Design and Experiment of an Internal Mix Airblast Spray-Coating Valve

In order to attain high speed and high precision in modern electronic coating, an internal-mix airblast spray-coating valve was designed. The device used a reciprocating piston to control the supply of liquid, which was mixed with gas in the atomization chamber and was sprayed out from the nozzle. The movement of gas and liquid in the spraying nozzle was first analyzed. The structural parameters of the spraying nozzle are designed and optimized via finite element software. Finally, the experimental platform was set up to test the performance of the optimized spray-coating valve. Results show that supply pressures of atomizing gas and fluid all directly affect the coating layer width and thickness, and that the spraying regularity between them was obtained. When the fluid viscosity, atomizing air pressure, fluid supply pressure, and spraying height were 200 cps, 30 kpa, 20 kpa, and 8 mm, respectively, the rate of the moving platform was 100 mm/s, the length of the coating layer was 100 mm, the coating layer width was 9.4 mm, the coating layer thickness was 230 μm, and the average coating mass was 186 mg. The accuracy of the coating mass can be controlled at less than 5%.