Two-piece high-strength screw

Abstract

High-strength screw (1), with a head (2) with a tool attack contour (4), a shaft (3) with a free end (5) pointing away from the head (2), wherein a threaded section (6) with a thread (7) is arranged on the shaft (3), wherein the thread (7) is designed as a metric ISO thread or inch thread, characterized in that the head (2) and the shaft (3) are designed as materially separate parts, the head (2) has a radially internally arranged coupling recess (8) with an axial force transmission element (9) and a torque transmission element (10), the shaft (3) has a coupling element (11) arranged radially outside on its outer circumference with an axial force transmission counter element (12) and a torque transmission counter element (13), the coupling element (11) engages in the coupling recess (8), the axial force transmission element (9) and the axial force transmission counter element (12) are designed and arranged in such a form-fitting manner that an axial translational movement of the head (2) relative to the shaft (3) in the direction away from the free end (5) of the shaft (3) is prevented, and the torque transmission element (10) and the torque transmission counter element (13) are designed and arranged in such a way as to interlock in such a way that a rotational movement of the head (2) relative to the shaft (3) in the tightening direction of the thread (7) is prevented, wherein the axial force transmission element (9) and the axial force transmission counter element (12) are conically shaped, and wherein the axial force transmission element (9) and the torque transmission element (10) are arranged axially offset along the shaft (3).

Description

TECHNICAL AREA OF INVENTION

[0001] The invention relates to a high-strength screw with a head having a tool engagement contour and a shank with a free end pointing away from the head. A threaded section is arranged on the shank, wherein the thread is designed as a metric ISO thread or an inch thread.

[0002] Screws of this type, with a metric ISO thread or imperial thread, are used to create screw connections with a corresponding internal thread in a nut or component with a threaded hole and are distinct from wood screws and other self-tapping universal screws. Due to their high strength, they are used particularly in specialized technical fields that require such strength – e.g., the automotive industry, the aerospace industry, and mechanical engineering – and are separate from the trades, DIY, and hobby sectors. STATE OF THE ART

[0003] A high-strength screw with a head having a tool-engaging contour and a shank with a free end pointing away from the head is known from European patent application EP 3 358 021 A1. A threaded section with a thread designed as a metric ISO thread is arranged on the shank.

[0004] AU 78401 / 91 A relates to a screwable element for arrangement on a screw element such as a screw head or a nut in order to be able to exert a predetermined torque on the screw.

[0005] DE 20 2008 016 456 U1 relates to a threaded bolt with a shaft that is at least partially threaded and a head area for introducing a torque, wherein the head area is designed in such a way that, at least in a first direction of rotation, a torque introduced into the head area can only be transferred to the shaft up to a defined upper limit.

[0006] Other screwable elements are also known from the documents US 2013 / 0 136 557 A1, DE 156 467 A, US 2006 / 0 024 142 A1, US 3 978 758 A, US 2 237 236 A or JP S59 - 121 514 U. TASK OF INVENTION

[0007] The invention is based on the objective of providing a high-strength screw that can be manufactured flexibly and economically. SOLUTION

[0008] The object of the invention is solved according to the invention with the features of the independent patent claims.

[0009] Further preferred embodiments of the invention can be found in the dependent claims. FURTHER STATE OF THE TECHNOLOGY

[0010] A screw composed of several separate parts is known from Chinese patent application CN 103 438 076 A. The first of these parts is the screw head. This head has a radially internally arranged coupling element that projects from its head bearing surface. The coupling element has an approximately star-shaped cross-section. The second of these parts is a shank section. This shank section has a coupling recess on its free end face facing the head, corresponding to the coupling element. The coupling recess is also radially internally arranged. To connect the head to the shank section, the coupling element is inserted into the coupling recess. A third of these parts is another shank section. In this way, screws of different lengths are assembled from the head and a varying number of shank sections.

[0011] A similarly constructed screw composed of several separate parts is known from Chinese patent application CN 103 438 072 A. In this case, the coupling recess is designed as a bore with an internal thread and the coupling element as a threaded section with an external thread, which is arranged in a region of the shaft with a reduced outer diameter. DESCRIPTION OF THE INVENTION

[0012] The invention relates to a high-strength screw with a head having a tool engagement contour and a shank with a free end pointing away from the head. A threaded section is arranged on the shank, the thread being a metric ISO thread or an inch thread. The head and the shank are formed as materially separate parts. The head has a radially internally arranged coupling recess with an axial force transmission element and a torque transmission element. The shank has a radially externally arranged coupling element on its outer circumference with an axial force transmission counter element and a torque transmission counter element. The coupling element engages in the coupling recess.The axial force transmission element and the axial force transmission counter-element are designed and arranged to interlock in such a way that axial translational movement of the head relative to the shank in the direction away from the free end of the shank is prevented. The torque transmission element and the torque transmission counter-element are designed and arranged to interlock in such a way that rotational movement of the head relative to the shank in the tightening direction of the thread is prevented.

