Study On Turning Machining Of The Damage-tolerant Titanium Alloy-TC21

With the rapid development of aerospace and other advanced manufacturing industry in our country, the titanium alloy has been widely usedwith the excellent performance. However, these materials always belong to difficult processing materials for processing. damage-tolerant titanium alloy-TC21 in view of the application and development of aviation aircraft,with high fracture toughness, high strength, low crack growth rate,has been more and more widely used in the field of aerospace.In this context, this paper’swork focus on cutting TC21 bar stock include of cutting parameters, tool wear and surface integrity of the content..Turning processing is the important part of mechanical processing, and appropriate selecting of the cutting parameters with the balance of efficiency and quality has important significance. With the aim of cutter knife after VB value and processed workpiece surface roughness as the criterion, the single factor experiment and orthogonal experiment was carried out respectively to optimize cutting parameters. The results show that feed speed for the influence of roughness is the largest, the influence of cutting speed on tool wear is the largest, large cutting depth can improve the efficiency of cutting but after toolarge cutting depth can cause crack resulting in sudden collapse knife impact tool processing quality. In using hard alloy cutter with Ti Al N coating to cut φ=40 bar,when the spindle speed n = 250 r/min, feed speed Vf/r = 0.1 mm(feed), the cutting depth ap = 0.2 mm, can obtain better surface roughness can accept the amount of tool wear, at the same time guarantee of efficiency.TC21 is a kind of hard processing material, which mainly problem is the knives’ service life and low, poor stability, so the accurate analysis and evaluation of the cutting tool is a very important work.Through analysising microscopic wear mechanism of cutter for experiments to explore, only useing tool microscope measurement VB value is not comprehensive reaction of tool wear condition. Through the experiment of tool wear morphology and energy spectrum analysis confirmed the adhesion wear is the main wear mechanism of cutting tool rake face and the cutter blade surface after mainly abrasive wear mode.Finally, the paper pay attention to to select suitable surface integrity feature parameters for accurate evaluation of the parts processing quality problem.By turning test pieces of the surface integrity and fatigue strength of research, probes into the effects of surface integrity on fatigue strength.after analysis the microhardness, residual stress, surface roughness, and other characterization parameters, finally found that the effects of surface roughness on fatigue strength is the largest, and by use of polishing technology can effectively improve the fatigue strength of test pieces.