MQL Cutting of Difficult-to-Machine Materials with the aids of CAE and Ultrasonic Vibration

为了减少对全球环境的影响，实现制造业的可持续发展，MQL技术在机械加工过程中得到了广泛的应用。在MQL技术中，少量的生物降解油被大量的压缩空气供应。然而，将MQL技术有效地应用于难加工材料的加工还存在一定的困难。本研究从理论和实验两个方面对难加工材料的MQL加工技术进行了研究。为此，对Inconel 718和碳钢S45C进行了超声振动切割和非超声振动切割实验，研制了能精确监测切割温度的刀具，并利用计算流体力学通用程序分析了刀尖周围的油雾流动。在Inconel718精加工中，优化了压缩空气压力、油耗和刀具涂层材料，在相对较高的切割速度(60m/S或更高)下提高了刀具寿命。研制了控制油雾化学需氧量(COD)工具吹气方向的工具。结果发现，这些工具能够减少50%-70%的石油消耗。超声振动在MQL切割中的应用被发现是有效的，特别是在较慢的切割速度下减少凹坑磨损，这在加工较小直径的细长棒材时是不可避免的。利用光刻技术在刀具上制作薄膜热电偶，并在刀具上涂覆硬而薄的TiN薄膜，以实现对刀具温度的精确监控。用这些刀具测量了车削过程中的切削温度。对油雾的流动进行了分析，以便进行调谐和开槽。在开槽过程中，油耗的降低与油雾流动的局部化程度有定量的关系。

To decrease the impact to the global environment and realize the sustainable development of manufacturing, MQL technology, in which a small amount of bio-degradable oil is supplied with plenty of compressed air, has been widely applied to machining processes. However, it is still difficult to apply MQL technology to machining of difficult-to-machine materials effectively. In this study, MQL cutting technology effective for machining difficult-to-machine materials was investigated from theoretical and experimental viewpoints. For this purpose, MQL cutting experiment of Inconel 718 and carbon steel S45C were conducted with and without ultrasonic vibration cutting ; cutting tools for monitoring cutting temperature precisely were developed ; oil mist flow around tool tip were analyzed using a general purpose code of computational fluid dynamics. In finishing Inconel 718,optimization of the pressure of compressed air, oil consumption, and coating materials of tool increased tool life at relatively high cutting speeds of 60 m/s or more. Tools for controlling the blowing direction of oil mist COD tools were developed. It was found that these tools were able to decrease oil consumption by 50-70 percent. Application of ultrasonic vibration to MQL cutting was found to be effective particularly in decreasing crater wear at slower cutting speeds, which were inevitable in machining a slender bar of smaller diameters. With tools for monitoring cutting temperature precisely, thin film thermocouples were fabricated on the tools using photolithography technology, then were coated with hard and thin TiN film. Cutting temperature in turning was measured with these tools. The flow of oil mist was analyzed for tuning and grooving. In grooving, reduction of oil consumption was related to the localization of the flow of oil mist quantitatively.