An Effective Coaxiality Measurement for Twist Drill Based on Line Structured Light Sensor

Aiming at the accurate and effective coaxiality measurement of twist drills with irregular surface, an optical measurement mechanism is proposed in this article. First, a high-precision rotation instrument based on four core units is designed, which can obtain 3-D point cloud data of twist drills at all angles. Second, in the data processing stage, an improved robust Gaussian mixture model is proposed for accurate and rapid blade back segmentation. To improve the measurement efficiency, a rapid reconstruction method of twist drill axis based on orthogonal synthesis is proposed, which can rapidly locate the maximum deviation between the actual axis and the reference by using the extracted blade back data. Finally, by calculating the maximum radial Euclidean distance from the benchmark, the coaxiality error of the twist drill is obtained. Compared with other measurement methods, the experimental results show that our proposed method performs well with high efficiency of less than 3 s/pc and the average measurement error is about 0.020 mm. The experimental results and uncertainty analysis show that the proposed method is effective and automatic and can be applied to the coaxiality measurement of twist drills of various specifications.