Fastening element (100) for a porous material, in particular for balsa wood, comprising a fastening head (1) configured to receive a torque in both rotational directions around a main axis (10) and a shank (2) that extends from the fastening head (1) and ends in a tip (3) at the end facing away from the fastening head. The shank (2) has an outer thread (4) along at least a section of its extension in a direction of the main axis (10), for screwing the fastening element (100) into the material.

In order to prevent wood fringes at the edge of a hole from a countersunk screw (1), the screw-head (2) is provided with a tapering underside and inclined milling-ribs (8) on the tapering underside. Each milling-rib (8) has a planar front-side (15) delimited by smoothly curved convex milling-edge (17) for milling the material during countersinking of the screw-head (2).

The present invention provides a fast chip removal reaming screw, including a screw head, a rod body extending from the screw head and a first thread arranged on the rod body. The rod body includes a rod body portion connected to the screw head, an reaming portion, and a pointed cone portion. The reaming portion includes first reaming blocks, second reaming blocks and third reaming blocks which are disposed in a helically staggered manner, and chip removal paths formed between the first reaming blocks, the second reaming blocks and the third reaming blocks. A first width of the chip removal path located between the first reaming blocks and a second width of the chip removal path located between the second reaming blocks are different, so that wood chips can be fast removed to reduce a stress between the screw and a wood workpiece.

A self-drilling screw structure comprises a screw head and a screw rod extending outwardly from the screw head. The screw rod is formed with a drill bit section at one end opposite to the screw head, a drill tail section and a screw thread section. The drill bit section comprises two first cutting edges extending helically and intersecting at a chisel edge. Two first chip flutes located at the positions respectively between the two first cutting edges and extending from the chisel edge toward the drill tail section. The drill tail section comprises two second cutting edges extending helically toward the screw thread section. Two second chip flutes located at the positions respectively between the two second cutting edges and extending helically toward the screw thread section. Each first chip flute and the second chip flute form a connection at joint between the drill bit and drill tail sections.

A screw includes a shank where a thread helix receiving groove winds around the shank and is disposed in the shank. A thread helix is disposed in the thread helix receiving groove where the thread helix has an expandable helix section. The shank has, at the thread helix receiving groove, a wedge flank for radially expanding the expandable helix section as the shank is moved relative to the expandable helix section. The expandable helix section has a helical back and a plurality of expansion fingers projecting axially from the helical back towards the wedge flank. The wedge flank of the thread helix receiving groove is configured for radially displacing the plurality of expansion fingers outwardly as the shank is moved relative to the plurality of expansion fingers.

A thread rolling screw molten through friction which is involved in metal plate installation field is publicized in the invention, and it is used to solve the problem that the method for breaking through the tradition is not formed for current connecting thread of metal plate structure to realize the simple and rapid efficiency improvement. The top of locating tip of the stated cone is connected with the expanding cone in a fixed way. The top of the stated expanding cone is connected with the pored shaping section in a fixed way. The top of the stated pored shaping section is connected with the transition section in a fixed way. The top of the stated transition section is connected with the self-tapping thread section in a fixed way. The external surface of the stated self-tapping thread section is set with tapered thread. The top of the stated self-tapping thread section is connected with the cylindrical locking thread section in a fixed way. The external surface of the stated cylindrical locking thread section is set with external thread. The top of the stated cylindrical locking thread section is connected with the transition fillet in a fixed way. The top of the stated transition fillet is connected with the concave storage ring in a fixed way. The top of the stated concave storage ring is connected with the flange in a fixed way.

A wood screw is disclosed herein. It comprises a screw head and a rod body integrally extended from the screw head and having a shank part and a screwing part, wherein the screwing part comprises a straight surface surrounded with a threaded section and a cutting section on which a cutting unit is formed, and wherein a root diameter of the shank part is larger than root diameters of the threaded section and the cutting section respectively, and larger than or equal to a maximum outer diameter of the cutting section defined by the cutting unit.

A wood screw is disclosed herein. It comprises a screw head and a rod body integrally extended from the screw head and having a shank part and a screwing part, wherein the screwing part comprises a straight surface surrounded with a threaded section and a cutting section on which a cutting unit is formed, and wherein a root diameter of the shank part is larger than root diameters of the threaded section and the cutting section respectively, and larger than or equal to a maximum outer diameter of the cutting section defined by the cutting unit.

A screw, especially for wood, has a knurled region (10) with two sets (11A, 11B) of ribs (11) that are offset from each other by an azimuth angle. For example, the two sets of ribs extend towards each other from opposite ends (10A, 10B) of the knurled region (10) and are intertwined only in an overlap region (12) that is at the middle of the knurled region.

A facade panel screw for the optimized fastening of facade panel elements on a substructure has a head with very large diameter D.sub.K, a substantially cylinder cross-sectional shaft, which is at least partially provided with a thread (nominal diameter D.sub.S) and a conical tip comprising a tip angle γ. The thread extends continuously from the shaft to the tip. It is characterizing that the tip angle γ is 45°+/−10°, the thread is embodied at least in a two-threaded manner, the head diameter D.sub.K is embodied at least twice as large as the nominal diameter D.sub.S; and the facade panel screw does not have a drill tip. Such a facade panel screw is used in a fastening arrangement, which comprises a load-bearing component (substructure) and a facade panel. Due to its design, the facade panel screw is able to simplify the fastening of the facade panel and to at least partially correct an inclined positioning in response to the installation.