Self-punching functional element, component assembly, and method of manufacturing a component assembly

Abstract

A self-punching functional element serves for the fastening to a workpiece and comprises a head part that has an abutment surface for introducing a punching force directed in a punching direction into the functional element and a rivet section that extends away from the head part in the punching direction and that comprises a free end that is provided with a first punching edge for punching a slug out of the workpiece. The functional element further comprises a functional section that has a punching pilot that is radially surrounded by the rivet section, that extends away from the head part in the punching direction, and that has a second punching edge for punching a hole into the slug. The second punching edge is set back with respect to the first punching edge in the punching direction.

Claims

1. A self-punching functional element for fastening to a workpiece, said self-punching functional element comprising a head part that has an abutment surface for introducing a punching force directed in a punching direction into the functional element and a rivet section that extends away from the head part in the punching direction and that comprises a free end that is provided with a first punching edge for punching a slug out of the workpiece; and a functional section that has a punching pilot that is radially surrounded by the rivet section, that extends away from the head part in the punching direction, and that has a second punching edge for punching a hole into the slug, wherein the second punching edge is set back with respect to the first punching edge in the punching direction.

2. The functional element in accordance with claim 1, wherein the workpiece is a sheet metal part.

3. The functional element in accordance with claim 1, wherein for receiving a slug ring is formed between the rivet section and the punching pilot.

4. The functional element in accordance with claim 3, wherein a gap is an annular gap.

5. The functional element in accordance with claim 3, wherein the gap is bounded by a radial outer surface of the punching pilot and by a radial inner surface of the rivet section.

6. The functional element in accordance with claim 1, wherein at least one of the rivet section and the punching pilot is annular.

7. The functional element in accordance with claim 1, wherein at least one of the rivet section and the punching pilot is one of circular, oval, and polygonal.

8. The functional element in accordance with claim 1, wherein the head part is flange-like and has a workpiece contact section, with the rivet section and the punching pilot extending away from said workpiece contact section.

9. The functional element in accordance with claim 8, wherein the workpiece contact section comprises a first contact surface and a second contact surface that are in particular annular, with the first contact surface being arranged between the punching pilot and the rivet section and the second contact surface being arranged radially outside the rivet section.

10. The functional element in accordance with claim 9, wherein the first contact surface is set back with respect to the second contact surface in the punching direction.

11. The functional element in accordance with claim 1, wherein the ratio of an extent of the rivet section in the punching direction to an extent of the punching pilot in the punching direction amounts to approximately two to approximately six.

12. The functional element in accordance with claim 1, wherein the rivet section and the punching pilot extend in parallel with one another.

13. The functional element in accordance with claim 1, wherein the punching pilot has an undercut.

14. The functional element in accordance with claim 1, wherein the free end of the rivet section is radially outwardly rounded or inclined at least in sections.

15. The functional element in accordance with claim 1, further comprising at least one feature providing security against rotation at the rivet section and/or at the workpiece contact section.

16. The functional element in accordance with claim 1, wherein the functional section is provided with a thread.

17. The functional element in accordance with claim 1, wherein the functional element is configured as a self-punching nut element.

18. A component assembly that has a workpiece having a punched hole and a functional element, said self-punching functional element comprising a head part that has an abutment surface for introducing a punching force directed in a punching direction into the functional element and a rivet section that extends away from the head part in the punching direction and that comprises a free end that is provided with a first punching edge for punching a slug out of the workpiece; and a functional section that has a punching pilot that is radially surrounded by the rivet section, that extends away from the head part in the punching direction, and that has a second punching edge for punching a hole into the slug, wherein the second punching edge is set back with respect to the first punching edge in the punching direction, said functional element being inserted into the punched hole while separating a punched slug by means of the first punching edge such that reshaped material of the rivet section at least sectionally engages behind material of the workpiece adjoining the punched hole.

19. The component assembly in accordance with claim 18, wherein a slug ring separated from the punched slug by means of the punching pilot is received in a radial direction between the rivet section and the punching pilot.

20. The component assembly in accordance with claim 18, wherein the reshaped material forms an undercut closed in a peripheral direction.

21. The component assembly in accordance with claim 20, wherein the material of the rivet section is radially outwardly reshaped to form the undercut.

22. The component assembly in accordance with claim 18, wherein a punched margin produced by the first punching edge is flanged by the reshaping of the rivet section.

