Blind rivet nut for a screw connection, associated arrangement and manufacturing process of a blind rivet nut

Abstract

Blind rivet nut (1) for a screw connection between a support component and a fastening component, comprising: a. a sleeve-shaped shaft (10) with an internal thread (16) that can be inserted into a fastening hole of the support component, a fastening flange (20) at a first end and a folding zone (12) that can be folded into a compression bead and supported on opposite sides of the support component, wherein b. the fastening flange (20) has a knurling (22) on a radially outer side as well as axial projections (24) on the side of the fastening flange (20) facing the shaft and axial projections (26) on the side of the fastening flange (20) facing away from the shaft, each of which is arranged immediately adjacent to the radial outer side.

Description

Field of invention

[0001] The present invention relates to a blind rivet nut for a screw connection between a support component and a fastening component, an arrangement consisting of a support component and a blind rivet nut arranged therein, and a manufacturing method for a blind rivet nut. Background of the invention

[0002] Blind rivet nuts are known in a variety of ways in the prior art. EP 1 279 839 A2 and EP 1 710 454 A1 are examples. EP 1 279 839 A2 describes a screw-blind rivet connection arrangement for joining a lower component to an upper component. The screw-blind rivet connection arrangement consists of a screw and a nut-like blind rivet, which can be inserted into mounting holes of the two components and screwed together to create the connection. The blind rivet, which is made of an elastically deformable material, has a sleeve-shaped lower part and a sleeve-shaped upper part, the wall thickness of which is dimensioned such that the lower part has high stiffness and the upper part high flexibility, and which are integrally connected by a shoulder-shaped transition point of reduced wall thickness.In this way, when the screw is screwed into the lower part of the blind rivet, the wall of the upper part rolls down on the outer surface of the lower part and is thereby folded into a rivet bead that lies against the outer surface of the lower part to prevent the connection from loosening.

[0003] A blind rivet for a screw connection between a support member and a fastening member is also described in EP 1 710 454 A1. The blind rivet consists of an elastic outer body with a sleeve-shaped shank that can be inserted into a fastening hole in the support member. The shank has a fastening flange and a folding zone that can be folded into a compression bead, which can be supported on opposite sides of the support member. The blind rivet also has a metallic bushing located inside the outer body. Furthermore, an anti-rotation feature is provided for the elastic outer body to prevent twisting.

[0004] DE 10 2011 076 069 A1 describes a countersunk nut for embedding in a support. The countersunk nut has a shank with a head at one end and is axially divided into a threaded section for receiving a fastener and a recessed section adjacent to the head, which is designed to form a bead. The head is formed by a plurality of radial, pointed teeth, each with a progressive rib for connecting to the rest of the shank. The rib is inclined such that the formation of the bead is accompanied by the axial insertion of the head into the support until the head is integrally countersunk into the support without damaging it.

[0005] An arrangement consisting of a crimped nut and a part with a surface providing a hole into which the nut is crimped is described in EP 0 691 480 A1. The nut has an axis of symmetry and is formed by a threaded shank terminating in a head with a larger diameter than the shank. The head has a truncated lateral surface in contact with the surface defining the hole. The truncated lateral head surface forms an inner head surface perpendicular to the axis of the nut from the side of the shank. The truncated lateral head surface forms a cylindrical lateral surface from the side facing away from the shank. There are radial notches extending from the inner surface of the head. The width of the notch is less than half the radial dimension of the inner surface.

[0006] Finally, DE 697 11 285 T2 describes a crimp nut with an embedded head. The crimp nut comprises a metal body with a shank having a polygonal cross-section, which is extended by a base with a cylindrical inner opening that is threaded to form an internal thread. The shank is designed to engage with a receptacle for a metal retaining element. Furthermore, the crimp nut includes a collar located in the upper part of the shank, forming a thin head of the nut. The height of the collar is small compared to that of the shank. The wall thickness of the shank is less than that of the base to allow the formation of a retaining bead when the nut is crimped into the receptacle of the metal retaining element, which has a shape matching the polygonal shank.The underside of the collar features multiple toothed elements arranged at regular intervals around the head. Each toothed element is designed as a prismatic tooth that, during crimping, bores into the metal of the retaining element and pushes the excess metal into the cavities provided between successive teeth of the collar, ensuring that the nut head is fully seated and crimped into the receptacle. The inclined outer edge of each tooth of the collar forms a first acute angle of approximately 30 to 45° with the vertical plane parallel to the axis of the nut.

[0007] None of these documents addresses the problem of establishing an electrical contact between the component in which the blind rivet nut is attached and another component via the blind rivet nut.

[0008] Approaches to this can be found in EP 2 549 592 B1. The insert described here has an electrically conductive body with a head located at one longitudinal end of a cylinder of the body, the body being covered with a protective layer. The cylinder extends from a first surface of the head. The body comprises points distributed on the plane of the circumference of a second surface of the head. Each point has a tip connected to the second surface of the head by an associated edge, the inclination of the edge with respect to a horizontal plane defined by the second surface of the head being between 45 degrees and 60 degrees.

[0009] Despite the points provided on the top of the head of this blind rivet nut, establishing a reliable electrical contact via the insert is not feasible. This is due, among other things, to the fact that the points often lack the necessary hardness to penetrate the coating of the corresponding component to create the electrical contact.

