Ultra-precision machine tool is the most important physical tool to machining the workpiece with the frequency domain error requirement, in the design process of which the dynamic accuracy design(DAD) is indispensable...Ultra-precision machine tool is the most important physical tool to machining the workpiece with the frequency domain error requirement, in the design process of which the dynamic accuracy design(DAD) is indispensable and the related research is rarely available. In light of above reasons, a DAD method of ultra-precision machine tool is proposed in this paper, which is based on the frequency domain error allocation.The basic procedure and enabling knowledge of the DAD method is introduced. The application case of DAD method in the ultra-precision flycutting machine tool for KDP crystal machining is described to show the procedure detailedly. In this case, the KDP workpiece surface has the requirements in four different spatial frequency bands, and the emphasis for this study is put on the middle-frequency band with the PSD specifications. The results of the application case basically show the feasibility of the proposed DAD method. The DAD method of ultra-precision machine tool can effectively minimize the technical risk and improve the machining reliability of the designed machine tool. This paper will play an important role in the design and manufacture of new ultra-precision machine tool.展开更多
The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the ...The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the transfer matrix method for multibody systems.In particular,the large-span scale flow field mesh model was created;and the variation in linear and angular stiffness of journal and thrust bearings with respect to film thickness was investigated by adopting the dynamic mesh technique.The dynamic model was proven to be valid by comparing the dynamic characteristics of the machine tool obtained by numerical simulation with the experimental results.In addition,the power spectrum density estimation method was adopted to simulate the statistical ambient vibration excitation by processing the ambient vibration signal measured over a long period of time.Applying it to the dynamic model,the dynamic response of the tool tip under ambient vibration was investigated.The results elucidated that the tool tip response was significantly affected by ambient vibration,and the isolation foundation had a good effect on vibration isolation.展开更多
In order to minimize vibration and improve rotary precision of spindle, we apply active vibration control technique to ultra-precision turning machine based on the analysis of vibration characteristic of aerostatic be...In order to minimize vibration and improve rotary precision of spindle, we apply active vibration control technique to ultra-precision turning machine based on the analysis of vibration characteristic of aerostatic bearing spindle. Using aerostatic bearing itself as actuator, the vibration of spindle is controlled by adjusting admission pressure respectively and by changing pressure distribution in the bearing. The experiments and simulations prove that this method can minimize the vibration of spindle effectively.展开更多
A new idea for designing wheel patterns is presented so as to solve theproblems about machining accuracy of workpiece and wear of honing wheel in ultra-precision planehoning. The influence factors on motion principle ...A new idea for designing wheel patterns is presented so as to solve theproblems about machining accuracy of workpiece and wear of honing wheel in ultra-precision planehoning. The influence factors on motion principle and pattern structures are analyzed andoptimization machining parameters are obtained. By calculating effective cutting length on thesurface of workpiece cut by wheel's abrasive and the orbit of one point on the surface of workpiececontacting with wheel, the wear coefficient of different kinds of wheels and accuracy coefficient ofworkpiece machined by corresponding wheels are obtained. Furthermore, the simulation results showthat the optimal pattern structure of wheel turns out to have lower wheel wear and higher machiningaccuracy.展开更多
In this paper, the modified slip/fracture activation model has been used in order to understand the mechanism of ductile-brittle transition on the R-plane of sapphire during ultra-precision machining by reflecting dir...In this paper, the modified slip/fracture activation model has been used in order to understand the mechanism of ductile-brittle transition on the R-plane of sapphire during ultra-precision machining by reflecting direction of resultant force. Anisotropic characteristics of crack morphology and ductility of machining depending on cutting direction were explained in detail with modified fracture cleavage and plastic deformation parameters. Through the analysis, it was concluded that crack morphologies were mainly determined by the interaction of multiple fracture systems activated while, critical depth of cut was determined by the dominant plastic deformation parameter. In addition to this, by using proportionality relationship between magnitude of resultant force and depth of cut in the ductile region, an empirical model for critical depth of cut was developed.展开更多
There have been various theoretical attempts by researchers worldwide to link up different scales of plasticity studies from the nano-, micro- and macro-scale of observation, based on molecular dynamics, crystal plast...There have been various theoretical attempts by researchers worldwide to link up different scales of plasticity studies from the nano-, micro- and macro-scale of observation, based on molecular dynamics, crystal plasticity and continuum mechanics. Very few attempts, however, have been reported in ultra-precision machining studies. A mesoplasticity approach advocated by Lee and Yang is adopted by the authors and is successfully applied to studies of the micro-cutting mechanisms in ultra-precision machining. Traditionally, the shear angle in metal cutting, as well as the cutting force variation, can only be determined from cutting tests. In the pioneering work of the authors, the use of mesoplasticity theory enables prediction of the fluctuation of the shear angle and micro-cutting force, shear band formation, chip morphology in diamond turning and size effect in nano-indentation. These findings are verified by experiments. The mesoplasticity formulation opens up a new direction of studies to enable how the plastic behaviour of materials and their constitutive representations in deformation processing, such as machining can be predicted, assessed and deduced from the basic properties of the materials measurable at the microscale.展开更多
