The vibration disturbance from an external environment affects the machining accuracy of ultra-precision machining equipment.Most active vibration-isolation systems(AVIS)have been developed based on static loads.When ...The vibration disturbance from an external environment affects the machining accuracy of ultra-precision machining equipment.Most active vibration-isolation systems(AVIS)have been developed based on static loads.When a vibration-isolation load changes dynamically during ultra-precision turning lathe machining,the system parameters change,and the efficiency of the active vibration-isolation system based on the traditional control strategy deteriorates.To solve this problem,this paper proposes a vibration-isolation control strategy based on a genetic algorithm-back propagation neural network-PID control(GA-BP-PID),which can automatically adjust the control parameters according to the machining conditions.Vibration-isolation simulations and experiments based on passive vibration isolation,a PID algorithm,and the GA-BP-PID algorithm under dynamic load machining conditions were conducted.The experimental results demonstrated that the active vibration-isolation control strategy designed in this study could effectively attenuate vibration disturbances in the external environment under dynamic load conditions.This design is reasonable and feasible.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
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
The effects of the nonuniform cutting force and elastic recovery of processed materials in ultra-precision machining are too complex to be treated using traditional cutting theories,and it is necessary to take account...The effects of the nonuniform cutting force and elastic recovery of processed materials in ultra-precision machining are too complex to be treated using traditional cutting theories,and it is necessary to take account of factors such as size effects,the undeformed cutting thickness,the tool blunt radius,and the tool rake angle.Therefore,this paper proposes a new theoretical calculation model for accurately predicting the cutting force in ultra-precision machining,taking account of such factors.The model is first used to analyze the material deformation of the workpiece and the cutting force distribution along the cutting edge of a diamond tool.The size of the strain zone in different cutting deformation zones is then determined by using the distribution of strain work per unit volume and considering the characteristics of the stress distribution in these different deformation zones.Finally,the cutting force during ultra-precision machining is predicted precisely by calculating the material strain energy in different zones.A finite element analysis and experimental data on ultra-precision cutting of copper and aluminum are used to verify the predictions of the theoretical model.The results show that the error in the cutting force between the calculation results and predictions of the model is less than 14%.The effects of the rake face stress distribution of the diamond tool,the close contact zone,and material elastic recovery can be fully taken into account by the theoretical model.Thus,the proposed theoretical calculation method can effectively predict the cutting force in ultra-precision machining.展开更多
The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cu...The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cutting parameters were conducted. Cutting temperature was measured by FLIR A315 infrared thermal imager. Tool wear was measured by scanning electron microscope(SEM). The numerical model of heat flux considering tool wear generated in cutting zone was established. Then two-step finite element method(FEM) simulations matching the experimental conditions were carried out to simulate the thermal deformation. In addition, the tests of deformation of tool system were performed to verify previous simulation results. And then the influence of cutting parameters on thermal deformation was investigated. The results show that the temperature and thermal deformation from simulations agree well with the results from experiments in the same conditions. The maximum thermal deformation of tool reaches to 7 μm. The average flank wear width and cutting speed are the dominant factors affecting thermal deformation, and the effective way to decrease the thermal deformation of tool is to control the tool wear and the cutting speed.展开更多
The BLU (back light unit) is the core component of the LCD for notebook, mobile-phone, navigation, as well as large sized TV, PID (public information display), etc. In order to enhance optical efficiency of LCD, optic...The BLU (back light unit) is the core component of the LCD for notebook, mobile-phone, navigation, as well as large sized TV, PID (public information display), etc. In order to enhance optical efficiency of LCD, optical films with the uniform prism patterns have been used for BLU by stacking two films up orthogonally. In this case, light interference-phenomenon occurred such as Morie, wet-out, u-turning, etc. It caused several problems such as low brightness, spots and stripes in LCD. Recently, the high-luminance micro complex prism patterns are actively studied to avoid the light interference-phenomenon and enhance the optical efficiency. In this study, the roll master to manufacture complex micro prism pattern film was machined by using the high precision lathe. The machined patterns on the roll master were 50, 45, 40, 35, 30, 25, 20, 15, 10 and 5 μm in the pitch with 25.0, 22.5, 20.0, 17.5, 15.0, 12.5, 10.0, 7.5, 5.0 and 2.5 μm in the peak height, respectively. The roll was 2 000 mm in length and 320 mm in diameter. The electroplated roll by copper and the natural single crystal diamond tool was used for machining the patterns. The cutting force was measured and analyzed for each cutting condition by using the dynamometer. The chips and the surfaces after being machined were analyzed by SEM and microscope.展开更多
Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has...Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has been presented to produce a micro-step pillar array as an embossing mold for semiconductor application.Theoretical analysis on machining mechanics indicates that work material property,machining strategy,and cutting tool geometry largely afFect machining distortion on the machined microstructure.Experimental investigation has been conducted on micromachining of the micro-step pillar array using different types of cutting tools and work materials.Experimental results demonstrate that the material property,cutting tool edge radius,and cutting force play a significant role in the machined micro-structure accuracy and surface finish,while grain boundary of brass has no significant effect on the micro-milling performance.The best outcome among the tests done is achieved when using brass as work material and cutting with a straight-edge single crystalline diamond tool.The main reasons to achieve this outcome are based on:the brass material having a higher elastic modulus and the diamond tool having a smaller cutting edge radius,which contributes to better machinability of brass.One micro-step pillar array has been successfully obtained with very precise feature and dimensional accuracy using brass work material and single-crystal diamond tool.It is believed that the outcomes of this study would largely benefit the research community and end-users.展开更多
This paper describes a completely new dressing technique, the soft-elastic dressing method, which can effectively dress fine grain diamond wheels. A rotating and vibrating abrasive belt is used in the soft-elastic dre...This paper describes a completely new dressing technique, the soft-elastic dressing method, which can effectively dress fine grain diamond wheels. A rotating and vibrating abrasive belt is used in the soft-elastic dressing method. The principle of the new dressing technique and the soft-elastic dressing equipment are presented. Factors that influence the truing efficiency, truing precision and sharpening quality are carefully investigated. The grinding surface roughness after soft-elastic dressing is performed is investigated experimentally. The dressing and grinding experiments both prove that the soft-elastic dressing method has high truing efficiency, high truing precision and good sharpening quality.[展开更多
ALTHOUGH a lot of research work on diamond mineralogy has already been done,the formationand development of diamond leave much to be explored.We have done some researches onthe diamond samples with obvious crystal-gro...ALTHOUGH a lot of research work on diamond mineralogy has already been done,the formationand development of diamond leave much to be explored.We have done some researches onthe diamond samples with obvious crystal-growing characteristics in the last few years.Hereare reported some of our discoveries and viewpoints.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62073184,52105490).
文摘The vibration disturbance from an external environment affects the machining accuracy of ultra-precision machining equipment.Most active vibration-isolation systems(AVIS)have been developed based on static loads.When a vibration-isolation load changes dynamically during ultra-precision turning lathe machining,the system parameters change,and the efficiency of the active vibration-isolation system based on the traditional control strategy deteriorates.To solve this problem,this paper proposes a vibration-isolation control strategy based on a genetic algorithm-back propagation neural network-PID control(GA-BP-PID),which can automatically adjust the control parameters according to the machining conditions.Vibration-isolation simulations and experiments based on passive vibration isolation,a PID algorithm,and the GA-BP-PID algorithm under dynamic load machining conditions were conducted.The experimental results demonstrated that the active vibration-isolation control strategy designed in this study could effectively attenuate vibration disturbances in the external environment under dynamic load conditions.This design is reasonable and feasible.
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This work was supported by the National Natural Science Foundation of China(Grant No.51305278)the Liaoning Revitalization Talents Program,China(GrantNo.XLYC2007133)the Natural Science Foundation of Liaoning Province,China(GrantNo.2020-MS-213).
文摘The effects of the nonuniform cutting force and elastic recovery of processed materials in ultra-precision machining are too complex to be treated using traditional cutting theories,and it is necessary to take account of factors such as size effects,the undeformed cutting thickness,the tool blunt radius,and the tool rake angle.Therefore,this paper proposes a new theoretical calculation model for accurately predicting the cutting force in ultra-precision machining,taking account of such factors.The model is first used to analyze the material deformation of the workpiece and the cutting force distribution along the cutting edge of a diamond tool.The size of the strain zone in different cutting deformation zones is then determined by using the distribution of strain work per unit volume and considering the characteristics of the stress distribution in these different deformation zones.Finally,the cutting force during ultra-precision machining is predicted precisely by calculating the material strain energy in different zones.A finite element analysis and experimental data on ultra-precision cutting of copper and aluminum are used to verify the predictions of the theoretical model.The results show that the error in the cutting force between the calculation results and predictions of the model is less than 14%.The effects of the rake face stress distribution of the diamond tool,the close contact zone,and material elastic recovery can be fully taken into account by the theoretical model.Thus,the proposed theoretical calculation method can effectively predict the cutting force in ultra-precision machining.
