Measurement of Form and Position Error of Small-Diameter Deep Holes Based on Collaboration Between a Lateral Confocal Displacement Sensor and Helical Scanning

In this study, an innovative measurement method integrating lateral confocal technology and composite motion control is proposed to address the physical space constraints and data processing problems in the detection of the shape and position errors in deep holes with large aspect ratios and small diameters. By designing a lateral confocal displacement sensor and a cantilever measuring device, we break through the spatial constraints of ∅6 mm deep-hole inspection and solve the problems of rigidity and surface damage in the traditional contact probe. We constructed an axis-rotation coordinated motion control model and found that the measuring points were densely arranged in a helical trajectory along the inner wall of the hole. We developed the "virtual slicing-B-spline reconstruction" algorithm and used the adaptive motion control algorithm to achieve a more efficient measurement of the hole. The innovative "virtual slicing-B-spline reconstruction" algorithm, using adaptive grouping, dynamic slicing, and a fourth-order B-spline-fitting hierarchical processing framework, reached a straightness error assessment result of the 1 μm order. Experiments show that, under 0.5 mm∕s feed rate and 12 rmp rotational speed, the standard deviation of straightness is ≤0.0008 mm and the standard deviation of cylindricity is ≤0.0064 mm; compared to the CMM (coordinate measuring machine) measurement results, the cylindricity and straightness evaluation errors obtained by the new measurement method are reduced by 4.6% and 4.5%, respectively. It provides a technical solution that improves both accuracy and efficiency for the precision inspection of small-diameter deep holes.