Blind rivet

Abstract

The invention relates to a blind rivet comprising a hollow rivet (2) and a rivet mandrel (5) guided in the hollow rivet (2), wherein the hollow rivet (2) has a setting head (3) with a setting head opening (30) and a hollow rivet shaft (4) adjoining the setting head (3), and wherein the rivet mandrel (5) has a mandrel head (6), a mandrel head shaft (60), a pull mandrel (7) and a locking region (8) formed between the rivet mandrel head shaft (60) and the pull mandrel (7). The pull mandrel (7) is guided in the setting head opening (30) so as to be axially movable. When an axial tensile force (Z) is exerted on the pull mandrel (7), the rivet mandrel head shaft (60) can be retracted into a shaft region (31) of the hollow rivet (2) under cold deformation until the locking region (8) is positioned on and / or in the setting head (3). The hollow rivet (2) has a forming region (32) for forming a closing head (33), wherein a forming stiffness of the forming region (32) is less than a forming stiffness of the shaft region (31). The rivet mandrel head (6) has a rivet mandrel head flange (61) which protrudes radially outwards from the rivet mandrel head shaft (60) by means of a rivet mandrel head shoulder (62) and engages on an open end face (63) of the forming region (32) of the hollow rivet shaft (4) during an axial movement of the rivet mandrel (5) in order to form the closing head (33) by forming the forming region (32).

Description

[0001] Blind rivet

[0002] The invention relates to a blind rivet comprising a hollow rivet and a rivet head guided within the hollow rivet. The hollow rivet has a setting head with an axial setting head opening and a hollow rivet shank extending axially from the setting head. The rivet mandrel has a rivet head, a rivet head shank extending axially from the rivet head, an axially extending draw mandrel (which is also referred to synonymously as rivet head shank in this text), and a locking area formed between the rivet head shank and the draw mandrel. The draw mandrel is guided axially movably within the setting head opening, and the setting head and the rivet head are arranged axially on opposite sides of the hollow rivet shank.

[0003] The head diameter of the rivet boss head is larger than the inner diameter in the shaft area of ​​the hollow rivet adjoining the setting head and is dimensioned such that, when an axial tensile force is applied to the draw mandrel, the rivet boss head can be drawn into the shaft area of ​​the hollow rivet under cold deformation of the shaft area and / or rivet boss head due to radial pressure until the locking area of ​​the rivet boss is positioned on or in the setting head of the hollow rivet.

[0004] Such a riveted joint is generally known from WO 2012 / 010858 A1 as a generic prior art. In this type of riveted joint, the fastener or joining material is held essentially by friction. This is sufficient for many riveted joints. However, in riveted joints subjected to high mechanical loads and / or vibrations, the joint can loosen or detach due to relative movement between the hollow rivet and the mandrel.

[0005] February 18, 2026 G 200 P 128 WO In the proposed blind rivet, the head shank diameter is an outer diameter of the rivet head shank. The head shank diameter is larger than the inner diameter of the shank section of the hollow rivet and smaller than the outer diameter of the shank section of the hollow rivet. The axial length of the rivet head shank is preferably greater than the axial length of the shank section of the hollow rivet shank. When the blind rivet is set, the rivet head shank is in every case, or at least in typical application situations, drawn into the shank section and projects out of the shank section into the forming area or the closing head formed by the forming area.

[0006] In typical applications of blind rivets, e.g., made of metallic materials (such as a rivet mandrel and a hollow rivet made of aluminum or aluminum alloys, with an outer diameter of the hollow rivet in the shank area between approximately 0.2 cm and 2.0 cm or between approximately 0.3 cm and 1.3 cm), the ratio of the difference between the outer diameter in the shank area and the inner diameter in the forming area, and the ratio of the difference between the outer diameter in the shank area and the inner diameter in the shank area, can be greater than 0.5, according to a preferred embodiment in the range of approximately 0.6 and 0.9, and particularly preferably in the range of approximately 0.7 and 0.8. In most applications, the wall thickness of the hollow rivet in the shank area should be reduced to at least half the initial wall thickness when the rivet mandrel head is drawn in.Otherwise, especially when used in components with high stiffness, the bearing pressure in the hole may be too high and the blind rivet may not be fully set because the rivet mandrel jams in the hollow rivet during setting and breaks off too early and / or at the wrong place (i.e., not at a defined predetermined breaking point).

[0007] It is generally known to those skilled in the art that the exact geometric relationships of these components depend on the strength of the materials used for the hollow rivet and the rivet mandrel, the tensile, holding and / or

[0008] February 18, 2026 G 200 P 128 WO The shear forces of the riveted joint and / or other properties of the riveted joint (e.g., the flow behavior of the materials under the setting forces, the tightness of the riveted joint to be achieved) depend on this. Based on the principles described here for riveted joints, the person skilled in the art will apply materials and dimensions of the individual components that are common and will select a suitable configuration for the intended application through testing.

[0009] Another type of rivet connection is known, for example, from EP 3315796 A1, in which the fastening or joining material is positively clamped between a setting head and a closing head formed by deformation opposite the setting head. In this case, there is no force-fit connection between the blind rivet and the fastening or joining material.

[0010] The purpose of the invention is to propose an improved blind rivet connection.

[0011] This problem is solved by a blind rivet with the features of claim 1. It is provided that the hollow rivet has a forming area on the side facing away from the setting head, adjacent to the shank area, for forming a locking head, wherein the forming stiffness of the forming area is less than the forming stiffness of the shank area. When a setting force is applied to the blind rivet, the forming area of ​​the hollow rivet deforms faster than the shank area of ​​the hollow rivet. This forms a locking head in the forming area. According to the invention, the different forming stiffness can be achieved in various ways, for example, by a thinner wall cross-section (wall thickness) of the hollow rivet in the forming area than in the shank area, by different heat treatment, and / or by work hardening.

[0012] February 18, 2026 G 200 P 128 WO According to a preferred embodiment of the invention, particularly to achieve a lower forming stiffness in the forming area than in the shank area, the inner diameter of the forming area can be larger than the inner diameter of the shank area. Preferably, the outer diameter of the hollow rivet shank in the forming area and in the shank area (within the limits of manufacturing tolerances, such as multi-stage pressing of the hollow rivet) is the same, possibly with the exception of defined or pronounced contours in the forming area and / or shank area. According to a preferred embodiment, the hollow rivet shank can have a cylindrical basic shape with a uniform outer diameter. This has the advantage that the hollow rivet can be easily inserted into openings in the joining or fastening material. The term "cylindrical basic shape" excludes the formation of embossings or other contours (such as ramps, knurling, and / or polygonal surface structures, e.g.,hexagonal or octagonal structures in the circumferential direction (e.g., as an anti-rotation feature) are incorporated. In the forming area of ​​the hollow rivet, suitable ramps can, for example, control and influence the formation of the rivet head, which may extend partially into the shank area of ​​the hollow rivet.

[0013] According to the invention, the wall thickness of the hollow rivet shank in the forming area can be smaller than the wall thickness of the hollow rivet shank in the shaft area. This facilitates the formation of the rivet head during the forming of the forming area. According to the invention, it can be advantageous if the inner diameter of the setting head opening is smaller than the inner diameter of the shaft area. This facilitates the guidance of the rivet boss in the hollow rivet. In this context, it can be provided according to the invention that the draw boss diameter corresponds to the inner diameter of the setting head opening. This automatically guides the rivet boss in the hollow rivet.

[0014] February 18, 2026 G 200 P 128 WOF. Furthermore, according to the invention, the rivet dome head has a rivet dome head flange at the end of the rivet dome head shaft facing away from the locking area. This flange projects radially outwards from the rivet dome head shaft with a rivet dome head shoulder and, in the event of axial movement of the rivet dome, engages an open end face of the forming area of ​​the hollow rivet shaft in order to form the locking head by deforming the forming area when a further tensile force is applied to the mandrel.

[0015] This clamps the material to be joined or fastened between the setting head of the hollow rivet and the closing head formed from the forming area of ​​the hollow rivet, and sets the hollow rivet in the material to be joined or fastened.

[0016] Preferably, the outer diameter of the rivet mandrel head flange is not larger than the outer diameter of the hollow rivet shank, or rather, than the outer diameter of the forming area and the shank area. According to a preferred embodiment of the invention, the outer diameter of the rivet mandrel head flange can be equal to the outer diameter of the hollow rivet shank, so that the blind rivet (hollow rivet and rivet mandrel together) can be easily inserted through an opening in the workpiece or fastener.

[0017] Before being set, the blind rivet is guided through an opening in the material to be joined or fastened, so that the rivet head rests against the material. According to the invention, the rivet head can be designed as a countersunk or flat head, depending on the type and / or properties of the material to be joined or fastened. Preferably, according to the invention, the outer diameter of the hollow rivet shank corresponds to the inner diameter of the opening in the material to be joined or fastened. This means that the hollow rivet shank can be inserted into the opening of the material to be joined or fastened with the necessary assembly clearance, but apart from this assembly clearance, rests essentially loosely against the inner circumference of the opening.

[0018] February 18, 2026 G 200 P 128 WO When setting the blind rivet, a tensile force Z is applied to the mandrel, and the setting head is supported by a counterforce G. This pulls the rivet head of the rivet boss towards the setting head. The rivet boss head shaft is thereby drawn into the shank area of ​​the hollow rivet and expands the shank area of ​​the hollow rivet radially outwards. To facilitate the insertion of the rivet boss head shaft into the shank area of ​​the hollow rivet, an insertion chamfer can be formed at the end of the rivet boss head shaft opposite the rivet boss head flange. This chamfer reduces the head shaft diameter, for example, to a locking head diameter. According to one embodiment, the locking head diameter can correspond to or be smaller than the inner diameter of the hollow rivet in the shank area.