23. The component assembly in accordance with claim 18, wherein an assembly region of the workpiece surrounding the punched hole is reshaped while forming a recess, with the reshaped rivet section and the punching pilot being completely received in the recess in the punching direction.

24. A method of manufacturing a component assembly that has a workpiece having a punched hole and a functional element, said self-punching functional element comprising a head part that has an abutment surface for introducing a punching force directed in a punching direction into the functional element and a rivet section that extends away from the head part in the punching direction and that comprises a free end that is provided with a first punching edge for punching a slug out of the workpiece; and a functional section that has a punching pilot that is radially surrounded by the rivet section, that extends away from the head part in the punching direction, and that has a second punching edge for punching a hole into the slug, wherein the second punching edge is set back with respect to the first punching edge in the punching direction, said method comprising the steps: providing the functional element; providing the workpiece; introducing a punching force into the functional element to produce the punched hole in the workpiece while separating a punched slug by means of the first punching edge of the rivet section and to separate a slug ring from the punched slug by means of the second punching edge of the punching pilot; and reshaping material of the rivet section to at least sectionally engage behind material of the workpiece adjoining the punched hole.

25. The method in accordance with claim 24, wherein the material of the rivet section is outwardly reshaped to form an undercut closed in the peripheral direction.

26. The method in accordance with claim 24, wherein the reshaping of the material of the rivet section takes place by means of a die, with the material of the rivet section being outwardly reshaped by pressing the free end against a reshaping geometry of the die extending transversely to the punching direction.

27. The method in accordance with claim 26, wherein an assembly region of the workpiece surrounding the punched hole is reshaped by means of an elevated portion of the die surrounding the reshaping geometry and directed opposite to the punching direction.

28. The method in accordance with claim 26, wherein the separation of the slug ring takes place by means of an edge of the die cooperating with the punching pilot.

Description

[0040] FIG. 1 shows a perspective view of a functional element in accordance with an embodiment;

[0041] FIG. 2 shows a further perspective view of the functional element of FIG. 1;

[0042] FIG. 3 shows the functional element of FIG. 1 shown in half-section;

[0043] FIG. 4 shows the functional element of FIG. 1, a workpiece, and a die, each shown in half-section;

[0044] FIG. 5 shows a component assembly in accordance with an embodiment; and

[0045] FIG. 6 shows an enlarged view of the detail D of FIG. 5.

[0046] FIGS. 1 and 2 show a functional element 10 in different perspective views that is configured as a self-punching rivet nut for punching in a punching direction S. In the present example, the punching direction S extends in parallel with the direction of extent of the axis of symmetry A of the functional element 10.

[0047] The functional element 10 comprises a head part 11, which is formed in a flange-like manner and which is provided with a workpiece contact section 33, and a functional section 13. The head part 11 is provided with an abutment surface 15, which extends perpendicular to the punching direction S, and an annular rivet section 17 that extends away from the workpiece contact section 33 in the punching direction S. The functional section 13 comprises a bore 45, which extends coaxially to the axis of symmetry A and which is provided with an internal thread 41 (see FIG. 3), and an annular punching pilot 25 that extends coaxially to the rivet section 17 in the punching direction S away from the workpiece contact section 33 and that is radially surrounded by the rivet section 17.

[0048] The rivet section 17 has a radially outwardly rounded free end 19 that is radially inwardly provided with a first punching edge 21. However, the punching pilot 25 is equipped with a second punching edge 23 that is set back with respect to the first punching edge 21 in the punching direction S.

[0049] The workpiece contact section 33 comprises an annular first contact surface 35 visible in FIG. 3 and an annular second contact surface 37. The first contact surface 35 is set back with respect to the second contact surface 37 in the punching direction S and connects a radial outer surface 29 of the punching pilot 25 to a radial inner surface 31 of the rivet section 17 such that an annular gap 27 arranged between the rivet section 17 and the punching pilot 25 is axially bounded by the first contact surface 35 and radially bounded by the radial outer surface 29 and the radial inner surface 31.

[0050] An outer wall of the punching pilot 25, and thus the outer surface 29, extends slightly conically and diverging in the punching direction at an angle of inclination relative to the punching direction S that amounts to approximately 5° in the present example and that can generally be in the range of up to 20°, preferably up to 10°, in particular 5° or less.

[0051] The ratio of an extent of the rivet section 17 in the punching direction S, measured from the first contact surface 35 up to the first punching edge 21, to an extent of the punching pilot 25 in the punching direction S, measured from the first contact surface 35 up to the second punching edge 23, amounts to approximately four in the present example. However, the ratio can be in a range from approximately two to approximately six, preferably approximately three to approximately five.

