Functional element for the attachment to a sheet metal part, component assembly manufactured from these and also a method for the attachment of the functional element to a sheet metal part

A method for the attachment of a functional element to a sheet metal part for the manufacture of a component assembly, wherein the functional element has a body portion comprising a ring flange, a central longitudinal axis, a tubular section and a fastener section, the ring flange having an annular support surface extending generally perpendicular to the longitudinal axis and facing the tubular section, the annular support surface having an outer diameter and an inner diameter, there being a transition from the ring flange into the tubular section, the transition starting from the inner diameter of said annular support surface and being formed by an at least substantially conical surface having a cone angle, which forms a contact surface for a corresponding conical region of a sheet metal part, and there being raised material noses provided on the tubular section of the functional element, the method comprising the steps of:

• manufacturing a conical recess having a cone angle in a sheet metal part by supporting the sheet metal part on a die having a correspondingly shaped recess, by forming the sheet metal part into the conical recess of the die and by piercing the sheet metal part with a free end of the tubular section, thereby providing a hole having a rim and a hole diameter in and concentric to the conical recess, with the hole diameter corresponding at least substantially to the diameter of the tubular section of the functional element or being somewhat larger than this and with the cone angle of the conical recess corresponding at least substantially to the cone angle of the conical surface of the functional element,
• passing the tubular section of the functional element through the hole so that the conical region of the conical recess enters approximately into contact with the conical surface of the functional element and the ring flange enters into engagement with the sheet metal part and so that the fastener section is on a side of the sheet metal part remote from the tubular section and
• displacing material from the raised noses in the direction of the central longitudinal axis towards the body portion of the functional element by means of the die, thereby forming radial projections at the positions of the raised noses, the radial projections contacting the rim of the hole and engaging in form-locked manner into this conical formation and clampingly receiving the conical region of the sheet metal part between the radial projections and the ring flange.