[0010] The object of the present invention is therefore to provide a blind rivet nut for a screw connection which, compared to the prior art, enables a reliable electrical contact between two components. It is also an object of the present invention to provide a corresponding manufacturing process for such a blind rivet nut. Summary of the invention

[0011] The above problem is solved by a blind rivet nut for a screw connection according to independent claim 1, an arrangement according to independent claim 9, and a manufacturing method according to independent claim 12. Advantageous embodiments and further developments will become apparent from the following description, the drawings, and the pending claims.

[0012] A blind rivet nut according to the invention for a screw connection between a support component and a fastening component comprises: a sleeve-shaped shank with an internal thread that can be inserted into a fastening hole of the support component, a fastening flange at a first end, and a folding zone that can be folded into a compression bead and supported on opposite sides of the support component. The fastening flange has knurling on a radially outer side and axial projections on the side of the fastening flange facing the shank and / or axial projections on the side facing away from the shank, which are arranged immediately adjacent to the radial outer surface. This allows a coating of the support component and / or the fastening component to be penetrated by means of the axial projections, and makes it easier to establish an electrical contact using the blind rivet nut compared to the prior art.

[0013] The blind rivet nut according to the invention differs from the known blind rivet nuts described above primarily in the presence of knurling on the radial outer surface of the mounting flange in combination with axial projections on the upper and / or lower surface of the mounting flange. These design features result from the modified manufacturing process compared to known blind rivet nuts. For better understanding, the manufacturing method of the blind rivet nut according to the invention is explained below.

[0014] First, a material for the blind rivet nut is machined either by cold forming or turning, as is known. After this step, the blind rivet nut has a sleeve-shaped shank with an internal thread. The shank, which is later inserted into the mounting hole of the supporting component, already includes the mounting flange at one end and the folding zone that can be folded into a crimp bead. The crimp zone preferably also already has the desired design, for example, knurling. When the blind rivet nut is subsequently used, the mounting flange and the crimp bead are supported on opposite sides of the supporting component.

[0015] In a separate, subsequent step, the blind rivet nut undergoes further cold forming. Here, the mounting flange is machined so that it has knurling on a radially outer side, as well as axial projections on the side of the mounting flange facing the shank and / or on the side facing away from the shank, which are arranged immediately adjacent to the radial outer surface.

[0016] This cold forming step, separate from the conventional manufacturing process and occurring downstream, along with the provision of knurling and axial projections, allows for reliable penetration of a coating on a support component and / or a fastening component via the axial projections when using the blind rivet nut, thus enabling electrical contact via the blind rivet nut. The knurling and axial projections are preferably produced simultaneously in a single step, particularly with a suitable knurling tool.

[0017] When used, the blind rivet nut is inserted into the mounting hole in the substrate. It is then secured by screwing a screw with an external thread matching the internal thread of the blind rivet nut into it. This folds the crimped section and forms the crimp bead on the side of the substrate opposite the mounting flange. This securely holds the blind rivet nut in the substrate. If the blind rivet nut has axial projections on the side of the mounting flange facing the shank, these projections will have penetrated the substrate's coating, allowing electrical contact to be established between the blind rivet nut and a mounting component, such as a component to be mounted on the substrate or a pole piece to be attached to the blind rivet nut.

[0018] The blind rivet nut according to the invention is therefore a blind rivet nut ready for sale and distribution, which has completely undergone the corresponding manufacturing process.

[0019] An advantage of the blind rivet nut according to the invention is that the axial projections are provided directly adjacent to the knurling on the mounting flange on at least one of the two sides of the mounting flange. Due to the arrangement of the axial projections on the side of the mounting flange facing the shank, directly adjacent to the radial outer surface, the coating of the support component is reliably pierced at a distance from the mounting hole in the support component, and an electrical contact is established by means of the blind rivet nut. Thus, the electrical contact can be established independently of the mounting hole in the support component, so that the mounting hole does not need to be separately machined or modified either before or during the insertion of the blind rivet nut.

[0020] Similarly, a coating on a component subsequently mounted on the carrier component can be reliably pierced by means of the axial projections located immediately adjacent to the radial outer surface of the mounting flange, thus establishing an electrical contact using the blind rivet nut. It is also preferred that the axial projections are present on both sides of the mounting flange. In this case, it is unnecessary to select a blind rivet nut with the projections on the required side, minimizing the risk of incorrect selection.

[0021] In a preferred embodiment of the blind rivet nut, the knurling and axial projections are produced by cold forming, particularly without subsequent heat treatment. This results in a modified microstructure of the material in the knurling and axial projection area compared to the rest of the blind rivet nut, especially in the area near the shank of the mounting flange. Preferably, the term "area near the shank of the mounting flange" refers to a portion of the radial or lateral extent of the mounting flange that is less than half of the total radial or lateral extent of the mounting flange, preferably less than one-third, and particularly preferably less than one-quarter, measured from the edge of the through-hole. Cold forming is the plastic deformation of metals below their recrystallization temperature. The work hardening that occurs during this process leads to a continuous increase in material strength.Cold working refers to the increase in dislocation density due to plastic deformation, i.e., the total length of all dislocation lines per unit volume. This increases the probability that dislocations will impede each other's movement. Consequently, a greater stress is required for further deformation, which manifests as an increase in yield strength and tensile strength. In other words, cold forming stretches the microstructure of metals in the direction of deformation, thus increasing strength. However, deformability decreases, a process known as cold working. Ultimately, this means that cold forming causes a change in the material's microstructure, which is visible in a micrograph.

