WO2023011991A1

WO2023011991A1 - Riveted connection

Info

Publication number: WO2023011991A1
Application number: PCT/EP2022/070968
Authority: WO
Inventors: Jochen Rintelmann; Jan-Oliver Brassel
Original assignee: Audi Planung GmbH
Priority date: 2021-08-03
Filing date: 2022-07-26
Publication date: 2023-02-09
Also published as: DE102021120193A1

Abstract

The invention relates to a riveted connection in which a rivet foot (7) of a rivet element (5) is driven with a setting force (F) into at least one single- or multi-part, in particular pilot hole-free, component (1, 3) of material thickness (s), to be precise with spreading apart of the rivet foot (7) and while maintaining a residual bottom thickness (r) in the component (1, 3), wherein the rivet foot (7) has, in the non-deformed state, a cavity (13) which is open towards the rivet foot end side (11). According to the invention, the component side facing away from the setting side is designed to have a completely planar surface, that is to say without die-induced bowing, such that in the component side facing away from the setting side there occurs no material deformation and/or material change in the region of the residual bottom thickness (r).

Description

rivet connection

The invention relates to a rivet connection according to the preamble of claim 1, a rivet element according to claim 9 and a process arrangement or a method for producing a rivet connection according to claim 10.

In such a rivet connection, the rivet foot of a rivet element is driven into a component with a setting force, specifically while maintaining a residual base thickness in the component and with the rivet foot spreading open. When driven in, the rivet foot has an expanded cross-section compared to its undeformed state.

In the prior art, the above riveted connection is produced with the aid of a setting device in which a setting piston drives the rivet element into the component. The component is supported on a die on the side opposite the setting piston. This has a profiled die surface with a recess (i.e. die engraving) by means of which the spreading behavior of the rivet foot is controlled.

In such a setting process, a material deformation or material change takes place over the entire material thickness of the component material (ie from the setting side to the die side). Especially when using a component material with limited deep-drawing capability with low ductility (e.g. die-cast aluminium), such a material deformation can occur lead to an impairment of the connection strength by the driven-in rivet element in the component material.

The object of the invention is to provide a riveted connection which, in comparison to the prior art, enables perfect connection strength even when using a component material that has only limited deep-drawing capability.

The object is solved by the features of claim 1, 9 or 10. Preferred developments of the invention are disclosed in the dependent claims.

The invention is based on a rivet connection in which the rivet foot of a rivet element is driven with a setting force into at least one component, in particular one without a pre-drilled hole, with the rivet foot spreading open and a residual base thickness being maintained in the component. In the non-deformed state, the rivet foot has a rivet foot cavity which is open toward the rivet foot end face. The rivet foot can be formed with a rivet foot wall section delimiting the cavity. In the non-deformed state, this is expanded radially outwards by a pre-expansion cone angle as far as the rivet foot end face. It has been shown that the expanding behavior of the rivet element is supported by the conically widened rivet foot wall section in such a way that a common die with a profiled die surface (ie die engraving) can be dispensed with in the setting process. The spreading behavior of the rivet foot is independent of the component thickness and is essentially controlled by the rivet foot geometry, but not by a profiled die surface, as is the case in the prior art.

In contrast to the prior art, according to the invention, the material deformation or material change is based on the penetration depth of the The rivet element is limited to the component material, so that there is no material deformation or material change on the die side in the area of the remaining base thickness.

Overall, a rivet connection is thus provided in which there is a significantly reduced material deformation during the setting process compared to the prior art. The invention can therefore preferably be used for component materials that can only be deep-drawn to a limited extent, such as die-cast aluminum, in which, due to the reduced material deformation in the component material, perfect connection strength can be achieved using the rivet element in the component material despite low ductility.

In a technical implementation, the conically widened rivet foot wall section can transition along the longitudinal axis of the rivet element in the direction of the rivet head at a transition edge or a kink point into a fully cylindrical or hollow cylindrical rivet foot section. The rivet head follows the solid or hollow cylindrical rivet foot section. In this case, the spreading behavior in the setting process is only controlled by measuring the pre-spreading cone angle and the axial length distribution between the conically widened rivet foot wall section and the cylindrical rivet foot wall section, but not by a profiled die surface.

In the non-deformed state, the rivet element is preferably designed to be rotationally symmetrical about a longitudinal axis of the rivet element. In addition, the rivet head can have an arbitrarily designed functional section on its upper side, such as a threaded bolt, a locking element or the like.

