The in-situ TiB2 particle reinforced aluminum matrix composites are materials that are difficult to machine,owing to hard ceramic particles in the matrix.In the milling process,the polycrystalline diamond(PCD)tools ar...The in-situ TiB2 particle reinforced aluminum matrix composites are materials that are difficult to machine,owing to hard ceramic particles in the matrix.In the milling process,the polycrystalline diamond(PCD)tools are used for machining these materials instead of carbide cutting tools,which significantly increase the machining cost.In this study,ultrasonic vibration method was applied for milling in-situ TiB2/7050A1 metal matrix composites using a TiAIN coated carbide end milling tool.To completely understand the tool wear mechanism in ultrasonic-vibration assisted milling(UAM),the relative motion of the cutting tool and interaction of workpiecetool-chip contact interface was analyzed in detail.Additionally,a comparative experimental study with and without ultrasonic vibration was carried out to investigate the infuences of ultrasonic vibration and cutting parameters on the cutting force,tool life and tool wear mechanism.The results show that the motion of the cutting tool relative to the chip changes periodically in the helical direction and the separation of tool and chip occurs in the transverse direction in one vibration period,in ultrasonic vibration assisted cutting.I arge instantaneous acceleration can be obtained in axial ultrasonic vibration milling.The cutting force in axial direction is significantly reduced by 42%-57%,40%--57%and 44%-54%,at different cutting speeds,feed rates and cutting depths,respectively,compared with that in conventional milling.Additionally,the tool life is prolonged approximately 2--5 times when the ultrasonic vibration method is applied.The tool wear pattern microcracks are only found in UAM.These might be of great importance for future research in order to understand the cutting mechanisms in UAM of in-situ TiB2/7050A1 metal matrix composites.展开更多
As a typical refractory material,the DD6 nickelbased single-crystal superalloy has important applications in the aviation industry.Ultrasonic-assisted drilling is an advanced machining method that significantly improv...As a typical refractory material,the DD6 nickelbased single-crystal superalloy has important applications in the aviation industry.Ultrasonic-assisted drilling is an advanced machining method that significantly improves machining of refractory materials.The drilling thrust force influences the hole surface quality,burr height,and bit wear.Therefore,it is necessary to predict the thrust force during ultrasonic-assisted drilling.However,there are few reports on the modeling of the thrust force in the ultrasonicassisted drilling of micro-holes.A thrust force prediction model for ultrasonic-assisted micro-drilling is proposed in this study.Based on the basic cutting principle,the dynamic cutting speed,dynamic cutting thickness,and acoustic softening effect caused by ultrasonic vibrations are factored into this model.Through model calibration,the specific friction force and specific normal force coefficients were determined.The model was verified through ultrasonic-assisted drilling experiments conducted at different feed rates,spindle speeds,frequencies,and amplitudes.The maximum and minimum errors of the average thrust force were 10.5%and 2.3%,respectively.This model accurately predicts the thrust force based on the parameters used for ultrasonic-assisted micro-hole drilling and can assist in the analysis and modeling of DD6 superalloy processing.展开更多
基金sponsored by the National Natural Science Foundation of China(Grant No.51775443)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(Grant No.CX201829)the National Science and Technology Major Project(Grant No.2017-Ⅶ-0015-0111).
文摘The in-situ TiB2 particle reinforced aluminum matrix composites are materials that are difficult to machine,owing to hard ceramic particles in the matrix.In the milling process,the polycrystalline diamond(PCD)tools are used for machining these materials instead of carbide cutting tools,which significantly increase the machining cost.In this study,ultrasonic vibration method was applied for milling in-situ TiB2/7050A1 metal matrix composites using a TiAIN coated carbide end milling tool.To completely understand the tool wear mechanism in ultrasonic-vibration assisted milling(UAM),the relative motion of the cutting tool and interaction of workpiecetool-chip contact interface was analyzed in detail.Additionally,a comparative experimental study with and without ultrasonic vibration was carried out to investigate the infuences of ultrasonic vibration and cutting parameters on the cutting force,tool life and tool wear mechanism.The results show that the motion of the cutting tool relative to the chip changes periodically in the helical direction and the separation of tool and chip occurs in the transverse direction in one vibration period,in ultrasonic vibration assisted cutting.I arge instantaneous acceleration can be obtained in axial ultrasonic vibration milling.The cutting force in axial direction is significantly reduced by 42%-57%,40%--57%and 44%-54%,at different cutting speeds,feed rates and cutting depths,respectively,compared with that in conventional milling.Additionally,the tool life is prolonged approximately 2--5 times when the ultrasonic vibration method is applied.The tool wear pattern microcracks are only found in UAM.These might be of great importance for future research in order to understand the cutting mechanisms in UAM of in-situ TiB2/7050A1 metal matrix composites.
基金Project supported by the Major Science and Technology Special Agricultural Projects in Zhejiang Province(No.2007C12064)the Zhejiang Province Breeding New Flower Varieties Major Science and Technology Key Projects(No.2012C12909-10),China。
基金This work was sponsored by the National Natural Science Foundation of China(Grant No.51775443)the National Science and Technology Major Project(Grant No.2017-VII-0015-O111)China Postdoctoral Science Foundation(Grant No.2020M683569).
文摘As a typical refractory material,the DD6 nickelbased single-crystal superalloy has important applications in the aviation industry.Ultrasonic-assisted drilling is an advanced machining method that significantly improves machining of refractory materials.The drilling thrust force influences the hole surface quality,burr height,and bit wear.Therefore,it is necessary to predict the thrust force during ultrasonic-assisted drilling.However,there are few reports on the modeling of the thrust force in the ultrasonicassisted drilling of micro-holes.A thrust force prediction model for ultrasonic-assisted micro-drilling is proposed in this study.Based on the basic cutting principle,the dynamic cutting speed,dynamic cutting thickness,and acoustic softening effect caused by ultrasonic vibrations are factored into this model.Through model calibration,the specific friction force and specific normal force coefficients were determined.The model was verified through ultrasonic-assisted drilling experiments conducted at different feed rates,spindle speeds,frequencies,and amplitudes.The maximum and minimum errors of the average thrust force were 10.5%and 2.3%,respectively.This model accurately predicts the thrust force based on the parameters used for ultrasonic-assisted micro-hole drilling and can assist in the analysis and modeling of DD6 superalloy processing.
