WOOD SCREW WITH AROUND-SHAPED PROPOSE BETWEEN THREADS

Description

[0001] The invention relates to a screw, a method for inserting a wood screw into a wooden substrate, a method for manufacturing a wood screw and a use.

[0002] A screw is a bolt that may have a drive mechanism, and the bolt is externally threaded. In screws with a head, the annular surface under the head serves as a stop against the part being fastened.

[0003] When inserting a screw into wood, pre-drilling is sometimes omitted, allowing a wood screw to be driven directly into solid wood without pre-drilling. In this case, the screw thread cuts its own mating thread into the wood. A well-known example of a wood screw is the Assy Plus or Assy 3.0, sold by Würth. A measure of the strength of a wood screw's anchoring in wood is its pull-out value. This refers to the tensile force required to pull the screw out of the wood, thus overcoming the holding force of the screw in the wood.

[0004] Although the well-known wood screw of type Assy Plus or Assy 3.0 already shows very good pull-out values, a further improved pull-out strength of a wood screw would still be desirable.

[0005] The commercially available Spax 4CUT screw has a square shape at the transition from the thread to the shank. The advantage of this screw lies in the reduced driving torque. This allows the Spax 4CUT to be driven smoothly and with minimal effort. Furthermore, it also conserves the energy reserves of a battery-powered tool.

[0006] DE 102014205464 A1 discloses a screw comprising a thread extending from a screw drive end of a cylindrical screw shaft to a screw tip. The screw tip is located at the end of a front conical section of the screw. The screw includes four axially extending ribs that begin at the front end of the cylindrical screw shaft and extend almost to the screw tip. In the region of the screw drive end, the screw also includes four ribs that are arranged circumferentially offset from the front ribs by half the angular distance between each pair of ribs.

[0007] EP 1411252 A2 discloses a screw with a shaft which is formed at one of its two ends with an actuating head and at the other of its two ends with a conical tip, and which is formed with a screw thread at the conical tip and in the area adjoining it. In the area of ​​the shaft adjacent to the conical tip, between the threads, ribs extending transversely to the direction of rotation of the screw are formed by which the material is compacted by displacement when the screw is tightened.

[0008] EP 2665941 A1 discloses a chipboard screw with a screw head, a screw shank, a screw tip, a thread extending over at least a part of the screw shank and / or the screw tip, and with several scraper ribs extending in the longitudinal direction of the screw, which have a triangular cross-section with a flattened tip.

[0009] Milling cutters can be attached to the tip of a screw. These cutters run parallel to the screw axis and have a constant square or triangular cross-section. They reduce the screw's insertion torque when driven into wood. However, the action of the milling cutters also reduces the screw's holding power in the wood, as the wood between the load-bearing threads is milled away or physically damaged when the screw is installed. The taller the radial diameter of the milling cutter, the greater the reduction in pull-out forces.

[0010] US 6,739,815 B2 discloses a wood screw comprising: a shank; a screw tip; threads extending circumferentially on at least a portion of the shank into the screw tip; at least one arcuate projection between at least two adjacent threads, wherein a principal direction of the projection in a top view of the wood screw is tilted counterclockwise by an angle of 120° (corresponding to 60° clockwise) relative to an axial direction of the wood screw.

[0011] EP 0 939 235 A1 discloses a wood screw comprising: a shank; a screw tip; threads extending circumferentially on at least a portion of the shank into the screw tip; a first group with at least one arcuate projection between two adjacent threads and a second group with at least one arcuate projection between two other adjacent threads, wherein a principal direction of each projection is tilted counterclockwise by an angle of between 5° and 20° relative to an axial direction of the wood screw in a top view. The projections of the two groups are aligned with each other. WO 2016 / 180661 A1 discloses a further prior art wood screw.

[0012] The object of the present invention is to create a wood screw with which splitting forces can be reduced and yet high pull-out forces can be achieved.

[0013] This problem is solved by the objects having the features according to independent claims 1, 13, 14 and 15. Further embodiments are shown in the dependent claims.

[0014] According to one aspect of the present invention, according to claim 1, a wood screw is provided comprising a shank, a screw tip, threads extending circumferentially on at least a portion of the shank (in particular extending into the screw tip), a first group with at least one arcuate projection between two adjacent threads, and a second group with at least one arcuate projection between two other adjacent threads. A principal direction of each projection, viewed from a top view of the wood screw, is tilted counterclockwise by an angle between 5° and 40° relative to an axial direction of the wood screw, and all projections are arranged such that they are not aligned with one another.

[0015] According to another aspect of the present invention, according to claim 13, a method for inserting a wood screw with the features described above into a wooden substrate (in particular into a solid wood substrate) is provided, wherein in the method the wooden substrate (in particular without pre-drilling a borehole in the wooden substrate into which the wood screw is subsequently inserted) is provided, and the wood screw (in particular without pre-drilling and / or self-tapping or thread-cutting) is screwed into the wooden substrate.

[0016] According to yet another aspect of the present invention, according to claim 14, a method for producing a wood screw is provided, wherein in the method a shank and a screw tip axially adjoining it (in particular directly, i.e. without any further structure arranged in between, or indirectly, i.e. with at least one further structure arranged in between) are formed, threads are formed which extend circumferentially on at least a part of the shank (in particular up to the screw tip), and a first group with at least one arcuate projection between at least two adjacent threads and a second group with at least one arcuate projection between two other adjacent threads is formed on the shank and / or on the screw tip.A main direction of the respective projection in a top view of the wood screw is tilted counterclockwise by an angle between 5° and 40° relative to an axial direction of the wood screw, and all projections are arranged so that they are not aligned with each other.

[0017] According to a further aspect of the present invention, according to claim 15, a wood screw with the features described above is used for insertion into a wooden substrate, in particular without pre-drilling.

[0018] Within the scope of the present application, the term "arc-shaped projection" can be understood to mean a radially projecting elevation or bulge extending from the shank or screw tip, which has the shape of one or more arcs, at least in sections. Such an arc-shaped projection can, in particular, be designed as an axially convex body. Such a convex body can extend outward from the shank, then expand axially to a maximum radial thickness, and then continue to extend axially back into the shank. In one embodiment, the arc-shaped projection can consist of exactly one curved arc. In another embodiment, the arc-shaped projection can be arc-shaped only in sections and can also have one or more further sections, for example, one or more further arcs.Such an arc shape can be formed by a continuous or continuous curvature of the projection between two ends, with an intermediate local maximum. However, steps or gradations in the form of edges on the arc-shaped projection are also possible. The arc shape can be axial to the wood screw. Alternatively or additionally, the arc shape can also be tangential to the wood screw or its shank. If a projection exhibits arc-shaped components in both the axial and tangential directions, the axial extent of the arc-shaped projection can be longer than its tangential extent.

[0019] Within the scope of this application, the term "shank" or "bolt" can be understood to mean, in particular, an axially and radially central section of the wood screw, which is arranged in the axial direction between a screw tip and another end of the wood screw opposite the screw tip. Such a shank can, for example, be a circular cylindrical body on which threads are formed and project radially. One or more arcuate projections can also be formed, at least partially, on the shank. Optionally, a threadless section can be attached to an end of the shank opposite the screw tip, a screw head can be attached directly or indirectly, or the wood screw, then formed like a bolt, can end without a radially flared screw head.

[0020] Within the scope of this application, "threads" can be understood to mean, in particular, a helically encircling elevation around the shank or screw tip, which facilitates the driving of the wood screw into a substrate and can increase the pull-out forces. Such a thread, formed by the threads, can in particular be designed as a self-tapping or self-tapping thread. More preferably, the threads themselves can form a self-tapping or self-tapping mating thread in the substrate even when the wood screw is inserted without pre-drilling.

