  In order to solve the problem of low automation of Aero-engine Turbine shaft
assembly and the difficulty of non-contact high-precision measurement, a
structured light binocular measurement technology for key components of
aero-engine is proposed in this paper. Combined with three-dimensional point
cloud data processing and assembly position matching algorithm, the
high-precision measurement of shaft hole assembly posture in the process of
turbine shaft docking is realized. Firstly, the screw thread curve on the bolt
surface is segmented based on PCA projection and edge point cloud clustering,
and Hough transform is used to model fit the three-dimensional thread curve.
Then the preprocessed two-dimensional convex hull is constructed to segment the
key hole location features, and the mounting surface and hole location obtained
by segmentation are fitted based on RANSAC method. Finally, the geometric
feature matching is used the evaluation index of turbine shaft assembly is
established to optimize the pose. The final measurement accuracy of mounting
surface matching is less than 0.05mm, and the measurement accuracy of mounting
hole matching based on minimum ance optimization is less than 0.1 degree. The
measurement algorithm is implemented on the automatic assembly test-bed of a
certain type of aero-engine low-pressure turbine rotor. In the narrow
installation space, the assembly process of the turbine shaft assembly, such as
the automatic alignment and docking of the shaft hole, the automatic heating
and temperature measurement of the installation seam, and the automatic
tightening of the two guns, are realized in the narrow installation space
Guidance, real-time inspection and assembly result evaluation.
