Investigations on Orbital Forming of Sheet Metals to Manufacture Tailored Blanks with a Defined Sheet Thickness Variation

Abstract

Orbital forming is an incremental bulk cold forming process with many advantages. It can produce net-shape or near-net-shape parts that have superior mechanical properties due to work hardening compared to manufacturing with cutting processes or hot forming. In this work the orbital forming process is employed in a closed-die configuration. A rising of the material thickness in the outer areas of a circular sheetmetal blank is enabled by preventing the lateral material flow. The main effects and subsequently the effects of the interaction of parameters were investigated by a two-step design of experiments. A screening plan was used to identify the statistically relevant parameters. The effects were then studied in a subsequent central-composite design of experiments. With the measured data a nonlinear response-surface model was parameterized to describe the dependency of the mould filling on the investigated process parameters. This model was validated experimentally and showed a good agreement to reality. Additionally a new concept for the tool system was developed and investigated. The form-defining cavity can be changed from the upper punch to the counterpunch.