During ultra-precision machining, machining accuracy is determined by many factors and interaction of these factors. Error sources are systematically analyzed for ultra-precision machine tools, and the influencing deg...During ultra-precision machining, machining accuracy is determined by many factors and interaction of these factors. Error sources are systematically analyzed for ultra-precision machine tools, and the influencing degree of each factor is presented to provide orientation for error reduction and error compensation.展开更多
Digital manufacturing technology can be used in optical field to solve many problems caused by traditional machining. According to the characters of digital manufacturing and the practical applications of ultra-precis...Digital manufacturing technology can be used in optical field to solve many problems caused by traditional machining. According to the characters of digital manufacturing and the practical applications of ultra-precision machining,the process of digital ultra-precision machining and its technical contents were presented in this paper. In the conclusions,it was stated that the digitalization of ultra-precision machining will be an economical and efficient way for the production of new sorts of optical workpieces.展开更多
This paper presents a terahertz(THz)band-pass filter using ultra-precision machining technology based on Chebyshev filter prototype.This iris inductive window coupled waveguide filter was designed by using 8 resonan...This paper presents a terahertz(THz)band-pass filter using ultra-precision machining technology based on Chebyshev filter prototype.This iris inductive window coupled waveguide filter was designed by using 8 resonant cavities with a center frequency of 345 GHz and a 7% bandwidth.The final design fulfills the desired specifications and presents the minimum insertion loss of 1.55 d B and the return loss of less than 15 d B at 345 GHz.The stop-band rejection is50 d B off the center frequency about 30 GHz,which means it has a good performance of high stop-band suppression.Compared with the recent development of THz filters,this filter possesses the characteristic of simple structure and is easy to machining.展开更多
Free abrasive particle machining in simple machine such as: honing, polishing can get higher surface finish mirror, but surface error, and working procedure is hard to control. Therefore, the vertical disposed ultra-p...Free abrasive particle machining in simple machine such as: honing, polishing can get higher surface finish mirror, but surface error, and working procedure is hard to control. Therefore, the vertical disposed ultra-precision plane honing method by ultra-particle diamond honing wheel is put forward to. The results of experiments indicate: plane-honing wheel has higher machining accuracy and machining efficiency. But at the same time the structure parameters of honing wheel effects on machining accuracy. By analyzing the relation of honing wheel structure parameters and workpiece machining accuracy, the relation of honing wheel and wear coefficient, then this paper gets honing wheel structure parameters in the condition of best accuracy coefficient and wear coefficient, and resolve the problem of choosing honing wheel structure parameters in ultra-precision plane honing at last. This paper analyses the relation of honing wheel structure parameters and workpiece machining accuracy coefficient and wear coefficient, by building relative movement math model of honing wheel and workpiece in plane honing. Through theory calculating, the result indicate: about honing machine tools for large volume manufacture, honing wheel wear is main effect factor, so honing wheel should adopt obverse triangle radial structure. About honing machining for high accuracy and low-batch quantities, machining accuracy coefficient is main factors; so honing wheel should adopt reverse triangle radial structure. Neglected the manufacturing factors of honing wheel, then we can design honing wheel with high power curve structure to meet the need of machining accuracy coefficient and honing wheel wear coefficient in higher accuracy honing.展开更多
With the increasing market demand for optical complex surface parts,the application of multi-axis ultraprecision single-point diamond turning is increasing.A tool path generation method is very important to decrease m...With the increasing market demand for optical complex surface parts,the application of multi-axis ultraprecision single-point diamond turning is increasing.A tool path generation method is very important to decrease manufacturing time,enhance surface quality,and reduce cost.Compared with the tool path generation of the traditional multi-axis milling,that of the ultra-precision single-point diamond turning requires higher calculation accuracy and efficiency.This paper reviews the tool path generation of ultra-precision diamond turning,considering several key issues:cutter location(CL)points calculation,the topological form of tool path,interpolation mode,and G code optimization.展开更多
The surface finish quality is critical to the service performance of a machined part,and single-point diamond ultra-precision machining can achieve excellent surface quality for many engineering materials.This study s...The surface finish quality is critical to the service performance of a machined part,and single-point diamond ultra-precision machining can achieve excellent surface quality for many engineering materials.This study studied the problem of predicting the surface roughness for titanium alloy workpieces in ultra-precision machining.Process data and surface roughness measurement results were obtained during end-face machining experiments.A deep learning neural network model was built based on the ResNet-50 architecture to predict surface roughness.We propose increasing prediction accuracy by using the energy ratio difference(ERD)as a stability feature that can be extracted using fast iterative variational mode decomposition(FI-VMD).The roughness value obtained with an analytic model was also used as an input feature of the prediction model.The prediction accuracy of the proposed approach was depicted to be improved by 8.7%with the two newly introduced roughness predictors.The influence of the tool parameters on the prediction accuracy was investigated,and the proposed hybrid-driven model exhibited higher robustness to errors of the tool parameters than the analytic roughness model.展开更多
