Cutting Properties Analysis of Titanium Alloy (Ti-6Al-4V) Base on Cryogenic Cooling

This paper studied the cutting properties of Ti-6Al-4V under cryogenic cooling to find a solution of improvement in tool load-carrying, thermal stress, tool life and finish quality. Firstly, this paper established a 3-D cutting model of Ti-6Al-4V under cryogenic cooling with liquid nitrogen, and then set the parameters of material, friction model and cutting conditions. Based on this model, the results of chips' shape, cutting forces and temperature distribution were obtained in the simulation with different cooling approaches. The results reveal that the cryogenic cooling with liquid nitrogen can slightly increase the main cutting force but it canefficiently cool the cutting area, and the cooling will contribute to the deformation of chips and improving the finish quality. Titanium alloy is widely applied in modern advanced equipment manufacturing industry because of its superior comprehensive performance, especially the aerospace field. But with the features of small thermal conductivity, low modulus of elasticity, strong chemical activity, and easily reacting with surrounding medium under the cutting temperatures, which reduce the cutting performance of titanium alloy greatly, and limiting its applications in many important areas. Now turning is still the most important methods in titanium alloy processing, where many scholars have engaged researches, most of the work focused on the following three aspects: the cutting tool material, cutting parameter optimization and cooling approaches. Researches have showed that the control of cutting temperature is the key to prolong tool life, improve the machining efficiency and quality. High pressure and large flow cutting fluid is commonly used in early titanium alloy's cutting to reduce the temperature of cutting area, inhibit the high temperature chemical activity of titanium alloy, and thus prolong tool life. With the deepening of the research, people found that by reason of titanium alloys poor thermal conductivity and small cutting contact area, it is easy to bring about stress and thermal concentration, additionally, the penetration ability of traditional cutting fluid is poor, thus, traditional cooling cannot meet the production requirements with the increase of cutting speed. In recent years, with the introduce of the concept of green manufacturing, many scholars who committed to strong air cooling cutting, low temperature freezing cutting, liquid nitrogen (LN2) cooling cutting, MQL (Minimal Quantity Lubrication)and other new type of cooling method research, have achieved positive results. The LN2 cooling with its good cooling and lubricating effect and environmental-friendly character has attracted many attentions from researchers.