| Electromagnetic force driven droplet injection technology can be widely used in automotive manufacturing,microelectronics engineering,micro-machinery,energy industry and other areas,which can achieve its high accuracy,fast response,fine positioning and other characteristics.Electromagnetic micro spray technology can conveniently control the current pulse width,realize the liquid rapid Drop-on-Demand and liquid feed,reduce waste,cut jet costs,accurately control the amount of injection,and improve the quality of liquid spray.In order to optimize the micro droplet shape and size of the valve body and the nozzle device,we improve the injection efficiency and particle injection quality.This article is based on the electromagnetic theory and fluid theory,using ANSYS finite element numerical simulation software to simulate the electric magnetic flow coupling on molten liquid of value body's molten tin bath,and the Fluent analysis module of workbench platform was used in the numerical simulation of nozzle fluid,analysis of shape,size of the jet velocity and the jet quality influence.As a result,we process corresponding shape size of value bodies and nozzles and they all would be tested and experimented.During the simulation analysis,first of all,the unknown and required parameters would be acquired by the measurement and simulation of experiments.We make the solder as jet material,measuring the density and conductivity of molten tin each is6981.73 m.kg and4105.2?-1mS.at the temperature of 250?,and measuring the coercive force of the designed permanent magnet is 8121449-1A.m.Secondly,based on the analysis of ANSYS software,using the orthogonal simulation method,comprehensive considering the energy utilization rate,injection efficiency,body volume and positioning accuracy and nozzle clogging problems.We set valve andnozzle model shape and dimension.Using the load transfer coupling method,and making the pressure value as the basal evaluation,we respectively do numerical simulation for structure size of the valve and nozzle,and analyze the effect of valve body and nozzle size on injection efficiency and injection quality.The results show that the the main factors affecting injection are the flow passage of valve body shape,length and shape of molten tin.The influencing factors after the main factors are the thickness of molten tin bath and the diameter of the nozzle,and solder bath height and nozzle height are the common factors.There comes a conclusion that the optimal valve body shape and size combination are transition shape flow channel,the length of the molten tin bath is 36 mm,the thickness is 7 mm and the height is up to 44 mm.The optimal nozzle flow passage shape size combination is transitional flow channel,and its height is 0.5 mm and aperture is 150 mm.Then,we assemble optimized valve body and nozzle,and carry out multi-field coupling analysis,finally we get the nozzle exit speed is 1.19501 m.s-.During the experimental study,firstly,according to the simulation results,considering the problems of sealing,insulation,precision and others,we design and process the optimized valve body structure,as well as the copper electrode paired with valve body,which is coated Teflon treatment.The nozzle is designed as the composition of the tungsten nozzle core and Aluminum Alloy nozzle.Secondly,based on the simulation parameter measurement,setting on the permanent magnet coercive force is 8121449-1A.m,voltage value is 8 V,pulse width is 6 ms,and the heating temperature is 250?.We optimized nozzle and optimized valve body and nozzle experiment respectively,and the experimental results would be analyzed by Origin software.The results show that when the micro jet device is not optimized,or only optimized nozzle or optimized valve body and nozzle,the average values were0.49791 m.s-,0.594461 m.s-and 1.108661 m.s-.That also means that after the optimization of the nozzle's speed is increased by 19%,and both optimized valve body and the nozzle compared with the micro spraying device of only optimized nozzle,the speed is increased 86%;the average particle size of solder respectivelywas 792 um,373 um and 299 um,and its variances respectively were 98169 um,13504 um and 687 um.The roundness of jet particles rises,and the consistency and uniformity are improved obviously.The speed of optimal device simulation exit is1.19501 m.s-,which is compared with the speed of the measured exit,and we know the error is 9%,so the simulation results are in good agreement with the experimental results.It shows that the simulation model of parameter setting is reasonable,and the feasibility of the simulation model is verified. |
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