| 摘要 |
<p>An improved self-riveting fastening element for permanent attachment to a metal panel within a panel opening by a die member having an annular concave die cavity. The fastening element includes a tubular riveting portion and a radial flange portion and a fastening portion. The internal and external surfaces of the tubular riveting portion are relatively uniformly inclined toward the radial flange portion such that the thickness of the tubular riveting portion at the free end is less than the thickness adjacent the radial flange portion. In the preferred embodiment, the internal surface of the tubular riveting portion is cylindrical and the external surface is slightly conical tapering inwardly toward the free end to reduce the force required to radially deform the free end of the tubular portion radially outwardly. Further, the outer surface of the radial flange portion is generally polygonal having arcuately radially inwardly concave side surfaces spaced by relative thin convex arcuate edge surfaces reducing the force required to drive the flange portion into the panel during final installation of the fastening element.</p> |
