Simulation Analysis And Experimental Study On Micro-droplet Jetting System Of Pneumatic Valve Control Jet Head

Micro-droplet jetting is a technology that forces the fluid material into micro droplets in the nozzle with external pressure. With the development of science and technology and the needs of pruduction, the micro-droplet jetting technology which originate from in ink-jet priting technology has been applied in many new areas,such as microelectronic packaging, micro electro mechanical system, rapid prototying, micro components pruduction, three-dimensional structure manufacture, biological engineering and chemical analysis,etc. However, in these new applications, the injection and distribution of fluid are generally has a higher viscosity. But the existing commercial nozzle from the development of ink-jet printing technology can jet with low viscosity fluid body only. For high viscosity fluid micro-droplet jetting, at present mainly adopts valve control jet head. Pneumatic valve control jet head is one of the valve control jet head, it has a high requirements for the jetting precision and stability in the process of its application. In different application fields, the different volume of droplet are needed. Sometimes even in the same field its volume is variable. So in the pneumatic control valve micro-droplet jetting technology, how to control the volume of spray droplets becomes very meaningful.In order to make the micro-droplet jetting technology of pneumatic valve control jet head can achieve accurate control of the droplet volume in the application process, the mainly research of micro-droplet jetting system of pneumatic valve control jet head is done. The full paper around the theme of simulation analysis and experimental study on micro-droplet jetting system of pneumatic valve control jet head, specific work and research is as follwos:(1)This paper expounds the working principle of pneumatic valve control jet head and analysis mechanism of the roplets in process of injection and describes fluid mechanics based micro droplet jetting process.(2)The micro-droplet jetting process of the pneumatic valve control jet head is simulatd. The simulation can be divided into two steps. First of all the fluid movements are analyzed after the striker hit the nozzle. Then the droplet formation process in nozzle is simulated after the striker hit the nozzle. Combined with the two simulation results, get the qualitative relations between the size of the droplet diameter and the driving pressure and stroke length.(3)In order to expand droplet spray test and obtain the relevant experimental data, the droplet spray experiment platform is bulit. This experiment platform is mainly composed of drive pulse controller, pressure control system, temperature control system, pneumatic control valve type of nozzle and image acquisition system. Experimental platform was introduced in detail in each subsystem design thought and implementation method, and finally completed the assembly and debugging of the whole system.(4)Based on experiment platform, the injection experiment of E51 epoxy resin was carried out. A complete droplet formation process and some special cases are got in the process of micro-droplet jetting. Then by using the method of theory combining with the actual,explain why these phenomena appear. Then change the stroke length, back pressure, drive pulse width and drive pressure value in different injection experiment, the experimental results show that stroke length, back pressure, drive pulse width and drive pressure value the four factors are the main factors influencing the micro-droplet diameter.