Ultrasonic elliptical vibration cutting(UEVC)with clockwise elliptical vibration has made notable achievements in precision machining;however,its critical cutting speed limits its application to low-speed machining ta...Ultrasonic elliptical vibration cutting(UEVC)with clockwise elliptical vibration has made notable achievements in precision machining;however,its critical cutting speed limits its application to low-speed machining tasks.Meanwhile,rotary ultrasonic elliptical machining(RUEM)with clockwise elliptical vibration has been validated as an effective high-speed cutting technology.Unfortunately,conventional RUEM leads to increased surface roughness.To address this issue and enhance machining quality,we propose a novel RUEM method employing an anticlockwise vibration direction,called anticlockwise rotary ultrasonic elliptical machining(ARUEM).The mechanisms of surface formation and subsurface strengthening for ARUEM are analyzed.Experimental validations were performed on Ti-6Al-4V alloy,revealing that ARUEM achieved substantially lower ridge heights and up to a 50%reduction in surface roughness compared to conventional RUEM.Additionally,relative to conventional milling,ARUEM resulted in up to 122.6%thicker plastic deformation layers,53.4%higher surface residual compressive stress,and 19.3%greater surface micro-hardness.This study showcases a promising method for high-performance milling of Ti-6Al-4V,offers new insights into RUEM by examining the influence of vibration direction,and enhances understanding of surface formation and subsurface strengthening in the ARUEM method.展开更多
Imposing compressive residual stress field around a fastening hole serves as a universal method to enhance the hole fatigue strength in the aircraft assembly filed.Ultrasonic Peening Drilling(UPD)is a recently propose...Imposing compressive residual stress field around a fastening hole serves as a universal method to enhance the hole fatigue strength in the aircraft assembly filed.Ultrasonic Peening Drilling(UPD)is a recently proposed hybrid hole making process,which can achieve an integration of strengthening and precision-machining with a one-shot-drilling operation.Due to the ironing effect of tool flank surface,UPD introduces large compressive residual stress filed in hole subsurface.In order to reveal the strengthening mechanism of UPD,the influence of ultrasonic vibration and tool dynamic relief angle on ironing coverage rate and its corresponding effect on surface integrity in UPD were analyzed.The experiments were conducted to verify the influence of ironing effect on surface integrity and fatigue behavior of Ti-6Al-4V hole in UPD.The results indicate that the specimen features smaller surface roughness,higher micro-hardness,plastic deformation degree and circumferential compress residual stress under higher ironing coverage rate.The fatigue life increases with the raise of ironing coverage rate,and the fatigue source site in UPD shifts from surface to subsurface comparing with that without vibration assistance.The results demonstrates that a better strengthening effect can be obtained by reasonably controlling the ironing coverage rate in UPD.展开更多
In this study,to address the low efficiency for conventional ultrasonic-assisted drlling(UAD)of carbon fiber-reinforced plastic and titanium alloy(CFRP/Ti)stacks,feasibility experiments of non-separation UAD,in which ...In this study,to address the low efficiency for conventional ultrasonic-assisted drlling(UAD)of carbon fiber-reinforced plastic and titanium alloy(CFRP/Ti)stacks,feasibility experiments of non-separation UAD,in which continuous cutting between the tool and the workpiece occurs at a high feed rate,are carried out.The experimental results indicate that,compared to conventional separation UAD,the non-separation UAD effectively reduces the cutting forces by 24.2%and 1.9%for CFRP stage and 22.1%and 2.6%for the Ti stage at the feed rates of 50 and 70μm/r,respectively.Furthermore,the non-separation UAD significantly improves hole quality,including higher hole diameter accuracy,lower hole surface roughness,and less hole damage.In addition,the non-separation UAD can decrease adhesive tool wear.This study demonstrates that,compared to conventional drilling(CD),the non-separation UAD can effectively improve drilling quality and tool life while maintaining high efficiency.展开更多
Carbon fiber reinforced plastic(CFRP)has been applied in aeronautics,aerospace,automotive and medical industries due to its superior mechanical properties.However,due to its difficult-to-cut characteristic,various dam...Carbon fiber reinforced plastic(CFRP)has been applied in aeronautics,aerospace,automotive and medical industries due to its superior mechanical properties.However,due to its difficult-to-cut characteristic,various damages in twist drilling and chip removal clog in core drilling could happen,inevitably reducing hole quality and hole-manufacturing efficiency.This paper proposes the wave-motion milling(WMM)method for CFRP hole-manufacturing to improve hole quality.This paper presents a motion path model based on the kinematics of the WMM method.The wave-motion cutting mode in WMM was analyzed first.Then,comparison experiments on WMM and conventional helical milling(CHM)of CFRP were carried out under dry conditions.The results showed that the hole surface quality of the CFRP significantly improved with a decrease of 18.1%–36%of Ra value in WMM compared to CHM.WMM exerted a significantly weaker thrust force than that of CHM with a reduction of 12.0%–24.9%and 3%–7.7%for different axial feed per tooth and tangential feed per tooth,respectively.Meanwhile,the hole exit damages significantly decreased in WMM.The average tear length at the hole exit in WMM was reduced by 3.5%–29.5%and 35.5%–44.7%at different axial feed per tooth and tangential feed per tooth,respectively.Moreover,WMM significantly alleviated tool wear.The experimental results suggest that WMM is an effective and promising strategy for CFRP hole-manufacturing.展开更多
