| With the growing fierce competition in the global vehicle industry, the development of China’s vehicle industry is confronting with serious challenges. As one of the most important part of auto body,automobile panel is one of the determinants in the case of car overall performance and modeling. The core competitiveness of a car can be enhanced by high-quality automobile panel. Along with the popularity of CAD technology, a larger number of data standards as well as better standards, quality standard for three-dimensional geometric modeling of automobile panel has been upgraded. In order to realize the design purpose for automobile panel, to ensure the quality of curve reconstruction, and guarantee the successful implement in downstream simulation analysis and process planning, this paper will put forward the concept of high-quality curve reconstruction in automobile panel. In addition, a deep study of the methods on improving its quality would be made.1. Based on Bezier, B-spline, and NURBS curve reconstruction theory, this paper will deploy CAD technology and computer graphics and other interdisciplinary theories to construct a digital model of the roof space, and to analyze its dimensional accuracy and fairness. On the premise of dimensional accuracy of curve reconstruction, using BEZIER theory in making curve reconstruction can give automobile panel the best fairness, and can guarantee the quality of curve reconstruction.2. After delving into surface orders, control point numbers and other relevant mathematic theories, this paper works out that surface orders, control point numbers can improve the accuracy of curve reconstruction, at the same time, they can also bring low operation efficiency and poor fairing. In order to coordinate the accuracy of curve reconstruction, fairness and operation efficiency, this paper will make three-dimensional geometric modeling for the proof of cars, and will carry out analysis under various surface orders and control point numbers. This paper will put forward that surface orders should be less than nine, control point numbers should be kept between sixty to eighty, which is most suitable for automobile panel. What’s more, within the above scope, balance is achieved among the accuracy of curve reconstruction, fairness and operation time.3. This paper will put forward a precise point cloud data block approach to settle the low accuracy problem. Based on analyzing differential geometric characteristics of curved surface boundary area, this approach makes use of the curvature extreme method to extract the feature point. By Gauss curvature method and the average curvature method, automobile panel point cloud is labeled as eight types of curved surface. And this paper will complete the precise point cloud data block, with regional generation method based on feature points constraint. This paper will apply the above data block approach and the traditional data block approach which is based on the edge respectively into the curve reconstruction of car doors, and make a comparison between them in terms of the quality of curve reconstruction. The above efforts can prove that the quality of curved surface can be improved.4. For this paper regards class A curved surface as its standard for developing accurate curve reconstruction of bonnets, it will apply precise block technology, increasing the order number, method of adjusting control point into curve reconstruction of bonnets, so as to achieve high-quality curve reconstruction in automobile panel. This paper will make use of the reverse surface reconstruction software Icem Surf of Bezier theory to finish the three-dimensional modeling for curved surface of bonnet, and tests will be carried out in terms of accuracy, fairness, curvature change, and surface gap. The reconstructed bonnet is able to reach class A standard, and a balance can be reached between accuracy of reconstructed surface and fairness, therefore, the proposed method on improving the quality of curved surface is effective. |
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