[0013] It is also possible to use a forming process for the machine production of a high-strength screw, in particular the screw described above and / or below, from a head blank and a shaft blank, with the following steps: - Forming the head blank in a forming tool such that a screw head with a radially internally arranged coupling recess with an axial force transmission element and a torque transmission element is produced, - Threading the head onto a shaft blank using the coupling recess, - Forming a part of the shaft blank in a forming tool such that a shaft is produced with a coupling element arranged radially outside on its outer circumference, comprising an axial force transmission counter element and a torque transmission counter element, and - Joining the head and shaft by translationally shifting the head so that the coupling element engages in the coupling recess.

[0014] These process steps are carried out in the specified order. However, the step of threading the head onto the shaft blank can also be performed after the step of forming the shaft blank to create the coupling element. Furthermore, it is possible for additional steps to be performed between the process steps. Definitions

[0015] High-strength screw: In this application, a high-strength screw is defined as a screw with a tensile strength R m of at least 800 N / mm 2 Understood. Typical high-strength screws belong to strength classes 8.8, 10.9, or 12.9. However, the high-strength screw according to the invention can also be an ultra-high-strength screw with a tensile strength R m of at least 1,400 N / mm 2 The inventive “high-strength” screw is therefore at least a high-strength screw, but can also be an ultra-high-strength screw.

[0016] Tool engagement contour: A tool engagement contour of the head is understood to be a contour located on the head of the screw, against which an actuating tool engages to actuate the screw. The contour is formed by several functional surfaces, which usually connect to one another via corners or radii. In the field of the invention, a tool engagement contour is often referred to as a "force engagement".

[0017] Tool attack outer contour: A tool attack outer contour is a contour located radially outside the head of the screw, against which an actuating tool engages to actuate the screw. The contour is formed by several functional surfaces, which usually connect to one another via corners or radii. In the field of the invention, a tool attack outer contour is often referred to as an "external force attack".

[0018] Tool engagement inner contour: A tool engagement inner contour is a contour located radially inside the head of the screw, into which an actuating tool engages to actuate the screw. The contour is formed by several functional surfaces, which usually connect to one another via corners or radii. The tool engagement inner contour defines a central recess in the head of the screw in a radial direction. In the field of the invention, a tool engagement inner contour is often referred to as an "internal force engagement".

[0019] Polygon: In this application, a polygon is understood to be a design of a tool attack outer contour of the head of the screw and a torque transmission counter element of the shank of the screw ("external polygon") or a tool attack inner contour of the head of the screw and a torque transmission element of the head of the screw ("internal polygon"), in which the approximately straight functional surfaces of the subunits of the polygon connect to each other at a corner at an angle of 120° within the subunit.

[0020] Multi-tooth: In this application, a multi-tooth design is understood to be a design of a tool attack outer contour of the head of the screw and a torque transmission counter element of the shank of the screw ("external multi-tooth") or a tool attack inner contour of the head of the screw and a torque transmission element of the head of the screw ("internal multi-tooth"), in which the approximately straight functional surfaces of the subunits of the multi-tooth design connect to each other at a corner at an angle of 90° within the subunit.

[0021] Multi-round: In this application, a multi-round is understood to mean a design of a tool attack outer contour of the head of the screw and a torque transmission counter element of the shank of the screw ("outer multi-round") or a tool attack inner contour of the head of the screw and a torque transmission element of the head of the screw ("inner multi-round"), in which the rounded functional surfaces connect to each other via rounded corners.

[0022] Star: In this application, a star is understood to be a design of a torque transmission counter element of the shaft of the screw or of a torque transmission element of the head of the screw, in which the approximately straight functional surfaces of the subunits of the star connect to each other at an angle of 60° within the subunit via a corner.

