Fastening element for a friction-welded joint

1. A rotationally symmetrical fastening element comprising:

a shank having a predetermined length, said shank includes a proximal end and a distal end;

an axially centralized rounded tip formed on the distal end of said shank, said axially centralized rounded tip to be included in a friction-welded joint with a flat component;

a truncated conical lateral surface adjoining the tip, said truncated conical lateral surface extending a predetermined distance towards the proximal end of the shank;

a radially extending flange extending outwardly from said shank;

a shoulder formed at an end of the radially extending flange;

a flute formed between said radially extending flange and a large diameter end of the conical lateral surface for receiving material melted during formation of the friction-welding joint, wherein said shoulder surrounds the flute, is axially recessed in relation to the tip and is included in the friction-welded joint;

wherein the truncated conical lateral surface is formed with straight lines which intersect at an imaginary vertex V which is located beyond the rounded tip,

wherein the truncated conical lateral surface is configured with an axial length H 2 between the imaginary vertex V and a distal surface of the shoulder, and an axial length H 1 between the imaginary vertex V and where the large diameter end of the truncated conical lateral surface transitions to the flute, and the large diameter end of the truncated conical lateral surface has a dimension D 1 perpendicular to an axis of the shank which is greater than the length H 1 ,

wherein said shoulder limits the movement of the fastening element during formation of the friction-welded joint without penetration through the flat component.

2. Fastening element according to claim 1 , wherein the shoulder is curved in form.

3. Fastening element according to claim 2 , wherein disposed between flute and shoulder is an annular projection, said annular projection being convex in cross section.

4. Fastening element according to claim 2 , wherein the truncated conical lateral surface, which surrounds the tip and is tapered towards the flute, is provided in the central region of its axial elevation with a concentric, wave-shaped step.

5. Fastening element according to claim 2 , wherein the flat component is a single flat component, and the friction-welded joint is formed on only one surface of the single flat component without penetration through an opposite surface of the single flat component.

6. Fastening element according to claim 2 , wherein a channel directly surrounding the tip, wherein the outer annular wall of said channel transitions into the truncated conical lateral surface.

7. Fastening element according to claim 2 , wherein the dimension D 1 is greater than the length H 2 .

8. Fastening element according to claim 1 , wherein the shoulder is flat in form.

9. Fastening element according to claim 8 , wherein disposed between flute and shoulder is an annular projection, said annular projection being convex in cross section.

10. Fastening element according to claim 8 , wherein the truncated conical lateral surface, which surrounds the tip and is tapered towards the flute, is provided in the central region of its axial elevation with a concentric, wave-shaped step.

11. Fastening element according to claim 1 , wherein disposed between flute and shoulder is an annular projection, said annular projection being convex in cross section.

12. Fastening element according to claim 11 , wherein disposed between annular projection and shoulder is a concentrically circular groove.

13. Fastening element according to claim 1 , wherein the truncated conical lateral surface, which surrounds the tip and is tapered towards the flute, is provided in the central region of its axial elevation with a concentric, wave-shaped step.

14. Fastening element according to claim 1 , wherein a channel directly surrounding the tip, wherein the outer annular wall of said channel transitions into the truncated conical lateral surface.

15. Fastening element according to claim 1 , wherein the truncated conical lateral surface has a plurality of axially extending edges.

16. Fastening element according to claim 1 , wherein the fastening element is formed as a bolt.

17. Fastening element according to claim 16 , wherein the tip with its flute, the annular projection and the shoulder are constituent parts of a radial flange projecting from the shank of the bolt.

18. Fastening element according to claim 1 , wherein the fastening element is formed as a nut.

19. Fastening element according to claim 1 , wherein the flat component is a single flat component, and the friction-welded joint is formed on only one surface of the single flat component without penetration through an opposite surface of the single flat component.

20. Fastening element according to claim 1 , wherein the dimension D 1 is greater than the length H 2 .