A global-to-local registration and error evaluation method of blade profile lines based on parameter priority

Presently, the quality evaluation of long blade profile is still mainly based on the specific cross section, focusing on the twist, position, and profile errors. However, the common registration methods of blade profiles only focus on profile error and ignore other important parameters, which may results in misjudgment of qualified blade or increasing the scrap rate. So, a new global-to-local registration and error evaluation method for a long blade is proposed in this paper. Based on the parameter priority, the registration of the blade is completed from global fine registrations to local fine registrations. The best-fit algorithm is used for global fine registration to screen out the qualified blades firstly. Then, the unqualified results are further optimized by the coordinate alternation method in the local fine registration to guarantee the evaluation result qualified as far as possible. The experimental results show that the proposed method reduces the misjudgment effectively by keeping the more important parameters in the tolerance range. And it is beneficial and practical to guide blade finish machining or repairing because the difficult finish machining or repairable machining parameters are priority to guarantee in the allowable error range.