| Summary: | 博士 === 國立臺灣科技大學 === 機械工程系 === 89 === Rapid prototyping (abbreviation RP hereafter) is an emerging, non-traditional fabrication method, and has been recognized as a valid tool to shorten the lead-time from design to manufacture effectively. Most of the current RP systems adopt the triangular meshes of STereoLithoraphy (STL) as a standard format for data input. Thus, the construction of triangular meshes directly affects the quality of RP parts and their subsequent processes. Traditionally, STL data are output from 3D CAD models that are built using commercial 3D CAD/CAM software packages. This study, however, differs from the traditional way in that it generates the STL data directly from scanned 3D data points, thus preventing various problems associated with 3D CAD modeling from a large quantity of data points. In order to increase the accuracy and speed of RP fabrication, this research also proposes the methodology to generate multi-nozzle spraying path for RP. Specific tasks involved in this study include:
1. Triangular meshes are formulated directly from the massive data points by an approach of connecting corresponding points between every two adjacent scanning trajectories. For point data measured from traditional CMM (coordinate measuring machine) and possess probe-center data rather than those of the object’s surface data, the triangular meshes can be used to determine the normal vector of each point for probe-radius compensation. Also the triangular meshes are converted into STL data which are ready to use for typical RP machines.
2. The triangular-mesh model is sliced in equal thickness to obtain 2½D contours, a required procedure for RP fabrication.
3. With reference to the available nozzle sizes, each 2½D contour is divided into a number of spraying regions. Spraying paths, including offset path and linear path, are then generated for each region.
To verify the feasibility of the proposed methodology for rapid prototyping through scanned data points, this research develops a Windows-based prototype system using Visual C++ language. A number of practical examples together with their discussions will also be given in this thesis.
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