[0019] As a result, the shank section is cold-formed and pressed against the inner wall of the opening in the workpiece or fastener. This creates a force-fit connection between the blind rivet and the workpiece or fastener. The workpiece or fastener is thus held firmly against the blind rivet. This force-fit connection, resulting from the radial expansion of the shank section, closes the opening in the workpiece or fastener (preferably even sealing it). In this shank section, the hollow rivet shank expands and presses against the outer surface of the opening in the workpiece or fastener. In the case of workpieces consisting of at least two separate materials joined by the blind rivet, this results in a force-fit connection between the workpieces.According to the invention, a defined bearing pressure and a particularly uniform circumferential contact of the hollow rivet shank are created in the outer area of ​​the shank within the opening (e.g., a bore) of the joining material (more than one material part) or fastening material (only one material part). This allows for high fatigue strength, high contact quality, and / or a seal. Furthermore, corrosion is prevented.

[0020] February 18, 2026 G 200 P 128 WO (crevice corrosion) in the opening of the joining or fastening material is prevented or reduced because there is a smaller open attack surface for chemically active media (including, for example, water or oxygen) on the hollow rivet,

[0021] For the sake of simplicity, the term "joining material" will be used below to refer to a single material component (essentially a fastening component) or multiple material components (joining material in the predefined sense), particularly when it is irrelevant to the type of riveted joint whether the blind rivet is fastened to one, two, or more materials. These applications are familiar to those skilled in the art.

[0022] As soon as the rivet head shoulder engages the open end face of the formed section of the hollow rivet shank during the pulling force applied to the mandrel, the formed section of the hollow rivet is folded radially away from the mandrel on a surface of the workpiece facing the rivet head, forming the closing head. The closing head is thus formed on the surface of the workpiece. In addition to the force-fit retention of the blind rivet in the opening of the workpiece, the workpiece is clamped between the setting head and the closing head, thereby also being held in a form-fit manner. According to the invention, this results in particularly high holding forces of the blind rivet and ensures a particularly secure riveted joint, namely both force-fit and form-fit.In one embodiment, the closing head can be provided with a comparatively large bearing surface on the side of the joining material facing the rivet head, the diameter of which preferably corresponds approximately to the largest diameter of the setting head. This ensures optimal distribution of forces and generates the lowest possible surface pressure on the material surface of the joining material. This can be advantageous or necessary for certain materials of the joining material, such as sensitive materials with carbon fibers like carbon fiber composites (CFRP). According to a preferred embodiment of this aspect of the invention, the diameter of the closing head (according to...) can be...

[0023] February 18, 2026 G 200 P 128 WOdem The setting of the blind rivet must correspond to at least approximately 0.7 times the largest diameter of the setting head.

[0024] According to a further embodiment of the invention, the locking area of ​​the rivet boss can have a locking head, wherein the locking head diameter is smaller than or approximately equal to the inner diameter in the shank area (and also larger than the inner diameter in the forming area) of the hollow rivet and can be larger than the inner diameter of the setting head opening, which is formed in the setting head on a locking shoulder adjoining the shank area of ​​the hollow rivet (on the side facing away from the rivet boss head). This limits the setting path of the blind rivet by ensuring that the locking head rests against the locking shoulder of the hollow rivet or abuts it during the setting process and is locked there, for example, by means of a locking mechanism and / or by deformation. During this locking, which preferably occurs during the setting of the blind rivet, e.g.,If the setting process is carried out using a setting tool, the rivet mandrel and the rivet head can continue to move towards the setting head (in the direction of the setting movement or tensile / setting force) until a locking mechanism is activated (e.g., by cold forming and / or mechanical means) and the movement of the rivet head stops. This can occur, in particular, at a position on the rivet head where the mandrel breaks off at a predetermined breaking point.

[0025] This positions and fixes the locking area of ​​the rivet boss on and / or in the setting head of the hollow rivet. In particular, the locking area of ​​the (set) rivet boss can be positioned completely or at least partially in the setting head of the hollow rivet. Preferably, according to a preferred embodiment, the setting head opening can be sealed by the locking area when the hollow rivet is set, i.e., when the end of the setting path is reached. This achieves an overall sealing installation of the blind rivet in the material being joined. For example, a hollow rivet according to the invention can also be used independently of a joining process with multiple materials (material being joined) simply to...

[0026] February 18, 2026 G 200 P 128 WO a reliable sealing closure of openings in the joining material is used, i.e. also in the case of a fastening material.

[0027] It is therefore a preferred feature according to the invention that the proposed blind rivet is always set with the same setting path on a joining or fastening material, regardless of whether a predetermined setting path and / or a predetermined setting force is set by a setting tool, as long as the setting path and / or the setting force are set such that the locking head rests against the locking shoulder after the blind rivet has been set by pulling on the mandrel (and is locked as described above).A minimum clamping length of the blind rivet for a joining material can result from the fact that, when the blind rivet is inserted into an opening of the joining material, and its setting head rests against a first surface of the joining material, the joining material extends axially with the second surface opposite the first surface, for example, into the forming area of ​​the hollow rivet shank or at least almost to the forming area (i.e., it ends before the end of the shank area in the direction of the forming area, so that preferably after setting at least a section of the surface side of the closing head facing the joining material rests against the joining material).

[0028] A maximum clamping length results from the fact that, when the locking head rests against the locking shoulder, the rivet dome head acts on the formed area, creating an (effective) locking head. According to a preferred embodiment, the maximum clamping length can be achieved by ensuring that the diameter of the locking head resting against the second surface corresponds to the diameter of a locking head that is available for any clamping length between the maximum and minimum clamping lengths (also referred to as the entire clamping range). A corresponding diameter is considered to be one where the diameter of the locking head is essentially constant for any clamping length across the entire clamping range.

[0029] February 18, 2026 G 200 P 128 WO not varying by more than + / - 15% or 20%, preferably not by more than + / - 10%. This results in comparable setting properties for the blind rivet across the entire clamping range and is achieved in particular by the fact that the setting path is defined and limited by the locking head, regardless of the maximum tensile force applied, and leads to comparable force introduction and force transmission properties at the joining material.

[0030] According to a further aspect of the invention, the axial length of the locking area of ​​the rivet head can correspond to the axial length of the setting head opening. When the blind rivet is set, the setting head opening is closed by the locking area of ​​the rivet head and completely or almost completely filled. This allows for a comparatively smooth surface on the setting side of the workpiece or fastener during riveting and, for example, improves aerodynamics. According to this embodiment, significantly less filler is required to fill any remaining unevenness on the surface of the setting side in the area of ​​the setting head opening than in the prior art. A smaller filler volume saves effort and prevents the filler from shrinking and causing visual defects. This is particularly true for a countersunk setting head.

[0031] In the case of a ring shoulder that projects axially from the side of the setting head facing away from the workpiece and is pressed into the setting head during the setting process (the structure and function of the ring shoulder will be described in more detail later), and / or a (previously described) relative displacement of the rivet boss when the rivet boss is locked, and / or an axial extension of a portion of the locking head that rests against the locking shoulder in the setting head but is not drawn into the setting head, these axial sections of the setting head and / or the locking head are used to ensure that the axial length of the setting head opening corresponds to the

[0032] February 18, 2026 G 200 P 128 WO Locking area not taken into account. According to the invention, the axial length of the locking area of ​​the rivet boss and the axial length of the setting head opening correspond to each other if the section of the locking area arranged in the setting head opening after the rivet has been set is the same length in the axial direction as the setting head opening. This results in a smooth surface on the workpiece on the surface of the setting head facing away from the locking head after setting, particularly if the setting head is designed as a countersunk head.

[0033] Furthermore, the rivet mandrel almost completely fills the setting head (which can be designed as a countersunk or flat head) after the blind rivet is set (especially with the locking area of ​​the rivet boss) and contributes to the mechanical stability of the setting head, preventing it from being compressed or crushed. This increases the load-bearing capacity of the riveted joint. According to the invention, the axial length of the locking area of ​​the rivet boss accommodated in the setting head and the axial length of the setting head opening can be precisely coordinated by ensuring that the locking head of the rivet boss abuts the locking shoulder of the hollow rivet and forms the locking mechanism. This defines the setting path.

[0034] It can be particularly advantageous if, according to one embodiment of the invention, the locking area of ​​the rivet boss has the locking head at the end of the locking area facing the rivet boss head shaft. In this way, the locking area is reliably positioned in the setting head opening when the setting path is limited by the locking head bearing against the locking shoulder and the formation of the locking mechanism.

[0035] In addition to or independently of this, according to a further embodiment, the locking area of ​​the rivet boss at the end facing the mandrel can have a predetermined breaking point, which is, for example, a groove in a

[0036] February 18, 2026 G 200 P 128 WO The locking shank can be formed in the locking area of ​​the rivet head. When the pull mandrel reaches the end of its setting path and the tensile force Z continues to be applied to the rivet mandrel, the pull mandrel breaks off from the locking area held in the setting head at the predetermined breaking point. This terminates the setting process of the blind rivet. The groove of the predetermined breaking point can be designed as a triangular groove, preferably as a triangle with legs of different lengths, whereby the shorter leg can be located on the side of the locking area. Correspondingly, the longer leg is located on the side of the pull head. This achieves the smoothest possible surface. According to one embodiment of the invention, the notch base of the groove can be designed as a radius or curved contour.In another embodiment, the contour of the groove can consist of differently designed straight or curved shapes.

