Research On Part Information Modeling And Process Planning In 3D Environment

As a bridge connecting the product design system with the production management system, CAPP system plays a key role in informationization of the manufacturing enterprise. Developing a CAPP system based on the platform of 3D-CAD, which is helpful to utilize 3D design features, is one of the up to date trends and research hot spots in CAPP technologies. In this thesis supported by an 863 program, two important technologies of the CAPP in 3D environment consisting of the part information modeling and the process planning are studied.After the review of the current situation and the trends of CAPP system, the basic characteristics, advantages and the potential significance of CAPP in 3D environment are analyzed. The framework of such a CAPP system is also constructed.The technologies of part modeling and information storing for process planning in the 3D environment are presented, in which the process information and the geometric information are linked together by adding the non-geometric features to the 3D entities. The extended entity relationship (EER) conceptual model translated from the feature model is applied to express these relationships among the part features. The translation rules from the EER model to the entity relationship (ER) model are established. Database tables are designed in detail to store these part feature information.Furthermore, the case&rule-based process planning in the 3D environment is put out. The most similar part is selected according to the comparability calculation of the 3D features. The process route of this case part is taken as the base information in process planning of the new part whose final process route will be determined after some adjustments according to the predefined rules.To validate the methods and technologies discussed above, sCAPP, a prototype system on the basis of SolidWorks, is developed. Some practical examples are then given to illustrate the functions of the system.Finally, the work of this thesis is summarized and the further research orientations are pointed out.