In the undeformed state of the rivet element, the outer diameter of the conically widened rivet foot wall section increases up to Cone-like rivet foot end face. In contrast to this, the outer diameter of the cylindrical rivet foot section remains constant along the longitudinal axis of the rivet element (ie between the rivet head and the kink point).

In one embodiment variant, the cylindrical rivet foot section cannot be made of solid material, but rather have a hollow-cylindrical rivet foot wall section that delimits the cavity. During the rivet element manufacturing process, the hollow-cylindrical rivet foot wall section can act as a guide section in which an expanding mandrel, described later, is guided centrally.

The wall thickness of the cylindrical rivet foot wall section and the wall thickness of the conically widened rivet foot wall section can be dimensioned to be essentially the same.

The rivet foot cavity can protrude from the rivet foot end face along the longitudinal axis of the rivet element in the axial direction by a profile depth up to an inner apex point in the rivet foot. In a first embodiment variant, the cavity can extend in the axial direction with an axial oversize beyond the kink point in the direction of the rivet head. As an alternative to this, in a second embodiment variant, the apex of the cavity and the buckling point can be positioned at approximately the same axial height.

In a technical implementation, the conically widened rivet foot wall section can terminate at the rivet foot end face with an annular, for example acute-angled cutting edge. The rivet foot according to the invention can be realized with a cutting edge of any cutting geometry.

As already mentioned, according to the invention the spreading of the rivet foot in the setting process is solely due to the pre-spreading cone angle and the Height position of the kink controllable. In this way, a die with a profiled die surface can be dispensed with in the setting process. Instead of this, the setting piston can interact with a completely planar counter-contour of the tool (ie anvil) in the setting process. In this case, the side of the component facing away from the setting side is designed to be completely flat, that is to say without any arching on the die side.

The rivet element according to the invention can be manufactured in a process sequence described below in the cold forging process. A rivet element base material can thus be provided in a first process step. Depending on the application, the base material can be, for example, a weldable wire material, in particular a cold extruded steel or a cold upsetting steel. With the help of a cold forging tool, the base material is processed into a rivet element blank. In the rivet element blank, the rivet foot is cylindrical with a constant outer diameter over its entire length. The rivet foot cavity of the rivet element blank is not dome-shaped but completely hollow-cylindrical, namely over its entire axial length from the rivet foot end face to the inner head-side inner apex.

In a second process step, the rivet foot is conically widened, in which the conically widened rivet foot wall section is produced on the rivet foot end face by plastic deformation. For this purpose, an expanding mandrel with a pre-expansion cone can preferably be driven into the cavity of the rivet element blank, as a result of which the conically widened rivet foot wall section is produced.

A correctly positioned centering of the expanding mandrel in relation to the rivet element is of great importance for a perfect function of the rivet element. Against this background, it is preferred if the Vorspreizkonus the expanding mandrel at the Mandrel tip merges into a cylindrical centering pin. In the second process step, the cylindrical centering pin of the expanding mandrel is inserted into the hollow cylindrical rivet element cavity with a small hole clearance, as a result of which the expanding mandrel and the rivet element are aligned centrally to one another.

In a further embodiment, the following active principle can be used to secure the rivet element on the component: The rivet foot geometry according to the invention thus forms a bistable spring section which has two states of equilibrium. A first state of equilibrium corresponds to the cross-sectionally reduced, non-deformed rivet foot state. The effect of the setting force causes the rivet foot to switch to the second state of equilibrium, in which the rivet foot is braced in the component with an expanded cross section. The transition to the expanded state occurs essentially without building up a springback force that prestresses the rivet element in the direction of the non-deformed state.

According to the invention, the rivet element is deformed in the setting process using the so-called spring buckling effect (also known as the click frog effect). The spring buckling effect is a physical effect in which the shape of the rivet element has two stable states that can be converted into one another by applying a suitable force.

In a technical implementation, the component in the non-deformed state cannot be formed completely without pre-holes, but rather have a pre-hole at the joint to be produced. In the assembled state, the rivet foot of the rivet element is braced against the inner circumference of the pilot hole. In the spread state, the rivet foot wall can be folded over in the opposite direction to the setting direction, ie in the direction of the rivet head. In this case, the positioning edge can be in spreading engagement with the inner circumference of the pilot hole for the component.