The tool state exerts a strong influence on surface quality and profile accuracy during precision/ultraprecision machining.However,current on-machine measurement methods cannot precisely obtain the tool nose radius an...The tool state exerts a strong influence on surface quality and profile accuracy during precision/ultraprecision machining.However,current on-machine measurement methods cannot precisely obtain the tool nose radius and wear.This study therefore investigated the onmachine measurement of tool nose radius on the order of hundreds of microns and wear on the order of a few microns to tens of microns during precision/ultra-precision machining using the edge reversal method.To provide the necessary replication,pure aluminum and pure copper soft metal substrates were evaluated,with pure copper exhibiting superior performance.The feasibility of the measurement method was then demonstrated by evaluating the replication accuracy using a 3D surface topography instrument;the measurement error was only 0.1%.The wear of the cutting tool was measured using the proposed method to obtain the maximum values for tool arc wear,flank wear,and wear depth of 3.4 lm,73.5 lm and 3.7 lm,respectively.展开更多
Hard and brittle materials, such as silicon, SiC, and optical glasses, are widely used in aerospace, military, integrated circuit, and other fields because of their excellent physical and chemical properties. However,...Hard and brittle materials, such as silicon, SiC, and optical glasses, are widely used in aerospace, military, integrated circuit, and other fields because of their excellent physical and chemical properties. However, these materials display poor machinability because of their hard and brittle properties. Damages such as surface micro-crack and subsurface damage often occur during machining of hard and brittle materials. Ultra-precision machining is widely used in processing hard and brittle materials to obtain nanoscale machining quality. However, the theoretical mechanism underlying this method remains unclear. This paper provides a review of present research on the molecular dynamics simulation of ultra-precision machining of hard and brittle materials. The future trends in this field are also discussed.展开更多
The nickel-based superalloy Inconel 718 is treated with Coupled Ultrasonic and Electric Pulse Treatment(CUEPT),and the surface grain is refined from the average size of 9550.0 nm to287.9,216.3,150.5,126.3,25.8 nm by d...The nickel-based superalloy Inconel 718 is treated with Coupled Ultrasonic and Electric Pulse Treatment(CUEPT),and the surface grain is refined from the average size of 9550.0 nm to287.9,216.3,150.5,126.3,25.8 nm by different effective treatment currents,respectively.The ultraprecision turning experiments are carried out on the processed workpiece after CUEPT.The experimental results show that the average cutting force increases with the decrease of surface grain size.Moreover,a mathematical model that can describe the relationship between grain size and cutting force is established,and the calculated results match the experimental results well.The calculated results also indicate that the variation of cutting force caused by the same variation of grain size decreases as the degree of grain refinement increases.Finally,the influence mechanism of grain refinement on cutting force is analyzed.The improvement of stability of grain boundaries and the increase of number of grain boundaries cause the increase of cutting force after grain refinement.展开更多
Freeform optics has become the most prominent element of the optics industry. Advanced freeform optical designs supplementary to ultra-precision manufacturing and metrology techniques have upgraded the lifestyle, thin...Freeform optics has become the most prominent element of the optics industry. Advanced freeform optical designs supplementary to ultra-precision manufacturing and metrology techniques have upgraded the lifestyle, thinking, and observing power of existing humans.Imaginations related to space explorations, portability, accessibility have also witnessed sensible in today’s time with freeform optics. Present-day design methods and fabrications techniques applicable in the development of freeform optics and the market requirements are focussed and explained with the help of traditional and non-traditional optical applications. Over the years,significant research is performed in the emerging field of freeform optics, but no standards are established yet in terms of tolerances and definitions. We critically review the optical design methods for freeform optics considering the image forming and non-image forming applications. Numerous subtractive manufacturing technologies including figure correction methods and metrology have been developed to fabricate extreme modern freeform optics to satisfy the demands of various applications such as space, astronomy, earth science, defence,biomedical, material processing, surveillance, and many more. We described a variety of advanced technologies in manufacturing and metrology for novel freeform optics. Next, we also covered the manufacturing-oriented design scheme for advanced optics. We conclude this review with an outlook on the future of freeform optics design, manufacturing and metrology.展开更多
Active vibration control is widely used in both defence and civil industries and therefore, its principle and design are discussed, and acceleration, velocity and displacement of the mass are used as the input variabl...Active vibration control is widely used in both defence and civil industries and therefore, its principle and design are discussed, and acceleration, velocity and displacement of the mass are used as the input variables for the controller. In practice, the time delay of mechanical system should be taken into consideration. An experiment has been successfully made with a HCM-I ultra-precision turning machine. Experimental results indicate that active vibration control can effectively isolate the vibration from the base, and the vibration transmissibility from base to the machine is distinct descend.展开更多