[0023] Geometry type: In this application, a geometry type is understood to be the underlying geometric shape of the tool engagement contour, the torque transmission element, and the torque transmission counter-element. Typical geometry types are polygon, multi-tooth, and multi-round. No distinction is made between the outer and inner contours. This means, for example, that an outer polygon and an inner polygon belong to the same first geometry type, an outer multi-tooth and an inner multi-tooth to the same second geometry type, and an outer multi-round and an inner multi-round to the same third geometry type.

[0024] Materially separate parts: The head and the shank of the screw are designed as materially separate parts. In this application, this is understood to mean that they were manufactured as non-connected, non-monolithic, separate parts. However, in the finished position of the screw, the head and the shank are joined together. This connection was therefore only achieved after their separate manufacture. Further description

[0025] The new high-strength screw with a metric ISO thread or imperial thread is designed as a screw consisting of at least two parts: a head and a shank, which are joined together in a specific manner. The connection is not achieved via a thread or any other type of joint that can be arbitrarily removed. Instead, the connection is such that the head and shank can only be separated from each other by destructive means. The screw may also include other components.

[0026] With the new type of connection between the head and the shank of the screw, the following two technical aspects, among others, must be considered when tightening a screw connection: For the bolted joint to achieve the desired locking effect, a sufficiently large axial preload force must be applied via the head of the bolt – more precisely, via the bearing surface of the bolt head ("axial force transmission"). To achieve this preload force, the head and shank must be screwed together in the tightening direction of the thread. The required torque is applied by means of an actuating tool via the tool engagement contour of the head and transferred to the shank ("torque transmission"). However, since the head and shank are made of separate materials, movement of the head relative to the shank in the direction away from the free end of the shank must be prevented for this torque transmission to occur.

[0027] The new two-part, high-strength bolt features a coupling recess on the head and a corresponding coupling element on the shank to achieve both axial force and torque transmission. The coupling recess, in turn, incorporates an axial force transmission element and a torque transmission element. The shank coupling element includes a corresponding axial force transmission counter-element and a torque transmission counter-element. The axial force transmission element and the axial force transmission counter-element interact to achieve the required preload. This prevents movement of the bolt head away from the free end of the shank as soon as the axial force transmission element and the axial force transmission counter-element engage.The torque transmission element and the torque transmission counter-element work together in such a way that the desired torque is transferred from the head to the shaft, thus enabling the screw to be actuated. This applies at least in the tightening direction of the thread.

[0028] The screws can be comparatively thin and long. Such screws with a large length-to-thickness ratio (L / D) can only be produced at a relatively low cycle rate using state-of-the-art technology. This low cycle rate results from the fact that the screw, which is produced in a multi-stage press, must be ejected and inserted along its entire shank length in each stage of the press. Furthermore, quality problems arise in the production of such screws because the buckling stiffness of both the screw and the forming tool decreases with increasing screw length.

[0029] The new split-head screw design, consisting of a head and shank, now allows for the economical and high-quality production of high-strength screws even when the screw shank is comparatively thin and long. This new screw design is also applicable to other screw geometries.

[0030] The screw head is manufactured separately, so the long shank length has no negative impact on its production. Forming the shank to create the coupling element is achieved in a single-stage process, requiring significantly less material to be elastically deformed. This eliminates the problems of low cycle rates and insufficient buckling stiffness inherent in prior art. The screw length is not limited by the press's installation space. The cycle rate is independent of the screw length. The high-strength screws can be produced using pre-hardened material. This eliminates the need for subsequent tempering and straightening, further reducing manufacturing costs. The new two-part screw is suitable for standardization, thus reducing setup times.

[0031] The coupling recess can be stepped, comprising a first section with a first inner diameter and a second section with a second inner diameter. The first inner diameter is larger than the second. The second section is positioned closer to the free end of the shaft than the first. This makes the second section the axial force transmission element, acting as an axial stop. Beyond this axial stop, movement of the head towards the free end of the shaft is impossible. However, the head may be movable in the opposite direction, away from the stop. Such movement can also be prevented. This can be achieved, for example, by an undercut, an interference fit, crimping, or other elastic-plastic deformation.However, it is also possible that no such separate locking mechanism is implemented, but rather that this locking mechanism is provided by the threaded section.

[0032] The coupling element can form an axial counter-stop corresponding to the axial stop, the outer diameter of which is larger than the outer diameter of the shaft and larger than the second inner diameter of the coupling recess. In this way, the pair of stop and counter-stop prevents the axial translational movement of the head towards the free end of the shaft, which is necessary to apply the preload force.

