The Research On STEP-NC/Web-based NC Milling Machining Simulation

Numerical control (NC) machining simulation means that by using the computer modeling and graphic simulation technology, NC machining process is simulated in the computer. That is to say, without the comsumption of actual materials and the occupation of actual machine tools, not only the kinematic simulation of machine tools, the simulation of material removal from the workpiece and collision checks among machine tools, fixture, cutting tools and workpiece, etc. can be done, but also the rationality of the workpiece loading, the feasibility of the selected machining parameters and the machinablity of the workpiece can be evaluated. Therefore, NC machining simulation not only can be considered as the most economical and effective verification method, but also makes the cost reduced, the development cycle of the product shortened, and the quality of the product and the training for operators improved. In addition, with the development of advanced manufacuturing technology and Internet technology, it has become an important part in virtual manufacturing and a basis to realize the networked manufacturing.So far, most of research or commercial software about NC machining simulation undergoes such issues that they are based on G&M codes, dependent on specific platform, stand-alone and with poor interoperability etc. Therefore, these simulation systems are not adaptable to the development of modern manufacturing. In this context, based on a comprehensive analysis of the domestic and overseas NC machining simulation research, the dissertation considering the NC milling machining as the research object proposed the architecture of the STEP-NC/Web-based NC milling machining simulation system and elaborately studied its key technologies, surrounded by the new NC data standard STEP-NC (STEP-compliant Numerical Control, STEP-NC) proposed by International Organization for Standardization ISO (International Organization for Standardization, ISO) and developed a prototype system. The main contents are as follows: (1) The dissertation provides a comprehensive survey about the domestic and overseas NC machining simulation research and analyzes existing problems. On this basis, the dissertation presents its research direction and ideas.(2) It describes the development process, structure and contents of the STEP (STandard for the Exchange of Product data, STEP). Further, as an extension of STEP for CNC (Computer Numerical Control, CNC), the background and development of STEP-NC are discussed. And the focuses of the domestic and overseas research on the STEP-NC are summarized. Also, the data model of STEP-NC is studied. In addition, comparing the two standards of STEP-NC:ISO14649and ISO10303-238, the ISO14649is selected as the research standard of this dissertation. Moreover, with the comparison of the traditional NC standard ISO6983and STEP-NC, the advantanges of STEP-NC are elaborated.(3) Facing the issues from current simulation systems, the functional model of the STEP-NC-based NC milling machining simulation system and the architecture of the STEP-NC/Web-based NC milling simulation system are proposed. Moreover, the key technologies to realize the STEP-NC/Web-based NC milling simulation system such as the development of Web-based application system, the generation of STEP-NC milling program, the information extraction from STEP-NC milling program, process planning and optimization, the generation of tool path, solid modelling based on the feature, kinematic modeling technology, graphics dynamic display technology and the modeling of physics model to realize the STEP-NC/Web-based NC milling machining simulation system are given.(4) The development of Web-based application system is studied. That is, the work structure and development language of Web-based application system, the development technology on the client and server side, the integration technology of heterogeneous environment, data transmission formats, servers, and the Web-based product data management system to meet the distributed and heterogeneous manufacturing environment are intensively studied.(5) According to the system’s functional model, the generation of STEP-NC milling program as data preparation of NC machining simulation which is involved in the STEP203CAD file-based feature recognization, STEP-NC manufacturing feature-based macro process planning, detailed process planning and micro process planning as well as the mapping into the STEP-NC physical file is first studied. Then, to obtain reasonable tool-path, the optimization of STEP-NC-based milling machining process planning, especially the multi-objective optimization of milling cutting parameters in a single workingstep, and the planning methods of STEP-NC milling feature-based tool-path are presented. In the following, the establishment of a virtual machining environment is studied. I.e., the method taking manufacturing features in the workingstep as the basic unit of geometric modeling of stock model and workpiece model is proposed; the geometric modeling method of ISO14649-111milling cutting tools is given, and the data model of STEP-NC compliant NC macine tools is built.(6) To meet the integrated, flexible and intelligent development of of process planning, the combination of genetic algorithm with neural network expert system is used to the STEP-NC-based process planning and a STEP-NC-based intelligent process planning platform is proposed and established.(7) The prototype system of STEP-NC/Web-based NC milling machining simulation is developed, which verifies the reseach of the dissertation.