Die for self piercing rivet

A die for use with a self-piercing rivet fastening device including a punch operable for driving a self-piercing rivet, with a large-diameter head and hollow cylindrical legs extending down from the head, into a first and a second fastened members arranged on top of the die, and the die comprises:

• a cavity formed in an upper surface of the die, the cavity including a concave spherical surface defining a single radius (R) centered on a central axis of the cavity.

A die for use in a self-piercing rivet fastening device wherein a punch drives a self-piercing rivet, with a large-diameter head and a hollow cylindrical legs extending down from the head, into a first and a second fastened members arranged on top of the die, and the die comprises:

• a die body defining an axis and partially defining a cavity open in an axial upward direction toward the punch, the die body including an upper surface, a central bottom surface axially below the upper surface and facing the axially upward, and an inclined surface radially between the bottom surface and the upper surface of the die, and wherein an inclination angle (θ) of the inclined surface from the upper surface of the die is in the range including 7° to 15°.

A die for use in a self-piercing rivet fastening device wherein a punch drives a self-piercing rivet, with a large-diameter head and a hollow cylindrical legs extending down from the head, into a first and a second fastened members arranged on top of the die, and the die comprises:

• a die body partially defining a cavity open upwards toward the punch around a central axis, the die body including an upper surface, and a concave spherical surface having a single radius centered on the central axis of the cavity.