| CNC milling finishing process planning for complex surfaces is an important part of the entire CNC machining process.Due to the flexible diversity of the shape of complex surfaces,the traditional finishing CNC programming method requires analysis of the 3D modeling and machining manufacturing semantics of complex surfaces to determine the appropriate milling method,drive method,tool and other machining strategies,as well as the selection and setting of machining parameters.This process suffers from low programming efficiency,human judgment errors,and conservative selection of machining parameters.To avoid the above,this paper develops a prototype system for automatic generation of CNC milling finishing process planning for complex surfaces,using the CNC milling method in NX software as the research object.The main research contents of this paper are as follows:(1)Framework design of the prototype system.The machining process planning flow corresponding to the milling method often used for finishing complex surfaces in NX CAM system is analyzed,the main functions of the prototype system are determined,including the automatic decision-making function for machining strategies and the planning and recommendation function for CNC machining parameters,and the framework of the overall structure is designed using the modular design principle.(2)A study of the correlation between surface features and machining strategies.Combining the definition of CNC machining planning operations in the NX CAM system and CNC machining theory,machining features are defined as unique objects with geometric features and machining information in complex surfaces and associated with specific milling methods,drive methods,and tool geometry parameters.An automatic decision module for machining strategies based on NX secondary development is established,and machining features of surfaces to be machined are automatically identified to obtain surface feature information.(3)A study of algorithms for planning and recommendation of CNC machining parameters.A graph-theoretic modeling of the machining parameters of milling methods in NX CAM system is used in a layer-by-layer order,and the factors affecting the selection of machining parameters are analyzed,which include conditional factors and instance association factors.The surface feature information and machining manufacturing semantic information of complex surfaces are used to express the condition factors,and the Page Rank algorithm is improved based on the graph theoretic model of complex surface instance library,which is used to determine the instance association factors.A multi-attribute decision method based on information entropy is used to obtain the combined influence factors of the two factors,and then the optimal machining parameters in each layer are decided.A CNC machining parameter planning and recommendation module based on the Neo4 j graph database development is established to realize the CNC machining parameter planning of the surface to be machined and the recommendation of related parameter values,so as to obtain the optimal machining parameter information.(4)Implementation of the prototype system.Using the convenient storage and reading characteristics of CSV files,information interaction between the NX secondary development module and the Neo4 j graph database development module is carried out to achieve automatic generation of CNC milling finishing process planning for complex surfaces.(5)The prototype system is used to perform the verification of the example.The original finishing process planning of the example and the finishing process planning generated by the prototype system are compared and analyzed,including toolpath trajectory and surface quality,to verify the feasibility and effectiveness of the prototype system.The prototype system effectively solves the process planning problem of complex surfaces in the process of finishing CNC programming,and improves the quality of CNC machining process planning and the efficiency of CNC programming. |
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