Correction of eccentricity between punch and die in slight clearance punching of ultra-high strength steel sheets

摘要

An approach for correcting the eccentricity in slight clearance punching of ultra-high strength steel sheets having low ductility was developed to improve the quality of sheared edges of punched holes. In this process, a moving die was employed in order to correct the eccentricity between the punch and die and to ease the setting of tools. The gap between the die and holder allowed the eccentric die to move, and thus the die became concentric after several strikes. For the moving die, the depth of the shiny burnished surface on the sheared edge increased and that of the rough fracture surface decreased. It was found that the application of moving die in slight clearance is indispensable for high quality punching of ultra-high strength steel sheets.