超声振动方向对TC4钛合金铣削特性的影响

为充分发挥超声铣削钛合金的优势，改善钛合金的加工效果，增强表面服役性能，分别对刀具和工件施加超声振动，以寻求合适的振动方向和加工参数。理论推导了侧刃断续切削时的临界速度，试验研究了不同振幅和切削速度对表面形貌、切屑形态、切削力和刀具磨损的影响，同时探究了表面微织构对摩擦特性的影响。试验表明在两种振动方向下，增大振幅均使切屑的锯齿化程度降低，并且增加轴向振幅可使锯齿形切屑转变为带状切屑。轴向振动更有利于表面形成微织构、减小切削力、减缓刀具磨损、减小工件摩擦时的磨合时间，但需合理控制切削速度和超声振幅。同时，对切削力进行频谱分析，为工作状态下超声振动频率的测量提供了一种参考方法。

Effect of ultrasonic vibration direction on milling characteristics of TC4 titanium alloy

In order to give full play to the advantages of ultrasonic milling titanium alloy, improve the processing effects, and enhance the surface service performance, ultrasonic vibration is applied to the tools and workpieces to find suitable vibration directions and processing parameters. The critical speed of the side edge interrupted cutting is obtained from the theoretical derivation. The effects of different amplitudes and cutting speeds on surface topography, chip morphology, cutting force, and tool wear are investigated. The relationship between the surface microtexture and the friction characteristics is studied. Tests have shown that in both vibration directions, increasing the amplitude reduces the degree of serration of the chips, and increasing the axial amplitude allows the sawtooth chips to be converted into strip-shaped chips. When ultrasonic vibration is applied in the axial direction, the surface microtexture is more easily obtained, while the cutting force is reduced, the tool wear is weakened, and the running-in time of workpiece during friction is reduced. In addition, a method of measuring the ultrasonic vibration frequency under working conditions is proposed by using the spectrum analysis of the cutting force.