[0037] A particularly preferred embodiment of the invention provides that a locking groove is formed in the locking area (preferably directly in the direction of the pull boss) adjacent to the locking head. This creates a positive locking mechanism internal to the setting head. This internal locking mechanism is protected against external influences and secures the rivet mandrel in the hollow rivet against movement relative to the hollow rivet that could lead to loosening of the rivet joint. Therefore, a rivet joint secured in this way is particularly stable and durable, especially in applications where strong vibrations act on the set blind rivets, such as in aircraft.Unlike an externally actuated mechanical locking mechanism (such as those found in standards ASNA0079, ASNA0080, and the referenced standard NAS1722), this internal locking mechanism according to the invention does not require particularly sensitive nozzle contours on the setting tool to ensure high process stability and repeatability when processing (setting) these blind rivets. This minimizes tool wear on the setting tool.

[0038] February 18, 2026 G 200 P 128 WOes There is no risk of overlooking wear on the mouthpiece of the setting device that would have a negative impact on the stability of the locking mechanism.

[0039] When the blind rivet is set, material flows from the rivet head into the locking groove, particularly when the locking head, subjected to tensile force Z at the end of its setting stroke, abuts the locking shoulder and the rivet is locked. This internal positive-locking connection secures the rivet mandrel against axial displacement within the rivet when the blind rivet is set. This is especially important when the blind rivet joint is subjected to strong vibrations during use, for example, in riveted joints in aircraft construction. Such an internal connection is particularly advantageous because it is especially protected against external mechanical influences and, due to the flow of the material, creates not only a positive-locking but also a friction-locking connection between an inner surface of the rivet head opening and a (solely by the locking groove and, if applicable, a)The structured outer surface of the rivet boss (with additional structural elements) is achieved in the locking area. The rivet mandrel is locked internally in the area of ​​the setting head, providing both a force-fit and, above all, a form-fit connection.

[0040] The rivet head with its flange, whose shoulder remains in contact with the closed head on the open end face of the hollow rivet's forming area even when the blind rivet is set, allows axial forces to be absorbed and transmitted not only by the hollow rivet itself but also by the mandrel. These forces contribute to the rivet's holding force. This achieves two effects: Firstly, a portion of the tensile force (setting force) is retained as a preload. Without this locking mechanism, a portion of the tensile stress would be released after the mandrel breaks during rivet setting, would no longer be available as an axial force component in the rivet joint, and could even lead to the so-called bounce-back effect.

[0041] February 18, 2026 G 200 P 128 WO The movement of the rivet mandrel elements, which, after the mandrel breaks at the predetermined breaking point, are located within the hollow rivet shank, the workpiece, and the rivet joint, describes a direction opposite to the setting movement and can thus reduce the axial clamping force of the rivet joint. Furthermore, axial forces acting on the rivet joint during operation of the set hollow rivet are transmitted. These axial forces are partially transmitted through the hollow rivet (wall) and partially through the rivet mandrel (head), and not exclusively through the hollow rivet (as in corresponding rivet joints of the prior art without a corresponding locking mechanism). This increases the stability of rivet joints (especially those subjected to high mechanical stress).

[0042] Material flow in connection with the setting of the rivet joint primarily refers to cold flow of the material due to the application of force. According to the invention, cold flow comprises deformation below the recrystallization temperature of the blind rivet material and results in particularly high strength. This can be, in particular, cold forming at ambient temperature or semi-warm forming. In semi-warm forming, the workpiece is heated to a temperature that is still below the recrystallization temperature. This combines the advantages of hot forming (easier formability and higher formability) with the advantages of cold forming (work hardening, higher accuracy).

[0043] There are various measures that, individually or in combination with other or all measures, promote the flow of the material and / or the positive and / or non-positive connection of the rivet mandrel and the hollow rivet. These are each described individually below, but according to the invention, they can each be applied alone or in any combination with one another.

[0044] February 18, 2026 G 200 P 128 WO An optional measure according to the invention can provide that the locking shoulder of the hollow rivet is formed as a chamfered or slotted shoulder, wherein the material of the hollow rivet forms a first acute angle between the setting head opening and the chamfered or slotted shoulder. This facilitates the flow of material in the region of the acute angle from the hollow rivet into the locking groove of the rivet head when the blind rivet is set.

[0045] A comparable optional measure according to the invention can provide that the locking head is formed as a chamfered or slotted shoulder at the transition into the locking groove, wherein the material of the locking head forms a second acute angle between an outer circumferential surface of the locking head and the chamfered or slotted locking groove. This also promotes the flow of material in the region of the acute angle from the hollow rivet into the locking groove of the rivet head when the blind rivet is set.

[0046] The two measures described above combine to create a special effect. Due to the design of the chamfered or slotted shoulders in different axial directions of the hollow rivet and rivet mandrel, the shoulders form opposing points which interlock when the rivet head is moved within the hollow rivet during the setting of the blind rivet, thus promoting the flow of material, especially from the hollow rivet, into the locking groove particularly effectively.

[0047] A further optional measure according to the invention can provide that a separate deformable locking element is arranged in the shank area of ​​the hollow rivet between the locking shoulder of the hollow rivet and the locking head of the rivet boss, which engages in the locking groove of the rivet boss when the blind rivet is set and is pressed in place. According to preferred

[0048] February 18, 2026 G 200 P 128 WO The separate locking element can be designed as a sealing ring made of a metal that is softer than the hollow rivet and the mandrel, as a microencapsulated adhesive, and / or as an adhesive ring cushion. The microencapsulated adhesive or the adhesive of the adhesive ring cushion is released during the force-actuated setting of the blind rivet, resulting in bonding between the hollow rivet and the mandrel in the locking area. This bonding creates a further force-fit and material-fit connection and simultaneously provides a seal.

[0049] A further optional measure according to the invention can provide that a locking shank, extending from the locking head or locking groove towards the draw mandrel in the locking area, has a locking shank diameter that is larger than the inner diameter of the setting head opening and smaller than the locking head diameter. The locking shank diameter is dimensioned such that, when an axial tensile force is applied to the draw mandrel, the locking shank can be drawn into the setting head opening of the hollow rivet due to radial pressure, resulting in cold deformation of the setting head of the hollow rivet and / or locking shank. The increased radial pressure can promote the axial flow of material from the hollow rivet in the setting head area. This quickly leads to the effective filling of the material-free locking groove in the rivet mandrel.The flow of material from the hollow rivet in the setting head area can optionally be further facilitated by forming a chamfer at the transition from the mandrel (with a pull dome diameter) to the locking shank (with a locking shank diameter). This chamfer facilitates the insertion of the locking shank into the setting head opening by continuously increasing the radial pressure on the material in the setting head during axial movement of the rivet dome in the direction of the pull force Z. The chamfer also prevents or minimizes material abrasion in the setting head opening, which is then used to form the locking mechanism.

[0050] February 18, 2026 G 200 P 128 WO would be missing. Furthermore, the surface and any surface coatings in the setting head opening are not damaged. This prevents the formation of abrasion and contamination. The pull dome diameter preferably corresponds exactly to the inner diameter of the setting head opening.

[0051] Another effect, independent of the one described above, can be that the setting head and the setting head opening are hardened by cold forming. This increases the stability of the rivet boss's locking mechanism in the setting head (both through frictional engagement between the locking area of ​​the rivet boss and the setting head opening, and through positive engagement by means of the additional cold-worked material that fills the locking groove). The additional material of the aforementioned ring shoulder, also resulting from cold forming, contributes to this effect as well.

[0052] Preferably, the largest outer diameter of the pull-dome chamfer can be larger than the locking shank diameter and smaller than the locking head diameter. This allows material from the setting head to deflect in the axially opposite direction to the direction of movement of the rivet boss during setting the blind rivet, because a space is created behind the pull-dome chamfer in the locking area, into which some of the material flows and enters the locking groove.

[0053] The locking groove described above provides a particularly secure internal (i.e., inside) locking mechanism in the setting head, which is not accessible from the outside after setting and therefore cannot be influenced.

[0054] At the end of the blind rivet's setting path, the pull-out chamfer is preferably located outside the setting head. This can be easily achieved by positioning the pull-out chamfer between the predetermined breaking point at the end of the locking area and the pull mandrel.

[0055] February 18, 2026 G 200 P 128 WO According to a preferred embodiment of the invention, the locking groove of the rivet head, when the blind rivet is set, can be arranged in a radial plane in the setting head of the hollow rivet that coincides with the surface of the workpiece or fastener on the setting side or that is located within the workpiece or fastener. In the area of ​​the locking groove, high radial forces are generated under axial load due to the positive-locking interlocking of the rivet mandrel and the hollow rivet, which increase the frictional connection between the hollow rivet and the workpiece or fastener. Therefore, according to the invention, it is preferred if a radial force in the area of ​​the locking groove is transferred directly to or supported by the opening in the workpiece or fastener.

[0056] A radial plane is defined as a plane oriented perpendicular to the axial direction of the blind rivet. The axial direction is defined by the longitudinal axis of the rivet head and the longitudinal axes of the hollow rivet shank and the setting head opening, all of which have the same orientation. The setting side is defined as the side of the workpiece or fastener on which the setting head of the blind rivet is located. In the case of a flat head, the setting head rests on the surface of the workpiece or fastener; in the case of a countersunk head, the setting head is recessed into the surface of the workpiece or fastener.

[0057] According to a specific embodiment of the invention, the locking groove of the rivet head can be arranged in a radial plane that runs within the workpiece or fastener when the blind rivet is set. This allows radial forces generated in this area to optimally contribute to a positive-locking connection between the blind rivet and the workpiece or fastener. This is directly the case with a countersunk rivet head. Even with a flat-head rivet head, the locking shoulder can be recessed to such an extent that the locking head and the locking groove are aligned when the rivet is set.

[0058] February 18, 2026 G 200 P 128 WOBlind rivets are arranged within the workpiece or fastener. This design achieves a particularly high strength of the riveted joint.

