Development of process control in sheet metal forming

In sheet metal forming processes, the blank holder force controls the material flow into the die cavity, which is critical to producing a good part. Process control can be used to adjust the blank holder force in-process based on tracking a reference punch force trajectory to improve part quality and consistency. Key issues in process control include process controller and reference punch force trajectory design. The purpose of this paper is to present a systematic approach to the design and implementation of a suitable process controller and an optimal reference punch force trajectory. The approach includes modeling of the sheet metal forming process, design of the process controller, and determination of the optimal punch force trajectory. Experimental results from U-channel forming show that a suitable process controller can be designed through simulation and an optimal reference punch force trajectory can be synthesized through experiments. The proposed development should be useful in designing and implementing process control in sheet metal forming processes.