Research On Dynamic Creation Method Of Process Model Based On Evolutionary Machining Features

In recent years,with the continuous development and application of MBD technology,3D process model has gradually replaced 2D process drawing and become the only basis to guide product processing and manufacturing.However,the existing 3D process model is mainly a static process model,which can only describe the processing state of parts before and after the completion of the process in a discrete way,ignoring the continuity and time variability of the evolution of parts in the cutting process,and cannot support the visual expression of the dynamic evolution of parts,which has become the bottleneck of the promotion and application of intelligent product process design.Therefore,based on the three dimensions of process semantics,processing time and processing characteristics,this thesis comprehensively analyzed the dynamic evolution process of parts,focused on overcoming the technical difficulties such as the topological and geometric evolution expression of processing features,the coupling mechanism of process parameters and evolutionary processing features,and the rapid construction of removal volume model,and proposed the dynamic creation method of three-dimensional process model.The main research contents are as follows:(1)Describes the overall scheme of dynamic creation of process model based on evolutionary processing characteristicsFirstly,the related concepts of evolutionary machining features were defined,and the geometric evolution process of parts was described based on the time dimension,and then the dynamic characteristics of evolutionary machining features were expounded.Secondly,the limitations of the static process model in the application process were analyzed.At the same time,according to the requirements of visual expression of the dynamic evolution process of parts,the dynamic creation framework of the three-dimensional process model was constructed,and the corresponding technical route was formulated.(2)Proposes a multi-dimensional driven representation of evolving processing featuresFirstly,on the basis of process semantic analysis,the mapping relationship between process information and evolutionary processing features was discussed,and the process information model of evolutionary processing features was constructed.Secondly,the spatial position constraint relationship between the feature surface groups was analyzed and defined,and then the attribute adjacency matrix was constructed to express the topological evolution of the feature.Finally,the cutting state evolution process of milling and drilling was analyzed,and the machining process was divided into different stages according to the evolution law of the removal geometry.Through geometric reasoning method,the correlation relationship between machining time and geometric parameters of evolving machining features was established,and the mathematical representation model of evolving machining features was constructed to realize the geometric evolution representation of machining features.(3)A dynamic process model creation method driven by process data was proposedFirstly,by analyzing the process semantics of typical program instructions in NC code,the coupling mechanism of "NC code,process parameter and evolving machining characteristics" was constructed.Secondly,the correlation between the process parameters and the machining section is discussed,and the corresponding machining section is generated according to the spatial position relationship between the tool and the machining characteristic surface.Then,by establishing the mapping mechanism between the machining section and the removal body,the relevant process data was extracted from the NC code based on the process semantics,and the parametric construction of the removal body model was realized.Finally,according to the geometric relation between the removal volume model and the process model,the dynamic construction of the process model is realized by using Boolean operation.(4)A dynamic process model creation module is developed and applied for verificationAccording to the method proposed in this thesis,in the 3D process design prototype system,the corresponding function modules of rapid construction of volume removal model and dynamic creation of process model are further developed.The effectiveness of dynamic process model creation method in this thesis is verified by running the demonstration function module in different cases.