[0022] If the increase in strength is undesirable, it must be reduced again by subsequent heat treatment. Such heat treatment, also known as annealing, particularly recrystallization annealing, is carried out according to the prior art after the blind rivet nut has been formed into a shape that exhibits all the desired geometric features. This is intended to prevent the material of the blind rivet nut from being too brittle and developing cracks during fastening in the supporting component, which would prevent the blind rivet nut from no longer meeting the requirements for pull-out force or similar properties.

[0023] According to the preferred embodiment, cold forming to introduce the knurling and axial projections takes place after such a heat treatment. In this way, the axial projections exhibit increased strength, so that a coating on the carrier component can be reliably penetrated by the blind rivet nut to establish an electrical contact. As already indicated above, the term work hardening refers to an increase in the yield strength of the material as well as its fracture toughness, while the elongation at break decreases. The increased strength is therefore particularly evident in the increased fracture toughness.

[0024] In an advantageous embodiment, the first Vickers hardness H1 and the second Vickers hardness H2 of the blind rivet nut H1 ≥ f H2, wherein the first and second Vickers hardnesses are measured using HV 0.3, the first Vickers hardness H1 is determined on a side of the mounting flange facing away from the shank immediately adjacent to the knurling, the second Vickers hardness H2 is determined on a side of the mounting flange facing away from the shank adjacent to a through-hole, and the factor f is at least 1.2, preferably at least 1.4, and particularly preferably at least 1.55.

[0025] Instead of determining the tensile strength of different areas of the blind rivet nut to demonstrate work hardening, it is equally preferred to demonstrate work hardening using the Vickers hardness test according to DIN EN ISO 6507, the content of which is fully incorporated herein by reference, particularly with regard to the test according to HV 0.3.

[0026] To verify the differences, the first Vickers hardness is measured immediately adjacent to the knurling on a side of the mounting flange facing away from the shank. According to a preferred embodiment, "immediately adjacent to the knurling" means that a first measurement point for the first Vickers hardness is located on a line connecting the valleys of the knurling or is positioned radially or laterally further outward in the direction of the knurling peaks. In particular, if the knurling consists of a sequence of deep and shallow valleys, for example, alternating deep and shallow valleys, the line connecting the valleys is formed such that the adjacent deep valleys are connected to each other, i.e., omitting the shallower valleys.

[0027] For comparison, the second Vickers hardness is also measured in an area adjacent to a through-hole of the blind rivet nut on the side of the mounting flange facing away from the shank, particularly in an area close to the shank. Preferably, "adjacent" means that a second measuring point for the second Vickers hardness is located in a region of the radial or lateral extent of the mounting flange that is less than ½ of the total radial or lateral extent of the mounting flange, preferably less than 1 / 3, and particularly preferably less than ¼, measured from the edge of the through-hole.

[0028] The test is carried out using the test conditions of the Vickers hardness test according to HV 0.3, wherein the first Vickers hardness H1 measured in this way is at least 1.2 times the measured second Vickers hardness H2, particularly preferably at least 1.4 times and especially preferably at least 1.55 times.

[0029] In a further preferred embodiment of the blind rivet nut, the knurling and / or axial projections exhibit a cold-forming-specific microstructure, recognizable via a micrograph, after or without prior heat treatment, in comparison to the microstructure of the fastening flange, particularly in a region near the shank. Regarding the term "region near the shank," reference is made to the above explanations, which apply analogously here. Instead of, or in addition to, the Vickers hardness test, the modified microstructure is verified here by means of micrographs.

[0030] As explained above, the term "thermal treatment" refers, for example, to annealing, particularly recrystallization annealing, after the initial cold forming or turning to produce the shaft with mounting flange. In this context, recrystallization annealing refers to annealing without phase change at a temperature within the recrystallization range after cold forming. Recrystallization annealing is primarily used after and, if necessary, between the individual forming stages in the cold rolling or drawing of sheets and wires. Recrystallization annealing restores the original microstructure. Therefore, a difference is visible in the micrograph between the areas that were cold-formed after annealing and the areas that were cold-formed before annealing but are no longer cold-formed afterward.

[0031] Advantageously, the axial projections of the blind rivet nut are larger than 20 µm, preferably larger than 30 µm, and particularly preferably larger than 40 µm, relative to a given surface of the mounting flange, especially in a region near the shank. Regarding the term "region near the shank," reference is made to the above explanations, which apply analogously to this embodiment. With axial projections of this size, the coatings of, for example, the carrier component can be penetrated particularly reliably, thus enabling a particularly effective electrical contact.

[0032] In a preferred embodiment of the blind rivet nut, it is made of one of the following materials: steel, stainless steel, aluminum, or brass. These materials are particularly easy to work with and also exhibit good electrical conductivity to enable electrical contact via the blind rivet nut.