[0021] Within the scope of this application, the term "screw tip" can be understood to mean, in particular, an axial end section of the wood screw, which may be radially tapered compared to the shank. When the wood screw is inserted into a substrate as intended, this end section can be the first part of the screw to penetrate the substrate. The screw tip can, for example, taper to a point at the end of the wood screw. In this case, the screw tip can, for example, be conical. Alternatively, the screw tip can, for example, terminate in a straight or curved cutting edge at the end of the wood screw.

[0022] According to an exemplary embodiment, a wood screw is designed that can be driven into a substrate (especially a wooden substrate) with high pull-out values ​​and a low tendency to split. When the wood screw is inserted (especially screwed in) into the substrate (especially made of wood), for example, using a drive tool (such as a screwdriver or a cordless drill), at least one of the arc-shaped projections reduces the otherwise existing tendency of the threads to split the substrate (especially the wood). The arc shape prevents excessive damage to the substrate material. Instead of promoting splitting of the substrate, the configuration of threads and at least one of the arc-shaped projections causes the substrate material to collect or be compacted in the area between the threads and the at least one arc-shaped projection with minimal damage.In particular, wood fibers in a wooden substrate can be compressed, compressed, split, or severed in this area. By suppressing unwanted splitting, the mechanical integrity of the wood or other substrate can be largely preserved, thereby increasing the pull-out strength of the wood screw. This high pull-out strength is further enhanced by the accumulation of wood fibers or other substrate material in the spaces between the one or more arc-shaped projections on the one hand and the threads on the other. When the wood screw is inserted into the substrate, the screw tip will initially penetrate, preferably without pre-drilling. The screw tip will then bite deeper and deeper into the substrate, with subsequent threads in the wood anchoring the wood screw.The arc-shaped projections only moderately increase the insertion force of the wood screw into the substrate, but advantageously cause a gathering, compression, or displacement of wood fibers or other substrate material without significantly damaging it. As a result, a strong anchoring force of the wood screw in the (wooden) substrate is achieved, which increases the pull-out forces. The substrate material (especially wood) remains largely intact when the wood screw is inserted, further increasing the holding power. According to an embodiment of the invention with one or more arc-shaped projections, low splitting force can thus be achieved with high pull-out forces.

[0023] Further exemplary embodiments of the screw, the methods and the use are described below.

[0024] According to one embodiment, the maximum radial extension of at least one of the arcuate projections can be smaller than the maximum radial extension of the threads. In other words, at least one of the arcuate projections, even at its most distal position, can extend less far radially from the screw axis than the radial outer edge of the threads. This prevents excessive frictional force or excessive damage to the substrate (especially wood) from at least one of the arcuate projections, thus keeping the insertion force moderate. The described configuration of at least one of the arcuate projections effectively suppresses splitting, particularly of wood, caused by the threads. Simultaneously, the anchoring force of the wood screw in the substrate can be improved.

[0025] According to a comparative example not belonging to the invention, at least one of the arc-shaped projections can extend wholly or partially in the axial direction. The arc-shaped projection can be essentially straight-line in the axial direction between a first end and a second end of the projection, wherein, in a comparative example not belonging to the invention, the ends do not extend further than the immediately adjacent threads. According to a comparative example not belonging to the invention, the arc-shaped projection can therefore extend parallel to the screw axis. Alternatively, the arc-shaped projection can also include a tangential component with respect to its direction of extension.

[0026] It is also possible that at least one of the arc-shaped projections extends at an angle of 90°, i.e., perpendicular to the threads. In this latter configuration, it is advantageous that the effective surface is oriented perpendicular to the threads, which may be tilted relative to an axial direction. The at least one projection can therefore run at an angle to the axial direction, in particular perpendicular to a given thread.

[0027] According to one embodiment, at least one end of two axially opposite ends of at least one of the arcuate projections can terminate on a flank of one of the threads. Each thread can be characterized by an ascending and a descending flank, between which lies a position of maximum radial extension of the thread. If extensions of at least one of the arcuate projections extend into an adjacent flank section of a neighboring thread, this thread and the respective arcuate projection form a particularly stable mechanical unit.

[0028] According to one embodiment, at least one end of two axially opposite ends of at least one of the arc-shaped projections can terminate precisely at a transition (in particular at a kink) between a thread and the shank. In the described embodiment, the extensions of the arc-shaped projection reach exactly to a transition between the shank and the respective thread. This allows the thread to remain unaffected, regardless of the presence of the projection. Simultaneously, a sufficiently long axial extension of at least one of the arc-shaped projections is ensured. The result is a high pull-out force with a low tendency to split, combined with a moderate settling force of the screw.

[0029] According to one embodiment, at least one end of two axially opposite ends of at least one of the arc-shaped projections on the shaft can terminate at a distance from an adjacent thread. In this configuration, the influence of the threads on the screwing process is particularly minimal, allowing for particularly low-effort insertion of the wood screw, even by hand. Simultaneously, the remaining spaces between the respective flank of the front or rear thread on the one hand and the respective end of the arc-shaped projection on the other can be filled with substrate material (especially displaced wood fibers) during insertion into the substrate, thereby increasing the pull-out force.

[0030] According to one embodiment, at least one of the arc-shaped projections can have its maximum radial extent in the axial direction midway between two adjacent threads. In particular, the local axial maximum of the arc-shaped projection, with respect to its radial distance from the shank or screw axis, can lie precisely midway between two threads immediately adjacent to the arc-shaped projection. This creates a symmetrical arrangement, which consequently leads to a symmetrical force transmission from the wood screw to the wood substrate. Zones of excessive compression of wood fibers can thus be avoided, allowing the wood material to remain largely intact and increasing the pull-out strength.

[0031] According to one embodiment, the screw tip can be conical. Such a screw tip, tapering conically towards a pointed end, allows for particularly low-force insertion of the wood screw into the substrate and a continuous widening of the substrate to prepare the ground for the subsequent insertion of the radially wider shaft with its threads into the substrate. A conical tip also protects the substrate material from excessive damage; in particular, displaced wood fibers can remain essentially intact.

[0032] According to one embodiment, at least one of the arc-shaped projections can be in its main extension direction (or longitudinal extension direction, for example the vertical direction in) Figure 2 ) and / or perpendicular to its principal direction of extension (i.e., in its transverse direction, for example the horizontal direction in Figure 2The screw has a shape selected from a group consisting of a crescent shape, a semicircular shape, and a shape with at least two overlapping (especially axially overlapping) sections of the aforementioned shapes. A crescent-shaped geometry of the at least one arc-shaped section in the axial direction is particularly preferred. This allows for particularly low-force penetration of the wood screw into the substrate, thus keeping the installation force low. Simultaneously, this enables the wood screw to be driven with gentle force applied to the substrate, protecting the latter from excessive damage and thereby increasing the pull-out strength of the wood screw.

[0033] According to one embodiment, at least one of the arc-shaped projections can extend symmetrically or asymmetrically from a central (in particular, central or axially offset from a center) position with maximum radial extension in the direction of two immediately adjacent threads towards axially opposite ends of the projection.

[0034] In particular, with respect to the position of the maximum radial extent of the arc-shaped projection, the section on the screw tip side and the section further away from the screw tip (for example, on the screw head side) can be designed to be mirror-symmetrical to each other (see for example Figures 7 to 9A corresponding mirror plane can be formed by the position of the maximum radial extent of the arc-shaped projection and perpendicular to the axial screw axis. Such a configuration results in a uniform force transmission to the different areas of the wood screw on either side of the maximum radial extent of the arc-shaped projection and the substrate. Furthermore, two mirror-image undercuts can then be formed between the projection and the adjacent threads, in which wood fibers or other displaced substrate material can be compressed and absorbed with minimal damage, further increasing the pull-out force.