In a technical implementation, the component can be a cast part, for example an aluminum die-cast part, while the rivet element can be made from a cold-forming material. Especially in this case, it is preferred if the component is stressed during the setting process essentially without plastic deformation, that is to say in particular only elastically. The component can particularly preferably remain largely undeformed after the setting process has taken place.

With regard to a perfect transition of the rivet element from the undeformed state to the expanded state, it is advantageous if the component pre-hole has a corresponding activation contour. By means of the activation contour, a transfer of the rivet element from the non-deformed state to the second expanded state can be designed in a process-reliable manner during the setting process. In a preferred embodiment variant, the component pilot hole can have the following geometry: The component pilot hole can be implemented as a blind hole with a closed bottom. The blind hole can have a large-diameter insertion section. At a circumferential ring shoulder, this merges into a small-diameter countersink. The contact edge of the still undeformed rivet element can lie on a diameter that is larger than the inner diameter of the ring shoulder. This allows (in preparation for the setting process) the rivet element to be positioned with its contact edge on the ring shoulder of the component pilot hole.

When the setting force acts, the rivet element can expand with its contact edge radially outwards, specifically until a maximum is reached outside diameter. In the further course of the setting process, the rivet element can be driven into the pre-drill countersink by an additional over-centre stroke. This results in over-shaping or over-spreading of the rivet foot, during which the rivet foot changes to the spread state.

The rivet element can preferably be made of a cold impact material, in which a deformation limit is exceeded, particularly during overspreading, at which the rivet element material hardens, which is advantageous with regard to increased connection strength between the rivet element and the component. Therefore, according to the invention, there is no need for a die whose die shape supports the spreading of the rivet foot. Instead, the component can be clamped between a hold-down device and a planar anvil.

The setting process according to the invention can be part of a fully automatic process chain in which a setting device is attached to the distal end of a robot arm of an industrial robot that works autonomously by means of a program control. In order to ensure a perfect setting process, it is preferred if the outside diameter of the rivet foot is dimensioned smaller than the outside diameter of the annular shoulder. In this way, the still undeformed rivet element can be positioned with its contact edge in a floating bearing, ie with transverse play, on the annular shoulder, as a result of which component and/or manufacturing tolerances can be compensated for.

When using a die-cast part, the component pilot hole can be created in the component surface during the casting process. In this case, the component pilot hole can have a cone-like inner circumference, which serves as a draft angle. During the setting process, the cone-like inner circumference also acts as a lead-in bevel to ensure a flawless To ensure positioning of the rivet element on the annular shoulder of the component pilot hole.

An exemplary embodiment of the invention is described below with reference to the accompanying figures.

Show it:

FIG. 1 shows a riveted connection in a sectional view;

FIG. 2 shows a rivet element in a non-deformed state in a side sectional view;

Fig. 3 is a view showing a setting process;

FIGS. 4 to 6 are views showing a process sequence for manufacturing the rivet element;

FIGS. 7 and 8 views of further exemplary embodiments; as well as

Figure 9 to 11 another embodiment.

FIG. 1 shows a finished riveted connection, in which a first component 1 and a second component 3 are connected to one another with the aid of a rivet element 5 . In FIG. 1, the two components 1, 3 have a sheet metal thickness s. As an alternative to this, a riveted connection is also possible in just a one-piece component with the same sheet thickness s. In the riveted joint, a rivet foot 7 of the rivet element 5 is driven into the two pre-hole-free components 1, 3 with a setting force F (Figure 3), specifically with the rivet foot 7 spreading open and a residual base thickness r being maintained in the lower component 3. The Rivet element 5 also has a rivet head 9 which rests with its underside on the surface of first component 1 .

The geometry of the rivet element 5 in the non-deformed state is described below with reference to FIG. The rivet foot 7 has a cavity 13 which is open towards the rivet foot end face 11 and protrudes into the rivet foot 7 in the axial direction by a profile depth t up to an apex 15 . An annular cutting edge 16 is formed on the rivet foot end face 11 .

A core of the invention is that the rivet foot 7 is designed in two parts along the longitudinal axis L of the rivet element, namely with a hollow-cylindrical rivet foot section 17 molded onto the rivet head 9. This goes at a transition edge 19 or kink point into a rivet foot delimiting the cavity 13 -Wall section 21 above. The rivet foot wall section 21 is widened radially outwards in FIG. By measuring the pre-expansion cone angle a and the length distribution between the two rivet foot sections 17, 21, the expansion behavior of the rivet element in the setting process (FIG. 3) is controlled according to the invention.