[0033] It is also preferred that the mounting flange of the blind rivet nut has a thickness of at least 0.5 mm, preferably at least 0.75 mm, and particularly preferably 1.0 mm. This thickness makes it particularly reliable to ensure that the knurling tool can simultaneously produce not only the knurling but also the axial projections in the mounting flange.

[0034] An arrangement according to the invention consists of a support component and a blind rivet nut according to the invention arranged therein. With regard to the resulting advantages, reference is made to the above descriptions of the blind rivet nut according to the invention in order to avoid repetition.

[0035] In a preferred embodiment of the arrangement, it further comprises a fastening component that is connected to the support component by means of the blind rivet nut. The fastening component is, for example, a pole shoe. Alternatively, the fastening component is a component that is to be arranged on the support component.

[0036] In a further preferred embodiment of the arrangement, the support component and / or the fastening component is therefore one of the following: aluminum with an oxide layer, steel with a coating, in particular with a cathodic dip coating (e-coating) or an electroplated coating, or carbon fiber reinforced plastic (CFRP). If the fastening component is one of those listed above, the fastening component is preferably a component that engages with the side of the fastening flange facing away from the shaft, such that axial projections present there pierce the corresponding coating.

[0037] A manufacturing method according to the invention for a blind rivet nut according to the invention comprises the following steps: cold forming of a material for the blind rivet nut, such that the blind rivet nut comprises a sleeve-shaped shank with an internal thread which can be inserted into a mounting hole of the support component and has a mounting flange at a first end and a folding zone which can be folded into a compression bead and which can be supported on opposite sides of the support component, or turning of the material for the blind rivet nut, such that the blind rivet nut comprises a sleeve-shaped shank with an internal thread which can be inserted into a mounting hole of the support component and has a mounting flange at a first end and a folding zone which can be folded into a compression bead and which can be supported on opposite sides of the support component, followed by cold forming of the blind rivet nut.so that the mounting flange has knurling on a radially outer side, as well as axial projections on the side facing the shaft and / or axial projections on the side of the mounting flange facing away from the shaft, which are arranged immediately adjacent to the radial outer surface. This makes it possible to penetrate a coating of a support component and / or a mounting component by means of the axial projections and to establish an electrical contact via the blind rivet nut more easily compared to the prior art. The blind rivet nut according to the invention can therefore be manufactured using the manufacturing method according to the invention, so that, in view of the resulting advantages, reference is made to the above explanations to avoid repetition.

[0038] In a preferred embodiment of the manufacturing process, the process includes the further step of annealing the blind rivet nut prior to its cold forming. This annealing takes place after the initial cold forming or turning and before the cold forming of the blind rivet nut to produce the knurling and axial projections on the mounting flange. The subsequent cold forming, particularly the recrystallization annealing, to produce the knurling and axial projections allows for the creation of exceptionally hard projections capable of penetrating the coating of the carrier component and / or the mounting component. Reference is also made to the corresponding explanations above in this context.

[0039] In a further advantageous embodiment of the manufacturing process, the knurling and the axial projections were produced by cold forming, in particular without subsequent heat treatment, so that a modified microstructure of the material exists in the area of ​​the knurling and the axial projections compared to the rest of the blind rivet nut, especially in a shank-adjacent area of ​​the fastening flange. Reference is also made to the corresponding explanations above regarding the resulting advantages.

[0040] It is further preferred that, after cold forming, the blind rivet nut exhibits a cold-forming-specific microstructure of the knurling and / or axial projections, recognizable via a micrograph, after or without prior heat treatment, in comparison to the microstructure of the fastening flange, particularly in a region near the shank. Reference is also made to the corresponding explanations above.

[0041] Finally, it is preferred that the material for the blind rivet nut is selected from one of the following during the manufacturing process: steel, stainless steel, aluminum or brass.

[0042] The advantages of this material selection have already been explained in the discussion of the blind rivet nut according to the invention, so reference is made to that section. List of characters

[0043] The present invention is described in detail below with reference to the drawings. Identical reference numerals in the drawings denote identical components and / or elements. The drawings show: Fig. 1 a first perspective view of an embodiment of the blind rivet nut according to the invention, Fig. 2 a second perspective view of the embodiment of the blind rivet nut according to the invention Fig. 1, Fig. 3 a third perspective view of the embodiment of the blind rivet nut according to the invention Fig. 1, Fig. 4 a flowchart of an embodiment of a manufacturing process according to the invention for a blind rivet nut, Fig. 5 A first micrograph of an embodiment of the blind rivet nut taken in a shaft-adjacent area of ​​the mounting flange, Fig. 6 a second micrograph of an embodiment of the blind rivet nut taken in an edge area of ​​the mounting flange and Fig. 7 An enlarged perspective view of the mounting flange to show the possible measurement points for a first Vickers hardness and a second Vickers hardness. Detailed description of preferred embodiments

[0044] The following and with reference to the Fig. 1 to Fig. 3 describes an embodiment of the blind rivet nut according to the invention. 1 explained. The blind rivet nut 1 includes a sleeve-shaped shaft 10 with an internal thread 16 and a mounting flange 20 When using the blind rivet nut 1 is the shaft 10 It can be inserted into a mounting hole of a supporting component. The blind rivet nut 1It is therefore used for a bolted connection between the support component and a fastening component. The support component is one of the following: aluminum with an oxide layer, steel with a coating, in particular with cathodic dip coating (e-coating) or an electroplated coating, or carbon fiber reinforced plastic (CFRP). The fastening component is, for example, a component that is to be mounted on the support component or a pole shoe that is to be mounted on the blind rivet nut.