[0033] The first section of the coupling recess can form the torque transmission element. However, it is also possible for the second section to form the torque transmission element. It is also possible for both sections to form the torque transmission element. These two sections do not necessarily have to be directly adjacent to each other. Other sections can be positioned between them, fulfilling different functions or no functions at all.

[0034] The torque transmission element and the torque transmission counter-element can be designed and arranged to interlock in a form-fit manner. Such a form fit can be achieved, in particular, by having the torque transmission element and the torque transmission counter-element of the polygonal, multi-tooth, multi-round, or star geometry type. However, other geometric designs that provide the desired form fit are also possible. A knurled edge is one example. It is also possible to choose a different type of torque transmission. One possibility according to the invention is a friction-fit connection. This can be implemented, in particular, as an interference fit.

[0035] The torque transmission element and the torque transmission counter-element can be designed and arranged in such a way that even a rotational movement of the head relative to the shaft in the loosening direction of the thread is prevented. This is the normal case, in which the screw can be operated equally in both directions of rotation without restrictions.

[0036] The torque transmission element and the torque transmission counter-element can each be designed symmetrically in the circumferential direction. This symmetry means that the torque transmission element and torque counter-transmission element are designed in such a way that – apart from the fact that one direction of rotation loosens and the other tightens the screw connection – they function in the same way regardless of the direction of rotation.

[0037] The torque transmission element and the torque transmission counter-element can also each be designed asymmetrically in the circumferential direction. This allows for different interactions depending on the direction of rotation. For example, the asymmetry can be designed such that rotational movement of the head relative to the shank in the loosening direction of the thread is not prevented. This results in a secure screw connection that cannot be loosened, or at least not without additional measures, by unauthorized persons.

[0038] The torque transmission element and the torque transmission counter-element can be designed such that they determine the maximum tightening torque of the screw and, if the maximum tightening torque is exceeded, no longer prevent the rotational movement of the head relative to the shank in the tightening direction of the thread. In this way, the screw itself provides a torque limiter. This prevents the tightening of a screw connection beyond the maximum tightening torque.

[0039] The shank of the screw can be made of high-strength steel or a fiber-reinforced composite material (e.g., CFRP). The head of the screw can also be made of high-strength steel or a fiber-reinforced composite material (e.g., CFRP). Due to the two-part design of the screw, many different material pairings are possible, as long as the strength requirements for a high-strength screw are met. The choice of material can also be influenced by assigning specific electrically conductive or insulating properties to the head and shank. For example, metal, especially steel, can be encased in an insulating plastic sheath. Thus, the head of the screw can be electrically conductive and the shank electrically non-conductive. The reverse configuration is also possible.

[0040] The new process is used to manufacture a high-strength screw, as described above. In all process steps described above, the screw can still exhibit one or more of the characteristics described above.

[0041] Before threading the head onto the shaft blank using the coupling recess, the head blank can be formed in a forming tool to create a tool engagement contour. This tool engagement contour can be an external or internal contour and can be of the polygonal, multi-tooth, or multi-round geometry type.

[0042] After joining the head and shank, the head can be secured to the shank to prevent axial translational movement relative to the shank towards the free end. This securing can be achieved, for example, by an undercut, an interference fit, riveting, or other elastic-plastic deformation. However, it is also possible that no such separate securing mechanism is implemented, and that this securing is provided by the threaded section itself.

[0043] The forming process for the machine-based, chipless production of the high-strength screw is primarily a cold forming process. The process is carried out using a forming tool in a forming press, particularly a multi-stage press. The shank blank can be held in the forming press by clamping jaws during the forming of its axial end region. The forming of the axial end region of the shank blank can be performed using a translationally moving punch.

[0044] To achieve the high strength of the screw, it can undergo heat treatment during its manufacture. This heat treatment can, in particular, involve bainitic tempering (intermediate heat treatment) to create a bainite microstructure.

[0045] The forming process for producing the threaded section can involve, in particular, rolling or roller forming. It can also involve, in particular, cold forming.

[0046] The starting material used to manufacture the high-strength screw is commonly referred to as "wire". The wire used for the new high-strength screw can consist of cold-formable, untreated steel and have a carbon content of approximately 0.2% to 0.6% or approximately 0.2% to 0.5%. The steel may contain alloying elements, in particular Cr, Mo, Mn, Ni, V, Nb, or Ti, in particular totals exceeding approximately 1.1%.

