Patent ID: 7670093
Filing Date: 2010-03-02
Classification: F16B

Abstract:
1. A fastener having a non-prismatic shank with an overall length L, the fastener intended for fastening elastic/plastic materials together and forming a joint for resisting lateral loads, the shank comprising; a section extent of said shaft being located in the midsection of said length and having generally straight, longitudinally extending ridges and grooves providing a variation in strength of cross section along the length of the shank, the ridges and grooves arranged symmetrically about the circumference of the shaft, the section extent including the shaft's maximum diameter D defined between the tips of oppositely-arranged ridges, the perimeter of a circle having diameter D inscribing the ridge's tips where the diameter D is in proportion to the length L and conforms to the following expressions: D is greater than or equal to 0.059 times L, and is less than 0.074 times L; the maximum diameter is arranged along the midsection of the shank in such manner as to be locatable at a joint in fastened materials in its intended use, the diameter between opposite grooves defining a core diameter that is approximately 0.59 times D and which defines the central core of the shaft, the area of the central core comprising at least 44 percent of the shank total shank cross-sectional area, and wherein the cross-sectional shape of the section extent as defined by the ridges and grooves has a moment of inertia about any axis through its center that is equal at each 45 degrees rotation of the axis, the length of the section extent being equal to or greater than 55% of the shank length L, the width of the each ridge tip having a length that is not less than about 0.12 times D and not greater than about 0.3 times D, each ridge being wider at its base than at its tip, the base width being of the order 0.44 times D thereby allowing the grooves to have sufficiently wide angular opening for material displaced by the shank to elastically compress and contact the shank by entering the grooves.