A New Type of 3D Printing Molding Equipment: Overall Structural Design and the Numerical Simulation for the Flow Field Characteristics of its Screw Module

Considering the problems faced by Fused Deposition Modeling (FDM) 3D printing equipment, including limited consumables choices and unstable extrusion rate as well as difficult prints precision control, etc., a new type of 3D printing molding equipment was designed following the current screw extrusion technology combined with 3D printing molding mechanism. Also, the optimal matching relation between the rotational speed of the screw, which is the core of the equipment, and the feed rate of the nozzle was determined. The POLYFLOW, the software of finite element numerical simulation, was employed for analyzing the performance of the screw module under different working conditions. The result revealed that the outlet fluid pressure derived from the theoretical calculation (1.48 MPa) was close to the simulation value of 1.51 MPa, and the volumetric flow rate at the outlet derived from theoretical calculation 3.51 x 10(-8)(m(3)/s) was close to the value obtained from simulation (3.18 x 10(-8) (m(3)/s). Those findings indicated that the material could be extruded at a constant output rate; with the increase of the screw lead size, the pressure build-up capacity of screw improved, and the pressure fluctuation and velocity change became more intensive; therefore, the lead within the range of 24 similar to 36 mm should be the suitable choice for the application in actual production; the reduction of the rational speed resulted a lower shear rate, therefore, the screw rotational speed should be optimized within the reasonable range of 8 similar to 15r/min (N-max similar to N-min) and the feed rate of nozzle should be selected within the range of 1043.33 similar to 746.24 mm/min (V-Fmax similar to V-Fmin).