Study on surface fitting algorithm applied in manufacturing of CFETR VV

Abstract During the manufacturing process of China Fusion Engineering Test Reactor vacuum vessel mock-up, the dimensional accuracy and the contour accuracy of the vacuum vessel decrease inevitably due to manufacturing and assembly errors. To solve this problem, measuring and fitting method is used and new reference points are established. For nonuniform distribution of deviations caused by the asymmetric structure of the vacuum vessel sector, least square algorithm is improved by introducing weight factors from the least squares method. With the improved fitting algorithm, the error distributions of simulation results and deviations after fitting of the 1/32 vacuum vessel sector become more even, and the error maximums are reduced. Results show that measuring and fitting method with improved algorithm is effective in improving the manufacturing errors of vacuum vessel sectors and can be used as a reference for manufacturing of other vacuum vessels.