[0059] In a further embodiment, the setting head can have an annular shoulder projecting axially outwards towards the free end of the pull boss around the setting head opening. The annular shoulder, hereinafter also referred to more generally as a thickening, extends radially from a central axis of the setting head opening with a radius that is preferably less than or equal to the radius of the outer circumference of the hollow rivet shank. The term "radius" is not necessarily to be understood as meaning that the thickening and / or the hollow rivet have a circular outer circumference. The term "radius" is also intended to encompass other outer contours (with varying radial extents depending on the radial direction).

[0060] A key advantage of the thickened section is that, due to the counterforce-generating contact surface of the setting tool (e.g., the tool's nozzle), it flows into the rivet head during setting. This facilitates the flow of material from the hollow rivet or the rivet head into the locking groove and / or other structures within the rivet boss's locking area, and cold forming leads to work hardening of the rivet head. Furthermore, in this area, the hollow rivet material is pressed radially against the rivet boss shank, which enhances the rivet boss's braking action (i.e., it counteracts the setting force and helps prevent the rivet boss from being pulled through the hollow rivet). This contributes to a tight seal and stabilizes the rivet boss's guidance (radial support).This also serves to optimally utilize the load-bearing capacity in the area of ​​the rivet head by maximizing cavity filling and creates an additional force-fit between the rivet mandrel and the hollow rivet for the transmission of tensile forces, as well as a positive fit for the transmission of shear forces. This prevents the rivet head from slipping in extreme cases (given...).

[0061] February 18, 2026 G 200 P 128 WO (Installation situation, e.g., oval) could be crushed, which would negatively affect the load-bearing capacity. The work hardening of the hollow rivet material also helps to prevent over- or under-tightening of the rivet boss or failure of the internal locking bead, which forms in the locking groove during the setting process.

[0062] According to a further embodiment, a mechanical locking mechanism can be provided at the end of the locking area facing the mandrel (preferably directly adjacent to a predetermined breaking point of the rivet boss), which locks the rivet mandrel in the setting head after the blind rivet has been set.

[0063] Such a locking mechanism formed at the open end of the setting head opening can preferably be implemented in addition to, or possibly also as an alternative to, the internal locking mechanism already described above.

[0064] One specific embodiment may provide that tabs are formed on the outer circumferential edge of the locking area in the direction of the pull mandrel. These tabs have a free end resting against the outer circumference of the locking area in the direction of the pull mandrel and are designed to fold radially outwards. Preferably, the tabs project radially beyond the pull mandrel. The folding action can be effected, for example, by a nozzle of a blind rivet setting tool. This nozzle exerts a counterforce on the setting head, opposing the tensile force Z on the pull mandrel. During the setting process, the nozzle engages a gap between the free end of the tabs and the locking area by pulling on the pull mandrel, bending the tabs radially outwards. A recess in the setting head, into which the bent tabs engage, is preferably provided for this purpose.This ensures that the rivet head is fixed against the locking head after installation, further securing the blind rivet connection with a form-fit connection.

[0065] February 18, 2026 G 200 P 128 WO According to another embodiment, the locking area at its end facing the mandrel can have an undercut, and a slot surrounding the undercut can be formed in the setting head. A locking ring is pressed into this slot when the blind rivet is set. The slot surrounding the undercut tapers radially towards the rivet head. When the locking ring is pressed into the slot surrounding the undercut during the setting of the blind rivet, for example, by a nozzle of the setting tool, the ring deforms and secures the rivet mandrel in the setting head. The effect is comparable to the embodiment described above.

[0066] According to a further aspect of the invention, an undercut can be formed on the rivet head shoulder and / or a groove engaging in the rivet head and / or the rivet head shank at the transition from the rivet head to the rivet head shank. This creates a positive-locking connection between the rivet head shoulder and the open end face of the formed area (with a relatively low holding force). This stabilizes the connection between the rivet head formed when the blind rivet is set and the rivet head, and thus the entire rivet joint, by ensuring that the edge of the formed area engages or flows into the undercut and / or groove when the blind rivet is set. The undercut on the rivet head provides additional security against the rivet head slipping into the hollow rivet.The term "slip-in" refers to the prevention of relative movement between the rivet head and the end of the forming area of ​​the hollow rivet opposite the setting head after they have made contact. This end of the forming area of ​​the hollow rivet forms the outer end face of the hollow rivet, which lies in a radial plane and serves as the contact surface between the forming area of ​​the hollow rivet and the lower surface of the rivet head shoulder.

[0067] February 18, 2026 G 200 P 128 WOEs According to the invention, the rivet mandrel can have a cavity extending axially at least through the rivet head (and preferably concentric with the central axis of the rivet head). The ratio of the inner diameter of the cavity to the outer diameter of the shank area of ​​the rivet head can be, for example, 0.2 and 0.8, more preferably between 0.4 and 0.7, and particularly preferably between 0.5 and 0.6. The cavity is preferably open on the side of the rivet head opposite the mandrel and is, for example, designed as an axial bore.

[0068] If the rivet mandrel is designed as a solid bolt or if a cavity extends only to the rivet head, the shank section of the hollow rivet that is inserted into an opening in the workpiece (fastening hole) is completely filled with material from the rivet head. The rivet mandrel, designed as a solid bolt in this area, is not compressible or only slightly compressible. This means that the outer diameter of the hollow rivet must be able to expand sufficiently within the opening in the workpiece to fill the opening securely and, for example, to create a force-fit connection by generating the desired bearing pressure in the opening. For this to occur, the opening in the workpiece must be sufficiently small.On the other hand, the opening in the joining or fastening material must be large enough that the rivet head shaft, with the applied setting force when being pulled into the shaft area, does not generate too much hole bearing pressure and get stuck or cause damage to the joining or fastening material.

[0069] The suitable ranges for the opening diameter in the material to be joined or fastened are relatively small and can be determined by a specialist, for example, through measurements or tests, depending on the material. This material dependency applies both to the material being joined or fastened.

[0070] February 18, 2026 G 200 P 128 WO also with regard to the material and properties of the hollow rivet and rivet mandrel, e.g., through coatings, surfaces with increased hardness or sliding coatings, as well as additional sealants or adhesives used in assembly. The material and properties of the hollow rivet and rivet mandrel can be the same or different.

[0071] Solid rivet heads in the shank section result in high stability and strength when shear forces occur perpendicular to the joining direction in a joint, i.e., at least two different bodies of the same or different materials. In this case, rivet heads designed as solid rivet heads in the rivet head shank are advantageous. Cavities in the rivet head area do not impair shear stability and result in a certain weight saving. This can be advantageous depending on the application, e.g., in aircraft construction.

[0072] In another embodiment, the cavity can extend partially or completely through the rivet head shank. A cavity extending completely through the rivet head shank can extend axially from the rivet head to the locking area, for example, axially to or into the insertion chamfer. This achieves high plasticity or compressibility of the rivet head shank and maximum weight savings. However, with at least two joining materials, forming the cavity in the rivet head shank can reduce the absorption of shear forces if the joining materials shift or can shift perpendicularly or obliquely to the axial direction.If such shear forces arise and are to be absorbed by the rivet joint, it is advantageous in the area where the shear forces occur if the rivet head shank is designed as a solid bolt (which allows the highest absorption of shear forces) or if a cavity extends from the shooting head in the axial direction to a maximum extent into the first joining material.

[0073] February 18, 2026 G 200 P 128 WO Extended, i.e., at most to the surface of the first joining material facing away from the shooting head, and preferably only to about the middle of the first joining material.

[0074] According to a further embodiment of the invention, a surface structure can be incorporated or present in the outer circumferential region of the rivet head shank, for example, embossed or introduced. This surface structure is pressed into the inner circumference of the hollow rivet when the rivet head shank of the rivet head is inserted into the shank region of the hollow rivet. This results in a higher riveting force due to a stronger connection between the surfaces of the rivet mandrel and the hollow rivet by increasing the frictional engagement and generating at least a slight positive locking effect. In one embodiment, the surface structure can be achieved by groove-shaped serrations, particularly in the circumferential direction on the outer circumference of the rivet head shank. According to a particularly preferred embodiment, the serrations can have barbs that act against the tensile force during the setting of the blind rivet when the rivet head is moved and are accordingly asymmetrically designed.

[0075] Furthermore, adhesive can optionally be provided at least partially on the rivet head shank of the rivet boss, for example, in a gap between the rivet head shoulder and the open end face of the hollow rivet shank before the blind rivet is set. According to one embodiment, the adhesive can also be provided in, for example, embossed surface structures of the rivet head shank to bond the rivet head shank of the rivet boss and the shank area of ​​the hollow rivet by means of an additional material bond when the blind rivet is set. For this purpose, a suitable adhesive gap can be formed, for example, in the radial direction, in the axial direction, or at an angle thereto (e.g., as a threaded gap, diamond-shaped gap, or the like). Suitable adhesive, such as that used in aerospace engineering, can be introduced into the surface structures before the blind rivet is set. It is also possible to apply the adhesive to the hollow rivet and / or the

[0076] February 18, 2026 G 200 P 128 WO Applying a microencapsulated adhesive coating to the rivet mandrel's surface and / or surface structures. This can be done during the manufacturing process of the blind rivet, i.e., the production of the hollow rivet and rivet shank. Due to the positive-locking connection between the hollow rivet and rivet shank, the microencapsulated adhesive ruptures when the blind rivet is set (both on the surface and within surface structures), resulting in an additional bond between the rivet joint.

[0077] Alternatively or additionally to the adhesive, a lubricant can be applied (e.g., to the surface structures, particularly the surface structures of the rivet head shank) to simplify the setting process and prevent jamming of the hollow rivet and rivet mandrel during setting, i.e., during the setting process when the rivet mandrel is moving within the hollow rivet, which could potentially impair the holding force (preload force) of the set rivet joint. Since the adhesive also has a friction-minimizing effect, an additional lubricant may be unnecessary when using adhesive.

