Patent ID: 7387006

Claim:
A sensing system for a sheet metal forming tool that is loaded with a blank, the sheet metal forming tool has an upper die that is reciprocally moved relative to a lower die in a drawing cycle, the sensing system comprising: a blank holder assembly onto which the blank is loaded, the blank holder assembly has a support member on which the blank nests when loaded into a design position on the blank holder assembly; a proximity sensor is attached to the blank holder assembly in a location adjacent to the support member; a fluid cylinder having an extensible rod supports the blank holder and proximity sensor, the rod is moved by the cylinder between a raised position and a lowered position, wherein the fluid cylinder biases the rod toward the upper position and the upper die operatively applies an opposing force to the bias of the cylinder and causes the blank holder and proximity sensor to be moved to the lowered position; and wherein the proximity sensor senses that an edge of the blank is located on the blank holder throughout the drawing cycle.