Abstract: To address the phenomenon that ultrasonic-assisted machining might improve the microstructural properties of high-strength aluminum alloy surfaces by forming micro-scoring surfaces on the workpiece surfaces, an experimental study on the microstructure of surfaces milled by single-excitation rotary ultrasonic longitudinal torsion composite milling was conducted: the effects of machining parameters on the water contact angle were analyzed based on the water contact angle theory and the kinematic theory of longitudinal torsion milling; secondly, a single-excitation ultrasonic longitudinal torsion milling test platform was built, and the orthogonal method was used to study the effects of different machining parameters on the surface roughness, milling forces and surface wetting performances. The results show that the surface quality is best when the ultrasonic amplitude is as 4 μm, and the cutting speed and feed are positively correlated with the surface roughness and water contact angle; the surface water contact angle under ultrasonic machining mode is larger than that of the normal mode, and the surface water contact angle machined by low amplitude is larger than that of high amplitude during ultrasonic machining. And the differences between the surface water contact angle machined by high amplitude and low amplitude are not significant when the speed reaches a certain amount. Suitable machining parameters under the ultrasonic longitudinal twist processing method may reduce the roughness of the machined surfaces and change the wettability of the surfaces.

Key words: ultrasonic milling, aluminum alloy, roughness, wettability

摘要： 针对超声辅助加工在工件表面形成微刻划表面可以提高高强铝合金表面的微结构性能的现象，进行了单激励旋转超声纵扭复合铣削表面微观结构的试验，基于水接触角理论和纵扭铣削运动学理论分析了加工参数对水接触角的影响；搭建了单激励超声纵扭铣削试验平台，采用正交试验法研究了不同加工参数对表面粗糙度、铣削力以及表面润湿性能的影响。结果表明：超声振幅为4 μm时表面质量最佳，切削速度和进给量与表面粗糙度和水接触角呈正相关的关系；超声加工方式下的表面水接触角较普通方式更大，而在超声加工时低振幅加工比高振幅加工的表面水接触角大，当转速达到一定值时，高振幅和低振幅所加工的表面水接触角差别不大。合适的加工参数条件下超声纵扭加工方式可以降低加工表面的粗糙度，改变表面的润湿性。

关键词: 超声铣削, 铝合金, 粗糙度, 疏水性