[0035] Alternatively, an asymmetrical design of the arc-shaped projection in the axial direction can be used to create an asymmetrical force application in the wood screw and the substrate (see, for example, Figure 10 and Figure 11Such an arc-shaped protrusion wedges itself particularly strongly into the surrounding substrate material, especially its wood fibers. With such an asymmetrical configuration, the center of gravity of the arc-shaped protrusion can thus be shifted towards a thread closer to the screw tip or towards a thread further away. This can generate undercuts of varying degrees.

[0036] According to a preferred embodiment, at least one of the arc-shaped projections can be designed as a sharp-edged milling cutter, i.e., for removing material from the substrate by milling. Within the scope of the present application, milling can be understood in particular as a machining process for producing a borehole in the substrate with a geometrically defined shape, in which material is removed from the substrate in the form of chips. In such milling using one or more milling cutters in the form of respective arc-shaped projections, the substrate material is locally removed by the milling cutter rotating about its own axis as the wood screw is inserted into the substrate. According to such a preferred embodiment, the milling cutter with an arc-shaped milling edge can be designed as a sharp-edged milling cutter.The curved projection equipped with a cutting edge acts as a milling cutter, effectively cutting the substrate material. In this configuration, substrate material is not only displaced from the area around the curved projection but also separated or fragmented from the rest of the substrate by the cutting action. In the case of a wooden substrate, this results in the separation of wood fibers, limited to the immediate vicinity of the curved projection. Milling away substrate material leads to a lower setting force when inserting the wood screw into the substrate. Furthermore, this measure facilitates or supports the cutting of a thread in the substrate. Due to the strictly localized milling effect of at least one projection, the substrate remains largely intact, thus achieving a high pull-out force.

[0037] According to one embodiment, at least one of the arc-shaped projections can have a blunt edge. As an alternative or supplement to the embodiment described above, the arc-shaped projection can therefore be intentionally provided with a blunt outer edge to prevent shearing and thus weakening of the substrate surrounding the wood screw. Intuitively, the blunt edge leads more to compression of the wood than to splitting. This results in a particularly high pull-out force.

[0038] According to one embodiment, at least one of the arc-shaped projections can be formed entirely within the shank. In this embodiment, the shank with its threads (apart from an optional screw head) defines the radially widest area of ​​the wood screw along its axial length. If one or more radial arc-shaped projections are attached to, joined to, or molded onto the shank, a particularly wide radial displacement effect is exerted on the substrate material, thus achieving a particularly effective increase in pull-out force.

[0039] If one or more such arc-shaped protrusions are placed in the end section of the shank furthest from the screw tip (especially on the screw head side), between the threads there, the presence of these protrusions, which in a sense increases the setting force, only becomes effective at the end of the setting process. Over a longer period of the setting process, however, the arc-shaped protrusions advantageously do not lead to any increase in the setting force.

[0040] According to one embodiment, at least one of the arc-shaped projections can be formed entirely in the area of ​​the screw tip. When one or more arc-shaped projections are attached in the area of ​​the screw tip, the force is applied to the substrate material by at least one of the arc-shaped projections in a radially relatively axial area and in the area of ​​the borehole's depth. Thus, the arc-shaped projection in this area acts deep within the material, reducing gaps, stabilizing, and preventing pull-out.

[0041] According to one embodiment, at least one of the arc-shaped projections can extend between the shank and the screw tip, thus partially within the shank area and partially around the screw tip area. In the transition or bridging area between the screw tip and shank, the force exerted by the wood screw on the substrate changes during the driving process. Therefore, the risk of splitting is particularly high in this area. If an arc-shaped projection is arranged partly within the shank and partly already at the screw tip, undesirable splitting of the substrate (especially wood) can be effectively prevented, particularly at this critical point.

[0042] According to a comparative example not belonging to the invention, at least two arcuate projections can be tangentially offset from each other (i.e., in the circumferential direction of the shank, in which the threads also extend). In particular, several arcuate projections can be offset from each other by the same tangential angular distance. When several arcuate projections are arranged with an angular offset (in particular a constant one) relative to each other, a substantially symmetrical force field is also generated in the circumferential direction of the wood screw. This further reduces the tendency of the threads to cause splitting of the (in particular wood-fiber) substrate. Furthermore, circumferential weak points of the wood screw with regard to pull-out force are avoided when several angularly offset arcuate projections are formed.

[0043] According to a comparative example not belonging to the invention, several arcuate projections (in particular one or more groups of projections or even all arcuate projections) of the wood screw can be aligned in the axial direction. If all or several arcuate projections are aligned, that is, aligned along a linear imaginary connecting axis, a scraping or cutting axis can be precisely defined.

[0044] According to a preferred comparative example not belonging to the invention, the wood screw can have several axially aligned arcuate projections in the region of the screw tip and several axially aligned arcuate projections in a screw-head-side end section of the threads of the shank. In such a comparative example not belonging to the invention, which is found, for example, in Figures 1 to 6As depicted, both a splitting-inhibiting and a pull-out force-enhancing effect are created in the borehole depth as well as in the near-surface area of ​​the subsurface. This leads to particularly high pull-out values ​​with a significantly suppressed tendency to split.

[0045] According to one embodiment, the wood screw can be designed for insertion into a wooden substrate (especially a solid wood substrate) without pre-drilling. Although the wood screw can be used in various substrate materials, its use as a wood screw, i.e., for insertion into a wooden substrate, is particularly preferred. The wooden substrate is preferably a solid wood substrate with intact wood fibers before the wood screw is inserted. Alternatively, insertion into a wood composite substrate is also possible. A substrate into which a wood screw is inserted according to an exemplary embodiment of the invention can therefore consist entirely or partially of wood. For example, such a substrate could be a particleboard, an OSB (oriented strand board), or a chipboard.Wood, especially solid wood, tends to split undesirably when subjected to strong forces through sharp threads. This damages the wood substrate and reduces the holding power of a screw driven into it. If the described measures, particularly at least one of the arc-shaped projections with the described characteristics, reliably suppress the tendency of the wood fibers to split when the wood screw is driven into such a wood substrate, the wood material can accumulate in the undercut area between the arc-shaped projection and the adjacent threads, resulting in a particularly high holding power without extensive damage to the substrate.

[0046] According to one embodiment, an undercut for receiving material from a wooden substrate can be formed between each arc-shaped projection and at least one of the two adjacent threads, into which the wood screw is inserted. Wood fibers or similar materials can be forced into and compressed in such undercut volumes when the wood screw is driven into a wooden substrate.

[0047] Preferably, the wood screw is inserted into the substrate (especially wood) without pre-drilling. This allows for particularly efficient handling of the wood screw on a construction site or other application site, as the time-consuming drilling of pilot holes is unnecessary. Alternatively, if required (for example, with a particularly hard substrate), it is also possible to create such a pilot hole before inserting the wood screw, which then results in particularly low setting forces.

[0048] Preferably, the threads form a self-tapping or self-tapping thread in the wood. This promotes the reliable formation of threads in the wood substrate, in particular when the wood screw is installed without pre-drilling. This also creates a positive fit between the threads and the wood substrate, which in turn increases the pull-out force.

[0049] According to an exemplary embodiment, the flank angle of at least some of the threads can lie in a range between approximately 30° and approximately 70°, particularly in a range between approximately 40° and approximately 60°. Such flank angles are advantageous for achieving particularly good holding power, as the thread flanks can then engage the wood efficiently.

