SELF-PIERCING RIVET JOINT AND SELF-PIERCING RIVET

Abstract

A self-piercing rivet joint, having at least two components made of formable metallic materials having a strength up to 300 MPa, which are connected to one another in a riveting procedure, in which a self-piercing rivet pierces the first, stamp-side component with a setting force and is driven into the second, die-side component, specifically while maintaining a residual base thickness in the second component and while spreading out the self-piercing rivet to a spreading diameter in the second component. The self-piercing rivet is compressed after the riveting procedure down to 60% of its starting length and the spreading diameter is enlarged up to 140% to 150%, in particular to up to 140% of the rivet shaft diameter, specifically without damaging the self-piercing rivet by self-piercing rivet material cracks.

Claims

1-10. (canceled)

11. A self-piercing rivet joint, comprising at least two components made of formable metallic materials having a strength up to 300 MPa, in particular aluminum materials, which are connected to one another in a riveting procedure, in which a self-piercing rivet pierces the first, stamp-side component with a setting force and is driven into the second, die-side component, specifically while maintaining a residual base thickness in the second component and while spreading out the self-piercing rivet to a spreading diameter in the second component, wherein the self-piercing rivet is compressed after the riveting procedure down to 60% of its starting length and the spreading diameter is enlarged up to 140% to 150%, in particular to up to 140% of the rivet shaft diameter, specifically without damaging the self-piercing rivet by self-piercing rivet material cracks.

12. The self-piercing rivet joint as claimed in claim 11, wherein the still undeformed self-piercing rivet has a cylindrical rivet shaft having an inner curvature, which is open toward the shaft tip and is spherical-cap-shaped in particular, and a rivet head larger in diameter in relation to the rivet shaft diameter, and wherein after the riveting procedure, the self-piercing rivet inner curvature is essentially completely filled up by self-piercing rivet material due to material flow during the riveting procedure, and wherein the shaft tip has an essentially planar end face after the riveting procedure, or a rounded end face having a large radius in relation to the rivet dimensions.

13. The self-piercing rivet joint as claimed in claim 11, wherein the inner curvature, in the undeformed state, protrudes starting from the shaft tip with a curvature depth in the axial direction into the rivet shaft, and wherein the curvature depth is between 10% and 25%, in particular 15%, of the self-piercing rivet total length, and/or wherein the rivet head material thickness, which extends along the rivet longitudinal axis between a rivet head upper side and the inner curvature, is between 75% and 90%, in particular 85%, of the self-piercing rivet total length.

14. The self-piercing rivet joint as claimed in claim 12, wherein the transition between the rivet shaft and the rivet head is formed by a rounded rivet head lower side having uniform head radius, and wherein the rounded rivet head lower side merges tangentially radially outward into a planar, conical rivet head lower side, which extends up to a rivet head boundary, and/or wherein the planar, conical rivet head lower side is set diagonally upward in the direction of the rivet head upper side by a cone angle in relation to a horizontal plane, and wherein the head radius is between 0.8 mm and 2.0 mm, and/or the cone angle is in an order of magnitude of 20°.

15. The self-piercing rivet joint as claimed in claim 11, wherein the self-piercing rivet is a flat head rivet having a planar rivet head upper side, and in that, in the self-piercing rivet joint, the rivet head upper side is aligned surface flush, that is to say without head protrusion, with the surface of the first, stamp-side component, and in particular is not raised in relation to the integral component surface, and wherein a circumferential rivet head boundary extends radially outward between the rivet head lower side and the rivet head upper side over a head lateral height, and wherein the head lateral height is in particular 0.3 mm.

16. The self-piercing rivet joint as claimed in claim 11, wherein on the shaft tip facing away from the rivet head, a ring-shaped circumferential placement edge delimiting the inner curvature is formed, and wherein the placement edge acts as a cutting edge during the riveting procedure, using which, on the one hand, early compression of the self-piercing rivet can be suppressed, and, on the other hand, spreading out of the self-piercing rivet by a predefined spreading amount radially outward is controllable, and wherein a wall of the self-piercing rivet inner curvature and a rivet shaft outer circumference run together at an acute angle, in particular at an edge angle of 45°, at the placement edge, and/or in that the placement edge is rounded with a rounding radius in the range of 0.15 mm.

