Research On Automatic Generation Technology Of 3D Printing Support Based On FDM

As a new processing and manufacturing technology,three-dimensional printing technology has the characteristics of wide raw material,fast processing speed,high customization and high flexibility,which is essentially different from the traditional machine tool processing methods.Fused Deposition Modeling(FDM)is currently one of the most popular 3D printing technology in the market.The technology is finished with thermoplastic material as row material and printed by layer.Since the fuse must be deposited on an existing object,the floating part must be supported by a supporting structure.The addition of support structure is one of the key technologies in 3D printing.There are many problems such as waste material,hard to remove and damage model surface.In view of the above problems,this paper studies the support structure generation algorithm based on FDM type 3D printer.First,read the STL file that stores model information.Because of the large redundancy in the coordinates of the STL file and the disordering and disordering of the coordinate points,this paper establishes a non-repetitive coordinate point table by hash function,and then establishes the topological relation between the vertex and the triangle face.Aiming at the shortcomings of existing supporting structures,such as huge volume,waste materials and difficult to support removal,a sparse cylindrical support structure generation algorithm is proposed.By measuring the critical inclination angle of the laboratory printer by experiment,the set of triangular facets to be supported in the model is identified by the relation between the critical angle and the angle of the triangle slanting angle.The adjacent triangular face is merged into a separate area by the method of fast facet merging.An optimized edge length adaptive sampling method is proposed for each supporting area,and a reasonable support point set is obtained on the projection plane.Then the support point set of the model surface is obtained by the intersection of the ray and the model,and the support structure is formed by the support point set perpendicular to the support point.On the basis of the columnar support structure,a second type of support structure,the tree-shaped support structure,is proposed in this paper.The support structure has less material characteristics than the columnar support structure.First,the set of points to be supported is obtained based on the angle of inclination of the triangular face sheet,and then the lower node of the support structure is obtained by calculating the intersection point of the support cone corresponding to the support point,and the support structure is generated layer by layer.By stratifying the support structure and optimizing the polygonal section of the support structure,the stability of the support structure is improved.Finally,the printing experiments of different models are done by the existing printers in the laboratory,and the experimental results are analyzed and compared to verify the feasibility of the algorithm.The experimental results show that the columnar support structure proposed in this paper can reduce material consumption by about 19% compared with the thin-walled support generated by Cura software,The tree support structure proposed in this paper can reduce the material consumption by about 22% and 4.5%,respectively,compared with the thin-walled support structure and the tree shaped support structure generated by the MeshMixer software,The two supporting structures generated in this paper achieve design expectations in terms of stability,divestiture and printing time.