[0045] The blind rivet nut 1 It is made from one of the following materials: steel, stainless steel, aluminum, or brass. These materials are particularly easy to work with and also exhibit good electrical conductivity, ensuring an electrical contact via the blind rivet nut during use. 1 to be able to produce them.

[0046] The sleeve-shaped shaft 10indicates the mounting flange 20 at a first end and a folding zone that can be folded into a compression bead 12 on. The mounting flange 20 and those after the blind rivet nut has been fastened 1 The resulting compression bulge later rests against opposite sides of the supporting component. In the illustrated embodiment, the sleeve-shaped shaft has... 10 adjacent to the mounting flange 20 a knurling 14 on.

[0047] Furthermore, the mounting flange includes 20 A knurling on a radially outer side 22 as well as axial projections 24 on the shaft 10 facing side and axial projections 26 on the shaft 10 far side of the mounting flange 20 The axial projections 24 , 26 are immediately adjacent to the radial outer side of the mounting flange 20are arranged. In particular by means of the axial projections. 24 , 26 is when using the blind rivet nut 1 a coating of the support component and / or the fastening component is pierceable and an electrical contact is made by means of the blind rivet nut 1 manufacturable.

[0048] The axial projections 24 , 26 the blind rivet nut 1 are larger than 20 µm, preferably larger than 30 µm and particularly preferably larger than 40 µm with respect to a respective surface of the mounting flange. 20 , particularly in a shaft-adjacent area. Preferably, the term shaft-adjacent area refers to the mounting flange. 20 an area of ​​the radial or lateral extent of the mounting flange 20 , which is less than ½ of the total radial or lateral extent of the mounting flange 20, preferably less than 1 / 3 and particularly preferably less than 1 / 4 measured from the edge of a through-opening 32 the blind rivet nut 1 . With the axial projections 24 , 26 At this scale, coatings, for example on the carrier component, can be penetrated particularly reliably, so that an electrical contact can be established particularly effectively.

[0049] The mounting flange 20 the blind rivet nut 1 It has a thickness of at least 0.5 mm, preferably at least 0.75 mm, and particularly preferably 1.0 mm. Due to this thickness of the mounting flange... 20 is it in the manufacture of the blind rivet nut 1 It is particularly process-reliable to ensure that not only the knurling is achieved using a knurling tool. 22 on the mounting flange 20 but also the axial projections 24 , 26 in the mounting flange20 are producible. This will be explained later along with the manufacturing process.

[0050] Especially when the fastening component is a part that is to be mounted on the supporting component, the fastening component may, for example, consist of: aluminum with an oxide layer, steel with a coating, in particular with cathodic dip coating (e-coating) or an electroplated coating, or carbon fiber reinforced plastic (CFRP). In this case, the fastening component is therefore a part that, when using the blind rivet nut, 1 with a shaft 10 far side of the mounting flange 20 is in engagement, so that existing axial protrusions there 26 pierce the corresponding coating.

[0051] When used, the blind rivet nut 1inserted into the mounting hole in the support component. Fastening in the support component is achieved by using a screw with an internal thread. 16 the blind rivet nut 1 matching external thread into the blind rivet nut 1 It is screwed in. The folding zone is then... 12 folded and the compression bead is placed on the mounting flange 20 The opposite side of the supporting component is formed in this way. The blind rivet nut is thus created. 1 now securely held in the supporting component. If the blind rivet nut 1 the axial projections 24 on the side of the mounting flange facing the shaft 20 If this indicates that they have pierced a coating of the support component, allowing an electrical contact via the blind rivet nut. 1 can be manufactured as a fastening component, such as a pole shoe.

[0052] One advantage of the blind rivet nut according to the invention 1 This means that the axial projections are immediately adjacent to the knurling. 22 on the mounting flange 20 on at least one of the two sides of the mounting flange 20 are provided. This allows the electrical contact to be established independently of the design of the mounting hole in the support component. Furthermore, due to the axial projections 24 on the side of the mounting flange facing the shaft 20 The coating of the support component is reliably pierced at a distance from the mounting hole in the support component, and an electrical contact is made by means of the blind rivet nut. 1 be manufactured.

[0053] Similarly, a coating of a component subsequently placed on the support component, which has a side of the mounting flange facing away from the shaft, can 20in the system, by means of the axial projections located there immediately adjacent to the knurling. 26 reliably pierced and an electrical contact made here by means of the blind rivet nut 1 can be manufactured. Additionally, and as shown in the embodiments, the axial projections can be 24 , 26 on both sides of the mounting flange 20 must be present. In this case, it is not necessary to pay attention to which component an electrical contact is to be made with, and the manufacturing process is simplified.

[0054] To better understand the special features of the blind rivet nut 1 The following additional reference is made to the flowchart according to Fig. 4. Reference is made. In a first step, the material for the blind rivet nut is selected. 1 first either by means of cold forming (step A1 ) or by turning (step A2) processed. After this step, the blind rivet nut indicates 1 the sleeve-shaped shaft 10 with internal thread 16 on. The shaft also includes 10 already the mounting flange 20 at a first end and the folding zone which can be folded into a compression bead 12 Furthermore, in this step the knurling was 22 on the shaft 10 provided.

