The invention relates to a self-tapping screw.
This type of self-tapping screw is screwed into a predrilled drill hole in the substrate using a suitable tool such as, for example, a screwdriver, drill hammer, screw-wench or the like, wherein the start of the thread of the screw grooves a mating thread into the substrate that corresponds to the thread. The subsequent thread of the screw engages in the mating thread, whereby when a load is applied to the screw, it transmits the load to the substrate. In a soft substrate such as, for example, porous concrete or plasterboard, self-tapping screws can also be screwed in directly without predrilling a drill hole in the soft substrate.
An essential advantage of self-tapping screws is the possibility of unscrewing them from the substrate without parts of the fastening that was created remaining in the substrate. Self-tapping concrete screws, which are driven into mineral substrates, are also used in practice by users for temporary fastenings, for example, in concrete form work, building scaffolding or when configuring drilling and cutting tools in diamond drilling and separating technology. As a result, the self-tapping screws are not only removable, but are also reusable in principle.
Known from European Patent Document No. EP 1 862 677 A1 is a self-tapping screw with a shaft, which has a first end and an opposing second end with a load-engaging means, and with a thread, which extends at least in sections over the length of the shaft, wherein at least one wear indicator means is provided on the thread.
The at least one wear indicator means of the known screw indicates the rate of wear of the thread and thereby allows a conclusion to be drawn about the load capacity or load bearing property of a removed self-tapping screw and about its ability to be reused.
When manufacturing the screw as well as during its use, parts of the thread can break out, which the user might inadvertently interpret as wear indicator means. This could lead to a misinterpretation with respect to the reusability of the screw.
The object of the invention is creating a self-tapping screw, in particular a concrete screw, which can be used several times and in which a simple assessment of usability is possible.
According to the invention, at least one identifier is provided on the screw for identifying the wear indicator.
The at least one identifier guarantees a clear identification of the at least one wear indicator. Because of the identifier provided on the screw, it is no longer possible for any undesired breakouts in the thread or damage to the thread to be inadvertently interpreted as a wear indicator. As a result, even with repeated use of a self-tapping screw that has wear indicators, a reliable assessment by the user with respect to its reusability is guaranteed.
The at least one identifier is preferably provided on a thread flank of the thread and preferably directly adjacent to the wear indicator to be identified by this identifier. The at least one identifier is advantageously configured directly during the forming of the thread on the thread.
The at least one identifier is preferably provided on an outer side of the shaft and advantageously directly adjacent to the wear indicator to be identified by this identifier. The at least one identifier is advantageously configured directly during the forming of the shaft on the shaft.
Several identifiers may be provided on a self-tapping screw, each of which is arranged on the thread flanks of the thread and/or on the outer side of the shaft.
The at least one identifier is preferably a depression provided on the screw, which can be configured in a simple manner during manufacturing of the self-tapping screw, e.g., in a rolling method, on the screw.
The at least one identifier is preferably an elevation provided on the screw, which can be configured in a simple manner during manufacturing of the self-tapping screw, e.g., in a rolling method, on the screw.
Several identifiers may be provided on a self-tapping screw, which are configured as depressions and/or as elevations. In addition, the at least one identifier may also be a profiling, which features only depressions, only elevations, or depressions and elevations.
At least two identifiers are preferably provided for identifying a wear indicator, which make a simple and precise identification of the wear indicator possible.
The at least one identifier preferably has a polygonal design in plan view, whereby the at least one identifier features an advantageous design for identifying the corresponding wear indicator. A corner of the at least one identifier advantageously points in the direction of the to-be-identified wear indicator, thereby further improving the identifiability of the to-be-identified wear indicator. The identifier has an especially advantageous triangular design in plan view.
In an alternative embodiment, the at least one identifier has a round design in plan view, thereby making it possible for the at least one identifier to be configured in a simple way. In addition to a circular design, the at least one identifier may also have an oval design or a design with more than two inflection points.
The invention is explained in greater detail in the following on the basis of exemplary embodiments.