Patent ID: 7694399

Claim:
A workpiece joining die comprising: an anvil including a workpiece-interfacing end and at least one side surface, the anvil having a substantially flat workpiece-interfacing end which intersects the at least one side anvil surface at a uniformly shaped corner at all radial cross-sections through the anvil; movable die blades contacting against the at least one side surface of the anvil when in a nominal condition, each of the die blades including an inwardly extending cap overlapping a portion of the workpiece-interfacing end of the anvil when in the nominal condition; and a biasing member operably retaining the die blades and biasing them toward the anvil; each adjacent pair of the caps of the die blades contacting against each other to define a closed shape when in the nominal condition; and the caps of the die blades preventing workpiece material from flowing between the die blades and the at least one side surface of the anvil.