Multi-level numerical control program structure for aircraft wing flexible drilling

To realize automatic flexible drilling for aircraft wing, according to characteristics of wing structure and assembly, flexible drilling technology for aircraft wing was studied and a new secondary location method for flexible drilling process was proposed. Based on this technology, the multi-layer numerical control program structure was classified into three layers, which included overall structure layer, single rib processing layer, and the single hole processing layer. In the overall structure layer, general structure of numerical control program was depicted, and it was composed of setup of basic units in process and drilling sequence of each single rib. The single rib processing layer was used to plan not only the machining process of rib processing but also the tool path. The single hole processing layer completed the basic link of flexible hole drilling process by subcycle. An off-line programming system oriented to flexible wing drilling was developed to quickly generate the numerical control program structure. The programming efficiency and the maintenability of the program were analyzed by comparison to traditional programming methods. Effectiveness of the system was proved by applying in an aircraft wing assembly.