The sandwich transducer structure is comprised of threecomponents along its main axis: the back metal cap, piezoelectricceramic stack and the horn. The purpose of this work is topresent a simplified method, referred a...The sandwich transducer structure is comprised of threecomponents along its main axis: the back metal cap, piezoelectricceramic stack and the horn. The purpose of this work is topresent a simplified method, referred as the equivalent lengthalgorithm, to design the actuator parameters including eachsegment length and the resonance frequency fs. The actuatorlength L and the propagation wavelength λ along its main axissatisfy the standing wave theory. So, define an equivalent lengthcoefficient for each part of the actuator, and then the sandwichstructure is regarded as a single material cylindrical rod withequivalent length L′. According to the standing wave theory, theequivalent length L′ of the actuator can be determined with thegiven resonance frequency fs, or vice versa. The phase length ofeach part of the actuator in the standing wave is optimized freelyin the design procedure. The actual length of each part of theactuator is determined by the equivalent length coefficient.Finally, the resonance frequencies of three given actuators arecalculated with this method. They are compared with thoseobtained through Ansys simulation and those measured by animpedance analyzer. The results show agreement.展开更多
Advanced hole-making process is of great importance to enhance the fatigue performance of Al-Li alloy part in aviation industry.Ultrasonic peening drilling(UPD),in which an ultrasonic transversal vibration is applied ...Advanced hole-making process is of great importance to enhance the fatigue performance of Al-Li alloy part in aviation industry.Ultrasonic peening drilling(UPD),in which an ultrasonic transversal vibration is applied to the cutting tools,is a recently proposed hole-making method that integrates precision-machining and surface strengthening by single-shot operation.In the study,kinematics,material removal mechanism and strengthening mechanism for UPD of Al-Li alloy by helical fluted reamers are analyzed.The effect of transversal vibration on the cutting performance and surface integrity is studied through comparative experiments between UPD and conventional drilling(CD)of Al-Li alloy holes.The experimental results show that UPD exhibits superior cutting performance with a maximum reduction of 52.6%in thrust force and 52.3%in torque,respectively,compared to CD.Moreover,narrower dimensional tolerance is obtained in UPD due to the reduced transversal force and improved machining stability.Additionally,deeper plastic deformation,higher surface microhardness and residual compressive stress of machined holes are obtained by UPD.The electron back-scattered diffraction(EBSD)analysis confirms that deeper machined affect area and grain refinement are realized in UPD.Therefore,the results indicate that UPD is a feasible method for achieving high-precision and strengthened holes for Al-Li alloy.展开更多
Ti6Al4V alloy is critical for thin-walled aerospace components,yet conventional methods for its surface enhancement struggle to balance efficiency and precision.While ultrasonic vibration milling has been demonstrated...Ti6Al4V alloy is critical for thin-walled aerospace components,yet conventional methods for its surface enhancement struggle to balance efficiency and precision.While ultrasonic vibration milling has been demonstrated to improve fatigue performance,its strengthening mechanism requires further investigation.Additionally,its application in fatigue-critical side milling remains underexplored.To address this gap,we introduce the method of ultrasonic peening side milling(UPSM),which integrates elliptical vibration into side milling to achieve simultaneous machining and surface strengthening.Theoretical and finite element analyses are performed to elucidate the mechanisms of residual stress generation and plastic deformation in UPSM and two-pass UPSM(TUPSM).Our experimental results demonstrate that the UPSM method reduces surface defects.At a vibration amplitude of 8µm,UPSM increases the surface residual compressive stress by 47.4%and the thickness of subsurface plastic deformation layer by 91.5%as compared to conventional milling(CM).TUPSM amplifies these effects,achieving a 55.5%increase in residual compressive stress.Fatigue tests reveal 3.38-fold(for UPSM)and 3.76-fold(for TUPSM)improvement in fatigue life over CM,a phenomenon which is attributed to the subsurface crack initiation and grain refinement induced by ultrasonic ironing and impact effects.This work establishes UPSM as an integrated and cost-effective solution for enhancing fatigue performance in thin-walled Ti6Al4V components,overcoming the limitations of conventional methods and advancing between precision machining and strengthening treatments.展开更多
基金supported by the National Natural Science Foundation of China(Nos.91960203 and 52375399)the Chinese Aeronautical Establishment Aeronautical Science Foundation(No.2022Z045051001).
