Research And Implementation Of CAB Model Verfication System

In the Concurrent Engineering and Collaborative Design environment, CAD model, as the carrier of the design and manufacturing data of products and the connection of transferring information among different individuals, exists in multiple design and manufacturing processes including product design, engineering analysis, process planning, CNC programming, tooling design and so on. Defects of CAD model in quality may lead to adverse effects on many aspects such as fulfilling of products’ functions, data exchange, management and reuse of products’ data. However, there has been no effective verification mechanism to ensure the quality of CAD model. Therefore, a system to verify CAD model is investigated and developed in the present paper, which could reduce the defects of the model, benefit the management and reuse of products’ data and as well shorten product R&D period and increase enterprises’ profits.Firstly, the quality of CAD model is studied. The main quality defects and the main causes of the quality defects are analyzed. Besides, Scheme design of model verification system is proposed on the basis of the above research.Secondly, some key techniques which are related to this system are studied. Object-oriented technology is used to analyse the CAD models and inspection rules, and the model of checking rules customization is established on the base of UML, Information constitution of CAD model is researched; Moreover, Pro/Toolkit-based technique to extract model information and STL-based technique to read model3D-data are studied as well. Feature quality defects detection algorithm is studied.Thickness detection algorithm based on the octree algorithm and the ray tracing algorithm is presented, which is characterized as quick-speed and convenient for designers to rapidly locate design defects. A standard-referenced statistical algorithm is proposed which is beneficial to enterprises’standardization. By investigating the factors affecting the model’s quality, the CAD model quality evaluation indicators system is introduced. Analytic Hierarchy Process method are introduced to calculate the weights and values of evaluation indexes respectively, evaluation index values are attained based on the model’s checking results, and the final evaluation value, combined with the weights and values of evaluation indexes, is acquired as evaluation reference of the CAD model. Technique to display inspection results and inspection results statistical analysis technology based on EXCEL are studied.Finally, the interface of each function module of the system is designed, and the system is developed by use of tools such as Pro/Toolkit in VS2005environment based on the foregoing investigation. Besides, each functional module is realized completely, and the system is validated and evaluated according to the implementation in enterprises.