Abstract: A clinching tool including a punch and a die assembly. The die assembly includes a collet, a pin, and a split bushing. The collet includes a lower base portion and upstanding circumferentially spaced spring fingers. The split bushing is received within the spring fingers and the pin passes upwardly through a central passage in the base portion of the collet and is received at its upper end in the split bushing with the upper end of the pin inset with respect to the upper end of the bushing by a distance related to the thickness of materials to be fastened together. The spring fingers of the collet expand during the clinching operation to allow the material of the sheets to flow radially outwardly to form the desired clinching bead. In a further embodiment, the split bushing is dispensed with and the material of the sheets is allowed to flow radially outwardly between the spaced fingers of a collet so as to form a joint having a plurality of circumferentially spaced fingers or spikes.

Abstract: An apparatus for performing two successive work operations on a workpiece in an equalized force mode. The apparatus includes a base; a yoke mounted for bi-directional movement on the base and carrying a two-sided punch on its upper face; a ram member mounted within the yoke and including two bores opening in opposite faces of the ram member and slidably receiving two pistons secured to the opposite end walls of the yoke; and means for delivering pressurized fluid through the pistons to sealed pressure chambers defined at the inner ends of the pistons between the piston inner ends and the respective confronting faces of the ram to selectively move a pair of die members carried on the upper face of the ram into and out of punching coacting with the double punch carried on the yoke.