Study On Hollowing STL Model And Shape Follow-up Technology In Rapid Prototyping

On rapid prototyping (RP), building a hollowed prototype instead of a solid part could reduce the building time and the material consumption. When manufacture the LOM prototyping part, using shape following technology can not only reduce the time on making grids of slices, but also save on silicon rubber in manufacturing silicon rubber modules. This paper researches the algorithm about the hollowing STL model, discusses the means of shape follow-up and implements the shape follow-up in interactive CAD.After analyses the base process of RP, research characters of STL file and description means of 3D geometry and research many previous means of build hollowing part in RP and their shortcoming, finally presents a simple algorithm for hollowing out STL model. The algorithm employs voxel representation to do the hollowing, which use close array cube (voxel) to describe STL model. Hollowing model can get by deleting external voxel of STL model. The hollowing model created by the algorithm is constant wall thickness and no collision.In making silicon rubber modules of irregular part by using LOM technology, always great lot of silicon rubber are consumed and lots of time are spent on making grid. This paper present shape follow-up technology that adds outline border in irregular STL file and filled entities in holes. Analyses disadvantages that offset 2D sliced contours of STL models to add entity. This paper offers means, which use interactive CAD to add entities. Make certain the rule of added entity through experimentation and present corresponding resolution. Finally, Using the mouse message mechanism of Windows system, the Document/View structure of MFC and the feature of OpenGL, this article realized the adding outline border and adding filled entities in irregular STL in holes.