Research And Development Of Virtual Rapid Prototyping System

Rapid Prototyping (RP) refers to a group of techniques used to quickly fabricate a scale model of a part or assembly using three-dimensional computer aided design (CAD) data layer by layer. It can produce any complicated part without need for fixture or mould; therefore, it has become a support technology of the modern advanced manufacturing techniques. However, the spread and development of RP techniques are hindered to some extent by limited function and expensive cost of equipment and low accuracy of prototype part. Among the various influential factors, actually it is most important to choose appropriate process parameters for optimal fabrication of a prototype, which is a trial-and-error basis and is both time-consuming and very costly. Aiming at these problems above, this thesis focuses on the Selective Laser Sintering (SLS) technology, deals with the various key problems during the realization process of virtual rapid prototyping system. The contributions may be summarized as follows:(1) Models a virtual SLS-based prototyping machine according to model AFS-320 by using VRML and EDS UG NX 2.0. In addition, the materials, background and lights are also considered. Based on these above, the control for VRML scene is completed successfully by using VRML Script node and the external authoring interface (EAT).(2) Develops layer file readin, NC file generation, process simulation and part visualization modules by using Java Applet programming, data extracting, processing and transferring is also completed. Moreover, the NC-oriented prototyping simulation process and virtual prototype visualization are implemented.(3) Constructs a process assessment module for virtual rapid prototyping, and presents a new 2D region angle-based method for part volume calculation. The method avoids the disadvantages of bounding box algorithm. The module can evaluate the prototyping process and test the effects of process parameters on the part quality, and is therefore capable of providing reasonable process parameters for users.(4) Implements a Web-based virtual rapid prototyping system - VRPS-I, which has been successfully integrated with RP application system developed by our research group previously. The system resembles the physical fabrication process of prototype part, which facilitates not only visualizing the dynamic process simulation and virtual part prototype but also evaluating the prototyping process. Therefore, it can help predict potential problems prior to the practically physical production, and choose reasonableprocess parameters for users.The work in this thesis not only provides a feasible approach to remote engineering education for rapid prototyping technology, but also helps users choose optimal process parameters, improve part quality and fabrication efficiency, and reduce the cost greatly, which are all beneficial to theoretical studies and engineering applications.