Nozzle Study Based On Mixing-color 3D Printer Of FDM Technology

In order to realize the 3D printing of mixed colors,to solve the problems of unreasonable nozzle structure and materials,poor quality of color mixing,poor printing accuracy,and easy clogging of nozzles in the printing process,comparative analysis of branching and integrated three-into-one color mixing nozzles was conducted..Through the Solid Works 3D modeling software,the 3D modeling of the color mixing nozzles is performed in a fine manner.In the Ansys finite element analysis software,temperature and stress fields of the color mixing nozzles are simulated and solved.Comparing with the results of the solution,the design defects of the mixing nozzle are pointed out.Then the nozzle is optimized and the rationality of the optimized design is verified again by finite element analysis.Final print test to verify the print quality and print stability of both print nozzle.In this paper,two single extruder nozzles are used as research objects.The main research contents are as follows:1.Design of branched and integrated color mixing nozzle models.Two kinds of nozzle models were designed using three-dimensional modeling software.The main components of the branch nozzle include radiators,throat pipes,heating pipes,thermistors,and nozzles.The radiator is a cylindrical slice.The heating pipe is placed at the center of the nozzle.The nozzle can be evenly heated.The main component of the integrated sprinkler head has a heating block with respect to the branch nozzle,and the radiator uses a fan-shaped radiator to improve the heat dissipation efficiency.The throat pipe is made of steel material to prevent the PLA from swelling or melting and blocking the nozzle;the heating pipe is placed symmetrically and can Heat evenly.The material mixing chamber in the heating block facilitates the mixing of the material liquid.2.Finite element thermal coupling analysis.Branch-type and integrated sprinklers were respectively imported into finite element analysis software,and then meshed and optimized separately.The quality of the mesh has a great influence on the results of the finite element analysis.Therefore,comparing the quality of several meshes,the branching and all-in-one nozzles use the tetrahedron as the dominant mesh.Using the transient temperature analysis system combined with the structural static analysis system,the former's solution results are used as the input parameters of the latter,thermal coupling analysis is performed on the nozzles,and the advantages and disadvantages of the two nozzles are found out based on the solution results to optimize the design.The structure of the branch nozzle is reasonable,and the heating and heat dissipation performance is good,but the melt flow channel does not have a mixing chamber,and different color supplies cannot be mixed,resulting in poor color mixing printing.The structural design of the integrated nozzle is more complex,the L-shaped design of the melt flow channel is not reasonable,and the nozzle is easy to block,but it has a certain size of the mixing chamber,which is beneficial to the mixing of consumables,and thus is beneficial to improve the effect of mixed color printing.According to the results of the finite element solution,two kinds of color mixing nozzles are optimized.A mixing chamber is designed for the branch nozzles so that the consumables are fully mixed and the mixed color printing effect is improved.Because the radiator design is not reasonable,the cooling effect is not ideal,so the radiator is improved to a uniform diameter.The exposure of the heating tube to the nozzle leads to a high external temperature.On the one hand,it is not conducive to the full use of heat,and on the other hand it is not conducive to heat dissipation,so the size of the heating tube is reduced.Then,since the flow path in the integrated heat block presents an L-shape,which is not conducive to the entry of the wire,and the temperature is lowered,it is easy to cause clogging,so the flow path shape is improved.The temperature of the thermistor is slightly lower than the temperature of the heating block,and does not reflect the temperature distribution of the entire heating block and the flow channel.Therefore,the thermistor is moved from the cylindrical lateral position of the heating block to the central position of the upper surface of the heating block.The position of the gap between the throat and the radiator is still high,and the wire is easily blocked by thermal expansion through this gap,so the gap in the throat is removed.For the deformation analysis of the two nozzles,the effect of temperature on the deformation of the nozzle is only half of the layer thickness,which has little effect on the printing effect.4.Through the finite element thermal coupling analysis of the improved nozzle,and the use of two nozzles for print test to verify the rationality of the optimization.The deficiencies of the two types of nozzles have basically been solved.Printing experiments using the improved color mixing nozzles all improved the effect and quality of mixed color printing.In this paper,the thermal and mechanical coupling fields of two single extruder print heads are compared and analyzed.It basically solves the problem of unreasonable nozzle structure in the printing process,poor color mixing quality,poor printing accuracy,and easy nozzle clogging.The results of this study have important reference value for the design of sprinkler heads of 3D printers based on FDM technology.