[0047] The new high-strength screw can have a bainite microstructure, which is produced, in particular, at least partially by bainitic hardening. The bainite microstructure results in very high tensile strength combined with very high ductility. This high ductility, or toughness, distinguishes the bainite microstructure significantly from a martensitic microstructure, which, in the prior art, is produced by hardening followed by tempering. In the intermediate-stage tempering process, hardening is achieved instead by rapid cooling from the austenite phase through an isothermal microstructure transformation in the bainite stage. The part, especially the screw, remains in a salt bath at an isothermal temperature until the microstructure transformation from austenite to bainite is complete across the entire cross-section. The tempering process required for martensitic hardening can preferably be omitted. This also reduces the tendency for distortion due to hardening.

[0048] Advantageous further developments of the invention are evident from the claims, the description, and the drawings. The advantages of features and combinations of features mentioned in the description are merely examples and can have an effect alternatively or cumulatively, without necessarily requiring that the advantages be achieved by embodiments of the invention. Without thereby altering the subject matter of the attached claims, the following applies with regard to the disclosure content of the original application documents and the patent: further features can be seen from the drawings—in particular, the geometries and relative dimensions of several components to one another, as well as their relative arrangement and functional connection.The combination of features from different embodiments of the invention or from features of different claims is also possible, deviating from the chosen cross-references in the claims, and is hereby encouraged. This also applies to features that are illustrated in separate drawings or mentioned in their description. These features can also be combined with features from different claims. Likewise, features listed in the claims can be omitted for further embodiments of the invention.

[0049] The features mentioned in the patent claims and the description are to be understood, with regard to their number, as meaning that exactly that number or a greater number than the stated number is present, without the need for the explicit use of the adverb "at least". Thus, for example, if a thread is mentioned, this is to be understood as meaning that exactly one thread, two threads, or more threads are present. These features may be supplemented by other features or may be the only features that comprise the respective product.

[0050] The reference numerals contained in the patent claims do not constitute a limitation of the scope of the subject matter protected by the patent claims. They merely serve the purpose of making the patent claims easier to understand. BRIEF DESCRIPTION OF THE FIGURES

[0051] The invention will now be further explained and described with reference to preferred embodiments shown in the figures. Fig. Figure 1 shows a perspective view of a first exemplary embodiment of the new high-strength screw. Fig. Figure 2 shows an enlarged perspective view of part of the screw according to Fig. 1. Fig. Figure 3 shows a partially cropped perspective view of the screw according to Fig. 2. Fig. Figure 4 shows a sectional view of part of the screw according to Fig. 1. Fig. Figure 5 shows a sectional view of a second exemplary embodiment of the new screw. Fig. Figure 6 shows a sectional view of a third exemplary embodiment of the new screw. Fig. Figure 7 shows a perspective view of another embodiment of the new screw. Fig. Figure 8 shows a partially cropped perspective view of the screw according to Fig. 7. Fig. Figure 9 shows a perspective view of part of a first embodiment of the coupling element of the shaft of the new screw. Fig. Figure 10 shows a perspective view of part of a second embodiment of the coupling element of the shaft of the new screw. Fig. Figure 11 shows a perspective view of part of a third embodiment of the coupling element of the shaft of the new screw. Fig. Figure 12 shows a perspective view of part of a fourth embodiment of the coupling element of the shaft of the new screw. Fig. Figure 13 shows a perspective view of part of a fifth embodiment of the coupling element of the shaft of the new screw. Fig. Figure 14 shows a perspective view of part of a sixth embodiment of the coupling element of the shaft of the new screw. Fig. Figure 15 shows a view of a first exemplary embodiment of the head of the new screw with a coupling recess. Fig. Figure 16 shows a view of a second exemplary embodiment of the head of the new screw with a coupling recess. Fig. Figure 17 shows a view of a third exemplary embodiment of the head of the new screw with a coupling recess. Fig. Figure 18 shows a view of a fourth exemplary embodiment of the head of the new screw with a coupling recess. Fig. Figure 19 shows a view of a fifth exemplary embodiment of the head of the new screw with a coupling recess. Fig. Figure 20 shows a view of a sixth exemplary embodiment of the head of the new screw with a coupling recess. Fig. Figure 21 shows a partially cropped perspective view of another exemplary embodiment of the new screw. Fig. 22 shows another view of the screw according to Fig. 21. Fig. Figure 23 shows a perspective view of another exemplary embodiment of the new screw. Fig. Figure 24 shows a partially cropped perspective view of the screw according to Fig. 23. Fig. Figure 25 shows a perspective view of another exemplary embodiment of the head of the new screw with a coupling recess. Fig. Figure 26 shows a lateral sectional view of the screw head according to Fig. 25. Fig. Figure 27 shows another view of the head of the screw according to Fig. 25. Fig. Figure 28 shows a perspective view of an exemplary embodiment of the shaft of the new screw, which corresponds to the head according to Fig. 25-27 belongs. Fig. Figure 29 shows a side view of the shaft according to Fig. 28. Fig. Figure 30A shows a first step of an exemplary embodiment of the new method for manufacturing the new screw. Fig. Figure 30B shows a second step of the new procedure. Fig. Figure 30C shows a third step of the new procedure. Fig. Figure 30D shows a fourth step of the new process. Fig. Figure 30E shows a fifth step of the new procedure. FIGURE DESCRIPTION