17. The self-piercing rivet joint as claimed in claim 11, wherein in the undeformed state, the self-piercing rivet total length is 4 to 8 mm, in particular between 4.5 mm and 6.0 mm, the rivet head diameter is 4.5 to 8.5 mm, in particular 5.5 mm or 7.75 mm, and/or the rivet shaft diameter is 2.8 mm to 6.6 mm.

18. The self-piercing rivet joint as claimed in claim 11, wherein the base material of the self-piercing rivet is a wire material made of cold extrusion steel or cold heading steel, and/or wherein the self-piercing rivet has a low strength in comparison to conventional self-piercing rivets, but significantly greater ductility, and wherein the strength of the self-piercing rivet in the starting state without strain hardening is between 600 MPa and 1000 MPa, in particular between 750 MPa and 900 MPa.

19. The self-piercing rivet joint as claimed in claim 11, wherein the material thickness ratio between the first, stamp-side component and the second, die-side component is between 1:1 and 1:3, and in that in particular the material thickness of the first, stamp-side component is less than or equal to 1.3 mm.

20. A self-piercing rivet for a self-piercing rivet joint as claimed in claim 11.

21. The self-piercing rivet joint as claimed in claim 13, wherein the transition between the rivet shaft and the rivet head is formed by a rounded rivet head lower side having uniform head radius, and wherein the rounded rivet head lower side merges tangentially radially outward into a planar, conical rivet head lower side, which extends up to a rivet head boundary, and/or wherein the planar, conical rivet head lower side is set diagonally upward in the direction of the rivet head upper side by a cone angle in relation to a horizontal plane, and wherein the head radius is between 0.8 mm and 2.0 mm, and/or the cone angle is in an order of magnitude of 20°.

22. The self-piercing rivet joint as claimed in claim 12, wherein the self-piercing rivet is a flat head rivet having a planar rivet head upper side, and in that, in the self-piercing rivet joint, the rivet head upper side is aligned surface flush, that is to say without head protrusion, with the surface of the first, stamp-side component, and in particular is not raised in relation to the integral component surface, and wherein a circumferential rivet head boundary extends radially outward between the rivet head lower side and the rivet head upper side over a head lateral height, and wherein the head lateral height is in particular 0.3 mm.

23. The self-piercing rivet joint as claimed in claim 13, wherein the self-piercing rivet is a flat head rivet having a planar rivet head upper side, and in that, in the self-piercing rivet joint, the rivet head upper side is aligned surface flush, that is to say without head protrusion, with the surface of the first, stamp-side component, and in particular is not raised in relation to the integral component surface, and wherein a circumferential rivet head boundary extends radially outward between the rivet head lower side and the rivet head upper side over a head lateral height, and wherein the head lateral height is in particular 0.3 mm.

24. The self-piercing rivet joint as claimed in claim 14, wherein the self-piercing rivet is a flat head rivet having a planar rivet head upper side, and in that, in the self-piercing rivet joint, the rivet head upper side is aligned surface flush, that is to say without head protrusion, with the surface of the first, stamp-side component, and in particular is not raised in relation to the integral component surface, and wherein a circumferential rivet head boundary extends radially outward between the rivet head lower side and the rivet head upper side over a head lateral height, and wherein the head lateral height is in particular 0.3 mm.

25. The self-piercing rivet joint as claimed in claim 12, wherein on the shaft tip facing away from the rivet head, a ring-shaped circumferential placement edge delimiting the inner curvature is formed, and wherein the placement edge acts as a cutting edge during the riveting procedure, using which, on the one hand, early compression of the self-piercing rivet can be suppressed, and, on the other hand, spreading out of the self-piercing rivet by a predefined spreading amount radially outward is controllable, and wherein a wall of the self-piercing rivet inner curvature and a rivet shaft outer circumference run together at an acute angle, in particular at an edge angle of 45°, at the placement edge, and/or in that the placement edge is rounded with a rounding radius in the range of 0.15 mm.

