A fast tool servo (FTS) system is developed for the fabrication of non-rotationally symmetric micro-structured surfaces using single-point diamond turning machines.The constructed FTS employs a piezoelectric tube actu...A fast tool servo (FTS) system is developed for the fabrication of non-rotationally symmetric micro-structured surfaces using single-point diamond turning machines.The constructed FTS employs a piezoelectric tube actuator (PZT) to actuate the diamond tool and a capacitive probe as the feedback sensor.To compensate the inherent nonlinear hysteresis behavior of the piezoelectric actuator,Proportional Integral (PI) feedback control is implemented.Besides,a feed-forward control based on a simple feed-forward predictor has been added to achieve better tracking performance.Experimental results indicate that error motions in the performance of the system caused by hysteresis can be reduced greatly and the micro-structured surface is successfully fabricated by implementing the FTS.展开更多
Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room tem...Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room temperature which transfers the FTS fabricated sinusoidal grid surface to the flat film with UV-moulding process was described.A piezoelectric-assisted FTS with high band width of 2 kHz,travel range up to 16 μm and the compact mechanism structure was designed for the sinusoidal grid surface machining and the dynamic performance testing of FTS was described in detail.Machining results indicate that the dimensions of sinusoidal grid change with the variation of the FTS machining condition.Wetting properties of UV-moulded surface were evaluated,the best contact angle was measured to be 120.5° on the sinusoidal grid surface with profile wavelength of 350 μm and peak-to-valley amplitude of about 16 μm.展开更多
Diamond turning based on a fast tool servo(FTS)is widely used in freeform optics fabrication due to its high accuracy and machining efficiency.As a new trend,recently developed high-frequency and long-stroke FTS units...Diamond turning based on a fast tool servo(FTS)is widely used in freeform optics fabrication due to its high accuracy and machining efficiency.As a new trend,recently developed high-frequency and long-stroke FTS units are independently driven by a separate control system from the machine tool controller.However,the tool path generation strategy for the independently controlled FTS is far from complete.This study aims to establish methods for optimizing tool path for the independent control FTS to reduce form errors in a single step of machining.Different from the conventional integrated FTS control system,where control points are distributed in a spiral pattern,in this study,the tool path for the independent FTS controller is generated by the ring method and the mesh method,respectively.The machined surface profile is predicted by simulation and the parameters for the control point generation are optimized by minimizing the deviation between the predicted and the designed surfaces.To demonstrate the feasibility of the proposed tool path generation strategies,cutting tests of a two-dimensional sinewave and a micro-lens array were conducted and the results were compared.As a result,after tool path optimization,the peak-to-valley form error of the machined surface was reduced from 429 nm to 56 nm for the two-dimensional sinewave by using the ring method,and from 191 nm to 103 nm for the micro-lens array by using the mesh method,respectively.展开更多
A lens array is often used for optical components of sensing devices,requiring high surface quality and form accuracy.Fast tool servo(FTS)-based diamond turning is one of the technologies for manufacturing complicated...A lens array is often used for optical components of sensing devices,requiring high surface quality and form accuracy.Fast tool servo(FTS)-based diamond turning is one of the technologies for manufacturing complicated shapes,such as freeform optics,structured surfaces,and microlens arrays,with high machining efficiency.In this study,lens array machining was performed on copper using an FTS on a diamond turning machine.For evaluating the lens array surface topography,the focus was on surface waviness formation.As a dominating factor of surface waviness,the system dynamics behavior was investigated by capturing and analyzing the position signal.It was found that a specific waviness pattern could be formed on the surface due to the servo response.By considering the dynamics of the FTS system from the captured signals,the FTS system behavior was identified,and optimal machining parameters for the lens array were proposed.A machining test under the optimized cutting conditions reduced the average Sdq used to quantify the waviness amount from 93 to 50μrad and the standard deviation from 33 to 3μrad,which greatly improved the consistency in accuracy for all lens arrays.This study will contribute to the appropriate utilization of FTS systems in the ultraprecision machining of various advanced optics,such as microlens arrays.展开更多
Thin-walled components possess high strength and lightweight characteristics;thus,they are widely used in aerospace,automotive,and other industrial felds.However,their low stifness makes them susceptible to deformatio...Thin-walled components possess high strength and lightweight characteristics;thus,they are widely used in aerospace,automotive,and other industrial felds.However,their low stifness makes them susceptible to deformation induced by cutting forces during machining,which leads to poor form accuracy.To address this issue,this paper proposes an in-process deformation estimation and compensation method.Because direct,accurate measurement of the deformation at the cutting point is challenging,the deformation is estimated based on the deformations measured at points in the uncut area along the same axial line as the cutting point.To establish the deformation relationship along the axial line for estimation,fnite element method simulations are conducted to generate axial deformation profles corresponding to diferent cutting force locations.Additionally,a calibration coefcient obtained through experiments is applied to enhance the accuracy of the deformation estimation.Then,the estimated deformation is fed into the control loop of the fast tool servo system to compensate for machining-induced deformation efectively.To validate the efectiveness of the proposed method,machining experiments on sinusoidal pit arrays and sinusoidal grid microstructures are performed.The experimental results demonstrate that the proposed method substantially improves machining accuracy.展开更多
