Research On Key Technologies In On-machine Composite Inspecting System Of Machining Center

With the development of advanced manufacturing technology, the requirement for the on-machine inspecting function of machining center is becoming more and more high, which is how to ensure the inspecting accuracy and improve the inspecting efficiency for the long-period processed workpiece with complex features. In order to avoid deficiencies and limitations existed in the current on-machine inspecting mode with the single sensor, an on-machine composite inspecting method is presented, and some key technologies are researched in the composite inspecting system developed. Main contributions are summarized as follows:1. Based on the principle of non-contact and contact inspection applied in reverse engineering, a composite inspecting equipment is designed, which can be integrated in tool magazine of machining center. And, the composite inspecting criterion is introduced. Furthermore, according to the design ideas, the work principle of composite inspecting system is given.2. Mathematical models of inspecting system are established, including the non-contact inspecting model of line structured light vision sensor, contact inspecting model with the inspecting delay, and the mathematical model for the fusion of composite inspecting data.3. Based on the established error database, the G codes modification sheme is proposed so that the positioning error of machining center is compensated effectively. And, the calibration work for parameters related to mathematical models of inspecting system is finished, including calibrations for intrinsic parameters of camera and parameters of light plane by designed plane target with concentric circles, equivalent radius of inspecting sphere calibrated by standard ball, and the calibration for extrinsic parameters of camera indirectly by single concentric circle and standard ball, which bring the fusion of composite inspecting data into effect.4. To guarantee the safety and accuracy of contact inspection in the process of automatic inspection, the composite inspecting planning is proposed based on machining features of workpiece. Firstly, the error compensation work is realized for the point cloud data from non-contact inspection for workpiece. Then, geometric features corresponding to machining items are reconstructed by feature extraction and fitting from the point cloud data compensated. Lastly, the contact inspecting path is planned based on geometric features. And, the feasibility of the plan proposed is verified by composite inspecting experiment.5. The software design of inspecting system is introduced, and the inspecting accuracy of composite inspecting system is presented by the inspecting example, beside that, sources of inspecting error are analyzed and the method of decreasing inspecting error is qualitatively proposed.Finally, further research contents for inspecting system are listed based on the conclusion of the whole work.