[0055] Cold forming is the plastic deformation of metals below their recrystallization temperature. During this process, the microstructure of the metal is stretched in the direction of deformation, thus increasing its strength. The resulting work hardening leads to a continuous increase in the material's strength. However, its ductility decreases. Work hardening refers to the increase in dislocation density due to plastic deformation, i.e., the total length of all dislocation lines per unit volume. This increases the probability that dislocations will impede each other's movement. Consequently, a greater stress is required for further deformation, which manifests as an increase in yield strength and overall strength. Ultimately, this means that cold forming alters the microstructure of the material, a change that is visible in a micrograph.

[0056] If the increase in strength is undesirable, it must be reduced again by subsequent heat treatment. Such heat treatment is carried out according to the following steps. A1 or A2 In the subsequent step C, the material is annealed, in particular recrystallization annealed. Recrystallization annealing is defined as annealing without phase change at a temperature within the recrystallization range after cold forming. Recrystallization annealing is primarily used after and, if necessary, between the individual forming stages in the cold rolling or drawing of sheets and wires. Recrystallization annealing restores the original microstructure. This is intended to prevent the material of the blind rivet nut from deteriorating. 1 is too brittle and develops cracks when fastened in a supporting component, so that the blind rivet nut 1would no longer meet the requirements for pull-out force or similar.

[0057] Only after the annealing in step C does a further cold forming of the blind rivet nut take place in a separate and subsequent step B. 1 . Here, the mounting flange is used. 20 machined so that it has a knurling on a radially outer side 22 as well as axial projections 24 on the shaft 10 facing side and axial projections 26 on the shaft 10 far side of the mounting flange 20 exhibits features that are located immediately adjacent to the radial outer surface.

[0058] In contrast to conventional manufacturing, the blind rivet nut according to the invention 1 cold forming to introduce the knurling 22 and the axial projections 24 , 26This occurs after a heat treatment, such as annealing, in particular recrystallization annealing. No further thermal treatment is planned thereafter.

[0059] In this way, the axial projections point 24 , 26 This results in increased strength. This is achieved through the separate cold forming step and the knurling. 22 and the axial projections 24 , 26 is when using the blind rivet nut 1 the coating of the support component and / or the fastening component by means of the axial projections 24 , 26 particularly reliable penetration and an electrical contact via the blind rivet nut 1 manufacturable. The knurling 22 as well as the axial projections 24 , 26 They are produced simultaneously in a single step, especially with a knurling tool. For example, the axial projections are 24 ,26 during the formation of the knurling 22 formed due to the knurling tool used.

[0060] Due to the formation of the knurling 22 as well as the axial projections 24 , 26 Cold forming without subsequent heat treatment results in an altered microstructure of the material in the knurling area. 22 as well as the axial projections 24 , 26 compared to the rest of the blind rivet nut 1 , especially in a shaft-adjacent area of ​​the mounting flange 20This altered microstructure is therefore visible in a micrograph. Thus, the manufacturing process can be traced using a micrograph. Due to the altered microstructure resulting from cold forming after annealing, a cold-forming-specific microstructure is present, visible in the micrograph, both after and without prior heat treatment, in comparison to the microstructure of the mounting flange. 20 , particularly in an area close to the shaft. As explained above, the term "area close to the shaft" refers to the mounting flange. 20 an area of ​​the radial or lateral extent of the mounting flange 20 , which is less than ½ of the total radial or lateral extent of the mounting flange 20 , preferably less than 1 / 3 and particularly preferably less than 1 / 4 measured from the edge of the through-opening 32 .

[0061] For better comprehension of the above statements, reference is made to the following: Fig. 5 and Fig. 6 referred. Fig. Figure 5 shows a first micrograph of an embodiment of the blind rivet nut, which was taken in the area near the shaft of the mounting flange. Fig. Figure 6 shows a second micrograph of an embodiment of the blind rivet nut, taken from an edge region of the mounting flange. Both micrographs were prepared using a steel blind rivet nut, with the material polished to a thickness of 1 µm at the measuring points.

[0062] Referring to the following discussion Fig. 7 was the first micrograph according to Fig. 5 at measuring point 5 out of Fig. 7 recorded. The second micrograph according to Fig. 6 was measured at measuring point 2 out of Fig. 7 was recorded. Therefore, the upper right corner of the recording is from Fig. 6 the course of the knurling is recognizable. As can be seen from the comparison of the micrographs according to the Fig. 5 and Fig. 6 results in the microstructure in the edge region according to Fig. 6 compared to the microstructure in the shaft-adjacent area according to Fig. 5 compacted.

[0063] The area of ​​the blind rivet nut in Fig. Section 6, which is located immediately adjacent to the knurling, is particularly densely compacted. This is based on... Fig. 6. It is also clearly visible that the compaction effect decreases the further one moves away from the edge area, i.e., towards the lower left corner of the image. Fig. 6 moves.

