Abstract
Modification of the punch geometry can greatly reduce the force necessary to perform the perforation of the belt. This paper presents research on axially non-symmetrical piercing punches – double sheared one and one with a cylindrical bowl. FEM analysis was performed for a variable tip angle β in the 60-150° range for a double sheared punch or a variable bowl radius R in the 5.25-10 mm range and for a constant punch diameter D = 10 mm and TFL10S belt. Based on the obtained results, the influence of the tip angle β (for the double sheared punch) and the bowl radius R (for a cylindrical bowl punch) on the perforation force FP and pneumatic cylinder stroke increase Δs was determined. FEM analysis was used to obtain the perforation force in function of punch displacement characteristics for various tool geometry. Based on the results, the characteristics of the perforation force in function of punch geometrical parameters were determined. Additionally, their application in the punching die design process, where the effective geometrical features of the tools are desired, is presented.