Die member for attaching a self-piercing and riveting fastener

A die member for attaching self-piercing and riveting fasteners to a panel, said fasteners each including an annular barrel portion having a free open end and a piercing surface adjacent said free end, said die member having an annular concave die cavity configured to receive said fastener annular barrel portion surrounding a projecting central die post, said annular die cavity having a generally smooth annular concave surface, said die post having a free end and an outer surface sloping radially outwardly into said annular concave surface of said die cavity, said die post free end including an outer peripheral piercing surface configured to be received in said barrel portion free end interrupted at spaced locations and said radially outwardly sloping surface of said die post including a plurality of circumferentially spaced cutting edges aligned radially with said interruptions in said die post piercing surface and spaced radially outwardly from said piercing surface of said die post, said piercing surfaces of said die post, said barrel portion and said cutting edges cooperating to pierce a slug from said panel in two stages, first along said piercing surfaces forming a panel slug having radially extending tabs integral with said panel, then said cutting edges severing said tabs, said die post then driving said panel slug into said barrel portion open end deforming said panel slug radial tabs in engagement with an internal surface of said barrel portion staking said panel slug in barrel portion.

A die member for attaching a self-piercing and riveting fastener to a panel, said fastener including an annular barrel portion having a free open end and a piercing surface adjacent said free end, said die member having an annular concave die cavity configured to receive said fastener annular barrel portion free end surrounding a central die post, said annular concave die cavity having a generally smooth U-shaped concave surface, said central die post projecting from said annular die cavity having a free end including a piercing surface configured to be received in said annular barrel portion free open end, and said die post having an outer surface sloping radially outwardly into said U-shaped concave surface of said annular die cavity, and a plurality of staking cavities defined in said central die post free end spaced circumferentially around said die post, each staking cavities opening radially outwardly, said cavities each having a bottom wall intersecting said radially outwardly sloping outer surface of said die post defining a cutting edge spaced below and radially outwardly of said central die post piercing surface, said piercing surface of said central die post and said cutting edges cooperating with said piercing surface of said fastener barrel portion to pierce a slug from a panel overlying said die member as said barrel portion free end is driven into said annular die cavity and said cutting edges cutting and shearing ribbons from an inside surface of said barrel portion as said barrel portion is driven over said central die post outer surface, staking said panel slug in said barrel portion.