Screw and screw system

Abstract

screw (100a, 100b, 100c, 100d, 100e) comprising - an upper shaft section (110) and - a lower shaft section (120) with a threaded section (125), wherein the upper shaft section (110) has a larger diameter (d1) than the diameter (d2) of the lower shaft section (120), characterized by the fact that a milling section (130, 131, 132) is provided between the upper shank section (110) and the lower shank section (120), wherein the milling section (130, 131, 132) has a larger effective cutting diameter (d3) than the diameter (d1) of the upper shank section (110).

Description

[0001] The invention relates to a screw comprising an upper shaft section and a lower shaft section with a threaded section, wherein the upper shaft section has a larger diameter than the lower shaft section and a corresponding screw system.

[0002] For joining building components, particularly round logs for the exterior walls of a log house, it is known to connect the individual logs with long wood screws. The wood screws used for this purpose have an upper, unthreaded shank section at least as long as the lower, threaded shank section. In normal use, the lower shank section with the threaded section is screwed completely into a lower log, while the upper, unthreaded shank section is inserted into the upper log. The reason for the screw passing through the upper log without a threaded section is that, as a natural material, logs are subject to seasonal volume fluctuations. Moisture in autumn causes the logs to swell, and dryness in summer causes them to shrink.The logs of a log house wall expand and contract with the seasons. If these logs are joined with long threaded bolts, the bolts often break because the forces exerted by the logs' deformation are considerable. This deformation problem is far less pronounced in interior log walls, as a house maintains a constant internal humidity and temperature throughout its lifespan. The logs of an interior wall therefore experience significantly less volume change.

[0003] To compensate for the seasonal deformation of structural elements, in this case round beams, a screw system is known from EP 3 995 704 B1, in which an upper shank section of the screw is enclosed by a frustoconical coil spring. The uppermost round beam has a blind hole, at the bottom of which a smaller diameter hole is drilled. The screw described therein is inserted through this smaller hole in the upper round beam and screwed into the lower round beam. The screw compresses the frustoconical coil spring, which rests on the bottom of the blind hole in the upper round beam. This elastically couples the two round beams. The round beams can expand or contract in the opposite direction to the force of the coil spring without damaging the connection.It has been shown that roof trusses whose beams are connected using this system can even withstand earthquakes without damage. Two identical houses were observed to react very differently during an earthquake. One house had a conventional roof structure, while the other, an adjacent house, had a roof constructed using this screw system. While the roof truss with the conventional design collapsed due to the earthquake's vibrations, the roof truss with the aforementioned screw system appeared to absorb the vibrations and, outwardly, to have survived without damage. This screw system has since proven its worth in numerous constructions.The screw system described above has the disadvantage that its use requires not only a blind hole to be drilled into the upper log, within which the frustoconical coil spring can act, but also a second hole for the unthreaded shank of the screw. Finally, another hole must be drilled centrally into the bottom of the blind hole. This slows down the construction of a log house, which is actually intended to be a quick process.

[0004] The object of the invention is therefore to provide a screw system for round logs of the exterior wall of a log house and also for logs of the interior walls of a house, which is easier to handle. The object of the invention is achieved by a screw with the features of claim 1. These screws are suitable for use with less flexible building elements, in this case logs. Further advantageous embodiments are specified in the dependent claims to claim 1. A screw system with the features of claims 6 to 10, comprising the screw of claims 1 to 10, can be used for flexible round logs for the exterior walls of a house.

[0005] According to the concept of the screw according to the invention, the screw has an upper shank section with a larger diameter than a lower shank section with a threaded section. A milling section is provided between the upper and lower shank sections, the milling section having a larger effective cutting diameter than the diameter of the upper shank section. The effect of the milling section is that, when the screw is inserted, it creates the additional, smaller bore at the bottom of the blind hole. Since the milling section has a larger effective cutting diameter than the upper shank section, the bore created by the milling section when the screw is tightened is large enough to accommodate the chips produced during milling in the annular space between the upper shank section and the bore diameter.Therefore, it is only necessary to insert a simple blind hole into the upper block plank or round plank.