[0052] Fig. Figures 1-4 show different views of a first exemplary embodiment of a new high-strength screw 1. The screw 1 is a high-strength screw 1 with a tensile strength of at least 800 N / mm². 2 , in particular an ultra-high-strength screw 1 with a tensile strength of at least 1400 N / mm² 2 The same applies to the other embodiments of screw 1.

[0053] The screw 1 has a head 2 and a shaft 3. The head 2 and the shaft 3 are designed as separate components, which were initially manufactured separately and only subsequently joined together.

[0054] The head 2 has a tool engagement contour 4, which serves to actuate the head in order to tighten or loosen a screw connection made with the screw 1. In this case, it is an external tool engagement contour. However, it could also be an internal tool engagement contour. Combinations of both contour types are also possible. In the example shown, the geometry of the tool engagement contour is a hexagon. Other geometry types are also possible.

[0055] The shaft 3 has a free end 5 extending away from the head 2. A threaded section 6 with a thread 7 is arranged on the shaft 3. In this case, it is located in the region of the free end 5. However, it could also be arranged at another location on the shaft 3, either alternatively or additionally. In the example shown, the thread 7 is a metric ISO thread. However, it could also be an inch thread.

[0056] The head 2 and the shank 3 of the screw 1 are designed as materially separate parts. For this purpose, the head 2 has a radially internally arranged coupling recess 8 with an axial force transmission element 9 and a torque transmission element 10. Correspondingly, the shank 3 has a radially externally arranged coupling element 11 on its outer circumference with an axial force transmission counter element 12 and a torque transmission counter element 13. The coupling element 11 engages in the coupling recess 8 to establish the connection between the head 2 and the shank 3.

[0057] The axial force transmission element 9 and the axial force transmission counter-element 12 are designed and arranged to interlock in such a way that axial translational movement of the head 2 relative to the shaft 3 in the direction away from the free end 5 of the shaft 3 is prevented. The torque transmission element 10 and the torque transmission counter-element 13 are designed and arranged to interlock in such a way that rotational movement of the head 2 relative to the shaft 3 in the tightening direction of the thread 7 is prevented. In this case, this interlocking is positive-locking. However, other types of torque transmission – e.g., frictional engagement – ​​are also possible.

[0058] The coupling recess 8 is stepped and has a first section 14 with a first inner diameter 15 and a second section 16 with a second inner diameter 17. The first inner diameter 15 is larger than the second inner diameter 17, with the second section 16 being located closer to the free end 5 of the shaft 3 than the first section 14. In this way, the second section 16 forms the axial transmission element 9 in the sense of an axial stop.

[0059] The coupling element 11 forms an axial counter-stop corresponding to the stop, the outer diameter of which is larger than the outer diameter of the shaft 3 and larger than the second inner diameter 17 of the coupling recess 8.

[0060] The first area 14 forms the torque transmission element 10. However, the torque transmission element 10 could also be formed additionally or alternatively by the second area 16 or another part.

[0061] In the present case, the torque transmission element 10 and the torque transmission counter element 13 belong to the polygonal geometry type, and in particular the hexagonal geometry type. However, other geometry types are also possible.

[0062] The torque transmission element 10 and the torque transmission counter-element 13 are designed and arranged to interlock in such a way that rotational movement of the head 2 relative to the shaft 3 in the loosening direction of the thread 7 is also prevented. In the present case, the torque transmission element 10 and the torque transmission counter-element 13 are each designed symmetrically in the circumferential direction. This ensures that the torque transmission occurs in the same way regardless of the direction of rotation. However, it is also possible for the torque transmission element 10 and the torque transmission counter-element 13 to each be designed asymmetrically in the circumferential direction. This is demonstrated by Fig. 25-29 below explained in more detail.

