Experimental study on large deformation in fine-blanking process by implementing different stripper designs: Vee-ring type vs. plate-type

This paper is to present an experimental strain analysis on material deformation in fine-blanking process by implementing the stripper design of vee-ring type as well as the plate-type. Experiments have been performed under different combinations of die clearance and blank holding force by using different types of stripper configuration. Square grid pattern is photo-etched on the cross-section of a pair of axisymmetrical cold rolled steel specimens. On the basis of matrix algebra, finite strains and rotations due to the fine-blanking operation using different types of stripper design configuration are determined from their distorted grid patterns. The distributions of the rotation, the direction of principal finite strain and the principal finite strain along the radial direction of the specimen are obtained. In addition a certain distribution of surface hardness of the fine-blanked specimen is also studied under the situation of using the vee-ring type stripper and the plate-type stripper. The experimental result shows that either using the vee-ring type stripper or the plate-type stripper, the blank holding force and the die clearance play important roles on the deformation behaviour in fine-blanking.