[0050] According to one exemplary embodiment, the screw tip can taper to a substantially point-like end of the wood screw. According to another exemplary embodiment, the screw tip can have at least one end-cutting edge. Thus, there are various possibilities regarding the design of the screw tip, whereby the screw tip can advantageously be configured so that the wood screw can be driven into a solid wood substrate without pre-drilling.

[0051] According to a first embodiment, the screw tip can taper to a point-shaped end of the wood screw, with the thread extending directly from this point-shaped end along the screw tip and further along the shank. Such an embodiment is described in Figure 1 As shown, if the thread starts directly at the pointed end, the thread can engage immediately when the pointed end is placed on the (especially unpre-drilled) surface of a wooden substrate and begin self-tapping into the substrate. This design of the screw tip eliminates the need for pre-drilling and allows for effortless insertion, as the forced feed of the thread assists the installer right from the start of the installation process.

[0052] According to an alternative second embodiment, the screw tip can be designed as a drill point with at least one end cutting edge. Such a cutting edge, for example a linear sharp edge, can be designed as at least one main cutting edge and, like a drill bit, create a hole in a wooden substrate. Optionally, at least one transverse cutting edge can also be provided at the drill point, as is known to those skilled in the field of screws and drill bits.

[0053] According to an exemplary embodiment, the head or free end of a wood screw can be provided with a drive for rotating the screw. This drive serves to create a positive-locking connection with a tool for driving the screw, such as a manual screwdriver or a motorized setting tool (e.g., a cordless screwdriver). The rear end of the wood screw can thus be formed by the screw head with a drive for rotating the screw. The drive can be a slotted drive, a Phillips drive, an Allen drive, a Torx drive, or an Allen drive.

[0054] According to an exemplary embodiment, the wood screw can optionally have a threadless section between the screw head and the threaded shank. Visually, the threaded shank can extend on the back side to a smooth, threadless area of ​​the wood screw. This allows the axial length of the wood screw to be increased without excessively increasing the thread length.

[0055] According to an exemplary embodiment, the wood screw can be driven by rotating a drive mechanism (for example, on an end face of the screw head, on a free end of the shank, or on an unthreaded section). For example, a manually operated screwdriver or a motor-driven screw gun can be used to drive the wood screw into the substrate. A self-tapping thread on the wood screw can provide forced feed into the substrate, enabling the screw to penetrate axially with minimal effort.

[0056] According to one embodiment, the wood screw can be formed by means of cold forming (to form the head or drive), pinching (to form the screw tip) and rolling (to form the thread).

[0057] According to an exemplary embodiment, the protrusion can be formed at least partially during the thread rolling process. This involves only a sufficient redistribution of material to create the protrusion, thus eliminating the need to add or remove material to form the protrusion(s).

[0058] According to an exemplary embodiment, at least one of the protrusions can be formed, at least partially, when the screw tip is crimped. According to this embodiment as well, at least one of the protrusions can be produced without requiring a separate operation.

[0059] According to an exemplary embodiment, the wood screw can have at least one further projection extending over one of the threads, in particular intersecting one of the threads. Such a further projection can extend from the (in particular circular cylindrical) shank and / or from the (in particular conical) screw tip. A first section of such a further projection can be arranged on one side (for example, a screw head-side side) of an associated thread, whereas an opposing second section of such a further projection can be arranged on an opposing other side (for example, a screw tip-side side) of the associated thread. Such a further projection or several such further projections can beThese projections can therefore have a different angle with the axial direction of the wood screw, in particular a smaller angle with the axial direction of the wood screw, than the thread crossing the respective projection. One or more such projections can also help to displace wood fibers when the wood screw is driven into a wooden or wood-based substrate, thus facilitating the insertion of the wood screw into the substrate for a user with moderate torque, or promoting the widening of the borehole on its outer surface. Further projections in a transition area between the threaded section and a non-threaded section (which may have a slightly larger outer diameter than the threaded section) can suppress wood spreading when the non-threaded section, with its slightly larger outer diameter, penetrates the wooden substrate.In this way, the additional projections can prepare the hole area at the transition between the threaded and unthreaded sections. At the same time, the function of these additional projections prevents excessive damage to the wood substrate, thus enabling high pull-out forces.

[0060] According to one embodiment, the further projection can be designed as a milling edge (to process wood material by milling) or blunt (i.e. for pure material displacement of wood).

[0061] According to an exemplary embodiment, at least one further projection can be provided as an alternative or supplement to at least one of the projections between the threads.

[0062] According to an exemplary embodiment, the at least one further projection can be arc-shaped, in particular crescent-shaped. More generally, the at least one further projection can have a shape in its main direction of extension and / or perpendicular to its main direction of extension, selected from a group consisting of a crescent shape, a semicircular shape, and a shape with at least two overlapping (in particular, overlapping in the axial direction) sections of the aforementioned shapes. A crescent-shaped geometry of the at least one further projection in the axial direction or tilted to the axial direction is particularly preferred. The described shape enables particularly low-torque penetration of the wood screw into the substrate and simultaneously protects the respective further projection from excessive damage.

[0063] According to an exemplary embodiment, the wood screw can have a plurality of additional projections extending over one of the threads, spaced apart from each other tangentially or circumferentially, and arranged angularly offset around the shank. Thus, one of the threads can be provided with several additional projections (particularly equidistantly) offset from each other in the circumferential direction. In the area of ​​this one or these multiple threads, which is or are provided with additional projections, a targeted and defined widening of the borehole can then occur without significant damage to the associated wood fibers.

[0064] According to an exemplary embodiment, the at least one further projection can be formed in a region of the shank to which a screw head or a bolt-free section adjoins. In particular, the at least one further projection can be located in a region of the shank opposite the screw tip. The at least one further projection can intersect one of the two threads furthest from the screw tip. Furthermore, and in particular, the at least one further projection can (and even more specifically, can only) intersect one thread furthest from the screw tip.

[0065] According to an exemplary embodiment, the at least one additional projection can have its maximum radial extent in the region of a respective maximum of the respective thread pitch. Visually, the additional projection can grow out of the shank, reach its radial maximum in the intersection area with the associated thread pitch, and subsequently grow back into the shank.

[0066] According to an exemplary embodiment, the maximum radial extent of the at least one additional projection can be less than the maximum radial extent of the associated thread. This ensures that the at least one additional projection does not impair the thread-forming function of the threads. Nevertheless, the at least one additional projection can still perform its wood-displacing and, if necessary, milling function. In the region of the radial maximum of the additional projection, it can therefore extend less far outwards in the radial direction than the crossed thread. This also prevents excessive enlargement of the borehole and excessive damage to the wood material, thus enabling high pull-out forces to be achieved.

[0067] According to an exemplary embodiment, at least one of the projections and at least one further projection can be arranged at an acute angle to an axial direction of the shaft. In this configuration, the main direction of the projection or further projection deviates from an axial direction of the shaft. It has been found that a slight inclination of the respective projection or further projection is advantageous for force transmission into the substrate and allows for the combination of moderate setting forces and high pull-out forces.

[0068] According to an exemplary embodiment of the invention, each of the additional projections, or projections, that intersects a thread can have a direction of extension perpendicular to that thread. In other words, such an additional projection can intersect the associated thread at a right angle. According to such an embodiment, both the thread and the associated projection can be arranged obliquely to the screw axis. This geometry results in favorable force transmission.

[0069] Alternatively or additionally, it is also possible for one or more of the protrusions arranged between two adjacent threads to have a direction of extension perpendicular to these two adjacent threads. According to such an embodiment, both these threads and the associated protrusion can be arranged at an angle to the screw axis. It has been found that such a configuration is advantageous with regard to the force transmission from the wood screw into the substrate.