[0006] Depending on the effective cutting diameter of the milling section, more or fewer chips are produced during milling. To remove excessive chips, the upper shank section can be designed with at least one spiral chip removal structure. This chip removal structure can be constructed like a wood drill bit. The upper shank section has deep, spiral grooves extending to the center of the shank, which, when screwed in, transport the chips out of the screw and milling hole through the rotational movement. The chip removal mechanism is identical to that of a wood drill bit. However, depending on the expected chip volume, the spiral chip removal structure can also be implemented with finer grooves, where the grooves only extend 5% to 10% of the shank diameter into the shank. The number of groove turns can range from 0.75 to 3 along the entire length of the upper shank section.

[0007] Since the screws described here are high-load-bearing connecting screws, their diameters are correspondingly large. The screws typically have a length between 20 cm and 30 cm, even up to 50 cm, and an upper shank width between 8 mm and 16 mm. To cut the volume of the screw in the lower board, the screw tip may be designed with a cutting notch. This notch can cut into the material, and the chips can be conveyed by the pressure in the screw channel to the milling section.

[0008] The torque of these high-load-bearing screws necessitates a correspondingly robust drive mechanism in the screw head. Instead of a simple external hex drive, which is typically used on a construction site with an impact wrench and a socket to drive the screw, a dual drive can be employed. This dual drive on the screw head features, for example, a polygonal drive on the outside of the head and a central internal drive. This allows for the combination of an external hex, triangular, or square drive with an Allen or Torx drive. External Torx drives are also possible. The dual drive enables a higher torque to be applied to the screw. When using lighter wood, such as spruce, a single drive can be used instead, such as a powerful cordless screwdriver with an Allen or Torx key.For heavier woods, such as tropical wood or oak, it may be necessary to use the double drive.

[0009] To better distribute the force of the screw onto the upper structural element, such as a block or round beam, the screw head can be designed with a lower flange. This flange has a greater maximum radial extent than the outermost points of the polygon. The force of the screw is thus distributed, preventing local material overload.

[0010] The screw described so far is ideally suited for connecting plank elements that are not subject to significant movement. For round planks that are subject to considerable movement, such as those used for the exterior walls of a log house, a screw system featuring the aforementioned screw is recommended. This screw system includes a frustoconical coil spring in addition to the screw. This spring sits in a blind hole in the upper structural element to achieve the effect described earlier. In the screw system combination presented here, it is sufficient to drill the blind hole in the upper structural element, into which the frustoconical coil spring is inserted. To insert the screw, simply screw it into the bottom of the blind hole in the upper structural element.The milling section then cuts the diameter in the upper component, so that there is no threaded connection or tight-fitting shank-bore connection, which can develop a potentially strong adhesion as the screw ages. The frustoconical coil spring has an internal extension area at its end coil facing the smaller end face of the cone. This extension area is dimensioned such that the upper shank section of the screw is enclosed by the frustoconical coil spring, and that the flange formed at the screw head of the frustoconical coil spring provides an axial holding or supporting effect against the screw-in direction at its smaller end face. The spring constant of the frustoconical coil spring is between 500 N / cm and 5,000 N / cm, depending on the round beam diameter.

[0011] To better distribute the force transmission of the coil spring to the bottom of the blind bore, a disc serving as a pressure or support element may be provided, which rests on the larger end face of the frustoconical coil spring at its end coil, and in the assembled state is arranged between a surface of the element to be connected to the screw system and the frustoconical coil spring in order to distribute the force introduced by the frustoconical coil spring over a larger area.

[0012] It has been observed that when using the screw system presented here, the screw is often driven so far into the component by impact drivers or powerful cordless screwdrivers that the frustoconical coil spring is compressed beyond a permissible limit, exceeding its elastic range. As a result, the frustoconical coil spring undergoes plastic deformation, thus reducing its restoring force. In extreme cases, it has also been observed that the screw is driven in so far that the frustoconical coil spring is completely compressed until the coils collide. When the coils collide, the spring can only expand, not compress further. Consequently, the screw system lacks the necessary compression travel to compensate for volume changes.To prevent such misuse, a device can be provided to limit the maximum compression of the screw during tightening. This can be achieved by a spacer sleeve enclosing the upper shank section of the screw and positioned within the frustoconical coil spring. The spacer sleeve rests on the disc that abuts the larger end face of the coil spring, limiting the compression of the coil spring to the length of the spacer sleeve. If the spacer sleeve is very thick, maximum compression is prevented, so that the frustoconical coil spring is only deformed within its elastic range. The user will feel the rather harsh stop in the tool, impact wrench, or cordless screwdriver and will turn the screw back slightly, allowing the frustoconical coil spring to move in both directions.It is also possible to dimension the spacer sleeve so that it collapses under the force that occurs when the volume of the components to be connected changes, thus restoring the degree of freedom to the frustoconical spiral spring.