The majority of nanopositioning and nanomeasuring machines(NPMMs)are based on three independent linear movements in a Cartesian coordinate system.This in combination with the specific nature of sensors and tools limit...The majority of nanopositioning and nanomeasuring machines(NPMMs)are based on three independent linear movements in a Cartesian coordinate system.This in combination with the specific nature of sensors and tools limits the addressable part geometries.An enhancement of an NPMM is introduced by the implementation of rotational movements while keeping the precision in the nanometer range.For this purpose,a parameter-based dynamic evaluation system with quantifiable technological parameters has been set up and employed to identify and assess general solution concepts and adequate substructures.Evaluations taken show high potential for three linear movements of the object in combination with two angular movements of the tool.The influence of the additional rotation systems on the existing structure of NPMMs has been investigated further on.Test series on the repeatability of an NPMM enhanced by a chosen combination of a rotary stage and a goniometer setup are realized.As a result of these test series,the necessity of in situ position determination of the tool became very clear.The tool position is measured in situ in relation to a hemispherical reference mirror by three Fabry-Perot interferometers.FEA optimization has been used to enhance the overall system structure with regard to reproducibility and long-term stability.Results have been experimentally investigated by use of a retroreflector as a tool and the various laser interferometers of the NPMM.The knowledge gained has been formed into general rules for the verification and optimization of design solutions for multiaxial nanopositioning machines.展开更多
Aiming at the problem of difficult contact finishing for mini structural surface in course of mould manufacturing,a new no-tool precision machining method based on soft abrasive flow machining (SAFM) was proposed. It ...Aiming at the problem of difficult contact finishing for mini structural surface in course of mould manufacturing,a new no-tool precision machining method based on soft abrasive flow machining (SAFM) was proposed. It allocated restrained component near surface machined,constituted restrained abrasive flow passage,and made the surface become a segment of passage wall. It could control turbulence abrasive flow in restrained passage,realize micro cutting for passage wall,and utilize the irregular motion of abrasive flow to eliminate the mono-directional marks on machined surfaces,and the precision could reach the specular level. A two-phase dynamic model of abrasive flow oriented to SAFM combined with discrete phase model (DPM) was established,the law of two-phase flow motion and the related physical parameters was obtained by corresponding numerical simulation method,and the mechanism of precision machining in SAFM was discussed. Simulation results show that the abrasive flow machining process mainly appears as translation of ablating location with the influence by granular pressure,and as the variation of machining efficiency with the influence by near-wall particle velocity. Thus via control of the inlet velocity and its corresponding machining time,it is supposed to work out the machining process according to the machining requirements by using the Preston equation to seek the relationship among velocity,pressure and material removing rate. By tracking near-wall particles,it can be confirmed that the movement of near-wall abrasive particles is similar to stream-wise vortices. The cutting traces on workpiece surfaces assume disorderly arrangement,so the feasibility of the SAFM method can be reaffirmed.展开更多
Cutting behavior exerts a considerable influence on the fabrication of bulk metallic glass(BMG) components. In this study,the influences of machining parameters(i.e.,depth of cutting,feed rate,and spindle rate) on the...Cutting behavior exerts a considerable influence on the fabrication of bulk metallic glass(BMG) components. In this study,the influences of machining parameters(i.e.,depth of cutting,feed rate,and spindle rate) on the turned surface of a Zr-based BMG after observing the 3D morphologies of this surface were characterized.The results showed that the influence of the spindle rate on the surface morphologies is more substantial as compared to the depth of cutting and the feed rate. Nanoscratch tests were conducted to further characterize the separation mechanism of the chips,which revealed that the chips are torn off the surface of a BMG because of inhomogeneous localized maximum shear stress.展开更多
基金Supported by Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ16E050012)National Natural Science Foundation of China(Grant Nos.51705462 and 51275115)International Science and Technology Cooperation Program of China(Grant No.2015DFA70630)
文摘Ultra-precision machine tool is the most important physical tool to machining the workpiece with the frequency domain error requirement, in the design process of which the dynamic accuracy design(DAD) is indispensable and the related research is rarely available. In light of above reasons, a DAD method of ultra-precision machine tool is proposed in this paper, which is based on the frequency domain error allocation.The basic procedure and enabling knowledge of the DAD method is introduced. The application case of DAD method in the ultra-precision flycutting machine tool for KDP crystal machining is described to show the procedure detailedly. In this case, the KDP workpiece surface has the requirements in four different spatial frequency bands, and the emphasis for this study is put on the middle-frequency band with the PSD specifications. The results of the application case basically show the feasibility of the proposed DAD method. The DAD method of ultra-precision machine tool can effectively minimize the technical risk and improve the machining reliability of the designed machine tool. This paper will play an important role in the design and manufacture of new ultra-precision machine tool.