[0070] According to an exemplary embodiment, at least one of the threads in the region of the screw tip, particularly in the region of the foremost thread at the screw tip, can have at least one notch, and in particular several notches offset from one another circumferentially. For example, three such notches (for example, at angular intervals of 120° each) can be formed circumferentially on the foremost thread at the screw tip in the form of radial indentations. Such notches can advantageously contribute to mechanically weakening the substrate (especially wood) at the beginning of the setting process and thus preparing it for the setting of the screw remnant. In the transition area between each notch and the subsequent section of the associated thread, a sharp edge or tooth is formed, which can work its way into the wood material.In order not to weaken the wood material excessively, a notch or notches may only be formed in the foremost thread or the thread closest to the screw tip.

[0071] Exemplary embodiments of the present invention are described in detail below with reference to the following figures. Figure 1 shows a wood screw in a front view according to a comparative example not belonging to the invention. Figure 2 shows the wood screw according to Figure 1 in a side view. Figure 3 shows the wood screw according to Figure 1 in a cross-sectional view along a section plane AA according to Figure 2 . Figure 4 shows the wood screw according to Figure 1 in a top view. Figure 5 shows detail B of the wood screw according to Figure 1 , compare Figure 3 . Figure 6 shows the wood screw according to Figure 1 in a bottom view. Figures 7 to 11Show details of arc-shaped projections in intermediate thread sections between adjacent threads of wood screws according to exemplary embodiments of the invention. Figure 12 The figure schematically shows a section of a wood screw according to an exemplary embodiment, in which several arc-shaped projections are offset from each other by an equal tangential angular distance of 90°. Figure 13 shows a wood screw according to a comparative example not belonging to the invention after being screwed into a wooden substrate. Figure 14 shows a side view of a shaft section of a wood screw according to another exemplary embodiment of the invention. Figure 15 shows another side view of the shaft section according to Figure 14 . Figure 16 shows an enlarged view of a screw tip-side end region of the shaft section according to Figure 14 and Figure 15 . Figure 17shows a cross-sectional view corresponding to a section line AA according to Figure 16 . Figure 18 shows a cross-sectional view corresponding to a section line BB according to Figure 15 . Figure 19 shows a cross-sectional view corresponding to a section line CC according to Figure 16 . Figure 20 shows a cross-sectional view corresponding to a section line GG according to Figure 15 . Figure 21 shows a cross-sectional view corresponding to a section line DD according to Figure 14 . Figure 22 shows the wood screw according to Figures 14 to 21 without showing overhangs (i.e., the overhangs are in Figure 22 (hidden). Figure 23 shows a three-dimensional view of the shaft section according to Figures 14 to 22 .

[0072] Identical or similar components in different figures are provided with the same reference numerals.

[0073] Before describing exemplary embodiments of the invention with reference to the figures, some general aspects of the invention will be explained: According to an exemplary embodiment of the invention, a projection, preferably designed as a milling cutter, is formed in an arc shape between two adjacent threads on a shank, a screw tip, one or more threads, and / or a transition between at least two of the aforementioned elements. The ends of the arc-shaped projection, preferably designed as a milling cutter, can terminate on an adjacent thread flank or where the thread flank meets the shank. It is also possible for the arc-shaped projection to terminate at a distance from the adjacent thread flank.Thus, a valley (preferably in the axial direction) remains between the maximum height of the arc-shaped projection (in particular, the milling cutter) and the adjacent thread flank, between which the wood (or other substrate material into which the wood screw is inserted) is not affected, or only minimally affected, when the wood screw is driven in. When the wood screw is driven into wood or another substrate material, wood or other material remains between the arc-shaped projection, preferably designed as a milling cutter, and the threads in the axial direction, which is not engaged by either the arc-shaped projection or the thread. If the installed wood screw is pulled (for example, during a pull-out test), the forces introduced are transferred via the thread flanks into the wood or other substrate material. Because the arc-shaped projection, when the wood screw is driven in, engages the wood or other substrate material, the resulting forces are not affected.Since the other substrate material near the thread flanks remains virtually unaffected, the load-bearing wood or other substrate material remains almost undisturbed, leading to increased pull-out forces. The arc-shaped projection, designed specifically as a milling cutter, reduces the screw-in torque of the wood screw and the radial displacement pressure of the wood or other material on the thread core. This effect is particularly pronounced due to the milling action of the arc-shaped projection.

[0074] The greatest splitting effect when driving a wood screw into a substrate, especially one made of wood, occurs at the thread flank tips. This happens regardless of whether the advantageously designed, arc-shaped projection terminates axially on the thread flank or not. However, if the arc-shaped projection terminates at a distance from the thread flank, more wood or other material remains in the radially lower region of the thread flank (i.e., in the area closest to the shank), which increases the pull-out force.

[0075] A significant splitting effect occurs in the core of the threads at the midpoint between two adjacent thread flanks. This is particularly true regardless of whether an arc-shaped projection, advantageously designed as a milling cutter, is present or not. Because the arc-shaped projection can have its maximum radial height midway between the adjacent thread flanks, it minimizes the splitting effect precisely where it is greatest.

[0076] A wood screw according to an exemplary embodiment of the invention can have a conical tip, a shank with a thread (formed by the threads), and a screw head with a drive. An arc-shaped projection of a wood screw, designed as a milling cutter, according to an exemplary embodiment of the invention preferably extends in a crescent shape between two adjacent thread flanks. Its radial height can be highest midway between the adjacent thread flanks and decrease from there to its two ends. The arc-shaped projection, preferably designed as a milling cutter, is preferably symmetrical about this maximum height. The ends of the arc-shaped projections can terminate at a distance from the adjacent thread flanks.

[0077] The cross-section of the arc-shaped projection, preferably designed as a milling cutter, can be triangular, square, rectangular, or trapezoidal, with hybrid shapes also being possible. The edges of the arc-shaped projection can be rounded or sharp-edged along their height. In the first case, the arc-shaped projection acts primarily as a displacement element. In the second case, the arc-shaped projection acts primarily as a milling cutter, i.e., cutting. Hybrid shapes combining the two aforementioned embodiments are possible, for example, an arc-shaped projection with a milled-edge section and a blunt-edged section. At least one arc-shaped projection, preferably designed as a milling cutter, can be arranged only in the region of a conical screw tip or only in the shank section. It is also possible for such an arc-shaped projection to be arranged in both the conical tip and the shank section.This applies analogously to "displacers".

[0078] According to an exemplary embodiment of the invention, arc-shaped projections of a wood screw can be arranged at an angle to one another. For example, the arc-shaped projections (particularly designed as milling cutters) can have an equal angular distance between them.

[0079] According to one exemplary embodiment, the ends of the arc-shaped projections terminate at a distance from the thread flanks. It is also possible, according to another exemplary embodiment of the invention, for one or more arc-shaped projections to terminate where the thread flanks meet the thread core or on the thread flanks themselves. Hybrid forms consisting of two or three of the three aforementioned pure forms are possible. The arc-shaped projections, which are particularly designed as milling cutters, are preferably configured with mirror symmetry. This means that the end section extending from the highest radial extent towards the screw tip can be configured in the same way as the other end section extending from there towards the screw head. However, in another embodiment, the progression is not mirror symmetry. For example, the maximum radial height can be shifted on the screw tip side or on the screw head side.

