAID BLIND PART RELATIVE TO SAID NONBLIND PART IN DRIVING SAID FASTENER WHEREBY SAID MEMBERS ARE SECURED TOGETHER BY BEING EMBRACED BETWEEN BLIND AND NONBLIND HEADS ENGAGING OPPOSITE SIDES THEREOF ONE OF WHICH HEADS IS RELATIVELY HARD BUT MORE DUCTILE THAN THE INTERNAL OR BLIND PART OF THE FASTENER.