Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Externally threaded fastener element – e.g. – bolt – screw – etc. – Head having counter-sinking means
Reexamination Certificate
2000-02-23
2001-09-18
Saether, Flemming (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Externally threaded fastener element, e.g., bolt, screw, etc.
Head having counter-sinking means
C411S188000, C411S387200
Reexamination Certificate
active
06290444
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The invention relates to a countersunk head screw with a head, with a shank, and with a thread extending at least partially over the shank, whereby the head, at least in sections, features a bearing surface that tapers conically toward the shank.
2. Discussion
Screws of this kind are known. For example, they may feature a drive groove, such as a slot or a cross recession for engaging the screwdriver. The open end of the shank can be shaped as a point. In particular, we can be dealing with countersunk head screws that have the effect of shaping or cutting a thread into the material into which they are screwed.
The head must be made appropriately voluminous so that there will be enough room available for the drive groove. For example, one known way to achieve this is to provide two different head sections for the bearing surface that tapers conically toward the shank. In these head sections, the bearing surface converges at different angles.
Since there is no thread on the head, a possible problem when screwing with a voluminous head is that undesired destruction of material can occur, especially on the surface, such as splintering, tearing, or deformation, depending on the material, once the screw has been completely or almost completely screwed in.
It is the objective of the invention, to improve a countersunk head screw of the type described in the introduction, so that the negative occurrences cited above can be prevented.
SUMMARY OF THE INVENTION
In accordance with the teachings of the present invention, a countersunk head screw is provided. The countersunk head screw includes a head connected or integrally formed with the shank. A thread extends at least partially over the shank and a section of the head includes a bearing surface that tapers conically toward the shank. At least one cutting rib is arranged in a lower region of the bearing surface that is facing or adjacent the shank. Additionally, at least one restraint rib is arranged in a top region of the bearing surface turned away or spaced apart from the shank.
The objective of the invention is achieved by arranging cutting ribs in a lower region of the bearing surface that is facing, or adjacent, the shank.
When a countersunk head screw in accordance with the invention is being screwed in, the cutting ribs will cause material to be removed, whereby an undesired destruction of material can be efficiently prevented, even for a countersunk head screw whose head is larger than that of standard screws.
REFERENCES:
patent: 1175665 (1916-03-01), Sweet
patent: 2037586 (1936-04-01), Olson
patent: 3903784 (1975-09-01), Dekker
patent: 4572720 (1986-02-01), Rockenfeller
patent: 5205694 (1993-04-01), Nagoshi
patent: 5249882 (1993-10-01), Nagoshi
patent: 5516248 (1996-05-01), DeHaitre
patent: 5683217 (1997-11-01), Walther
patent: 5772376 (1998-06-01), Koing
patent: 113183 (1918-02-01), None
A-Z Ausrustung und Zubehor GmbH & Co. KG
Harness Dickey & Pierce PLC
Saether Flemming
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