In FIG. 2, the outer diameter di of the conically widened rivet foot wall section 21 increases continuously from the kink point 19 to the rivet foot end face 11 . The outer diameter d2 of the cylindrical rivet foot section 17, on the other hand, remains constant along the longitudinal axis L of the rivet element. As can also be seen from FIG. 2, the wall thicknesses w of the cylindrical rivet foot wall section 23 and the conically widened rivet foot wall section 21 are essentially the same size. The cavity 13 extends in the figure 2 in the axial direction an axial oversize a (Figure 3) over the kink 19 away. In this way, the inner apex 15 (FIG. 2) and the kink 19 are offset from one another in the axial direction.

A process sequence for producing the riveted connection is illustrated below with reference to FIG. 3: Accordingly, in preparation for the setting process, the two components 1, 3 are positioned one on top of the other on a planar counter-contour 25 of the setting tool and pressed together with a holding-down device by means of a holding-down system (not shown). The rivet element is then driven into the two components 1 , 3 with the aid of a stamp 30 with the setting force F. During the setting process, the rivet element 5 pierces the material of the component 1 on the stamp side and is driven through this into the second component 3, while maintaining the remaining bottom thickness r in the component 3. According to FIG. Cone angle a of the conically widened rivet foot wall section 21 and controlled by the axial length distribution between the two rivet foot sections 17, 21.

Because of the planar counter-counter 25, the riveted connection does not exhibit any arching caused by the die on the side of the component facing away from the setting side. Rather, the rivet connection is completely flat on the component side facing away from the setting side. In addition, no material deformation and/or material change has taken place in the lower component 3 in the area of the remaining bottom thickness r. The material deformation or material change is therefore limited to the penetration depth of the rivet element 5 into the components 1 , 3 .

By spreading the conically widened rivet foot wall section 21 is an undercut between the rivet foot end face 11 and the Rivet head 9 generated, in which the two components 1, 3 are braced against each other.

A process sequence for the production of the rivet element 5 according to the invention is described by way of example with reference to FIGS. Roughly simplified, this has two process steps: In a first process step (Figure 4), a rivet element base material 26, i.e. a wire material, is preformed with the aid of an indicated cold forging tool 28, with the formation of a rivet element blank 27 (Figure 5). The rivet element blank 27 has a rivet foot 7 which is cylindrical with a constant outer diameter over its entire rivet foot length.

According to the invention, the cold impact tool 28 has a cylindrical stamp 30 which is driven into the rivet element base material 26 and produces the hollow cylindrical rivet foot cavity 13 . The production of the hollow-cylindrical rivet foot cavity 13 can advantageously be carried out in a single-stage cold forging process, since the friction between the stamp 30 and the base material 26 of the rivet element is reduced due to the cylindrical stamp geometry. In contrast to this, in the prior art the rivet foot cavity 13 is not hollow-cylindrical in common practice, but is designed in the shape of a spherical cap or bell. A corresponding bell-shaped punch geometry is required for this. With such a bell-shaped punch geometry, the friction between the punch and the base material of the rivet element is significantly increased in the cold forging process. The cold forging process must therefore be carried out in several stages, which is complex in terms of production technology.

The provided in the figure 5 rivet element blank 27 can depending on

Requirement profile in the following second process step (Figure 6) be further processed. In the second process step (FIG. 6), the rivet foot 7 is widened conically. In this way, the conically widened rivet foot wall section 21 is produced.

Depending on the material properties and/or component thickness of the component(s) 1, 3, a spreading mandrel 29 with a suitable length division between the rivet foot sections 17, 21 and/or a suitable size of the pre-spreading cone angle a can be selected.

To center the expanding mandrel 29 relative to the rivet element 5, the pre-expansion cone 31 of the expanding mandrel 29 merges into a cylindrical centering pin 33 at the mandrel tip, which can be moved into the cavity 13 of the rivet element 5 with a small hole clearance.

In the first embodiment of Figures 1 to 6, the top of the rivet head 9 is flat. Instead of this, any functional section 35, for example in the form of a bolt, can also be formed on the upper side of the rivet head. The bolt-shaped functional section 35 can be formed, for example, in a rolling process with, for example, a metric thread (see FIG. 7) or with a raw thread. As an alternative to this, the functional section 35 can also be realized as a latching element (FIG. 8), so that the rivet element 5 can be produced easily with high manufacturing variability using tools.