26. The self-piercing rivet joint as claimed in claim 13, wherein on the shaft tip facing away from the rivet head, a ring-shaped circumferential placement edge delimiting the inner curvature is formed, and wherein the placement edge acts as a cutting edge during the riveting procedure, using which, on the one hand, early compression of the self-piercing rivet can be suppressed, and, on the other hand, spreading out of the self-piercing rivet by a predefined spreading amount radially outward is controllable, and wherein a wall of the self-piercing rivet inner curvature and a rivet shaft outer circumference run together at an acute angle, in particular at an edge angle of 45°, at the placement edge, and/or in that the placement edge is rounded with a rounding radius in the range of 0.15 mm.

27. The self-piercing rivet joint as claimed in claim 14, wherein on the shaft tip facing away from the rivet head, a ring-shaped circumferential placement edge delimiting the inner curvature is formed, and wherein the placement edge acts as a cutting edge during the riveting procedure, using which, on the one hand, early compression of the self-piercing rivet can be suppressed, and, on the other hand, spreading out of the self-piercing rivet by a predefined spreading amount radially outward is controllable, and wherein a wall of the self-piercing rivet inner curvature and a rivet shaft outer circumference run together at an acute angle, in particular at an edge angle of 45°, at the placement edge, and/or in that the placement edge is rounded with a rounding radius in the range of 0.15 mm.

28. The self-piercing rivet joint as claimed in claim 15, wherein on the shaft tip facing away from the rivet head, a ring-shaped circumferential placement edge delimiting the inner curvature is formed, and wherein the placement edge acts as a cutting edge during the riveting procedure, using which, on the one hand, early compression of the self-piercing rivet can be suppressed, and, on the other hand, spreading out of the self-piercing rivet by a predefined spreading amount radially outward is controllable, and wherein a wall of the self-piercing rivet inner curvature and a rivet shaft outer circumference run together at an acute angle, in particular at an edge angle of 45°, at the placement edge, and/or in that the placement edge is rounded with a rounding radius in the range of 0.15 mm.

29. The self-piercing rivet joint as claimed in claim 12, wherein in the undeformed state, the self-piercing rivet total length is 4 to 8 mm, in particular between 4.5 mm and 6.0 mm, the rivet head diameter is 4.5 to 8.5 mm, in particular 5.5 mm or 7.75 mm, and/or the rivet shaft diameter is 2.8 mm to 6.6 mm.

30. The self-piercing rivet joint as claimed in claim 13, wherein in the undeformed state, the self-piercing rivet total length is 4 to 8 mm, in particular between 4.5 mm and 6.0 mm, the rivet head diameter is 4.5 to 8.5 mm, in particular 5.5 mm or 7.75 mm, and/or the rivet shaft diameter is 2.8 mm to 6.6 mm.

Description

[0021] In the figures:

[0022] FIG. 1 shows a microsection of a self-piercing rivet in the undeformed state;

[0023] FIG. 2 shows a rough schematic illustration of a self-piercing rivet located in a setting tool before carrying out the setting process; and

[0024] FIG. 3 shows a self-piercing rivet joint.

[0025] FIG. 3 shows a finished self-piercing rivet joint, in which a stamp-side aluminum plate part 1 and a die-side aluminum plate part 3 are connected to one another by means of a self-piercing rivet 5. The two aluminum plate parts 1 have approximately equal material thicknesses s.sub.1, s.sub.2 in FIG. 2 or 3. The self-piercing rivet 5 has a rivet head 7 and a rivet shaft 9. In the figures, the self-piercing rivet 5 is implemented as a flat head rivet having a level, plane-parallel rivet head upper side 17. The rivet head upper side 17 is aligned surface-flush with the surface of the component 1 in FIG. 3.

[0026] To prepare the setting process, the two components 1, 3 are placed on a die 11 of the setting tool lying one on top of another and compressed by means of a hold-down system (not shown) using a hold-down force. Subsequently, the self-piercing rivet 5 is driven by means of a stamp 13 using a setting force F into the two components 1, 3. During the setting process, the self-piercing rivet 5 pierces the material of the stamp-side component 1 and is driven therein up into the second component 3, specifically while maintaining a residual base thickness r (FIG. 3) of the stamp-side component 3 and with spreading out of the self-piercing rivet 5 to a spreading diameter d.sub.A in the second component 3 to create an undercut.

