Patent ID: 7731467

Claim:
A one-piece functional male element formed as a single piece of metal adapted for use with a metal panel element of steel of drawing quality, and comprising: a solid shaft part with first and second ends; said shaft part merging at said first end into a head part axially aligned with said shaft part, said head part forming a hollow tubular wall adapted for forming a rivet joint with a pre-pierced panel element under the action of pressing forces applied to said shaft part; wherein the shaft part has a spherical formation with a ball diameter at said second end, said shaft part having an at least substantially constant diameter over at least its total length from said spherical formation up to said head part and said ball diameter being larger than said shaft diameter; said male element being formed of a material which in the context of cold deformation achieves at least the strength values of class 5.6 in accordance with the ISO standard 898/1, dated August 1999.