Design And Experimental Research Of Piezoelectric Microjetting Valve For Low-viscosity Fluid

The rise of the information industry and its rapid development have led to the progress of human society.It is considered as one of the hallmarks of the third industrial revolution.With the further development of the information industry,the requirements for the Micro-engineering field are also getting higher and higher.With the deepening application of droplet generation technology,the low viscosity micro-injection technology will be gradually applied to OLED display,biomedicine,material molding,microelectromechanical manufacturing,microelectronic packaging,aerospace,genetic engineering and other fields,which further demonstrates the broad application of droplet jet technology.Based on piezoelectric basic theory and micro-injection theory of low-viscosity fluid,this paper develops a low-viscosity fluid micro-injection valve by analyzing the fluid simulation and the structural design and analysis of the micro-injection valve.Repeated experiments verify that the injection valve designed in this paper can make the volume of low-viscosity fluid ejected p L level,the viscosity of the jet fluid can be adjusted between 1 ~ 600mPa·s,and the injection frequency can reach 1200 Hz above.The reserch of this paper is as follows:Firstly,the application prospect of fine jet and the existing micro-jet technology are studied and analyzed.In a comprehensive comparison of existing institutions and enterprises developed jet equipment,found that the use of non-amplified structure of the body will be easier to achieve the function of micro-injection of low-viscosity fluid.Through an introduction to piezoelectric materials and analysis of characteristics of stacked piezoelectric actuators.the piezoelectric stack with small capacitance should be selected to enhance the response speed.And the piezoelectric stack with high resonant frequency should be selected properly to shorten the time it takes to stabilize the calibration displacement.The piezoelectric stack's impact force and displacement can be controlled by the drive power.In addition,the reason why the low-viscosity fluid easily causes the droplet breakage during the jetting process is analyzed.The relationships between visco sity,flow rate,injection volume and structure are analyzed by using the mathematical model and using the theory of micro-injection of collision-impulsive low-viscosity fluid.The flow field simulation was carried out by Fluent software to get the velocity and pressure cloud of the fluid in the nozzle at different time during the collision The influence of various parameters on the trace of the low viscosity fluid was obtained by simulation,which as the theoretical basis for structural design and experimental research.The design and calculation of the prestressing and firing pin recovery of the piezoelectric stack are carried out.It is concluded that two disc springs are required in the structure.The specific structure of the firing pin is designed,and then design the overall structure of piezoelectric low viscosity micro injection valve and low-viscosity fluid feeders;Through the analysis of the stability of the firing pin,the mechanical simulation of the firing pin and the fatigue analysis,it is proved that the firing pin structure is reasonable and the YG-20 material can meet the requirements.Analysis and calculation of the response of the micro-injection valve's motion system shows that the system's response to this structure is higher than that of the amplification mechanism.Finally,the design and construction of the micro-injection system with low viscosity fluid are carried out.The kinematic characteristics of the striker are tested.From the test,the response of the striker is faster.During the ascent and descent of the striker,the striker is at a uniform speed.The position of the striker after no jitter,to ensure stable low-viscosity fluid micro-injection;The relationship between the single point volume and the spot diameter when the parameters are changed is plotted and the reason is briefly analyzed;The viscosity range of jetting low viscosity fluid is tested and the viscosity of jetting fluid is measured to fluctuate between 1 ~ 600mPa·s;In the low-viscosity fluid injection into the line test,it can be obtained that the injection valve injection frequency is up to 1200 Hz or more.