文摘The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the transfer matrix method for multibody systems.In particular,the large-span scale flow field mesh model was created;and the variation in linear and angular stiffness of journal and thrust bearings with respect to film thickness was investigated by adopting the dynamic mesh technique.The dynamic model was proven to be valid by comparing the dynamic characteristics of the machine tool obtained by numerical simulation with the experimental results.In addition,the power spectrum density estimation method was adopted to simulate the statistical ambient vibration excitation by processing the ambient vibration signal measured over a long period of time.Applying it to the dynamic model,the dynamic response of the tool tip under ambient vibration was investigated.The results elucidated that the tool tip response was significantly affected by ambient vibration,and the isolation foundation had a good effect on vibration isolation.
文摘In order to minimize vibration and improve rotary precision of spindle, we apply active vibration control technique to ultra-precision turning machine based on the analysis of vibration characteristic of aerostatic bearing spindle. Using aerostatic bearing itself as actuator, the vibration of spindle is controlled by adjusting admission pressure respectively and by changing pressure distribution in the bearing. The experiments and simulations prove that this method can minimize the vibration of spindle effectively.
基金This project is supported by Foundation of Xiamen Univer sity of China for Scholars Return from Abroad (No.08003).
文摘A new idea for designing wheel patterns is presented so as to solve theproblems about machining accuracy of workpiece and wear of honing wheel in ultra-precision planehoning. The influence factors on motion principle and pattern structures are analyzed andoptimization machining parameters are obtained. By calculating effective cutting length on thesurface of workpiece cut by wheel's abrasive and the orbit of one point on the surface of workpiececontacting with wheel, the wear coefficient of different kinds of wheels and accuracy coefficient ofworkpiece machined by corresponding wheels are obtained. Furthermore, the simulation results showthat the optimal pattern structure of wheel turns out to have lower wheel wear and higher machiningaccuracy.
基金supported by the NSF under grant No. CMMI-1844821。
文摘In this paper, the modified slip/fracture activation model has been used in order to understand the mechanism of ductile-brittle transition on the R-plane of sapphire during ultra-precision machining by reflecting direction of resultant force. Anisotropic characteristics of crack morphology and ductility of machining depending on cutting direction were explained in detail with modified fracture cleavage and plastic deformation parameters. Through the analysis, it was concluded that crack morphologies were mainly determined by the interaction of multiple fracture systems activated while, critical depth of cut was determined by the dominant plastic deformation parameter. In addition to this, by using proportionality relationship between magnitude of resultant force and depth of cut in the ductile region, an empirical model for critical depth of cut was developed.
基金the Research Committee of The Hong Kong Polytechnic University and the Innovation Technology Commission of The Hong Kong SAR Government for their financial support of the Hong Kong Partner State Key Laboratory of Ultra-Precision Machining Technology
文摘There have been various theoretical attempts by researchers worldwide to link up different scales of plasticity studies from the nano-, micro- and macro-scale of observation, based on molecular dynamics, crystal plasticity and continuum mechanics. Very few attempts, however, have been reported in ultra-precision machining studies. A mesoplasticity approach advocated by Lee and Yang is adopted by the authors and is successfully applied to studies of the micro-cutting mechanisms in ultra-precision machining. Traditionally, the shear angle in metal cutting, as well as the cutting force variation, can only be determined from cutting tests. In the pioneering work of the authors, the use of mesoplasticity theory enables prediction of the fluctuation of the shear angle and micro-cutting force, shear band formation, chip morphology in diamond turning and size effect in nano-indentation. These findings are verified by experiments. The mesoplasticity formulation opens up a new direction of studies to enable how the plastic behaviour of materials and their constitutive representations in deformation processing, such as machining can be predicted, assessed and deduced from the basic properties of the materials measurable at the microscale.
