Drive system with full surface drive contact
A drive system with full surface drive contact. The drive system tends to maximize the surface contact pattern or area at typical bit-recess reaction (drive) torque values, thereby tending to minimize bit-recess surface contact stresses, coating damage, recess ream and premature bit fatigue failure.
1. A fastener comprising a recess having a center; a drive surface in the recess, said drive surface extending from an inner to an outer diameter formed of polygon involutes comprising a plurality of continuous tangent arcs, wherein each arc has a radius within the recess wherein the arcs are concave relative to the center of the recess, where each radius is constant but different, and wherein each radius has a center located on locus points of a radius at the center of the recess.
2. A fastener as recited in claim 1 , wherein the recess is configured to provide a plurality of lobes, said lobes comprising drive surfaces which are formed of said polygon involutes.
3. A fastener as recited in claim 1 , wherein the recess is configured to provide a plurality of lobes, said lobes comprising drive surfaces which are formed of said polygon involutes.
4. A fastener as recited in claim 3 , wherein each arc is a segment of a circle.
5. A fastener as recited in claim 3 , further comprising a wall between each lobe, said wall being flat.
6. A fastener as recited in claim 3 , further comprising a wall between each lobe, said wall being concave circular.
7. A fastener as recited in claim 3 , further comprising a wall between each lobe, said wall being a convex vertex.
8. A fastener as recited in claim 3 , further comprising a wall between each lobe, said wall being a concave vertex.