Consistency of part dimensions and avoiding breakage are two major press-shop concerns that depend directly on control over forming-system inputs. One key input is blank size, which influences the relative balance between stretch over the punch and blank flow from the binder. Breakage is caused by an oversized blank, while loose material and buckles are created by an undersized blank. Any deviation in blank size affects constancy of part dimensions. Our first press shop shears two contoured blanks (see schematic) from coils ordered with mill edges. The blanks were interwoven to reduce offal and to obtain double the number of blanks per coil handling and setup. The mill edges act as part of the binder during forming and then are trimmed from the final part. Inconsistent blank widths were causing problems in part dimensional control and press-shop productivity.
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