Swg Schraubenwerk Gaisbach Gmbh

Wuerth International Ag Part Interest

Swg Schraubenwerk Gaisbach Gmbh Part Interest

Guenter Stiebitz

Uwe Wolfarth

Patrick Roll

Joachim Glattbach

A drilling screw contains on its front end facing away from the screw head a drill bit having two drilling cutters. At an axial distance from the drilling cutters the screw shank has a constriction, within which the diameter of the screw shank is smaller than the diameter of the hole produced by the drill bit. The constriction is configured such that it has a shoulder running almost transversely to the longitudinal axis and facing the screw head and from which the diameter gradually approaches again the core diameter of the shank. Within this constriction begins the thread, wherein the thread edge initially has a distance from the longitudinal axis of the screw which corresponds roughly to the radius of the hole. The thread edge then runs along a spiral up to the final outer diameter of the thread on the shank.

Drilling screw

A design for a rotary drive both for a tool and for a workpiece to be rotationally driven is proposed. This rotary drive design contains a cylindrical basic shape which deviates from a circular cylindrical shape. The contour or the cross section through this basic shape has a plurality of rounded projections and rounded recesses arranged between said projections. The projections tangentially touch a circle having a maximum radius, while the recesses, for their part, tangentially touch a circle having a minimum radius. Deviating from this cylindrical basic shape, in the regions between the projections are configured conical surfaces, which are not instrumental in the transmission of torques, but take care of centering and alignment between the tool and the workpiece.

Rotary drive design

The invention concerns a screw, in particular a self-tapping screw, with a screw thread which reaches to the front end of the screw formed as a drilling tip. In the front area, starting with a distance from the front end of the screw, there is an opposite thread showing the same pitch as the screw thread, however, its thread height is lower than the thread height of the screw thread. This second, opposite single-thread, double-thread or triple-thread/multi-thread only reaches over the tapered drilling tip and leaves the shank of the screw free. It forms a cutting edge with its thread edge which is used to cut fibers in order to reduce wedge effect during screwing in the screw. The screw is particularly suitable for wood or wood-like materials in the edge areas of structural elements.

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Waldenburg, Germany

Guenter Stiebitz