Self tapping screw
AssigneeEJOT Verbindungstechnik GmbH & Co. KG
InventorsHerman Grossberndt, Gottfried König
Life of this patent
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Abstract
A cold-rolled screw which is intended for screwing into plastic has a narrow self-tapping thread with an inflection on at least one side of the thread so that the inner flank angle is smaller than the outer flank angle but still approximately equal to or larger than one third of the outer flank angle. In a second aspect, the screw thread has an end surface spaced from the free end of the screw to guide the plastic displaced by the thread during threading of the screw.
Claims9
Cold-rolled screw which has a head and a shank having an exterior surface with a thread and an end opposite the head with a guide for screwing the screw into a bore, wherein the guide includes a free end of the thread that is formed by an end surface which truncates the thread at the thread end, faces in the screw-in direction, and is directed obliquely with respect to a longitudinal axis of the screw so as to face generally away from the head, wherein the end surface is substantially flat and defined in part by a cutting edge that is an extension of a vertex of the thread and a base line which extends along the exterior surface of the shank between the cutting edge and a thread-base edge defined between one thread flank and the exterior surface of the shank, and wherein an extension of the base line away from the head runs at an angle relative to the thread-base edge which is substantially less than 90°.
Dependencies are inferred from the claim text.