why are clearance and shear angles provided in press tool punch
Answers
http://www.oocities.org/toolanddiemaking/presstools/cuttingclearance.html
The 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.