[0078] If, according to the invention, the use of lubricant and / or adhesive can be dispensed with on the hollow rivet (and lubricant and / or adhesive is applied exclusively to the rivet mandrel), this offers advantages when painting the hollow rivets before or after setting and other finishing work, such as filling.

[0079] According to a further aspect of the invention, in one embodiment, the hollow rivet shank can have different areas of varying stiffness, particularly in the forming area. This allows the formation of the rivet head to be specifically influenced according to the invention. Preferred methods for creating areas of varying stiffness according to the invention include, for example, locally reduced wall thicknesses or hardened areas through mechanical processes.

[0080] February 18, 2026 G 200 P 128 WO Stiffening or localized hardening (e.g., by aging of alloying elements and / or alloy compounds, also under prior localized heat) may be used. Mechanical stiffening or reduced wall thicknesses can be produced by localized embossing, pressing, and / or knurling (rolling). According to a preferred embodiment, one or more (particularly preferably two) ramps can be formed in the forming area, which (in the case of multiple ramps) are preferably formed in opposite directions axially. A ramp can be formed by embossing the outer circumference of the forming area of ​​the hollow rivet to varying depths in the axial direction. In the case of ramps in opposite directions, the areas of deepest indentation are preferably located opposite each other at the axially furthest apart ends.The areas of deepest indentation represent the preferred bending points during the formation of the rivet head from the forming area. The ramps can be subdivided into several ramp sections in the circumferential direction of the hollow rivet by axial longitudinal struts. In the shank area of ​​the hollow rivet, axial longitudinal grooves can be indented on the outer circumference for stabilization and / or improved contact.

[0081] Furthermore, according to one embodiment of the invention, the hollow rivet shank (particularly only or at least in the shank region) may have axially extending indentations and / or a variable cross-section on its outer and / or inner circumference, for example, a polygonal shape deviating from a round cross-sectional area. This allows blind rivets to be set with larger tolerances in the openings (bores) of the joining elements or fastening elements because, due to the variation in the inner and / or outer circumference, material from the blind rivet may shift circumferentially during setting if the opening diameter were so small that the rivet mandrel would otherwise become jammed in the hollow rivet shank before the blind rivet is fully set. This also allows for the implementation of an anti-rotation device.

[0082] February 18, 2026 G 200 P 128 WOF Furthermore, according to one embodiment of the invention, the rivet head shank may have axially extending indentations on its outer circumference and / or a variable cross-section (e.g., a shape deviating from a round cross-sectional area, such as a polygonal shape). This achieves a similar effect to the previously described structure of the outer circumference and / or inner circumference of the hollow rivet shank. Both features can also be combined according to the invention.

[0083] A particular advantage of the blind rivet described according to the invention is that the blind rivet expands radially within the workpiece or fastener, thereby achieving particularly good hole bearing and contact qualities by means of a force-fit connection and simultaneously a rivet head that bears a large area on the workpiece or fastener, creating a reliable form-fit and force-fit connection. In contrast to screw or bolt connections, which require access from both sides at the assembly point, the invention achieves a highly stable blind rivet connection with excellent hole bearing properties and high rivet joint stability, due to the combination of an effective force-fit and an effective form-fit connection, which only requires access from one side at the assembly point.Preferably, when setting the blind rivet in the setting tool, no additional processing parameters, such as setting force and / or setting distance or torque in the case of a screw connection, need to be set. Therefore, simple and reliable assembly is achieved. Processing parameters such as setting force and setting distance do not need to be set because the setting distance is inherently predetermined or defined by the locking of the locking area in the setting head opening, and the (maximum) setting force is determined by the formation of the predetermined breaking point in the locking area. This effectively counteracts faulty assembly according to the invention.

[0084] February 18, 2026 G 200 P 128 WO Further advantages, features, and applications of the invention will also become apparent from the following description of exemplary embodiments and the drawing. All described and / or illustrated features, together or in any technically sensible combination, belong to the subject matter of the invention, even independently of their compilation in described or illustrated exemplary embodiments or in the claims.

[0085] They show:

[0086] Fig. 1 shows a cross-sectional embodiment of an unset blind rivet according to the invention;

[0087] Fig. 2 shows a section of the rivet mandrel according to Fig. 1 in a side view;

[0088] Fig. 3 schematically shows a force flow in a set blind rivet according to Fig.

[0089] 1;

[0090] Fig. 4 shows a locking area of ​​the rivet boss and a locking shoulder of the hollow rivet according to a further embodiment;

[0091] Fig. 5 shows a locking area of ​​the rivet boss and a locking shoulder of the hollow rivet according to a further embodiment;

[0092] Fig. 6a,b,c shows in cross-section an uninstalled blind rivet according to Fig. 1 in a joining material (a), a installed blind rivet according to Fig. 1 with maximum clamping range (b) and a installed blind rivet according to Fig. 1 with a minimum clamping range (c);

[0093] February 18, 2026 G 200 P 128 WOFig. 7a,b,c in cross-section an unset blind rivet according to Fig. 1 with a rivet mandrel with a deep cavity in the shank area (a), with a rivet mandrel with a shallow cavity in the shank area (b) and with a rivet mandrel with no cavity in the shank area (c) according to further embodiments;

[0094] Fig. 8a, b shows an uninstalled rivet mandrel with surface structures according to a further embodiment in a side view in a cut-section hollow rivet (a) and the installed rivet mandrel according to Fig. 8a in cross-section;

[0095] Fig. 9a,b,c shows a rivet dome head shaft in cross-section from the direction of the pull dome and in side view in various embodiments, each with a variable polygonal cross-section (a), a round cross-section with axial longitudinal grooves (b) and a variable polygonal cross-section with axial longitudinal grooves;

[0096] Fig. 10a,b,c,d shows a hollow rivet in cross-section through the shank area from the direction of the forming area and a half-sectioned side view in various embodiments, each with notches on the inner circumference of the shank area (a), with notches on the outer circumference of the shank area (b), with notches on the inner circumference and inner circumference of the shank area (c) and with a variable polygonal cross-section in the inner circumference (d); and

[0097] Fig. 11a,b,c,d,e shows an unset blind rivet with hollow rivet in side view with hollow rivets in various embodiments, in (a) according to Fig.

[0098] 1, in (b) with a first ramp at the end of the forming area facing the rivet head, in (c) with a second ramp at the end of the forming area facing the shaft area, in (d) with a first and a second ramp in the forming area and in (e) with

[0099] February 18, 2026 G 200 P 128 WO a first and a second ramp in the forming area and a knurled area in the shaft area.

[0100] Figure 1 shows a blind rivet 1 according to a preferred embodiment of the invention. The blind rivet 1 has a hollow rivet 2 and a mandrel 5 guided in the hollow rivet 2, the hollow rivet 2 being shown in a longitudinal section and the mandrel 5 in a side view. The hollow rivet 2 has a setting head 3 with an axial setting head opening 30 and a hollow rivet shank 4 extending axially from the setting head 3. The mandrel 5 has a rivet dome head 6, a rivet dome head shank 60 extending axially from the rivet dome head 6, an axially extending drawbar 7 (which is also referred to synonymously as rivet dome shank in this text), and a locking area 8 formed between the rivet dome head shank 60 and the drawbar 7. The rivet head 6 has an insertion chamfer 9 to facilitate the insertion of the blind rivet 1 into an opening 103 of the joining material or fastening material 100.

[0101] The mandrel 7 is guided axially movably in the setting head opening 30, and the setting head 3 and the rivet dome head 60 are arranged axially on different sides of the hollow rivet shank 4, wherein a head shank diameter D1 of the rivet dome head shank 60 is larger than an inner diameter in the shank region 31 of the hollow rivet 2 adjoining the setting head 3 and is dimensioned such that, when an axial tensile force Z is applied to the mandrel 7, the rivet dome head shank 60 can be drawn into the shank region 31 of the hollow rivet 2 by means of cold deformation of the shank region 31 and / or rivet dome head shank 60 due to radial pressure, until the locking area 8 of the rivet dome 5 is positioned and fixed on or in the setting head 3 of the hollow rivet 2.

[0102] The hollow rivet 2 has a forming area 32 on the side facing away from the setting head 3, adjacent to the shank area 31, for forming a

[0103] February 18, 2026 G 200 P 128 WOC fitting head 33, wherein an inner diameter of the forming area 32 is larger than an inner diameter of the shank area 31. The inner diameter of the forming area 32 can preferably correspond to the head shank diameter D1, so that the rivet dome head shank 60 is slidable in the forming area 32 without friction or with low friction, but guided. The rivet head 6 has a rivet head flange 61 at the end of the rivet head shaft 60 facing away from the locking area 8, which projects radially outwards from the rivet head shaft 60 with a rivet head shoulder 62 and, in the event of axial movement of the rivet head 5 in the direction of the tensile force Z, engages an open end face 63 of the forming area 32 of the hollow rivet shaft 4 in order to form the locking head 33 by deforming the forming area 32 when the tensile force Z is applied further to the mandrel 7 (rivet head shaft).The formation of the locking head 33 is typically carried out by folding the forming area outwards (i.e. in a radial direction perpendicular to the axial direction in the direction of the central axis of the rivet dome 5).

[0104] The transition from a larger inner diameter of the hollow rivet shank 4 in the forming area 32 to a smaller inner diameter of the hollow rivet shank 4 in the shaft area 31 occurs in a transition area 34 by a stepped transition, as shown here, or by a chamfered or curved transition. The transition from the larger inner diameter in the shaft area 31 to the smaller inner diameter in the setting head opening 30 occurs via an edge-like locking shoulder 35, which interacts with the locking area 8 when the blind rivet 1 is set. Accordingly, a chamfer 64 can preferably be provided at the end of the rivet head shank 60 facing the locking area 8, where the larger head shank diameter D1 transitions to a smaller locking head diameter D2. The locking head diameter D2 can correspond to the inner diameter in the shaft area 31 of the hollow rivet shank 4, so that

[0105] February 18, 2026 G 200 P 128 WO that the locking head 80 of the locking area 8 is movable in the shaft area 31 without friction or with low friction, but guided.

