Investigation of Combined Flat Coining and Fine Blanking of 16MnCr5 to Influence the Die Roll Formation

The die roll height and width are quality-determining attributes of fine blanked parts that reduce the load-bearing capacity of functional surfaces. Depending on the blanked part requirements, a sheet thickness allowance is necessary to compensate the surface reduction, which must be removed by a downstream process step. Combining flat coining and fine blanking into a progression process offers the possibility of specifically influencing the material properties of functional areas of the blanked part. Due to an influence of the strength on the die roll formation, a local strain hardening of the shear zone has the potential to reduce the die roll and consequently the post-processing effort. Hence, the influence of pre-hardening by upsetting on the fine blanking process for case hardening steel 16MnCr5 was analyzed in an experimental investigation. It could be demonstrated that the die roll formation is significantly reduced due to near-surface strain hardening in the area of the shear zone.