Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Having separate expander means – Comprising a head and expandable portions spread by fastener
Patent
1998-08-21
2000-12-12
Saether, Flemming
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Having separate expander means
Comprising a head and expandable portions spread by fastener
411 805, F16B 1306
Patent
active
061589349
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a knock-in pin dowel. Knock-in pin dowels are normally made from plastic and are prefabricated with an expandable element already inserted to some extent into the dowel shell. The fitting of an article to a substrate takes place very easily, because the dowel only has to be inserted through the object to be fixed and then, with the aid of a hammer, the fitter strikes the head of the expandable element. This blow serves both to completely introduce the dowel shell and to subsequently expand the dowel shell by the expandable element driven into it.
Normally the dowel shell contains an expandable part, which has two diametrically arranged longitudinal slits, so that two segments are formed, which can be folded outwards. The expandable element is generally a nail having a sawtooth-like thread, the latter not impeding the knocking in process (DE-OS 26 07 338, DE-OS 39 12 749).
This type of dowel is generally used when concrete constitutes the substrate and in which relatively good, cylindrical drilled holes can be produced.
However, there are increasing numbers of building materials, in which the material is more loosely seated, so that it is not possible to produce precise dowel holes, e.g. hollow chamber blocks or stones or lightweight building materials. Thus, the knock-in pin dowel is not adequately secured in such building materials.
The problem of the invention is to provide a knock-in pin dowel, which ensures a good anchoring, even in unfavourable wall building materials.
SUMMARY OF THE INVENTION
The invention relates to a knock-in pin dowel having two longitudinal slits located at different points on the dowel shell, wherein the expandable part of said shell is split up into two expandable areas, each of which can be expanded and can therefore engage on the dowel hole wall. Even if one expandable area cannot bring about an anchoring, because at said point there is a chamber of a hollow chamber block, the second expandable area can bring about anchoring. In irregularly shaped drilled holes, the two expandable areas can be expanded to a different degree. Thus, even if the building material is not particularly favorable, the dowel always leads to a good anchoring and in many cases also along a larger surface with a constant pressing force.
According to a further development of the invention, the at least one or also several longitudinal slits of the first expandable area is circumferentially displaced with respect to the at least one longitudinal slit of the second expandable area.
According to another further development of the invention, the longitudinal slits in the two expandable areas overlap in the longitudinal direction of the dowel shell. As a result the two expandable areas also overlap somewhat. In the other case, when the two expandable areas do not overlap, a central area can be formed, in which there is no expansion. In individual cases, this may also be desired. However, the overlapping of the expandable areas leads to the creation of an extended or lengthened expandable area, which in the case of good drilled holes leads to a clamping along a considerable length, whilst the advantages of two separate expandable areas are maintained in the case of poor material.
The invention provides at least two longitudinal slits in each expandable area. Admittedly, expansion occurs when there is only one longitudinal slit, but the expansion is more favorable with two slits.
As the expansion behaviour of the expandable area with the longitudinal slits closed on both sides is different than that of an expansion area at the end of the dowel, where the longitudinal slits continue through to the end and consequently, do not need to be closed, according to a further development of the invention, there are a different number of longitudinal slits in the two expandable areas.
It is also possible for the length of the two expandable areas to differ.
As the dowel shell is to be injection molded from plastic, for a simplified production of the dowel according
REFERENCES:
patent: 3199398 (1965-08-01), Weisz
patent: 3516324 (1970-06-01), Berner
patent: 4789285 (1988-12-01), Fischer
Adolf Wurth GmbH & Co. KG
Saether Flemming
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