Research On Virtual Assembly Process Knowledge Management Of Shafting And Propeller

Virtual assembly process design is a bridge connecting 3-D model and virtual visualization,and is also an important part in digital assembly system.Compared with the traditional mode,it puts the process information base into the virtual assembly environment,and combines the assembly model to guide and present the process knowledge.In this way,it is not only convenient for technicians to guide and modify process information,but also enables assemblers to use visual presentation to improve their awareness of the assembly process.In recent years,although virtual assembly design has developed well,there are still some difficulties on research.Firstly,it is difficult to present the input and output of process information in a virtual environment,so it is difficult to present the corresponding models in a proper way.Secondly,there are some challenges in visual simulation under the design of virtual environment.The reason is that the simulation involves many links and contains assembly process elements,which makes the simulation workload huge and requires high requirements for corresponding process designers.Therefore,how to standardize the assembly process information and provide a more convenient information import method has become the most urgent problem to be solved.In order to solve the above problems,this paper takes the virtual assembly of shaft propeller as the object,and studies the visual presentation of assembly process knowledge.The main research contents of this paper are as follows:1)Ontology modeling of shaft propeller assembly process.Firstly,according to the assembly requirements,the composition of assembly process information is proposed and it is decomposed and defined.Secondly,the concept of assembly process information is built and defined by ontology,the relationship definition of assembly object,assembly process and assembly resources is given,and the ontology process information integration framework is proposed.Finally,the propeller assembly ontology model is verified by an example.2)Research on assembly process sentences.First of all,the part of speech and grammar of process sentences are analyzed,and the basic elements and related methods of sentences are put forward.Then,the text information in the original data is extracted by process information mining,and the text detection and recognition methods are described.Besides,the TF-IDF method is used to match the keyword similarity for the extracted information elements,Levenshtein algorithm is used to calculate the similarity of process information,and the matching result is associated to the information model.Finally,the process statement splitting and information matching calculation are analyzed with examples.3)Design of knowledge base for 3-D assembly process of shaft propeller.First of all,the structure,tooling and process information in shaft propeller assembly are described.The description includes hierarchical division,key information,process elements,etc.,and the structure building,tooling and process information base is established.Then,the requirement analysis of virtual assembly is carried out,and according to the analysis results,the virtual assembly process design flow is proposed.Finally,the construction and simulation of the 3-D model are described.4)Design and implementation of knowledge system for virtual assembly of shaft propeller.Firstly,the overall design of the system is proposed,including architecture design,functional structure design,development environment introduction and system tools introduction.After that,the implementation method of some functions is verified by an example,and the verification content includes building the process information base of the shaft propeller body and realizing the database to the virtual assembly platform.