[0027] In the following, the self-piercing rivet 5 alone is described on the basis of FIG. 1: Accordingly, the rotationally-symmetrical self-piercing rivet 5 has an open, spherical-cap-shaped inner curvature 15 open toward the shaft tip, which protrudes with a curvature depth tin the axial direction into the rivet shaft 9. The curvature depth tin FIG. 1 is 15% of the self-piercing rivet total length I. Vice versa, the rivet head material thickness m.sub.K, which extends along the rivet longitudinal axis L between a rivet head upper side 17 and the inner curvature 15, is 85% of the self-piercing rivet total length I. The transition between the rivet shaft 9 and the rivet head 7 is formed in FIG. 1 by a rounded rivet head lower side 16 having uniform head radius d.sub.K, which is 1 mm, for example. The rounded rivet head lower side 16 merges tangentially radially outward into a level, conical rivet head lower side, which extends to a rivet head edge 19. In FIG. 1, the level, conical rivet head lower side is set diagonally upward in the direction of rivet head upper side 17 by a cone angle α (FIG. 1) of approximately 20° in relation to a transverse plane. The radially outer circumferential rivet head edge 19 extends with a head lateral height I.sub.K of approximately 0.3 mm between the rivet head lower side 16 and the rivet head upper side 17.

[0028] A ring-shaped circumferential placement edge 21 delimiting the inner curvature 15 is formed on the shaft tip facing away from the rivet head 7. An inner wall 23 of the self-piercing rivet inner curvature 15 and a rivet shaft outer circumference run together at an acute angle at the placement edge 21, specifically at an edge angle β of approximately 45°. The placement edge 21 is rounded in FIG. 1 with a rounding radius r.sub.a of 0.15 mm.

[0029] In FIG. 1, the total length I of the self-piercing rivet 5 in the undeformed state is 5 mm, the rivet head diameter d.sub.K is 5.5 mm, and the rivet shaft diameter d.sub.S is 2.9 mm. The base material of the self-piercing rivet 5 is a cold heading steel. Its strength in the starting state without strain hardening is 750 to 900 MPa.

[0030] The comparatively low strength of the self-piercing rivet 5 results, in combination with the above-described self-piercing rivet geometry, in a special self-piercing rivet compression behavior, in which the self-piercing rivet 5 is compressed after the setting process to 60% of its starting length I (FIG. 2) and the spreading diameter d.sub.A is enlarged to 135% to 150% of the rivet shaft diameter d.sub.S, without material cracks occurring in the self-piercing rivet 5. As can furthermore be seen from FIG. 3, after the setting process, the self-piercing rivet inner curvature 15 is essentially completely filled up by the self-piercing rivet material due to material flow. The shaft tip of the self-piercing rivet 15 is therefore an essentially planar end face in FIG. 3.

LIST OF REFERENCE SIGNS

[0031] 1 stamp-side component [0032] 3 matrix-side component [0033] 5 self-piercing rivet [0034] 7 rivet head [0035] 9 rivet shaft [0036] 11 die [0037] 13 stamp [0038] 15 inner curvature [0039] 16 rivet head lower side [0040] 17 rivet head upper side [0041] 19 rivet head boundary [0042] 21 placement edge [0043] 23 inner wall [0044] d.sub.S rivet shaft diameter [0045] d.sub.K rivet head diameter [0046] d.sub.A spreading diameter [0047] r.sub.K head radius [0048] α cone angle [0049] β placement edge angle [0050] r.sub.A rounding angle of the placement edge [0051] I self-piercing rivet total length [0052] I.sub.K head lateral height [0053] m.sub.K rivet head material thickness [0054] t curvature depth of the inner curvature [0055] r residual base thickness [0056] L self-piercing rivet longitudinal axis [0057] s.sub.1, s.sub.2 material thicknesses [0058] setting force