[0106] In a preferred embodiment, the locking head diameter D2 of the locking head 80 is correspondingly smaller than (or substantially equal to) the inner diameter in the shank region 31 of the hollow rivet 2 and larger than the inner diameter of the setting head opening 30, which is formed in the setting head 30 adjacent to the locking shoulder 35 (on the side facing away from the rivet head). The setting path of the blind rivet 1 is limited by the fact that, when the blind rivet is set by pulling in the direction of the tensile force Z, e.g., by a setting tool, the locking head 80 abuts the locking shoulder 35 and activates a locking mechanism there (in particular by deformation) until a locking action is effected and movement of the rivet head 5 in the direction of the tensile force 7 is stopped.

[0107] Figure 1 shows a preferred relative position of the hollow rivet 2 and the rivet mandrel 5 before the blind rivet 1 is set, approximately in an initial state (also referred to as the delivery state) of the blind rivet 1, in which the locking head 80 of the rivet boss 5 is arranged in the transition area 34 of the hollow rivet 2, preferably such that the locking head 80 is positioned in the shank area 31 and the rivet boss head shank 60 (optionally completely or partially including any chamfer 64) is positioned in the forming area 32. In this initial state, no radial forces act on the blind rivet 1 that radially widen the hollow rivet shank 4, so that it can simply be inserted into an opening in the workpiece (hereinafter also referred to as the fastening opening).In this initial state, the mandrel 5 can be held in position in the hollow rivet 2, so that the mandrel 5 and the hollow rivet 2 can move relative to each other during the transport of the blind rivet 1 and when the blind rivet 1 is guided into the fastening opening under the forces that usually act upon it, which are significantly smaller than the tensile force.

[0108] February 18, 2026 G 200 P 128 WOZ, do not shift. In the embodiment shown here, this is achieved by a mandrel knurling 70, the knurling diameter D5 of which (based on its largest outer circumferential area) is larger than the diameter D4 of the mandrel 7. The diameter D4 corresponds exactly to the inner diameter of the setting head opening 30, so that the mandrel 7 can move axially with low or no friction in the setting head opening 30, but is guided. The knurling diameter D5 of the mandrel is minimally larger than the inner diameter of the setting head opening 30, so that the mandrel 7 is positively locked to the mandrel knurling in the setting head opening, the locking being released by applying the tensile force Z with essentially no deformation or minimal deformation.

[0109] Fig. 2 shows the locking area 8 of the rivet boss 5 in detail. The axial length of the locking area 8 of the rivet boss 5 essentially corresponds to the axial length of the setting head opening 30 in the setting head 3, in particular the axial length of the locking area 8 between the locking head 80 and a predetermined breaking point 83 (whereby the predetermined breaking point 83 and the locking head 80 are preferably not included in the axial length of the locking area 8). This ensures that, when the blind rivet 1 is set, the setting head opening 30 is almost completely closed by the locking area 8 if the mandrel 7 of the rivet boss 5 has broken off at the predetermined breaking point 83 after setting. Preferably, the axial length of the locking area 8 is dimensioned such that, after setting the blind rivet 1 and breaking off the pull dome 7 from the rivet mandrel 5, no section of the rivet dome 5 protrudes beyond the exposed setting head surface, as shown in Fig. 3.

[0110] The construction of the locking area 8 is explained below in the axial direction starting from the locking head 80 towards the pull pin 7. A locking groove 81 adjoins the locking head 80 (directly in the particularly preferred embodiment shown here), which is separated from the outer circumference of the locking head 80 and the

[0111] February 18, 2026 G 200 P 128 WO The outer circumference of the locking shaft 82, which extends axially further from the locking groove 81, is recessed. In other words, the diameter of the locking groove 81 at its base is smaller than the locking head diameter D2 and the locking shaft diameter D3. The locking shaft diameter D3 itself is smaller than the locking head diameter D2 and can correspond approximately to the inner diameter of the setting head 30, and is particularly preferably somewhat larger than the inner diameter of the setting head 30, so that the locking shaft 82 itself forms a force-fit connection in the setting head 3.

[0112] At the end of the locking shaft 82, or rather the locking area 8, facing the mandrel 7, a further radially inwardly directed groove is formed. This groove serves as a predetermined breaking point 83 when the locking head 80 rests against the locking shoulder 35, the locking mechanism has engaged, and the rivet mandrel can no longer be moved axially in the direction of the tensile force Z, even with an increase in the tensile force Z. Then the mandrel 7, on which the tensile force Z is exerted, breaks off at the predetermined breaking point 83, supported against a counterforce G acting on the setting head 3, which absorbs the tensile force.

[0113] On the side of the predetermined breaking point 83 opposite the locking shaft 82 and facing the pull mandrel 7, a pull dome chamfer 84 is provided, which reduces the outer diameter in the locking area 8 of the rivet boss to the pull dome diameter D4. At the end of the pull dome chamfer 84 facing the predetermined breaking point 83, where the outer diameter of the pull dome chamfer 84 is preferably largest, the outer diameter of the pull dome chamfer 84 is, according to the invention, preferably approximately between the locking shaft diameter D3 and the locking head diameter D2, particularly preferably approximately in the region of the locking shaft diameter D3 or slightly larger. This results in a high radial pressure on the material of the setting head 3 at the inner circumference of the setting head opening 30 when the pull dome chamfer 84 enters the rivet boss.

[0114] February 18, 2026 G 200 P 128 WO in the area of ​​the locking shoulder 35, so that a flow of material of the setting head 3 is favored, in particular by cold forming into the locking groove 81, as well as by the pressure of the locking head 80 on the locking shoulder 35.

[0115] The material of the setting head 3, which flows into the locking groove 81, is particularly strong due to cold forming and thus creates a very stable internal locking of the rivet boss 5 in the hollow rivet 2 after the blind rivet 1 has been set. This locking also acts as a positive locking mechanism, thereby securing the blind rivet connection. This is particularly advantageous for safety applications, especially for mechanically stressed connections, such as in the aerospace sector (aircraft construction).

[0116] This effect is explained in more detail with reference to Fig. 3, which shows a blind rivet 1 set in a fastening opening 103 of a joining material 100 made of a first joining material 101 and a second joining material 102.

[0117] The hollow rivet 2 is positioned in the fastening opening 103 such that the setting head 3 rests against the second joining material 102 and holds it in a form-fit manner. The closing head 33 is formed at the end of the hollow rivet 2 opposite the setting head 3. This closing head is formed by deformation from the forming area 32 of the hollow rivet shank 4. The rivet head 6 engages the free end 63 of the hollow rivet shank 4 and transmits the tensile force Z to the forming area 32. The closing head 33 rests against the first joining material 101 and holds it in a form-fit manner. The first joining material 101 and the second joining material 102 are clamped by the setting head 3 and the closing head 33. The clamping action absorbs the separating forces T of the first and second joining materials 101 and 102, which are represented by thick arrows in Fig. 3. For this to happen, corresponding clamping forces K must be exerted by the blind rivet 1 on the surfaces of the first and second joining material 101, 102.The entire force flow of the clamping forces K can.

[0118] February 18, 2026 G 200 P 128 WO This produces the hollow rivet 2 and additionally the rivet mandrel 5 and the rivet head 6, which transmits part of the clamping force to the closing head 33 of the hollow rivet 4. The force flow is schematically represented by the thin arrows in the hollow rivet 2 and the rivet mandrel 5.

[0119] As with any blind rivet joint, axial forces act along the hollow rivet shank 4. These forces, acting through the locking head 33 and the setting head 3, exert clamping forces K on the surfaces of the joining materials 101, 102, opposing the separation forces T. Due to the internal locking of the rivet boss 5 in the locking area 8, axial forces can also be partially transmitted between the locking groove 81, filled with material from the setting head 3, and the open end face 63 of the hollow rivet shank 4 (via the setting head 6), as shown in Fig. 3 in a preferred embodiment. This second, parallel force path then carries a portion of the clamping force K and thus contributes to a particularly high strength of the rivet joint.Even the rivet mandrel 5, which is subjected to an axial force (which preferably has a large proportion of the tensile force Z) before the fracture at the predetermined breaking point 83 and the end of the setting process, can retain part of this axial force even after the setting process has been completed due to the form and force interlock provided by the locking mechanism in the locking groove 81 and the force interlock between the rivet dome head shaft 60 and the inner diameter of the shaft area 31 and / or a further force interlock between the locking shaft 82 and the setting head opening 30, and thus act as an axially pre-stressed rivet mandrel in the rivet joint, increasing the clamping force, even under additional loads (forces) that act on the rivet point during later operation.

[0120] By drawing the rivet head shank 60 (with a larger outer diameter) into the shaft area 31 (with a smaller inner diameter), the hollow rivet shank 4 expands and fills the fastening opening 103 in the workpiece 100, creating a force-fit connection. Additionally, a force-fit frictional connection R is established between the outer circumferential surface of the rivet head 5 in the area of ​​the rivet head shank 60 and

[0121] February 18, 2026 G 200 P 128 WO The inner circumferential surface of the hollow rivet shank 4 in the shaft area 31 is generated. This frictional fit R supports the transmission of the clamping force K into the rivet mandrel 5. An improvement in the connection between the rivet mandrel 5 and the hollow rivet shank 4 can be achieved by an additional surface structure 65 on the rivet mandrel 5, in particular on the rivet head shank 60. An example of such an (optional) surface structure 65 is shown in Figures 8a and 8b. There, several groove-shaped teeth 66 are embossed in the circumferential direction on the outer circumference of the rivet head shaft 60, spaced apart from each other in the axial direction, wherein the teeth 66 are directed in such a way that they do not impede the drawing in of the rivet head shaft 60 into the shaft area 31 of the hollow rivet shaft 4 in the direction of the tensile force Z and slide on the inner wall surface of the hollow rivet shaft 4.In contrast, if the movement were against the direction of the tensile force Z, the teeth 66 would scrape against the inner wall surface of the hollow rivet 4 and possibly dip into the inner wall surface.

