NC Programming Technology Research Of Aircraft Structural Parts Based On Model Definition And Classification Coding

The aircraft structural parts are important parts which constitutes the aircraft frame and aerodynamic shape. They have different types and important functions, so it is important to improve their NC machining efficiency and machining quality. The level of automatic NC programming for aircraft structure parts is improved by the features coding technique and model based on the definition technique. This paper mainly does researches on the following aspects:1. The aircraft structural parts MBD model is build based on CATIA V5. The model includes design information and process information. Machining process model of aircraft structural generation process is put forward based on the aircraft structural MBD model.2. The aircraft structural parts feature recognition based on the graph is put forward.Features recognition is important for parts machining process routes decision-making and NC programming. Getting the aircraft structural parts attribute adjacency graph first;removing all convex edge points in the attribute adjacency graph in order to achieve the concave adjacency graph. Then removing the surface of the blank points in the adjacency graph in order to achieve the sub-graph of parts processing characteristics;matching manufacturing features sub-graph with predefined graph to accomplish the feature recognition of the aircraft structural parts.3. The aircraft structural parts machining feature is decomposed into independent manufacturing units. The frame of the manufacturing units coding system is presented.Manufacturing units are coded in classifications and their group processes are planned.The significance of manufacturing units codes are expounded in the design and production of aircraft structural parts. The manufacturing unit information template is build. The sorting method and the purpose of processing units are focused on. The manufacturing processes of aircraft structural parts were analyzed from the aircraft structural manufacturing materials, manufacturing methods, manufacturing parameters,machine tools and fixtures and cutting tools. The aircraft structural parts process decisions are made through their non-geometry information. The based-on-code NC machining processes of aircraft structural parts are put forward.4. Combining with MBD technology and Group Technology, A NC machining system of aircraft structural parts is developed by application of CAA secondary development platform based on CATIA V5. The system consists of feature recognition module, the CAPP process decision module and NC programming module. It can effectively realize the aircraft structural parts technology information extraction,improve the ability of the aircraft structural parts process decision to a certain extent and realize the automation of the aircraft structural parts NC machining.