螺杆挤出式3D打印机结构设计与仿真分析

Structural Design and Simulation Analysis of Screw Extrusion 3D Printer

分析了传统桌面级FDM型3D打印机与螺杆挤出式3D打印机的挤出原理,为提升桌面级FDM型3D打印机对打印材料的兼容性并降低打印材料的制作成本,设计了螺杆挤出式3D打印机新结构,具有螺杆与机筒便捷拆换功能。结合设计计算获得了适用于打印丙烯腈-丁二烯-苯乙烯共聚物(ABS)材料的螺杆计量段结构,在螺杆低转速与小型化的要求下,可实现小流率高精度打印并可通过提高转速获得更高的流率。通过仿真实验的方法,分析了计量段熔体的速度场、压力场以及剪切速率场的特征。使用最小二乘法,得出了螺杆转速与出口流率对应的回归方程,验证了计算结果的合理性。结果表明,螺杆挤出机构能够适用于3D打印,可降低打印成本并拓宽可打印物料的选择范围,并可通过对螺杆转速的控制实现对物料挤出流率较为精确的调节。

The extrusion principle of traditional desktop FDM 3D printer and screw extrusion 3D printer was analyzed.To improve the compatibility of desktop FDM 3D printer with printing materials and to reduce the production cost of printing materials,a new structure of screw extrusion 3D printer was designed with a function of convenient disassembly and replacement of screw and barrel.A screw metering section structure suitable for the ABS printing materials was obtained through combining the design calculation.Under the requirements of low rotating speed and miniaturization of the screw,the high-precision printing with a small flow rate could be realized,and a higher flow rate could be obtained through improving the rotating speed.The characteristics of melt velocity field,pressure field and shear rate field in the metering section were analyzed by means of the simulation experiment.The regression equation regarding the screw speed and outlet flow rate was obtained through a least square method,and the rationality of the calculated results was verified.The results indicated that the screw extrusion mechanism was suitable for 3D printing.This mechanism can reduce the printing cost,widen the selection range of printable materials,and realize the more accurate adjustment of the material extrusion flow rate through controlling the screw rotation speed.