基金Project(51175122)supported by the National Natural Science Foundation of China
文摘The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cutting parameters were conducted. Cutting temperature was measured by FLIR A315 infrared thermal imager. Tool wear was measured by scanning electron microscope(SEM). The numerical model of heat flux considering tool wear generated in cutting zone was established. Then two-step finite element method(FEM) simulations matching the experimental conditions were carried out to simulate the thermal deformation. In addition, the tests of deformation of tool system were performed to verify previous simulation results. And then the influence of cutting parameters on thermal deformation was investigated. The results show that the temperature and thermal deformation from simulations agree well with the results from experiments in the same conditions. The maximum thermal deformation of tool reaches to 7 μm. The average flank wear width and cutting speed are the dominant factors affecting thermal deformation, and the effective way to decrease the thermal deformation of tool is to control the tool wear and the cutting speed.
基金Project(R15-2006-022-01001-0) supported by the National Core Research Center Program from MOST and KOSEF
文摘The BLU (back light unit) is the core component of the LCD for notebook, mobile-phone, navigation, as well as large sized TV, PID (public information display), etc. In order to enhance optical efficiency of LCD, optical films with the uniform prism patterns have been used for BLU by stacking two films up orthogonally. In this case, light interference-phenomenon occurred such as Morie, wet-out, u-turning, etc. It caused several problems such as low brightness, spots and stripes in LCD. Recently, the high-luminance micro complex prism patterns are actively studied to avoid the light interference-phenomenon and enhance the optical efficiency. In this study, the roll master to manufacture complex micro prism pattern film was machined by using the high precision lathe. The machined patterns on the roll master were 50, 45, 40, 35, 30, 25, 20, 15, 10 and 5 μm in the pitch with 25.0, 22.5, 20.0, 17.5, 15.0, 12.5, 10.0, 7.5, 5.0 and 2.5 μm in the peak height, respectively. The roll was 2 000 mm in length and 320 mm in diameter. The electroplated roll by copper and the natural single crystal diamond tool was used for machining the patterns. The cutting force was measured and analyzed for each cutting condition by using the dynamometer. The chips and the surfaces after being machined were analyzed by SEM and microscope.
文摘Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has been presented to produce a micro-step pillar array as an embossing mold for semiconductor application.Theoretical analysis on machining mechanics indicates that work material property,machining strategy,and cutting tool geometry largely afFect machining distortion on the machined microstructure.Experimental investigation has been conducted on micromachining of the micro-step pillar array using different types of cutting tools and work materials.Experimental results demonstrate that the material property,cutting tool edge radius,and cutting force play a significant role in the machined micro-structure accuracy and surface finish,while grain boundary of brass has no significant effect on the micro-milling performance.The best outcome among the tests done is achieved when using brass as work material and cutting with a straight-edge single crystalline diamond tool.The main reasons to achieve this outcome are based on:the brass material having a higher elastic modulus and the diamond tool having a smaller cutting edge radius,which contributes to better machinability of brass.One micro-step pillar array has been successfully obtained with very precise feature and dimensional accuracy using brass work material and single-crystal diamond tool.It is believed that the outcomes of this study would largely benefit the research community and end-users.
文摘This paper describes a completely new dressing technique, the soft-elastic dressing method, which can effectively dress fine grain diamond wheels. A rotating and vibrating abrasive belt is used in the soft-elastic dressing method. The principle of the new dressing technique and the soft-elastic dressing equipment are presented. Factors that influence the truing efficiency, truing precision and sharpening quality are carefully investigated. The grinding surface roughness after soft-elastic dressing is performed is investigated experimentally. The dressing and grinding experiments both prove that the soft-elastic dressing method has high truing efficiency, high truing precision and good sharpening quality.[
文摘ALTHOUGH a lot of research work on diamond mineralogy has already been done,the formationand development of diamond leave much to be explored.We have done some researches onthe diamond samples with obvious crystal-growing characteristics in the last few years.Hereare reported some of our discoveries and viewpoints.
