An efficient approach for trimming simulation of 3D forged components

Trimming operation as an important stage of many sheet and bulk metal processes is geometrically and physically complex and computationally challenging. This is especially true for metal forming processes where net-shape specification is critical. In this paper, we present an efficient approach for fast trimming simulation of 3D forged components so that the effect of such trimming operations on post-forming material spingback, thermal distortion and final dimensional and shape accuracy of formed parts can be quantified. This approach comprises steps including definition of trim line, elimination of discarded elements, adjustment of nodal positions close to the trim line and mapping of the state variables from the original mesh to the new mesh. To evaluate the effect of residual stresses in trimming operation, a new algorithm involving a scaling interpolation and coordinate transformation procedure is proposed so that limited 2D trimming simulations can be used to quantify and to map trimming induced residual stresses onto the whole 3D model for further process simulation. This developed trimming simulation approach was verified using an industry case study in hot forging of a 3D aerofoil blade by three post-forging cooling simulation cases including an untrimmed blade, a trimmed blade and a trimmed blade with the inclusion of trimming induced residual stresses. The simulation results were compared with actual measurement data of the forged aerofoil blade with excellent results obtained. The results show that the trimming operation has a significant effect on post-forging springback and thermal distortion but much less so on thickness of the aerofoil sections of the forged blade. The results also demonstrate that the proposed trimming simulation approach is computationally efficient and robust for other bulk and sheet metal forming processes of complex shapes.