Measurement-based geometric reconstruction for milling turbine blade using free-form deformation

In aerospace engineering, the combination of hot forming and numerical control milling processes is an effective way to manufacture gas turbine blades nowadays. Due to the shape deviation, it is hard to mill the parts formed by hot forming process to the final nominal shape sometimes. To reduce the rejection rate and save the production cost, a measurement-based approach for geometric reconstruction of final nominal shape using free-form deformation (FFD) is presented in this paper. The original shape was firstly sliced into several cross-sections in its design manner, then each section was modified by FFD based on a set of organized measurement points, and at last the final nominal shape was reconstructed by lofting these modified cross-sections. An iteration process with knot insertion was developed to improve the FFD calculation accuracy. The results were found to be highly encouraging, which validates the feasibility of our proposed geometrical reconstruction method.