[0063] In the following descriptions of the further embodiments of the new screw 1, not everything that was stated with regard to the first exemplary embodiment of screw 1 according to [reference to relevant document] will be repeated in order to avoid unnecessary repetition. Fig. Sections 1-4 have been explained. Reference is made to these explanations in their entirety, unless the specific difference between the embodiments is being addressed.

[0064] In Fig. 5 is a Fig. Figure 4 shows a corresponding view of a second exemplary embodiment of the new screw 1. The coupling recess 8 and the coupling element 11 are designed differently here. The torque transmission element 10 is not located in the first region 14, but in the second region 16. The torque transmission thus takes place in the region of the end of the head 2 that points towards the free end 5 of the shaft 3.

[0065] A third exemplary embodiment of the new screw 1 is shown in Fig. Figure 6 shows that the head 2 can also have an axially longer collar 18. In this case, the torque transmission takes place mostly in the area of ​​the collar 18 of the head 2.

[0066] Fig. 7 and Fig. Figure 8 shows views of another exemplary embodiment of the new screw 1. In this case, the screw 1 has two threaded sections 6. The head 2 is arranged between these two threaded sections 6. Otherwise, the coupling recess 8 and the coupling element 11 are designed in the same way as in the first embodiment of the screw 1 described above.

[0067] Fig. Figures 9-14 show various examples of the design of the coupling element 11 of the shaft 3. Fig. 9 The torque transmission counter element 13 is designed as a hexagon. In Fig. 10 The torque transmission counter element 13 is designed as a different configuration with twelve functional surfaces. In Fig. The torque transmission counter-element 13 is designed as a twelve-sided shape. Fig. The torque transmission counter-element 13 is designed as a twelve-tooth tooth. Fig. The torque transmission counter-element 13 is designed as a twelve-point star. Fig. 14 the torque transmission counter element 13 is designed as a hexagonal round.

[0068] Fig. Figures 15-20 show different embodiments of the head 2 of the new screw 1. Fig. 15 The torque transmission element 10 of the coupling recess 8 of the head 2 is designed as a hexagon. In Fig. 16 is a twelve-pointed star. Fig. Number 17 refers to a twelve-tooth tooth. Fig. 18 is a dodecagon. In Fig. 19 is a different design with twelve functional areas. Fig. 20 is a six-rounder.

[0069] In Fig. 21 and Fig. Figure 22 shows an exemplary embodiment of the new screw 1, in which the torque transmission is realized not by a positive fit, but by a frictional fit. The coupling element 11 therefore has a certain interference with the coupling recess 8 and is inserted into the coupling recess 8 to achieve an interference fit.

[0070] Fig. 23 and Fig. Figure 24 shows another exemplary embodiment of the new screw 1. In this case, the tool engagement contour 4 of the screw 1 is designed as a tool engagement inner contour.

[0071] Fig. Figures 25-29 show various views of another exemplary embodiment of the new screw 1, specifically the head 2 and the shank 3. In this case, the torque transmission element 10 and the torque transmission counter-element 13 are each designed asymmetrically in the circumferential direction. The asymmetry is chosen such that the torque is reliably transmitted in the tightening direction of the thread 7, while such torque transmission is not possible in the loosening direction of the thread 7 due to the inclined surfaces of the torque transmission element 10.

[0072] Fig. Figures 30A-30E show, in a simplified representation, an exemplary forming process for the machine production of a high-strength screw 1 as described above. Fig. 30A shows a shaft blank 19. In Fig. In step 30B, a head 2 is threaded onto this shaft blank 19 by means of its coupling recess 8. This head 2 was previously produced from a head blank in a forming tool. However, the head 2 could also be threaded onto the shaft blank 19 or the shaft 3 in a later process step. Fig. At step 30C, the shaft blank 19 is held by means of clamping jaws 20 and, by means of a translationally moving punch 21, is formed in one piece so that the coupling element 11 is created. This is then in Fig. 30D representation. The shaft blank 19 thus became shaft 3. In Fig. 30E is now shown after joining head 2 and shaft 3 by translational displacement of head 2 in the area of ​​coupling element 11. REFERENCE MARK LIST 1 screw 2 heads 3 shaft 4 Tool attack contour 5 free ending 6 thread section 7 threads 8 coupling recess 9 Axial force transmission element 10 Torque transmission element 11 coupling element 12 Axial force transmission counter element 13 Torque transmission counter element 14 first area 15 first inner diameter 16 second area 17 second inner diameter 18th Federal State 19 shaft blanks 20 clamping jaws 21 stamps