[0013] In a further embodiment of the invention, the disc may have a raised area in a central region supporting the spacer sleeve, upon which the spacer sleeve is supported, so that the spacer sleeve is raised relative to the base of the disc. This raised area can serve to release the spring travel if the raised area collapses intentionally instead of the sleeve. Furthermore, the raised area in the central region directs the forces of the screw system into the component further away from the bore, where the material is less likely to break out than directly at the bore wall.

[0014] The invention is explained in more detail with reference to the following figures.

[0015] It shows: Fig. 1 a screw according to the invention in a first embodiment, Fig. 2 the screw out Fig. 1 in use, shown in a cross-sectional drawing through two connected components, Fig. 3 a screw according to the invention in a second embodiment, Fig. 4 a screw according to the invention in a third embodiment, Fig. 5 a screw according to the invention in a fourth embodiment, Fig. 6 a screw according to the invention in a fifth embodiment, Fig. 7 comprising a screw system according to the invention, the aforementioned screw, Fig. 8 the screw system from Fig. 7 in use, shown in a cross-sectional drawing through two connected components,

[0016] in Fig. Figure 1 shows a screw 100a according to the invention in a first embodiment. The screw 100a has an upper shank section 110 and a lower shank section 120. The upper shank section 110 has a larger diameter d1 than the diameter d2 of the lower shank section d2. A milling section 130 is provided between the upper shank section 110 and the lower shank section 120. The milling section 130 has a larger effective cutting diameter d3 than the diameter d1 of the upper shank section 110. When the screw 100a is screwed in, chips are conveyed from the milling section 130 into the annular space between the upper shank section 110 and the upper bore OB, which is enlarged by the milling section 130. The upper shank section 110 does not make contact with the upper component B1 when the screw 100a is screwed in. The milling section 130 shown here consists of a conical cutting milling cutter with vertical cutting blades.In this embodiment, the conical cutting edge serves as a connection between the two shank sections 110, 120 of the screw 100a. Since the conical cutting edge can be hardened, this prevents the screw 100a from breaking at the connection between the upper shank section 110 and the lower shank section 120 under heavy load. In this embodiment, the screw head 160 has a combined drive geometry with an outer polygon 162, here in the form of an M-hex, and a central internal drive 164. An arrow A is shown above the screw 100a, pointing down at the screw head 160. This view is shown in the two alternatives A to the left of the screw 100a. The upper alternative of the screw head 160 has a combined double drive consisting of an M-hex on the outside and an internal hexagon (Allen key) on the inside.The lower alternative of the screw head 160 has a dual drive consisting of an M-hex socket on the outside and a star-shaped recess on the inside, similar to a Torx drive. The screw head 160 has a lower flange 170, the flange 170 having a larger maximum radial extent than the outermost corners of the polygon 162. To cut a threaded hole and prevent cracking in a wooden plank, this embodiment of the screw 100a has a cutting notch 150 at the screw tip 102.

[0017] Fig. 2 shows the screw from Fig. Figure 1 shows the assembly in use, depicted in a sectional drawing through two connected components: an upper component B1 and a lower component B2, as is typical when joining two log planks. The upper component B1 has a blind hole SB, within which the screw head 160 is countersunk. The screw head 160, with its flange 170, rests on the bottom of the blind hole SB and secures the upper component B1. The milled section 130 has worked its way into the lower component B2 and sits as a plug in the threaded bore GB formed by the threaded section 125. Behind it, the milled section 130 has left an upper bore OB with a larger diameter, namely diameter d3 of the milled section, in which the upper shank section 110 of the screw 100a, with diameter d1, is arranged and has no direct contact with the component B1.The annular space between the upper bore OB and the upper shaft section 110 contains chips that were produced by the milling section 130.

[0018] In Fig. Figure 3 shows a screw 100b according to the invention in a second embodiment. This embodiment differs from the embodiment of screw 100a in the figures. Fig. 1 and Fig. 2 by a spiral chip conveying structure 140 in the upper shank section 110. The spiral chip conveying structure 140 shown here is reminiscent of the spiral grooves in a wood drill bit, with the difference that the entry edges are not sharpened and do not have a special cutting edge. The similarity of the spiral chip conveying structure 140 shown here to a wood drill bit demonstrates the chip-conveying effect.

