Numerical and experimental investigation on full backward extrusion process in forming of pins from DC04 coil

Abstract. In pursuit of CO2-neutral and resource-efficient production, the trend is increasingly moving towards near-net-shape geometries. In the field of cold forming, sheet-bulk metal forming is particularly suitable, as it combines the advantages of sheet metal forming with those of bulk forming. For preliminary investigations, strip material is used due to its flexibility, while coils are used from an industrial perspective. To gain a fundamental understanding of the process, previous analyses by Henneberg and Merklein [1] have explored the potentials and challenges of a sheet-bulk metal forming process. In order to minimize the losses caused by tool wear in this process, such as machine downtime, it is necessary to make an in-depth investigation of the influencing factors affecting tool quality. For this purpose, the forming process was numerically modeled using the simulation software Simufact.Forming. By determining various influencing factors, which can be inserted as simulation input parameters, the simulation should be generated as close to reality as possible. Upsetting tests are carried out using miniaturized specimens to determine the material properties of the steel DC04. The simulation model is validated via experimental tests conducted on a high-speed press. The quality of the workpiece and tool are studied through the examination of a continuous process. The trends identified in the experimental test are effectively reproduced in the numerical model despite minor deviations. It is shown that monitoring tool wear by analyzing the maximum force, the height of the formed pin and the diameter of the pin structure is relevant for the backward extrusion process.