Experimental study of the effects of a change of tool geometry on blanked edges of fine-blanked parts

This paper is to present an experimental study on effects of the change of tool geometry on blanked edges of fine-blanked parts. The most remarkable feature of fine-blanking is the completely smooth edge obtained on the blanked part which can be free of tearing over the whole thickness. However, research on effects of the change of tool geometry on the fine-blanked edges is limited. Therefore, an experimental study was conducted to investigate how the tool geometry affects the fine-blanked edge quality by varying the punch nose radius. Five punches with various nose radii (Rp), 0.00 mm, 0.25 mm, 0.50 mm, 0.75 mm and 1.00 mm were used for fine-blanking parts, whilst the nose radius of the die remained the same throughout the study. Cold-rolled carbon steel sheet (SS400) with thickness of 5 mm was selected for this study. Features of fine-blanked parts such as the blanked edge finish, burr height and die-roll height were measured and reported. It was found that the increase of punch nose radius would reduce the percentage of shear of blanked edge and increase the amount of burr height. As a result, the increase in punch nose radius does implicate the effects on the blanked edge of the fine-blanked parts