[0064] To verify cold forming without subsequent heat treatment, the Vickers hardness test according to DIN EN ISO 6507 can alternatively be performed, the content of which is fully incorporated herein by reference, particularly with regard to the test according to HV 0.3. For better comprehensibility, the following is provided in this context, especially concerning the possible measuring points and ranges for an initial Vickers hardness test. H1 and a second Vickers hardness H2 , on Fig. 7 referred.

[0065] To demonstrate the differences, the first Vickers hardness test is used. H1 immediately adjacent to the knurling 22 on the side of the mounting flange facing away from the shaft 20 measured. Immediately adjacent to the knurling. 22 This means that a first measuring point 30 for the first Vickers hardness H1 on one of the valleys of the knurling 22 connecting line 28arranged or offset radially or laterally further outwards in the direction of the knurling tips 22 is arranged. Referring to Fig. The 7 points show 1 until 3 corresponding first measuring points 30 As also in Fig. 7. It is evident that the valleys of the knurling are 22 connecting line 28 to form a line that defines the deepest valleys of the knurling 22 connects them. Therefore, and especially when the knurling 22 a sequence of deep and shallow valleys, for example alternating deep and shallow valleys, the line connecting the valleys 28 formed in such a way that the adjacent deep valleys are connected. In other words, this means that the shallower valleys are omitted during the formation of the line.

[0066] The second Vickers hardness H2is located in an area adjacent to a passageway 32 the blind rivet nut 1 on the side of the mounting flange facing away from the shaft 20 measured. Here, "adjacent to the opening" means adjacent to the passage. 32 that a second measuring point 34 for the second Vickers hardness H2 in an area of ​​the radial or lateral extent of the mounting flange 20 is arranged, which is smaller than ½ of the total radial or lateral extent of the mounting flange 20 , preferably less than 1 / 3 and particularly preferably less than 1 / 4. Referring to Fig. The 7 points show 4 until 6 corresponding second measuring points. In Fig. 6 the dashed line runs at half the total radial extent of the mounting flange. 20 .

[0067] The test is carried out using the Vickers hardness test and the test conditions according to HV 0.3, wherein the first Vickers hardness H1 determined in this way is at least 1.2 times the second Vickers hardness H2, preferably at least 1.4 times and particularly preferably at least 1.55 times.

[0068] The first Vickers hardness H1 and second Vickers hardness H2 determined according to HV 0.3, as well as the resulting ratio, depend on the material used for the blind rivet nut. 1was used. When using aluminum, the following two examples result. In the first example, the mean value of several measurements for the first Vickers hardness is approximately 93.5, and the mean value of several measurements for the second Vickers hardness is approximately 77.7. It follows that the first Vickers hardness is 1.2 times the second Vickers hardness. In the second example, the mean value of several measurements for the first Vickers hardness is approximately 76, and the mean value of several measurements for the second Vickers hardness is approximately 58. The first Vickers hardness is therefore 1.3 times the second Vickers hardness. Based on the values ​​for the first Vickers hardness H1 and the second Vickers hardness H2, it can be seen that both the first Vickers hardness H1 and the second Vickers hardness H2 are below 100 but above 50.

[0069] For steel and stainless steel as materials for the blind rivet nut, the following four examples apply. In the first example, the mean value from several measurements for the first Vickers hardness is approximately 168, and the mean value from several measurements for the second Vickers hardness is approximately 115. Therefore, the first Vickers hardness is 1.46 times the second Vickers hardness. According to the second example, the mean value from several measurements for the first Vickers hardness is 188, and the mean value from several measurements for the second Vickers hardness is 131. Thus, the first Vickers hardness is 1.44 times the second Vickers hardness. In the third example, the mean value from several measurements for the first Vickers hardness is 187, and the mean value from several measurements for the second Vickers hardness is 115. Therefore, the first Vickers hardness is 1.63 times the second Vickers hardness.Finally, according to a fourth example, the mean value from several measurements for the first Vickers hardness is 309, and the mean value from several measurements for the second Vickers hardness is 191. Thus, the first Vickers hardness, H1, is 1.62 times the second Vickers hardness, H2. Specifically, for steel and stainless steel as materials for the blind rivet nut, it further follows from these values ​​that the first Vickers hardness, H1, is at least 150, and the second Vickers hardness, H2, is not less than 100. Reference symbol list 1 blind rivet nut 10 shaft 12 folding zones 14 Knurling on the shaft 16 internal threads 20 Mounting flange 22 Knurling on the mounting flange 24 axial projection on the side facing the shaft 26 axial projection on the side facing away from the shaft Line 28 30 measuring points for the first Vickers hardness H1 32 Passage opening 34 measuring point for the second Vickers hardness H2 QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] EP 1279839 A2

[0002] EP 1710454 A1 [0002, 0003] DE 102011076069 A1

[0004] EP 0691480 A1

[0005] DE 69711285 T2

[0006] EP 2549592 B1

[0008] Cited non-patent literature

[0000] DIN EN ISO 6507 [0025, 0064]

