Research On The Generation Of Truss Structure Based 3D Printing Lightweight Model

3D printing technology is in a stage of rapid development. Nowadays, the research direction of 3D printing is mainly on the application area. However, there are few studies in the field of lightweight. Lightweight model is the key factor to reduce the cost of 3D printing supplies, and indirectly affect the promotion of 3D printing technology. To this end, this paper proposes a truss structure based lightweight method. The proposed method includes three steps:model hollowing, truss generation and slice contours extraction.In the first chapter, the background and significance of the paper are introduced, and the research status of 3D printing technology is discussed. The STL file format is introduced. Then, the research status of hollowing algorithms for STL and truss generation algorithms are introduced. Researches on lightweight method, hollowing algorithm and truss generation algorithm are discussed. Finally, the content and framework of this paper are proposed.In the second chapter, the proposed hollowing algorithm for STL model is studied. LDNIs (Depth Normal Images Layer) model representation is introduced at first. Current researches of model slicing algorithm is talked, and the weakness of them is pointed out. On the basis of this, a topology network based slicing algorithm is proposed. The proposed slicing algorithm consists of two parts:topology network reestablishment and slicing. Then, current hollowing algorithms are studied. To improve the efficiency of hollowing process, a LDNIs based hollowing algorithm is proposed. In the algorithm, a two-side offset model is established at first. Then, the hollowed model is generated by combining the two-side offset model and the original model together with Boolean operations. Taking the advantage of the high performance of LDNIs in Boolean operations, the efficiency of the proposed hollowing algorithm is improved.In the third chapter, a truss structure based model lightweight method developed. A simplified truss structure representation is developed to separate the design and the generation of truss structures. In most studies, STL is chosen as the data structure of truss structures. However, the efficiency of these approach is low. To this end, LDNIs is used as data structure instead of STL in this paper. At last, the conversion method from LDNIs to the layered contours is proposed to obtain the outline of the lightweight model.In the fourth chapter, the generation and optimization of the printing path of FDM (fused deposition modeling) is studied. In this paper, the ring path is used to improve the surface quality and the scanning line filling path is used to improve the printing speed. Firstly, a fast generating algorithm of scan line path is proposed. Secondly, both type of print paths are optimized to reduce the air time of the nozzle. The printing path optimization method consists of a drilling hole based ring path optimization and a block based scanning line path optimization. Finally, technical specifications of FDM gcode is briefly introduced.In the fifth chapter, the proposed slicing algorithm, hollowing algorithm and truss structure generation algorithm are experimented. Experimental results are compared with the existing algorithms to verify the validity of the algorithms. Also, the effect of lightweight is studied to verify its feasibility.In the sixth chapter, the conclusion and future work are discussed.