As Ti-6 Al-4 V is a typical hard to machine material,especially in micro drilling aviation parts,chip breaking difficulty is of increasing interest to explore its further development.In this study,Longitudinal-Torsion...As Ti-6 Al-4 V is a typical hard to machine material,especially in micro drilling aviation parts,chip breaking difficulty is of increasing interest to explore its further development.In this study,Longitudinal-Torsional Ultrasonic Assisted Drilling(LTUAD)was employed to machine Ti-6 Al-4 V,and its feasibility was evaluated by comparing with Conventional Drilling(CD).By combining periodical characteristics and vibration models(the separated or the unseparated ultrasonic elliptical vibration),the influence of ultrasonic frequency on the intersection characteristics of trajectories were analyzed.And the intersection characteristics were divided into four categories:even periodicity,odd periodicity,non-odd and even periodicity and composite periodicity,indicating different capability for chip breaking.By applying the longitudinal-torsional compound vibration horn,the micro-hole drilling experiment was carried out on machining center.The chip morphology,the thrust force,and the burr height were discussed.Experimental results showed that the morphology of chips presented as smaller and more fragmentary ones in LTUAD compared with continuous helical conical ones and fold-shaped ones in CD.Compared with CD,the average values of the thrust force in LTUAD reduced by 1.98%to 24.9%.According to the burr around the hole exit in both LTUAD and CD,the height of the latter was greatly affected by the drilling parameters.And the burr around the exit of the hole were distributed rather evenly with smaller extension in LTUAD.Consequently,the LTUAD employed in micro-hole drilling was effective.展开更多
The DD6 nickel-based superalloy exhibits remarkably high temperature properties;therefore,it is employed as a crucial structural material in the aviation industry.Nevertheless,this material is difficult to process.Ult...The DD6 nickel-based superalloy exhibits remarkably high temperature properties;therefore,it is employed as a crucial structural material in the aviation industry.Nevertheless,this material is difficult to process.Ultrasonic-assisted drilling(UAD)combines the characteristics of vibration processing technology and conventional drilling technology,significantly improving the machinability of difficult-to-machine materials.Thus,UAD experiments were performed on micro-hole machining of DD6 superalloy in this study.The effects of amplitude,frequency,spindle speed,and feed rate on thrust force,machining quality,and drill bit wear were studied;thereafter,a comparison was drawn between these effects and those of conventional drilling(CD).The experimental results reveal that the thrust force decreases with an increase in spindle speed or a decrease in feed rate for both UAD and CD.UAD can significantly reduce the thrust force.With the same processing parameters,the greater the amplitude,the greater the reduction of the thrust force.The surface roughness of the hole wall produced by UAD is lower than that of CD.Compared with CD,UAD reduces the burr height,improves machining accuracy,and reduces drill bit wear.展开更多
基金supported by the National Natural Science Foundation of China(No.51875179)。
文摘As Ti-6 Al-4 V is a typical hard to machine material,especially in micro drilling aviation parts,chip breaking difficulty is of increasing interest to explore its further development.In this study,Longitudinal-Torsional Ultrasonic Assisted Drilling(LTUAD)was employed to machine Ti-6 Al-4 V,and its feasibility was evaluated by comparing with Conventional Drilling(CD).By combining periodical characteristics and vibration models(the separated or the unseparated ultrasonic elliptical vibration),the influence of ultrasonic frequency on the intersection characteristics of trajectories were analyzed.And the intersection characteristics were divided into four categories:even periodicity,odd periodicity,non-odd and even periodicity and composite periodicity,indicating different capability for chip breaking.By applying the longitudinal-torsional compound vibration horn,the micro-hole drilling experiment was carried out on machining center.The chip morphology,the thrust force,and the burr height were discussed.Experimental results showed that the morphology of chips presented as smaller and more fragmentary ones in LTUAD compared with continuous helical conical ones and fold-shaped ones in CD.Compared with CD,the average values of the thrust force in LTUAD reduced by 1.98%to 24.9%.According to the burr around the hole exit in both LTUAD and CD,the height of the latter was greatly affected by the drilling parameters.And the burr around the exit of the hole were distributed rather evenly with smaller extension in LTUAD.Consequently,the LTUAD employed in micro-hole drilling was effective.
基金This study was supported by the National Scholastic Athletics Foundation(NSAF)(Grant No.U1830122)the National Natural Science Foundation of China(Grant No.51775443).
文摘The DD6 nickel-based superalloy exhibits remarkably high temperature properties;therefore,it is employed as a crucial structural material in the aviation industry.Nevertheless,this material is difficult to process.Ultrasonic-assisted drilling(UAD)combines the characteristics of vibration processing technology and conventional drilling technology,significantly improving the machinability of difficult-to-machine materials.Thus,UAD experiments were performed on micro-hole machining of DD6 superalloy in this study.The effects of amplitude,frequency,spindle speed,and feed rate on thrust force,machining quality,and drill bit wear were studied;thereafter,a comparison was drawn between these effects and those of conventional drilling(CD).The experimental results reveal that the thrust force decreases with an increase in spindle speed or a decrease in feed rate for both UAD and CD.UAD can significantly reduce the thrust force.With the same processing parameters,the greater the amplitude,the greater the reduction of the thrust force.The surface roughness of the hole wall produced by UAD is lower than that of CD.Compared with CD,UAD reduces the burr height,improves machining accuracy,and reduces drill bit wear.