[0019] In Fig. Figure 4 shows a screw 100c according to the invention in a third embodiment. This embodiment differs from embodiment 100b in that Fig. 2 of the first embodiment in the figures Fig. 1 and Fig. 2 by a similarly spiral chip conveying structure 142, the grooves of which, however, extend much less into the upper shaft section 110. Specifically, they extend a maximum of 5% to 10% into the diameter d1 of the upper shaft section. The number of turns of the spiral chip conveying structure 142 comprises approximately 1.5 revolutions over the entire upper shaft section 110, whereby the number of turns can vary between 0.75 and 3.

[0020] Fig. Figure 5 shows a screw 100d according to the invention in a fourth embodiment. This embodiment differs from the embodiment of screw 100c in Fig. 3 by a barrel-shaped milled section 131. This sits slightly lower than the conical milled section 130 in the figures. Fig. 1, Fig. 2 and Fig. 3. Between the barrel-shaped milling section 131 and the upper shaft section 110 is a lumen created by the taper at the lower end of the upper shaft section 110. This lumen, which forms between the screw 100d and components B1 and B2 when the screw is tightened, provides space to collect chips produced by the barrel-shaped milling section. The barrel-shaped milling section 131 differs from the conical milling section 130 shown in the figures. Fig. 1, Fig. 2, Fig. 3 and Fig. Four notches, the edges of which are sharpened.

[0021] Fig. Figure 6 sketches a screw 100e according to the invention in a fifth embodiment. This embodiment differs from the embodiment of screw 100d in Fig. 4 by a spherical milling section 132. The spherical milling section 132 is better suited for harder types of wood, whereas the barrel-shaped milling section is more suitable for softer and fibrous types of wood.

[0022] Fig. Figure 7 shows a screw system 180 according to the invention comprising the aforementioned screw in embodiment 100a in the figures Fig. 1 and Fig. 2. In addition to the screw 100a, the screw system 180 has a frustoconical coil spring 200. The frustoconical coil spring 200 has an inner extension area 214 at its end coil 212 facing the smaller truncated cone face 210, which is dimensioned such that the upper shaft section 110 of the screw 100a is enclosed by the frustoconical coil spring 200. The flange 170 formed on the screw head 160 provides the frustoconical coil spring 200 with an axial holding or supporting effect at its smaller truncated cone face 210 in the screwing direction. In this embodiment of the screw system 180, an optional spacer sleeve 400 is provided, which prevents the frustoconical coil spring 200 from being compressed beyond a maximum degree when the screw 100a is screwed in, at which point the frustoconical coil spring 200 would be plastically deformed.

[0023] Furthermore, in this embodiment, a disc 300 serving as a pressure or support element is provided, which rests against the larger truncated conical face 220 of the frustoconical coil spring 200 at its end coil 222 and, in the assembled state, is arranged between a surface of the element to be connected with the screw system 180 and the frustoconical coil spring 200 in order to distribute the force introduced by the frustoconical coil spring 200 into the element to be connected over a larger area. It is possible that the disc 300 has a raised portion 310 or 311 in a central area supporting the spacer sleeve 400, on which the spacer sleeve 400 is supported, so that the spacer sleeve 400 is raised relative to the base of the disc 300. This increase 310 or 311 can, on the one hand, increase the stability of the disc 300 against a force acting vertically on it through the spacer sleeve 400.However, it is also possible to design the riser 310, 311 in such a way that, should the spacer sleeve 400 act as a spacer, it collapses under the force of the elements to be joined in order to give the frustoconical spiral spring 200 room to compress further.

[0024] Fig. Figure 8 shows the screw system 180. Fig.Figure 7 shows the assembly in use, illustrated in a sectional drawing through two connected components, namely an upper component B3 and a lower component B4, as is typical when joining two round beams. The upper component B3 has a blind bore SB, within which part of the upper shank section 110 of the screw 100a is countersunk together with the frustoconical coil spring 200. The screw head 160 with the flange 170 rests on the frustoconical coil spring 200 at its smaller conical end face 210, and the frustoconical coil spring 200 provides an axial holding or supporting effect against the screwing direction. The washer 300 rests on the bottom of the blind bore SB. The screw 100a holds the upper component B3 securely via the frustoconical coil spring 200 and the washer 300.The milling section 130 has worked its way into the lower component B4 and is now plugged in the threaded bore GB formed by the threaded section 125. Behind it, the milling section 130 has left an upper bore OB with a larger diameter, namely diameter d3 of the milling section, in which the upper shank section 110 of the screw 100a is located and has no direct contact with the component. The annular space between the upper bore OB and the upper shank section 110 contains chips produced by the milling section 130.

