Effect of die edge radius on forming of burnished surface in finish blanking (Observation by digital image correlation)

Abstract

Finish blanking is a process that increases the burnished surface using rounded cutting edge of the tools. In this study, the double-sided blanking was carried out using dies with different radius of cutting edges to investigate the effect of the radius of die cutting edge on forming of the burnished surface. A high-speed camera was used to capture the material deformation during blanking process, and analysis was carried out using Digital Image Correlation (DIC). The following results were obtained from the observation of material deformation during blanking. The length of the burnished surface is increased with increasing the radius of die cutting edge, because the punch stroke when the crack is occurred near the die cutting edge becomes large. When the radius of the die cutting edge is further increased, the crack occurs in the sheet material in contact with the middle of the die cutting edge. Therefore, the burnished surface is increased. The relationship between the mechanism of increasing the burnished surface and the radius of the die cutting edge is clarified. When the radius of the die cutting edge is increased, it becomes difficult to increase the equivalent strain and the maximum principal strain. However, the maximum principal strain in the part of sheet material increases as the part of the sheet material approaches the side of the die.

Keywords

• finish blanking
• digital image correlation
• crack
• burnished surface
• material flow
• deformation