A novel precision vibration-assisted micro-engraving system was developed by the integration of fast tool servo and ultrasonic elliptical vibration system, in which the flexure hinge was designed to avoid backlash and...A novel precision vibration-assisted micro-engraving system was developed by the integration of fast tool servo and ultrasonic elliptical vibration system, in which the flexure hinge was designed to avoid backlash and PID control algorithm was established to guarantee specific precision. Apart from experimental validation of the performance of the system, various micro-V-grooves cutting experiments on aluminum alloy, ferrous material and hard cutting material were performed, in which Kistler force sensor was used to measure cutting force. Through experiments, it was clear that the vibration-assisted micro-engraving system can ensure good quality of micro-V-grooves and reduce cutting force by about 60% compared with traditional removal process without ultrasonic vibration.展开更多
Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical compone...Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical component manufacturing. In this process, first high precision microoptical molds are fabricated using ultraprecision single point diamond machining followed by high volume production methods such as compression or injection molding. In the last two decades, there have been steady improvements in ultraprecision machine design and performance, particularly with the introduction of both slow tool and fast tool servo. Today optical molds, including freeform surfaces and microlens arrays, are routinely diamond machined to final finish without post machining polishing. For consumers, compression mold- ing or injection molding provide efficient and high quality optics at extremely low cost. In this paper, first ultrapreci- sion machine design and machining processes such as slow tool and fast too servo are described then both compression molding and injection molding of polymer optics are discussed. To implement precision optical manufacturing by molding, numerical modeling can be included in the future as a critical part of the manufacturing process to ensure high product quality.展开更多
基金Funded by the National High-tech R&D Program ("863" Program) of China (No.2006AA04Z314)
文摘A fast tool servo (FTS) system is developed for the fabrication of non-rotationally symmetric micro-structured surfaces using single-point diamond turning machines.The constructed FTS employs a piezoelectric tube actuator (PZT) to actuate the diamond tool and a capacitive probe as the feedback sensor.To compensate the inherent nonlinear hysteresis behavior of the piezoelectric actuator,Proportional Integral (PI) feedback control is implemented.Besides,a feed-forward control based on a simple feed-forward predictor has been added to achieve better tracking performance.Experimental results indicate that error motions in the performance of the system caused by hysteresis can be reduced greatly and the micro-structured surface is successfully fabricated by implementing the FTS.
基金supported by NCRC(National Core Research Center)program of the Ministry of Education,Science and Technology(2010-0008-277)"Development of next generation multi-functional machining systems for eco/bio components" project of ministry of knowledge economy
文摘Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room temperature which transfers the FTS fabricated sinusoidal grid surface to the flat film with UV-moulding process was described.A piezoelectric-assisted FTS with high band width of 2 kHz,travel range up to 16 μm and the compact mechanism structure was designed for the sinusoidal grid surface machining and the dynamic performance testing of FTS was described in detail.Machining results indicate that the dimensions of sinusoidal grid change with the variation of the FTS machining condition.Wetting properties of UV-moulded surface were evaluated,the best contact angle was measured to be 120.5° on the sinusoidal grid surface with profile wavelength of 350 μm and peak-to-valley amplitude of about 16 μm.
基金supported by Japan Society for the Promotion of Science,Grant-in-Aid for Scientific Research(B),Project Number 21H01230.
文摘Diamond turning based on a fast tool servo(FTS)is widely used in freeform optics fabrication due to its high accuracy and machining efficiency.As a new trend,recently developed high-frequency and long-stroke FTS units are independently driven by a separate control system from the machine tool controller.However,the tool path generation strategy for the independently controlled FTS is far from complete.This study aims to establish methods for optimizing tool path for the independent control FTS to reduce form errors in a single step of machining.Different from the conventional integrated FTS control system,where control points are distributed in a spiral pattern,in this study,the tool path for the independent FTS controller is generated by the ring method and the mesh method,respectively.The machined surface profile is predicted by simulation and the parameters for the control point generation are optimized by minimizing the deviation between the predicted and the designed surfaces.To demonstrate the feasibility of the proposed tool path generation strategies,cutting tests of a two-dimensional sinewave and a micro-lens array were conducted and the results were compared.As a result,after tool path optimization,the peak-to-valley form error of the machined surface was reduced from 429 nm to 56 nm for the two-dimensional sinewave by using the ring method,and from 191 nm to 103 nm for the micro-lens array by using the mesh method,respectively.