文摘Ultrasonic elliptical vibration cutting(UEVC)with clockwise elliptical vibration has made notable achievements in precision machining;however,its critical cutting speed limits its application to low-speed machining tasks.Meanwhile,rotary ultrasonic elliptical machining(RUEM)with clockwise elliptical vibration has been validated as an effective high-speed cutting technology.Unfortunately,conventional RUEM leads to increased surface roughness.To address this issue and enhance machining quality,we propose a novel RUEM method employing an anticlockwise vibration direction,called anticlockwise rotary ultrasonic elliptical machining(ARUEM).The mechanisms of surface formation and subsurface strengthening for ARUEM are analyzed.Experimental validations were performed on Ti-6Al-4V alloy,revealing that ARUEM achieved substantially lower ridge heights and up to a 50%reduction in surface roughness compared to conventional RUEM.Additionally,relative to conventional milling,ARUEM resulted in up to 122.6%thicker plastic deformation layers,53.4%higher surface residual compressive stress,and 19.3%greater surface micro-hardness.This study showcases a promising method for high-performance milling of Ti-6Al-4V,offers new insights into RUEM by examining the influence of vibration direction,and enhances understanding of surface formation and subsurface strengthening in the ARUEM method.
基金supported by the National Natural Science Foundation of China(Nos.51905024,51975035 and 91960203).
文摘Imposing compressive residual stress field around a fastening hole serves as a universal method to enhance the hole fatigue strength in the aircraft assembly filed.Ultrasonic Peening Drilling(UPD)is a recently proposed hybrid hole making process,which can achieve an integration of strengthening and precision-machining with a one-shot-drilling operation.Due to the ironing effect of tool flank surface,UPD introduces large compressive residual stress filed in hole subsurface.In order to reveal the strengthening mechanism of UPD,the influence of ultrasonic vibration and tool dynamic relief angle on ironing coverage rate and its corresponding effect on surface integrity in UPD were analyzed.The experiments were conducted to verify the influence of ironing effect on surface integrity and fatigue behavior of Ti-6Al-4V hole in UPD.The results indicate that the specimen features smaller surface roughness,higher micro-hardness,plastic deformation degree and circumferential compress residual stress under higher ironing coverage rate.The fatigue life increases with the raise of ironing coverage rate,and the fatigue source site in UPD shifts from surface to subsurface comparing with that without vibration assistance.The results demonstrates that a better strengthening effect can be obtained by reasonably controlling the ironing coverage rate in UPD.
基金supported by the National Natural Science Foundation of China(Nos.52375399 and 91960203)the Aeronautical Science Foundation of China(No.2022Z045051001).
文摘In this study,to address the low efficiency for conventional ultrasonic-assisted drlling(UAD)of carbon fiber-reinforced plastic and titanium alloy(CFRP/Ti)stacks,feasibility experiments of non-separation UAD,in which continuous cutting between the tool and the workpiece occurs at a high feed rate,are carried out.The experimental results indicate that,compared to conventional separation UAD,the non-separation UAD effectively reduces the cutting forces by 24.2%and 1.9%for CFRP stage and 22.1%and 2.6%for the Ti stage at the feed rates of 50 and 70μm/r,respectively.Furthermore,the non-separation UAD significantly improves hole quality,including higher hole diameter accuracy,lower hole surface roughness,and less hole damage.In addition,the non-separation UAD can decrease adhesive tool wear.This study demonstrates that,compared to conventional drilling(CD),the non-separation UAD can effectively improve drilling quality and tool life while maintaining high efficiency.
基金supported by National Natural Science Foundation of China(Grant No.51905024,51905138,51975035 and 91960203).
文摘Carbon fiber reinforced plastic(CFRP)has been applied in aeronautics,aerospace,automotive and medical industries due to its superior mechanical properties.However,due to its difficult-to-cut characteristic,various damages in twist drilling and chip removal clog in core drilling could happen,inevitably reducing hole quality and hole-manufacturing efficiency.This paper proposes the wave-motion milling(WMM)method for CFRP hole-manufacturing to improve hole quality.This paper presents a motion path model based on the kinematics of the WMM method.The wave-motion cutting mode in WMM was analyzed first.Then,comparison experiments on WMM and conventional helical milling(CHM)of CFRP were carried out under dry conditions.The results showed that the hole surface quality of the CFRP significantly improved with a decrease of 18.1%–36%of Ra value in WMM compared to CHM.WMM exerted a significantly weaker thrust force than that of CHM with a reduction of 12.0%–24.9%and 3%–7.7%for different axial feed per tooth and tangential feed per tooth,respectively.Meanwhile,the hole exit damages significantly decreased in WMM.The average tear length at the hole exit in WMM was reduced by 3.5%–29.5%and 35.5%–44.7%at different axial feed per tooth and tangential feed per tooth,respectively.Moreover,WMM significantly alleviated tool wear.The experimental results suggest that WMM is an effective and promising strategy for CFRP hole-manufacturing.