文摘During ultra-precision machining, machining accuracy is determined by many factors and interaction of these factors. Error sources are systematically analyzed for ultra-precision machine tools, and the influencing degree of each factor is presented to provide orientation for error reduction and error compensation.
文摘Digital manufacturing technology can be used in optical field to solve many problems caused by traditional machining. According to the characters of digital manufacturing and the practical applications of ultra-precision machining,the process of digital ultra-precision machining and its technical contents were presented in this paper. In the conclusions,it was stated that the digitalization of ultra-precision machining will be an economical and efficient way for the production of new sorts of optical workpieces.
基金supported by the National Natural Science Foundation of China under Grant No.61434006
文摘This paper presents a terahertz(THz)band-pass filter using ultra-precision machining technology based on Chebyshev filter prototype.This iris inductive window coupled waveguide filter was designed by using 8 resonant cavities with a center frequency of 345 GHz and a 7% bandwidth.The final design fulfills the desired specifications and presents the minimum insertion loss of 1.55 d B and the return loss of less than 15 d B at 345 GHz.The stop-band rejection is50 d B off the center frequency about 30 GHz,which means it has a good performance of high stop-band suppression.Compared with the recent development of THz filters,this filter possesses the characteristic of simple structure and is easy to machining.
文摘Free abrasive particle machining in simple machine such as: honing, polishing can get higher surface finish mirror, but surface error, and working procedure is hard to control. Therefore, the vertical disposed ultra-precision plane honing method by ultra-particle diamond honing wheel is put forward to. The results of experiments indicate: plane-honing wheel has higher machining accuracy and machining efficiency. But at the same time the structure parameters of honing wheel effects on machining accuracy. By analyzing the relation of honing wheel structure parameters and workpiece machining accuracy, the relation of honing wheel and wear coefficient, then this paper gets honing wheel structure parameters in the condition of best accuracy coefficient and wear coefficient, and resolve the problem of choosing honing wheel structure parameters in ultra-precision plane honing at last. This paper analyses the relation of honing wheel structure parameters and workpiece machining accuracy coefficient and wear coefficient, by building relative movement math model of honing wheel and workpiece in plane honing. Through theory calculating, the result indicate: about honing machine tools for large volume manufacture, honing wheel wear is main effect factor, so honing wheel should adopt obverse triangle radial structure. About honing machining for high accuracy and low-batch quantities, machining accuracy coefficient is main factors; so honing wheel should adopt reverse triangle radial structure. Neglected the manufacturing factors of honing wheel, then we can design honing wheel with high power curve structure to meet the need of machining accuracy coefficient and honing wheel wear coefficient in higher accuracy honing.
基金supports of the Funds for the National Natural Science Foundation of China [grant numbers 51575386,51275344]
文摘With the increasing market demand for optical complex surface parts,the application of multi-axis ultraprecision single-point diamond turning is increasing.A tool path generation method is very important to decrease manufacturing time,enhance surface quality,and reduce cost.Compared with the tool path generation of the traditional multi-axis milling,that of the ultra-precision single-point diamond turning requires higher calculation accuracy and efficiency.This paper reviews the tool path generation of ultra-precision diamond turning,considering several key issues:cutter location(CL)points calculation,the topological form of tool path,interpolation mode,and G code optimization.
基金supported by the National Key Research and Development Project of China(Grant No.2020YFB1710400)the National Natural Science Foundation of China(Grant No.52005205)the National Science Fund for Distinguished Young Scholars(Grant No.52225506)。
文摘The surface finish quality is critical to the service performance of a machined part,and single-point diamond ultra-precision machining can achieve excellent surface quality for many engineering materials.This study studied the problem of predicting the surface roughness for titanium alloy workpieces in ultra-precision machining.Process data and surface roughness measurement results were obtained during end-face machining experiments.A deep learning neural network model was built based on the ResNet-50 architecture to predict surface roughness.We propose increasing prediction accuracy by using the energy ratio difference(ERD)as a stability feature that can be extracted using fast iterative variational mode decomposition(FI-VMD).The roughness value obtained with an analytic model was also used as an input feature of the prediction model.The prediction accuracy of the proposed approach was depicted to be improved by 8.7%with the two newly introduced roughness predictors.The influence of the tool parameters on the prediction accuracy was investigated,and the proposed hybrid-driven model exhibited higher robustness to errors of the tool parameters than the analytic roughness model.
