Design And Experimental Research Of Polymer Vibrating Jet 3D Printing Equipment

3D printing technology is a technology that has developed rapidly in recent years,and many new molding methods such as fused deposition molding,three-dimensional light curing,and selective laser sintering have emerged so far.The State Council promulgated the "Made in China 2025" strategy,which affirmed the important role of 3D printing technology in China's modern industrial manufacturing and attracted wide attention from various industries.At present,the existing 3D printing of polymer materials is mainly based on fused deposition molding,which has problems such as slow molding speed,low product accuracy,low equipment universality,and high cost of consumables.Therefore,based on the micro drop forming 3D printing technology,a vibration jet 3D printer suitable for high viscosity polymer melt is proposed and designed,which provides new methods and new processes for 3D printing of polymer materials,so as to solve the limitations of 3D printing equipment and technology of polymer materials.The main research contents are as follows:(1)Firstly,based on polymer rheology,the processing properties of polymer were studied;Secondly,the feasibility and conditions of polymer melt droplet injection are analyzed based on droplet injection mechanism and stacking mechanism,which provides theoretical guidance for the design and experimental analysis of subsequent printing equipment.(2)Conduct experimental research on thermoplastic polyurethane elastomer(TPU)and polylactic acid(PLA),which are popular polymer materials in the field of 3D printing in recent years,and use modified multi-walled carbon nanotubes(MWCNTS)and polybutylene succinate,respectively(PBS),modified graphene oxide(GO)for modification.The experiment found that the addition of MWCNTS enhanced the strength and conductivity of TPU PBS and modified GO effectively realize the enhancement and toughness of PLA.(3)Aiming at the high viscosity of polymer,a vibration jet 3D printing equipment was designed.The whole printing equipment consists of six parts: plasticizing device,vibration spraying device,stacking device,servo drive system,temperature control system and cylinder control system.This paper focuses on the core innovation of the vibration injection device,through the specially designed vibration cylinder to drive the high-frequency movement of the stem to achieve the effect of melt injection,and on the basis of the existing 3D printer,other parts are improved.(4)Based on the finite element simulation software FLUENT,the velocity field and pressure field of the nozzle are simulated,and the relationship between the maximum velocity of the nozzle and the movement velocity and displacement stroke of the valve stem is obtained;On the other hand,the VOF model is used to simulate the flow of polymer melt at the nozzle under the action of stem movement and gas back pressure,and the volume fraction of different time steps and the changes of flow rate and viscosity of Newtonian fluid and non Newtonian fluid at the nozzle at a certain time step are obtained.(5)The experiment was carried out with PCL as raw material.Firstly,the influence of different process parameters(screw speed,melt temperature)on the flow rate at the nozzle was investigated;Then the spray experiment was carried out to observe the macro and micro morphology of the ejected material,and the feasibility of the equipment was verified.