基金supported by National NaturalScience Foundation of China [grant numbers 51475031 and51475029].
文摘The sandwich transducer structure is comprised of threecomponents along its main axis: the back metal cap, piezoelectricceramic stack and the horn. The purpose of this work is topresent a simplified method, referred as the equivalent lengthalgorithm, to design the actuator parameters including eachsegment length and the resonance frequency fs. The actuatorlength L and the propagation wavelength λ along its main axissatisfy the standing wave theory. So, define an equivalent lengthcoefficient for each part of the actuator, and then the sandwichstructure is regarded as a single material cylindrical rod withequivalent length L′. According to the standing wave theory, theequivalent length L′ of the actuator can be determined with thegiven resonance frequency fs, or vice versa. The phase length ofeach part of the actuator in the standing wave is optimized freelyin the design procedure. The actual length of each part of theactuator is determined by the equivalent length coefficient.Finally, the resonance frequencies of three given actuators arecalculated with this method. They are compared with thoseobtained through Ansys simulation and those measured by animpedance analyzer. The results show agreement.
基金Supported by National Natural Science Foundation of China(Nos.52375399,91960203 and 51975035)Chinese Aeronautical Establishment Aeronautical Science Foundation(No.2022Z045051001).
文摘Advanced hole-making process is of great importance to enhance the fatigue performance of Al-Li alloy part in aviation industry.Ultrasonic peening drilling(UPD),in which an ultrasonic transversal vibration is applied to the cutting tools,is a recently proposed hole-making method that integrates precision-machining and surface strengthening by single-shot operation.In the study,kinematics,material removal mechanism and strengthening mechanism for UPD of Al-Li alloy by helical fluted reamers are analyzed.The effect of transversal vibration on the cutting performance and surface integrity is studied through comparative experiments between UPD and conventional drilling(CD)of Al-Li alloy holes.The experimental results show that UPD exhibits superior cutting performance with a maximum reduction of 52.6%in thrust force and 52.3%in torque,respectively,compared to CD.Moreover,narrower dimensional tolerance is obtained in UPD due to the reduced transversal force and improved machining stability.Additionally,deeper plastic deformation,higher surface microhardness and residual compressive stress of machined holes are obtained by UPD.The electron back-scattered diffraction(EBSD)analysis confirms that deeper machined affect area and grain refinement are realized in UPD.Therefore,the results indicate that UPD is a feasible method for achieving high-precision and strengthened holes for Al-Li alloy.
基金supported by the National Natural Science Foundation of China(Nos.91960203 and 52375399)the Natural Science Foundation of Beijing Municipality(No.Z230004),China.
文摘Ti6Al4V alloy is critical for thin-walled aerospace components,yet conventional methods for its surface enhancement struggle to balance efficiency and precision.While ultrasonic vibration milling has been demonstrated to improve fatigue performance,its strengthening mechanism requires further investigation.Additionally,its application in fatigue-critical side milling remains underexplored.To address this gap,we introduce the method of ultrasonic peening side milling(UPSM),which integrates elliptical vibration into side milling to achieve simultaneous machining and surface strengthening.Theoretical and finite element analyses are performed to elucidate the mechanisms of residual stress generation and plastic deformation in UPSM and two-pass UPSM(TUPSM).Our experimental results demonstrate that the UPSM method reduces surface defects.At a vibration amplitude of 8µm,UPSM increases the surface residual compressive stress by 47.4%and the thickness of subsurface plastic deformation layer by 91.5%as compared to conventional milling(CM).TUPSM amplifies these effects,achieving a 55.5%increase in residual compressive stress.Fatigue tests reveal 3.38-fold(for UPSM)and 3.76-fold(for TUPSM)improvement in fatigue life over CM,a phenomenon which is attributed to the subsurface crack initiation and grain refinement induced by ultrasonic ironing and impact effects.This work establishes UPSM as an integrated and cost-effective solution for enhancing fatigue performance in thin-walled Ti6Al4V components,overcoming the limitations of conventional methods and advancing between precision machining and strengthening treatments.