A further exemplary embodiment is shown in FIGS. 9 to 11, in which the rivet element 5 is driven into a preliminary hole 37 in the component, which extends conically to a preliminary hole depth and terminates there with a preliminary hole bottom 39 . In the illustrated embodiment, the rivet foot 7 acts as a bistable spring section. This has two states of equilibrium, namely the non-deformed state with reduced cross-section (FIG. 9) and an expanded state (FIG. 11). Due to the action of the setting force F, the rivet element 5 changes from the undeformed state (FIG. 9) to the expanded state in which the rivet foot 7 with the expanded cross section is expanded in the component 3 . The expanded state (FIG. 11) is characterized in that (in contrast to the prior art) essentially no spring-back force is built up that prestresses the rivet element 5 in the direction of the non-deformed state. Therefore, according to the invention, a form-fitting enclosing of the rivet foot tip by means of the component material can be dispensed with.

The pre-hole geometry of component 3, the rivet element geometry and the setting process according to the invention are described below with reference to FIGS. 9 to 11: According to FIG.

Folding over of the rivet foot wall 7 acting as a bistable spring section is supported by a special activation contour in the component pilot hole 37, which is designed as follows: The component pilot hole 37 in FIG. 9 has an insertion section 43 of large diameter. In the direction of the bottom 39 of the pre-hole, this gradually changes at a circumferential annular shoulder 45 into a pre-hole countersink 47 of small diameter. When the rivet element 5 is still undeformed, its contact edge has a diameter dK (FIG. 9) that is larger than the inside diameter di of the annular shoulder 45. In addition, the outside diameter dK of the contact edge is smaller than the outside diameter dA of the annular shoulder.

The setting process is carried out with a setting device which, in FIG. 9, has the hold-down device 49 in which a setting piston 30 is guided in a stroke-adjustable manner. The component 3 is clamped between the hold-down device 49 and a planar counter-contour 25 . In contrast to a die known from the prior art, the counter-contour 25 does not have any special contour to support a spreading movement of the rivet foot 7, but is rather designed with a planar surface as an anvil. Also, there is no deformation of the component 3. In FIG. When the setting force F acts, the rivet foot 7 widens radially outward with its contact edge, specifically until a setting stroke dead center T is reached (FIG. 10). In the setting stroke dead center T, the contact edge of the rivet element 5 is expanded with a maximum diameter dmax and is in expanding engagement with the inner circumference of the large-diameter insertion section 43 of the component pilot hole 37. In addition, the end face of the rivet foot tip is in large-area contact with the annular shoulder 45. It is also located in the setting stroke dead center T (FIG. 10), the spread angle β spanned by the spread lines is approximately 180°.

According to the invention, the setting stroke is extended beyond the dead center T with an over-dead center stroke h (FIG. 10). In the further course of the setting process, therefore, the rivet foot 7 is driven in by the over-center stroke h in the direction of the pre-hole countersink 47 . This results in an overshaping or overspreading of the rivet foot wall, in which the rivet foot wall changes into the expanded state (FIG. 11). In the spread state, the spread angle β spanned by the spreading lines 51 (compared to the setting stroke dead center T according to FIG. 10) is increased to approximately 200°. The rivet foot wall is therefore turned over in the opposite direction to the setting direction, ie in the direction of the rivet head 9 . The turned-over rivet foot wall extends continuously in the circumferential direction and in the shape of a plate around the remaining rivet foot of the rivet element 5. As can also be seen in FIG. 10, the inner circumference of the large-diameter insertion section 43 of the component pilot hole 37 is cone-shaped, so that the inner circumference acts as an insertion bevel, by means of which the rivet element 5 can be easily inserted into the component pilot hole 37. In addition, the rivet element 5 is positioned on the annular shoulder 45 in a floating bearing (FIG. 10), that is to say positioned with lateral play, as a result of which component and/or manufacturing tolerances can be compensated for.

