Patent ID: 7255522
Filing Date: 2007-08-14
Classification: B21K,B25B,F16B,Y10S

Abstract:
1. A recess formed in the top surface of the head of a fastener, said recess comprising: multiple radially inward extending lobes that define spirally configured driving surfaces, said driving surfaces extending substantially axially, from outward facing top surfaces of the lobes towards the bottom of the recess, said driving surfaces constructed for engagement with a mating drive tool for rotating said fastener in installation and removal directions about a longitudinal axis, said recess further comprising: a substantially cylindrical, axially aligned, counterbore constructed in an upper surface of the fastener head wherein the outward facing top surfaces of said multiple lobes are recessed therein; a non-driving ramp surface constructed on each of said multiple lobes on the outward facing surfaces thereof, each of said ramp surfaces further comprising: an installation ramp portion extending radially inward and circumferentially in the installation direction from an apex of said ramp surface, wherein said installation ramp portion declines from the apex at a compound angle both radially and circumferentially; and a removal ramp portion extending radially inward and circumferentially in the removal direction from the apex of said ramp surface, wherein said removal ramp portion declines from the apex at a compound angle both radially and circumferentially; and further wherein said installation ramp portion and said removal ramp portion are adapted to urge a rotating drive tool into mating engagement with the drive surfaces in either the installation or removal directions.