20th International Forgemasters Meeting - IFM 2017

Open-die forging is an incremental bulk metal forming process, which is mainly used for the production of long and straight workpieces with simple geometries. The production of complex geometries usually requires additional manufacturing steps or can only be realised by a high amount of machining. A new and innovative manufacturing approach is based on the idea to realise the production of complex workpieces through superimposed manipulator displacements during a forging stroke. Due to the plastic state of stress during a stroke, already relatively small superimposed forces are sufficient to form the workpieces towards the intended geometry. This new open-die forging process is based on the idea, that the manipulator is used to actively control the material flow and form the workpiece towards the intended geometry. Since usually the manipulator is not designed to actively form the material, in a first step a new kinematic concept was developed which allows the required movements during forging. This kinematic concept was successfully transferred to the industrially open-die forging setup at IBF. Based upon this, the influence of different process parameters on the final geometry is discussed by numerical simulation and experimental validation. Besides the common forging parameters as bite ratio and height reduction, the bending angle, bending velocity and bending direction have a decisive influence on the resulting workpiece geometry. Both the numerical and experimental investigation prove that the new process concept can be used to drastically increase the range of producible geometries in open-die forging and therefore could offer a promising approach to realize the near net shape production of complex workpieces. Keywords: Open-die forging; bending; Manipulator; Curved workpieces; Stress superposition