Self-tapping or thread-forming screw

Claim 1

A METAL FASTENER HAVING A CONTINUOUS THREAD FOR THREADED ENGAGEMENT WITH A MATING THREAD IN A MEMBER TO BE SUPPORTED THEREBY AND A THREAD-FORMING PART FOR FORMING SAID MATING THREAD IN AN OPENING FORMED IN SAID MEMBER, COMPRISING A SCREW HAVING A SPIRALLY THREADED CYLINDRICAL SHANK WITH A HEAD AT ONE END AND A REDUCED TAPERED THREAD-FORMING PART AT THE OTHER END, THE METAL IN SAID THREAD-FORMING PART BEING COMPACTED TO TAPER AND REDUCE ITS CROSS SECTION AND PROVIDE A REDUCED SUBSTANTIALLY POLYGONAL END PORTION WITH UNIFORMLY SPACED AND COMPACTED RELIEF AREAS WIDENING TOWARD THE END OF THE REDUCED END PORTION, THE OTHER END OF THE THREAD-FORMING PART MERGING INTO THE ADJOINING CYLINDRICAL SHANK WITH THE LATTER HAVING A CONTINUOUS SPIRAL THREAD OF FULL THREAD DEPTH, SAID REDUCED TAPERED THREAD-FORMING PART HAVING UNIFORMLY SPACED CONVEX LANDS EXTENDING TO THE END OF THE SCREW BETWEEN SAID RELIEF AREAS, SAID RELIEF AREAS BEING GENERALLY FLAT ADJACENT THE END OF THE TAPERED PART AND HAVING TRANSVERSE END EDGES WHICH PROJECT AXIALLY BEYOND THE LANDS WITH MAXIMUM PROJECTION INTERMEDIATE THE ENDS OF SAID EDGES OF DEFINE A RECESSED SCREW END, SAID LANDS HAVING SPIRAL THREAD PORTIONS INTERRUPTED BY SAID SPACED RELIEF AREAS TO PROVIDE SPACED HELICES CONCENTRIC WITH THE AXIS OF THE SHANK AND EXTENDING OVER SAID LANDS WITH THE THREADED HELICES WHICH ADJOIN THE FULL THREAD OF THE CYLINDRICAL SHANK BEING CONTINUOUS EXCEPT FOR THEIR CRESTS BEING INTERRUPTED IN AXIAL ALIGNMENT WITH SAID RELIEF AREAS, SAID HELICES FROM SAID FULL THREAD PORTION AND TOWARD SAID END PORTION BEING PROVIDED WITH PROGRESSIVELY DISHED AND WIDENED RIDGES WITH SAID HELICES EXTENDING TO THE POLYGONAL END PORTION AND ALONG SAID LANDS WITH THE INTERRUPTED THREAD PORTIONS PROVIDED WITH LOBES HAVING BLUNT, NON-CUTTING LEADING SWAGING EDGES, GENERALLY CONVEX PORTIONS AND TRAILING EDGES WITH SAID LEADING AND TRAILING EDGES MERGING INTO SAID RELIEF AREAS, SAID RELIEF AREAS BEING SEPARATED BY THE GENERALLY CONCENTRIC HELICES WITH THEIR INTERRUPTED THREAD PORTIONS VARYING IN LENGTH AND CONTOUR IN SUCCESSIVE HELICES, THE THREADED LAND PORTIONS EXTENDING TO THE END OF THE THREAD-FORMING PART AND THE CONCENTRIC THREADED PORTION AT SAID END EXTENDING CIRCUMFERENTIALLY ABOUT THE CONVEX LAND PORTION, SAID HELICES BEING DEVOID OF CUTTING SURFACES TO PROGRESSIVELY SWAGE A THREAD BY PLASTIC DEFORMATION IN A MEMBER TO BE JOINED BY SAID SCREW.