| With the rapid development of the 3D printing industry,the fused deposition modeling technology has developed into one of the most mature forms of rapid prototyping.The FDM line-type plastic 3D printers,with its high printing accuracy,the advantages of convenient operation is widely used,but its further promotion development is limited by material cost and material type.This topic innovatively develops 3D printer with industrial plastic particle as raw material.It is of great significance to solve the problem of material cost and material type.In this paper,the screw plastic particles 3D printer as the object of study,the machine has been optimized to solve its feed blockage,uneven silence,poor stability of persistent and other aspects of the problem.Based on the DEM-CFD coupling model,firstly,this paper simulates the motion,force and distribution of the plastic particles at different feed angles and rotational speeds,and uses the simulation data as the basis for the evaluation of the subsequent optimization scheme.At the same time,the particle transport process under fillet feeding and tangential feeding is simulated,and the influence of the two optimiza tion scheme on the stress and the distribution uniformity of the particles is analyzed.And the visualization experiment of the particle transport process is carried out to verify the accuracy of the model.Then,the Euler two-phase flow model and the melt-solidification model were used to simulate the original extruded head and the new extruder head,and the optimization degree of the new extrusion head in the temperature distribution,the distribution of molten material,the flow resistance and the velocity vector of the original extruded head in the natural working condition,the single heat dissipation condition and the double heat dissipation condition are analyzed emphatically.Finally,the sample print experiment on the optimized machine,mainly to explore the effect of print speed and print temperature as well as the effects of thickness on printing quality,is taken to match the optimum printing parameters,finally getting the conclusion that The optimized machine can stably and continuously print qualified samples.Under the fillet feeding scheme,the stress value of the particles is about 10 N to 50 N which is reduced by 50%~80%,and the linear distribution characteristics of particles are improved in a certain range.The tangential feed scheme can theoretically solve the problem of feed blockage,so that the particle stress value is reduced by two orders of magnitude,keeping on the range of 0N to 1N in the whole speed range.The uniformity of the temperature distribution of the new extruder head under natural conditions is greatly improved.The temperature di fference is controlled within 5°C to 10°C,the energy efficiency is doubled to 20.01%,and the heating time and the maximum shear pressure values are reduced by 1/3.At the same time,the temperature of tube can be controlled below the particle melting temperature under the single heat condition and the double heat condition.And the pipe built-in tube can make its temperature further reduced.The optimum printing parameters of the optimized machine are that printing temperature is about 210°C,printing speed is 35mm/s and layer thickness is 0.10 mm to 0.25 mm.The quality of sample is more than doubled before optimization... |
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