Claims

[1] High-strength screw (1), with a head (2) with a tool attack contour (4), a shaft (3) with a free end (5) pointing away from the head (2), wherein a threaded section (6) with a thread (7) is arranged on the shaft (3), wherein the thread (7) is designed as a metric ISO thread or inch thread, characterized by , that the head (2) and the shaft (3) are designed as materially separate parts, the head (2) has a radially internally arranged coupling recess (8) with an axial force transmission element (9) and a torque transmission element (10), the shaft (3) has a coupling element (11) arranged radially outside on its outer circumference with an axial force transmission counter element (12) and a torque transmission counter element (13), the coupling element (11) engages in the coupling recess (8), the axial force transmission element (9) and the axial force transmission counter element (12) are designed and arranged in such a form-fitting manner that an axial translational movement of the head (2) relative to the shaft (3) in the direction away from the free end (5) of the shaft (3) is prevented, and the torque transmission element (10) and the torque transmission counter element (13) are designed and arranged in such a way as to interlock in such a way that a rotational movement of the head (2) relative to the shaft (3) in the tightening direction of the thread (7) is prevented, wherein the axial force transmission element (9) and the axial force transmission counter element (12) are conically shaped, and wherein the axial force transmission element (9) and the torque transmission element (10) are arranged axially offset along the shaft (3). [2] High-strength screw (1) according to claim 1, characterized by, that the coupling recess (8) is stepped and has a first area (14) with a first inner diameter (15) and a second area (16) with a second inner diameter (17), where the first inner diameter (15) is larger than the second inner diameter (17) and wherein the second area (16) is located closer to the free end (5) of the shaft (3) than the first area (14). [3] High-strength screw (1) according to claim 2, characterized by , that the second area (16) forms the axial force transmission element (9) in the sense of an axial stop. [4] High-strength screw (1) according to claim 3, characterized by , that the coupling element (11) forms an axial counter-stop corresponding to the axial stop, the outer diameter of which is larger than the outer diameter of the shaft (3) and larger than the second inner diameter (17) of the coupling recess (8). [5] High-strength screw (1) according to at least one of claims 2 to 4, characterized by , that the first area (14) forms the torque transmission element (10). [6] High-strength screw (1) according to at least one of claims 2 to 5, characterized by , that the second area (16) forms the torque transmission element (10). [7] High-strength screw (1) according to at least one of the preceding claims, characterized by , that the torque transmission element (10) and the torque transmission counter element (13) are designed and arranged to interlock in a form-fitting or friction-fitting manner. [8] High-strength screw (1) according to at least one of the preceding claims, characterized by , that the torque transmission element (10) and the torque transmission counter element (13) belong to the geometry type polygon, multi-tooth, multi-round or star. [9] High-strength screw (1) according to at least one of the preceding claims, characterized by, that the torque transmission element (10) and the torque transmission counter element (13) are designed and arranged in such a way as to interlock in such a way that a rotational movement of the head (2) relative to the shaft (3) in the loosening direction of the thread (7) is also prevented. [10] High-strength screw (1) according to at least one of the preceding claims, characterized by , that the torque transmission element (10) and the torque transmission counter element (13) are each symmetrically designed in the circumferential direction. [11] High-strength screw (1) according to at least one of claims 1 to 9, characterized by , that the torque transmission element (10) and the torque transmission counter element (13) are each designed asymmetrically in the circumferential direction. [12] High-strength screw (1) according to claim 11, characterized by, that the torque transmission element (10) and the torque transmission counter element (13) are designed and arranged in such a way that a rotational movement of the head (2) relative to the shaft (3) in the loosening direction of the thread (7) is not prevented. [13] High-strength screw (1) according to at least one of the preceding claims, characterized by , that the torque transmission element (10) and the torque transmission counter element (13) are designed in such a way that they determine the maximum tightening torque of the screw (1) and, if the maximum tightening torque is exceeded, no longer prevent the rotational movement of the head (2) relative to the shaft (3) in the tightening direction of the thread (7). [14] High-strength screw (1) according to at least one of the preceding claims, characterized by, that the shaft (3) is made of high-strength steel or a fiber composite material, and the head (2) is made of high-strength steel or a fiber composite material.

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