Patent ID: 7856704

Claim:
Apparatus for clinching together first and second stacked sheet metal panels, comprising: a die assembly positioned on one side of the panels and having a button forming cavity defined by an anvil at the bottom of the cavity and a plurality of radially movable die blades at the sides of the cavity, a plunger positioned on the other side of the panels and registered with the die assembly so that linear displacement of the plunger plastically deforms the panels axially into the die assembly until engagement with the anvil terminates axial displacement of the panels and further linear displacement of the plunger deforms the panels radially outward as permitted by the outward radial movement of the movable die blades; a monitoring device including a transducer for measuring at least one of the linear displacement of the plunger, the radial outward displacement of one of the radially movable die blades, and a force applied against the anvil.