[0052] As in particular FIGS. 2 and 3 clearly show, the workpiece contact section 33 is provided with a plurality of features providing security against rotation 39 in the form of ribs arranged at equal spacings from one another. However, alternatively or additionally to the ribs, grooves or differently shaped elements would also be conceivable as features providing security against rotation 39. In addition, the features providing security against rotation 39 could generally also be attached to a radial outer surface of the rivet section 17.

[0053] With reference to FIGS. 4 and 5, a method of manufacturing a component assembly 100 comprising the functional element 10 will be described in the following.

[0054] First, as shown in FIG. 4, a workpiece 70, here a sheet metal part, having a first surface 71 and a second surface 73 is provided next to the functional element 10. In addition, a die 90 is used in the present example that has a reshaping geometry 91 that has a reshaping surface 93 curved in cross-section.

[0055] The functional element 10, the workpiece 70, and the die 90 are then aligned with respect to one another and a punching force acting in the punching direction S is introduced into the functional element 10 via the abutment surface 15. The functional element 10, more specifically the first punching edge 21 of the rivet section 17, then impacts the first surface 71 in an assembly region 79 of the workpiece 70 so that a punched slug is separated from the workpiece 70 there in cooperation with an edge 96 of the die 90 and a punched hole bounded by a punching edge 77 is thereby produced.

[0056] In the further course of the punching process, the slug, which is now disposed on an annular surface 98 bounded by the edges 96, 97, is pushed deeper into the hollow space bounded by the rivet section 17 until the second punching edge 23, which is set back with respect to the first punching edge 21 in the punching direction S, contacts the punched slug such that a centrally arranged hole is punched into the punched slug by means of the second punching edge 23 and an edge 97 of the die 90 provided for this purpose. In other words, a slug ring 75 is separated from the punched slug by means of the second punching edge 23 and is fixed in the gap 27, as shown in FIGS. 5 and 6. The slug separated from the slug is reliably disposed of downwardly—i.e. in the punching direction—through a passage 99 of the die 90 such that the functional section 13 is freely accessible. This so-to-say happens automatically in the course of the punching process. Additional worksteps are not required.

[0057] Due to the punching force, the free end 19 of the rivet section 17 is furthermore pressed against the reshaping geometry 91 such that material of the rivet section 17 is radially outwardly reshaped to engage behind material of the workpiece 70 adjoining the punched hole and, in this way, to form an axially acting undercut 43 closed in the peripheral direction. In the reshaping process, the rivet section 17 is placed closely around the punched margin 77 and produces a flange at the punched margin 77, as FIGS. 5 and 6 clearly show.

[0058] Furthermore, in the assembly region 79, the material of the workpiece 70 is pressed against an elevated portion 95 of the die 90 surrounding the reshaping geometry 91 and directed opposite to the punching direction S such that a recess 81 is produced in the assembly region 79, in which recess 81 the reshaped rivet section 17 and the punching pilot 25 are received in the punching direction S, see in particular FIG. 6.

[0059] Consequently, the component assembly 100 described can be manufactured by means of the functional element 10 in a self-punching manner, i.e. with a relatively small assembly effort. Due to the second punching process using the set-back punching pilot 25, the functional section 13, in particular the internal thread 41, can furthermore be kept free such that a flawless functioning of the functional section 13 is simultaneously ensured.

[0060] Reference numeral list [0061] 10 functional element [0062] 11 head part [0063] 13 functional section [0064] 15 abutment surface [0065] 17 rivet section [0066] 19 free end [0067] 21 first punching edge [0068] 23 second punching edge [0069] 25 punching pilot [0070] 27 gap [0071] 29 outer surface [0072] 31 inner surface [0073] 33 workpiece contact section [0074] 35 first contact surface [0075] 37 second contact surface [0076] 39 feature providing security against rotation [0077] 41 thread [0078] 43 undercut [0079] 45 bore [0080] 70 workpiece [0081] 71 first surface [0082] 73 second surface [0083] 75 slug ring [0084] 77 punched margin [0085] 79 assembly region [0086] 81 recess [0087] 90 die [0088] 91 reshaping geometry [0089] 93 reshaping surface [0090] 95 elevated portion [0091] 96, 97 edge [0092] 98 annular surface [0093] 99 passage [0094] 100 component assembly [0095] A axis [0096] S punching direction