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US 5,234,301 AGranted
Hole forming and selftapping screw
AssigneeEJOT Eberhard Jaeger GmbH & Co. KG
InventorsHermann Grossberndt, Gunter Kretschmer, Horst Klees
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AssigneeEJOT Eberhard Jaeger GmbH & Co. KG
InventorsHermann Grossberndt, Gunter Kretschmer, Horst Klees
Estimating the term…
Hole forming and selftapping screw of up to approximately 6 mm thread diameter for tapping into sheet metal of a thickness of up to approximately 1 mm comprising a head including a formation for receiving a tool, a thread shank and a cylinder member following thereon having a diameter less than the thread-pitch diameter of the thread shank, merging into a tapered hole forming member. The thread shank merges with the cylinder member via a taper extending over approximately four threads, a distance corresponding approximately to the four-fold sheet metal thickness. The hole forming member terminates in a convexly curved friction surface corresponding to a radius (R) of approximately 0,5 mm. The entire screw is formed in one piece of tempered steel having a tensile strength of up to approximately 1400 N/mm.sup.2, mechanically hardened steel respectively.
A hole forming and self-tapping screw comprising a head including a formation for receiving a tool, a threaded shank, a cylinder portion adjacent thereto having a diameter less than the thread-pitch diameter of the threaded shank and a tapered hole forming portion merging into the cylinder portion, characterized in that the threaded shank merges with the cylinder portion via a taper extending over approximately four threads, that the hole forming portion has a cone-like configuration and includes a smooth non-cutting exterior surface defined by a plurality of successive zones, one of said zones being adjacent said cylinder portion and including a series of flattened portions defined along different sides of said screw separated by rounded non-cutting transition segments, one other of said zones terminating in a convexly curved friction surface without cutting edges corresponding to a radius of curvature of approximately 0.5 mm, and that the entire screw is formed as one piece, whereby said screw enables the formation and tapping of a hole in a metal sheet without the creation of chips.
A hole forming and self-tapping screw comprising:
A hole forming and self-tapping screw comprising:
Dependencies are inferred from the claim text.