Experimental Study On Cutting Of Titanium Alloy Using Abrasive Water Jet

The titanium alloy is one kind of materials with excellent features. It has light weight,high hot strength, high specific strength, good corrosion resistance and good mechanicalproperties. Nowadays, It is widely used in aero-space, automobile, chemical industry andcreate a huge economic and social benefits. It plays an important role in the national economyand national defense. However, due to its defects such as low thermal conductivity, lowplastic, low hardness, small elastic modulus, large elastic deformation and so on, theextensive use of the titanium alloy is affected. Because of high production costs, cycle long,and a lot of smoke hazardous to health, it is difficulties to cut using the traditional mechanicalcutting. In a long time, the application of titanium alloy is limited to specific area. To promotegreen and efficient cutting of titanium alloys is a key problem in the application of titanium.Therefore, there is a very important theoretical significance and practical value in the study ofthe titanium alloy cutting.Abrasive water jet （AWJ）, as only a “soft, cold” cutting technology is a newly specialmachining technology to the rapid development in recent decades. AWJ features for its strongcold erosion grinding effect with low heat effect zone, adaptable to the material non-selective,minimum counteraction, no spark, and good incision quality, no pollution, low processingcost, energy concentration and other unique advantages. It can be not only applied in all kindsof metal, nonmetal but also in many cutting conditions such as heat-sensitive materials,pressure-sensitive materials, high hardness, high brittleness materials, difficult to cutmaterials and composite materials and has broad application prospects in machinerymanufacturing, aerospace manufacturing, medical, military, new energy and other areas.Nowdays, it has been widely used in cutting metal, ceramics, stone, laminated glass, coatedcomposites and titanium alloy plate. Compared with other processing methods, It has obviousadvantages for abrasive water jet technology in cutting difficulty to machine materials such asceramics, stone, stainless steel, glass, titanium alloy and so on. It is easily implementedfinishing and generally precise finishing is not needed.Based on waterjet machining technology, the experiments on cutting of titanium alloy,Ti-6Al-4V（TC4） were carried out. The study on the feasibility of cutting titanium alloy usingwaterjet is demonstrated. On the other hand, the experiements on cutting of titanium alloyusing electrical discharge machining （EDM） is also carried out. Macroscopic surface features,cutting parameters on processing capacity and processing quality （surface roughness） werestudied. The physical or chemical changes of work piece as well as the microscopic effects ofabrasives on the workpiece after water jet cutting performance are tested. The researchesshowed that the process of titanium alloy cutting will be optimized by abrasive waterjetmachining. The working temperature is not higher than100℃. Abrasive waterjet cutting has effect on the surface finish. But it can’t destroy the internal structure of work piecesexcept for obvious kerf.Furthermore, orthogonal experimental method and range analysis method are used inoptimizing the process parameters for abrasive water jet cutting titanium alloy. The studyresults showed that when the workpiece thickness as7.53mm, the quality level index as5, thetop cutting surface roughness as measured by the optimal level combination of processparameters is: the jet pressure as210MPa, the nozzle combination as0.25:0.76mm; Whenthe workpiece thickness as13.53mm, the quality level index as5, the bottom cutting surfaceroughness as measured by the optimal level combination of process parameters is: the jetpressure as240MPa, the nozzle combination as0.25:0.76mm. Multiple linear regressionanalysis method, using the Matlab language, are used to establish a prediction model ofabrasive water jet cutting of titanium alloy top and bottom surface roughness （Ra）.The top cutting suface roughness （Ra1） prediction model:R_a1=1.3516×p^0.2999×d_f^0.6371×q^-0.2979×T^-0.2129 The bottom cutting suface roughness （Ra2） prediction model:R_a2=4.5006×p^0.1565×d_f^0.9679×q^-0.5184×T^-0.0708Nine sets of parameters randomly were selected by reflecting the machine cuttingperformance and cutting experiments were made. Then the predicted and actual values wascompared. The results indicated that both the relative errors are not more than10percent. Andthe two prediction models have higher prediction accuracy and generalization ability. Thetheory has a greater reference value for the selection of the abrasive water jet parameters usedfor cutting the TC4workpieces.The results studied in this thesis have significant academic significance and contributedto the application of titanium alloys.