Investigation On Cryogenic Machining Of Titanium Alloy TC4

Due to its high specific intensity and specific rigidity,excellent corrosion resistance,good heat resistance,the titanium alloy has become an important structural material in the field of aerospace and modern industrial technology.However,titanium alloys also has disadvantages with low elastic modulus,large cutting force per unit area,small thermal conductivity,high cutting temperature and serious tool wear,which make it difficult to machine,machining quality is also not ideal,so,to improve the problem of difficult machining of titanium alloy has become an important research topic in titanium alloy cutting.As a new type of green machining methods,cryogenic machining with liquid nitrogen can inhibit the cutting zone's temperature and tool wear,improve the machined surface integrity by cryogenic cooling and lubrication of cutting zone,therefore,this paper focuses on the research of cryogenic machining of Ti-6Al-4V alloy,the main contents include:The paper develops a liquid nitrogen flow control device based on valve opening and the other new one based on pressure control,then,the research work compares the advantages and disadvantages between the two by the liquid nitrogen flow control,temperature,pressure and other tests,concludes the liquid nitrogen flow control device based on pressure control with a large flow control range,good insulation,improvement of the purity of liquid nitrogen and easy integration,is relatively best solutions for cryogenic machining equipment.With application of the liquid nitrogen flow control device based on pressure control,the research on the cutting force and surface integrity of the titanium alloy TC4 cryogenic machining is investigated by cylindrical turning and right angle turning using different machining parameters and cooling conditions.It is found that liquid nitrogen cryogenic machining increases the cutting force slightly,improves the roughness of machined surface,strengthens the degree of hardening,and reduces the thickness of hardening layer.The influence of different cutting parameters,cooling conditions on the tool wear and service life are experimentally studied by cylindrical turning.It is found that cryogenic machining shows marked improvement on tool wear and service life.With the cutting speed's increase,the improvement of tool life will be more obvious,which means the cryogenic machining can improve the cutting efficiency of titanium alloy TC4.Finally,the influence of different liquid nitrogen jet flow on tool wear and service life are investigated.