Patent ID: 8919175

Claim:
A press working die assembly for forming a negative angle, comprising: a pad secured to an upper die holder being freely movable upward and downward and configured to hold a workpiece; a machining slide cam having cam surfaces on upper and lower sides and a bending edge on one end side, the machining slide cam being supported on the upper die holder or a lower die holder and being slidable laterally along the cam surfaces; a rotary cam having a bending portion configured to form a negative angle portion on the workpiece, and a cam surface for the machining slide cam and being rotatably supported entirely on the lower die holder for rotation about an axis; and a reciprocating driving apparatus configured to rotate the rotary cam from an original position to a workpiece formation position, wherein the reciprocating driving apparatus includes a driven member, a driving unit operably connected to the driven member to drive the driven member in a reciprocating manner in forward and rearward directions, a slide block operably coupled to the driven member to be moved by the driven member in the forward and rearward directions, the slide block having a front end facing in said forward direction and a rear end facing in said rearward direction, an inclined cam surface provided at said front end of the slide block and configured to press against and cause rotation of the rotary cam from said original position toward said workpiece formation position in a first rotation direction about said axis, and a rotation impelling surface provided at said rear end of the slide block and configured to cause rotation of the rotary cam from said workpiece formation position toward said original position in a second rotation direction, opposite said first rotation direction, about said axis, and a restoring action block fixed to the rotary cam and configured to come into abutment with the rotation impelling surface at said rear end of the slide block, when the slide block is moved in said rearward direction, to restore the rotary cam to said original position, wherein the restoring action block is an inverted U-shaped member that comprises a mounting portion fixed to the rotary cam, and first and second leg column portions projecting from the mounting portion in a direction away from the rotary cam and straddling the driven member of the reciprocating driving apparatus.