Research On Digitized Design Of Engineering Drawings Based On Solid Model

3D-CAD technique is a hotspot of CAD research and application, and digitized design of engineering drawings based on solid model is an important subject of this technique.Three-dimensional design is an inexorable trend of CAD application. However, while the design is beginning from 3D, the engineering drawings created by three-dimensional model are still needed for manufacturing in current situation. Therefore, it is significant for studying engineering drawings correlatively created by solid model.Engineering drawings is a kind of graphic representation of engineering design and product information, which is used for representing design ideas, preparing materials, controlling manufacturing and measuring process, and it has been a kind of communication tools as a common design language for technicians and engineers to convey information.With the application of CAD technique, both the design apartments and the factories have realized the digitized design of engineering drawings, which enables both the process of drafting and exporting drawings more scientific, standardized and automated. Using 3D-CAD technique, designers have gotten to use more advanced parametric three-dimensional systems, such as CATIA, UG, and Pro/E, for their engineering designs. At the same time, it is possible to create engineering drawings by the solid model correlatively and to reuse the information of three-dimensional solid model in two-dimensional engineering drawings. However, there are a lot of problems in two-dimensional representations of the engineering drawings in this method. To solve the problems, designers are always needed for revising, treating in coincidence with the traditional conventions for drawings.The main work in this dissertation is beginning from the application of 3D-CAD and the digitized design of engineering drawings based on solid model. From the initial research for creating the orthographic digital model of the objects by the virtual environment of 3D-CAD system, to the establishment of reusable standard drawings through data exchange by means of parametrical technology, and to the research on two-dimensional representations of engineering drawings by the solid model in detail, including to create all kinds of views, sectional views, revolved and removed sections, and other conventional representations. Many kinds of the problems in two-dimensional representations of engineering drawings are discussed correspondingly and some solutions relatively with the problems are presented. It is useful for the standardization and normal representation of engineering drawings.First, a method to establish the digital model of object's orthographic projection is presented. The digital model has some advantages compared with the traditional graph model: the object's virtual projection is not the contour's figure simply, rather than including both the projection and the shadow of the object, and the visible edges show thick continuous lines and the invisible edges show thin hidden lines. This virtual projection system model can display directly the process of getting the object's multi-view projections.Then a method to create the standard drawings that accord with GB in CATIA V5 by sharing data of AutoCAD templates is presented. At the beginning, we import the templates in DXF/DWG format of AutoCAD that accord with GB into CATIA V5, and share the data in CATIA V5. However, the frame and title block in the template drawings cannot be reused by other drawing documents. Therefore, we study on how to transform the imported figures into background views in detail, and enable them become the real background views in CATIA V5, and then implement the method to create a series of reusable standard drawings by means of parametrical technology eventually. This method has the characteristics of simplicity, usefulness, and efficiency, and has some practicable value for improving both the standardization of engineering drawings and the efficiency of drafting processing.Finally, It has been discussed systematically that the two-dimensional representations of engineering drawings based on the solid model, including create all kinds of views, sectional views, revolved and removed sections, and other special representations. An advanced drafting method is provided for users to create two-dimensional engineering drawings by the generative drafting that generates drawings from three-dimensional solid model. Creating all kinds of representations that accord with GB in CATIA V5, some representations can be generated by the system tools directly, and some have to be got by means of the method in this paper. In a word, all kinds of representations that accord with GB are implemented in CATIA V5 through our research. However, some two-dimensional representations created by the generative drafting method based on solid model do not accord with GB conventions. We have analyzed many kinds of the problems in two-dimensional representations of engineering drawings using the generative drafting in detail and have presented some solutions relatively with the problems. As a result, design reuse is implemented by means of the correlativity between the two-dimensional engineering drawings and the three-dimensional solid models, and design efficiency is improved, which has some reference value for drafting the engineering drawings. It is helpful and useful for both apply abroad advanced CAD systems in our country and normal representations of engineering drawings domestically.In conclusion, useful methods and approaches for the research and development of digitized design of engineering drawings based on solid model are provided in this dissertation. The achievement of the investigation has enriched the CAD applications in digitized design of engineering drawings, solved a lot of real problems in practice, and had some theoretical and practical value.