[0122] An important advantage of the embodiment of the invention shown in Fig. 3 is that the position of the inner locking mechanism between the rivet mandrel 5 and the hollow rivet 2 is close to the force transmission point between the setting head 3 and the workpiece 100. This results in a direct and smooth force redirection. The more direct and smooth the force redirection, the better the force introduction and transmission properties. The rivet mandrel 5 can be additionally locked by force and / or form in the area below the rivet head 6, or it can support such a locking mechanism. Additionally, it is possible to apply adhesive (for additional support of the locking mechanism) and / or lubricant (for smoother insertion of the rivet head 60 into the shaft area 31), depending on the application, to the surface structure 65, shown here by way of example as serrations 66.

[0123] February 18, 2026 G 200 P 128 WO In the sectional view of the rivet head 6 and rivet head shank 60 according to Fig. 8b, a further feature optionally provided according to the invention for improving the connection between the rivet mandrel 5 and the hollow rivet shank 4 is proposed: an undercut 67 is formed on the rivet head shoulder 62 of the rivet head 6, against which the open end face 63 of the hollow rivet shank 4 engages. This ensures that the open end face 63 of the hollow rivet shank 4 is held particularly securely on the rivet head 6, by guiding the wall of the hollow rivet shank 4 in the area of ​​the end face 63 tightly against the rivet head shank 60 before the forming area 32 bends to form the setting head 33, and thus ensuring reliable force transmission in the axial direction.The undercut geometry generates radial forces acting continuously from the outside towards the axial central axis of the rivet boss 5 on the open end face of the hollow rivet 1, preventing relative movement between the open end face of the hollow rivet and the rivet boss head shoulder 62, i.e., the rivet mandrel 5 or the rivet mandrel head 6 does not slip into the hollow rivet 2. This feature can be realized together with and independently of the formation of the surface structure 65 also shown in Figs. 8a and 8b.

[0124] As shown in Fig. 4, the locking shoulder 35 can optionally be depicted as a chamfered or slotted shoulder 36 to facilitate the insertion of the locking shoulder material into the locking groove 81. This can be seen in the detailed enlargement of the locking shoulder 35 in Fig. 4. Furthermore, the locking head 80 can (preferably together with, but possibly also independently of, the feature described above) be formed as a chamfered or slotted shoulder 85 at the transition to the locking groove 81. This also facilitates the insertion of the locking shoulder material 35 into the locking groove 81. The chamfered or slotted shoulder 36 of the locking shoulder 35 and the chamfered or slotted shoulder 85 of the locking head 80 interlock.

[0125] February 18, 2026 G 200 P 128 WO then work particularly well together when setting the blind rivet and reinforce the internal locking of rivet mandrel 5 and hollow rivet 2 in the setting head 3.

[0126] Furthermore, according to the invention, an optional annular shoulder 37 projecting axially towards the free end 71 of the pull boss 7 around the setting head opening 30 can be provided on a surface of the setting head 3 facing away from the rivet head 6 (preferably radially oriented), onto which the counterforce G is applied when setting the blind rivet 1. This annular shoulder 37, more generally also referred to as a thickening, is pressed into the setting head by the application of the counterforce G during setting in the direction of the locking area 8 and thus also promotes the insertion of material from the locking shoulder 35 into the locking groove 81. These measures can also strengthen the internal locking in the area of ​​the setting head 3.

[0127] Furthermore, a separate deformable locking element 38 can be arranged in the shank region 4 of the hollow rivet 2 between the locking shoulder 35 of the hollow rivet 2 and the locking head 80 of the rivet boss, and / or wholly or partially in the setting head opening 30. This locking element engages in the locking groove 81 of the rivet boss 5 when the blind rivet 1 is set and is compressed there. This is shown in Fig. 5, and particularly in the enlarged detail. This embodiment can also be combined with all or some of the previously described embodiments to strengthen the internal locking mechanism, or implemented independently. The separate deformable locking element 38 can, for example, be designed as a metal ring.

[0128] Fig. 6a shows the blind rivet 1 described above in its initial state, in which the rivet mandrel 5 with the pull mandrel knurled 70 is pre-fixed in the setting head opening 30 of the hollow rivet 2 and the blind rivet 1 is inserted into the fastening opening 103 of a joining element 100. This shows the state before setting the

[0129] February 18, 2026 G 200 P 128 WOBlindniets 1, in which the axially projecting ring shoulder 37 is still formed on the setting head 3.

[0130] Figures 6b and 6c show the blind rivet 1 according to the invention after setting, in Figure 6b with a relatively thicker material 100 and in Figure 6c with a relatively thinner material 100. The forming area 32 of the hollow rivet 2 is contracted by the rivet head 6, forming the locking head 33, which rests against a surface of the material 100. Despite the different thicknesses of the material 100 in Figures 6b and 6c, the diameter of the formed locking head 33 is approximately comparable, resulting in a comparable force exerted by the locking head 33 on the material 100. This is advantageous because the setting properties and the joining properties of the blind rivet 1 are thus independent of the thickness of the material.

[0131] This is because, in both cases, the setting path of the blind rivet 1 is limited by the fact that the locking area 8 of the rivet head 5 is received into the setting head opening 30 and the locking head 80 rests against the locking shoulder 35 and / or is located wholly or partially within the setting head opening 30. Material from the locking shoulder 35 and / or the setting head 3 has been cold-formed (cold-drawn) into the locking groove 81. This achieves the positive-locking and, if applicable, also force-locking internal locking mechanism according to the invention, which has already been described.

[0132] The rivet mandrel 5 broke off at the predetermined breaking point 83 after setting, so that the area of ​​the pull boss 7 was removed. In addition, the ring shoulder 37 (see Fig. 6a) was pressed into the setting head 3 by the setting process and the application of the counterforce G. This ensures that the locking shaft 82 and the outer surface of the setting head 3 are essentially flush.

[0133] February 18, 2026 G 200 P 128 WO The rivet mandrel 5 can be designed as a solid bolt in the area of ​​the rivet head 6 and the rivet head shaft 60, which preferably adjoins the rivet head 6 directly, as shown in Fig. 7c. In this embodiment, the fastening opening 103 of the joining material 100 is completely filled when the blind rivet 1 is set. This results in a maximally stable rivet joint, which effectively absorbs shear forces between two joining materials 101, 102 (see Fig. 3).

[0134] In other embodiments, as shown in Figures 7a and 7b, the rivet mandrel 5 can have a cavity 68 extending axially at least through the rivet head 6, preferably concentric with the central axis of the rivet head 5. In the embodiment according to Figure 7b, the cavity 68 extends essentially only in the area of ​​the rivet head 6. This results in the fastening opening 103 still being essentially completely filled when a blind rivet 1 is set, with correspondingly high stability against shear forces. This (small) cavity 68 allows for a slight weight saving. Furthermore, the cavity can serve to hold the rivet head more securely in tools during manufacturing, for example, for joining the rivet mandrel 5 and the hollow rivet 2 in the initial tensile state shown in Figures 7a, 7b, and 7c.

[0135] In the embodiment according to Fig. 7a, the (large) cavity 68 extends through the rivet head 6 and substantially completely through the rivet head shank 60. In this embodiment, the rivet head shank 60 is also deformed, essentially compressed, when it is drawn into the shank area 31 of the hollow rivet 2. This allows for greater tolerances in the diameters of the fastening holes 103, because, in particular, slightly smaller diameters can be dynamically accommodated by deformation of the rivet head shank without causing damage to the workpiece 100 and / or jamming of the rivet head 5 in the

[0136] February 18, 2026 G 200 P 128 The hollow rivet 2 is inserted before the blind rivet 1 is fully set. However, the absorption of shear forces is lower in this embodiment. In practice, it is useful to have different embodiments of the blind rivet 1 available, with cavities 68 of varying sizes and without a cavity 68, depending on the application.

[0137] According to one embodiment, the rivet mandrel 5, in particular the rivet head shank 60, can have a variable cross-section 72 (Fig. 9a) and axially extending surface structures, e.g., indentations 73 (Fig. 9b), on its outer circumference. The variable cross-section 72 can form a polygonal structure. In the embodiment according to Fig. 9c, the variable cross-section 72 and the indentations 73 are superimposed. Above the side views in Figs. 9a, 9b, and 9c, corresponding sectional views through the rivet head shank 60 are shown. The variable cross-section 72, as shown, for example, in a polygonal structure, and / or the indentations 73 facilitate the insertion of the rivet head shank 60 into the shaft area 31 and counteract jamming. They also allow the introduction of lubricant and / or adhesive between the rivet mandrel 5 and the hollow rivet 2.Furthermore, they enable tolerance compensation at fastening openings 103 in the joining material 100 through increased variability in the displacement of the displaced material.

[0138] In one embodiment, the hollow rivet 2 can have axially extending surface structures, e.g., indentations 39, 40, on the inner circumferential surface (Fig. 10a) or the outer circumferential surface (Fig. 10b) or on both the inner and outer circumferential surfaces (Fig. 10c) of the hollow rivet in the shank region 31. These structures facilitate insertion and can strengthen a force-fit connection and / or contact in sections. Fig. 10d shows an embodiment with a variable cross-section 41 (polygonal structure) on the inner circumferential surface and (independently thereof) an annular shoulder 37 (thickening) on ​​the setting head 3. This feature can also be implemented in the same way in the embodiments of Figs. 10a to 10c. Above the side views in Figs. 10a to 10c,

[0139] February 18, 2026 G 200 P 128 WO10d shows corresponding sectional views through the shank area 31. These features can also contribute to tolerance compensation in the individual components of the blind rivet 1 and the riveting point.

