Design and simulation analysis of an extrusion structure based on screw extrusion 3D printing

In response to the problems of 3D printing, such as uneven wire discharge and easy clogging of printing nozzles in FDM (Fused Deposition Modeling) printing technology, this paper develops a screw extrusion 3D printing melting deposition system based on simulation. The simulation results show that the maximum deformation of the screw occurs at the tail end, with a maximum value of 0.04 mm, while the fluid pressure and the pressure on the surface of the screw gradually increase along the direction of extrusion, and the maximum pressure occurs near the nozzle, with a value of 0.13 MPa. The fluid pressure is positively correlated with the screw speed and negatively correlated with the screw pitch. The fitting formula is obtained by numerical simulation of the screw speed and the flow velocity at the nozzle outlet. Using a self-made screw extrusion 3D printing equipment, relevant experiments are conducted to explore the influence of different layer thicknesses and line spacings on the mechanical properties of printed samples, as well as the influence of printing speed on surface quality. It is found that layer thickness has a significant impact on the bending strength of printed samples, with a maximum value of 24.74 MPa and a minimum of 19.21 MPa. The bending strength decreases by 28.79 % from 0.6 mm to 1.0 mm layer thickness. The line spacing has a significant impact on the tensile strength of printed samples, with a maximum value of 27.22 MPa and a minimum of 21.16 MPa. As the printing speed increases, the surface roughness of the printed piece also gradually increases from Ra = 389.28 mu m at v = 30 mm/s to Ra = 535.45 mu m at v = 70 mm/s, an increase of 37.55 %.