Claims

[1] Blind rivet nut (1) for a screw connection between a support component and a fastening component, comprising: a. a sleeve-shaped shaft (10) with an internal thread (16) that can be inserted into a mounting hole of the support component, a mounting flange (20) at a first end and a folding zone (12) that can be folded into a compression bead and supported on opposite sides of the support component, wherein b. the mounting flange (20) has a knurling (22) on a radially outer side as well as axial projections (24) on the side of the mounting flange (20) facing the shaft and / or axial projections (26) on the side of the mounting flange (20) facing away from the shaft, which are arranged immediately adjacent to the radial outer side. [2] Blind rivet nut (1) according to claim 1, in which the knurling (22) and the axial projections (24, 26) were produced by cold forming, in particular without subsequent thermal treatment, so that a changed microstructure of the material in the area of ​​the knurling (22) and the axial projections (24, 26) is present in comparison to the rest of the blind rivet nut (1), in particular in a shaft-adjacent area of ​​the fastening flange (20). [3] Blind rivet nut according to one of the preceding claims, wherein a first Vickers hardness H1 and a second Vickers hardness H2 are: H 1 ≥ fH 2, where the first and second Vickers hardness values ​​are measured using HV 0.3, the first Vickers hardness H1 is determined on a side of the mounting flange (20) facing away from the shaft, immediately adjacent to the knurling (22), the second Vickers hardness H2 is determined on a side of the mounting flange (20) facing away from the shaft, adjacent to a through opening (32), particularly in an area near the shaft, and the factor f is at least 1.2, preferably at least 1.4 and particularly preferably at least 1.

55. [4] Blind rivet nut according to claim 3, wherein a first measuring point for determining the first Vickers hardness H1 is arranged on a line (28) connecting the valleys of the knurling (22) or is arranged radially or laterally further outwards in the direction of the tips of the knurling (22) and a second measuring point for determining the second Vickers hardness H2 is arranged in a region of the radial or lateral extent of the mounting flange (20) that is less than ½ of the total radial or lateral extent of the mounting flange (20), preferably less than 1 / 3 and particularly preferably less than 1 / 4 measured from the edge of the through-opening (32). [5] Blind rivet nut (1) according to one of the preceding claims, in which a cold forming-specific microstructure of the knurling (22) and / or the axial projections (24, 26) is recognizable via a micrograph, after or without prior thermal treatment in comparison to a microstructure of the fastening flange (20), in particular in a shank area. [6] Blind rivet nut (1) according to one of the preceding claims, the axial projections (24, 26) of which are larger than 20 µm, preferably larger than 30 µm and particularly preferably larger than 40 µm with respect to a respective surface of the fastening flange (20), in particular in a shaft-adjacent area. [7] Blind rivet nut (1) according to any of the preceding claims, made of one of the following materials: steel, stainless steel, aluminium or brass. [8] Blind rivet nut (1) according to one of the preceding claims, wherein the fastening flange (20) has a thickness of at least 0.5 mm, preferably at least 0.75 mm and particularly preferably 1.0 mm. [9] Arrangement consisting of a support component and a blind rivet nut (1) arranged therein according to one of the preceding claims. [10] Arrangement according to claim 9, further comprising a fastening component which is connected to the support component by means of the blind rivet nut (1). [11] Arrangement according to claim 9 or 10, wherein the support component and / or the fastening component is one of the following: aluminium with an oxide layer, steel with a coating, in particular with a cathodic dip coating (e-coating) or an electroplating coating, or carbon fiber reinforced plastic (CFRP). [12] Manufacturing method of a blind rivet nut (1) according to any one of claims 1-8, comprising the following steps: a1. Cold forming (A1) of a material for the blind rivet nut (1) such that the blind rivet nut (1) comprises a sleeve-shaped shank (10) with an internal thread (16) that can be inserted into a mounting hole of the support component, and has a mounting flange (20) at a first end and a folding zone (12) that can be folded into a compression bead and supported on opposite sides of the support component, or a2. Turning (A2) the material for the blind rivet nut (1) such that the blind rivet nut (1) comprises a sleeve-shaped shaft (10) with an internal thread (16) that can be inserted into a mounting hole of the support component, and has a mounting flange (20) at a first end and a folding zone (12) that can be folded into a compression bead and supported on opposite sides of the support component, thereafter b. Cold forming (B) of the blind rivet nut (1) such that the fastening flange (20) has knurling (22) and axial projections (24) on the side of the fastening flange (20) facing the shaft and / or axial projections (26) on the side of the fastening flange (20) facing away from the shaft, which are arranged immediately adjacent to the radial outside. [13] Manufacturing method according to claim 12, which further comprises the following step prior to the cold forming of the blind rivet nut (1) in step B: c. Heating (C) of the blind rivet nut (1). [14] Manufacturing method according to claim 12 or 13, wherein the knurling (22) and the axial projections (24, 26) were produced by cold forming, in particular without subsequent thermal treatment, so that a modified microstructure of the material in the area of ​​the knurling (22) and the axial projections (24, 26) is present in comparison to the rest of the blind rivet nut (1), in particular in a shaft-adjacent area of ​​the fastening flange (20). [15] Manufacturing method according to one of claims 12-14, in which, after cold forming of the blind rivet nut (1), a cold forming-specific microstructure is present in the area of ​​the knurling (22) and the axial projections (24, 26) after or without prior thermal treatment in comparison to a microstructure of the fastening flange (20), particularly in a shaft-adjacent area. [16] Manufacturing method according to one of claims 12-15, wherein the material for the blind rivet nut (1) is selected from one of the following: steel, stainless steel, aluminium or brass.

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