Research On Key Technologies Of Process MBD Model Generation In Three-dimensional Machining Process Design

The traditional 2D process planning has been unable to adapt to the development of digital technology due to low automation level,poor data flow and weak visibility.Therefore,a new mode of 3D digital process design based on MBD technology for the manufacturing characteristics of machining parts is explored in this paper.The process MBD model is defined as the final output process reference file of the 3D process design.And the key technologies such as the definition of process MBD model,manufacturing feature recognition and information extraction,process MBD model generation and release are studied,which lays a foundation for CAD/CAPP/CAM system integration.The specific content of this paper includes the following four points:(1)Research on the definition,expression and storage of process MBD model.Firstly,the relevant definitions of the process MBD model are studied,and a process reference document with better readability and information expression ability is determined.And the information annotation expression method of process MBD model based on MBD 3D annotation standard is proposed.Then the visualization and nonvisualization storage methods of process MBD model are studied.Finally,the overall process of generating process MBD model for machining parts is summarized,and the key technologies studied in this paper are identified,which are manufacturing feature recognition and information extraction,process MBD model generation and release technology.(2)Research on manufacturing feature recognition and information extraction technology.Firstly,the manufacturing features are defined and classified.And the geometric/topological information of the design MBD model for part is extracted.Secondly,the method based on graph matching is extended to construct extended attributed adjacency graph,and the feature matching method of graph isomorphic based on matrix mapping is proposed to realize the fast and accurate identification of the manufacturing features of machining parts.Finally,the feature information extraction technology based on NX/Open secondary development tool is studied to provide the data source of part feature information for process planning.(3)Research on generation and release technology of process MBD model.Firstly,the step geometry model is defined as the information carrier of process MBD model,and the method of reverse creation and modification of step geometry model based on feature mapping is studied.Secondly,the annotation expression method of process information in the form of process information frame is studied to realize the comprehensive,clear and standardized expression of process information.Finally,the process MBD model is organized in the form of model tree,and the lightweight process MBD model is used as process reference document to realize the publication and transmission of process information.(4)Feasibility and accuracy verification of key technologies for MBD model generation.A rapid process MBD model generation system is developed by C++ programming language and NX/Open secondary development tools based on NX10.0 software platform.Finally,taking differential case as an example,the systematic results and theoretical results of rapid generation for process MBD model are compared and analyzed,which verifies the feasibility and accuracy of the key technologies of process MBD model generation.In summary,the key technologies of process MBD model generation in 3D process planning are studied,which changes the traditional process design mode mainly based on 2D process drawings,provides a reference for the new 3D digital process planning mode,and lays the foundation for the integration of CAD/CAPP/CAM systems.