| This paper uses a combination method of theoretical analysis and cutting test to systematically study the surface integrity of?-Ti Al alloy milling,analyzes the change rule and mechanism of 3D surface morphology,micro-hardness and surface defects under different cutting parameters,study the change rule of cutting force and chip morphology with cutting parameters,and establishes critical state model based on brittle-plastic transition.The effect of cutting parameters on surface roughness,three-dimensional topography,micro-hardness,surface defects,and cutting forces was studied through a single-factor test of milling?-Ti Al alloy.By comprehensively considering tool life,processing quality and efficiency to determine the cutting parameter range of?-Ti Al alloy milling:(1)v_c=40?120m/min?a_p=0.05?0.2mm and f_z=0.005?0.02mm/z during finishing(0.093?m?R_a?0.32?m);(2)a_p<0.05mm?f_z<0.005mmm/z and v_c=40?120m/min during super finishing(0.006?m?R_a?0.117?m).Theoretical and experimental research on plastic milling of?-Ti Al alloy is carried out.Establish a geometric model for plastic processing of?-Ti Al alloy based on the material characteristics of?-Ti Al alloy.Determined by bevel cutting test,the critical parameters for the milling of?-Ti Al alloy in the plastic region are v_c=120m/min?f_z=0.01?0.025mm/z and a_p=0.05?0.1mm,and it is verified that the high-quality processed surface can be obtained in the plastic field milling,and the minimum surface roughness value can be achieved as R_a=0.149?m.The effect of cutting parameters on the roughness of the machined surface was studied through a full-factor test of milling?-Ti Al alloy.Studies have shown that the important effect factors that affect the surface roughness of?-Ti Al alloy milling are cutting speed and feed rate,followed by cutting speed.However,the effect of the two-to-two interaction between the cutting speed,the back-feed amount and the feed amount per tooth on the surface roughness is not significant.The surface roughness value increases with the increase in the number of cutting tools and the feed per tooth,and increases with the cutting speed and then decreases.A mathematical prediction model of surface roughness based on cutting parameters was established by using a partial least squares regression model.The correlation analysis of the model and F-test showed that the model had good accuracy and could meet the general prediction requirements of surface roughness.Based on the above experimental data,according to two different optimization goals of"optimal quality"and"optimal productivity",the cutting parameters in the milling process of?-Ti Al alloy were optimized.The research showed that the"optimal quality"cutting parameter combination are v_c=120m/min,f_z=0.005mm/z and a_p=0.05mm,the surface roughness and cutting force at this time are R_a=0.227?m and F=11.484N,respectively.The"best productivity"cutting parameter combination are v_c=120m/min,f_z=0.0097mm/z,and a_p=0.086 mm.At this time,the surface roughness,cutting force and material removal rate(MRR)are R_a=0.2973?m,F=14.858N and MRR=0.4001cm~3/min.Finally,the model was verified and analyzed,and it was found that the surface roughness and cutting force error range was below20%,and the model was more accurate. |
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