Method of installing self-attaching fasteners

A method of attaching a fastener to a plastically deformable panel, said fastener including a body portion and a self-piercing and riveting annular wall extending from said body portion, said annular wall having an outer surface, an inner surface defining an opening and a free end portion, said annular wall having a piercing surface adjacent said inner surface spaced from the distal end of said free end portion, the method comprising:

• (a) locating said fastener opposite said panel with said annular wall free end portion facing said panel and a die member located on the opposite side of said panel, said die member having a concave die cavity surrounding a projecting central die portion, said central die portion having a generally conical free end portion coaxially aligned with and telescopically receivable within said fastener annular wall opening;
• (b) engaging said fastener annular wall free end portion against said panel and deforming said panel against said central die conical free end portion;
• (c) piercing a slug from said panel with said annular wall piercing surface, and said slug having a diameter greater than said fastener annular wall opening;
• (d) forcing said panel slug into said annular wall opening in firm engagement with said inner surface;
• and
• (e) plastically deforming said fastener annular wall free end portion radially outwardly in said die cavity and plastically deforming the pierced edge of said panel against said annular wall outer surface into engagement with the deformed end of said annular wall free end portion, thereby forming a mechanical interlock between said self-piercing and riveting annular wall and said pierced panel edge.

A method of attaching a fastener to a metal panel, said fastener including a body portion and a self-piercing and riveting annular wall extending from said body portion, said annular wall having an outer surface, an inner surface, a free open end portion, and a piercing surface adjacent said free end portion and said inner surface, the method comprising:

• (a) locating said fastener opposite said panel with said annulas wall free end portion facing said panel and a die member located on the opposite side of said panel;
• (b) piercing a slug from said panel with said annular wall piercing surface;
• (c) said die member carrying said pierced panel slug into said annular wall opening;
• (d) plastically deforming said annular wall free end portion radially outwardly into a generally U-shaped channel with said channel opening toward said body portion and the pierced edge of said panel;
• (e) plastically deforming said pierced panel edge against said annular wall outer surface into said U-shaped channel, driving said pierced panel edge into said U-shaped channel, and plastically deforming the free end of said panel pierced edge and forming a reinforcing enlarged annular bead on said pierced panel edge enclosed within and contacting the inner surface of said U-shaped channel, thereby forming a reinforcing mechanical interlock between said self-piercing and riveting annular wall and said panel.

A method of attaching a nut fastener to a metal panel, said nut fastener having a body portion including a nut bore and a self-piercing and riveting annular wall projecting from said body portion, said annular wall having an opening through the free end portion generally coaxially aligned with said nut bore, the method comprising:

• (a) locating said nut fastener opposite said panel with said annular wall free end portion facing said panel and a die member located on the opposite side of said panel, said die member having an annular die cavity and a projecting central die portion coaxially aligned with and telescopically receivable within said annular wall opening;
• (b) piercing a slug from said panel with said annular wall free end portion and receiving and supporting said panel slug on said projecting central die portion;
• (c) displacing said panel slug into said annular wall opening and retaining said slug on said projecting central die portion in said opening;
• (d) plastically deforming said annular wall free end portion radially outwardly in said annular die cavity and plastically deforming the pierced edge of said panel into a mechanical interlock with said deformed annular wall free end;
• and,
• (e) punching said panel slug out of said annular wall opening.

A method of attaching a self-fastening member to a plastically deformable panel, said self-fastening member including a base portion having a side surface and a bottom surface, an annular wall integrally joined to said base portion bottom surface spaced inwardly from said base portion side surface, and said annular wall having a free open end portion, the method comprising:

• (a) locating said self-fastening member opposite said panel with said annular wall free end portion facing said panel and a die member located opposite said panel, said die member having an annular die cavity surrounding a central projecting die portion and said die member having a relatively flat panel supporting shoulder on opposite sides of said die cavity, the free end of said central die portion coaxially aligned with and telescopically receivable in said self-fastening member annular wall free open end portion and said central die portion free end spaced below the plane of said die member shoulder, said central die portion having a relatively smooth arcuate concave outer die surface extending through the bottom surface of said die cavity, and the outer surface of said annular die cavity including an inwardly inclined die surface extending from adjacent said shoulder into said die cavity and terminating in an annular lip spaced above said die cavity bottom surface;
• (b) supporting said panel on said die member shoulder in fixed relation;
• and,
• (c) relatively moving said self-fastening member and said die member toward each other to perform the following method steps in a continuous operation;
• (1) engaging said panel with said self-fastening member annular wall free end and piercing said fastener free end through said panel and plastically deforming said panel into said annular die cavity,
• (2) telescopically disposing said central die portion into said annular wall free open end portion through an opening pierced in said panel,
• (3) plastically deforming said self-fastening member annular wall free end radially outwardly against said die member central portion arcuate concave outer die surface, and plastically deforming the panel portion adjacent said opening into said die cavity against the outer surface of said annular wall, and
• (4) plastically deforming said self-fastening member annular wall free end radially outwardly into a U-shaped channel in cross-section opening toward said member base portion through said die cavity bottom surface and simultaneously driving said self-fastening member base portion into said panel and counter rotating said panel portion in the developing U-shaped channel of said annular wall free end, forming a mechanical interlock between said annular wall and said panel portion.