Driven fastener having penetrating point for attaching objects to metal

Claim 1

A FASTENER COMPRISING A SHANK HAVING DRIVING AND DRIVEN END PORTIONS, SAID DRIVING END PORTION HAVING AN EXTERNAL TAPER DECREASING IN SIZE TOWARD ITS DRIVING EXTREMITY, SAID SHANK HAVING AN AXIALLY EXTENDING CAVITY IN ITS DRIVING EXTREMITY EXTENDING INWARDLY SUFFICIENTLY TO ALLOW THE NECESSARY PENETRATION OF THE FASTENER INTO THE METAL INTO WHICH IT IS DRIVEN, THE PENETRATING EXTREMITY OF SAID FASTENER TERMINATING IN A BLUNT SUBSTANTIALLY FLAT END THE SURFACE OF WHICH IS TRANSVERSE TO THE WALL OF SAID CAVITY WITH THE JOINT BETWEEN SUCH BLUNT END SURFACE AND CAVITY WALL AND BETWEEN THE EXTERNAL TAPER AND BLUNT END EACH BECOMING CUTTING EDGES WHEN THE FASTENER IS DRIVEN INTO METAL, THE RELATION OF THE EXTERNAL TAPER AND THE WALL THICKNESS OF THE BLUNT END SURFACE OF THE DRIVING END OF THE SHANK OF SAID FASTENER BEING OF SUCH CHARACTER THAT THE ENDWISE APPLICATION OF IMPACT FORCE TO SAID SHANK WILL CAUSE PENETRATION OF THE METAL INTO WHICH THE FASTENER IS DRIVEN AND WILL CAUSE THE CUTTING END TO BE DIRECTED INWARDLY TOWARD THE AXIS OF THE SHANK IN A MANNER TO CAUSE CUTTING AS ITS TRAVELS WITH A GRADUALLY PROGRESSIVE CONTRACTUAL MOVEMENT AND WITH A BULBOUS MASS OF METAL COLLECTED AND RETAINED WITHIN SAID CAVITY WHILE MAINTAINING ITS CONNECTION WITH SAID METAL.