Efficient And Accurate Drilling Technology For Fuselage Circumferential Splice Of Large Aircraft

Circumferential splice drilling is one of the most important stages during the digital assembly of large aircraft fuselage. Since the traditional manual drilling cannot meet the requirements of modern aircraft assembly, a lot of advanced automatic drilling and riveting machines are designed both at home and abroad, to ensure efficiency of the drilling process and quality of the connecting holes, and to reduce the labor intensity of the workers. However, only a few devices, with different merits and defects, are suitable for the mission of circumferential splice drilling, and the core technologies of those systems are grasped by foreign countries. At present, the drilling and riveting work in circumferential splice area at home is still finished mainly by hand. Based on the background, a new kind of circumferential splice drilling machine, which is based on two-layer rail structure and visual measurement system, is proposed and designed by Zhejiang University. This system can realize accurate drilling in the whole area under the case of one-time equipment installation, and provides a feasible solution for circumferential splice drilling problem.Firstly, the research background and significance of the topic are clarified, and the development situation and direction of digital aircraft assembly technology at home and broad is reviewed; the advantages and disadvantages of existing splice drilling systems are also analyzed and compared, which leads to the object and main content of this paper. After that, the main structure components, electrical control system, main functional modules etc. of the system are introduced in detail.Then, an automatic stepping method, which is based on two-layer rail structure, is proposed and deeply analyzed, and the concrete implementation plan of this method is also described; the way to identify current station number and detect docking position during stepping process, which is based on magnetic proximity sensors, is proposed; the harmful impact phenomenon during the process of automatic stepping is analyzed, and the solution to avoid or suppress the influence of this kind of impact is also provided.After that, a base frame calibration method based on visual measurement system is studied. The reason for online measurement using a visual system and the significance of base frame calibration are described at the beginning, and then, by establishing kinematic model and hand-eye relation of the system, a coordinate system of the device from base to camera is set up, which determines the visual measurement principle. With this principle, a base frame calibration method is proposed and analyzed in detail.Finally, the experiments show the reliability of positioning method using magnetic proximity sensors during automatic stepping process; a specific control process for automatic stepping is designed according to the principle, and the feasibility of this stepping method is demonstrated by following experiments; the hand-eye relationship of the system is calibrated and the results of base frame calibration based on visual measurement is also proved reliable and feasible by the experimental results.