Study On Blend Feature Recognition And Suppression Method

In the recent years, the CAD model simplification technology has been paid more and more attentions for the requirement of seamless integration of CAD/CAE/CAM. Blend feature recognition and suppression is one important portion of CAD model simplification technology, and is an indispensable step to achieve the seamless integration of CAD/CAE/CAM.In this thesis, new approach to recognize and suppress blend features is proposed. The thesis is organized as follows:Chapter 1 first introduces the main research contents, application areas and current status of the research on CAD model simplification technology and points out main problems in the current CAD model simplification technology research; then presents the specification, taxonomy and recognition methods of freeform features, stressing on the current status of freeform feature research; furthermore, discusses the main research contents, current status and main problems of blend feature recognition and suppression. The chapter ends with the primary research contents and objectives of the thesis.Chapter 2 presents a new method of recognizing blend features. The chapter first introduces the basic concepts related to blend features and the proposed algorithm; then presents in detail the method of recognizing all of blend faces from Boundary Representation of a part, which are further organized as edge-blend feature, vertex-blend feature; lastly depicts the recognition algorithm of blend features.Chapter 3 presents a novel blend feature suppression method that suppresses each recognized blend feature as a whole. The chapter first introduces several topological modification operations and geometric modification operations, which are used respectively to modify the topology and geometry information of the model and canensure the validity of the suppressed model; then presents the algorithm of suppressing the blend feature; furthermore, discusses the method of dealing with degenerate blend face; and ends with some test results at last.Chapter 4 presents an algorithm for recognizing and suppressing the interacting blend face. This chapter first presents the concept of interacting blend face and the related work; then introduces the algorithm of recognizing the interacting blend face using the sharp edges on it; furthermore, gives the suppression algorithm of interacting blend face; and ends with some test results.Chapter 5 introduces the hybrid feature recognition system ZD_AFRS with blend feature recognition and suppression facility. Blend feature recognition and suppression can be used as the preprocessing module of machining feature recognition, and can also run independently to simplify the CAD model. In this chapter, ACIS 3D Toolkit, a commercial geometric modeling engine, is briefly introduced first; then the architecture, key data structure and implementation method of the module of blend feature recognition and suppression are described; finally, some examples of recognizing and suppressing blend features using ZD_AFRS are shown.The final chapter summarizes the main results and makes conclusions of the thesis. Some future research work is also described.