Research On The Structure And Analysis Of The Mixing Process Of The Full Color 3D Printer Mixing Mechanical System

Additive manufacturing technology has seen continuous development and improvement,with 3D printing being an important application of this technology,monochrome or bicolor 3D printers cannot meet user needs,and more and more users need full color 3D printers.Based on the investigation of melt deposition type 3D printing in additive manufacturing,this project conducts research and analysis on key technologies in full color FDM 3D printing technology,such as color mixing screw parameters and screw configuration,pin mixing unit,and other structures.The main research contents are as follows:(1)The study analyzed the extrusion screw structure of injection molding machines by examining the structural features of its feeding section,melting section,and metering section.Based on the structural characteristics of the color mixing screw of the designed full color FDM 3D printer,the screw mechanism is set as a melting section and a metering section.A melt flow flat plate model was established,taking into account the effects of forward flow,reverse flow,transverse flow,and leakage flow on the accuracy of color mixing ratio.Through calculation,the structural parameters of the color mixing screw were determined.(2)Based on the analysis of existing color mixing methods,it is determined to use a pin mixing unit as the color mixing part of the mixing screw.To determine a reliable and efficient color mixing effect,modeling and analysis were conducted on circular,diamond,square.and elliptical pin color mixing structures.After analyzing the drag coefficient and lift coefficient values of fluids passing through different pin shapes,and considering their impact on mixing efficiency,it was concluded that the elliptical pin shape is beneficial for liquid mixing.Furthermore,additional modeling and simulation were performed to assess the impact on mixing efficiency of various factors such as gap-to-diameter ratio,layer spacing,and short-to-long axis ratio of the mixing units.This helped establish the appropriate structural parameters for the mixing component to achieve effective mixing.(3)On the basis of the above research,a comprehensive model of the color mixing screw for full color FDM 3D printing is established,and a computer simulation model of the color mixing flow field is established by combining five different color wire feeding methods and color mixing screw structures.Firstly,the simulation model of the six layer color mixing unit group was calculated for the flow field of liquid-liquid two-phase flow,and the calculation results showed that its color mixing effect can meet the corresponding requirements.On the basis of multiphase flow analysis,the fluid solid coupling mechanical analysis was carried out for the load on the mixing screw during the mixing process.The results showed that the stress in some areas of the mixing screw for the six layer mixing unit group was too high.At the same time,the load torque it is subj ected to was analyzed,which is relatively large.(4)In response to the problems with the mixing screw of the six layer mixing unit group,the screw structure of the five layer mixing unit group was designed and modeled and analyzed.The analysis results demonstrate satisfactory color mixing effectiveness.Additionally,a fluid-structure coupling mechanics analysis was conducted based on multiphase flow analysis.Calculations showed that stress remained below the corresponding strength levels.Simultaneously calculated the load torque,which is also relatively large.And based on the actual load torque,the color mixing system has been improved by adding a reducer and increasing the output torque on the basis of the original stepper motor direct drive,which can meet the system requirements.(5)On the basis of research,a color mixing system was designed and an experimental platform was assembled.Through experiments,it was found that the mixing screw mechanism of the five layer mixing unit group can work,indicating that the output torque meets the requirements.At the same time,four sets of different color model color blocks were 3D printed using the constructed experimental platform.The color information of the printed modules was photographed and extracted.The color information of 10 points was collected from different positions on the same color block,and the range between these ten points R,G,and B was calculated.The results showed that the colors on each point on the four color block models printed in 3D were basically the same,indicating the effectiveness of the color mixing system.