An adaptive laser focus auto-positioning method for non-datum complex components based on 3D vision

Abstract

For the advantages of high single-pulse energy and non-contact processing, laser is used to process easily deformable, high-hardness, and high-brittle materials. For some rough, easily deformed, and no-datum workpieces, it is difficult to locate the laser focus on the machining datum, resulting in processing deviation. This paper aims to solve the problem of automatic positioning of the laser focus on complex workpieces without positioning datum in three-dimensional laser processing. A calibration method of 3D scanner and five-axis laser machine tool is proposed, which combines the laser-processed circular hole, calibration ball and the virtual geometric features formed by the high-precision movement of the machine tool as the calibration objects. Based on the calibration results and the principle of homogeneous coordinate transformation, the kinematic model of five-axis laser machine tool is established dynamically. Then, according to the geometric information of the key points obtained by visual measurement, the automatic positioning of the laser focus on non-datum complex components is realized. Finally, the method proposed in this paper is verified by using planar ceramic components and non-datum complex ceramic components as positioning objects respectively. The results show that the method provided in this paper can effectively realize the automatic positioning of laser focus for non-datum complex components. And the positioning error is less than 45µm. The method proposed in this paper has been applied in the actual ceramic core trimming.