Control of the servo-press in stamping considering the variation of the incoming material properties

Abstract

The variation of incoming material properties and the quality of emerging advanced high-strength steels significantly increases the costs for product design and production. It is not economical to tightly control material chemistry to eliminate the variation of material properties at steel mills. This paper introduces a methodology on how to implement a non-destructive evaluation (NDE) tool to measure the variation of the incoming material properties. The servo-controlled forming process was successfully optimized to adapt to variations in the incoming material properties in a lab-scale stamping cell with a 300-Ton mechanical servo press. Final stamping quality was obtained with three different batch materials by altering servo press parameters, such as the slide motion and blank holder force, to adjust for the variation of the material properties from one batch to another. Both a mid-strength (340-MPa tensile strength) steel and a high-strength steel (980-MPa tensile strength) were evaluated in this study. The study shows the effectiveness of an NDE tool to non-destructively measure the sheet material properties and the servo-press control to adjust the press parameters for the variation of the material properties.