[0140] According to one embodiment, the hollow rivet 2 of the blind rivet 1 can have different areas 42, 43 of varying stiffness in the forming area 32 and optionally (at least partially) also in the shank area 31. These areas can be created section by section, for example, by embossing into the outer circumferential surface of the hollow rivet 2 in the forming area 32 and, if necessary, also in the shank area 31. The wall thickness of the hollow rivet 2 can vary in the different areas 42, 43, particularly in the axial direction.

[0141] In the example shown here, the first area 42 forms an ascending ramp in the axial direction, extending from the open end face 63 of the hollow rivet 2 towards the setting head 3 (Fig. 11b), and the second area 43 forms a descending ramp in this axial direction (Fig. 11c). Deformation of the forming area 32 by tension on the rivet mandrel 5 or the draw mandrel 7 in this axial direction (i.e., in the example shown here, in the direction of the tensile force Z) occurs in the case of free deformation and / or smaller clamping lengths within the clamping area in the region of the deepest indentation in the area of ​​the ramp (i.e., the thinnest wall thickness of the hollow rivet 2). In the embodiment according to Fig. 11d, a first ramp 42 and a second ramp 43 are arranged one after the other in this axial direction in the forming area 32. This defines and specifies the upper and lower forming points for forming the locking head 33.

[0142] From a certain thickness of the clamping length, buckling of the forming area 32 at an opening edge of the joining material 100 can also begin, if the area around the deepest indentation of the sloping ramp 43 facing the setting head 3 is still within the opening 103 of the joining material 100.

[0143] February 18, 2026 G 200 P 128 WOFig. 11e shows the embodiment according to Fig. 11 d with an additional axial surface structure, e.g. indentation 40, on the outer circumferential surface of the hollow rivet 2 in the shank area 31.

[0144] Fig. 11a shows a blind rivet 1 with a hollow rivet 2 without indentations or structuring on the outer circumference of the hollow rivet according to an embodiment of the invention.

[0145] The embodiments of rivet dome 5 and hollow rivet 2 described above can be combined with each other and / or with other described embodiments of the blind rivet 1 in a suitable manner according to the invention, even if such embodiments are not explicitly shown and / or illustrated.

[0146] Reference symbol list:

[0147] 1 blind rivet

[0148] 2 hollow rivets

[0149] 3 Set head

[0150] 4 hollow rivet

[0151] 5 rivet mandrel

[0152] 6 rivet head

[0153] 7. Pull mandrel (also called rivet dome)

[0154] 8 Locking area

[0155] 9 Introduction phase

[0156] 30 Setting head opening

[0157] 31 shaft area

[0158] 32 Forming area

[0159] 33 Locking head

[0160] 34 Transition area

[0161] February 18, 2026 G 200 P 128 WO35 Locking paragraph

[0162] 36 Beveled or slotted shoulder of the locking shoulder 37 Ring shoulder (thickening)

[0163] 38 separate deformable locking elements

[0164] 39 axial indentation (surface structure) on the inner circumferential surface of the hollow rivet

[0165] 40 axial indentations (surface structure) on the outer circumferential surface of the hollow rivet

[0166] 41 variable cross-section on the inner circumferential surface of the hollow rivet

[0167] 42 first area of ​​varying stiffness (first ramp)

[0168] 43 Second area of ​​varying stiffness (second ramp)

[0169] 60 rivet mandrel head shaft

[0170] 61 Rivet head flange

[0171] 62 Rivet head heel

[0172] 63 open front

[0173] 64 Entrance slope

[0174] 65 Surface structure

[0175] 66 groove-shaped prongs

[0176] 67 Undercut

[0177] 68 Cavity

[0178] 70 mandrel knurled

[0179] 71 free end of the train dome

[0180] 72 variable cross-section of the rivet dome head shaft

[0181] 73 axial indentation (surface structure) of the rivet dome head shaft

[0182] 80 Locking head

[0183] 81 Locking groove

[0184] 82 Locking shaft

[0185] 83 Breakaway point

[0186] February 18, 2026 G 200 P 128 WO84 draw mandrel bevel

[0187] 85 beveled or slotted shoulder of the locking head

[0188] 100 joining material or fastening material

[0189] 101 first joining material

[0190] 102 second joining material

[0191] 103 Opening / Mounting opening

[0192] D1 Head shaft diameter

[0193] D2 locking head diameter

[0194] D3 locking shaft diameter

[0195] D4 pull dome diameter

[0196] Z tractive force

[0197] G Counterforce

[0198] T Separating force

[0199] K clamping force

[0200] R Friction closure

[0201] February 18, 2026 G 200 P 128 WO

Claims

Claims:

1. Blind rivet with a hollow rivet (2) and a rivet mandrel (5) guided in the hollow rivet (2), wherein the hollow rivet (2) has a setting head (3) with an axial setting head opening (30) and a hollow rivet shank (4) extending axially to the setting head (3), wherein the rivet mandrel (5) has a rivet dome head (6), a rivet dome head shaft (60) extending axially from the rivet dome head (6), a pull mandrel (7) extending axially and a locking area (8) formed between the rivet dome head shaft (60) and the pull mandrel (7), wherein the mandrel (7) is guided in the setting head opening (30) so as to be movable in the axial direction and the setting head (3) and the rivet dome head (6) are arranged in the axial direction on different sides of the hollow rivet shank (4), wherein a head shank diameter (D1) of the rivet dome head shank (60) is larger than an inner diameter in a shank section (31) of the hollow rivet (2) adjoining the setting head (3) and is dimensioned such that the rivet dome head shank (60) can be drawn into the shank section (31) of the hollow rivet (2) when an axial tensile force (Z) is applied to the draw mandrel (7) under cold deformation of the shank section (31) and / or rivet dome head shank (60) due to radial pressure until the locking area (8) of the rivet dome (5) is positioned on and / or in the setting head (3) of the hollow rivet (2), characterized by the fact that February 18, 2026 G 200 P 128 WO or hollow rivet (2) adjoining the shank area (31) on the side facing away from the setting head (3) has a forming area (32) for forming a closing head (33), wherein a forming stiffness of the forming area (32) is less than a forming stiffness of the shank area (31), and The rivet dome head (6) has a rivet dome head flange (61) at the end of the rivet dome head shaft (60) facing away from the locking area (8), which projects radially outwards from the rivet dome head shaft (60) with a rivet dome head shoulder (62) and engages an open end face (63) of the forming area (32) of the hollow rivet shaft (4) during an axial movement of the rivet dome (5) in order to form the locking head (33) by deforming the forming area (32) when the tensile force (Z) is further applied to the mandrel (7).

2. Blind rivet according to claim 1, characterized in that the locking area (8) of the rivet dome (5) has a locking head (80), wherein a locking head diameter (D2) is smaller than the inner diameter in the shank area (31) of the hollow rivet (2) and is larger than an inner diameter of the setting head opening (30) which is formed in the setting head (3) on a locking shoulder (35) adjoining the shank area (31) of the hollow rivet (2).

3. Blind rivet according to claim 1 or 2, characterized in that an axial length of the locking area (8) of the rivet dome (5) corresponds to an axial length of the setting head opening (30).

4. Blind rivet according to one of claims 2 or 3, characterized in that a locking groove (81) is formed in the locking area (8) following the locking head (80). February 18, 2026 G 200 P 128 WO5. Blind rivet according to claim 4, characterized in that the locking groove (81) of the rivet boss (5) is arranged in a radial plane which runs within the joining material or fastening material (100) when the blind rivet (1) is set.

6. Blind rivet according to one of the preceding claims, characterized in that the setting head (3) has an annular shoulder (37) projecting axially outwards in the direction of the free end of the pull dome around the setting head opening (30).

7. Blind rivet according to one of the preceding claims, characterized in that a mechanical locking mechanism is provided at the end of the locking area (8) facing the mandrel (7), which locks the mandrel (5) in the setting head after the blind rivet (1) has been set.

8. Blind rivet according to one of the preceding claims, characterized in that an undercut (67) on the rivet head shoulder (62) and / or a groove engaging in the rivet head (6) and / or the rivet head shaft (60) is formed on the rivet head shoulder (62) at the transition from the rivet head (6) to the rivet head shaft (60).

9. Blind rivet according to one of the preceding claims, characterized in that the rivet mandrel (5) has a cavity (68) extending axially at least through the rivet dome head (6).

10. Blind rivet according to claim 9, characterized in that the cavity (68) extends partially or completely through the rivet head shaft (60).

11. Blind rivet according to a preceding claim, characterized in that a surface structure (65) is incorporated in an outer circumferential area of ​​the rivet head shaft (60). February 18, 2026 G 200 P 128 WO12. Blind rivet according to one of the preceding claims, characterized in that adhesive is provided at least partially on the rivet dome head shank (60) of the rivet dome (5).

13. Blind rivet according to one of the preceding claims, characterized in that the hollow rivet shank (4) has different areas (42, 43) of different stiffness, particularly in the forming area (32).

14. Blind rivet according to one of the preceding claims, characterized in that the hollow rivet shank (4) has surface structures extending axially in the direction on an outer circumference and / or on an inner circumference, in particular indentations (39, 40), and / or a variable cross-section (41).

15. Blind rivet according to one of the preceding claims, characterized in that the rivet head shank (60) has surface structures extending axially on an outer circumference, in particular indentations (73), and / or a variable cross-section (72). February 18, 2026 G 200 P 128 WO

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