摘要
针对静电空气喷涂成膜过程中,荷电气液两相流耦合作用下涂料液滴运动轨迹复杂,使得被喷涂工件成膜特性不明晰,涂料转移率有待提高的迫切需要,提出以环形电极和静电空气喷枪针形电极组合为针-环组合电极的静电喷涂方法。基于电磁流体力学,采用欧拉-拉格朗日法求解气液两相流输运方程和涂料液滴撞击粘附模型,分别以针-环组合电极的环中径和环截面直径为变量,对针-环组合电极静电喷涂过程的喷涂计算域流场和电势进行仿真分析,对涂料粒径分布、涂膜厚度分布及涂料转移率进行计算,并对针形单电极静电喷涂进行实验。结果表明:在采用针-环组合电极进行静电喷涂的情况下,沉积在被喷表面的涂料转移率相比于针形单电极提高了5.04个百分点,环形电极的中径和截面直径与沉积在被喷表面的膜厚和涂料转移率密切相关。当环形电极中径为50 mm,截面直径为6 mm时,针-环组合电极形成的电场不仅有助于改善涂料的雾化效果,令膜厚分布更加均匀,而且有助于调控静电场带电液滴的运动方向,使得空气流场分布沿极针径向扩散减小,令涂料转移率提高。针形单电极喷涂实验中测得的喷涂工件表面涂膜厚度分布与仿真计算一致。
Aiming at the unclear film-forming characteristics on workpiece during electrostatic air spraying process due to the complex motion trajectory of paint droplets caused by the coupling effect of gas and liquid phases,and the urgent need to improve the paint transfer efficiency,an electrostatic spraying method in combination of a ring electrode and the needle electrode of electrostatic air spray gun was proposed.Based on electromagnetic fluid dynamics,the gas and liquid phase flow transport equations and paint drop impact adhesion model were solved by the Euler-Lagrange method.The variation of flow field and potential in the calculation domain for electrostatic spraying using the needle-ring electrode with the pitch diameter and cross-section diameter of the ring electrode were simulated and analyzed.The distribution of paint droplet size and coating thickness and the paint transfer efficiency were calculated.The electrostatic spraying experiments were performed with single needle electrode.The results showed that the paint transfer efficiency on the sprayed surface when using the needle-ring electrode was increased by 5.04 percentage points as compared with that using the needle electrode.The coating thickness distribution and paint transfer efficiency deposited on the sprayed surface are related to the pitch diameter and cross-section diameter of the ring electrode.When the pitch diameter and cross-section diameter of the ring electrode are 50 mm and 6 mm respectively,the electric field formed by the needle-ring electrode not only helps to improve the atomization of paint,improving the uniformity of coating thickness distribution,but also facilitates the regulation of the motion direction of electrostatically charged paint droplets,reducing the diffusion of air flow field along the radial direction of the needle electrode,improving the paint transfer efficiency.The measurement result of the coating thickness distribution on the workpiece sprayed with single needle electrode is consistent with the simulation result.
作者
张淑珍
贾伦
金炅德
侯致远
马欢欢
李笛
ZHANG Shuzhen;JIA Lun;JIN Jiongde;HOU Zhiyuan;MA Huanhuan;LI Di(College of Mechanical and Electrical Engineering,Lanzhou University of Technology,Lanzhou 730050,China)
出处
《电镀与涂饰》
CAS
北大核心
2023年第8期45-51,共7页
Electroplating & Finishing
基金
国家自然科学基金(52265065)。
关键词
静电空气喷涂
针-环组合电极
雾化
涂膜厚度分布
转移率
计算流体力学
仿真
electrostatic air spraying
needle-ring electrode
atomization
coating thickness distribution
paint transfer efficiency
作者简介
张淑珍(1969-),女,副教授,研究方向为静电喷涂及喷涂机器人。