[0025] The embodiments of the milling section 130, 131 and 132, the various embodiments of the spiral chip conveying structure 140, 141, the structure of the disc 300 with the optional elevations 310, 311, as well as the structure of the double drive, combination of the polygon 162 and the internal drive 164 and the optional cutting notch 150 can be used in any combination in the screws. REFERENCE MARK LIST 100a screw 100b screw 100c screw 100d screw 100 screws 102 screw tip 110 upper shaft section 120 lower shaft section 125 thread section 130 milling section, conical 131 Milling section, barrel-shaped 132 Milling section, spherical 140 chip conveyor structure 141 Chip conveyor structure 150 cutting notch 160 screw heads 162 Polygon 164 Internal drive 170 flange 180 screw system 200 spiral springs 210 smaller truncated cone face 212 End turn 214 Internal extent area 220 larger conical face 222 End turn 300 disc 310 increase 311 Increase 400 spacer sleeve B1 component B2 component B3 component B4 component d1 diameter d2 diameter d3 cutting diameter SB blind hole QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 3 995 704 B1

[0003]

Claims

[1] screw (100a, 100b, 100c, 100d, 100e) comprising - an upper shaft section (110) and - a lower shaft section (120) with a threaded section (125), wherein the upper shaft section (110) has a larger diameter (d1) than the diameter (d2) of the lower shaft section (120), characterized by , that a milling section (130, 131, 132) is provided between the upper shank section (110) and the lower shank section (120), wherein the milling section (130, 131, 132) has a larger effective cutting diameter (d3) than the diameter (d1) of the upper shank section (110). [2] Screw according to claim 1, characterized by , that the upper shaft section (110) has at least one spiral chip conveying structure (140, 141). [3] Screw according to one of claims 1 or 2, characterized by that the screw tip (102) has a cutting notch (150). [4] Screw according to any one of claims 1 to 3, characterized by , that the screw head (160) has a combined drive geometry with an external polygon (162) and a central internal drive (164). [5] Screw according to claim 4, characterized by , that the screw head (160) has a lower flange (170), wherein the flange (170) has a larger maximum radial extent value than the outermost corner points of the polygon (162). [6] having a screw system (180) - a screw (100a, 100b, 100c, 100d, 100e) according to claims 1 to 5, - a frustoconical spiral spring (200), characterized by , that the frustoconical spiral spring (200) has an inner extension area (214) at its end coil (212) facing the smaller truncated cone end face (210) which is dimensioned such that the upper shaft section (110) of the screw (100a, 100b, 100c, 100d, 100e) is enclosed by the frustoconical spiral spring (200), and that the flange (170) formed on the screw head (160) gives the frustoconical spiral spring (200) an axial holding or supporting effect in the screwing direction at its small frustoconical end face (210). [7] Screw system Claim 6, characterized by , that a disc (300) serving as a pressure or support element is provided, which rests on the larger truncated cone face (220) of the truncated cone-shaped spiral spring (200) at its end coil (222) and in the assembled state between a surface of the element to be connected with the screw system and the frustoconical coil spring (200) in order to distribute the force introduced by the frustoconical coil spring (200) over a larger area. [8] Screw system according to claim 6 or 7, characterized by , that the spring constant of the frustoconical spiral spring (200) is between 500 N / cm and 5,000 N / cm. [9] Screw system according to claim 7 or 8 referring back to claim 7, characterized by , that a spacer sleeve (400) encloses the upper shaft section (110) of the screw (100) and is arranged within the frustoconical spiral spring (200), wherein the spacer sleeve (400) rests on the disk (300) which abuts the larger conical truncated end face (220) of the coil spring (200) and limits the compression of the coil spring (200) to the length of the spacer sleeve (400). [10] Screw system according to claims 7 and 9, characterized by , that the disk (300) has a raised area (310, 311) in a central area supporting the spacer sleeve (400), on which the spacer sleeve (400) is supported, so that the spacer sleeve (400) is raised relative to the base of the disk (300).

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