Reference character list

1, 3 components

5 rivet element

7 rivet foot

9 rivet head

11 Rivet foot face

13 cavity

15 vertex

16 cutting edge

17 cylindrical rivet foot section

19 kink or transition edge

21 conical rivet foot wall section

23 cylindrical rivet foot wall section

25 planar counter-contour

26 rivet element base material

27 rivet element blank

28 cold striking tool

29 expanding mandrel

30 setting pistons, stamps

31 pre-expansion cone

33 centering pin

35 functional section

37 component pilot hole

39 prehole floor

43 insertion section 45 circumferential ring shoulder

47 diameter small pre-drill countersink

49 hold-down device

51 spread line

T dead center dmax diameter

L Longitudinal axis of the rivet element a Pre-spreading cone angle ß Spreading angle h Over dead center stroke t Profile depth w Wall thicknesses a Axial overhang di, d ₂ outer diameter s Sheet thickness dK Contact edge diameter dA Ring shoulder outer diameter di Ring shoulder inner diameter

Claims

patent claims

1 . Riveted joint, in which a rivet foot (7) of a rivet element (5) is driven with a setting force (F) into at least one-part or multi-part component (1, 3), in particular without a pre-drilled hole, of a material thickness (s), specifically with the rivet foot spreading open ( 7) and while maintaining a residual bottom thickness (r) in the component (1, 3), the rivet foot (7) in the undeformed state having a cavity (13) open to the rivet foot end face (1 1), characterized in that the The component side facing away from the setting side is completely flat, i.e. without any arching caused by the die, and/or that no material deformation and/or material change occurs in the component side facing away from the setting side in the area of the remaining base thickness (r).

2. Riveted connection according to claim 1, characterized in that the rivet foot (7) is formed with a rivet foot wall section (21) delimiting the cavity (13) which, in the non-deformed state, extends by a pre-spreading Cone angle (a) is expanded radially outwards to support and control the spreading behavior of the rivet element (5) in the setting process.

3. Riveted connection according to claim 2, characterized in that the conically widened rivet foot wall section (21) along the longitudinal axis (L) of the rivet element in the direction of the rivet head (9) at a transition edge or kink (19) into a fully cylindrical or hollow-cylindrical rivet foot section (17) which is followed by the rivet head (9). Rivet connection according to one of the preceding claims, characterized in that the outside diameter (di) of the conically widened rivet foot wall section (21) increases conically up to the rivet foot end face (11), and/or that the outside diameter (d2) of the cylindrical rivet foot section ( 17) remains constant along the longitudinal axis (L) of the rivet element. Riveted connection according to Claim 3 or 4, characterized in that the cylindrical rivet foot section (17) has a cylindrical rivet foot wall section (23) delimiting the cavity (13), and in that in particular the wall thickness (w) of the cylindrical rivet foot wall section (23) and the wall thickness (w) of the conically widened rivet foot wall section (21) are dimensioned to be essentially the same size. Rivet connection according to one of the preceding claims, characterized in that the rivet foot cavity (13), starting from the rivet foot end face (11) along the longitudinal axis (L) of the rivet element, extends in the axial direction by a profile depth (t) up to an inner apex (15 ) protrudes into the rivet foot (7), and that in particular the rivet foot cavity (13) extends in the axial direction with an axial oversize (a) beyond the kink point (19), specifically forming a hollow-cylindrical rivet foot section (17), and that particularly in the manufacturing process of the hollow-cylindrical rivet foot section (17) interacts as a centering guide with a centering pin (33) of an expanding mandrel (29). Riveted connection according to one of the preceding claims, characterized in that the spreading behavior of the rivet foot (7) in the setting process can be controlled solely by the size of the pre-spreading cone angle (a) and by the length distribution of the two rivet foot sections (17, 21), and that in particular in Setting process on a matrix with a profiled matrix surface, which supports the spreading, is to be dispensed with. Rivet element in particular for a rivet connection according to one of the preceding claims, wherein the rivet element is preferably manufacturable in a cold impact process in which

- In a first process step, a rivet element base material (26) can be processed using a cold forging tool (28), specifically with the formation of a rivet element blank (27), the rivet foot (7) being cylindrical with a constant outer diameter over its entire rivet foot length and/or a hollow cylindrical rivet foot cavity (13) can be provided, and

- In a second process step, the rivet foot (7) is widened conically, in which the conically widened rivet foot wall section (21) can be produced on the rivet foot end face (11) by plastic deformation. Rivet element according to Claim 8, characterized in that in the second process step a mandrel (29) with a pre-spreading cone (31) can be driven into the rivet foot cavity (13) of the rivet element blank (27), specifically with the formation of the conically widened rivet foot Wall section (21), and that in particular for centering the expanding mandrel (29) relative to the rivet element (5) of the pre-spreading cone (31) of the expanding mandrel (29) at the mandrel tip in a cylindrical 22 centering pin (33), which can be moved into the cavity (13) of the rivet element (5) with a small hole play. Process arrangement or method for producing a rivet connection according to one of Claims 1 to 8.