Patent ID: 7736110

Claim:
A staple for attaching together first and second metal sheets comprising: a length of round wire having a diameter in the range of 0.25 mm. to 2.0 mm., said wire being bent at the ends to form spaced apart depending metal legs; each of the legs having a metal piercing point at the end thereof adapted to pierce completely through the first sheet and at least partially through the second sheet and also adapted to spread the legs further apart during the piercing to a spread position in which the legs are anchored within the metal sheets and thereby attach the metal sheets together, said metal piercing points each having an outside bevel surface on the outside of the leg, an inside bevel surface on the inside of the leg, and a blunt end surface between the inside and outside bevel surfaces, and wherein; the inside bevel surface has an angle in the range of 45 degrees to 75 degrees from the blunt end surface, the outside bevel surface has an angle in the range of 60 degrees to 90 degrees from the blunt end surface, a chord formed at the intersection of the blunt end surface with the inside bevel surface is at a distance from the inside surface of the leg in the range of 0.15 to 0.5 of the diameter of the wire, and a chord formed at the intersection of the blunt end surface and the outside bevel surface is at a distance from the outside surface of the leg in the range of 0.15 to 0.4 of the diameter of the wire.