| Rapid prototyping technology's principle is to slice the 3D model data into twodimensional plane layer,and then make the manufacturing layer by layer.Slicing is one of the important steps in rapid prototyping.At present,the widely used slicing algorithm is equal thickness slicing,which is simple in principle,easy to implement and fast in program execution.However,in order to improve the accuracy of slicing,it is not limited to the thickness of the layer.Adaptive means to use different layer thickness in the same model,use thin layer thickness in the place where the requirements are more precise,and use thicker layer in the rest of the part.Adaptive thickness stratification can reduce the error caused by step effect without sacrificing mass production time.But even if the minimum layer thickness is used,the step effect cannot be avoided in the plane layer structure,and the mechanical strength reduction caused by the discontinuity between layers is also cannot be avoided.After a lot of literature research,based on the existed STL slicing algorithm,this paper studies the accuracy,efficiency and strength problems of the molding process,and has made some progress.A fast external adaptive and curved-layer hybrid slicing method is proposed.Fast external adaptation: fast external adaptation uses the basic layer thickness to extract the initial layer contour,and extracts the worst angle of the layer.Through the worst angle finite subdivision algorithm,the residual height is used as the criterion,and the final layer thickness is determined according to the calculated subdivision times.Finally,the model is divided into internal and external parts by using polygon Boolean operation to realize the model The overall adaptability.Its feature is that the adaptive layer thickness only acts on the outer shell part of the model,and does not modify the inner part and support of the model.Curved-layer hybrid slicing: most rapid prototyping systems rely on a series of two-dimensional layers,which leads to the inevitable step effect on the surface of parts.According to the angle of the patch,we extract the patch which is suitable for hierarchical processing,and propose the neighborhood normal to mean method to offset the surface with high precision,generate the printing track in three-dimensional space,and then print according to its topological relationship.The basic part of the model still uses plane printing,which weakens the ladder effect to the greatest extent without sacrificing the molding efficiency.Taking the above algorithm as the core,this paper develops a slicing software framework for STL model by using MATLAB,which includes five processes: file reading,contour extraction,layer object generation,path planning and Gcode export.The slicing software is embedded with fast external adaptive and curved-layer hybrid slicing methods.The Gcode generated by the software is printed on a 3D printer,and the running results of the software are analyzed The algorithm is verified by experiments.The experimental results show that the algorithm is accurate and feasible,the slicing efficiency is higher.The designed software function can meet the requirements of 3D printer.At the same time,this paper summarizes the innovation and shortcomings of this paper,and points out the future research and development direction of slicing algorithm in rapid prototyping,which provides a useful reference for further depth study of slicing algorithm. |
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