Warm and cold blanking of manganese-boron steel 22MnB5 with different tool geometries

Abstract

Abstract Two main processes for shaping press hardened ultra-high strength steels (UHSS) are laser cutting and cold blanking, which are either cost-intensive and time-consuming or require high blanking force. Therefore, the integration of warm blanking and hot forming in one process represents a possible alternative for shaping UHSS. Due to the integration of various process steps such as forming, blanking and quenching, a reduction of process steps is possible. This leads to a decrease of time and operating costs. Tool load can be reduced as well because of the lower tensile strength of heated steel. However, there are several disadvantages to integrating these process steps. High process temperatures encourage warpage of tool and sheet and therefore an increase in tool and maintenance costs. To investigate the influence of process integration on the blanking and retraction forces and the quality of the cutting surface, several surveys were conducted by one-hole-blanking. One possibility to deal with the disadvantages could be the use of different punch geometries (plane, conical, truncated conical) in combination with different clearances during warm blanking of typical quenched 22MnB5. Characteristic cutting and retraction forces and temperatures as well as parameters of cutting surfaces were measured and analyzed. A variation of the punch geometry and clearance does not give a significant improvement in the forces and quality of the cutting surface. However, for a high part quality with less burr, a plane punch is recommended and a conical or a truncated conical punch may reduce friction induced wear in industrial applications by producing less burnish.