Research On Ejection Performance Of Piezoelectric Droplet Ejection 3D Printing Head

In recent years,microdrop injection technology has been rapidly expanding into many fields,among which piezoelectric microjet 3D printing technology has rapidly become a research hotspot because it greatly meets the requirements of modern industrial production miniaturization and automation,but droplet morphology prediction and accuracy control have been difficult to study.In this paper,based on the principle of piezoelectric microdrop jet printing technology,three physical models are established to study the influence of multi-physical field coupling on droplet formation and the law of action in the microdrop jet process,and the indirect coupling method is used to conduct numerical simulation,and the accuracy of the method is verified through controlled experiments to provide reference for the prediction of droplet morphology and the improvement of printing accuracy.Firstly,the response research of the piezoelectric droplet jet printing head is carried out,the mechanical-electrical coupling model is established,the finite element simulation and analysis of the piezoelectric part are carried out,and the influence of the driving voltage and the structure of the piezoelectric element on the wall displacement and velocity is studied.The research shows that the deformation of the vibrating plate determines the volume of the droplet,and the deformation speed determines the velocity of the fluid outlet.Properly increasing the thickness and length of the piezoelectric ceramic is the most beneficial to the formation of the droplet.Secondly,using the indirect coupling study method of piezoelectric microjet printhead,the multiphysical field coupling characteristics involved in the jetting process are analyzed,and the velocities obtained from the piezoelectric-structure-fluid coupling model are calculated as the initial conditions of the gas-liquid two-phase flow coupling model,and the correctness of the model and the indirect coupling method are verified through controlled experiments.The effect of pulse signal on microdrop formation is analyzed,and the laws of driving voltage,waveform and trapezoidal waveform parameters(rise,dwell and fall time)on microdrop formation are studied.In the pulse waveform selection,pulse waveforms with smaller rise time,larger dwell time and fall time should be selected,and the selection of appropriate trapezoidal waveform parameters will be helpful to improve the printing accuracy.Finally,the multi-physics coupling characteristics and influencing factors of the droplet forming process are analyzed.Based on the indirect coupling method,the droplet generation under different fluid physical properties(surface tension,density,viscosity)and nozzle structure conditions is studied.The optimal parameter range and Z value range for droplet formation,and the sensitivity ranking of the influence of each parameter on droplet formation.By comparing the influence of the physical properties of each fluid on the ejection performance,the effect of surface tension>fluid viscosity>fluid density is affected.