Abstract: For more precise measurement of outer diameter of spun ultra-thin-walled rotational parts, the on-machine measurement of the equivalent outer diameter based on the reconstructed cross section contour curve is proposed. In this method, three sets of line laser displacement sensors are distributed uniformly along the circumferential direction， and the outer contour data of the cross section of rotational part at any axial position is obtained by using the three sets of line laser displacement sensors and the axial movement module of the spinning roller frame. The complete cross section outer contour data is spliced by the coordinate transformation and matching of the cross section data obtained by the three sensors, the contour curve is reconstructed by the shape preserving curve reconstruction method of discrete data points, and the equivalent outer diameter of the cross section is calculated according to length invariance of the same closed curve. Finally, the outer diameters of the mandrel and the thin-walled rotational parts are mea-sured. The experimental results show that the proposed method can be used to precisely measure the outer diameters of ultra-thin-walled rotational parts with measuring accuracy of 0.019 mm. Key

Key words: linelaserdisplacementsensor, datamatching, curvereconstruction, curvelength, equivalentouterdiameter