Analysis of process forces and geometrical correlations for open-die forging with superimposed manipulator displacements

The production of curved shaped parts in open-die forging requires additional manufacturing steps, complex tool setups or a high amount of machining. A new approach realizes the process-integrated production of complex workpieces through the superposition of stresses during forging. Here, the forging manipulator is used to actively control the material flow towards the intended final geometry. The investigations aim at an analysis of the forging process regarding bending forces and the correlation of process parameters and the resulting geometry. Following an introduction of the process, a semi-empiric model is proposed and validated, which allows to calculate the bending force depending on the process parameters. Besides the bending forces, the workpiece geometry is further analyzed and a model for the material flow is proposed and validated by experiment and numerical simulation. Based upon these validated models for bending force and geometry, the process concept is transferred to a scaled industrial geometry with non-constant bending radii. Both numerical and experimental investigations prove that the concept can be used to increase the range of geometries, since the bending forces and the resulting geometries only small deviations between the proposed models, numerical simulation and experimental validation were observed. Altogether, the results indicate that the models can be applied to realize a process design for the production of curved workpieces by combined forging and bending to realize the near net shape forging of complex workpieces.