45钢/锡铅合金复合结构熔融沉积中熔滴过渡行为

面向45钢/锡铅合金复合结构熔融沉积过程中的锡铅合金熔滴与钨极惰性气体保护焊（TIG）焊接熔池的匹配性需求，基于有限差分方法，采用流体体积法（VOF）建立微喷熔滴形态演变过程数值计算模型，分别研究压电驱动式熔滴微喷过程中压电激振驱动参数和喷头内结构参数对于产生熔滴的尺寸及速度的作用和变化规律. 研究发现，当喷孔直径为0.5~0.6 mm，喷孔深度为5~6 mm，环隙为4~5 mm时，锡铅合金熔滴具有较高的球形度，熔滴可控性较好. 压电陶瓷激振频率和驱动行程对于锡铅合金熔滴尺寸影响不明显，熔滴速度随激振频率和驱动行程的增大而增大. 对比数值计算结果与实验结果，发现锡铅合金熔滴尺寸与熔滴速度最大误差均小于10%，表明利用数值计算模型对熔滴微喷过程进行分析较可信.

Droplet transfer behavior in fused-deposition of 45 steel/tin lead alloy bimetallic structures

A numerical calculation model for the morphological evolution process of micro-droplet ejection was established by the method of volume of fluid (VOF), in order to meet the requirements of tungsten inert gas welding (TIG) welding pool and tin-lead alloy droplet matching in 45 steel/tin lead alloy bimetallic structures fused-deposition fabrication process. The effects and the change rules of driving parameters of piezoelectric vibration and internal structural parameters of nozzle on the size and velocity of the droplet were described in the process of piezoelectric driven droplet micro-ejection. Results showed that the droplets had a high sphericity and good controllability in the case of 0.5~0.6 mm nozzle diameter, 5~6 mm nozzle depth, and 4~5 mm annular gap. The influence of excitation frequency and driving amplitude on droplet size was not obvious, and the droplet velocity increased with the increase of excitation frequency and driving amplitude. Comparison between numerical and experimental results showed that the maximum error of droplet size and droplet velocity was less than 10%, indicating that the numerical model is reliable to analyze the droplet micro-ejection process.