Research On CAD Model Reuse Technologies Supportting Product Rapid Design

With the market demand changing to low-volume and high-variety,the mass customization becomes the trend of production mode gradually.As a kind of product design technology facing mass customization,product rapid design is the kernel technology realizing mass customization.The key factor is the organization,management and reuse of design resource,while enterprises implement the product rapid design.The product meeting the costumer's demand is designed with the optimization and recomposition of design resource, while the product rapid design is implemented.As a kind of important design resource,the number of CAD models increase rapidly with the broadly application of 3D CAD systems.In order to reuse CAD models and serve product rapid design,the reuse of CAD models supporting product rapid design is researched. Some key technologies are researched,such as the product-rapid-design-oriented product family modeling,CAD model retrieval and data exchange between heterogeneous CAD systems.The work of this dissertation is as follows.(1) The reusabilities and reuse levels of CAD model are analyzed according to the characteristics of it.The theoretical system of CAD model reuse technologies supporting product rapid design is built accoding to the reusabilities and reuse levels of CAD model.The constitutions of key technologies in the framework are analyzed.The problems in some key technologies are put forward,and these key technologies include the product-rapid-design-oriented product family modeling,CAD model retrieval,and data exchange between heterogeneous CAD systems.The corresponding solutions are given.(2) In order to develop the rapid design system of the developed product rapidly,the the product-rapid-design-oriented product family structure model is built,and the modeling method are put forward based on modularizing design.The expression of assembly structure based product structure labeled graph is proposed.The module partition method based on frequent subgraph mining is presented,and Apriori algorithm is applied to build the mapping between frequent subgrahs and product family modules.The structural correlation method of product family is presented,which includes the predefinition of the assembly structure of product family,the definition of the configuration relationships among producy family modules and the definition of the parameter correlations among producy family modules.The proposed method is used to build the product family used in the rapid design system of the developed product,which is effective to shorten the developing lifecycle of the system. Moreover,the reuse of CAD model on level of assembly is realized.(3) The CAD model retrieval technology is the powerful tool to reuse the CAD model and improve the design effectiveness.To improve the intelligence and the visualization of the CAD model retrieval tool,the CAD model retrieval method based on topology adjacency approximation is proposed on the basis of boundary matching.The method is divided into two steps.Firstly,Breadth-First-Search-based spanning tree algorithm is applied to obtain an initial boundary matching between retrieval object and retrieval condition.Secondly,the topology adjacency approximation algorithm is put forward to find the optimal boundary matching based on the initial boundary matching by the cycle and approximation process,and the matching result is used to calculate the shape similarity between retrieval object and retrieval condition.Finally a CAD model retrieval system on the UG platform is developed based on the proposed method.Experimental results show that the retrieval precision and effectness of the proposed method is higher than other methods,and the adaptiveness and the practicability is better.(4) Aiming at solving the problem on the reuse of heterogeneous CAD model during the process of product rapid design using CAD system,the method of integration data exchange among heterogeneous CAD systems is proposed.The framework of the method is built,and the implementation mechanism is analyzed.The information constitution of CAD model on level of feature is analyzed.The description method of feature information based on feature class is proposed,in which the geometry element identifaction method based on improved geometry certification is presented to name and identify geometry element.The transformation method of design intent information is given,and the design intent information includes design history,feature and constraint.The proposed method has been used in the data exchange between CATIA and UG.Experiments results shows that the sharing, exchange and reuse of CAD model among heterogeneous CAD system can be realized,the loss of design intent is less than other methods,the variant results of target CAD model is same as the source CAD model.(5) The framework of product rapid design system based on the reuse of CAD model is built according to the above-mentioned methodologies,and the function modules of the system are planned.The horizontal condenser is taken as the example to validate the key technologies above-mentioned such as the product rapid design based on product family,the retrieval and reuse of CAD models,the transformation and reuse of heterogeneous CAD model,and the the management and resuse of standard parts model.A rapid design system has been developed for a refrigeration enterprise,and economic benefit was gotten. Finally the research work of this dissertation is summarized,and the innovations are pointed out.Moreover,suggestions for further study are put forward accordingly.