Self-attaching fastener and panel assembly, and method of attaching

A fastening element and panel assembly, comprising:

• a hard steel panel having an aperture defined therethrough;
• and
• a self-attaching fastener, including:
• a substantially polyhedral head portion defining a longitudinal axis wherein the head portion is circumscribable by a first cylinder having a head diameter wherein the first cylinder is coaxial to the longitudinal axis;
• a central pilot portion substantially defining a pilot polyhedron extending from the head portion along the longitudinal axis wherein:
• the central pilot portion is circumscribable by a second cylinder having a pilot diameter smaller than the head diameter;
• the second cylinder is coaxial to the longitudinal axis;
• the central pilot portion has a perimetric wall;
• the perimetric wall has rectangular faces of the pilot polyhedron;
• the rectangular faces are defined in respective planes that are parallel to the longitudinal axis;
• and
• the rectangular faces engage complementary faces of the panel defining the polygonal panel aperture to resist relative rotation between the self-attaching fastener and the panel when a predetermined torque is applied to the self-attaching fastener;
• and,
• a planar panel support surface defined on the head portion, wherein the planar panel support surface defines a closed substantially polygonal planar margin at a perimeter of the planar panel support surface;
• wherein:
• the aperture is complementary to the central pilot portion;
• a rim of the central pilot portion is upset outwardly extending over a perimeter of the aperture;
• and
• the upset rim of the central pilot portion retains the self-attaching fastener in the panel against a predetermined pull-out force.

A method of attaching a self-attaching fastener in a panel, comprising:

• forming a substantially polygonal panel aperture in a hard steel panel;
• then aligning a central pilot portion of the self-attaching fastener with the aperture, wherein the self-attaching fastener includes:
• a substantially polyhedral head portion defining a longitudinal axis wherein the head portion is circumscribable by a first cylinder having a head diameter wherein the first cylinder is coaxial to the longitudinal axis;
• the central pilot portion substantially defining a pilot polyhedron extending from the head portion along the longitudinal axis, wherein:
• the central pilot portion is circumscribable by a second cylinder having a pilot diameter smaller than the head diameter;
• the second cylinder is coaxial to the longitudinal axis;
• the central pilot portion has a perimetric wall;
• the perimetric wall has rectangular faces of the pilot polyhedron;
• the rectangular faces are defined in respective planes that are parallel to the longitudinal axis;
• the aligning includes:
• centering the central pilot portion over the aperture such that the longitudinal axis intersects a centroid of the aperture, and is normal to the panel;
• and
• rotating the self-attaching fastener such that each of the rectangular faces is parallel to a respective edge of the polygonal panel aperture;
• and
• the rectangular faces are to engage complementary faces of the panel defining the polygonal panel aperture to resist relative rotation between the self-attaching fastener and the panel when a predetermined torque is applied to the self-attaching fastener,
• wherein:
• a rim is defined at a leading end of the perimetric wall;
• the rim has a planar end face at a leading end of the rim corresponding to the leading end of the perimetric wall;
• the rim has an inner wall opposite to the perimetric wall;
• the inner wall defines a chamfer such that a leading end of the rim is narrower than a base of the rim at an interface of the rim with a body of the central pilot portion;
• and,
• the body of the central pilot portion is at least twice as thick as the end face of the rim measured along respective lines orthogonal to the longitudinal axis;
• and
• a planar panel support surface defined on the head portion, wherein the planar panel support surface defines a closed substantially polygonal planar margin at a perimeter of the planar panel support surface;
• then seating the self-attaching fastener in the panel aperture such that the panel contacts the planar panel support surface;
• and
• then pressing the rim of the central pilot portion with less than 12 tons of force via a die driven by a press, thereby upsetting the rim outwardly to extend over a perimeter of the aperture to retain the self-attaching fastener in the panel against a predetermined pull-out force.

A self-attaching fastener, comprising:

• a substantially polyhedral head portion defining a longitudinal axis;
• having a head diameter wherein the first cylinder is coaxial to the longitudinal axis;
• a central pilot portion substantially defining a pilot polyhedron extending from the head portion along the longitudinal axis, wherein:
• the central pilot portion is circumscribable by a second cylinder having a pilot diameter smaller than the head diameter;
• the second cylinder is coaxial to the longitudinal axis;
• the central pilot portion has a perimetric wall;
• the perimetric wall has rectangular faces of the pilot polyhedron;
• and
• the rectangular faces are defined in respective planes that are parallel to the longitudinal axis;
• a planar panel support surface defined on the head portion, wherein the planar panel support surface defines a closed substantially polygonal planar margin at a perimeter of the planar panel support surface;
• and,
• a rim defined at a leading end of the perimetric wall and having an inner wall opposite to the perimetric wall;
• wherein the inner wall defines an interior chamfer such that the leading end of the rim is narrower than a base of the rim at an interface of the rim with a body of the central pilot portion.

A self-attaching fastener, comprising:

• a substantially polyhedral head portion defining a longitudinal axis;
• having a head diameter wherein the first cylinder is coaxial to the longitudinal axis;
• a central pilot portion substantially defining a pilot polyhedron extending from the head portion along the longitudinal axis wherein:
• the central pilot portion is circumscribable by a second cylinder having a pilot diameter smaller than the head diameter;
• the second cylinder is coaxial to the longitudinal axis;
• the central pilot portion has a perimetric wall;
• the perimetric wall has rectangular faces of the pilot polyhedron;
• and
• the rectangular faces are defined in respective planes that are parallel to the longitudinal axis;
• and,
• a planar panel support surface defined on the head portion, wherein the planar panel support surface defines a closed substantially polygonal planar margin at a perimeter of the planar panel support surface;
• wherein the substantially polyhedral head portion is substantially a regular hexagonal prism chamfered at longitudinal edges of the regular hexagonal prism;
• and the pilot polyhedron is substantially an other regular hexagonal prism chamfered at longitudinal edges of the other regular hexagonal prism.

A self-attaching fastener, comprising:

• a substantially polyhedral head portion defining a longitudinal axis;
• having a head diameter wherein the first cylinder is coaxial to the longitudinal axis;
• a central pilot portion substantially defining a pilot polyhedron extending from the head portion along the longitudinal axis wherein:
• the central pilot portion is circumscribable by a second cylinder having a pilot diameter smaller than the head diameter;
• the second cylinder is coaxial to the longitudinal axis;
• the central pilot portion has a perimetric wall;
• the perimetric wall has rectangular faces of the pilot polyhedron;
• and
• the rectangular faces are defined in respective planes that are parallel to the longitudinal axis;
• and,
• a planar panel support surface defined on the head portion, wherein the planar panel support surface defines a closed substantially polygonal planar margin at a perimeter of the planar panel support surface;
• wherein the substantially polyhedral head portion is substantially a regular hexagonal prism with fillets at longitudinal edges of the regular hexagonal prism;
• and
• the pilot polyhedron is substantially an other regular hexagonal prism with fillets at longitudinal edges of the other regular hexagonal prism.