[0080] Figure 1 Figure 100 shows a wood screw according to a comparative example not belonging to the invention in a front view. Figure 2 The wood screw 100 shows according to Figure 1 in a side view. Figure 3 The wood screw 100 shows according to Figure 1 in a cross-sectional view along a Figure 2 defined cutting plane AA. Figure 4 The wood screw 100 shows according to Figure 1 in a top view. Figure 5 shows detail B (compare) Figure 3 ) the wood screw 100 according to Figure 1. Figure 6 The wood screw 100 shows according to Figure 1 in a bottom view.

[0081] The in Figure 1 The illustrated wood screw 100 is designed as a wood screw and is made of steel, another metal, or plastic. More precisely, the wood screw 100 is designed as a wood screw for pre-drilling-free and self-tapping or thread-forming insertion into a wooden substrate 124 (see Figure 13 The wood screw 100 is designed and constructed as follows: It has a screw head 132, a threadless bolt section 144, a circular cylindrical shaft 102, a conical screw tip 104, and helical threads 106. The threads 106 extend radially beyond the shaft 102 and screw tip 104, respectively, and helically circumferentially over a portion of the shaft 102 into the screw tip 104. Continuously curved, dome-shaped or arcuate projections 108 are formed in some axial regions of the wood screw 100 between two adjacent threads 106.

[0082] How Figure 1 and Figure 2 As can be seen, the maximum radial extent r (compare Figure 7 ) the arc-shaped overhangs 108 smaller than a maximum radial extent R (compare Figure 7) of the threads 106, which promotes low-force setting of the wood screw 100 and undisturbed thread cutting. Apart from the screw head 132, the threads 106, followed by the optional unthreaded bolt section 144 and the arcuate projections 108, therefore form the radially outwardly extending sections of the wood screw 100. Furthermore, the projections 108 extend in an arcuate direction 110, i.e., in a direction parallel to a screw axis or a central axis or axis of symmetry 140 of the circular cylindrical shaft 102. A respective end 112, 114 (compare Figure 7The arc-shaped projections 108, extending from two axially opposite ends 112, 114, terminate at a respective step-like transition or kink 118 between a thread 106 and the shank 102. Furthermore, the arc-shaped projections 108 have their respective maximum radial extent r axially exactly midway between two adjacent threads 106. In addition, the arc-shaped projections 108 have a crescent shape. Advantageously, in the comparative example shown, the arc-shaped projections 108 are designed as sharp-edged milling cutters.

[0083] Some of the arcuate projections 108 are formed entirely within the shank 102. Other arcuate projections 108 are formed entirely within the screw tip 104. Further arcuate projections 108 extend in a transition region between the shank 102 and the screw tip 104, bridging the latter, i.e., they have a shank-related section and a screw tip-related section. Respective groups of arcuate projections 108 are aligned with each other in the axial direction 110, i.e., they are axially aligned with each other. Projections 108 from different groups are tangentially offset from each other. More precisely, in the comparative example according to Figures 1 to 6Several arc-shaped projections 108 aligned in the axial direction 110 in the area of ​​the screw tip 104 and several arc-shaped projections 108 also aligned in the axial direction 110 in a screw head-side end section 122 of the threads 106 of the shaft 102 are provided.

[0084] The arc-shaped projections 108 of the wood screw 100 are designed as milling cutters and thus facilitate the low-effort driving of the wood screw 100 into a wooden substrate 124. They also reduce the tendency of the wood to split under the influence of the threads 106 and furthermore increase the pull-out force of the wood screw 100 after it has been set into a wooden substrate 124. The arc-shaped projections 108 also displace wood into the undercuts 138 formed (see Figures 7 to 11 ) between the arc-shaped projections 108 and the adjacent threads 106, thereby further increasing the pull-out force of the wood screw 100.

[0085] According to Figures 1 to 6 The screw tip 104 is conical and terminates in a screw tip endpoint 134. When the wood screw 100 is placed on a wooden substrate 124 with the screw tip endpoint 134 and set in rotation by means of a drive tool (for example, a screwdriver or a cordless drill, not shown), the screw tip endpoint 134 first penetrates the wood, causing the threads 106, which extend into the screw tip 104, to engage and self-tapping or self-grooving as they rotate into the wooden substrate 124. The arc-shaped projections 108 of the wood screw 100, designed as milling cutters, according to Figures 1 to 6The sharp cutting edges of the screws then cut away wood material in the area of ​​the crest of the arcuate projections 108 and displace wood fibers into the spaces between the arcuate projections 108 and the threads 106. The wood remains largely intact. The setting process is complete when the underside of the screw head 132 abuts an outer surface of the wooden substrate 124. Of course, the insertion of the wood screw 100 into the wooden substrate 124 can also be stopped earlier. Furthermore, it is possible to insert another element, such as a washer, between the screw head 132 and the wooden substrate 124. Figure 1The figure also shows smooth intermediate thread sections 126 of the circular cylindrical shaft 102 between adjacent threads 106, free of arcuate projections 108. In other intermediate thread sections 126, the axially extending crescent-shaped arcuate projections 108 are integrally formed with the wood screw 100 at the described locations. Since the opposing ends 112, 114 or extensions of the arcuate projections 108 reach to the flanks of the adjacent threads 106, free areas are formed between the thread 106 and the projection 108 in the form of undercuts 138. These areas fill with wood fibers during the insertion of the wood screw 100 and thus additionally prevent the wood screw 100 from being pulled out of the wooden substrate 124 by means of a positive locking, frictional locking, or force locking effect.

[0086] As in Figure 4As shown, the screw head 132 has a central area 136 of an end face, which can have a drive (for example, a slotted drive, a Phillips drive, a hexagonal drive, an Allen drive, etc.) not shown in the figure. This allows a drive tool (also not shown in the figure) to engage forcefully with the screw head 132 and thereby transmit a torque from the drive tool to the wood screw 100.

[0087] Figures 7 to 11 show details of arc-shaped projections 108 in intermediate thread sections 126 between adjacent threads 106 of a wood screw 100 according to exemplary embodiments of the invention.

[0088] According to Figure 7 The two axially opposite ends 112, 114 of the illustrated arc-shaped projection 108 terminate on the shaft 102 at an axial distance from an adjacent thread 106. Thus, the projection 108 terminates according to Figure 7on both sides in the area of ​​the shaft 102. The arc-shaped projection 108 shown also extends symmetrically from a position with maximum radial extent r in the direction of the two immediately adjacent threads 106. As in Figure 7 As shown, in cross-section the arc-shaped section 108 is radially offset from the threads 106. This ensures that the self-tapping of a helical mating thread in the wooden substrate 124, which is inverse to the threads 106, is not disturbed by the arc-shaped projection 108 (r <R). Zwischen dem bogenförmigen Überstand 108 einerseits und den zwei daran angrenzenden Gewindegängen 106 ist ein jeweiliger Hinterschnitt 138 zum Aufnehmen von Material eines Holzuntergrunds 124 (siehe Figure 13) formed, into which the wood screw 100 is inserted. The undercuts 138 between the arc-shaped projection 108 and the adjacent threads 106 fill with compressed wood fibers when the wood screw 100 is driven into a wooden substrate 124. As also in Figure 7 As shown, the threads 106 have a substantially triangular cross-section. The projection 108, on the other hand, has the shape of a dome or a crescent moon.

[0089] Unlike Figure 7 is according to Figure 8 The arc-shaped projection 108 is designed such that it extends to an edge between the cylindrical surface of the shaft 102 and the flank of the threads 106 sloping towards the shaft 102. This results in a particularly deep undercut 138 and thus a strong positive fit between the wood screw 100 and the displaced wood material.

