高速超声振动切削钛合金可行性研究

Feasibility Study of High-speed Ultrasonic Vibration Cutting Titanium Alloy

钛合金由于其出色的机械性能广泛的应用于航空航天结构组件中。但较低的机械加工性使得钛合金切削速度低,即使在使用先进的切削刀具时,也因切削高温而难以进行高速切削加工。断续切削是一种有效地降低切削温度和改善切削质量的方法,作为典型的断续切削方法,传统超声振动切削(Traditional ultrasonic vibration cutting,UVC)和椭圆超声振动切削(elliptical ultrasonic vibration cutting,EUVC)已取得了显著的加工优势。但振动切削临界速度限制了它们的应用仅在低速切削场合。因此一种新的超声振动切削方法被提出,即高速超声振动切削(High-speed ultrasonic vibration cutting,HUVC),此时刀具的振动方向与进给方向平行。当切削速度远远超过UVC和EUVC方法的临界速度时,刀具和工件依旧可以在一定的条件下实现分离。从而HUVC方法实现了宏观上的高速切削和微观上的断续切削,提升了钛合金的切削加工性。首先,HUVC方法的原理在文中给出,随后通过一系列使用普通切削(Conventional cutting CC)方法和HUVC方法的高速切削Ti-6Al-4V合金的对比试验来验证HUVC方法的可行性。试验结果表明,因刀具磨损的显著下降,HUVC方法的刀具寿命可最大提升300%。此外,相比CC方法,HUVC方法的切削效率可以显著提升90%,切削力最大下降50%并在连续的切削加工过程中获得更佳的表面质量。

For a series of unique properties, titanium alloy is widely applied in aviation and aerospace fields. However, the poor maehinability makes high-speed machining titanium alloy hardly perform as expected even with advanced tool materials due to the high cutting temperature. Intermittent cutting could be an effective method to decrease the cutting temperature and improve the cutting performance. As typical intermittent cutting methods, traditional ultrasonic vibration cutting （UVC） and elliptical ultrasonic vibration cutting （EUVC） is achieved significant advancements. However, the critical cutting speed confines them to the field of low speed machining. A new type of ultrasonic vibration cutting is proposed, i.e. high-speed ultrasonic vibration cutting （HUVC）, in which the vibration is always along with the feed direction. The separation of the tool and workpiece can be realized under some certain conditions although the cutting speed exceeds far away from the critical speed of the traditional UVC and EUVC methods. As a consequence, it realized high speed cutting on a macro level and intermittent cutting in the micro, and improved the machinability of titanium alloy. Firstly, a model of HUVC process was established. Then the feasibility of HUVC method for cutting Ti-6AI-4V is verified experimentally compared with conventional cutting （CC） and traditional ultrasonic vibration cutting （UVC）. The results demonstrated that tool life in HUVC are extended by 300% in an optimal situation due to the significantly tool wear reduction. Besides, the cutting efficiency is increased by 90% and cutting force is reduced up to 50% obviously compared with CC method. Furthermore, better surface roughness improvement in a successive cutting process are also achieved.