基金the financial support provided by the National Key Research and Development Program(Grant No.2018YFA0702900)the National Natural Science Foundation of China(Grant No.51975096).
文摘The tool state exerts a strong influence on surface quality and profile accuracy during precision/ultraprecision machining.However,current on-machine measurement methods cannot precisely obtain the tool nose radius and wear.This study therefore investigated the onmachine measurement of tool nose radius on the order of hundreds of microns and wear on the order of a few microns to tens of microns during precision/ultra-precision machining using the edge reversal method.To provide the necessary replication,pure aluminum and pure copper soft metal substrates were evaluated,with pure copper exhibiting superior performance.The feasibility of the measurement method was then demonstrated by evaluating the replication accuracy using a 3D surface topography instrument;the measurement error was only 0.1%.The wear of the cutting tool was measured using the proposed method to obtain the maximum values for tool arc wear,flank wear,and wear depth of 3.4 lm,73.5 lm and 3.7 lm,respectively.
基金Acknowledgements The authors would like to acknowledge the financial support from the National Natural Science of China (General Program) (Grant No. 51575083), the Major Research plan of the National Natural Science Foundation of China (Grant No. 91323302), the Science Fund for Creative Research Groups (Grant No. 51621064), and the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 51505063).
文摘Hard and brittle materials, such as silicon, SiC, and optical glasses, are widely used in aerospace, military, integrated circuit, and other fields because of their excellent physical and chemical properties. However, these materials display poor machinability because of their hard and brittle properties. Damages such as surface micro-crack and subsurface damage often occur during machining of hard and brittle materials. Ultra-precision machining is widely used in processing hard and brittle materials to obtain nanoscale machining quality. However, the theoretical mechanism underlying this method remains unclear. This paper provides a review of present research on the molecular dynamics simulation of ultra-precision machining of hard and brittle materials. The future trends in this field are also discussed.
基金supported by National Natural Science Foundation of China(No.51875579)the Fundamental Research Fund for the Central Universities,China(No.19CX02023A)+2 种基金the Major Research Project of Shandong Province,China(No.2019GGX104068)the Science and Technology Support Plan for Youth Innovation of Universities in Shandong Province,China(No.2019KJB016)Source Innovation Project of Qingdao West Coast New Area,China(No.2020-82)。
文摘The nickel-based superalloy Inconel 718 is treated with Coupled Ultrasonic and Electric Pulse Treatment(CUEPT),and the surface grain is refined from the average size of 9550.0 nm to287.9,216.3,150.5,126.3,25.8 nm by different effective treatment currents,respectively.The ultraprecision turning experiments are carried out on the processed workpiece after CUEPT.The experimental results show that the average cutting force increases with the decrease of surface grain size.Moreover,a mathematical model that can describe the relationship between grain size and cutting force is established,and the calculated results match the experimental results well.The calculated results also indicate that the variation of cutting force caused by the same variation of grain size decreases as the degree of grain refinement increases.Finally,the influence mechanism of grain refinement on cutting force is analyzed.The improvement of stability of grain boundaries and the increase of number of grain boundaries cause the increase of cutting force after grain refinement.
基金the UK’s Engineering and Physical Sciences Research Council(EPSRC)funding of Future Metrology Hub(Ref.:EP/P006930/1)the UK’s Science and Technology Facilities Council(STFC)Innovation Partnership Scheme(IPS)project under Grant Agreement No.ST/V001280/1the European Union’s Horizon 2020research and innovation programme under Grant Agreement No.767589。
文摘Freeform optics has become the most prominent element of the optics industry. Advanced freeform optical designs supplementary to ultra-precision manufacturing and metrology techniques have upgraded the lifestyle, thinking, and observing power of existing humans.Imaginations related to space explorations, portability, accessibility have also witnessed sensible in today’s time with freeform optics. Present-day design methods and fabrications techniques applicable in the development of freeform optics and the market requirements are focussed and explained with the help of traditional and non-traditional optical applications. Over the years,significant research is performed in the emerging field of freeform optics, but no standards are established yet in terms of tolerances and definitions. We critically review the optical design methods for freeform optics considering the image forming and non-image forming applications. Numerous subtractive manufacturing technologies including figure correction methods and metrology have been developed to fabricate extreme modern freeform optics to satisfy the demands of various applications such as space, astronomy, earth science, defence,biomedical, material processing, surveillance, and many more. We described a variety of advanced technologies in manufacturing and metrology for novel freeform optics. Next, we also covered the manufacturing-oriented design scheme for advanced optics. We conclude this review with an outlook on the future of freeform optics design, manufacturing and metrology.
