注射模设计的三维模型英文文献和翻译(6)
I. 3D Modelling and Assembly.
A mould base is essentially an assembly of many components such as plates, bushes, pins,and screws. To facilitate mould base design, the designer must be provided with a library of ready-made mould base components. By selecting a particular dimension, a standard mould base will be generated. To facilitate these, a library of 3D-based functions, corresponding to the requirements mentioned in Section 6.1.2, are identified and developed. As the codes are object-oriented, they can easily be expanded to accommodate other mould design modules when required.
II. 3D Visualisation.
Using the functions provided in the graphical output, together with OpenGL as the graphical interface, several functions are developed for 3D rendering, view projections and view transformations. These include:
1. Rendering 3D parts with selected colours (Fig. 6).
2. Rendering 3D assemblies with selected colours (Figs 7 and 8 for rendering in shaded and wireframe modes, respectively).
3. Rendering other 3D entities on screen with selected colours.
4. Rendering inpidual components with a different colour in a mould base assembly.
5. Interactive view transformation such as rotation, translation,and zoom.
6. Assembly tree display and manipulation.
III. 3D Data Management. Portability is one of the benefits of developing a stand-alone application. It is thus important to adopt an open format for maximum portability. The native Parasolid file format (.xmtFtxt) is thus used instead of a new file format. Data management requirements of a mould base module include the following:
1. Open, Save, Save As and Close Parasolid part files.
2. Open, Save, Save As and Close Parasolid assembly files.
3. Import and Export part files.
6.1.3 Mould Base Modules (C)
In order to facilitate the automatic generation of standard mould base assemblies, the application must provide a library of mould base components, whose dimensions depend on standard values found in catalogues. To facilitate design, subsequent modifications to these dimensions have been enabled.The details of this module will be discussed in Section 6.2.
6.1.4 Database Support (D)
A standard mould base requires almost a hundred parameters to completely represent the dimensions and positions of the inpidual components. Many of these parameters are inter-related and can be derived from others. A database file is thus required to store the catalogue-based parameters of standard mould bases. Microsoft Access database format is used, as there are facilities in the MFC for direct access to Access Database files. Using the Data Access Objects (DAO) in the MFC, a set of functions is developed for the extraction and management of these relevant parameters from the database.460 T. L. Neo and K. S. Lee Fig. 9. Sample code for the mould base designer.
6.2 Development of the Mould Base Design Module The mould base module consists of three major sections,namely, the mould base component library generator, the mould base assembly generator, and the mould base selection and customisation module. A fourth section, called the mould base parameters manager, is also developed to provide database support for the application. These are illustrated in Fig. 5. The3D Kernel Development for Injection Mould Design 461 details of each section are discussed in the following.
I. Component Library Generator.
With support from the 3D developer layer, standard components for mould bases are created and stored in the component library. By specifying the appropriate dimensions, these components can be generated and used by the mould base assembly generator when required.Figure 6 illustrates a cavity plate created by the components library generator.
II. Assembly Generator.
Using the 3D developer layer and the component library generator, standard mould bases are assembled and stored in the assembly library. When supplied with a particular parameter set from the database support,specific standard mould base assembly can be automatically generated. Figure 7 shows a “HOPPT” two-plate mould base created by the assembly generator.
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