[0090] According to Figure 9Both axially opposite ends 112, 114 of the illustrated arc-shaped projection 108 terminate on a flank 116 of one of the respective threads 106, i.e., they do not extend radially to the shank 102 at the exposed ends 112, 114. Figure 9 The undercut 138 is less pronounced. However, the lesser convex curvature of the arc-shaped projection 108 leads to the following Figure 9 This further reduces the driving force of the wood screw 100 into the wooden substrate 124.

[0091] The examples of implementation according to Figures 7 to 9 They all show a mirror-symmetrical configuration of the arc-shaped projection 108 with respect to an axis of symmetry 140. This structural symmetry leads to a symmetrical force introduction into the wood screw 100 and consequently to the avoidance of force peaks.

[0092] According to Figure 10The arc-shaped projection 108 shown extends from a position with maximum radial extent r in axial (i.e., according to Figure 10 horizontal) direction asymmetrically in the direction of two adjacent threads 106 towards the ends 112, 114. Thus, according to Figure 10 The material distribution in the arc-shaped projection 108 between the adjacent threads 106 is asymmetrical and shifted predominantly to the left. In other words, the position of maximum radial extent (r) of the arc-shaped projection 108 is as follows: Figure 10 closer to one adjacent thread 106 than to the other adjacent thread 106. This allows a narrow deep and a wide shallow undercut 138 to be achieved, whereby the pull-out force can be further increased by this asymmetrical configuration.

[0093] According to Figure 11The arc-shaped projection 108 shown extends from a position with maximum radial extent r also asymmetrically in the direction of two adjacent threads 106. Figure 11 shows a similar embodiment Figure 10 , whereby according to Figure 11 the asymmetrical material distribution of the arc-shaped overhang 108 is shifted to the right instead of to the left, i.e. away from end 112 and towards end 114.

[0094] Figure 12 Figure 1 shows a highly schematic section of a wood screw 100 according to an exemplary embodiment, in which several arc-shaped projections 108 are offset from each other by the same tangential angular distance of here 90°. Figure 12Figure 1 shows a top view of a cross-section of a wood screw 100 according to an exemplary embodiment of the invention and illustrates that, in this case, four angle-symmetrically distributed arc-shaped projections 108 are formed on the shaft 102. According to this embodiment, the relative angular distance between two adjacent arc-shaped projections 108 is 90°. This results in a force application symmetrically in the tangential direction into the wooden substrate 124 and in reliable anchoring.

[0095] Figure 13 shows a wood screw 100 according to a comparative example not belonging to the invention after being screwed into a wooden substrate 124. More precisely, shows Figure 13 the result of driving in a 100 mm wood screw, as in Figures 1 to 6The wooden substrate 124, made of solid wood, is shown. A detail 148 schematically illustrates how wood fibers 142 accumulate in the area of ​​the arched projections 108, or are forced or compressed there. This increases the pull-out force without excessively damaging the wood material of the wooden substrate 124. An optional washer 150 is also shown.

[0096] Figure 14 shows a side view of a shaft section of a wood screw 100 according to another exemplary embodiment of the invention. Figure 15 shows another side view of the shaft section according to Figure 14 . Figure 16 shows an enlarged view of a screw tip-side end region of the shaft section according to Figure 14 and Figure 15 . Figure 17 shows a cross-sectional view corresponding to a section line AA according to Figure 16. Figure 18 shows a cross-sectional view corresponding to a section line BB according to Figure 15 . Figure 19shows a cross-sectional view corresponding to a section line CC according to Figure 16. Figure 20 shows a cross-sectional view corresponding to a section line GG according to Figure 15 . Figure 21 shows a cross-sectional view corresponding to a section line DD according to Figure 14 . Figure 22 The wood screw 100 shows according to Figures 14 to 21 without showing protrusions 108. Figure 23 shows a three-dimensional view of the shaft section according to Figures 14 to 22 .

[0097] The in Figures 14 to 23 The illustrated wood screw 100 is also designed for self-tapping or thread-forming insertion into a wooden substrate without pre-drilling. The wood screw 100 has a screw head 132 with a drive 166 (compare Figure 22), an optional unthreaded bolt section 144, a circular cylindrical shaft 102, a conical screw tip 104, and helical threads 106. The threads 106 extend from a screw tip endpoint 134 over the shaft 102 and, in the illustrated embodiment, terminate at the optional unthreaded bolt section 144 or, alternatively, extend to the screw head 132 (not shown). The screw head 132 has the Figure 22The drive 166 shown allows a drive tool (not shown) to engage positively in the screw head 132 and thereby transmit a torque from the drive tool to the wood screw 100. The screw tip 104 is conical and terminates in the point-shaped screw tip end 134. The threads 106 extend radially beyond the shaft 102 or screw tip 104 and helically circumferentially over a portion of the shaft 102 into the screw tip 104.

[0098] Continuously curved, dome-shaped, arcuate, or crescent-shaped projections 108 are formed in some axial regions of the wood screw 100 between two adjacent threads 106 and are tilted at an acute angle (for example, in a range between 5° and 40°) relative to an axial direction 110 of the wood screw 100. These projections 108 are located in the region of the screw tip 104 and in an adjacent region of the shank 102. Each end 112, 114 of two axially opposite ends 112, 114 of these arcuate projections 108 terminates at a kink or at a transition between a thread 106 and the shank 102. Furthermore, these arcuate projections 108 have their respective maximum radial extent approximately midway between two adjacent threads 106.

[0099] Other such projections, for example crescent-shaped ones 108, extend over a thread 106, i.e., cross it. In the illustrated embodiment, these latter projections 108 are formed in a region of the shaft 102 to which the unthreaded bolt section 144 adjoins. These arc-shaped projections 108 have their respective maximum radial extent in the region of a respective maximum of the respective thread 106.

[0100] The maximum radial extent of both types of projections 108 (i.e., those between threads 106 and those that cross a thread 106 in the axial direction) is smaller than the maximum radial extent of the threads 106. Therefore, apart from the screw head 132, the threads 106 form the radially outermost sections of the wood screw 100.

[0101] Furthermore, in the illustrated embodiment, all projections 108 extend in an arc at an acute angle to an axial direction 110, i.e., they are tilted relative to the axial direction 110. Alternatively, the projections 108 arranged between threads 106 and / or the projections 108 that cross the threads 106 can also be arranged extending along the axial direction 110. In particular, a projection 108 between threads 106 can be arranged perpendicular to these threads 106. Alternatively or additionally, another projection 108 that crosses a thread 106 can be arranged perpendicular to this thread 106. It is also possible for the projections 108 arranged between threads 106 and the further projections 108 crossing a thread 106 to be arranged parallel to each other.

[0102] The arc-shaped projections 108 running between and crossing the threads 106 are designed as milling cutters according to the described embodiment and thus support or facilitate the screwing of the wood screw 100 into a wooden substrate.

[0103] The arc-shaped projections 108 that cross the threads 106 can help to displace wood fibers when the wood screw 100 is inserted into a wooden or wood-based substrate, thus promoting the widening of the borehole on its outer surface. These projections 108 are located in a transition area between the shank section with the threads 106 and the unthreaded bolt section 144 (which, as shown in Figure 14 and Figure 15(as shown, which can have a slightly larger outer diameter than the shank section with the threads 106) can suppress spreading of the wood when the unthreaded bolt section 144 penetrates the wood substrate. In this way, the additional projections 108 can prepare the hole at the transition between the unthreaded bolt section 144 and the shank section with the threads 106. They also reduce the tendency of the wood to split under the influence of the threads 106.

[0104] The arched overhangs also displace 108 wood into formed undercuts (compare reference numeral 138 in the Figures 7 to 11 ) between the arc-shaped projections 108 and the adjacent threads 106.

