Research On Unidirectional Large-size Integrated Fused Deposition Technology And Influencing Factors On Tensile Strength

The fused deposition molding technology has become one of the fastest developing three-dimensional printing technologies because of its low printing cost,the use of various types of raw materials,and small volumn,etc.However,some shortcomings limit the development of fused deposition molding technology,how to integrally print large-sized parts and improve the mechanical properties of the parts has become an urgent problem to be solved.In this paper,the Unidirectional Large-Size Integrated Fused Deposition Technology is proposed to solve the above problems.The relationship between the tensile strength of unidirectional discontinuous melt deposited specimens and the extruder temperature,the pause time of the extruder,the printing speed and the thickness of the layers was obtained through experiments and computational analysis.The feasibility of the Unidirectional Large-Size Integrated Fused Deposition Technology was explored.Then,the magnitude and distribution of longitudinal and equivalent residual stresses of unidirectional FDM parts under two different scanning paths are simulated by ANSYS "element life and death" technology and APDL.Finally,four-axis FDM equipment is developed for one-way large-scale integrated melt deposition technology,and the integrated printing of one-way large-scale parts is carried out,which verifies the feasibility of one-way large-scale integrated melt deposition technology,and then compares with the performance of separated printing bonded samples to verify the superiority of this technology.In this paper,The integrated 3D printing process for one-way large-size parts can print larger one-way large-size parts only change the printing range of the axis where the movable printing board is located and add the movable printing board.Then the unidirectional discontinuous samples printed by ABS,PC and E-MA-GMA were analyzed by univariate and orthogonal experiments.Then we summarize up the relationship between the process parameters and the tensile strength of unidirectional discontinuous melt deposition samples.We found out the optimum technological parameters,that lower extrusion head temperature and lower layer thickness were beneficial to printing FDM parts with higher density.The improved scanning path reduces the longitudinal and equivalent residual stresses andreduces the fluctuation times of high stresses of FDM parts by reducing the cooling temperature difference.The work presented in this paper provide reference significance for the selection and optimization of FDM technology scanning path,and also provides a solution for improving the quality of FDM products.The fourth axis of this three-dimensional printer is the X2 axis,and the superposition structure is adopted.In control,we use T0 and T1 to distinguish the G code executed by X1 and X2 axes.The one-way large-size parts with clear outline,uniform quality and high precision can be printed through this three-dimensional printer.