文摘Active vibration control is widely used in both defence and civil industries and therefore, its principle and design are discussed, and acceleration, velocity and displacement of the mass are used as the input variables for the controller. In practice, the time delay of mechanical system should be taken into consideration. An experiment has been successfully made with a HCM-I ultra-precision turning machine. Experimental results indicate that active vibration control can effectively isolate the vibration from the base, and the vibration transmissibility from base to the machine is distinct descend.
基金the support of the Deutsche Forschungsgemeinschaft(DFG)in the framework of Research Training Group“Tip-and laser-based 3D-nanofabrication in extended macroscopic working areas”(GRK 2182)at the Technische Universitat Ilmenau,Germany。
文摘The majority of nanopositioning and nanomeasuring machines(NPMMs)are based on three independent linear movements in a Cartesian coordinate system.This in combination with the specific nature of sensors and tools limits the addressable part geometries.An enhancement of an NPMM is introduced by the implementation of rotational movements while keeping the precision in the nanometer range.For this purpose,a parameter-based dynamic evaluation system with quantifiable technological parameters has been set up and employed to identify and assess general solution concepts and adequate substructures.Evaluations taken show high potential for three linear movements of the object in combination with two angular movements of the tool.The influence of the additional rotation systems on the existing structure of NPMMs has been investigated further on.Test series on the repeatability of an NPMM enhanced by a chosen combination of a rotary stage and a goniometer setup are realized.As a result of these test series,the necessity of in situ position determination of the tool became very clear.The tool position is measured in situ in relation to a hemispherical reference mirror by three Fabry-Perot interferometers.FEA optimization has been used to enhance the overall system structure with regard to reproducibility and long-term stability.Results have been experimentally investigated by use of a retroreflector as a tool and the various laser interferometers of the NPMM.The knowledge gained has been formed into general rules for the verification and optimization of design solutions for multiaxial nanopositioning machines.
基金supported by the National Natural Science Foundation of China(Grant Nos.50875242,50905163)Key Project of Natural Science Foundation of Zhejiang Province(Grant Nos.Z107517,Y1090836)
文摘Aiming at the problem of difficult contact finishing for mini structural surface in course of mould manufacturing,a new no-tool precision machining method based on soft abrasive flow machining (SAFM) was proposed. It allocated restrained component near surface machined,constituted restrained abrasive flow passage,and made the surface become a segment of passage wall. It could control turbulence abrasive flow in restrained passage,realize micro cutting for passage wall,and utilize the irregular motion of abrasive flow to eliminate the mono-directional marks on machined surfaces,and the precision could reach the specular level. A two-phase dynamic model of abrasive flow oriented to SAFM combined with discrete phase model (DPM) was established,the law of two-phase flow motion and the related physical parameters was obtained by corresponding numerical simulation method,and the mechanism of precision machining in SAFM was discussed. Simulation results show that the abrasive flow machining process mainly appears as translation of ablating location with the influence by granular pressure,and as the variation of machining efficiency with the influence by near-wall particle velocity. Thus via control of the inlet velocity and its corresponding machining time,it is supposed to work out the machining process according to the machining requirements by using the Preston equation to seek the relationship among velocity,pressure and material removing rate. By tracking near-wall particles,it can be confirmed that the movement of near-wall abrasive particles is similar to stream-wise vortices. The cutting traces on workpiece surfaces assume disorderly arrangement,so the feasibility of the SAFM method can be reaffirmed.
基金supported by the National Natural Science Foundation of China (Nos.51171098,and 51222102)the Research Grants Council of Hong Kong (No.Poly U511211)+2 种基金the Innovation Program of Shanghai Municipal Education Commission (No.12ZZ090)the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learningthe "085 Project" in Shanghai University
文摘Cutting behavior exerts a considerable influence on the fabrication of bulk metallic glass(BMG) components. In this study,the influences of machining parameters(i.e.,depth of cutting,feed rate,and spindle rate) on the turned surface of a Zr-based BMG after observing the 3D morphologies of this surface were characterized.The results showed that the influence of the spindle rate on the surface morphologies is more substantial as compared to the depth of cutting and the feed rate. Nanoscratch tests were conducted to further characterize the separation mechanism of the chips,which revealed that the chips are torn off the surface of a BMG because of inhomogeneous localized maximum shear stress.