Numerical Simulation And Experimental Investigation Of Metal Droplet By Pneumatic Drop-on-demand

The micro-droplet jetting technology was developed in the 19 th century and developed rapidly in the 21 st century.The theory of micro-droplet jetting technology is that,the external force acts on the surface of the molten metal in the crucible,and drop on the depositional platform.The micro-droplet jetting technology can be divided into continuous and drop-on-demand.The drop-on-demand jetting can produce uniform micro-droplets,so that it has a broad application prospects in the production of solder particles,electronic packaging of MEMS and the rapid forming of metal parts.In this thesis,firstly,FLUENT is used to simulate the process of pressure oscillations in the crucible and the formation process of metal micro-droplets under the action of gas pulse.The variation of pressure field and velocity field in the formation process of the droplets is selectively analyzed.By changing the system parameters like pulse width and gas pressure,the characteristics of the metal micro-droplet's jetting process are obtained.Then,design the jetting system according to the characteristics of tin alloy melt by drop-on-demand.The design of “computer + data acquisition card + solenoid valve” is used to drive the droplet jetting.The data acquisition card sends an electronic pulse signal to the solenoid valve,which controls opening and closing of the solenoid valve,and converts the electronic pulse signal into the gas pulse signal.The design of “computer + high-speed camera + background light source” is used to acquire the image information,and the design of “computer + motion controller + deposition platform” is used to realize the motion control.The design of hardware system,software system and auxiliary system are completed,and the whole system was integrated.Lastly,experimental verification is carried out using the jetting system by pneumatic drop-on-demand,and uniform micro-droplets with good sphericity are acquired.The results show that the experimental results and numerical simulation results are consistent.The image information of the jetting process is acquire,an d the information of the jetting process is extracted and analysed.The influence of different system parameters on the formation of droplet is studied through the jetting experiment.The deposition printing of one-dimensional line,two-dimensional lattice pattern and three-dimensional samples are completed.