文摘A lens array is often used for optical components of sensing devices,requiring high surface quality and form accuracy.Fast tool servo(FTS)-based diamond turning is one of the technologies for manufacturing complicated shapes,such as freeform optics,structured surfaces,and microlens arrays,with high machining efficiency.In this study,lens array machining was performed on copper using an FTS on a diamond turning machine.For evaluating the lens array surface topography,the focus was on surface waviness formation.As a dominating factor of surface waviness,the system dynamics behavior was investigated by capturing and analyzing the position signal.It was found that a specific waviness pattern could be formed on the surface due to the servo response.By considering the dynamics of the FTS system from the captured signals,the FTS system behavior was identified,and optimal machining parameters for the lens array were proposed.A machining test under the optimized cutting conditions reduced the average Sdq used to quantify the waviness amount from 93 to 50μrad and the standard deviation from 33 to 3μrad,which greatly improved the consistency in accuracy for all lens arrays.This study will contribute to the appropriate utilization of FTS systems in the ultraprecision machining of various advanced optics,such as microlens arrays.
基金supported in part by National Natural Science Foundation of China under Grant 52425505 and U22A20207in part by National Key R&D Program of China under Grant 2022YFB3403302in part by Zhejiang Provincial Key R&D Program of China under Grant 2023C01056.
文摘Thin-walled components possess high strength and lightweight characteristics;thus,they are widely used in aerospace,automotive,and other industrial felds.However,their low stifness makes them susceptible to deformation induced by cutting forces during machining,which leads to poor form accuracy.To address this issue,this paper proposes an in-process deformation estimation and compensation method.Because direct,accurate measurement of the deformation at the cutting point is challenging,the deformation is estimated based on the deformations measured at points in the uncut area along the same axial line as the cutting point.To establish the deformation relationship along the axial line for estimation,fnite element method simulations are conducted to generate axial deformation profles corresponding to diferent cutting force locations.Additionally,a calibration coefcient obtained through experiments is applied to enhance the accuracy of the deformation estimation.Then,the estimated deformation is fed into the control loop of the fast tool servo system to compensate for machining-induced deformation efectively.To validate the efectiveness of the proposed method,machining experiments on sinusoidal pit arrays and sinusoidal grid microstructures are performed.The experimental results demonstrate that the proposed method substantially improves machining accuracy.
基金Supported by National High Technology Research and Development Program of China ("863" Program, No. 2009AA043802)Japan Society for the Promotion of Science
文摘A novel precision vibration-assisted micro-engraving system was developed by the integration of fast tool servo and ultrasonic elliptical vibration system, in which the flexure hinge was designed to avoid backlash and PID control algorithm was established to guarantee specific precision. Apart from experimental validation of the performance of the system, various micro-V-grooves cutting experiments on aluminum alloy, ferrous material and hard cutting material were performed, in which Kistler force sensor was used to measure cutting force. Through experiments, it was clear that the vibration-assisted micro-engraving system can ensure good quality of micro-V-grooves and reduce cutting force by about 60% compared with traditional removal process without ultrasonic vibration.
基金the National High Technology Research and Development Program ("863" program) of China(No.2009AA044305)the National Natural Science Foundation of China(Nos.90923320 and 90923038)the "111" Project by the State Administration of Foreign Experts Affairs and the Ministry of Education of China(No.B07014)~~
文摘Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical component manufacturing. In this process, first high precision microoptical molds are fabricated using ultraprecision single point diamond machining followed by high volume production methods such as compression or injection molding. In the last two decades, there have been steady improvements in ultraprecision machine design and performance, particularly with the introduction of both slow tool and fast tool servo. Today optical molds, including freeform surfaces and microlens arrays, are routinely diamond machined to final finish without post machining polishing. For consumers, compression mold- ing or injection molding provide efficient and high quality optics at extremely low cost. In this paper, first ultrapreci- sion machine design and machining processes such as slow tool and fast too servo are described then both compression molding and injection molding of polymer optics are discussed. To implement precision optical manufacturing by molding, numerical modeling can be included in the future as a critical part of the manufacturing process to ensure high product quality.
