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US 4,572,720 AGranted
Wood screw
AssigneeRockenfeller KG Befestigungselemente
InventorsGottfried Rockenfeller, Wolfgang Rockenfeller
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AssigneeRockenfeller KG Befestigungselemente
InventorsGottfried Rockenfeller, Wolfgang Rockenfeller
Estimating the term…
Disclosed is a wood screw with a head separated from a threaded extremity by an unthreaded shank whose diameter is less than the outer diameter and only slightly larger than the root diameter of the thread. A cylindrical or tapering neck inserted between the head and the shank has a diameter, at least in the immediate vicinity of the head, equaling the outer thread diameter. The threaded extremity terminates in a pyramidal tip with three or four sides, at least one edge of the pyramid being notched by an extension of the thread groove to act as a spur in cutting a bore ahead of the advancing screw thread. The turns of the thread, in one embodiment, have leading flanks merging into or overhung by rounded ridges enabling the screw to be hammered into a substrate of natural wood or particle-board composition.
A wood screw comprising a metallic rod with a threaded extremity having helical turns centered on an axis, an enlarged head at an end opposite said extremity, an unthreaded portion separating said head from said extremity, and a neck of lesser diameter than said head interposed between the latter and said unthreaded portion, said turns having an outer diameter exceeding that of said unthreaded portion and a root diameter slightly less than that of said unthreaded portion, said neck having a maximum diameter substantially equaling said outer diameter, said neck having an axial length substantially equaling the diameter of said unthreaded portion, said neck tapering frustoconically from said maximum diameter adjacent said head to a diameter equaling that of said unthreaded portion, said turns having a generally trapezoidal profile in axial section with a leading flank and a trailing flank converging radially outward while including acute angles with an intermediate line perpendicular to said axis, said leading flank terminating short of said intermediate line and adjoining a convex curve which traverses said intermediate line and meets an inwardly sloping back edge extending to said trailing flank.
A wood screw comprising a metallic rod with a head at one end and a threaded extremity remote from said head having helical turns centered on an axis, said extremity terminating in a pointed tip at an end opposite said head, said turns having a generally trapezoidal profile in axial section with a leading flank and a trailing flank converging radially outward while including acute angles with an intermediate line perpendicular to said axis, said leading flank terminating short of said intermediate line and adjoining a convex curve which traverses said intermediate line and meets an inwardly sloping back edge extending to said trailing flank, said leading and trailing flanks being rectilinear in cross section, said back edge being substantially orthogonal to said leading flank and includes an angle between substantially 10.degree. and 15.degree. with said axis.
Dependencies are inferred from the claim text.