Measuring and evaluating geometric errors of an aero-engine blade are a complex research topic. At present, there is not a uniform evaluation criterion and completed strategy in the blade manufacturing industry. This article proposes an effective strategy for measuring and evaluating geometric errors of an aero-engine blade: first, measuring six feature curves and calculating the coordinate transformation value with singular value decomposition to improve the accuracy of blade localization; then, an improved measurement method based on the model offset is introduced to eliminate probe radius compensation errors. Finally, the geometric errors of blade are evaluated using the collected measurement data based on genetic algorithm, and a practical evaluation criterion is provided. The proposed strategy for two aero-engine blades has been performed to demonstrate the effectiveness of the proposed methodology and show that it can prevent false feedback for the underlying manufacturing process for aero-engine blades.

Blades are affected by clamping, cutting forces, and residual stress, thus resulting in warping and distortion because of the thin wall and free surfaces. In this paper, a new process for the control of machining distortion is proposed to eliminate surface errors by using an adaptive dual-arm fixture. First, some causes of distortion by different machining methods are discussed. Second, an adaptive mechanism with eight degrees of freedom is designed to allow the blade to be clamped under an unstressed state and to enable the release of stress at any time. Thereafter, a dual-sphere fixture is designed on the basis of the adaptive mechanism. Finally, by adopting this process based on the adaptive dual-arm fixture, machining distortion is reduced after releasing stress several times. Experimental results show that the process can eliminate 50 % of surface errors in machining. Therefore, a test blade machined by the proposed process will exhibit improved precision.

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