Relationship between the Punch–Die Clearance and Shearing Quality of Progressive Shearing Die

Abstract

This study performed experiments for the progressive shearing die of thin phosphorous bronze sheet to investigate effects of punch materials, punch–die clearance, sheared angle, and number of shearing strokes on burnish band of a sheared surface and burr width of shearing corner. It also analyzed the relationship between height of the burnish band and gravimetric wear rate. The concept of manufacturing tolerance was applied to establish an analytical model of the dimensional tolerance between punch and punch base. It was concluded that after assembling the punch and punch base under the worst conditions, the possible offset of the punch center and the punch–die clearance can be analyzed, and the burr width of the shearing corner can be accessed. Based on the experimental data, four linear predictive models elucidating the characteristics of shearing qualities such as punch–die clearance, punch gravimetric wear rate, and height of the burnish band of a sheared surface can be deduced. Besides, a predictive model of burr width was built by using the least-square method, exponential method, and polynomial regressive method. The result is highly referential to the assessment of sheared products as well as the prediction of tool life.

Keywords:

• Metal shearing
• Progressive shearing die
• Punch–die clearance

ACKNOWLEDGMENTS

The authors gratefully acknowledge the financial support of this research by the National Science Council (Republic of China) under Grant NSC 90-2212-E-237-005.

Notes

^aThe punch sheared angles of six punches adopted in the experiment are all in 30 degrees.