[0105] When the wood screw 100 is placed on a wooden surface with its tip endpoint 134 and rotated using a drive tool (for example, a screwdriver or a cordless drill, not shown), the tip endpoint 134 penetrates the wood first. This causes the threads 106, which extend into the screw tip 104, to engage and self-tapping or self-grooving as they rotate into the wood. The arc-shaped projections 108 of the wood screw 100, which act as cutters, then cut away wood material in the area of ​​the crest of the arc-shaped projections 108 and displace wood fibers into the spaces between the arc-shaped projections 108 and the threads 106. The wood remains largely intact in the process.

[0106] As in Figure 16As shown, three small notches 199 or indentations are formed in the area of ​​the foremost thread 106 at the screw tip 104. These can be arranged, for example, at an angular interval of 120° to each other. Visually, the notches 199 can form teeth in the form of indentations in the thread 106, which promote penetration into the wood substrate at the beginning of the setting process of the wood screw 100.

[0107] A first aspect of the invention relates to a wood screw 100, comprising: a shank 102; a screw tip 104; threads 106 which extend circumferentially on at least a part of the shank 102, preferably into the screw tip 104; at least one arc-shaped projection 108 between at least two adjacent threads 106.

[0108] A second aspect of the invention relates to a method for manufacturing a wood screw 100, wherein the method comprises: forming a shaft 102 and a screw tip 104 axially adjoining it; forming threads 106 which extend circumferentially over at least a part of the shaft 102, preferably into the screw tip 104; forming at least one arc-shaped projection 108 between at least two adjacent threads 106 on the shaft 102 and / or on the screw tip 104.

[0109] It should also be noted that "having" does not exclude any other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above, provided that such combinations fall within the scope of the appended claims. Reference numerals in the claims are not to be considered as a limitation.

Claims

1. Wood screw (100) comprising: a shaft (102); a screw tip (104); threads (106) extending circumferentially on at least a portion of the shaft (102), preferably extending into the screw tip (104); a first group with at least one arcuate projection (108) between two adjacent threads (106) and a second group with at least one arcuate projection (108) between two other adjacent threads (106), wherein a main direction of the respective projection (108) in a top view of the wood screw (100) is tilted counterclockwise by an angle between 5° and 40° relative to an axial direction (110) of the wood screw (100), and all projections (108) are arranged so that they are not aligned with each other.

2. Wood screw (100) according to claim 1, wherein a maximum radial extension (r) of at least one of the arcuate projections (108) is smaller than a maximum radial extension (R) of the threads (106).

3. Wood screw (100) according to claim 1 or 2, wherein at least one of the arcuate projections (108) extends at an angle of 90° to the threads (106).

4. Wood screw (100) according to one of claims 1 to 3, having at least one of the following features: at least one end (112) of two axially opposite ends (112, 114) of at least one of the arcuate projections (108) ends on a flank (116) of one of the threads (106); at least one end (112) of two axially opposite ends (112, 114) of at least one of the arcuate projections (108) ends at a bend (118) between a thread (106) and the shaft (102); at least one end (112) of two axially opposite ends (112, 114) of at least one of the arcuate projections (108) ends on the shaft (102) at a distance from an adjacent thread (106).

5. Wood screw (100) according to one of claims 1 to 4, wherein at least one of the arcuate projections (108) has its maximum radial extension (r) centrally between two adjacent threads (106).

6. Wood screw (100) according to one of claims 1 to 5, wherein the screw tip (104) is conical or has a drill tip.

7. Wood screw (100) according to one of claims 1 to 6, having at least one of the following features: wherein at least one of the arcuate projections (108), in particular in its main direction of extension and / or perpendicular to its main direction of extension, has a shape selected from a group consisting of a crescent shape, a semicircular shape, and a shape with at least two sections of the aforementioned shapes merging into one another, in particular merging into one another in the axial direction; wherein at least one of the arcuate projections (108) extends symmetrically or asymmetrically from a central position with maximum radial extension (r) to opposite ends (112, 114) of the projection (108) in the direction of two adjacent threads (106), but in particular not extending axially beyond them; wherein at least one of the arcuate projections (108) is designed as a sharp-edged cutter; wherein at least one of the arcuate projections (108) is designed with a blunt edge; wherein at least one of the arcuate projections (108) is formed only in the region of the shank (102); wherein at least one of the arcuate projections (108) is formed only in the region of the screw tip (104); wherein at least one of the arcuate projections (108) extends in a transition region between the shaft (102) and the screw tip (104); wherein a plurality of arcuate projections (108) are offset from one another by a respective equal tangential angular distance; wherein an undercut (138) is formed between a respective arcuate projection (108) on the one hand and at least one of the respective two adjacent threads (106) on the other hand, for receiving material from a wooden substrate (124) when the wood screw (100) is inserted into the wooden substrate (124); designed for insertion into a wooden substrate (124) without pre-drilling.

8. Wood screw (100) according to one of claims 1 to 7, comprising at least one further projection (108) which extends across one, in particular exactly one, of the threads (106), in particular crosses one of the threads (106).

9. Wood screw (100) according to claim 8, having at least one of the following features: wherein the at least one further projection (108) is arcuate, in particular crescent-shaped; having a plurality of further projections (108) extending over one, in particular exactly one, of the threads (106), which are spaced apart from each other in the tangential direction and are arranged circumferentially around the shaft (102); wherein the at least one further projection (108) is formed in a region of the shaft (102) adjoining a screw head (132) or a threadless bolt section (144); wherein the at least one further projection (108) has its maximum radial extension in the region of a respective maximum of the respective thread pitch (106); wherein a maximum radial extension of the at least one further protrusion (108) is less than a maximum radial extension of the associated thread pitch (106).

10. Wood screw (100) according to one of claims 8 and 9, wherein at least one of the protrusions (108) and the at least one further protrusion (108) is arranged at an acute angle to an axial direction (110) of the shaft (102).

11. Wood screw (100) according to one of claims 1 to 10, having at least one of the following features: wherein at least one of the projections (108) is arranged perpendicular to the two adjacent threads (106) between which the at least one of the projections (108) is arranged; wherein the at least one further protrusion (108) is arranged to extend perpendicularly to the thread (106) over which the at least one further protrusion (108) extends.

12. Wood screw (100) according to one of claims 1 to 11, wherein at least one of the threads (106) in the region of the screw tip (104), in particular in the region of a foremost thread (106) at the screw tip (104), has at least one notch (199), in particular a plurality of notches (199) offset from one another in the circumferential direction.

13. Method for inserting a wood screw (100) according to one of claims 1 to 12 into a wooden substrate (124), wherein the method comprises: providing the wooden substrate (124), in particular without pre-drilling; in particular, pre-drill-free and / or self-drilling screwing of the wood screw (100) into the wood substrate (124).

14. Method for manufacturing a wood screw (100), wherein the method comprises: forming a shaft (102) and a screw tip (104) axially connected thereto; forming threads (106) that extend circumferentially over at least part of the shaft (102), preferably into the screw tip (104); forming a first group with at least one arcuate projection (108) between at least two adjacent threads (106) and forming a second group with at least one arcuate projection (108) between two other adjacent threads (106) on the shaft (102) and / or on the screw tip (104), wherein a main direction of the respective protrusion (108) in a top view of the wood screw (100) is tilted counterclockwise by an angle between 5° and 40° relative to an axial direction (110) of the wood screw (100), and all protrusions (108) are arranged so that they are not aligned with each other.

15. Use of a wood screw (100) according to one of claims 1 to 12 for insertion into a wooden substrate (124), in particular without pre-drilling and / or thread cutting.