Research On Support Automatic Generation Algorithm Based On FDM

Rapid prototyping technology is a major achievement in the development of manufacturing technology in recent years.It has got rid of the dependence on machine tools and molds,and uses layer-by-layer stacking to process parts,which greatly reduces the parts manufacturing period.Fused deposition modeling(FDM)is one of the most mature and widely used technologies in rapid prototyping technology.FDM mainly uses STL files as model carriers,which store data compactly and facilitate reading and writing.In order to solve the problem that the topological relationship between the triangular facets is lost when the 3D model is converted to STL files.In the process of reading and analyzing STL files,a fast topology reconstruction algorithm based on half-edges structure and hash table is proposed.In the process of reading data,a point table without repeat posit-ion information is established through a hash table,and a collection containing half-edges in which no adjacency facets are added is maintained therein.According to the set and topology algorithm,the topological relationship of the facets is improved,and the topological relationship of the facets is quickly established in the process of reading data.Due to the forming characteristics of the layer-by-layer processing of FDM forming technology,the suspended parts of the model depend on the supporting structure to assist the forming,By studying the existing cylindrical support structure,the following improvements are proposed: different sampling methods are adopted for different suspension structures,and the unordered triangular facets,to be supported are combined into regions to be supported,and then the lowest point diffusion sampling algorithm is used to obtain the set of points to be supported;through the support column through-mold detection algorithm to optimize the support generation scheme,and choose ordinary upright support,oblique support and model surface support according to the situation;optimize and adjust the support structure to increase its stability while reducing damage to the model surface.In order to further reduce the material loss of the support structure,the tree-shaped support structure was optimized and studied to increase the generation speed of the existing tree-shaped support and the stability of the support structure.Select the highest point in the set of points to be supported and the point with the shortest horizontal distance,generate cones for the two points according to the printing critical angle,then obtain the lower support points,and complete the generation of the entire support tree in a recursive manner.Finally,the STL files of the column support structure and tree-shaped support structure are realized and output after merging with the model files.Through the actual printing experiment,the feasibility of the column support and the tree support in this paper are verified,both of which can play a supporting role in the suspended part of the model.Compared with the thin-walled support generated by Cura software,the treeshaped support structure in this paper can effectively reduce the loss of materials and printing time,and reduce the difficulty of peeling off the support structure.