Research On Rapid Prototyping Slicing Method Based On STL Model

Rapid prototyping technology is different from the traditional reduced material processing mode,it sliced the 3d model into a series of 2d layers,compared with the traditional processing method saves time and cost.The core of the rapid prototyping technology is the slicing.The result of the slicing determines the final efficiency and precision.In this topic,slicing of the STL model is studied,and developing a slicing application “STLSlicing” based on SDI and OpenGL.The ASCII STL model is the interface document of the application.The software realizes the functions of 3D visualization of STL model,uniform thickness slicing and adaptive slicing.In the 3D visualization of STL model,three dynamic link libraries of OpenGL are introduced.Among them,the GeoKernel.dll is the core,it defines the STL model of geometric objects(triangular patches,a single entity,etc.);The glContext.dll achieve the model display material,light source and transform operation;The GepmCalc.dll is the foundation of the other two libraries,it provides the basic geometric object class and the calculation function geometric relationship.Through the above three dynamic link library to build a hierarchical structure to achieve the visualization of the STL model.In the uniform thickness slicing algorithm of STL model,search intersection triangles,gradually remove those have been involved in triangle intersection,gradually reduce the traverse range,reduce the number of triangles by repeated search.Establishing free triangle table to store intersecting triangles,dynamic topology based on the free triangle table is constructed,and the dynamic topology based on free triangle table is established makes full use of the high repetition rate between adjacent layers of the STL model,can quickly generate closed contour.Adaptive slicing algorithm,according to the specifications of nozzle molding equipment in FDM process and supplies used in the thermal expansion coefficient of the projections of the slicing thickness of the maximum and minimum values,to determine the range of adaptive slicing thickness.On the choice of the adaptive slicing thickness value,by calculating the difference of the length difference between adjacent layers and the deviation of the center of gravity offset distance and the set threshold,the slicing thickness of the adaptive layer is constrained.The slicing algorithm proposed in this paper has been implemented on the application “STLSlicing”,and the result of the slicing effect is consistent with the theoretical analysis.Through this research,improve the efficiency of uniform thickness slicing algorithm;adaptive slicing algorithm,slicing precision and efficiency in ascension is also guaranteed,thus providing the possibility for the application,the next step with the rapid prototyping equipment.